WO2012093454A1

WO2012093454A1 - Transmission device and transmission method

Info

Publication number: WO2012093454A1
Application number: PCT/JP2011/007216
Authority: WO
Inventors: 星野　正幸; 岩井　敬; 西尾　昭彦; 辰輔高岡; 今村　大地
Original assignee: パナソニック株式会社
Priority date: 2011-01-07
Filing date: 2011-12-22
Publication date: 2012-07-12

Abstract

A transmission device that allows degradation in SINR measurement accuracy due to a TPC error in a base station to be prevented even in an instance in which a different number of antenna ports is set for the transmission of each upstream signal. In this device, a transmission power controller (109) controls the transmission power of a signal. Here, the transmission power controller (109) controls the transmission power on the basis of a comparison between at least one number of antenna ports and the number of antenna ports used in the preceding transmission. Transmission RF units (111-1) and (111-2) transmit the signal through at least one antenna port at the controlled transmission power.

Description

Transmitting apparatus and transmitting method

The present invention relates to a transmission device and a transmission method.

In the uplink from the terminal (UE: User Equipment) to the base station (BS (Base Station) or eNB) in the cellular communication system, information transmission using a plurality of antenna ports (multi-antenna) is performed on the transmission / reception side. It is being considered. This is called MIMO (Multiple Input Multiple Output) transmission technology in the uplink. The uplink MIMO transmission technology is expected to improve performance in terms of both an increase in cell radius by beamforming and an increase in data rate by spatial multiplexing.

Further, various signals (uplink signals) transmitted on the uplink channel (uplink channel) of the cellular communication system include, for example, Periodic Sounding Reference Signal (hereinafter referred to as P-SRS), Aperiodic SRS (hereinafter referred to as A-). SRS), a signal transmitted on an uplink control channel (PUCCH: Physical-Uplink-Control-CHannel) (uplink control signal; hereinafter referred to as PUCCH signal), and an uplink data channel (PUSCH: Physical-Uplink-Shared-CHannel) (Uplink data signal; hereinafter referred to as a PUSCH signal). P-SRS is a channel quality measurement reference signal transmitted periodically. A-SRS is a channel quality measurement reference signal transmitted aperiodically in response to an instruction from the base station. Further, the PUCCH is a control channel for transmitting a response signal (ACK / NACK signal) corresponding to a demodulation result of downlink data (link from the base station to the terminal, downlink), downlink channel quality information, or the like. It is. The PUSCH is a data channel for transmitting uplink data (uplink data).

Requirement for these upstream signals is different. Therefore, when the terminal has a plurality of antenna ports, when setting how many antenna ports to use for transmission of each uplink signal, rather than setting the number of antenna ports in common for all channels, It is desired to set each uplink signal individually and to have flexibility.

On the other hand, the above-described reference signal (P-SRS or A-SRS) and data need to be related to each other. For example, the base station applies frequency resource allocation based on the result of observing the P-SRS transmitted from the terminal, sets the frequency resource used for transmitting the PUSCH signal (uplink data) of the terminal, and Apply precoding control based on Codebook to control the beam in a closed loop. Thereby, an effect of increasing SINR (Signal-to-Interference-and-Noise-Ratio) can be expected.

In addition, when the number of antenna ports smaller than the number of antenna ports included in the terminal is set for transmission of a certain uplink signal, the terminal has more than the set number of antenna ports under its own responsibility. The uplink signal can be transmitted using the antenna port.

For example, for a terminal having two antenna ports, a case where one antenna port is set for P-SRS transmission and two antenna ports are set for A-SRS transmission will be described. In this case, as shown in FIG. 1, the terminal allocates the P-SRS to each physical antenna (Physical antenna) using ImplementationIbased precoding when transmitting P-SRS (for example, using one antenna port 10). Can do. Thus, although each physical antenna is handled as a single antenna port as a system, two physical antennas can be used from the viewpoint of using the physical antenna of the terminal. As an example of Implementation based precoding, the operation using only the antenna port that observed a strong signal (signal with good reception quality) based on the observation result of the downlink signal, or the power distribution according to the ratio of the received power The operation to do is mentioned.

In the uplink of 3GPP LTE (3rd Generation Partner Project Long Term Evolution, hereinafter referred to as LTE), only a terminal having one antenna port is supported. For example, in LTE, the transmission power P _SRS (i) of the reference signal (SRS) in sub-frame #i is obtained according to the following equation (1) as described in Non-Patent Document 1.

In Expression (1), P _CMAX [dBm] indicates the maximum transmission power of the SRS that can be transmitted by the terminal. Moreover, P _{SRS_OFFSET} [dBm] indicates an offset value (parameter set from the base station) with respect to the transmission power of PUSCH transmitted by the terminal. M _SRS indicates the number of frequency resource blocks allocated to the SRS. P _{O_PUSCH} [dBm] indicates an initial value of PUSCH transmission power (a parameter set from the base station). PL represents a path loss level [dB] measured by the terminal. Further, α represents a weighting coefficient (a parameter set from the base station) representing a compensation ratio of path loss (PL). Further, f (i) is a subframe #i including a past value of a TPC (Transmission Power Control) command (control value, for example, +3 dB, +1 dB, 0 dB, −1 dB) to be closed loop control (closed loop control). The cumulative value at.

Similarly, transmission powers P _PUCCH (i) and P _PUSCH (i) for the uplink control channel (PUCCH) and uplink data channel (PUSCH) in sub-frame #i are expressed by the following equations (2), (3 ) Respectively.

In Expression (2), P _{O_PUCCH} [dBm] indicates an initial value of PUCCH transmission power (a parameter set by the base station). Further, h (n _CQI , n _HARQ ) and Δ _{F_PUCCH} (F) indicate parameters set according to the format type and the number of bits of PUCCH. Further, g (i) indicates the cumulative value in subframe #i including the past value of the TPC command to be closed-loop controlled, similarly to f (i) in Expression (1). In Equation (3), M _PUSCH (i) indicates the number of PUSCH frequency resource blocks allocated in subframe #i. P _{O_PUSCH} (j) [dBm] and α (j) indicate the initial value of the transmission power of PUSCH and the weighting coefficient indicating the compensation ratio of the path loss (PL), respectively, and are quasi-fixed allocation (j = 0) And parameters set individually from the base station according to the type of dynamic allocation (j = 1). Δ _TF (i) indicates an offset value that can be set according to the amount of control information when transmitting control information using PUSCH.

Also, in the LTE-Advanced uplink, which is an extension of LTE, a terminal having a plurality of antenna ports is supported as in the above-described MIMO transmission in the uplink. In LTE-Advanced, it is considered to perform common transmission power control between antenna ports as uplink signal transmission power control (TPC control) (see, for example, Non-Patent Document 2). Specifically, the same value is applied to the parameter and TPC command used in Equation (1) regardless of the antenna port. Similarly, it is conceivable to apply common transmission power control between antenna ports for PUCCH (Equation (2)) and PUSCH (Equation (3)). Thereby, it is possible to prevent an increase in the amount of signaling required for transmission power control in a terminal having a plurality of antenna ports.

On the other hand, from the viewpoint of implementing a power amplifier (PA) in the terminal, an error in TPC control (an error between a target transmission power set in the terminal and a transmission power actually used by the terminal during transmission. Called). The point to consider regarding the TPC error is that the TPC error becomes larger as the transmission time interval of the upstream signal is longer. Specifically, since the temperature of the terminal PA changes with the passage of time, the amplification characteristics of the PA change with the passage of time. Therefore, the longer the uplink signal transmission time interval, the greater the degree of change in the PA amplification characteristics at the terminal. That is, it is assumed that the TPC error becomes larger as the uplink signal transmission time interval is longer.

Another point to be considered regarding the TPC error is that the TPC error becomes larger as the transmission power change amount (hereinafter referred to as ΔP) from the previous transmission (at the time of the previous transmission) is larger. In a terminal in which a multi-stage PA is mounted as an amplifier circuit, an increase or decrease in the number of PA stages used when amplifying transmission power increases as ΔP increases. That is, the increase / decrease in the number of stages of PA increases as ΔP increases, so the error in each stage of PA is added, and the TPC error becomes larger. Further, since the transmission power is proportional to the frequency bandwidth of the transmission signal, the greater the ΔP (the greater the increase / decrease in transmission power), the greater the change in the frequency position and bandwidth of the transmission signal. That is, since the PA amplification characteristic also depends on the frequency (frequency position and bandwidth), the larger the ΔP (the greater the increase / decrease in the frequency position and bandwidth), the greater the TPC error.

