WO2008145073A1

WO2008145073A1 - A method, apparatus and tdd system for regulating the transmission power

Info

Publication number: WO2008145073A1
Application number: PCT/CN2008/071150
Authority: WO
Inventors: Wei Ruan; Yinggang Du
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-05-31
Filing date: 2008-05-30
Publication date: 2008-12-04
Also published as: CN101316125A

Abstract

This invention discloses a method for regulating the transmission power which includes the following steps: receiving downlink pilot signal and acquiring the channel gain value of each time-frequency block signal; according to said channel gain value, regulating the primary transmission power of each time-frequency block signal and acquiring the actual transmission power of each time-frequency block signal. This invention also discloses an apparatus for regulating the transmission power which includes a channel gain acquiring module and a transmission power regulating module. Furthermore, this invention discloses a TDD system which includes at least one said apparatus for regulating the transmission power. The embodiments of this invention acquires the channel gain value according to downlink pilot signal by using the symmetry of the uplink and downlink of TDD system, and regulates the primary transmission power of each sub-carrier signal so as to reduce the damage to the orthogonality of uplink control channel from the time-varying channel and improve the performance of non-coherent detection in uplink channel.

Description

Transmitting power adjustment method, device timely division duplex system

Technical field

The invention relates to the field of carrier communication, in particular to a transmission power control method and a device for time division duplex (TDD) system. Background technique

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier transmission technology that divides the spectrum into many sub-carriers. Each sub-carrier is modulated at a lower rate, because this technology has good performance. It is resistant to multipath delay and is therefore widely used in cellular mobile systems. Multiple access to OFDM, or 0FDMA, can be achieved by allocating different subcarriers to different users. Each narrowband subcarrier uses different modulation schemes, such as 16QAM, 64QAM, etc., and then uses Inverse Fast Fourier Transforms (IFFT) to provide OFDM modulation. The data to be transmitted is mapped to the symbol of OFDM, and after IFFT, the cyclic prefix is added and sent out. The receiving end uses the Fast Fourier Transforms (FFT) to solve the OFDM symbols, and extracts the data mapped to the symbol.

In the 0FDMA system, different users are assigned different resources (time, space, frequency resources) to realize sharing of resources by different users, and the system must indicate on which resources each terminal will transmit data. As the number of users increases, the overhead for transmitting resource assignment information will increase. For the reverse control channel, the signaling transmitted by each channel is short, and the number of resources that can be allocated by the system is limited. At the same time, data between different channels of different users cannot be encoded to improve transmission performance.

The Wa 1 sh code is an orthogonal spreading code and is commonly used as a spreading code in a spread spectrum system. The Wa 1 sh code can eliminate or suppress multiple access interference (Multiple Access Interferences). At the same time, the Walsh code can also be used for the transmission of information sequences. For example, a 10-bit information series can be mapped to a Walsh code of length 1024, and a 1024 Walsh code is used at the receiving end to correlate with the received information series, due to the Walsh code. Orthogonality, the series of information can be recovered by detecting the largest correlation peak, which is non-coherent detection. Mapping of information sequences belonging to different channels of different users into After the Wa l sh code, different scrambling codes are added to implement multiplexing of the same physical resources by different channels of different users. At this time, the channels sent by different users on different channels can be regarded as interference processing. Under the condition of ensuring the performance of the control channel, it is not necessary to transmit information on a fixed resource (or a variable resource, but the terminal can know its location according to its changing law). Resource assignment information reduces the overhead of control information.

In the UMB1.0 standard, in order to improve the communication quality of the system, a similar spread spectrum scheme is proposed in the reverse control channel of the OFDM system. In the OFDM system, the characteristics of the Wahl code are used to transmit the control information. In addition to the access sequence, the frame length transmitted in each control channel is generally less than or equal to 10 bits (corresponding to 1024 sequences). In order to make full use of the resources of the WaSh code while minimizing interference, divide the 1024 sequences into several subsets, except Outside the access channel, each control channel occupies a subset. Row or column), get a 1024-bit Wahl code, and then scramble the Wahl code. The access channel is also treated similarly. The WALSH codes scrambled by different uplink control channels are added and combined, and the combined 1024 bits are interleaved and scrambled by another scrambling code to distinguish different cell or sector. The output 1024 bits are divided into 8 sub-blocks, each block contains 128 bits, and 128-point FFT (FAST FOURIER TRANSFORMATION) is output for each block. 128 complex values are obtained, and the resulting 1024 complex values are carried in the 0FDM system. Continuous 128 subcarriers and 8 symbols. Thus, a reverse control block occupies a bandwidth of 1.25 MHz and the length of one physical frame. This system superimposes different user data of different channels on the same physical resource, and does not need resource assignment information when the system performance is satisfied.

