JP5806202B2 - COMMUNICATION SYSTEM, STATION-side DEVICE, COMMUNICATION BAND CONTROL METHOD - Google Patents

Description

  The present invention relates to a communication system, a station-side device, and a communication band control method.

  In recent years, as a broadband access service using an optical fiber, a PON (Passive Optical Network) system in which one optical fiber is shared by a plurality of subscribers has been widely used. In the PON system, an OLT (Optical Line Terminal) is arranged as a station side device, and an ONU (Optical Network Unit) is arranged as a subscriber side device. In the downlink from the OLT to the ONU, data frames are continuously distributed as broadcast, and in the uplink from the ONU to the OLT, data frames transmitted from a plurality of ONUs are controlled in a time division manner so as not to collide. The In the PON system, a DBA (Dynamic Bandwidth Allocation) method is used to allocate an upstream communication band from the OLT to the ONU (see, for example, Patent Document 1).

JP 2012-151577 A

  However, in the case of the DBA method, the ONU transmits frames requesting communication band allocation to the OLT at regular time intervals according to the amount of data stored in the transmission buffer. Then, the OLT calculates a communication band to be allocated to the ONU in consideration of a communication band used by another ONU, and notifies the ONU. Then, the ONU transmits the data accumulated in the transmission buffer in the communication band assigned from the OLT to the OLT. For this reason, there is a problem that the delay time from when the ONU requests the OLT to allocate the communication band until the ONU actually transmits data to the OLT increases. For example, when the transmission data amount increases, there is a delay until the communication band is allocated according to the increase in the data amount. In communication services such as voice communication and video distribution, it is required that the delay time when transmitting and receiving data is as small as possible, and degradation of service quality due to data delay becomes a problem.

  An object of the present invention is to provide a communication system, a station-side device, and a communication band control method that can improve service quality by reducing data delay in a communication service.

A communication system according to one aspect is
In a communication system including a subscriber-side device and a station-side device connected to each other, and when a terminal is connected to a SIP server of a higher-level network via the subscriber-side device and the station-side device, the subscriber-side device is The data transmitted from the terminal is accumulated in the buffer, the data amount of the data accumulated in the buffer is notified to the station side device, the data held in the buffer is transmitted in the communication band instructed from the station side device, The station side device monitors the response message of the SIP server in response to the INVITE message transmitted from the terminal to the SIP server, and predicts the data amount of data to be transmitted next by the subscriber side device, and the predicted data amount and the subscriber side The communication bandwidth allocated to the subscriber side device is calculated according to the data amount notified from the device, and the calculated communication bandwidth is notified to the subscriber side device. .

One aspect by the station side device, a monitor means for monitoring a response message of the SIP server to the INVITE message transmitted to the destination SIP server the subscriber unit and the subscriber unit to which the terminal is connected, the response message Based on the prediction means for predicting the data amount of data to be transmitted next by the subscriber side device, and the communication band allocated to the subscriber side device according to the predicted data amount and the data amount notified from the subscriber side device And a notifying means for notifying the subscriber side apparatus of the calculated communication band.

A communication band control method according to one aspect is a communication band control method used in a communication system including a subscriber-side device and a station-side device connected to each other, wherein a terminal uses the subscriber-side device and the station-side device. The subscriber side device accumulates data transmitted from the terminal in a buffer and notifies the station side device of the amount of data stored in the buffer. Then, the data stored in the buffer is transmitted in the communication band instructed by the station side device, and the station side device monitors the response message of the SIP server in response to the INVITE message transmitted from the terminal to the SIP server. Then, the data amount of the data to be transmitted next by the subscriber side device is predicted, and the predicted data amount is notified from the subscriber side device. Depending on the data amount and the calculated communication bandwidth to be assigned to the subscriber units, and notifies the calculated communication band to the subscriber unit.

  The communication system, the station-side device, and the communication band control method disclosed herein can improve service quality by reducing delays in communication services that are required to have as little delay time as possible when transmitting and receiving data.

1 is a diagram illustrating an example of a PON system 100. FIG. It is a figure which shows an example of ONU102. It is a figure which shows an example of OLT101. It is a figure which shows an example of the OLT control part. It is a figure which shows an example of the control sequence of OLT101 and ONU102. It is a figure which shows the other example of the control sequence of OLT101 and ONU102. 3 is a diagram showing an example of connection between an IP phone 104 and a SIP server 108. FIG.