In LTE, an allowable range of TPC error depending on the transmission time interval of SRS and the transmission power change amount (ΔP) is defined (for example, see Non-Patent Document 3). FIG. 2 shows the definition of the allowable range of TPC error when the elapsed time (transmission gap) from the previous uplink signal transmission is longer than 20 ms (transmission gap> 20 ms). That is, as shown in FIG. 2, when the elapsed time is longer than 20 ms, a TPC error within a range of ± 9.0 dB is allowed. FIG. 3 shows the definition of the allowable range of the TPC error when the elapsed time from the previous uplink signal transmission is 20 ms or less (transmission gap ≤ 20 ms). As shown in FIG. 3, when the elapsed time is within 20 ms, the allowable range of the TPC error is larger as the transmission power change amount (power step) ΔP is larger.

Here, if the SNR SINR measurement error deteriorates due to the TPC error, the base station cannot perform PUSCH frequency resource allocation, MCS selection, and the like with high accuracy, and the system performance deteriorates. Therefore, in order to prevent the degradation of SINR measurement accuracy due to the TPC error, it is conceivable to set the SRS transmission power in consideration of the assumed TPC error of the terminal. That is, the terminal sets the transmission power of the SRS larger than the target transmission power in consideration of the assumed maximum TPC error variation. For example, the terminal increases the value of the offset value P _{SRS_OFFSET} with respect to the PUSCH transmission power shown in Equation (1) by the amount of the assumed maximum TPC error variation. As a result, even when the SRS transmission power control of the terminal is affected by the TPC error, the SRS received SINR (input SINR) in the base station does not fall into a degraded region (for example, 0 dB or less) due to the TPC error. And deterioration of SINR measurement accuracy (channel quality measurement accuracy) can be prevented.

When the transmission power control in the above prior art is applied to MIMO transmission as it is, the following problems arise.

Specifically, during MIMO transmission, as described above, a different number of antenna ports can be set for each uplink signal, so that a continuous uplink signal (for example, the uplink signal transmitted immediately before and the uplink signal transmitted this time) Even if the transmission time interval is within 20 ms, the number of antenna ports used when transmitting each uplink signal may be different. Therefore, when a different number of antenna ports is set for each uplink signal and the allowable range of the TPC error is defined in the same manner as in the prior art (for example, FIG. 2 and FIG. 3), the allowable error in transmission power control is defined. In some cases, the uplink signal transmission time interval cannot be properly specified.

For example, as shown in FIG. 4, the terminal has two antenna ports, one antenna port (Port 10) is set for PUCCH signal transmission, and two antenna ports (Port 20, 21) for P-SRS transmission. The case where is set will be described. Also, as shown in FIG. 4, the PUCCH signal is transmitted at time t1 (previous transmission), the P-SRS is transmitted at time t2 (current transmission), and each uplink signal is transmitted from time t1 to time t2. Assume that the elapsed time (transmission time interval) T is up to 20 ms. Here, a case where the elapsed time (transmission time interval) T is 20 ms or less is a case where the TPC error is small, and a case where the elapsed time T is longer than 20 ms is a case where the TPC error is large.

In FIG. 4, the transmission time interval T (= time t2−time t1) is within 20 ms. Therefore, according to the transmission power setting of the prior art (for example, FIG. 3), the allowable range of TPC error is set to a smaller value compared to the case where the transmission time interval is larger than 20 ms (for example, FIG. 2), and the time t2 The transmission power of the P-SRS transmitted in is not set large (that is, the transmission power of the P-SRS is set small). However, as shown in FIG. 4, the set number of antenna ports differs between the PUCCH signal transmitted at time t1 and the P-SRS transmitted at time t2. For this reason, of the two antenna ports provided in the terminal, one antenna port is not used during transmission of the PUCCH signal (that is, during previous transmission). That is, since the terminal does not consider the transmission time interval at the antenna port that was not used at the previous transmission, the TPC error of the PA corresponding to the antenna port becomes large.

An object of the present invention is to provide a transmission apparatus and a transmission method capable of preventing deterioration of SINR measurement accuracy due to a TPC error in a base station even when different numbers of antenna ports are set for transmission of each uplink signal. is there.

A transmission apparatus according to an aspect of the present invention includes a control unit that controls transmission power of a signal, and a transmission unit that transmits the signal through at least one antenna port with the controlled transmission power. Then, the control unit controls the transmission power based on a comparison between the number of the at least one antenna port and the number of antenna ports used for the previous transmission.

A transmission method according to an aspect of the present invention is a transmission method that controls transmission power of a signal, and transmits the signal through the at least one antenna port with the controlled transmission power. The transmission power is controlled based on a comparison between the number of one antenna port and the number of antenna ports used for the previous transmission.

According to the present invention, even when different numbers of antenna ports are set for transmission of each uplink signal, it is possible to prevent deterioration in SINR measurement accuracy due to TPC errors in the base station.

The figure which shows the setting and precoding processing of the number of antenna ports The figure which shows a response | compatibility with the transmission time interval and the allowable range of TPC error The figure which shows a response | compatibility with a transmission time interval, transmission power variation | change_quantity, and the allowable range of TPC error Diagram for explaining the problems of the prior art The block diagram which shows the main structures of the terminal which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. The figure which shows the example of a setting of the transmission power offset value which concerns on Embodiment 1 of this invention. The figure which shows the response | compatibility with the magnitude relationship of the transmission time interval T and antenna port number, and offset correction value which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 2 of this invention. The figure which shows the example of a setting of the transmission power offset value which concerns on Embodiment 2 of this invention. The figure which shows the response | compatibility with the format type of the transmission time interval T and PDCCH and offset correction value which concern on Embodiment 2 of this invention. The figure which shows the closed-loop MIMO control by Fallback using DCI | format | 0 in Embodiment 2 of this invention The block diagram which shows the structure of the terminal which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 3 of this invention. The figure which shows the example of a setting of the transmission power offset value which concerns on Embodiment 3 of this invention. The figure which shows a response | compatibility with the ratio of the transmission bandwidth which concerns on Embodiment 3 of this invention, and an additional offset amount

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In each embodiment of the present invention, P-SRS, A-SRS, PUCCH signal, and PUSCH signal will be described as uplink signals, but the uplink signals are not limited to these.

Also, the number of antenna ports used for transmission of P-SRS, A-SRS, PUCCH signal, and PUSCH signal is individually set. It is assumed that the number of antenna ports for each uplink signal is set semi-static and does not change for several hundred milliseconds to several seconds. That is, here, the number of antenna ports used for transmission of the uplink signal is specified by the type of the uplink signal.

(Embodiment 1)
FIG. 5 shows the main configuration of the terminal according to the present embodiment. In terminal 100 shown in FIG. 5, transmission power control section 109 controls uplink signal transmission power, and transmission RF sections 111-1 and 111-2 control uplink power with at least one antenna port. To send through. Here, the transmission power control unit 109 controls the transmission power based on a comparison between the number of the at least one antenna port and the number of antenna ports used for the previous transmission.

FIG. 6 shows the configuration of terminal 100 according to the present embodiment. In terminal 100 shown in FIG. 6, transmission processing sections 101-1 and 101-2 are provided corresponding to the number of antenna ports that can be used in terminal 100, respectively. Further, the transmission RF units 111-1 and 111-2 are provided according to the number of antennas 112-1 and 112-2 (physical antennas), respectively. That is, here, as shown in FIG. 6, terminal 100 can transmit a signal using a maximum of two antenna ports. In addition, terminal 100 includes two PAs corresponding to antennas 112-1 and 112-2, respectively. One antenna port is assumed to be composed of one or a plurality of physical antennas.

Each transmission processing unit 101 mainly includes a generation unit 102, a mapping unit 103, an IFFT (InverseInFourier Transform) unit 104, a CP (Cyclic Prefix) addition unit 105, and a transmission power control unit 109. .

