WO2018122974A1

WO2018122974A1 - Wireless communication system and method of controlling wireless communication system

Info

Publication number: WO2018122974A1
Application number: PCT/JP2016/088938
Authority: WO
Inventors: 小林　正典
Original assignee: 三菱電機株式会社
Priority date: 2016-12-27
Filing date: 2016-12-27
Publication date: 2018-07-05

Abstract

The purpose of the present invention is to provide a wireless communication system and a method of controlling the wireless communication system for recovering a wireless link early when disruption or quality degradation of wireless communication between a base station and a wireless communication terminal occurs. In a wireless communication system according to the present invention, a base station having detected disruption or quality degradation of wireless communication transmits a wireless link recovery request to each of base stations written in an antenna setting order list, with antenna setting information for recovery of the same wireless link included in each of the transmitted wireless link recovery requests, and a transmitting/receiving unit 10 of the base station having transmitted the wireless link recovery request and each of the base stations having received the wireless link recovery request transmits a training signal for wireless link recovery on the basis of the antenna setting order list and time-of-day information at a time when the training signal for wireless link recovery is not transmitted at the same frequency simultaneously from a plurality of base stations.

Description

Radio communication system and radio communication system control method

The present invention relates to a radio communication system and a control method for the radio communication system, and more particularly to a radio communication system that performs interconnection by controlling the direction of a transmit / receive beam of an antenna by changing antenna settings.

In advanced mobile communications, a fifth-generation (hereinafter sometimes referred to as “5G”) wireless access system targeted to start a service after 2020 is being studied.

In the 5G wireless access system, the system capacity is 1000 times that of the LTE system, the data transmission speed is 100 times, the data processing delay is 1/10 (1/10), and the wireless terminal device is simultaneously connected to one base station. The number is set to 100 times, and further reduction of power consumption and cost reduction of the apparatus are listed as requirements.

In order to satisfy the above requirements, use of antenna beam forming technology to increase the data transmission capacity by using the frequency in a wide band and increase the data transmission capacity by increasing the frequency efficiency to enable spatial multiplexing Is being considered. In order to secure a wideband frequency, it has been studied to use a high frequency such as a 3-30 GHz microwave (Super High Frequency: SHF) band as a frequency used for wireless access.

Antenna beam forming has a feature that multipath is difficult to occur because the antenna beam width becomes narrow. Furthermore, microwaves are characterized by high straightness. Therefore, in the 5G wireless access system, a radio link failure due to a shield is likely to occur, and when a radio link failure occurs, it is a problem to recover the radio link at an early stage.

In response to the above problem, Patent Document 1 discloses a method of quickly recovering from a radio link failure by using a reflected wave. In general, a long time is allowed when establishing a wireless link in the initial stage. Therefore, in the training for initial wireless link establishment, antenna setting pairs corresponding to propagation paths that can be used for multiple communications are acquired and stored in advance, and communication interruptions and communication quality degradation occur due to shielding objects etc. In this case, a new antenna setting pair is selected from the reserved antenna setting pairs stored.

Also, in 5G, a method of improving coverage and throughput by coordinating transmission / reception between adjacent base stations (Coordinated Multi-Point: CoMP) is being studied. The method for recovering from the radio link failure described above can be applied to CoMP as well.

For example, assume a case where a wireless terminal device has a total of eight antenna setting pairs x1 to x8 with three base stations. Currently, the wireless terminal device is in a state of establishing a wireless link using the antenna setting pair x1. Here, when the wireless link of the antenna setting pair x1 is interrupted due to the appearance of a shield or the like, the wireless communication is quickly performed by selecting a new antenna setting from the reserved antenna setting pairs x2, x3. Try to recover the link. In Non-Patent Document 1, it is proposed that a base station that has detected that a radio link has been disconnected notifies an adjacent base station to realize early radio link recovery.

International Publication No. 2011/055536

The 5G wireless access system that employs antenna beam forming technology and microwaves has a problem that a radio link failure due to a shield is likely to occur. In Patent Document 1, in training when establishing a radio link, antenna setting pairs corresponding to propagation paths that can be used for a plurality of communications are acquired and stored in advance, and communication is interrupted or communication quality is deteriorated due to a shielding object or the like. When this occurs, a method has been proposed in which a radio link is recovered quickly by switching from a stored pair of spare antenna settings to a new antenna setting pair.

Also, in the 5G wireless access system, a method in which a plurality of base stations operate in a coordinated manner has been studied, and the antenna setting pair in the above proposal extends over a plurality of base stations.

In order to recover the radio link, it is necessary to resynchronize between the base station and the radio terminal device by transmitting and receiving a training signal. Therefore, in order to recover the radio link at an early stage, it is desirable that the base station that has detected the radio link failure and the radio terminal apparatus immediately start transmission / reception of training signals. Further, as proposed in Non-Patent Document 1, a base station that detects a radio link failure notifies an adjacent base station, and the adjacent base station cooperates to recover the radio link for further improvement. Can be expected.

Here, an emphasis operation is required for a plurality of base stations to transmit training signals. For example, when training signals of the same frequency are transmitted from a plurality of base stations at the same time, if the receiving antenna setting on the wireless terminal device side is pseudo omni (that is, omnidirectional), a plurality of training signals Cannot be recognized separately. When attempting to restore the radio link at an early stage, it is desirable that training signals from all directions can be received at all times, and the receiver side of the training signals is generally set to be a pseudo omni.

As described above, the method of transmitting training signals with emphasis at multiple base stations is necessary for the early recovery of the radio link, but the method of operating in a coordinated manner between the base stations is specifically shown in the prior art. Not.

The present invention has been made to solve the above-described problems. When wireless communication is interrupted or quality degradation occurs between a base station and a wireless communication terminal, the wireless communication terminal is connected to a plurality of base stations. It is an object of the present invention to provide a radio communication system and a control method for the radio communication system that can quickly restore a radio link by transmitting a training signal at an appropriate frequency and an appropriate timing.

A wireless communication system according to the present invention includes a plurality of base stations that can communicate with each other, and each of the plurality of base stations can wirelessly communicate with at least one wireless terminal device, and at least one wireless terminal device includes: The directivity of the transmission beam and the reception beam can be changed by changing the antenna setting, and each of the plurality of base stations has a transmission / reception unit capable of changing the directivity of the transmission beam and the reception beam, and a wireless terminal device. Stores a degradation detection unit that detects communication interruption or degradation of communication quality in radio communication, a radio link recovery antenna setting information generation unit that generates radio link recovery antenna setting information, and radio link recovery antenna setting information. A storage unit, and a control unit that controls the directivity of the transmission beam and the reception beam by changing antenna settings of the transmission / reception unit; And when the deterioration detection unit of the base station that is performing wireless communication with at least one wireless terminal device among the plurality of base stations detects wireless communication interruption or communication quality deterioration, the wireless communication interruption or deterioration is detected. The detected radio link recovery antenna setting information generation unit of the detected base station generates radio link recovery antenna setting information based on the antenna setting pair candidate list, and the antenna setting pair candidate list includes at least one wireless terminal device and a plurality of antenna setting pair candidate lists. The antenna setting pair candidate list is generated in the initial training for starting wireless communication with any one of the base stations, and the antenna setting pair candidate list identifies the antenna setting of the at least one wireless terminal device and the base station Is a list of combinations of information and base station antenna settings identified by the identification information, and radio link recovery antenna settings The information includes an antenna setting order list and time information serving as a reference for the time at which the transmission of the radio link recovery training signal is started. The antenna setting order list includes identification information for identifying a base station and identification information. This is a list that defines the order of combinations with the antenna settings of the identified base stations, and the base station that detects the disruption or degradation of the radio communication receives the radio link recovery for each of the base stations described in the antenna setting order list. Each of the transmitted radio link recovery requests includes the same radio link recovery antenna setting information, and the base station that transmitted the radio link recovery request and the radio link recovery request are received. Each transmitting / receiving unit of the base station has the same radio link recovery training signal based on the antenna setting order list and time information. The radio link recovery training signal is transmitted at a timing that is not simultaneously transmitted from a plurality of base stations at a frequency, and the radio link recovery training signal is a training signal transmitted with the antenna setting described in the antenna setting order list.

In the control method of the wireless communication system according to the present invention, the wireless communication system includes a plurality of base stations that can communicate with each other, and each of the plurality of base stations can wirelessly communicate with at least one wireless terminal device, One wireless terminal device can change the directivity of the transmission beam and the reception beam by changing the antenna setting, and each of the plurality of base stations can change the direction of the transmission beam and the reception beam by changing the antenna setting. The directivity can be changed, and the control method of the wireless communication system is as follows: (a) Among a plurality of base stations, a base station that is performing wireless communication with at least one wireless terminal device (B) After step (a), the base station that detected the disruption or degradation of wireless communication is added to the antenna setting pair candidate list. And generating the radio link recovery antenna setting information, and the antenna setting pair candidate list is for starting radio communication between at least one radio terminal device and any of a plurality of base stations. The antenna setting pair candidate list generated in the initial training includes an antenna setting of at least one wireless terminal device, identification information for identifying a base station, and antenna setting for the base station identified by the identification information. The radio link recovery antenna setting information includes an antenna setting order list and time information serving as a reference for the time to start the radio link recovery process. The antenna setting order list indicates the base station A list that specifies the order of combinations of identification information to be identified and base station antenna settings identified by the identification information. Thus, in the control method of the radio communication system, (c) after step (b), the base station that detects the disruption or deterioration of radio communication receives radio link recovery from each of the base stations described in the antenna setting order list. The wireless link recovery request to be transmitted includes the same wireless link recovery antenna setting information, and the control method of the wireless communication system includes the step (d) ( After c), the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request have the radio link recovery training signal at the same frequency based on the antenna setting order list and the time information. The wireless link recovery tray further comprises a step of transmitting a radio link recovery training signal at a timing not simultaneously transmitted from a plurality of base stations. The training signal is a training signal transmitted with the antenna setting described in the antenna setting order list.

According to the radio communication system and the radio communication system control method according to the present invention, a plurality of base stations share the same antenna setting order list and the same time information in the radio link recovery process. As a result, each of the plurality of base stations transmits the radio link at a timing at which the antenna setting training signal (that is, the radio link recovery training signal) described in the antenna setting order list is not simultaneously transmitted from the plurality of base stations at the same frequency. A recovery training signal can be transmitted. Therefore, in the wireless terminal device, it is possible to avoid that the training signal cannot be correctly received due to a frequency collision, and an effect of realizing an early recovery of the wireless link between the wireless terminal device and the base station is expected. it can.