In this scheme, the receiving algorithm is non-coherent reception. In the frequency division duplex mode (FDD), since there is no channel information of the uplink channel, there is an implicit assumption in the terminal transmission, that is, the control of the entire reverse control channel. The channel of the block is a coherent channel. In other words, the channel gain of each time-frequency block on the control block channel is the same. Therefore, the transmit power on each time-frequency block is exactly the same at the time of transmission.

However, in fact, at the receiving end, the channel gain of the entire control segment is not a uniform value, and there is always a difference between each time-frequency block, especially in fast fading channels, so this assumption is relatively rough. of. Therefore, when transmitting control information and transmitting according to this assumption, orthogonality between different Wa s codes cannot be guaranteed. In the synchronous system, the orthogonality of the Wahl code can be fully guaranteed only when the channels are completely consistent. If the channel changes, the orthogonality is destroyed, which increases the probability of error. A waste of information. Summary of the invention

The purpose of the embodiments of the present invention is to provide a method for adjusting the transmit power and a device for timely splitting and duplexing according to the defect that the performance of the non-coherent detection is poor when transmitting the control information in the FDD mode, and the uplink and downlink channels can be according to the TDD mode. Symmetrical characteristics adjust the uplink transmit power to achieve good non-coherent detection performance.

To achieve the above objective, an embodiment of the present invention provides a method for adjusting a transmission power, including the following steps:

Receiving a downlink pilot signal, and obtaining a channel gain value of each time-frequency block signal;

And adjusting an original transmit power of each of the time-frequency block signals according to the channel gain value to obtain an actual transmit power of the respective time-frequency block signals.

In order to achieve the above object, an embodiment of the present invention further provides a transmit power adjustment apparatus, including:

a channel gain obtaining module, configured to obtain a channel gain value of each time-frequency block signal according to the downlink pilot signal;

And a transmit power adjustment module, configured to be connected to the channel gain obtaining module, configured to adjust an original transmit power of each time-frequency block signal according to the channel gain value, to obtain an actual transmit power of each time-frequency block signal.

An embodiment of the present invention further provides a time division duplex system, including at least one transmit power adjustment device, where the transmit power adjustment device is configured to obtain a channel gain value of each time-frequency block signal according to the downlink pilot signal, according to the The channel gain value adjusts the original transmit power of the respective time-frequency block signals to obtain the actual transmit power of the respective time-frequency block signals. Based on the foregoing technical solution, the embodiment of the present invention utilizes the symmetry of the uplink and downlink channels of the TDD device, obtains the channel gain value according to the downlink pilot signal, and adjusts the original transmit power of each time-frequency block signal, thereby reducing the time-varying channel pair. The destruction of the orthogonality of the uplink control channel improves the non-coherent detection performance of the uplink channel. DRAWINGS

1 is a schematic flow chart of a first embodiment of a method for adjusting transmit power according to the present invention;

2 is a schematic flow chart of a second embodiment of a method for adjusting transmit power according to the present invention;

3 is a schematic flow chart of a third embodiment of a method for adjusting a transmit power according to the present invention;

4 is a schematic structural view of a first embodiment of a transmission power adjusting device according to the present invention;

FIG. 5 is a schematic structural diagram of a second embodiment of a transmission power adjusting apparatus according to the present invention; FIG.

6 is a schematic structural diagram of a third embodiment of a transmission power adjusting device according to the present invention;

FIG. 7 is a schematic structural view of a fourth embodiment of a transmission power adjusting apparatus according to the present invention. detailed description

In the embodiment of the present invention, the channel gain is obtained by using the symmetry of the uplink and downlink channels in the TDD mode before the signal is transmitted, and then the transmit power is adjusted, thereby improving the non-coherent detection performance of the uplink channel.