The generation unit 102 generates an uplink signal transmitted from the terminal 100, and outputs the generated uplink signal to the mapping unit 103. For example, when generating P-SRS or A-SRS as a reference signal, the generation unit 102 generates an RS sequence (for example, a ZC (Zadoff-Chu) sequence), and a cyclic shift amount (indicated by the base station) A phase rotation corresponding to CS (Cyclic Shift) amount is given to the RS series. For example, when generating the PUCCH signal as the control signal, the generation unit 102 performs channel coding on a CQI (Channel Quality Indicator) report signal or an HARQ (Hybrid Automatic Transmission Request) ACK / NACK signal, etc. And apply modulation. Further, when generating the PUSCH signal as uplink data (data signal), the generation unit 102 uses the transport block size, the coding rate, and the modulation scheme instructed by the base station for the uplink data, respectively. Encode, rate match and modulate.

Mapping section 103 maps the signal (RS sequence, control signal, or uplink data) input from generation section 102 to the frequency resource based on the frequency resource allocation information instructed from the base station, and outputs it to IFFT section 104 .

The IFFT unit 104 performs IFFT processing on the signal input from the mapping unit 103, and outputs the signal after IFFT processing to the CP adding unit 105.

CP adding section 105 adds the same signal as the tail part of the signal after IFFT inputted from IFFT section 104 to the head as CP, and outputs the signal after CP addition to transmission power control section 109.

The offset setting unit 106 includes a calculation unit 107 and an offset value determination unit 108.

Specifically, the calculation unit 107 of the offset setting unit 106 starts from the transmission time of the uplink signal (PUSCH signal, PUCCH signal, or SRS (P-SRS, A-SRS)) transmitted immediately before (previous transmission) by the terminal 100. The elapsed time of is calculated. The calculation unit 107 also calculates the number of antenna ports used when transmitting the uplink signal transmitted immediately before (previous transmission) at the terminal 100 and the number of antenna ports used when transmitting the uplink signal transmitted this time from the terminal 100. Calculate the magnitude relationship. Then, the calculating unit 107 outputs the calculated relationship between the elapsed time and the number of antenna ports to the offset value determining unit 108.

The offset value determination unit 108 of the offset setting unit 106 is used when setting the transmission power of the uplink signal transmitted from the terminal 100 according to the magnitude relationship between the elapsed time input from the calculation unit 107 and the number of antenna ports. An offset value for the transmission power of the uplink signal (hereinafter referred to as a transmission power offset value. For example, P _{SRS_OFFSET} shown in Expression (1)) is set. Then, offset value determination section 108 outputs the transmission power offset value to transmission power control section 109. Details of the transmission power offset value setting process in offset setting section 106 will be described later.

Transmission power control section 109 controls the transmission power of the signal (uplink signal) input from CP adding section 105 according to the transmission power offset value input from offset value determination section 108, and pre-transmits the signal after the transmission power control. Output to coding section 110.

The precoding unit 110 performs precoding processing on the signals input from the transmission processing units 101-1 and 101-2 (that is, signals corresponding to the respective antenna ports) in the same manner as in FIG. For example, when transmitting a signal using one antenna port, the precoding unit 110 distributes the signal to each physical antenna using Implementation based precoding. In this case, the signal is transmitted by the two antennas 112-1 and 112-2. In addition, a signal that does not support precoding among signals using one antenna port is not subjected to precoding processing. In this case, the signal is transmitted from either one of the two antennas 112-1 and 112-2. That is, when transmitting a signal using one antenna port, one of the two antennas 112-1 and 112-2 provided in the terminal 100 (that is, one of the two PAs) cannot be used. . In addition, the precoding unit 110 performs codebook-based precoding on signals transmitted through a plurality of antenna ports (two antenna ports). Then, precoding section 110 outputs the precoded signal to transmission RF sections 111-1 and 111-2, respectively.

The transmission RF unit 111 performs transmission processing such as D / A conversion, up-conversion, and amplification on the signal input from the precoding unit 110, and transmits the signal after the transmission processing from the antenna 112. Thus, in terminal 100, the uplink signal is transmitted via at least one antenna port with the transmission power controlled by transmission power control section 109.

Next, FIG. 7 shows the configuration of base station 200 according to the present embodiment. In the base station 200 shown in FIG. 7, the reception RF unit 202 receives a signal transmitted from the terminal 100 (FIG. 6) via the antenna 201, and performs reception processing such as down-conversion and A / D conversion on the received signal. I do. The signal transmitted from terminal 100 includes each uplink signal (for example, PUCCH signal, PUSCH signal, or SRS (P-SRS, A-SRS)). Then, reception RF section 202 outputs the signal after reception processing to CP removal section 203.

CP removing section 203 removes the CP added to the head of the signal inputted from reception RF section 202 and outputs the signal after CP removal to FFT (Fast Fourier Transform) section 204.

The FFT unit 204 performs an FFT process on the signal input from the CP removal unit 203 to convert the signal into a frequency domain signal, and outputs the frequency domain signal to the demapping unit 205.

Based on the frequency resource allocation information for the desired terminal, which is instructed by the base station 200 to the terminal 100 (the desired terminal that is the communication target), the demapping unit 205 determines the desired value from the frequency domain signal input from the FFT unit 204. A signal corresponding to the transmission band (frequency resource) of the terminal is extracted. Then, the demapping unit 205 outputs the extracted signal (SRS, PUCCH signal, or PUSCH signal) to the corresponding components of the SRS SINR measurement unit 208, the PUCCH resource detection unit 210, and the PUSCH demodulation unit 212, respectively. To do.

The cyclic shift amount setting unit 206 outputs the cyclic shift amount for the desired terminal, which is instructed by the base station 200 to the terminal 100 (desired terminal), to the SRS SINR measurement unit 208.

The offset setting unit 207 performs the same processing as the offset setting unit 106 of the terminal 100. That is, the offset setting unit 207 includes the elapsed time from the transmission time of the uplink signal transmitted immediately before (previous transmission) from the terminal 100 (desired terminal), and the number of antenna ports between the previous transmission and the current transmission. The transmission power offset value for each uplink signal is set according to the magnitude relationship. Then, offset setting section 207 outputs the set transmission power offset value to data SINR derivation section 209, PUCCH demodulation section 211, and PUSCH decoding section 213, respectively.

SIRS measurement unit for SRS 208 complex-divides the SRS (P-SRS or A-SRS) input from demapping unit 205 and the RS sequence known between transmission and reception to obtain a correlation signal in the frequency domain. . Furthermore, the SNR SINR measurement unit 208 performs an IDFT (Inverse Discrete Fourier Transform) process on the frequency domain correlation signal to calculate a time domain correlation signal (that is, a delay profile). This delay profile includes SRSs (reference signals) of a plurality of terminals. Therefore, the SIRS SINR measurement unit 208 uses the cyclic shift amount of the desired terminal input from the cyclic shift amount setting unit 206 to mask other than the portion corresponding to the cyclic shift amount of the desired terminal in the delay profile. Thus, the SNR SINR measurement value (SRS SINR measurement value) of the desired terminal is calculated. Then, the SRS SINR measurement unit 208 outputs the calculated SRS SINR measurement value to the data SINR deriving unit 209.

The data SINR deriving unit 209 uses the SRS SINR measurement value input from the SRS SINR measurement unit 208 and the transmission power offset value input from the offset setting unit 207 to perform uplink data (that is, PUSCH signal). SINR (data SINR measurement value) is derived. Specifically, the data SINR derivation unit 209 derives the data SINR measurement value according to the following equation (4) using the SRS SINR measurement value and the transmission power offset value.

The base station 200 performs scheduling (for example, frequency resource allocation and MCS selection) of the terminal 100 using the data SINR measurement value derived by the data SINR deriving unit 209.

The PUCCH resource detection unit 210 performs despreading processing on the PUCCH signal input from the demapping unit 205 using the cyclic shift amount and spreading code assigned to the desired terminal, and assigns the PUCCH signal from the desired terminal. The detected PUCCH resource is detected. When the PUCCH signal from the desired terminal can be detected, the PUCCH resource detection unit 210 outputs the PUCCH signal to the PUCCH demodulation unit 211.

The PUCCH demodulation unit 211 performs demodulation processing on the PUCCH signal input from the PUCCH resource detection unit 210, and extracts the demodulated PUCCH signal as a PUCCH demodulated signal.

The PUSCH demodulation unit 212 performs demodulation processing on the PUSCH signal input from the demapping unit 205 based on the modulation scheme instructed to the desired terminal, and outputs the demodulated PUSCH signal to the PUSCH decoding unit 213.