  Hereinafter, embodiments of a communication system, a station-side device, and a communication band control method disclosed in the present disclosure will be described in detail. FIG. 1 shows a PON system 100 as an example of a communication system according to the present embodiment. In FIG. 1, a PON system 100 has an OLT 101 as a station side device and a plurality of ONUs 102 as subscriber side devices. The OLT 101 and the plurality of ONUs 102 are connected via an optical coupler 103. In the example of FIG. 1, one OLT 101 accommodates five ONUs 102 from the ONU 102 (1) to the ONU 102 (5). The ONU 102 (3) and ONU 102 (4) are not shown.

  Here, when a specific ONU 102 is pointed out among the plurality of ONUs 102, (number) is added to the code and expressed as, for example, ONU 102 (1). Further, when the contents common to the ONU 102 (1) to the ONU 102 (5) are described, (number) is omitted and expressed as the ONU 102.

  In the PON system 100, on the downlink from the OLT 101 to the ONU 102, data frames are time-division multiplexed and continuously distributed like a broadcast. Further, in the uplink line from the ONU 102 to the OLT 101, the communication bands (transmission timings and transmission periods) of the plurality of ONUs 102 are controlled in a time division manner so that data frames transmitted from the plurality of ONUs 102 do not collide. The OLT 101 allocates an upstream communication band to each ONU 102 by the DBA method.

  In the example of FIG. 1, a telephone (IP (Internet Protocol) telephone) 104 is connected to the ONU 102 (1) as a user terminal. Further, a TV (TeleVision) 105 with a network function is connected to the ONU 102 (2), and a PC (Personal Computer) 106 is connected to the ONU 102 (5).

  In the following description, an example will be described in which the telephone 106 connected to the ONU 102 (1) makes a voice call via the SIP (Session Initiation Protocol) server 108. Note that the OLT 101 and the SIP server 108 are connected via a network 107.

  FIG. 2 is a diagram illustrating an example of the ONU 102. In FIG. 2, the ONU 102 includes a user IF (Interface) 201, an ONU control unit 202, a PONIF (Passive Optical Network Interface) 203, and a transmission buffer 204.

  A user IF 201 is an interface for connecting user terminals such as the telephone 104, the TV 105, and the PC 106 shown in FIG. 1, and for example, a LAN (Local Area Network) interface is used. Data input from the user terminal via the user IF 201 is temporarily stored in the transmission buffer 204.

  The ONU control unit 202 uses a CPU (Central Processing Unit) or the like, and controls the entire ONU 102. The ONU control unit 202 performs DBA control with the OLT 101. For example, the ONU control unit 202 notifies the OLT 101 of the amount of transmission data stored in the transmission buffer 204 and transmits the transmission data to the OLT 101 in the communication band allocated from the OLT 101. Further, the ONU control unit 202 extracts data addressed to itself from the data received by the PONIF 203 from the OLT side, and outputs the data to the user terminal side via the user IF 201.

  The PONIF 203 is an interface for communicating with the OLT 101 side. For example, the PONIF 203 converts the data read from the transmission buffer 204 by the ONU control unit 202 into an optical signal and transmits it to the OLT 101 side. Conversely, the PONIF 203 converts the optical signal received from the OLT 101 side into an electrical signal and converts it into an ONU control unit. To 202.

  For example, a semiconductor memory is used as the transmission buffer 204, and temporarily stores transmission data of the user terminal.

  As described above, the ONU 102 temporarily stores the transmission data of the user terminal in the transmission buffer 204, transmits the transmission data to the OLT 101 in the communication band assigned by the OLT 101, and receives the data addressed to the own apparatus received from the OLT 101. Output to.

  Next, the OLT 101 will be described. FIG. 3 is a diagram illustrating an example of the OLT 101. In FIG. 3, the OLT 101 basically includes a PONIF 301, an OLT control unit 302, and an upper network IF (InterFace) 303. Further, a packet filter unit 304 and an ONUDB (ONU DataBase) 305 for managing the ONU 102 are provided between the PONIF 301 and the upper network IF 303.

  The PONIF 301 is an interface for transmitting and receiving data to and from the ONU 102 side. For example, the PONIF 301 converts data transmitted / received to / from an upper network (network 107) via the packet filter unit 304 or control data transmitted / received by the OLT control unit 302 into an optical signal and communicates with the ONU 102 side.