FIG. 1 is a schematic flowchart diagram of a first embodiment of a method for adjusting a transmission power according to the present invention. This embodiment includes the following steps:

Step 1 01: Obtain, according to the downlink pilot signal received by the terminal, a channel gain value of each time-frequency block signal, where a channel gain value of the time-frequency block signal is a channel gain value of the sub-carrier;

Step 1 02: Adjust an original transmit power of each time-frequency block signal according to the channel gain value before performing uplink transmission, to obtain an actual transmit power of each of the sub-carrier signals.

This embodiment is applicable to a mobile communication system adopting a TDD mode, in which different time slots on the same frequency channel (ie, carrier) are received and transmitted to ensure time to separate the receiving and transmitting channels, thereby making full use of the wireless spectrum. . Since the same frequency channel is used, it can be used for downlink reception. To estimate the channel gain. The original transmit power is adjusted by using the channel gain, and the adjusted actual transmit power is obtained, and then the signal is transmitted, thereby improving the transmission performance of the uplink control channel.

There are many ways to obtain the channel gain value. For example, since the pilot signal Pilot is known, the received signal Received can be divided by the pilot signal to obtain the channel gain of the pilot signal position, that is, H=Received/Pilot. Then, the channel gain of each time-frequency signal block is obtained by interpolation (including linear interpolation or nonlinear interpolation) in the adjacent time domain or frequency domain.

Here, the channel gain is used, i is the number of the subcarrier of the resource block occupied by the transmitted signal, and j is the number of the symbol of the resource block occupied by the transmitted signal, i=l, 2, ..., 8; j=l, 2 , ..., 128, the channel gain of the embodiment includes amplitude and phase, and the original transmit power of each time-frequency block signal is represented by Sij, where the signal of Sij is used as the interleaved scrambled signal, which may be randomized The signal in the channel, or the control channel such as the reverse ACK channel, the CQI channel in the C-A control block, the BFCH channel, the VCQI channel, the MCQI channel, and the SFCH channel, may also be any other channel using non-coherent detection.

When power adjustment is performed, the original transmit power of each time-frequency block signal can be divided by the channel gain to obtain the actual transmit power of each new time-frequency block signal, that is, the following formula:

T^S H^ i=l, 2, 8; j=l, 2, ..., 128

If the adjusted signal power on a time-frequency block exceeds the maximum range of the power amplifier or a certain threshold, the maximum value or threshold may be directly taken as follows:

Here sign ( ) is a symbolic function. The range of values of the subscripts i and j varies according to the channel. For example, each 2*8 reverse ACK control block in the reverse ACK channel is selected after the DFT sequence is selected and scrambled, but is adjusted by the above method. The values of the subscripts i and j are different from the above examples, where i = 1 or 2, j = 1, 2, 8.

In this embodiment, the amplitude of Sij is constant, and the phase change is also small, and the phase and amplitude of H vary greatly. Therefore, in order to binize the type of the transmitted signal, quantization can also be performed, for example, the phase is quantized into 4 Levels, 1/4, 3 1/4, 5 1/4, and 7 1/4, respectively, quantify the amplitude as Dry grades, and so on. This approach can also partially mitigate the effects of degeneration on the downlink to uplink channel.

In this embodiment, the adjustment process is to directly divide the transmission power by the channel gain value. Although this method is theoretically clear, in practical applications, due to the time variation of the channel gain value, the hardware configuration requirements are relatively high. Therefore, in order to reduce the hardware requirements, the channel gain value can be quantized, for example, the phase is quantized into four levels, namely ^, ^, and ^, respectively.

4 4 4 4

The quantization is a number of levels, and the division of the channel gain values of the predetermined phases can be achieved by the existing phase retarder. This quantization method takes into account both the time-varying channel gain value and the hardware implementation cost.

Before dividing the channel gain, the method further includes quantizing the channel gain to a preset phase and

/ or the step of the magnitude of the value.