The PUSCH decoding unit 213 performs a decoding process on the PUSCH signal input from the PUSCH demodulating unit 212 based on the coding rate instructed to the desired terminal, and extracts the decoded PUSCH signal as PUSCH decoded data.

Next, details of transmission power offset value setting processing in the offset setting unit 106 (FIG. 6) of the terminal 100 and the offset setting unit 207 (FIG. 7) of the base station 200 will be described.

Here, the case where the elapsed time (transmission time interval) T from the transmission time of the uplink signal transmitted last time to the transmission time of the uplink signal transmitted this time is 20 ms or less is defined as the case where the TPC error is small, and the elapsed time T is 20 ms. A longer case is a case where the TPC error is large.

8A and 8B, a case where a PUCCH signal is transmitted at time t1 and P-SRS is transmitted at time t2 after time t1 will be described. 8A and 8B, it is assumed that the elapsed time (transmission time interval) T from time t1 to time t2 is within 20 ms (T ≦ 20 ms).

In FIG. 8A, one antenna port (Port 10) is set for transmission of the PUCCH signal, and two antenna ports (Port 20, 21) are set for transmission of the P-SRS. On the other hand, in FIG. 8B, two antenna ports (Port 20, 21) are set for PUCCH signal transmission, and one antenna port (Port 10) is set for P-SRS transmission. When one antenna port is used, at least one of the antennas 112-1 and 112-2 of the terminal 100 is used. When two antenna ports are used, the antenna 112- of the terminal 100 is used. Both 1 and 112-2 are used.

The calculation unit 107 of the offset setting unit 106 transmits the transmission time of the current upstream signal (P-SRS in FIGS. 8A and 8B) from the transmission time t1 of the previous upstream signal (PUCCH signal in FIGS. 8A and 8B). An elapsed time (transmission time interval) T (= time t2−time t1) until t2 is calculated.

Also, the calculation unit 107 calculates the magnitude relationship between the number of antenna ports used for transmission at time t1 and the number of antenna ports used for transmission at time t2. That is, the calculation unit 107 compares the number of antenna ports (at least one antenna port) used during the current transmission with the number of antenna ports used for the previous transmission. For example, in FIG. 8A, the calculation unit 107 calculates that the number of antenna ports (one) used at time t1 is smaller than the number of antenna ports (two) used at time t2. On the other hand, in FIG. 8B, the calculation unit 107 calculates that the number of antenna ports (two) used at time t1 is larger than the number of antenna ports (one) used at time t2.

Offset value determination unit 108, based on the calculated transmission time interval T and the magnitude relationship of the number of antenna ports at the calculator 107, for example, according to the table shown in FIG. 9, determines a correction value delta _offset. Here, for example, the transmission power P _SRS (i) of _SRS in sub-frame #i is obtained according to the following equation (5).

In Expression (5), P _CMAX [dBm] represents the maximum transmission power of the SRS that can be transmitted by the terminal 100. P _{SRS_OFFSET} [dBm] indicates a transmission power offset value (a parameter set from base station 200) with respect to the transmission power of PUSCH transmitted by terminal 100. M _SRS indicates the number of frequency resource blocks allocated to the SRS. P _{O_PUSCH} [dBm] indicates an initial value of PUSCH transmission power (a parameter set by the base station 200). PL represents a path loss level [dB] measured by the terminal 100. Further, α represents a weighting factor (a parameter set from the base station 200) indicating a compensation rate of path loss (PL). Further, f (i) indicates a cumulative value in subframe #i including a past value of a TPC command (control value, for example, +3 dB, +1 dB, 0 dB, −1 dB) controlled in a closed loop. Further, in the equation (3), the delta _offset, associated with the calculation unit 107 the elapsed time calculated in (transmission time interval), indicating the correction value of the offset value P _{SRS_OFFSET.}

That is, offset value determination section 108 sets correction value Δ _offset for correcting transmission power offset value P _{SRS_OFFSET} instructed from base station 200 based on transmission time interval T. Then, the offset value determining unit 108 determines the corrected transmission power offset value (P _{SRS_OFFSET} + Δ _offset ) by adding the correction value Δ _offset to the transmission power offset value P _{SRS_OFFSET} as shown in the equation (5). .

Then, transmission power control section 109 controls transmission power P _SRS (i) of _SRS according to equation (5) using transmission power offset value (P _{SRS_OFFSET} + Δ _offset ) input from offset value determination section 108. . That is, the transmission power control section 109 controls the transmission power of the uplink signal by increasing or decreasing the offset value (P _{SRS_OFFSET} + Δ _offset ) with respect to the transmission power.

The following describes configuration examples of a correction value delta _offset.

For example, in FIG. 8A, since the number of antenna ports used is one at time t1, PA corresponding to one of the two antennas 112-1 and 112-2 provided in terminal 100 is used. Can be turned off. On the other hand, in FIG. 8A, at time t2, since the number of antenna ports used is two, signals are transmitted by all PAs corresponding to the two antennas 112-1 and 112-2 provided in terminal 100. The Therefore, in the PA corresponding to the antenna used also at time t1 out of the two antennas included in terminal 100 at time t2, the uplink signal transmission time interval T (= time t2−time t1) is a predetermined threshold (20 ms). However, in the PA that can be turned off at time t1, the transmission time interval T of the upstream signal may be longer than a predetermined threshold (20 ms). That is, one of the two antennas used at time t2 may not be used at time t1, and the transmission time interval T of the uplink signal at the antenna is the transmission at the other antenna. It can be considered that it is longer than the time interval T (= time t2−time t1). That is, it can be considered that the TPC error in the PA corresponding to the antenna not used at time t1 is large.

Therefore, as shown in FIG. 8A, even if the transmission time interval T is within 20 msec, the number of antenna ports (one) used at time t1 is the antenna used for transmission of the uplink signal transmitted at time t2. When the number is smaller than the number of ports (two), the assumed TPC error is large.

Also, when the transmission time interval T is longer than 20 ms (not shown), the TPC error is large.

Therefore, as shown in FIG. 9, when the transmission time interval T is longer than 20 msec (not shown), or the offset value determination unit 108 has the number of antenna ports used for transmission of the uplink signal transmitted at time t1. If less than the number of antenna ports used for transmission of an uplink signal to be transmitted at time t2 (FIG. 8A), to set the correction value delta _offset to 0 dB.

On the other hand, in FIG. 8B, at time t2, since the number of antenna ports used is one, either one of the two antennas 112-1 and 112-2 provided in terminal 100 is connected. The corresponding PA can be turned off. On the other hand, in FIG. 8B, at time t1, since the number of antenna ports used is two, signals are transmitted by all PAs corresponding to the two antennas 112-1 and 112-2 provided in terminal 100. The Therefore, at time t2, even if the PA corresponding to any antenna is turned OFF, the transmission time interval T (= time t2) of the signal transmitted using the PA corresponding to the antenna used for P-SRS transmission -Time t1) is within a predetermined threshold (20 ms). That is, as shown in FIG. 8B, one antenna used at time t2 is always used at time t1, and the transmission time interval T (= time t2−time t1) of the uplink signal at the antenna is predetermined. It can be reliably regarded as being within the threshold (20 ms).

Therefore, as shown in FIG. 8B, the transmission time interval T is within 20 ms, and the number of antenna ports (two) used at time t1 is larger than the number of antenna ports (one) used at time t2. In many cases, the expected TPC error is small.

Therefore, as shown in FIG. 9, the offset value determination unit 108 has the transmission time interval T within 20 msec, and the number of antenna ports used for transmitting the uplink signal transmitted at time t1 is transmitted at time t2. When the number of antenna ports is larger than the number of antenna ports used for transmission of the uplink signal (FIG. 8B), the correction value Δ _offset is set to −6 dB.

Then, the offset value determination unit 108 determines the transmission power offset value (P _{SRS_OFFSET} + Δ _offset ) by adding the correction value Δ _offset to the offset value P _{SRS_OFFSET} instructed from the base station 200.

Further, in FIG. 8A and FIG. 8B, the case where transmission power control for SRS (P-SRS or A-SRS) is performed has been described. However, the offset setting unit 106 (offset value determining unit 108) also performs transmission power control for the PUCCH and PUSCH according to the following expressions (6) and (7): ) _Is added with a transmission power offset value _Δoffset .