The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is a diagram showing an outline of a wireless communication system according to a first embodiment. 3 is a functional block diagram of a first base station according to Embodiment 1. FIG. 3 is a functional block diagram of a first radio terminal apparatus according to Embodiment 1. FIG. 3 is a hardware configuration diagram of a first base station according to Embodiment 1. FIG. 2 is a hardware configuration diagram of a first wireless terminal apparatus according to Embodiment 1. FIG. 3 is a sequence diagram showing an operation of the radio communication system according to Embodiment 1. FIG. 3 is a sequence diagram showing an operation of the radio communication system according to Embodiment 1. FIG. It is a figure which shows the spatial path | route in communication with a base station and a radio | wireless terminal apparatus. It is a figure which shows the example of the correspondence of the transmission direction of the training signal which each base station which concerns on Embodiment 1 transmits, transmission time, and transmission frequency. 6 is a diagram illustrating an operation of the first wireless terminal device in initial training of the wireless communication system according to Embodiment 1. FIG. 6 is a diagram showing an example of an antenna setting pair candidate list generated by initial training of the wireless communication system according to Embodiment 1. FIG. It is a figure which shows antenna setting ID of the training signal for initial learning which each base station which concerns on Embodiment 1 transmits. 6 is a diagram illustrating an example of radio link recovery antenna setting information regarding the first radio terminal apparatus according to Embodiment 1. FIG. 6 is a flowchart showing an operation of determining antenna settings of training signals transmitted from each base station according to Embodiment 1 for each TDM time slot. FIG. 6 is a diagram illustrating an antenna setting ID of a training signal transmitted by each base station in the wireless link recovery process of the wireless communication system according to the first embodiment. 6 is a diagram showing an example of radio link recovery antenna setting information regarding the first radio terminal apparatus according to Embodiment 2. FIG. 10 is a flowchart showing an operation for determining an antenna setting of a training signal transmitted by each base station according to Embodiment 2 for each TDM time slot. FIG. 12 is a diagram illustrating an antenna setting ID of a training signal transmitted by each base station in a wireless link recovery process of the wireless communication system according to the second embodiment. FIG. 11 is a diagram showing an outline of a wireless communication system according to a third embodiment. FIG. 10 is a diagram illustrating an example of radio link recovery antenna setting information regarding the second wireless terminal device according to the third embodiment. FIG. 10 is a diagram illustrating an antenna setting ID of a training signal transmitted by each base station in a wireless link recovery process of the wireless communication system according to the third embodiment. FIG. 10 is a diagram illustrating an example of radio link recovery antenna setting information regarding the first wireless terminal device according to the fourth embodiment. FIG. 10 is a diagram illustrating an example of radio link recovery antenna setting information regarding the second wireless terminal device according to the fourth embodiment. FIG. 10 is a diagram illustrating an antenna setting ID of a training signal transmitted by each base station in a radio link recovery process of a radio communication system according to a fourth embodiment. It is a figure which shows antenna setting ID of the training signal which each base station transmits as a comparative example with FIG. 24 which concerns on this Embodiment 4. FIG.

<Embodiment 1>
<Configuration>
FIG. 1 is a diagram showing an outline of the wireless communication system according to the first embodiment. As shown in FIG. 1, the wireless communication system includes first to

third base stations

101, 102, and 103, and first wireless terminals that can wirelessly communicate with first to

third base stations

101, 102, and 103. A device 201 is provided. The first to

third base stations

101, 102, 103 can communicate with each other via the wired network 50.

In the first embodiment and the second embodiment, the radio link recovery process of one radio terminal device (that is, the first radio terminal device 201) will be described. The case where the radio link recovery processing of two radio terminal apparatuses (namely, the first and second radio terminal apparatuses 201 and 202) is performed simultaneously will be described in

Embodiments

3 and 4 with reference to FIG. The second wireless terminal device 202 is not shown.

In this specification, when referring to a general base station that is not specified as the first to

third base stations

101, 102, 103, it is simply described as “base station”. Further, when referring to a general wireless terminal device that is not specified by the first and second

wireless terminal devices

201 and 202, it is simply described as “wireless terminal device”.

FIG. 2 is a functional block diagram of the first base station 101. Note that the configuration of the second and

third base stations

102 and 103 is the same as that of the first base station 101, and thus the description thereof is omitted. As shown in FIG. 2, the base station 101 includes a transmission / reception unit 10, an inter-base station communication unit 15, a control unit 16, a storage unit 17, a degradation detection unit 18, and a radio link recovery antenna setting information generation unit 19. With. The transmission / reception unit 10 includes a transmission antenna 11, a reception antenna 12, a transmission unit 13, and a reception unit 14.

The transmission / reception unit 10 can change the directivity of the transmission beam and the reception beam used for wireless communication with the wireless terminal device. The transmission antenna 11 can control the directivity of the transmission beam. The reception antenna 12 can control the directivity of the reception beam. The transmission unit 13 modulates transmission data. The receiving unit 14 demodulates received data. The inter-base station communication unit 15 communicates with other base stations including the second and

third base stations

102 and 103 via the wired network 50.

The control unit 16 controls the directivity of the transmission beam and the reception beam by changing the antenna setting of the transmission / reception unit 10. The radio link recovery antenna setting information generation unit 19 generates radio link recovery antenna setting information to be described later. The storage unit 17 stores radio link recovery antenna setting information. The deterioration detection unit 18 detects communication interruption or communication quality deterioration in wireless communication with the wireless terminal device.

FIG. 3 is a functional block diagram of the first wireless terminal device 201. As illustrated in FIG. 3, the first wireless terminal device 201 includes a transmission / reception unit 20, a control unit 25, an antenna setting pair candidate list generation unit 26, and an antenna setting pair determination unit 27. The transmission / reception unit 20 includes a transmission antenna 21, a reception antenna 22, a transmission unit 23, and a reception unit 24.

The transmission / reception unit 20 can change the directivity of the transmission beam and the reception beam used for wireless communication with the base station. The transmission antenna 21 can control the directivity of the transmission beam. The reception antenna 22 can control the directivity of the reception beam. The transmission unit 23 modulates transmission data. The receiving unit 24 demodulates received data.

The control unit 25 controls the directivity of the transmission beam and the reception beam by changing the antenna setting of the transmission / reception unit 20. The antenna setting pair candidate list generation unit 26 generates an antenna setting pair candidate list, which will be described later, based on reception of the training signal transmitted from the base station. The antenna setting pair determination unit 27 determines an antenna setting pair used for communication with the base station from the antenna setting pair candidate list.

FIG. 4 is a hardware configuration diagram of the first base station 101. Since the hardware configuration of the second and

third base stations

102 and 103 is the same as that of the first base station 101, description thereof is omitted. As shown in FIG. 4, the functions of the transmission / reception unit 10, the control unit 16, and the deterioration detection unit 18 of the first base station 101 are realized by a processing circuit HW16. Even if the processing circuit HW16 is dedicated hardware, a CPU (Central Processing Unit, a central processing unit, a processing unit, a processing unit, a microprocessor, a microcomputer, a processor, and a DSP that execute a program stored in the memory HW17 Say).

When the processing circuit HW16 is dedicated hardware, the processing circuit HW16 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. . Each function of the transmission / reception unit 10, the control unit 16, and the deterioration detection unit 18 may be realized by an individual processing circuit, or the functions of the respective units may be collectively realized by the processing circuit HW16.

When the processing circuit HW16 is a CPU, the functions of the transmission / reception unit 10, the control unit 16, and the deterioration detection unit 18 are realized by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in the memory HW17. The processing circuit HW16 implements the functions of the respective units by reading and executing the program stored in the memory HW17. Moreover, it can be said that these programs are what makes a computer perform the procedure and method of the transmission / reception part 10, the control part 16, and the deterioration detection part 18. FIG. Here, the memory HW17 is, for example, a nonvolatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD, etc. All storage media are applicable.

In addition, about each function of the transmission / reception part 10, the control part 16, and the deterioration detection part 18, a part may be implement | achieved by exclusive hardware and a part may be implement | achieved by software or firmware. For example, the function of the transmission / reception unit 10 is realized by a processing circuit as dedicated hardware, and the processing circuit HW16 reads and executes a program stored in the memory HW17 for the control unit 16 and the deterioration detection unit 18 The function can be realized.

As described above, the processing circuit HW16 can realize the above-described functions by hardware, software, firmware, or a combination thereof.

Further, as shown in FIG. 4, the function of the inter-base station communication unit 15 of the first base station 101 is realized by the inter-base station communication circuit HW15. The inter-base station communication circuit HW15 can realize the function of the inter-base station communication unit 15 by hardware, software, firmware, or a combination thereof, similarly to the processing circuit HW16 described above. As shown in FIG. 4, the function of the storage unit 17 of the first base station 101 is realized by a storage device HW18. The storage device HW18 corresponds to any storage medium like the memory HW17 described above.

FIG. 5 is a hardware configuration diagram of the first wireless terminal device 201. As shown in FIG. 5, each function of the transmission / reception unit 10, the control unit 25, the antenna setting pair candidate list generation unit 26, and the antenna setting pair determination unit 27 of the first wireless terminal device 201 is realized by a processing circuit HW25. . Even if the processing circuit HW25 is dedicated hardware, a CPU (Central Processing Unit, a central processing unit, a processing unit, a processing unit, a microprocessor, a microcomputer, a processor, and a DSP that execute a program stored in the memory HW26 Say).

When the processing circuit HW25 is dedicated hardware, the processing circuit HW25 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. . Each function of the transmission / reception unit 20, the control unit 25, the antenna setting pair candidate list generation unit 26, and the antenna setting pair determination unit 27 may be realized by individual processing circuits, or the functions of the respective units are collectively performed by the processing circuit HW25. It may be realized.

When the processing circuit HW25 is a CPU, the functions of the transmission / reception unit 20, the control unit 25, the antenna setting pair candidate list generation unit 26, and the antenna setting pair determination unit 27 are realized by software, firmware, or a combination of software and firmware. . Software and firmware are described as programs and stored in the memory HW26. The processing circuit HW25 reads out and executes the program stored in the memory HW26, thereby realizing the function of each unit. These programs can also be said to cause the computer to execute the procedures and methods of the transmission / reception unit 20, the control unit 25, the antenna setting pair candidate list generation unit 26, and the antenna setting pair determination unit 27. Here, the memory HW26 is, for example, a nonvolatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD, etc. All storage media are applicable.

In addition, about each function of the transmission / reception part 20, the control part 25, the antenna setting pair candidate list production | generation part 26, and the antenna setting pair determination part 27, a part is implement | achieved by exclusive hardware and a part is implement | achieved by software or firmware. You may do it. For example, the function of the transmission / reception unit 20 is realized by a processing circuit as dedicated hardware, and the processing circuit HW25 is stored in the memory HW26 for the control unit 25, the antenna setting pair candidate list generation unit 26, and the antenna setting pair determination unit 27. The function can be realized by reading and executing the stored program.

As described above, the processing circuit HW25 can realize the above-described functions by hardware, software, firmware, or a combination thereof.