As shown in FIG. 2, it is a schematic flowchart of the second embodiment of the method for adjusting the transmit power of the present invention. It can be seen from the previous embodiment that the adjusted total transmit power may exceed the transmit power before the adjustment. In order to maintain the consistency of the power before and after, and does not affect the overall power control, it is also possible to perform normalization adjustment based on the total transmit power before and after the adjustment.

Different from the previous embodiment, after obtaining the actual transmit power of each time-frequency block signal, the embodiment further includes step 103, that is, calculating the total transmit power and the actual transmit power of each time-frequency block signal respectively. The original transmit power and the total actual transmit power, and determine whether the total actual transmit power is greater than the total original transmit power, if yes, perform step 104; otherwise, use the obtained actual transmit power for signal transmission; Step 1 04 for the actual time-frequency block The transmit power performs a normalization operation.

The total original transmit power is expressed by ∑|τ .| ² , and the total actual transmit power is expressed by ∑| | ² , if the total transmit power becomes smaller, no normalization is required, but if the total transmit power becomes larger, each need to be The actual transmit power of the time-frequency block is uniformly multiplied by the adjustment factor = ∑ | | ² /∑^| ² , since the total actual transmit power is large, δ < 1. With this normalization operation, the number of executions can be limited to achieve a balance of performance and complexity. The normalization condition may be further limited, that is, if the ratio of the total actual transmit power to the total original transmit power is less than a preset threshold, the actual transmit power may be directly used for signal transmission, otherwise the normalization operation is performed. For example, if the total actual transmit power is increased by 5% or less relative to the total original transmit power, normalization is not required, and when it exceeds 5%, normalization is performed to ensure the consistency of the total transmit power before and after the adjustment.

Generally, the channel transmitted at this time is somewhat different from the channel when the downlink channel is previously estimated. If the terminal finds that the channel changes rapidly when performing channel estimation, for example, the time variation of the channel is very strong when the terminal is moving at a high speed. If the channel coherence condition is not satisfied in the frame, then pre-equalization has lost its meaning. Therefore, it is necessary to judge the channel coherence conditions. As shown in FIG. 3, it is a schematic flowchart of a third embodiment of a method for adjusting a transmit power according to the present invention. Compared with the first embodiment, the present embodiment increases the original transmit power of each time-frequency block signal before adjusting. In step 100, step 100 determines whether the channel transmitted by the signal satisfies the coherent condition. If the coherent condition is met, the adjustment operation in the first embodiment is performed. If not, the direct transmission may be performed in the existing manner.

For how to determine whether the channel transmitted by the signal satisfies the coherent condition, it can be selected according to the terminal capability. If the terminal supports the speed measurement function, it can determine whether the speed of the terminal exceeds the speed threshold, and if it exceeds, it determines that the coherent condition is not satisfied. If the terminal does not support the speed measurement, it may be determined whether the amplitude of the channel gain value of each time-frequency block signal exceeds the amplitude threshold, that is, when the multiple difference between the maximum value and the minimum value of the channel gain is greater than the amplitude threshold, it is determined that the correlation is not satisfied. And determining whether the number of consecutive changes in the sign of the real or imaginary part of the channel gain value of each time-frequency block signal exceeds the number of times threshold, and if so, determining that the coherent condition is not satisfied.

Step 100 in this embodiment can also be applied to the second embodiment described above.

As shown in FIG. 4, it is a schematic structural diagram of a first embodiment of a transmit power adjustment apparatus according to the present invention, including a channel gain obtaining module 1 and a transmit power adjustment module 2, and the channel gain obtaining module 1 can obtain each time frequency according to a downlink pilot signal. Block channel gain value; transmit power adjustment module 2 and letter The channel gain obtaining module 1 is connected to adjust the original transmit power of the respective time-frequency block signals according to the channel gain value to obtain actual transmit power of the respective time-frequency block signals.

As shown in FIG. 5, it is a schematic structural diagram of a second embodiment of a transmit power adjustment apparatus according to the present invention. The transmit power adjustment module 2 further includes a calculation module 21 and a transmit power determination module 22, wherein the calculation module 21 is connected to the channel gain obtaining module 1. The original transmit power of each time-frequency block signal can be divided by the channel gain to obtain the actual transmit power of each new time-frequency block signal. The transmit power determining module 22 is configured to determine whether the actual transmit power of each time-frequency block signal meets a preset range. If the actual transmit power of the time-frequency block signal is not within the preset range, set a predetermined transmit power value as the time-frequency block signal. Actual transmit power.