That is, terminal 100 compares the number of antenna ports (at least one antenna port) used at the time of the current transmission with the number of antenna ports used for the previous transmission at a predetermined time interval (20 ms in this case) or less. Based on the above, the transmission power of the uplink signal is controlled. Specifically, when the transmission time interval T is short and the number of antenna ports is the same as or decreased from the previous transmission, the offset value determination unit 108 compares the transmission power offset with the other cases. The correction value Δ _offset is set so that the value (P _{SRS_OFFSET} + Δ _offset ) becomes smaller. The “when the transmission time interval T is short” is, for example, “when T ≦ 20 ms”. In addition, the above “when the number of antenna ports is the same as or decreased when the previous transmission” is, for example, “when the number of antenna ports used at time t2 ≦ the number of antenna ports used at time t1”. “Other than that” is, for example, “when T> 20 ms or when the number of antenna ports used at time t1 <the number of antenna ports used at time t2”.

That is, when the number of antenna ports (at least one antenna port) used for transmission of the uplink signal transmitted this time is smaller than the number of antenna ports used for the previous transmission, the transmission power control unit 109 The transmission power is controlled so that the transmission power of the signal is reduced. In other words, the transmission power control unit 109, when the antenna port (at least one antenna port) used for transmission of the uplink signal transmitted this time does not include the antenna port that was not used in the previous transmission, The transmission power is controlled so that the transmission power becomes smaller.

Thereby, it becomes possible to set the transmission power of the uplink signal low to the minimum necessary transmission power at which the base station 200 can obtain a desired reception SINR (a reception SINR that does not deteriorate the SINR measurement accuracy). Therefore, it is possible to suppress the power consumption at the terminal 100 to the minimum necessary while ensuring the SNR SINR measurement accuracy (channel quality accuracy) at the base station 200. Also, the terminal 100 can reduce inter-cell interference by suppressing the transmission power of SRS to the minimum necessary.

Further, the terminal 100 operates as follows even when the transmission time interval T is within a predetermined threshold (20 ms). That is, when the number of antenna ports used at time t1 is smaller than the number of antenna ports used at time t2, terminal apparatus 100 compares the number of antenna ports used at time t2 with the number of antenna ports used at time t1. The correction value Δ _offset is set so that the transmission power offset value (P _{SRS_OFFSET} + Δ _offset ) becomes large.

That is, when the number of antenna ports (at least one antenna port) used for transmission of the uplink signal transmitted this time is greater than the number of antenna ports used for the previous transmission, the transmission power control unit 109 The transmission power is controlled so that the transmission power of the signal is increased. In other words, the transmission power control unit 109, when the antenna port (at least one antenna port) used for transmission of the uplink signal transmitted this time includes an antenna port that was not used in the previous transmission, The transmission power is controlled so as to increase the transmission power.

That is, when the number of antenna ports used for the current transmission increases from the previous transmission, the terminal 100 considers the transmission time interval at the antenna port that was not used during the previous transmission (that is, during the previous transmission). Assuming that it is longer than the transmission time interval at the used antenna port), the transmission power of the uplink signal is set larger. As a result, an increase in the TPC error of the PA corresponding to the port that was not used at the previous transmission can be suppressed.

Similarly to the offset setting unit 106 of the terminal 100, the offset setting unit 207 of the base station 200 determines the transmission time interval of the uplink signal for each terminal 100 and the previous transmission time and the current transmission time for each terminal 100. A transmission power offset correction value _Δoffset is set based on the magnitude relationship between the number of antenna ports.

Thus, according to the present embodiment, the terminal varies the transmission power offset value for each uplink signal (PUCCH signal, PUSCH signal, and SRS) according to the transmission condition. Specifically, the terminal is based on the elapsed time from the previous transmission (transmission time interval) and the magnitude relationship between the number of transmission antenna ports used at the previous transmission and the number of transmission antenna ports used at the current transmission. Then, the transmission power offset value is set.

Accordingly, in a terminal having a plurality of antennas (for example, a terminal that performs MIMO transmission), even when a different number of antenna ports is set for each uplink signal, a TPC error based on the transmission time interval of the uplink signal using each antenna port. Can be identified appropriately. Therefore, according to the present embodiment, it is possible to prevent deterioration of SINR measurement accuracy due to a TPC error in the base station even when different numbers of antenna ports are set for transmission of each uplink signal.

Furthermore, according to the present embodiment, the terminal can control the transmission power of a channel that is expected to have a small TPC error to the minimum power necessary for obtaining a desired reception quality. Therefore, it is possible to suppress an increase in power consumption of the terminal and reduce inter-cell interference while preventing deterioration of SINR measurement accuracy due to a TPC error in the base station.

Further, in this embodiment, for example, when the correspondence between the magnitude relationship between the elapsed time T and the number of antenna ports shown in FIG. 9 and the correction value _Δoffset is defined in advance by the system, for transmission power control of the uplink signal Signaling for each transmission becomes unnecessary. Or, in the case of notifying in advance from the base station and the elapsed time T and the magnitude relationship between the number of antenna ports is shown in FIG. 9, the correspondence between the correction value delta _offset as a parameter to the terminal, the parameter is relatively long period, or The terminal only needs to be notified once, and signaling for each transmission for uplink signal transmission power control becomes unnecessary. Therefore, in these cases, an increase in signaling overhead required for uplink signal transmission power control can be suppressed.

In the present embodiment, as shown in FIG. 8A and FIG. 8B, the case where P-SRS is transmitted at time t2 and PUCCH is transmitted at time t1 has been described. However, terminal 100 uses the previous antenna (time t1) to transmit another uplink signal (PUSCH signal, PUCCH signal, P-SRS or A-SRS) different from the uplink signal (SRS) transmitted at time t2. Even when the transmission power of the uplink signal is controlled based on the comparison between the number of ports and the number of antenna ports used for transmission of the uplink signal transmitted this time (time t2), the same as in the present embodiment An effect can be obtained.

Further, in the present embodiment, the configuration in which base station 200 includes a single reception antenna has been described. However, base station 200 may have a configuration in which a plurality of reception antennas are provided, and components of each reception antenna may be demapped. After being taken out at 205, the SRS SINR measurement unit 208 may synthesize and perform TPC control.

(Embodiment 2)
In the present embodiment, a transmission power control method when a terminal transmits an A-SRS will be described.

The A-SRS is transmitted using control information transmitted from the base station to the terminal using a downlink control channel (PDCCH: Physical-Downlink-Control-CHannel) as a trigger. The PDCCH includes control information (data allocation information) related to PUSCH allocation, and the terminal transmits a PUSCH signal according to the instruction content (frequency resource or the like) from the base station indicated by the control information. That is, the PDCCH includes data allocation information related to PUSCH allocation and also includes a transmission request for A-SRS.

When a terminal receives a PDCCH, the A-SRS triggered by the PDCCH is transmitted after (or simultaneously with) the PUSCH signal transmitted according to the allocation by the PDCCH.

Therefore, in the present embodiment, for example, a case will be described in which a PUSCH signal is transmitted at time t1 and A-SRS is transmitted at time t2 after time t1. In the present embodiment, it is assumed that the number of antenna ports is defined semi-statically for A-SRS.

FIG. 10 shows the configuration of terminal 300 according to the present embodiment. In FIG. 10, the same components as those in the first embodiment (FIG. 6) are denoted by the same reference numerals, and the description thereof is omitted.

In terminal 300 shown in FIG. 10, PDCCH detection section 301 detects a downlink control channel (PDCCH) as control information (data allocation information) related to PUSCH allocation. When the PDCCH detection unit 301 detects control information related to PUSCH allocation, the PDCCH detection unit 301 outputs a transport block size, a coding rate, and a modulation scheme indicated by the base station, which are indicated in the control information, to the generation unit 102 (see FIG. Frequency resource allocation information is output to the mapping unit 103 (not shown).

Here, terminal 300 assumes two formats as the format of control information detected by PDCCH detection section 301 (sometimes referred to as DCI format). The first is control that can include information on the transport block size, coding rate, and modulation scheme while supporting codebook-based precoding as control information corresponding to transmission by a plurality of antenna ports. This is an information format (hereinafter referred to as Format 4 or sometimes referred to as DCIDformat 4). The second is a control information format that does not support precoding as control information corresponding to transmission by a single antenna and includes only one piece of information on a transport block size, a coding rate, and a modulation scheme (hereinafter referred to as “control information format”). , Called Format 0, or sometimes called DCI format 0).