<Operation>
6 and 7 are sequence diagrams showing the operation of the radio communication system according to the first embodiment. In preparation for the first wireless terminal apparatus 201 and the base station to start wireless communication using the antenna beamforming technique, the first wireless terminal apparatus 201 performs initial training shown in step S201 of FIG. The details of the initial training will be described below. In order to make the description easy to understand, the description will be made on the assumption that the base station is only the first base station for a while.

FIG. 8 is a diagram illustrating an example of a spatial path in communication between the first base station 101 and the first wireless terminal device 201. The purpose of the initial training will be described with reference to FIG. In the example of FIG. 8, a spatial path 310 and a spatial path 311 that can communicate between the first base station 101 and the first wireless terminal device 201 exist. The directivity of each antenna of the first base station 101 and the first wireless terminal device 201 adopting the antenna beamforming technology can be controlled by setting. Communication is possible by setting each antenna to transmit and receive in the direction of the spatial path 310 or the spatial path 311. When communicating using the spatial path 310, the antenna of the first base station 101 is set to have directivity of the transmission / reception beam 320, and the antenna of the first wireless terminal device 201 is the transmission / reception beam 321. It is necessary to make settings so as to achieve directivity. Similarly, when communicating using the spatial path 311, the antenna of the first base station 101 is set to have directivity of the transmission / reception beam 322, and the antenna of the first wireless terminal device 201 is transmitted / received. It is necessary to make settings so that the directivity of the beam 323 is obtained.

As described above, it is necessary to search for a combination of antenna settings in which the first base station 101 and the first wireless terminal device 201 can communicate, and therefore, initial training is performed. Assuming that the number of antenna settable patterns in the first base station 101 is N and the number of antenna settable patterns in the first wireless terminal apparatus 201 is M, there are N × M combinations of antenna settings. The purpose of the initial training is to create a list (that is, an antenna setting pair candidate list, which will be described later) by searching so as to cover N × M ways.

Next, the procedure for initial training will be explained. In Non-Patent Document 2, the base station transmits a training signal in all directions by TDM (time multiplexing) and FDM (frequency multiplexing), and the wireless terminal device has a cycle in which the base station transmits the training signal in all directions. Shows a method for exhaustively searching by changing the antenna setting of the wireless terminal device.

The behavior of the first to

third base stations

101, 102, 103 in the initial training will be described. Each of the first to

third base stations

101, 102, 103 does not need to be aware of when the wireless terminal device is performing initial training, and trains so that an arbitrary wireless terminal device can be connected at an arbitrary timing. Always send signals.

FIG. 9 shows an example of a correspondence relationship between the transmission direction, transmission time, and transmission frequency of the training signal transmitted by the first base station 101 as a representative of a plurality of base stations. The first base station 101 comprehensively transmits training signals in all directions by TDM (time multiplexing) and FDM (frequency multiplexing). The upper part of FIG. 9 shows the time change in the transmission direction of the training signal. Here, the transmission direction is expressed in a two-dimensional space, but actually the transmission direction changes in a three-dimensional space. The lower part of FIG. 9 shows the transmission time and transmission frequency assignment of the training signal. The same pattern in the upper part and the lower part of FIG.

In FIG. 9, for example, the training signal 431 corresponds to the training signal transmitted at the frequency 421 at the time 411, the training signal 432 corresponds to the training signal transmitted at the frequency 422 at the time 411, and the training signal 433 is the time 411. Corresponding to the training signal transmitted at frequency 423, training signal 434 corresponds to the training signal transmitted at frequency 424 at time 411.

In the upper part of FIG. 9, the transmission direction of the training signal is changed while changing the directivity of the antenna little by little. This shows how the training signal is transmitted so as to cover all directions. . The training signal may be transmitted so as to cover all directions, and it is not always necessary to transmit the training signal while changing the rotation, and the transmission direction may be selected at random.

In FIG. 9, the number of FDM multiplexing is four, but this is an example, and the number of FDM multiplexing may be other than four. Since the direction in which transmission can be performed simultaneously can be increased according to the number of FDM multiplexes, the initial training can be completed earlier when the number of FDM multiplexes is large. However, whether or not a training signal of a plurality of frequencies can be received simultaneously depends on the capability of the wireless terminal device.

Next, an initial training procedure for the first wireless terminal apparatus 201 will be described. FIG. 10 is a diagram illustrating an operation of the first wireless terminal device 201 in the initial training. In FIG. 10, the passage of time is shown from left to right. In FIG. 10, the number of antenna setting patterns of the first wireless terminal device 201 is M, the number of TDM time slots required for the first base station 101 to transmit a training signal in all directions is N, and the first base station 101 Let K be the number of FDM multiplexes that can simultaneously transmit training signals. In FIG. 10, block 501 corresponds to the antenna setting of the first wireless terminal apparatus 201, and block 502 corresponds to the antenna setting of the first base station 101.

The upper part of FIG. 10 shows a schematic image of the reception direction corresponding to the antenna setting of the first wireless terminal apparatus 201, and the lower part of FIG. 10 shows a schematic image of the transmission direction corresponding to the antenna setting of the first base station 101. Is shown. As illustrated in FIG. 10, the first wireless terminal device 201 realizes an exhaustive search by changing the antenna setting at a cycle in which the first base station 101 transmits a training signal in all directions.

The antenna setting pair candidate list generation unit 26 of the first wireless terminal apparatus 201 measures the reception level of the training signal for each FDM frequency for each TDM time slot, and determines that the training signal has been successfully received if the threshold is exceeded. To do. When the training signal is successfully received, the first wireless terminal apparatus 201 can determine the combination of antenna settings that can be communicated.

The antenna setting of the first base station 101 can be obtained indirectly by a combination of the time and frequency at which the first wireless terminal apparatus 201 receives the training signal. The antenna setting of the first wireless terminal device 201 is self-evident because it is the terminal itself.

The combination of antenna settings that can be communicated between the first base station 101 and the first wireless terminal device 201 obtained in this way is referred to as an antenna setting pair (Beam Pair). The antenna setting pairs are listed and held in the first wireless terminal device 201. The listed antenna setting pairs are referred to as an antenna setting pair candidate list.

After completing the exhaustive search, the antenna setting pair determination unit 27 of the first wireless terminal device 201 selects the antenna setting pair having the best reception level from the antenna setting pair candidate list as the antenna setting pair to be used for communication. Record it. This is the initial training.

As in the first embodiment, even when there are a plurality of base stations, the initial training procedure is the same. However, there are two caveats. As a first precaution, when there are a plurality of base stations, it is necessary to include identification information in the training signal so that the first wireless terminal apparatus 201 can identify the base station. The first wireless terminal device 201 must also identify the base station in the training signal reception process, and record the antenna setting pair information including the identification information of the base station.

As a second precaution, the number of TDM time slots required for a base station to transmit a training signal in all directions may vary from base station to base station. In order to search exhaustively for all base stations, the period for changing the antenna setting of the first wireless terminal apparatus 201 needs to be matched to the base station with the largest number of TDM time slots.

As described above, the first wireless terminal device 201 completes the initial training (step S201). Assume that a total of seven spatial paths (ie, a total of seven antenna setting pairs) shown in FIG. 1 are found as a result of the initial training. FIG. 11 is a diagram illustrating an antenna setting pair candidate list generated in the initial training. In FIG. 11, the antenna setting pair with the antenna setting pair ID = 0 corresponds to the spatial path 105 in FIG. The antenna setting pair with the antenna setting pair ID = 1 corresponds to the spatial path 106 in FIG. The antenna setting pair with the antenna setting pair ID = 2 corresponds to the spatial path 107 in FIG. The antenna setting pair with the antenna setting pair ID = 3 corresponds to the spatial path 108 in FIG. The antenna setting pair with the antenna setting pair ID = 4 corresponds to the spatial path 109 in FIG. The antenna setting pair with the antenna setting pair ID = 5 corresponds to the spatial path 110 in FIG. The antenna setting pair with the antenna setting pair ID = 6 corresponds to the spatial path 111 in FIG. In FIG. 10, cell ID = 0 indicates the first base station 101. Cell ID = 1 indicates the second base station 102. Cell ID = 2 indicates the third base station 103.

Suppose that the first wireless terminal apparatus 201 has selected the antenna setting pair ID = 1, that is, the spatial path 106 as the antenna setting pair for communication. At this time, it is assumed that the shield 112 in FIG. 1 does not exist.

After the initial training (step S201), the first wireless terminal device 201 sets the antenna setting pair candidate list (FIG. 11) and the communication antenna setting pair ID = 1, which are the results of the initial training, to the first base station 101. (Step S202).

After step S202 of FIG. 6, the first wireless terminal device 201 refers to the wireless terminal device antenna setting ID = 20 corresponding to the communication antenna setting pair ID = 1, and sets it to its own antenna (step S203). .

The first base station 101 receives the antenna setting pair candidate list (FIG. 11) and the communication antenna setting pair ID = 1 from the first wireless terminal device 201 (step S215). Then, the first base station 101 refers to the base station antenna setting ID = 120 corresponding to the communication antenna setting pair ID = 1 and sets it to its own antenna (step S216).

When the first wireless terminal device 201 and the first base station 101 complete antenna setting with each other, wireless communication is possible using the spatial path 106 (steps S204 and S217).

Next, when the first wireless terminal apparatus 201 and the first base station 101 communicate with each other using the spatial path 106, the shielding object 112 appears, the communication quality deteriorates, or the communication is interrupted. (Step S205 in FIG. 7). When the shielding object 112 is generated and communication is deteriorated or interrupted, the deterioration detecting unit 18 of the first base station 101 detects deterioration of communication quality (step S218). Then, the first base station 101 notifies the first wireless terminal device 201 of the deterioration of communication quality, and proceeds to a processing procedure for recovering the wireless link (step S218).

The first wireless terminal device 201 receives a notification of communication quality deterioration from the first base station 101, or moves to a processing procedure for recovering a wireless link when it detects the deterioration of communication quality itself. (Step S206).

Next, the processing procedure for recovering the wireless link will be described. In order to recover the wireless link, the wireless terminal device needs to receive the training signal, and the reception level of the received training signal needs to be equal to or higher than the threshold value. According to Patent Document 1, a base station preferentially selects a base station antenna setting ID included in an antenna setting pair candidate list, performs antenna setting, transmits a training signal, and a wireless terminal device performs training from all directions. Set the antenna so that the signal can be received. As a result, the wireless terminal device can quickly receive the training signal, which indicates that there is an effect of shortening the time until the wireless link is restored.

By the way, two words are defined to make the explanation easy to understand. The training signal transmitted from the base station as shown in FIG. 9 and FIG. 10 for the purpose of initial training will be referred to as initial learning training signal. A training signal transmitted for the purpose of radio link recovery is referred to as a radio link recovery training signal. The training signal for initial learning and the training signal for radio link recovery are both radio signals that have the same physical properties with only different antenna settings (transmission direction). To do.