As shown in FIG. 6 , it is a schematic structural diagram of a third embodiment of a transmit power adjustment apparatus according to the present invention. Compared with the previous embodiment, the transmit power adjustment module in this embodiment further includes: a total original power calculation module 23, The actual transmit power module 24 and the normalization module 25. The total original power calculation module 23 is connected to the calculation module 21 for calculating the total original transmission power according to the original transmission power of each time-frequency block signal. The total actual transmit power module 24 is coupled to the calculation module 21 for calculating the total actual transmit power based on the actual transmit power of each time-frequency block signal. The normalization module 25 is connected to the total original power calculation module 23 and the total actual transmit power module 24, and after obtaining the actual transmit power of each time-frequency block signal, if the total actual transmit power is greater than the total original transmit power, the time will be The actual transmit power of the frequency block is normalized.

FIG. 7 is a schematic structural diagram of a fourth embodiment of a transmit power adjustment apparatus according to the present invention. Compared with the first embodiment, the embodiment further includes a coherent condition determination module 3, a channel gain obtaining module 1 and a transmission. The power adjustment module 2 is connected to determine whether the channel for signal transmission satisfies the coherent condition, and then performs an adjustment operation; otherwise, the original transmission power is directly used for signal transmission.

The transmission power adjustment system embodiment of the present invention includes at least one transmission power adjustment device, and the transmission power adjustment device is configured to obtain channel gain values of respective time-frequency block signals according to the downlink pilot signals, and the respective The original transmit power of the time-frequency block signal is adjusted to obtain the actual transmit power of the respective time-frequency block signals. The transmit power adjustment module may include a channel gain obtaining module and a transmit power adjustment module, where the channel gain obtaining module is configured to obtain a channel gain value of each time-frequency block signal according to the downlink pilot signal; and a transmit power adjustment module is configured to use the channel gain The value adjusts the original transmit power of each time-frequency block signal to obtain the actual transmit power of the respective time-frequency block signals, which is connected to the channel gain obtaining module. The respective transmit power adjustment means given in the above embodiment of the apparatus can also be used in the embodiment of the present system.

Through the foregoing method for adjusting the transmit power and the embodiment of the device to divide the duplex system in time, the present invention utilizes the symmetry of the uplink and downlink channels of the TDD device, obtains the channel gain value according to the downlink pilot signal, and obtains the original transmit power of each subcarrier signal. The adjustment is performed to reduce the disruption of the orthogonality of the uplink control channel by the time-varying channel, and the non-coherent detection performance of the uplink channel is improved.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not to be construed as limiting thereof; although the present invention will be described in detail with reference to the preferred embodiments, those skilled in the art should understand that The invention is not limited to the spirit of the technical solutions of the present invention, and should be included in the scope of the technical solutions claimed in the present invention.

Claims

Claim

A method for adjusting a transmission power, comprising:

The transmission power adjustment method according to claim 1, wherein the adjusting the original transmission power of each time-frequency block signal according to a channel gain value comprises: using the respective time-frequency block signals The original transmit power is divided by the channel gain to obtain the actual transmit power of the new respective time-frequency block signals.

The method for adjusting a transmit power according to claim 2, wherein after obtaining the actual transmit power, determining whether the actual transmit power meets a preset range for the respective time-frequency block signals, if the actual time-frequency block signal is If the transmit power is not within the preset range, the predetermined transmit power value is used as the actual transmit power of the time-frequency block signal.

The transmission power adjustment method according to claim 2 or 3, characterized in that before dividing by the channel gain, the method further comprises quantizing the channel gain to a value of a preset phase and/or amplitude.

The transmission power adjustment method according to claim 2, wherein after obtaining the actual transmission power of the respective time-frequency block signals, respectively, according to the original transmission power and the actual transmission power of the respective time-frequency block signals, respectively The total original transmit power and the total actual transmit power are calculated. If the total actual transmit power is greater than the total original transmit power, a normalization operation is performed on the actual transmit power of the respective time-frequency blocks.