The PDCCH detection unit 301 outputs information indicating whether the detected control information corresponds to Format IV4 or Format IV0 to the calculation unit 302 of the offset setting unit 106.

Similarly to the first embodiment, the calculation unit 302 of the offset setting unit 106 calculates the elapsed time from the transmission immediately before the uplink signal at the terminal 300, and transmits the uplink signal (PUSCH) transmitted immediately before (previous transmission) at the terminal 300. Signal) and the number of antenna ports used when transmitting the uplink signal (A-SRS) transmitted this time from terminal 300 is calculated.

However, in this embodiment, when calculating the magnitude relationship between the number of antenna ports, if the information input from the PDCCH detection unit 301 is Format 算出 4, the calculation unit 302 transmits two PUSCH signals transmitted last time. It is determined that the antenna port (that is, the maximum number of antenna ports that can be used in terminal 300) is used. On the other hand, when the information input from PDCCH detection unit 301 is Format 0, calculation unit 302 determines that only one antenna port is used for transmitting the previously transmitted PUSCH signal. As described above, the calculation unit 302 can specify the magnitude relationship between the number of antenna ports used for PUSCH signal transmission and the number of antenna ports used for A-SRS transmission based on the PDCCH format type. it can. Then, the calculating unit 302 outputs the calculated relationship between the elapsed time and the number of antenna ports to the offset value determining unit 303.

The offset value determination unit 303 determines the transmission power of the A-SRS according to the elapsed time (transmission time interval) and the size relationship of the number of antenna ports (or the PDCCH format type) input from the calculation unit 302. Set the offset value.

Next, FIG. 11 shows the configuration of base station 400 according to the present embodiment. In FIG. 11, the same components as those in the first embodiment (FIG. 7) are denoted by the same reference numerals, and the description thereof is omitted.

The base station 400 shown in FIG. 10 prepares at least two formats (DCI format) of control information used for PUSCH signal allocation, like the terminal 300 (FIG. 10). That is, the first is the above-described Format 4, and the second is the above-described Format 0.

The PDCCH generation unit 401 generates a PDCCH including control information used for PUSCH signal allocation. In addition, the PDCCH generation unit 401 outputs information indicating whether the control information used for PUSCH signal allocation corresponds to Format 4 or Format 0 to the offset setting unit 402.

The offset setting unit 402 performs the same processing as the offset setting unit 106 of the terminal 300. That is, the offset setting unit 402 includes an elapsed time from the transmission time of the PUSCH signal transmitted immediately before (previous transmission) from the terminal 300 (desired terminal), and information input from the PDCCH generation unit 401 (PDCCH format type). ) To determine a transmission power offset value for A-SRS. That is, offset setting section 402 determines that two antenna ports (all antenna ports included in terminal 300) have been used for PUSCH transmission when the information input from PDCCH generating section 401 is Format IV4. On the other hand, when the information input from PDCCH generation unit 401 is FormatＰＵ0, offset setting unit 402 determines that only one antenna port is used for PUSCH transmission. Then, offset setting section 402 calculates an offset value for the transmission power of A-SRS based on the determination result of the number of antenna ports used for PUSCH transmission.

The data SINR deriving unit 209 uses the A-SRS SINR measurement value input from the SRS SINR measurement unit 208 and the transmission power offset value for the A-SRS input from the offset setting unit 207 to perform uplink data In other words, the SINR (data SINR measurement value) of the PUSCH signal is derived. Specifically, the data SINR deriving unit 209 derives the data SINR measurement value according to the following equation (8) using the A-SRS SINR measurement value and the transmission power offset value.

The base station 400 performs scheduling of the terminal 300 (for example, frequency resource allocation and MCS selection) using the data SINR measurement value derived by the data SINR deriving unit 209.

Next, details of transmission power offset value setting processing in offset setting section 106 (FIG. 10) of terminal 300 and offset setting section 402 (FIG. 11) of base station 400 will be described.

Here, as in the first embodiment, the elapsed time (transmission time interval) T from the transmission time t1 of the uplink signal (PUSCH signal) transmitted last time to the transmission time t2 of the uplink signal (A-SRS) transmitted this time. Is a case where the TPC error is small, and a case where the elapsed time T is longer than 20 ms is a case where the TPC error is large.

12A and 12B, the elapsed time (transmission time interval) T from time t1 to time t2 is assumed to be within 20 ms (T ≦ 20 ms). Also, in FIG. 12A, PDCCH including control information related to PUSCH signal allocation is transmitted in Format （0 (DCI format 0), and in FIG. 12B, PDCCH including control information related to PUSCH signal allocation is Format 4 (DCI format 4). Sent by. 12A and 12B, two antenna ports (Ports 20 and 21) are set for A-SRS transmission.

Therefore, the PDCCH detection unit 301 of the terminal 300 outputs information indicating Format 0 to the calculation unit 302 in FIG. 12A, and outputs information indicating Format 4 to the calculation unit 302 in FIG. 12B.

The calculation unit 302 calculates the elapsed time (transmission time interval) T (= time t2−time t1) from the transmission time t1 of the PUSCH signal to the transmission time t2 of the A-SRS.

Further, the calculation unit 302 uses the number of antenna ports used for transmission at the time t1 (previous transmission) based on information input from the PDCCH detection unit 301 (information indicating Format 0 or Format 4), and time t2. The size relationship with the number of antenna ports used for transmission (current transmission) is calculated. That is, in FIG. 12A, the calculation unit 302 determines that the number of antenna ports used at time t1 is one because Format 0. Therefore, in FIG. 12A, the calculation unit 302 calculates that the number of antenna ports (one) used at time t1 is smaller than the number of antenna ports (two) used at time t2. On the other hand, in FIG. 12B, the calculation unit 302 determines that the number of antenna ports used at time t1 is two because Format 4. Therefore, in FIG. 12B, the calculation unit 302 calculates that the number of antenna ports (two) used at time t1 is the same as the number of antenna ports (two) used at time t2.

The offset value determination unit 303 determines the correction value Δ _offset based on the magnitude relationship between the transmission time interval T calculated by the calculation unit 107 and the number of antenna ports. In other words, in the present embodiment, offset value determination section 303 adjusts the correction value according to the table shown in FIG. 13 according to the transmission time interval T and the format of control information (data allocation information) related to PUSCH signal allocation. Determine _Δoffset . In the present embodiment, for example, the transmission power P _SRS (i) of the _SRS in sub-frame #i is obtained according to equation (5), as in the first embodiment.

For example, as shown in FIG. 12A, in the case of PUSCH signal allocation by Format 0, at time t1, PA corresponding to one of the two antennas 112-1 and 112-2 provided in terminal 300 is OFF. Can be. Therefore, the transmission time interval of the signal transmitted using the PA corresponding to one of the two antennas used at time t2 may be longer than (time t2−time t1). Therefore, the assumed TPC error is large in FIG. 12A.

On the other hand, as shown in FIG. 12B, in the case of PUSCH signal allocation by Format IV4, at time t1, signals are transmitted by all PAs corresponding to the two antennas 112-1 and 112-2 provided in terminal 300. Therefore, the transmission time interval T (= time t2−time t1) of signals transmitted using the PAs respectively corresponding to the two antennas used at time t2 is within a predetermined threshold (20 ms). That is, in FIG. 12B, the assumed TPC error is small.

Therefore, as shown in FIG. 13, the offset value determination unit 303 has a transmission time interval T within 20 msec, and allocation information of Format 4 (DCI format 4) (that is, data allocation information for a plurality of antenna ports). Is received, the correction value Δ _offset is set to −6 dB. Also, as shown in FIG. 13, the offset value determination unit 303 performs allocation information for Format 0 (DCI format 0) when the transmission time interval T is longer than 20 msec (that is, data allocation information for a single antenna port). ) Is received, the correction value Δ _offset is set to 0 dB. Then, the offset value determination unit 108 determines the transmission power offset value (P _{SRS_OFFSET} + Δ _offset ) by adding the correction value Δ _offset to the offset value P _{SRS_OFFSET} instructed from the base station 200.