In Patent Document 1, only one-to-one communication is considered, that is, it is assumed that there is only one base station. In the example of FIG. 1, all three

spatial paths

105, 106, and 107 between the first base station 101 and the first wireless terminal device 201 are blocked by the shield 112. Therefore, it is obvious that even if only the first base station 101 performs the processing procedure for recovering the radio link, the effect of shortening the time until the radio link is recovered cannot be expected.

In the situation as shown in FIG. 1, it is proposed in Non-Patent Document 1 that it is effective to attempt recovery of a radio link in cooperation with a base station adjacent to a base station whose communication quality has deteriorated. In Non-Patent Document 1, when a base station communicating with a wireless terminal apparatus detects deterioration in communication quality, it transmits a wireless link recovery request to an adjacent base station. When the adjacent base station receives the radio link recovery request, the base station antenna setting ID included in the antenna setting pair candidate list is preferentially selected to perform antenna setting, and transmits a radio link recovery training signal.

As described above, a method for recovering a radio link in cooperation with a plurality of base stations has been proposed. In the radio link recovery procedure, the antenna setting of the radio terminal apparatus is omnidirectional, that is, a setting that can be received from all directions. It is said. Therefore, when a plurality of base stations transmit radio link recovery training signals simultaneously and at the same frequency, there is a problem that the respective training signals interfere with each other and are input to the reception circuit of the radio terminal apparatus.

In the first embodiment, the base station (that is, the first base station 101) that detects the communication interruption or degradation in the radio link recovery procedure generates radio link recovery antenna setting information (step S220). Then, the base station 101 includes the radio link recovery antenna setting information in the radio link recovery request and transmits it to the second and third base stations 102 and 103 (step S221). Each of the first to

third base stations

101, 102, 103 transmits a radio link recovery training signal based on the radio link recovery antenna setting information (steps S222, S223, S224). With the above control, it is possible to preferentially try the antenna settings included in the antenna setting pair candidate list while avoiding the above-described problem of interference with the training signal, which is effective for early recovery of the radio link. Detailed procedures and effects of radio link recovery in the first embodiment will be described below.

FIG. 12 is a diagram showing antenna setting IDs of training signals for initial learning transmitted from the first to

third base stations

101, 102, and 103 in a certain period. A numeric string 700 in FIG. 12 is a frame number that increases by 1 in synchronization with the TDM time slot, and is used as information indicating time in wireless communication. Tables 701, 702, and 703 in FIG. 12 indicate antenna setting IDs corresponding to the FDM frequencies of the frames in the

base stations

101, 102, and 103, respectively.

The vertical axis in FIG. 12 represents the frequency. Each

frequency

711, 721, 731 corresponding to FDM # 0 is the same frequency. Each

frequency

712, 722, 732 corresponding to FDM # 1 is the same frequency. Each

frequency

713, 723, 733 corresponding to FDM # 2 is the same frequency. Each

frequency

714, 724, 734 corresponding to FDM # 3 is the same frequency. Further, the number of FDM multiplexing is set to 4 in each of the first to

third base stations

101, 102, and 103.

When the shielding object 112 in FIG. 1 appears immediately before the frame number = 168 (time 740) in FIG. 12 and the deterioration detection unit 18 of the first base station 101 detects a disruption of wireless communication or quality deterioration, The base station 101 proceeds to a process for generating radio link recovery antenna setting information (step S220).

FIG. 13 is a diagram illustrating an example of radio link recovery antenna setting information related to the first radio terminal device 201 generated in step S220. The radio link recovery antenna setting information includes time information serving as a reference for the time at which transmission of the radio link recovery training signal is started, and an antenna setting order list indicating the antenna setting order.

The antenna setting order list is a list of data in which a setting order, a cell ID, and a base station antenna setting ID are paired. The antenna setting order list [X] is defined as indicating data of setting order = X in the antenna setting order list.

The time information included in the radio link recovery antenna setting information in FIG. 12 is, for example, a head frame number indicating a time at which transmission of a radio link recovery training signal is started. A procedure for generating the first frame number will be described. The radio link recovery antenna setting information generation unit 19 of the first base station 101 that has detected the degradation of the quality of the radio communication, at the current time, the time taken to generate the radio link recovery antenna setting information, and the radio link recovery request A time is calculated by adding the time required for transmission / reception, the time required for the antenna setting process of the training signal, and the time for one TDM time slot. Then, the radio link recovery antenna setting information generation unit 19 calculates a frame number corresponding to the TDM time slot including the calculated time, and sets this frame number as the first frame number. In FIG. 12, it is assumed that the top frame number = 168 is calculated in the same manner as FIG.

A procedure for generating the antenna setting order list included in the radio link recovery antenna setting information of FIG. 13 will be described. Here, for the simplest implementation example, it is assumed that the FDM multiplexing numbers of the training signals of the first to

third base stations

101, 102, and 103 are equal to each other. The radio link recovery antenna setting information generation unit 19 of the first base station 101 uses the antenna setting pair ID in use from the antenna setting pair candidate list (FIG. 11), that is, the antenna setting pair ID = What is excluded from 1 may be an antenna setting order list.

The antenna setting order list in FIG. 12 is generated based on the antenna setting pair candidate list in FIG. The antenna setting order list [0] is information generated from the antenna setting pair ID = 0 in FIG. The antenna setting order list [1] is information generated from the antenna setting pair ID = 2 in FIG. The antenna setting order list [2] is information generated from the antenna setting pair ID = 3 in FIG. 11, and the antenna setting order list [3] is information generated from the antenna setting pair ID = 4 in FIG. is there. The antenna setting order list [4] is information generated from the antenna setting pair ID = 5 in FIG. The antenna setting order list [5] is information generated from the antenna setting pair ID = 6 in FIG.

The radio link recovery antenna setting information generated as described above is held in the storage area (that is, the storage unit 17) inside the first base station 101. Further, the radio link recovery antenna setting information is included in the radio link recovery request and transmitted to each of the base stations described in the antenna setting order list (step S221). That is, one base station 101 transmits a radio link recovery request to each of the second and third base stations 102 and 103 (step S221). Each of the second and

third base stations

102 and 103 holds the radio link recovery antenna setting information included in the received radio link recovery request in the internal storage area (that is, the storage unit 17).

Next, a method will be described in which each of the first to

third base stations

101, 102, 103 determines the antenna setting using the radio link recovery antenna setting information. FIG. 14 is a flowchart illustrating an operation in which each of the first to

third base stations

101, 102, and 103 determines an antenna setting of a training signal to be transmitted for each TDM time slot. Hereinafter, the operation of the first base station 101 will be described with reference to FIG. 14, but the same applies to the operations of the second and

third base stations

102 and 103.

First, define the parameter FDM_index. FDM_index is an index corresponding to each frequency of FDM # 0 to FDM # 3 in FIG. FDM_index starts from 0 and increases by 1 for each iteration. In step S901 in FIG. 14, FDM_index is set to 0.

Next, the contents of the repetition processing for the previous FDM multiplexing will be described. First, the first base station 101 determines whether or not it holds valid radio link recovery antenna setting information (step S902). Here, if the current frame number is equal to or greater than the first frame number included in the radio link recovery antenna setting information, it is determined that the radio link recovery antenna setting information is valid.

If it is determined in step S902 that valid radio link recovery antenna setting information is held, the process proceeds to radio link recovery antenna setting derivation (step S906). On the other hand, if it is not determined that the effective radio link recovery antenna setting information is held, the process proceeds to the initial learning antenna setting process (step S903).

The antenna learning process for initial learning in step S903 is a process for determining antenna settings for initial training. For the purpose of performing exhaustive antenna settings in the initial training, in this embodiment, the antenna setting ID is increased by one, for example, as shown in FIG.

After the initial learning antenna determination process, 1 is added to the FDM_index (step S904). Then, the base station 101 determines whether or not the FDM_index is smaller than the FDM multiplexing number (step S905). If the FDM_index is smaller than the FDM multiplexing number, the process returns to step S901 and the process is repeated. On the other hand, if FDM_index is equal to the FDM multiplexing number, the iterative process is terminated.

In derivation of the radio link recovery antenna setting in step S906, the value calculated by the following equation (1) is held in the parameter Recovery_Index.

(First frame number−current frame number) × FDM multiplexing number + FDM_Index (1)
Next, it is determined whether the target cell is the own cell (step S907). In step S907, when the following conditional expression (2) is satisfied, the process proceeds to radio link recovery antenna determination processing (step S913).

Cell ID of antenna setting order list [Recovery_Index] = ID of own cell (2)
If the conditional expression (2) is not satisfied, the process proceeds to the initial learning antenna determination process (step S908).

In the radio link recovery antenna determination process in step S913, the base station antenna setting ID of the antenna setting order list [Recovery_Index] is formally determined as the antenna setting ID. The determined antenna setting ID is used for antenna setting of a training signal transmitted at any frequency of FDM # 0 to FDM # 3 corresponding to the FDM_Index of the current frame. Following the radio link recovery antenna determination process in step S913, it is determined whether or not the radio link recovery antenna setting information is to be discarded (step S911).

Next, the initial learning antenna determination process in step S908 will be described. The contents of the initial learning antenna determination process are the same as those of the initial learning antenna determination process in step S903.

After the initial learning antenna determination process in step S908, it is determined whether or not the determined antenna setting ID overlaps with the antenna setting ID of the own cell in the antenna setting order list (step S909). The purpose of performing step S909 is to avoid interference if the antenna setting ID determined in the initial learning antenna determination process is included in the antenna setting order list, and this is avoided. In step S909, if there is data in the antenna setting order list that satisfies the condition that the cell ID is that of the own cell and the base station antenna setting ID is equal to the antenna setting ID determined in step S908. Then, it is determined that there is duplication, and the process proceeds to training signal stop (step S910). On the other hand, if there is no data satisfying this condition in the antenna setting order list, it is determined that there is no duplication, and the process proceeds to step S911.

In step S910, when the training signal is stopped, the base station 101 determines not to transmit a training signal at a frequency corresponding to the FDM_Index of the current frame. Although the wireless band is wasted, priority is given to avoiding interference, so such a determination is made.

In step S911, it is determined whether or not the radio link recovery antenna setting information is to be discarded. The first base station 101 determines whether or not the condition of the number of data in the antenna setting order list = Recovery_Index + 1 is satisfied. When this condition is satisfied, the base station 101 determines to discard the radio link recovery antenna setting information, and proceeds to the antenna setting information discarding process (step S912). On the other hand, if this condition is not satisfied, the process moves to step S904.

In the antenna setting information discarding process in step S912, the radio link recovery antenna setting information stored in the storage area inside the first base station 101 is deleted. After the antenna setting information discarding process, the process proceeds to step S904.