  For example, a CPU or the like is used as the OLT control unit 302, and controls the entire OLT 101. In addition, the OLT control unit 302 performs DBA control with the ONU 102 and performs processing for assigning a communication band to the ONU 102 according to, for example, the amount of transmission data notified from the ONU 102. The processing of the OLT control unit 302 will be described in detail later.

  The host network IF 303 is an interface that is connected to the network 107 in FIG. 1 and accesses a host server. In the example of FIG. 1, the SIP server 108 is connected.

  The packet filter unit 304 discriminates the type of packet, filters control data for PON transmitted / received to / from the ONU 102, inputs / outputs it to / from the OLT control unit 302, filters user data, and enters the upper network IF 303. Output.

  The ONUDB 305 is a database for managing the MAC (Media Access Control) addresses and link states of a plurality of ONUs 102 accommodated by the OLT 101. The OLT control unit 302 authenticates the ONU 102 and manages the connection of the ONU 102 with the ONU DB 305. Then, the OLT control unit 302 transfers user data transmitted from the authenticated ONU 102 managed by the ONUDB 305 to the upper network 107.

  As described above, the OLT 101 manages the subordinate ONUs 102 and controls the ONUs 102 to communicate with the higher level network so that the ONUs 102 can transmit and receive to and from the higher level network. In this embodiment, as described with reference to FIG. 2, the ONU 102 temporarily accumulates data transmitted by the user terminal in the transmission buffer 204. And it transmits to OLT101 by the communication band allocated from OLT101, and outputs the data addressed to the own apparatus received from OLT101 to the user terminal.

  Next, processing contents of the OLT control unit 302 will be described. FIG. 4 is a diagram illustrating an example of processing contents of the OLT control unit 302. In FIG. 4, the OLT control unit 302 performs a filter control process 351, a monitor process 352, a band calculation process 353, a notification process 354, and a data amount prediction process 355.

  The filter control process 351 performs a process for controlling the operation of the packet filter unit 304 shown in FIG. For example, the filter control process 351 controls the packet filter unit 304 so as to transmit and receive PON control data to and from the ONU 102. Further, the filter control processing 351 controls the packet filter unit 304 so that communication data between the ONU 102 and the upper server is input / output to / from the upper network IF 303.

  The monitor process 352 performs a process of monitoring communication data between a server (for example, the SIP server 108 shown in FIG. 1) connected to the upper network 107 and the ONU 102. Then, the monitor process 352 determines whether or not the communication data to be monitored is a control message requesting the server to start a communication service from the ONU 102. When the communication data is a control message, the content of the communication service is notified to the data amount prediction process 355.

  The data amount prediction processing 353 performs processing for predicting the amount of data transmitted from the ONU 102 next based on the type of communication service indicated by the control message monitored by the monitor processing 352. For example, in the example of FIG. 1, the IP phone 104 of the ONU 102 (1) transmits a control message (voice communication service start request message) for making a call to the SIP server 108. The monitor process 352 notifies the data amount prediction process 353 that the voice communication service start request message has been monitored. Receiving this, the data amount prediction process 353 predicts a communication band necessary for the voice communication service, and outputs it to the band calculation process 354. In the OLT 101 shown in FIG. 3, a table indicating correspondence between various services and communication data amounts is stored in advance in the ONUDB 305 or the like, and the data amount prediction processing 353 refers to this table, and next Predict the communication bandwidth to be used.

  The bandwidth calculation processing 354 performs processing for calculating a communication bandwidth for the ONU 102 to transmit data next in accordance with the transmission data amount requested from the ONU 102. If the control message is not detected in the monitor process 352, the band calculation process 354 calculates a communication band based on the transmission data amount requested from the ONU 102 and outputs the communication band to the notification process 355. Further, when the monitor processing 352 detects a control message, the bandwidth calculation processing 354 is a communication bandwidth that combines the transmission data amount predicted by the data amount prediction processing 353 and the transmission data amount requested from the ONU 102 at this time. Is output to the notification process 355.

  The notification process 355 notifies the ONU 102 of the communication band calculated by the band calculation process 354. Here, the communication band is information including transmission start timing and transmission time of data time-division multiplexed by a plurality of ONUs 102.