That is, the transmission power control unit 109 receives the control information including data allocation information for a plurality of antenna ports (when the format type is format 電力 4), so that the transmission power of the A-SRS is reduced. To control the transmission power. Thereby, it is possible to set the transmission power of the uplink signal low to the minimum necessary transmission power at which the base station 400 can obtain a desired reception SINR (a reception SINR that does not deteriorate the SINR measurement accuracy). Therefore, it is possible to suppress the power consumption at terminal 300 to the minimum necessary while ensuring the SIRS measurement accuracy (channel quality accuracy) of SRS at base station 400. Further, terminal 300 can reduce inter-cell interference by suppressing the transmission power of SRS to the minimum necessary.

In addition, when receiving control information including data allocation information for one antenna port (when the format type is format 0), the transmission power control unit 109 increases the A-SRS transmission power so that the transmission power of the A-SRS increases. To control the transmission power. Thereby, it is possible to suppress an increase in the TPC error of the PA corresponding to the antenna port that was not used at the previous transmission.

Similarly to the offset setting unit 106 of the terminal 300, the offset setting unit 402 of the base station 400 is a data allocation information indicating the uplink signal transmission time interval for each terminal 300 and the PUSCH signal allocation for each terminal 300. The transmission power offset correction value _Δoffset is set based on the format type of PDCCH (including the number of antenna ports).

Here, an example of operation using Format 0 (DCI format 0) (closed-loop MIMO control processing by Fallback using Format 0) will be described.

For example, the base station 400 needs to know the propagation environment between the terminal 300 and the base station 400 because it needs to perform precoding when transmitting a PUSCH signal using a plurality of antenna ports. On the other hand, as shown in FIG. 14, when the terminal 300 does not allocate the A-SRS or PUSCH signal for a long time (the elapsed time from time t0 to time t1 in FIG. 14), the base station 400 And the base station 400 cannot grasp the propagation environment, and it becomes difficult to apply precoding by closed-loop control. Specifically, when the propagation environment is not known, base station 400 cannot specify which of a plurality of precoding examples provided in advance can increase SINR in the current propagation environment. . Moreover, if precoding is applied in a state where the propagation environment is not known in base station 400, there is a concern that the directivity generated by the precoding may decrease SINR.

Therefore, as shown in FIG. 14, when the terminal 300 does not allocate an A-SRS or PUSCH signal for a long time (for example, at time t1 shown in FIG. 14), the terminal 300 first loses data loss. In order to minimize this, a PUSCH signal is transmitted through one antenna port based on Format 0 (DCI format 0). In addition, terminal 300 transmits SRS (A-SRS) through a plurality of antenna ports in order to transmit PUSCH signals through a plurality of antenna ports after the next time.

That is, when the terminal 300 does not allocate the PUSCH for a long time, the base station 400 allocates the PUSCH so that the PUSCH signal is transmitted through one antenna port at time t1, as shown in FIG. In addition, a PDCCH (Format 0) serving as a trigger for the A-SRS transmitted at time t2 is generated. Thereby, terminal 300 can transmit A-SRS from a plurality of antenna ports at time t2 while minimizing waste associated with transmission of the PUSCH signal at time t1.

Therefore, in terminal 300, for example, at time t3 after time t2 in FIG. 14, PUSCH signal transmission using a plurality of antenna ports using an appropriate precoding matrix (that is, PUSCH in Format 4 by base station 400) Signal allocation). Therefore, in the present embodiment, even in the situation shown in FIG. 14, the terminal 300 appropriately controls and controls the transmission power of the A-SRS, so that the base station 400 can perform SINR measurement with suppressed accuracy degradation due to the TPC error. By using the value, it is possible to allocate a PUSCH signal that supports a plurality of antenna ports to the terminal 300.

Thus, in this embodiment, terminal 300 transmits transmission conditions (here, transmission time interval T and PUSCH) between the PUSCH signal transmitted last time at terminal 300 and the A-SRS transmitted this time. The transmission power offset value of A-SRS is set according to the data allocation information format used for signal allocation. Thereby, terminal 300 can specify the transmission time interval of the uplink signal at each antenna according to the format of the data allocation information. Therefore, according to this embodiment, even when different numbers of antenna ports are set for transmission of each uplink signal, as in Embodiment 1, it is possible to prevent deterioration in SINR measurement accuracy due to TPC errors in the base station. it can.

Further, in the present embodiment, for example, when the correspondence between the elapsed time T and the format of the data allocation information included in the PDCCH and the correction value Δ _offset shown in FIG. Signaling for each transmission for control becomes unnecessary. Or, in the case of notifying in advance from the base station and the format of data allocation information included in the elapsed time T and the PDCCH 13, the correspondence between the correction value delta _offset as a parameter to the terminal, the parameter is relatively long It is only necessary to notify the terminal of the period or once, and signaling for each transmission for uplink signal transmission power control becomes unnecessary. Therefore, in these cases, an increase in signaling overhead required for uplink signal transmission power control can be suppressed.

In the present embodiment, the case has been described where two types of control information (Format 0 and Format 4) related to PUSCH allocation (that is, uplink allocation) are used as control information assumed by the terminal. However, the control information assumed by the terminal is not limited thereto, and for example, control information (for example, Format 1A) related to allocation of a downlink data signal (PDSCH: Physical-Downlink-Shared-CHannel) may be used. That is, control information related to PDSCH allocation may be used as a trigger for A-SRS. In this case, the terminal may determine that there is no antenna port (number of antenna ports = 0) used for PUSCH transmission (transmission at time t1), and calculate the magnitude relationship of the number of antenna ports.

(Embodiment 3)
In this embodiment, a case will be described in which transmission power control is performed in consideration of the amount of change in transmission power in addition to the processing of Embodiment 1 or Embodiment 2.

As described above, since the transmission power is proportional to the frequency bandwidth of the transmission signal, the frequency position and bandwidth of the transmission signal change greatly as the transmission power change amount increases. That is, the amount of change in the frequency bandwidth (transmission bandwidth) of the transmission signal can be regarded as the amount of change in transmission power.

Therefore, in this embodiment, in addition to the processing of Embodiment 1 or Embodiment 2, the terminal further determines the transmission bandwidth of the signal transmitted last time and the transmission bandwidth of the signal transmitted this time. The transmission power offset value applied to the uplink signal transmitted this time is set.

In the present embodiment, as in the second embodiment, a case where a PUSCH signal is transmitted at time t1 and an A-SRS is transmitted at time t2 after time t1 will be described. However, in the present embodiment, the signals transmitted at time t1 and time t2 are not limited to the PUSCH signal and the A-SRS.

FIG. 15 shows the configuration of terminal 500 according to the present embodiment. In FIG. 15, the same components as those of the second embodiment (FIG. 10) are denoted by the same reference numerals, and the description thereof is omitted.

In terminal 500 shown in FIG. 15, allocated band information acquisition section 501 manages control information related to an allocated band of an uplink signal transmitted from terminal 500. For example, the allocated band information acquisition unit 501 acquires control information (allocated band information) related to allocation of PUSCH signals (previously transmitted signals) included in the PDCCH, and also receives A-SRS (separately notified from the base station). The allocated bandwidth information included in the information regarding the signal transmitted this time) is acquired. Further, allocated bandwidth information obtaining unit 501, a transmission bandwidth B _PUSCH of PUSCH signal (signal was last transmitted), A-SRS Ratio .DELTA.B (= B the transmission bandwidth B _SRS in (current signal to be transmitted) _SRS / B _PUSCH ) and outputs the calculated ratio to the offset value determination unit 502 of the offset setting unit 106.

The offset value determination unit 502 of the offset setting unit 106 transmits a transmission time interval between the uplink signal (PUSCH signal) transmitted immediately before (previous transmission) by the terminal 500 and the uplink signal (A-SRS) transmitted this time, A correction value for the transmission power offset value is set according to the size relationship of the number of antenna ports and the ratio of the transmission bandwidth.

Next, FIG. 16 shows the configuration of base station 600 according to the present embodiment. In FIG. 16, the same components as those in the second embodiment (FIG. 11) are denoted by the same reference numerals, and the description thereof is omitted.

In the base station 600 shown in FIG. 16, the SRS control information generation unit 601 sets P-SRS and A-SRS transmission bands to be assigned to each terminal 500, and generates SRS control information indicating the set transmission bands. Then, the SRS control information generation unit 601 notifies the generated SRS control information to each terminal 500 (not shown) and outputs it to the offset setting unit 602.