The above is the description of the process for determining the antenna setting of the training signal transmitted for each TDM time slot.

FIG. 15 is a diagram illustrating antenna setting IDs of training signals transmitted from the first to

third base stations

101, 102, and 103 in the radio link recovery processing according to the first embodiment. That is, the antenna setting ID of the training signal is corrected as shown in FIGS.

As shown in FIG. 15, the first base station 101 corrects the antenna setting ID from 8 to 100 at frame number = 168 and transmits a training signal for radio link recovery at the frequency of FDM # 0. In addition, the first base station 101 corrects the antenna setting ID from 9 to 150 in the frame number = 168 and transmits a training signal for radio link recovery at the frequency of FDM # 1.

The second base station 102 corrects the antenna setting ID from 58 to 80 in the frame number = 168 and transmits the training signal for radio link recovery at the frequency of FDM # 2. In addition, the second base station 102 corrects the antenna setting ID from 9 to 120 in the frame number = 168 and transmits a training signal for radio link recovery at the frequency of FDM # 3.

The third base station 103 corrects the antenna setting ID from 112 to 210 in the frame number = 169 and transmits a training signal for radio link recovery at the frequency of FDM # 0. Also, the third base station 103 corrects the antenna setting ID from 113 to 220 at the frame number = 169, and transmits a radio link recovery training signal at the frequency of FDM # 4.

Conventionally, when performing radio link recovery, multiple base stations select antenna settings at any time and at any frequency, so interference occurs when antenna settings for radio link recovery are made at the same time and at the same frequency. May occur. When interference occurs, the wireless terminal device cannot receive a training signal as expected. If the radio link recovery training signal cannot be received due to the occurrence of interference, it will wait until the initial learning training signal can be received, and at the longest, the radio link will be interrupted for the period in which the initial learning training signal is comprehensively transmitted. It will be.

In the first embodiment, since it is possible to avoid the transmission of the radio link recovery training signal at the same time and the same frequency, the first radio terminal apparatus 201 receives the radio link recovery training signal and The effect of restoring the wireless link can be expected.

In the first embodiment, the wireless communication system includes three base stations. However, the present invention is not limited to this as long as there are a plurality of base stations.

<Effect>
The radio communication system according to the first embodiment includes a plurality of base stations (that is, first to

third base stations

101, 102, 103) that can communicate with each other, and each of the plurality of base stations includes at least one base station. Wireless communication is possible with the wireless terminal device (that is, the first wireless terminal device 201), and at least one wireless terminal device can change the directivity of the transmission beam and the reception beam by changing the antenna setting. Each of the base stations includes a transmission / reception unit 10 that can change the directivity of the transmission beam and the reception beam, a deterioration detection unit 18 that detects communication interruption or deterioration of communication quality in wireless communication with the wireless terminal device, Radio link recovery antenna setting information generating unit 19 for generating link recovery antenna setting information, and storage unit for storing radio link recovery antenna setting information 7 and a control unit 16 that controls the directivity of the transmission beam and the reception beam by changing the antenna setting of the transmission / reception unit, and performs wireless communication with at least one wireless terminal device among a plurality of base stations. When the base station degradation detection unit 18 detects a radio communication interruption or communication quality degradation, the radio link recovery antenna setting information generation unit 19 of the base station that detects the radio communication interruption or degradation detects the antenna setting. Radio link recovery antenna setting information is generated based on the pair candidate list, and the antenna setting pair candidate list is an initial training for starting wireless communication between at least one wireless terminal device and any of a plurality of base stations. The antenna setting pair candidate list identifies the antenna setting of at least one wireless terminal device and the base station. The radio link recovery antenna setting information starts transmission of an antenna setting order list and a radio link recovery training signal. The time setting reference, and the antenna setting order list is a list that defines the order of the combination of the identification information for identifying the base station and the antenna setting of the base station identified by the identification information, The base station that detects the disruption or degradation of the radio communication transmits a radio link recovery request to each of the base stations described in the antenna setting order list, and the same radio link recovery request is transmitted to each of the transmitted radio link recovery requests. Includes radio link recovery antenna configuration information, and received the base station that transmitted the radio link recovery request and the radio link recovery request Based on the antenna setting order list and the time information, each transmitting / receiving unit 10 of the base station transmits the radio link recovery training signal at a timing at which the radio link recovery training signal is not simultaneously transmitted from a plurality of base stations at the same frequency. The transmitted radio link recovery training signal is a training signal transmitted with the antenna setting described in the antenna setting order list.

According to the radio communication system in the first embodiment, in the radio link recovery process, a plurality of base stations share the same antenna setting order list and the same time information. As a result, each of the plurality of base stations transmits the radio link at a timing at which the antenna setting training signal (that is, the radio link recovery training signal) described in the antenna setting order list is not simultaneously transmitted from the plurality of base stations at the same frequency. A recovery training signal can be transmitted. Therefore, in the wireless terminal device, it is possible to avoid that the training signal cannot be correctly received due to a frequency collision, and an effect of realizing an early recovery of the wireless link between the wireless terminal device and the base station is expected. it can.

In the radio communication system according to the first embodiment, the time information included in the radio link recovery antenna setting information is a head frame number indicating the time at which transmission of the radio link recovery training signal is started.

Therefore, each of the plurality of base stations transmits the radio link recovery training signal at a timing at which the radio link recovery training signal is not simultaneously transmitted from the plurality of base stations at the same frequency with the start frame number as a time reference. It becomes possible.

Further, in the wireless communication system according to the first embodiment, the radio link recovery antenna setting information generation unit 19 generates the antenna setting pair candidate when generating the radio link recovery antenna setting information based on the antenna setting pair candidate list. An antenna setting pair in which wireless communication is interrupted or communication quality is deteriorated is excluded from the list.

Therefore, the degradation of the communication quality is detected by generating the radio link recovery antenna setting information by excluding the antenna setting pair in which the wireless communication interruption or the degradation of the communication quality is detected from the antenna setting pair candidate list. It is possible to avoid the training signal being transmitted with the antenna setting. Therefore, the effect of realizing the recovery of the radio link earlier between the radio terminal device and the base station can be expected.

In addition, the wireless communication system according to the present embodiment further includes at least one wireless terminal device (that is, first wireless terminal device 201), and at least one wireless terminal device changes the directivity of the transmission beam and the reception beam. Possible transmitter / receiver 20, antenna setting pair candidate list generating unit 26 for generating an antenna setting pair candidate list in initial training, and an antenna used for communication with one of a plurality of base stations from the antenna setting pair candidate list An antenna setting pair determination unit 27 that determines a setting pair; and a control unit 25 that controls the directivity of the transmission beam and the reception beam by changing the antenna setting of the transmission / reception unit 20, and at least one wireless terminal device includes: Receive a communication quality degradation notification from a base station performing wireless communication among a plurality of base stations, or When the communication interruption or the communication quality deterioration is detected, the directivity of the reception beam of the transmission / reception unit 20 is changed to non-directional, and the antenna setting pair candidate list generation unit 26 adds the received radio link recovery training signal to the received radio link recovery training signal. Based on the updated antenna setting pair candidate list, the antenna setting pair determination unit 27 determines an antenna setting pair to be used for communication with any of the plurality of base stations from the updated antenna setting pair candidate list.

In the first embodiment, during the radio link recovery process, the radio terminal apparatus receives the radio link recovery training signal by setting the directivity of the reception beam to non-directional. In this Embodiment 1, it is possible to avoid that a training signal cannot be received correctly due to a frequency collision in a wireless terminal device, and early recovery of a wireless link between the wireless terminal device and a base station is possible. The effect to be realized can be expected.

<Embodiment 2>
In Embodiment 1, the radio link recovery training signal is transmitted once for each antenna setting. This is based on the premise that the first to

third base stations

101, 102, 103 and the first wireless terminal device 201 can simultaneously start the wireless link recovery process. However, when the first wireless terminal device 201 cannot receive the communication quality deterioration notification, this premise is not satisfied. In such a case, it is effective to repeatedly try to transmit a radio link recovery training signal. In the second embodiment, each of the first to

third base stations

101, 102, 103 repeatedly transmits a radio link recovery training signal.

In the second embodiment, the following changes (2A), (2B), and (2C) are performed with respect to the first embodiment. (2A) Repeated information is added to the radio link recovery antenna setting information. (2B) Repeated information generation processing is added to the generation of radio link recovery antenna setting information. (2C) In the radio link recovery process, a process of repeatedly transmitting a radio link recovery training signal is added.

The above (2A) will be described. FIG. 16 is a diagram illustrating an example of radio link recovery antenna setting information regarding the first radio terminal apparatus 201 according to the second embodiment. In Embodiment 2, repetitive information is added to the radio link recovery antenna setting information. The repetition information includes two information elements, a repetition period and a repetition count. The unit of the repetition period is the number of frames. In FIG. 16, for example, the repetition cycle = 4 and the number of repetitions = 2. In FIG. 16, the antenna setting order list and the top frame number are the same as those in FIG.

The above (2B) will be described. In the second embodiment, processing for determining the repetition period and the number of repetitions is added in the generation processing of the radio link recovery antenna setting information (step S220 in FIG. 7). The repetition period is determined to be a value equal to or greater than ROUNDUP (number of data in the antenna setting order list / number of FDM multiplexing). ROUNDUP (X) means rounding up the decimal part of X. The shorter the repetition period, the faster the time until radio link recovery. Also, the shorter the repetition period, the more difficult the transmission of the initial training signal is. The repetition period is determined in consideration of these.

The process for determining the number of repetitions may be determined in consideration of whether or not the communication quality degradation notification (step S219 in FIG. 7) has reached the wireless terminal device 200. Whether or not the communication quality degradation notification has reached the wireless terminal device 200 can be determined, for example, by whether or not an ACK response to the communication quality degradation notification has been obtained. When an ACK response is obtained from the first radio terminal apparatus 201, the first radio terminal apparatus 201 immediately moves to radio link recovery processing, and therefore the number of repetitions may be set to be small. If an ACK response cannot be obtained from the first wireless terminal device, the first wireless terminal device 201 may not yet move to the wireless link recovery process, so it is better to set a larger number of repetitions.

If the deterioration notification has not arrived at the first wireless terminal device 201, the repetition period and the number of repetitions may be determined so as to satisfy the following conditional expression (3).

Repetition cycle × number of repetitions ≧ communication quality monitoring cycle of wireless terminal device (3)
The above (2C) will be described. FIG. 17 is a flowchart illustrating an operation in which each of the first to

third base stations

101, 102, and 103 determines an antenna setting of a training signal to be transmitted for each TDM time slot. In FIG. 17, the contents of radio link recovery antenna setting derivation (step S906) are changed with respect to FIG. 14 of the first embodiment. Further, the content of the step of determining whether or not to discard the radio link recovery antenna setting information (step S911) is changed. Further, a step (step S1201) of determining whether to allocate a radio link recovery training signal to a frequency corresponding to the FDM_Index of the current frame is added between steps S906 and S907.