  In this way, the OLT 101 according to the present embodiment monitors the control message between the ONU 102 and the upper server, and predicts the communication bandwidth according to the type of communication service, so that the data transmitted by the ONU 102 is transmitted. Delay can be reduced. In the above example, the communication with the SIP server 108 is monitored. However, the present invention can be similarly applied to a video distribution service such as a network television. As described above, the OLT 101 according to the present embodiment can improve the service quality by reducing the data delay in the communication service that is required to have the smallest possible delay time when transmitting and receiving data.

  Next, an example of a control sequence performed between the ONU 102 and the OLT 101 illustrated in FIG. 1 will be described with reference to FIG.

  (Step S401) The ONU 102 receives a control message j transmitted from a user terminal such as the IP phone 104, the TV 105, and the PC 106.

  (Step S <b> 402) The ONU 102 temporarily holds the control message j in the transmission buffer 204. Here, the data amount of the control message j is assumed to be (Dj).

  (Step S <b> 403) The OLT 101 transmits a Gate frame to the ONU 102. Here, the Gate frame is a communication confirmation message periodically transmitted by the OLT 101. The OLT 101 periodically transmits a Gate frame to the ONU 102, and in response to this, the ONU 102 requests a communication band for data to be transmitted next in the Report frame. Here, the Report frame is a communication confirmation response message returned from the ONU 102 to the OLT 101. The ONU 102 returns a Report frame to the OLT 101 even when there is no transmission data, and the OLT 101 manages the link state with the ONU 102.

  (Step S404) In order to transmit the control message j to the OLT 101 side, the ONU 102 notifies the OLT 101 side of the data amount (Dj) of the control message j with a Report frame. Accordingly, the ONU 102 requests the OLT 101 for a communication band for transmitting the control message j having the data amount (Dj).

  (Step S <b> 405) The OLT 101 notifies the ONU 102 of a Gate frame that notifies the ONU 102 of the communication band for transmitting the data amount (Dj) requested from the ONU 102 and permits transmission of the control message j.

  (Step S406) The ONU 102 reads the control message j temporarily held in the transmission buffer 204 and transmits it to the OLT 101 side.

  (Step S407) The control message j is transmitted from the ONU 102 to the OLT 101.

  (Step S408) The OLT 101 transmits a control message j received from the ONU 102 to the destination server via the network 107. In the example of FIG. 1, the OLT 101 transmits a control message j to the SIP server 108. In FIG. 5, the message from the server to the user terminal is omitted and not shown in the figure.

  (Step S409) The OLT 101 monitors the control message j and analyzes the contents. Then, the OLT 101 grasps that the communication service corresponding to the control message j is started.

  (Step S410) The OLT 101 periodically transmits a Gate frame to the ONU 102 as described above.

  (Step S <b> 411) The ONU 102 transmits a Report frame corresponding to a Gate frame periodically transmitted from the OLT 101 to the OLT 101. Here, an example is shown in which the ONU 102 requests the OLT 101 for a communication band for transmitting information on the data amount (Dm).

  Note that step S410 and step S411 do not have to be transmitted / received at the timing depicted in FIG. 5 (between step S409 and step S412), but here step S409 and step S411 are easy to understand. It is drawn between S412.

  (Step S412) Based on the type of communication service monitored in step S409, the OLT 101 predicts a communication band scheduled to be used in the communication service. Here, the OLT 101 predicts that the information on the data amount (Dα)) is transmitted in the communication service, and adds the data amount (Dα)) to the data amount (Dm)) notified from the ONU 102 in step S411. The amount (Dn)) is the amount of communication bandwidth allocated to the ONU 102.

  (Step S413) The OLT 101 transmits to the ONU 102 a Gate frame that permits a communication band for transmitting the data amount (Dn).

  The processes so far (from step S401 to step S413) are processes related to the control message j transmitted from the user terminal. The OLT 101 monitors the control message j, recognizes the start of the communication service, and performs a process of assigning a communication band corresponding to the type of the communication service to the ONU 102.

  On the other hand, the user terminal starts a communication service. In FIG. 5, a message for notifying communication service permission from the upper server to the user terminal is omitted, but the ONU 102 starts the communication service upon receiving the communication service permission.

  (Step S414) The user terminal transmits traffic p (data amount (Dp))) corresponding to the communication service to the upper server.

  (Step S415) The ONU 102 temporarily stores the data of the traffic p transmitted by the user terminal in the transmission buffer 204.