The transmission power adjustment method according to claim 5, wherein if the total actual transmission power is greater than the total original transmission power, a predetermined number of normalization operations are performed.

The method for adjusting a transmit power according to claim 5, wherein if the total actual transmit power is greater than the total original transmit power, and the ratio of the total actual transmit power to the total original transmit power is less than a preset threshold, Then, the actual transmission power is directly used for signal transmission, otherwise the actual transmission power normalization operation is performed.

The transmission power adjustment method according to claim 5 or 6 or 7, wherein the normalization operation is to multiply the actual transmission power of each time-frequency block signal by an adjustment coefficient to obtain a new one. Actual transmit power.

The transmission power adjustment method according to claim 8, wherein the adjustment coefficient is calculated as: ∑I ^T «IZ∑l ^S 'j | , where δ represents an adjustment coefficient, and Tij represents each time The actual transmit power of the frequency block, S ij represents the original transmit power of each time-frequency block, i represents the sequence number of the sub-carrier of the resource block occupied by the transmit signal, j represents the symbol of the resource block occupied by the transmit signal, and i and j are natural numbers.

10. The method according to claim 1, further comprising:

If it is judged whether the channel transmitted by the signal satisfies the coherent condition, the power adjustment operation is performed, otherwise the original transmission power is directly used for signal transmission.

The method for adjusting a transmit power according to claim 10, wherein the determining whether the channel transmitted by the signal satisfies the coherent condition comprises:

Determining whether the speed of the terminal exceeds a speed threshold, and if it exceeds, the coherent condition is not satisfied; or

Determining whether a variation amplitude of a channel gain value of each time-frequency block signal exceeds an amplitude threshold, and if it exceeds, a coherent condition is not satisfied; or

It is judged whether the number of consecutive changes of the sign of the real part or the imaginary part of the channel gain value of each time-frequency block signal exceeds the number of times threshold, and if it exceeds, the coherent condition is not satisfied.

12. A transmit power adjustment device, comprising:

The transmission power adjusting device according to claim 12, wherein the transmitting The power adjustment module further includes a calculation module, and is connected to the channel gain obtaining module, configured to divide the original transmit power of the respective time-frequency block signals by the channel gain, to obtain an actual transmit power of each new time-frequency block signal. .

The transmit power adjustment device according to claim 13, wherein the transmit power adjustment module further includes a transmit power determining module, configured to determine whether an actual transmit power of each time-frequency block signal conforms to a preset Range, if the actual transmit power of the time-frequency block signal is not within the preset range, the predetermined transmit power value is used as the actual transmit power of the time-frequency block signal.

The transmission power adjustment apparatus according to claim 13 or 14, wherein the transmission power adjustment module further comprises a quantization module, configured to quantize the channel gain to a preset phase and/or amplitude value. .

The transmit power adjustment device according to claim 13, wherein the transmit power adjustment module further includes:

a total original power calculation module, configured to be connected to the calculation module, configured to calculate a total original transmit power according to an original transmit power of each of the time-frequency block signals;

And a total actual transmit power module, configured to be connected to the calculation module, configured to calculate a total actual transmit power according to an actual transmit power of each time-frequency block signal;

a normalization module, configured to be connected to the total original power calculation module and the total actual transmit power module, after obtaining the actual transmit power of the respective time-frequency block signals, if the total actual transmit power is greater than the total original transmit power And normalizing the actual transmit power of each time-frequency block.

The transmitting power adjusting device according to claim 12, further comprising a coherent condition determining module, connected to the channel gain obtaining module and the transmit power adjusting module, configured to determine whether the channel transmitted by the signal satisfies a coherent condition , Yes, the adjustment operation is performed, otherwise the original transmission power is directly used for signal transmission.

A time division duplex system, comprising: at least one transmit power adjustment device, wherein the transmit power adjustment device is configured to obtain a channel gain value of each time-frequency block signal according to the downlink pilot signal, according to the channel gain The values are adjusted for the original transmit power of the respective time-frequency block signals to obtain the actual transmit power of the respective time-frequency block signals.