In derivation of the radio link recovery antenna setting in step S906, the value calculated by the following equation (4) is held in the parameter Recovery_Index.
(Result of Formula (1)) MOD (Repetition Period × FDM Multiplex Number) (4)
X MOD Y in equation (4) means a calculation symbol that returns a remainder obtained by dividing X by Y.

In step S1201, it is determined whether to allocate a radio link recovery training signal to a frequency corresponding to the FDM_Index of the current frame. When the following conditional expression (5) is satisfied, it is determined that a radio link recovery training signal is allocated. When the conditional expression (5) is not satisfied, it is determined that the initial learning training signal is assigned, and the process proceeds to the initial learning antenna determination process in step S903.

Recovery_Index <Number of data in the antenna setting order list (5)
In the step of determining whether or not to discard the radio link recovery antenna setting information in step S911, it is determined to be discarded when the following conditional expression (6) is satisfied, and the process proceeds to the antenna setting information discarding process in step S912. . When the conditional expression (6) is not satisfied, the process proceeds to the end point (904) of the iterative process for the FDM multiplexing number.

Repetition cycle × number of repetitions × FDM multiplexing number = (result of equation (1)) + 1 (6)
FIG. 18 is a diagram illustrating antenna setting IDs of training signals transmitted from the first to

third base stations

101, 102, and 103 in the radio link recovery processing according to the second embodiment. Comparing FIG. 18 to FIG. 15 of the first embodiment, in FIG. 18, the radio link recovery training signal for each antenna setting is repeatedly transmitted twice.

As shown in FIG. 18, the first base station 101 transmits a radio link recovery training signal at a frequency of FDM # 0 with an antenna setting ID = 100 at frame number = 168 and frame number = 172. Also, the first base station 101 transmits a radio link recovery training signal at the frequency of FDM # 1 with the antenna setting ID = 150 at frame number = 168 and frame number = 172.

The second base station 102 transmits the radio link recovery training signal at the frequency of FDM # 2 with the antenna setting ID = 80 in the frame number = 168 and the frame number = 172. Also, the second base station 102 transmits a radio link recovery training signal at the frequency of FDM # 3 with the antenna setting ID = 120 in the frame number = 168 and the frame number = 172.

The third base station 103 transmits a training signal for radio link recovery at the frequency of FDM # 0 with the antenna setting ID = 210 at frame number = 169 and frame number = 173. Also, the third base station 103 transmits a radio link recovery training signal at the frequency of FDM # 1 with the antenna setting ID = 220 in the frame number = 169 and the frame number = 173.

<Effect>
In the radio communication system according to the second embodiment, the radio link recovery antenna setting information further includes a repetition period and the number of repetitions, and a base station (for example, the first base station) that detects the interruption or deterioration of the radio communication is included. The station 101) transmits a communication quality degradation notification to at least one radio terminal device (ie, the first radio terminal device 201). When the base station receives a response to the communication quality degradation notification, the station 101) The antenna setting information generation unit 19 sets a smaller number of repetitions, and when the base station does not receive a response to the communication quality degradation notification, the radio link recovery antenna setting information generation unit 19 sets a larger number of repetitions. The transmitting / receiving units 10 of the base station that transmitted the radio link recovery request and the base station that received the radio link recovery request For each antenna configuration described in Na setting order list, and transmits the number of times repeatedly at a repetition cycle training signals for radio link recovery.

In Embodiment 2, since the first to

third base stations

101, 102, and 103 repeatedly transmit the radio link recovery training signal, the probability that the first radio terminal apparatus 201 can receive the training signal is increased. . That is, it is possible to further reduce the time required for radio link recovery. Further, the radio link recovery training signal is excessively repeated by adjusting the number of repetitions of the radio link recovery training signal according to whether or not the first wireless terminal device 201 has been notified of the communication quality deterioration notification. There is also an advantage of avoiding sending.

<Embodiment 3>
FIG. 19 is a diagram illustrating an outline of the wireless communication system according to the third embodiment. The wireless communication system according to the third embodiment further includes a second wireless terminal device 202 in addition to the first wireless terminal device 201. Since the configuration of the second wireless terminal device 202 is the same as that of the first wireless terminal device 201 (FIGS. 3 and 5), description thereof is omitted.

In the third embodiment, the first base station 101 communicates with the first radio terminal apparatus 201 and the second radio terminal apparatus 202, and, as in the first embodiment, frame number = 168 (time It is assumed that the communication quality with the first wireless terminal device 201 is deteriorated immediately before 740). Furthermore, it is assumed that the communication quality with the second wireless terminal apparatus 202 deteriorates immediately before the frame number = 168 (time 740).

FIG. 16 shows radio link recovery antenna setting information regarding the first radio terminal apparatus 201 in the third embodiment. Further, FIG. 20 shows radio link recovery antenna setting information related to the second radio terminal apparatus 202.

In the radio link recovery antenna setting information shown in FIG. 20, cell ID = 3, 4 does not correspond to any of the first to

third base stations

101, 102, 103. Cell ID = 0 indicates the first base station 101 as in the first and second embodiments. Accordingly, the radio link recovery antenna setting information shown in FIG. 19 requests assignment of the radio link recovery training signal only to the first base station 101 as the base station appearing in FIG.

In a wireless communication system, when communication quality deteriorates simultaneously in two wireless terminal devices, the base station needs to handle antenna setting information for wireless link recovery for two devices. In the third embodiment, a change is added to the second embodiment in that the base station is extended to handle a plurality of radio link recovery antenna setting information.

In Embodiment 3, the following changes (3A) and (3B) are performed on the base station of Embodiment 2. (3A) The storage area (that is, the storage unit 17) in the base station for holding the radio link recovery antenna setting information is expanded. (3B) In the radio link recovery process, the base station is changed so that it can handle a plurality of radio link recovery antenna setting information.

The above (3A) will be described. In Embodiment 3, the storage area inside the base station is expanded to have an area for holding N (N ≧ 2) radio link recovery antenna setting information. The plurality of radio link recovery antenna setting information held in the storage area inside the base station is referred to as a radio link recovery antenna setting information list.

An identification ID is assigned to each radio link recovery antenna setting information included in the radio link recovery antenna setting information list, and this ID is referred to as a radio link recovery antenna setting information ID. Further, the radio link recovery antenna setting information list [X] is defined to indicate the radio link recovery antenna setting information corresponding to the radio link recovery antenna setting information ID = X.

The above (3B) will be described. In the third embodiment, a plurality of pieces of radio link recovery antenna setting information are respectively obtained in steps S902, S906, S1201, S907, S909, S911, S912, and S913 of the flowchart shown in the second embodiment (FIG. 16). Change to handle. The contents of change in each step will be described below.

The step of determining whether or not the effective radio link recovery antenna setting information in step S902 of FIG. 16 is held will be described in two steps, a first half process and a second half process. In the first half of step S902, radio link recovery antenna setting information ID = X that satisfies the following conditional expression (7) is extracted from the radio link recovery antenna setting information list and listed.

Current frame number ≧ first frame number of radio link recovery antenna setting information list [X] (7)
What is extracted and listed is called an effective ID list. The valid ID list is held only in the processing flow of FIG. 16, and is discarded when the processing flow of FIG. 17 ends.

In the latter half of step S902, if there is one or more data in the valid ID list, it is determined that the valid radio link recovery antenna setting information is held, and the process proceeds to radio link recovery antenna setting derivation (step S906). ). On the other hand, if it is not determined that the effective radio link recovery antenna setting information is held, the process proceeds to the initial learning antenna setting process (step S903).

In the derivation of the radio link recovery antenna setting in step S906, for each radio link recovery antenna setting information ID included in the valid ID list, the corresponding radio link recovery antenna setting information is referred to, and the calculation of Expression (4) is performed. , List in parameter Recovery_Index and hold. For example, in the Recovery_Index [0], the calculation result of the equation (4) regarding the radio link recovery antenna setting information list [effective ID list [0]] is held. Also, in Recovery_Index [1], the calculation result of Expression (4) regarding the radio link recovery antenna setting information list [effective ID list [1]] is held.

The step of determining whether or not to allocate the radio link recovery training signal to the frequency corresponding to the FDM_Index of the current frame in step S1201 will be described in two steps, the first half process and the second half process.

In the first half process of step S1201, the Xth data satisfying the following conditional expression (8) is deleted from the valid ID list and the Recovery_Index list.

Recovery_Index [X] ≧ number of data in radio link recovery antenna setting information list [valid ID list [X]] (8)
In the latter half process of step S1201, if there is one or more data in the valid ID list, it is determined as a radio link recovery process, and the process proceeds to determination of whether the target cell is the own cell (step S907). On the other hand, if there is no data in the valid ID list, the process proceeds to the initial learning antenna determination process (step S903).

The step of determining whether or not the target cell in step S907 is the own cell will be described in two stages, the first half process and the second half process. In the first half of step S907, X that satisfies the following conditional expression (9) is listed.

Cell ID of antenna setting order list [Recovery_Index [X]] in antenna setting information list [valid ID list [X]] for radio link recovery = ID of own cell (9)
A list based on the conditional expression (9) is called a self cell ID list. In the latter half process of step S907, if there is one or more data in the own cell ID list, the process proceeds to a radio link recovery antenna determination process (step S913). On the other hand, if there is no data in the own cell ID list, the process proceeds to the initial learning antenna determination process (step S908).

In step S909, it is determined whether the antenna setting ID determined by the initial learning antenna determination process overlaps with the antenna setting ID of the own cell in the antenna setting order list.

In step S909, if there is a set of (X, Y) satisfying the following two conditional expressions (10) and (11) from the antenna setting order list for each data of the antenna setting information list for radio link recovery: It is determined that there is an overlap, and the training signal is stopped (step S910).

Cell ID of antenna setting order list [Y] in antenna setting information list [valid ID list [X]] for wireless link recovery = ID of own cell (10)
Base station antenna setting ID in antenna setting order list [Y] of antenna setting information list [valid ID list [X]] for wireless link recovery = antenna setting ID determined in initial learning antenna determination process (11)
If there is no combination of (X, Y) that satisfies the conditional expressions (10) and (11), it is determined that there is no overlap, and the process proceeds to step S911.

The step of determining whether or not to discard the radio link recovery antenna setting information in step S911 will be described in two steps, a first half process and a second half process. In the first half of step S911, when the following conditional expression (12) is satisfied for the radio link recovery antenna setting information list [valid ID list [X]], X is deleted from the valid ID list.