  (Step S416) Since the communication band allocation described in Step S413 is performed, the ONU 102 can use a communication band (data amount (Dn)) equal to or higher than the traffic p. Therefore, the ONU 102 transmits the traffic p having the data amount (Dp) accumulated in the transmission buffer 204 to the OLT 101. Note that data amount (Dn))> data amount (Dp)).

  (Step S417) The ONU 102 transmits the data of the traffic p to the OLT 101.

  (Step S418) The OLT 101 transmits the data of the traffic p received from the ONU 102 to the upper server.

  In this way, the ONU 102 is provided with a sufficient communication band for transmitting the traffic p data from the OLT 101 before inputting the traffic p data from the user terminal, so that the delay time t is shortened. Can do. Here, the delay time t is a time from when the ONU 102 receives the traffic p data from the user terminal to when the traffic p data is transmitted to the OLT 101.

  Here, an example in which the OLT 101 does not predict the communication band will be described with reference to FIG. 6 so that the features of the PON system 100 according to the present embodiment can be easily understood. FIG. 6 is a diagram corresponding to FIG. 5 and the same reference numerals as those in FIG. 5 perform the same processes. However, when the OLT 101 transmits the control message j received by the ONU 102 to the upper server, the OLT 101 performs the process of step S409 in FIG. 5 (a process of monitoring the contents of the control message j to determine the start of the communication service). Not performed. Further, the OLT 101 does not perform the process of step S412 in FIG. 5 (a process of predicting a communication band according to a communication service). For this reason, in the example of FIG. 6, the ONU 102 has the traffic p of the data volume (Dp)) larger than the data volume (Dm)) because the communication band allocated in the Gate frame in step S413a is the data volume (Dm)). Is difficult to send. Therefore, the ONU 102 transmits a report frame to the OLT 101 and requests a communication band in which the data amount (Dp)) can be transmitted (step S451). Receiving this, the OLT 101 permits a communication band in which the data amount (Dp)) can be transmitted (step S452). The ONU 102 that is allowed a communication band capable of transmitting the data amount (Dp) from the OLT 101 transmits the traffic p data stored in the transmission buffer 204 to the OLT 101 (step S416).

  In this manner, the ONU 102 requests the OLT 101 for a communication band for transmitting the data amount (Dp) of the traffic p after receiving the traffic p data from the user terminal. Then, the ONU 102 transmits the data of the traffic p accumulated in the transmission buffer 204 to the OLT 101 after waiting for the communication band for transmitting the data amount (Dp) from the OLT 101 to be permitted. Therefore, the delay time T from the reception of the traffic p data from the user terminal to the transmission of the traffic p data to the OLT 101 is longer than the delay time t in FIG. When this delay time is long, there arises a problem that the quality of a communication service that needs to be communicated with a delay time as short as possible, such as voice communication of the IP phone 104 and streaming video of the TV 105, is caused. For example, when voice communication is performed with the IP phone 104, it takes time to communicate between the caller and the callee, and smooth conversation is difficult. With satellite telephones and the like, it is said that smooth conversation becomes difficult when the delay time exceeds 300 msec.

  Next, an example in which IP phone 104 communicates with SIP server 108 will be described with reference to FIG. FIG. 7 is a diagram corresponding to FIG. 5, and the same reference numerals as those in FIG. 5 perform the same processes. The difference from FIG. 5 is that the control messages in steps 401, 407, and 408 are INVITE messages in steps S401a, 407a, and 408a, respectively. The INVITE message is a control message for making a call with the IP phone 104. Upon receiving the INVITE message, the SIP server 108 returns a response frame permitting the telephone call (step S461). The response frame is transmitted from the SIP server 108 to the OLT 101, and transferred from the OLT 101 to the ONU 102 to which the IP telephone 104 is connected (step S462). The ONU 102 transfers the response frame received from the OLT 101 to the IP phone 104 (step S463).

  On the other hand, the OLT 101 that has monitored the INVITE message recognizes the start of the telephone service, and calculates a communication band corresponding to the amount of voice data (step S412). Then, the OLT 101 notifies the ONU 102 of the obtained communication band (step S413). The OLT 101 may monitor not a control message from the user terminal to the server but a response message from the server to the user terminal. Alternatively, the OLT 101 may monitor both messages and determine the start of the communication service.