Repetition period × number of repetitions × FDM multiplexing number ≦ (result of calculation formula (1)) (12)
In the latter half process of step S911, if there is one or more data in the valid ID list, the process proceeds to the antenna setting information discarding process (step S912). On the other hand, if there is no data in the valid ID list, the process proceeds to step 904.

In the antenna setting information discarding process in step S912, the radio link recovery antenna setting information in the radio link recovery antenna setting information list [valid ID list [X]] is discarded from the radio link recovery antenna setting information list. Here, X is from 0 to the effective ID list length-1.

In the radio link recovery antenna determination process in step S913, the base station antenna setting ID of the antenna setting order list [Recovery_Index [0]] of the radio link recovery antenna setting information list [valid ID list [0]] is the antenna setting ID. Will be formally determined. The determined antenna setting ID is used for antenna setting of a training signal transmitted at any frequency of FDM # 0 to FDM # 3 corresponding to the FDM_Index of the current frame.

By the way, when reaching step S913, the valid ID list may include a plurality of data. In this case, it means that the allocation request of the radio link recovery training signal for a plurality of radio terminal apparatuses is completely overlapped in both time and frequency. In the above description of step S913, the 0th effective ID list is simply adopted. However, for example, a plurality may be selected in consideration of priority. The priority will be described in the fourth embodiment.

FIG. 21 is a diagram illustrating antenna setting IDs of training signals transmitted from the first to

third base stations

101, 102, and 103 in the radio link recovery processing according to the third embodiment. When FIG. 21 is compared with FIG. 18 of the second embodiment, in FIG. 21, the first base station 101 transmits the radio link recovery training signal to the second radio terminal device 202 in addition to the first radio terminal device 201. Is sending.

As shown in FIG. 21, the first base station 101 transmits a radio link recovery training signal at a frequency of FDM # 3 with an antenna setting ID = 105 at frame number = 169. Also, the first base station 101 transmits a radio link recovery training signal at the frequency of FDM # 0 with the antenna setting ID = 160 at the frame number = 170. Also, the first base station 101 transmits a radio link recovery training signal at an FDM # 1 frequency with an antenna setting ID = 170 at a frame number = 170.

Also, the first base station 101 transmits a radio link recovery training signal at an FDM # 3 frequency with an antenna setting ID = 105 at a frame number = 173. Also, the first base station 101 transmits a radio link recovery training signal at the frequency of FDM # 0 with the antenna setting ID = 160 at the frame number = 174. Also, the first base station 101 transmits a radio link recovery training signal at an FDM # 1 frequency with an antenna setting ID = 170 at a frame number = 174.

<Effect>
In the wireless communication system according to the third embodiment, there are a plurality of at least one wireless terminal apparatus, and a plurality of the wireless terminals among a plurality of base stations (that is, first to

third base stations

101, 102, 103). Deterioration detection unit 18 of the base station that is performing wireless communication with the device detects the interruption of wireless communication or the deterioration of communication quality with a plurality of wireless terminal devices (that is, the first and second wireless terminal devices 201 and 202). In this case, the radio link recovery antenna setting information generation unit 19 of the base station that has detected the disruption or degradation of the radio communication performs the radio link recovery antenna setting information based on the antenna setting pair candidate list for each of the plurality of radio terminal apparatuses. A list is generated, and the radio link recovery antenna setting information list is a list of radio link recovery antenna setting information for each of a plurality of radio terminal apparatuses. The base station that has detected the disruption or degradation of the wireless communication transmits a radio link recovery request to each of the base stations described in the antenna setting order list for each of the plurality of wireless terminal devices, and is transmitted. Each radio link recovery request includes the same radio link recovery antenna setting information list, and each transmitting / receiving unit 10 of the base station that transmitted the radio link recovery request and the base station that received the radio link recovery request. The radio link recovery training signal is transmitted at the timing at which the radio link recovery training signal is not simultaneously transmitted from a plurality of base stations at the same frequency based on the antenna setting order list and time information for each of the plurality of wireless terminal devices. Transmit a radio link recovery training signal to a plurality of the radio terminal devices A training signal transmitted by the antenna configuration described in the antenna setting order list for les.

In the third embodiment, radio link recovery processing is simultaneously performed for a plurality of radio terminal apparatuses. Therefore, even if communication quality deteriorates at the same time in a plurality of wireless terminal devices, the effect of quickly recovering the wireless link in each wireless terminal device can be expected.

<Embodiment 4>
In the third embodiment, radio link recovery processing is performed for a plurality of radio terminal apparatuses. In the fourth embodiment, each base station selects an antenna setting of a radio link recovery training signal to be transmitted based on priority when performing a radio link recovery process for a plurality of radio terminal apparatuses.

In the fourth embodiment, it is assumed that, in step S913 described in the third embodiment, the allocation requests for the radio link recovery training signals for a plurality of radio terminal apparatuses are completely overlapped in both time and frequency. If the assignments overlap, it is better to determine the priority and select the antenna setting pair candidate with a higher priority.

In the fourth embodiment, the following changes (4A), (4B), and (4C) are performed with respect to the third embodiment. (4A) An item of reception level is added to the antenna setting order list of the radio link recovery antenna setting information. (4B) A reception level setting process is added in the process of generating the radio link recovery antenna setting information (step S220 in FIG. 7). (4C) In radio link recovery antenna determination processing (step S913 in FIG. 17), an antenna setting ID having a good reception level is preferentially selected.

The above (4A) will be described. FIG. 22 is a diagram illustrating an example of radio link recovery antenna setting information regarding the first radio terminal apparatus 201. FIG. 23 is a diagram illustrating an example of radio link recovery antenna setting information regarding the second radio terminal apparatus 202. In each of FIG. 22 and FIG. 23, an item of reception level is added to the antenna setting order list of the radio link recovery antenna setting information.

The above (4B) will be described. In the fourth embodiment, when generating the radio link recovery antenna setting information in step S220 of FIG. 7, the radio link is referred to by referring to the reception level information included in the antenna setting pair candidate list of FIG. The reception level is set in the item of the reception level added to the antenna setting order list of the recovery antenna setting information.

The above (4C) will be described. In the fourth embodiment, in the radio link recovery antenna determination process in step S913 of FIG. 17, the antenna setting order list [Recovery_Index [X]] of the radio link recovery antenna setting information list [valid ID list [X]]. Select X with the maximum reception level. Then, the base station antenna setting ID of the antenna setting order list [Recovery_Index [X]] of the radio link recovery antenna setting information list [effective ID list [X]] is formally determined as the antenna setting ID. The formally determined antenna setting ID is used for antenna setting of a training signal transmitted at a frequency corresponding to the FDM_Index of the current frame.

FIG. 24 is a diagram illustrating antenna setting IDs of training signals transmitted from the first to

third base stations

101, 102, and 103 in the radio link recovery processing according to the fourth embodiment. FIG. 25 is a diagram illustrating an antenna setting ID of a training signal transmitted by each base station as a comparative example with FIG. 24 in the fourth embodiment. That is, FIG. 25 shows the first to third base stations when the radio link recovery antenna setting information shown in FIG. 22 and FIG. 23 except for the reception level is applied to the radio communication system in the third embodiment. It is a figure which shows antenna setting ID of the training signal which 101,102,103 transmits.

24 is compared with FIG. 25, in FIG. 24, the radio link recovery training signal transmitted at the frequency of FDM # 0 at frame number = 168 with respect to the radio link recovery training signal transmitted by the first base station 101. The antenna setting ID is changed from 100 to 160. In addition, the antenna setting ID of the radio link recovery training signal transmitted at the frequency of FDM # 0 in the frame number = 172 is changed from 100 to 160.

24. In FDM # 0 of frame number 168 and FDM # 0 of frame number = 172 in FIG. 24, the first and second

wireless terminal apparatuses

201 and 202 have overlapping wireless link recovery request assignments. Therefore, in the fourth embodiment, the reception level of the training signal is used as the priority, and the radio link recovery training signal is assigned to the antenna setting related to the second radio terminal apparatus 202 having a better reception level.

Also, in the FDM # 1 with the frame number 168 and the FDM # 1 with the frame number = 172 shown in FIG. Therefore, in the fourth embodiment, the reception level of the training signal is used as the priority, and the radio link recovery training signal is assigned to the antenna setting related to the first radio terminal apparatus 201 having a better reception level.

It is highly possible that the radio terminal apparatus can receive the antenna-trained training signal having a high reception level in the initial training in step S201 in FIG. 6 even during a radio link recovery attempt (step S208 in FIG. 7). Therefore, when the assignment of the radio link recovery training signal is duplicated in a plurality of radio terminal apparatuses as in the fourth embodiment, the reception level is used as a priority and assigned to the radio terminal apparatus having a better reception level. By using this method, the probability that the wireless terminal device can receive the training signal is increased. That is, it is possible to further reduce the time required for radio link recovery.

<Effect>
In the wireless communication system according to the fourth embodiment, the antenna setting order list includes the reception level related to each antenna setting, and the base station that has transmitted the wireless link recovery request and the base station that has received the wireless link recovery request. When the transmission frequency and the transmission time of the radio link recovery training signal overlap with each other for a plurality of wireless terminal devices (that is, the first and second wireless terminal devices 201 and 202), the transmission / reception unit 10 has a high reception level. Priority is given to the transmission of training signals for radio link recovery with antenna settings.

In this Embodiment 4, when the assignment of the radio link recovery training signal is duplicated in a plurality of radio terminal apparatuses, the reception level is used as a priority, and the method is assigned to a radio terminal apparatus having a better reception level. This increases the probability that the wireless terminal device can receive the training signal. That is, it is possible to further reduce the time required for radio link recovery.

It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted. Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

10, 20 transmission / reception unit, 11, 21 transmission antenna, 12, 22 reception antenna, 13, 23 transmission unit, 14, 24 reception unit, 15 inter-base station communication unit, 16, 25 control unit, 17 storage unit, 18 deterioration detection , 19 Radio link recovery antenna setting information generation unit, 26 Antenna setting pair candidate list generation unit, 27 Antenna setting pair determination unit, 50 Wired network, 101 First base station, 102 Second base station, 103 Third Base station, 112 shield, 201 first wireless terminal device, 202 second wireless terminal device, HW15 inter-base station communication circuit, HW16, HW25 processing circuit, HW17, HW26 memory, HW18 storage device.

Claims

It has multiple base stations that can communicate with each other,
Each of the plurality of base stations is capable of wireless communication with at least one wireless terminal device,
The at least one wireless terminal device can change the directivity of the transmission beam and the reception beam by changing antenna settings;
Each of the plurality of base stations is
A transmission / reception unit capable of changing the directivity of the transmission beam and the reception beam; and
A deterioration detecting unit for detecting communication interruption or communication quality deterioration in wireless communication with the wireless terminal device;
A radio link recovery antenna setting information generating unit for generating radio link recovery antenna setting information;
A storage unit for storing the radio link recovery antenna setting information;
A control unit that controls directivity of the transmission beam and the reception beam by changing antenna settings of the transmission / reception unit;
With
Among the plurality of base stations, when the deterioration detection unit of the base station that is performing wireless communication with the at least one wireless terminal device detects a break in wireless communication or a deterioration in communication quality,
The radio link recovery antenna setting information generation unit of the base station that detects the disruption or degradation of radio communication generates the radio link recovery antenna setting information based on an antenna setting pair candidate list,
The antenna setting pair candidate list is generated in initial training for starting wireless communication between the at least one wireless terminal device and any of the plurality of base stations,
The antenna setting pair candidate list is a list of combinations of antenna settings of the at least one wireless terminal device, identification information for identifying the base station, and antenna settings of the base station identified by the identification information. ,
The radio link recovery antenna setting information includes an antenna setting order list and time information serving as a reference for the time to start transmitting the radio link recovery training signal,
The antenna setting order list is a list that defines the order of combinations of identification information for identifying the base station and antenna settings of the base station identified by the identification information;
The base station that has detected the disruption or degradation of wireless communication transmits a radio link recovery request to each of the base stations described in the antenna setting order list,
Each of the transmitted radio link recovery requests includes the same radio link recovery antenna setting information,
The transmission / reception unit of each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request has a radio link recovery training signal based on the antenna setting order list and the time information. Transmit a radio link recovery training signal at a timing when is not simultaneously transmitted from multiple base stations at the same frequency,
The radio link recovery training signal is a training signal transmitted with the antenna setting described in the antenna setting order list.
Wireless communication system.
The time information is a first frame number indicating a time at which transmission of the radio link recovery training signal is started.
The wireless communication system according to claim 1.
When the radio link recovery antenna setting information generation unit generates the radio link recovery antenna setting information based on the antenna setting pair candidate list, wireless communication is interrupted or communication quality is reduced from the antenna setting pair candidate list. Exclude degraded antenna configuration pairs,
The radio | wireless communications system of Claim 1 or Claim 2.
The radio link recovery antenna setting information further includes a repetition period and a repetition count,
The base station that has detected the disruption or deterioration of wireless communication transmits a communication quality deterioration notification to the at least one wireless terminal device, and when the base station receives a response to the communication quality deterioration notification, a radio link The recovery antenna setting information generation unit sets the number of repetitions less, and when the base station does not receive a response to the communication quality deterioration notification, the radio link recovery antenna setting information generation unit sets the number of repetitions. Set more
The transmitting / receiving unit of each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request is configured to perform the radio link recovery for each antenna setting described in the antenna setting order list. Transmitting a training signal for the number of repetitions in the repetition period;
The radio | wireless communications system as described in any one of Claims 1-3.
A plurality of the at least one wireless terminal device;
Among the plurality of base stations, the deterioration detection unit of the base station that is performing wireless communication with a plurality of the wireless terminal devices detects a break in wireless communication or a deterioration in communication quality with the plurality of wireless terminal devices. if you did this,
The radio link recovery antenna setting information generation unit of the base station that detects the disruption or degradation of the radio communication, based on the antenna setting pair candidate list for each of the plurality of radio terminal apparatuses, Generate a list
The radio link recovery antenna setting information list is a list of the radio link recovery antenna setting information for each of a plurality of the wireless terminal devices,
The base station that detects the disruption or degradation of wireless communication transmits the wireless link recovery request to each of the base stations described in the antenna setting order list for each of a plurality of the wireless terminal devices,
Each of the transmitted radio link recovery requests includes the same radio link recovery antenna setting information list,
The transmission / reception unit of each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request includes the antenna setting order list and the time information for each of the plurality of radio terminal apparatuses. On the basis of transmitting the radio link recovery training signal at a timing at which the radio link recovery training signal is not simultaneously transmitted from a plurality of base stations at the same frequency,
The radio link recovery training signal is a training signal transmitted with an antenna setting described in the antenna setting order list for each of a plurality of the wireless terminal devices.
The radio | wireless communications system as described in any one of Claims 1-4.
The antenna setting order list includes a reception level related to each antenna setting,
The transmission / reception unit of each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request transmits the transmission frequency and transmission of the training signal for radio link recovery for the plurality of radio terminal apparatuses. If the times overlap, give priority to the transmission of the radio link recovery training signal of the antenna setting with a high reception level,
The wireless communication system according to claim 5.
Further comprising the at least one wireless terminal device;
The at least one wireless terminal device is:
A transmission / reception unit capable of changing the directivity of the transmission beam and the reception beam; and
In the initial training, an antenna setting pair candidate list generating unit for generating an antenna setting pair candidate list;
From the antenna setting pair candidate list, an antenna setting pair determination unit that determines an antenna setting pair used for communication with any of the plurality of base stations;
A control unit that controls directivity of the transmission beam and the reception beam by changing antenna settings of the transmission / reception unit;
With
When the at least one wireless terminal device receives a communication quality deterioration notification from a base station performing wireless communication among the plurality of base stations, or detects communication interruption or communication quality deterioration, the transmission / reception Change the directivity of the receiving beam of the part to omnidirectional,
The antenna setting pair candidate list generation unit updates the antenna setting pair candidate list based on the received training signal for radio link recovery,
The antenna setting pair determination unit determines an antenna setting pair to be used for communication with any of the plurality of base stations from the updated antenna setting pair candidate list.
The radio | wireless communications system as described in any one of Claims 1-6.
A control method for a wireless communication system, comprising:
The wireless communication system includes a plurality of base stations capable of communicating with each other,
Each of the plurality of base stations is capable of wireless communication with at least one wireless terminal device,
The at least one wireless terminal device can change the directivity of the transmission beam and the reception beam by changing antenna settings;
Each of the plurality of base stations can change the directivity of the transmission beam and the reception beam by changing the antenna setting,
The wireless communication system control method includes:
(A) the base station performing wireless communication with the at least one wireless terminal device among the plurality of base stations detecting a disconnection of wireless communication or a deterioration in communication quality;
(B) After the step (a), the base station that has detected a disruption or deterioration of radio communication generates radio link recovery antenna setting information based on an antenna setting pair candidate list; and
With
The antenna setting pair candidate list is generated in initial training for starting wireless communication between the at least one wireless terminal device and any of the plurality of base stations,
The antenna setting pair candidate list is a list of combinations of antenna settings of the at least one wireless terminal device, identification information for identifying the base station, and antenna settings of the base station identified by the identification information. ,
The radio link recovery antenna setting information includes an antenna setting order list and time information serving as a reference for the time to start the radio link recovery process,
The antenna setting order list is a list that defines the order of combinations of identification information for identifying the base station and antenna settings of the base station identified by the identification information;
The wireless communication system control method includes:
(C) After the step (b), the step in which the base station that has detected the disruption or deterioration of radio communication transmits a radio link recovery request to each of the base stations described in the antenna setting order list. In addition,
Each of the transmitted radio link recovery requests includes the same radio link recovery antenna setting information,
The wireless communication system control method includes:
(D) After the step (c), each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request is based on the antenna setting order list and the time information. A radio link recovery training signal is transmitted at a timing at which the radio link recovery training signal is not simultaneously transmitted from a plurality of base stations at the same frequency,
The radio link recovery training signal is a training signal transmitted with the antenna setting described in the antenna setting order list.
A control method for a wireless communication system.
The time information is a first frame number indicating a time at which transmission of the radio link recovery training signal is started.
The control method of the radio | wireless communications system of Claim 8.
In the step (b), when the antenna setting information for radio link recovery is generated based on the antenna setting pair candidate list, the antenna setting in which wireless communication is interrupted or communication quality is deteriorated from the antenna setting pair candidate list Pairs are excluded,
The control method of the radio | wireless communications system of Claim 8 or Claim 9.
The radio link recovery antenna setting information further includes a repetition period and a repetition count,
After the step (a), the base station that has detected the interruption or deterioration of wireless communication transmits a communication quality deterioration notification to the at least one wireless terminal device,
In the step (b), when the base station receives a response to the communication quality degradation notification, the number of repetitions is set less, and when the base station does not receive a response to the communication quality degradation notification, The number of repetitions is set more,
In the step (d), each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request is configured to transmit the radio link for each antenna setting described in the antenna setting order list. Transmitting a link recovery training signal for the number of repetitions in the repetition period;
The control method of the radio | wireless communications system as described in any one of Claims 8-10.
A plurality of the at least one wireless terminal device;
In the step (a), among the plurality of base stations, the base station that is performing wireless communication with the plurality of wireless terminal apparatuses is disrupted in wireless communication with the plurality of wireless terminal apparatuses or deteriorated in communication quality. Is detected,
In the step (b), the base station that has detected the disruption or degradation of radio communication generates a radio link recovery antenna setting information list based on the antenna setting pair candidate list for each of the plurality of radio terminal apparatuses. ,
The radio link recovery antenna setting information list is a list of the radio link recovery antenna setting information for each of a plurality of the wireless terminal devices,
In the step (c), the base station that has detected the disruption or deterioration of the radio communication transmits the radio link recovery to each of the base stations described in the antenna setting order list for each of the plurality of radio terminal apparatuses. Send a request,
Each of the transmitted radio link recovery requests includes the same radio link recovery antenna setting information list,
In the step (d), each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request includes the antenna setting order list for each of a plurality of the radio terminal devices, and Based on the time information, transmit the radio link recovery training signal at a timing at which the radio link recovery training signal is not simultaneously transmitted from a plurality of base stations at the same frequency,
The radio link recovery training signal is a training signal transmitted with an antenna setting described in the antenna setting order list for each of a plurality of the wireless terminal devices.
The control method of the radio | wireless communications system as described in any one of Claims 8-11.
The antenna setting order list includes a reception level related to each antenna setting,
In the step (d), each of the base station that has transmitted the radio link recovery request and the base station that has received the radio link recovery request transmits the radio link recovery training signal with respect to the plurality of radio terminal apparatuses. When the frequency and the transmission time overlap, give priority to the transmission of the radio link recovery training signal of the antenna setting with a high reception level,
The control method of the radio | wireless communications system of Claim 12.
The wireless communication system further comprises the at least one wireless terminal device,
The wireless communication system control method includes:
(E) When the at least one wireless terminal device receives a communication quality deterioration notification from a base station that performs wireless communication among the plurality of base stations, or detects communication interruption or communication quality deterioration Changing the directivity of the reception beam of the at least one wireless terminal device to omnidirectional;
(F) After the step (e), the at least one wireless terminal device updates the antenna setting pair candidate list based on the received training signal for radio link recovery;
(G) After the step (f), the at least one wireless terminal device determines an antenna setting pair to be used for communication with any of the plurality of base stations from the updated antenna setting pair candidate list. And a process of
Further comprising
The method for controlling a wireless communication system according to any one of claims 8 to 13.