  The IP phone 104 that is permitted to make a telephone call in step S463 transmits voice data (step S414a). The audio data is temporarily stored in the transmission buffer 204 (step S415). At this time, since the OLT 101 has allocated a communication band sufficient for transmitting audio data in step S413, the OLT 101 transmits the audio data stored in the transmission buffer 204 to the OLT 101 (steps S416 and 417a). Then, the audio data is transmitted from the OLT 101 to the SIP server 108 (step S418a).

  In this way, the OLT 101 monitors the INVITE message for requesting the SIP server 108 to start the IP telephone service from the SIP server 108, and confirms that a large volume of voice data is transmitted from the ONU 102 accommodating the IP telephone 104. Predict. The OLT 101 can allocate a bandwidth sufficient for voice data transmission to the ONU 102 before a request for a communication bandwidth necessary for voice data transmission is received from the ONU 102. As a result, the ONU 102 can immediately transmit voice data input from the IP phone 104 to the OLT 101.

  In the above example, the case of the IP telephone 104 has been described. However, the present invention can be similarly applied to a communication service that requires low delay, such as a video streaming service. Even when the communication service ends, the OLT 101 can predict the end of the communication service by monitoring a control message between the user terminal and the server. As a result, the OLT 101 can allocate a communication band with a reduced communication service band to another ONU 102 before a request for a communication band after the communication service ends from the ONU 102, thereby eliminating unnecessary bandwidth allocation. be able to. As described above, the PON system 100 according to the present embodiment can improve the service quality by reducing the delay in a communication service that requires a low delay.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

DESCRIPTION OF SYMBOLS 100 ... PON system; 101 ... OLT; 102 ... ONU; 103 ... Optical coupler; 104 ... IP telephone; 105 ... TV; 106 ... PC; 107 ... Network 108 ... SIP server; 201 ... user IF; 202 ... ONU control unit; 203 ... PONIF; 204 ... transmission buffer; 301 ... PONIF; 302 ... OLT control unit 303 ... Upper network IF; 304 ... Packet filter unit; 305 ... ONUDB; 351 ... Filter control processing; 352 ... Monitor processing; 353 ... Band calculation processing; Notification processing; 355 ... Data amount prediction processing

Claims (5)

A communication system including a subscriber side device and a station side device connected to each other,
When the terminal is connected to the SIP server of the higher level network via the subscriber side device and the station side device,
The subscriber side device accumulates data transmitted from the terminal in a buffer, notifies the station side device of the amount of data stored in the buffer, and uses a communication band instructed by the station side device. Send the data held in the buffer,
The station side device monitors a response message of the SIP server in response to an INVITE message transmitted from the terminal to the SIP server, predicts the data amount of data to be transmitted next by the subscriber side device, and predicts the data Calculating a communication band to be allocated to the subscriber side apparatus according to the amount and a data amount notified from the subscriber side apparatus, and notifying the subscriber side apparatus of the calculated communication band. Communications system. The communication system according to claim 1,
The communication system is a PON system;
The subscriber-side device and the station-side device correspond to the ONU and OLT of the PON system, respectively. Monitoring means for monitoring a response message of the SIP server in response to an INVITE message to be transmitted to a SIP server that is a communication destination of the subscriber side device and a subscriber side device to which a terminal is connected;
Predicting means for predicting a data amount of data to be transmitted next by the subscriber side device based on the response message ;
Calculating means for calculating a communication band to be allocated to the subscriber side device according to the predicted data amount and the data amount notified from the subscriber side device;
A station-side device comprising: notification means for notifying the subscriber-side device of the calculated communication band. In the station side apparatus of Claim 3 ,
The subscriber-side device and the station-side device correspond to an ONU and an OLT of a PON system, respectively. A communication band control method used in a communication system including a subscriber side device and a station side device connected to each other,
When the terminal is connected to the SIP server of the higher level network via the subscriber side device and the station side device,
The subscriber side device accumulates data transmitted from the terminal in a buffer, notifies the station side device of the amount of data stored in the buffer, and uses a communication band instructed by the station side device. Send the data held in the buffer,
The station side device monitors a response message of the SIP server in response to an INVITE message transmitted from the terminal to the SIP server, predicts the data amount of data to be transmitted next by the subscriber side device, and predicts the data Calculating a communication band to be allocated to the subscriber side apparatus according to the amount and a data amount notified from the subscriber side apparatus, and notifying the subscriber side apparatus of the calculated communication band. Communication bandwidth control method.

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