The offset setting unit 602 performs the same processing as the offset setting unit 106 of the terminal 500. That is, the offset setting unit 602 is the elapsed time from the transmission time of the PUSCH signal transmitted immediately before (previous transmission) from the terminal 500 (desired terminal), the format of the data allocation information (PDCCH) used for the allocation of the PUSCH signal. A transmission power offset value for the A-SRS is determined according to the type and the SRS control information input from the SRS control information generation unit 601.

The data SINR deriving unit 209 derives the data SINR measurement value according to the equation (8) using the A-SRS SINR measurement value and the transmission power offset value, as in the second embodiment. Then, base station 600 performs scheduling (for example, frequency resource allocation and MCS selection) of terminal 500 using the data SINR measurement value derived by data SINR deriving section 209.

Next, details of transmission power offset value setting processing in offset setting section 106 (FIG. 15) of terminal 500 and offset setting section 602 (FIG. 16) of base station 600 will be described.

In FIG. 17, it is assumed that the elapsed time (transmission time interval) T from time t1 to time t2 is within 20 ms (T ≦ 20 ms). In FIG. 17, PDCCH including control information related to PUSCH signal allocation is transmitted in Format 0 (DCI format 0). That is, in FIG. 17, one antenna port (Port 10) is set for transmission of the PUSCH signal at time t1. In FIG. 17, two antenna ports (Ports 20 and 21) are set for A-SRS transmission. Further, in FIG. 17, the transmission bandwidth B _PUSCH of PUSCH signal, the ratio _{_{ΔB (= B SRS / B PUSCH}} ) of the transmission bandwidth B _SRS of A-SRS = a 3 dB (2 times).

Therefore, the allocated bandwidth information acquisition unit 501 of the terminal 500 outputs the transmission bandwidth ratio ΔB (= B _SRS / B _PUSCH ) = 2 to the offset value determination unit 502 of the offset setting unit 106 in FIG.

First, as in Embodiment 2, the offset value determination unit 502 refers to, for example, FIG. 13 based on the transmission time interval T calculated by the calculation unit 302 and the PDCCH format type (the size relationship of the number of antenna ports). Then, a correction value is determined. For example, in FIG. 17, the offset value determination unit 502 sets the correction value to 0 dB according to FIG. 13 because the format type of PDCCH is Format （0 (DCI format 0).

Next, based on the transmission bandwidth ratio ΔB input from the allocated bandwidth information acquisition unit 501, the offset value determination unit 502 offsets the set correction value with reference to FIG. (Additional offset) is added. For example, in FIG. 17, the offset value determination unit 502 sets the additional offset amount to +2 dB according to FIG. 18 because the ratio ΔB = 3 dB. Then, the offset value determination unit 502 adds the additional offset amount (+2 dB) to the correction value (0 dB) to determine the correction value Δ _offset (that is, (0 + 2) [dB]).

In the present embodiment, for example, the SRS transmission power P _SRS (i) in sub-frame #i is obtained according to equation (5) as in the second embodiment.

As described above, when the transmission bandwidth ratio ΔB is small, the amount of change in transmission power (ΔP) is also small, so the assumed TPC error is small. On the other hand, when the transmission bandwidth ratio ΔB is large, the amount of transmission power change (ΔP) is also large, so that the assumed TPC error is large.

Therefore, as shown in FIG. 18, when the transmission bandwidth ratio ΔB is large (when the transmission power change amount ΔP is large), the offset value determination unit 502 has a small transmission bandwidth ratio ΔB (transmission power). Compared to the case where the change amount ΔP is small, the correction value Δ _offset (that is, the transmission power offset value) is increased to increase the transmission power of the A-SRS.

That is, terminal 500 sets the transmission power of A-SRS that can be regarded as having a large TPC error due to the amount of change in transmission power. As a result, it is possible to prevent the reception SINR of the A-SRS at the base station 600 from becoming a degradation region (for example, 0 dB or less) due to the influence of the TPC error, and to reduce the SINR measurement accuracy (channel quality measurement accuracy). Can be prevented.

As described above, terminal 500 uses transmission conditions (transmission time interval T and the format of data allocation information used for PUSCH signal allocation in the first or second embodiment (relationship between the number of antenna ports). In addition to)), the transmission power offset value of A-SRS is set according to the ratio of the transmission bandwidth between the PUSCH signal and A-SRS. Thereby, terminal 500 can reduce the influence of the TPC error that occurs depending on the transmission power change amount. Therefore, according to the present embodiment, even when different numbers of antenna ports are set for transmission of each uplink signal, in addition to the first and second embodiments, the TPC in the base station is considered in the frequency domain. Degradation of SINR measurement accuracy due to errors can be prevented.

Further, in this embodiment, for example, when the correspondence between the allocated bandwidth (transmission bandwidth), the allowable TPC error, and the additional offset amount shown in FIG. Signaling for each transmission becomes unnecessary. Alternatively, in the case where the association between the allocated bandwidth (transmission bandwidth), the allowable TPC error, and the additional offset amount shown in FIG. The terminal only needs to be notified once, and signaling for each transmission for uplink signal transmission power control becomes unnecessary. Therefore, in these cases, an increase in signaling overhead required for uplink signal transmission power control can be suppressed.

The embodiments of the present invention have been described above.

In the above embodiment, the case where the terminal uses a maximum of two antenna ports has been described. However, the number of antenna ports used by the terminal is not limited to this, and for example, a maximum of four antenna ports may be used.

In addition, the antenna port in the above embodiment refers to a logical antenna composed of one or a plurality of physical antennas. That is, the antenna port does not necessarily indicate one physical antenna, but may indicate an array antenna composed of a plurality of antennas.

For example, in LTE, it is not defined how many physical antennas an antenna port is composed of, but is defined as a minimum unit in which a base station can transmit different reference signals (Reference signals).

Also, the antenna port may be defined as a minimum unit for multiplying the weight of a precoding vector (Precoding vector).

Note that although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be implemented by software in association with hardware.

Further, each functional block used in the description of the above embodiment is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Although referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of progress in semiconductor technology or other derived technology, it is naturally possible to integrate functional blocks using this technology. Biotechnology can be applied.

The disclosure of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2011-001834 filed on Jan. 7, 2011 is incorporated herein by reference.

The present invention can be applied to a mobile communication system or the like.

100, 300, 500

Terminal

200, 400, 600 Base station 101 Transmission processing unit 102 Generation unit 103 Mapping unit 104 IFFT unit 105

CP addition unit

106, 207, 402, 602 Offset setting

unit

107, 302

Calculation unit

108, 303, 502 Offset value determination unit 109 Transmission power control unit 110 Precoding unit 111 Transmission RF unit 112, 201 Antenna 202 Reception RF unit 203 CP removal unit 204 FFT unit 205 Demapping unit 206 Cyclic shift amount setting unit 208 SRS SINR measurement unit 209 Data SINR derivation unit 210 PUCCH resource detection unit 211 PUCCH demodulation unit 212 PUSCH demodulation unit 213 PUSCH decoding unit 301 PDCCH detection unit 401 PDCCH generation unit 501 allocation band information acquisition unit 601 SRS control information generation unit

Claims

A control unit for controlling the transmission power of the signal;
A transmitter for transmitting the signal via at least one antenna port with the controlled transmission power;
Have
The control unit controls the transmission power based on a comparison between the number of the at least one antenna port and the number of antenna ports used for the previous transmission.
Transmitter device.
The control unit controls the transmission power to be increased when the number of the at least one antenna port is larger than the number of antenna ports used for the previous transmission.
The transmission device according to claim 1.
The control unit controls the transmission power to be small when the number of the at least one antenna port is smaller than the number of antenna ports used for the previous transmission;
The transmission device according to claim 1.
The control unit controls the transmission power to be increased when the at least one antenna port includes an antenna port that has not been used in the previous transmission.
The transmission device according to claim 1.
The control unit controls the transmission power to be small when the at least one antenna port does not include an antenna port that was not used in the previous transmission.
The transmission device according to claim 1.
The control unit controls the transmission power by increasing or decreasing an offset amount with respect to the transmission power.
The transmission device according to claim 1.
The control unit controls the transmission power based on a comparison between the number of the at least one antenna port and the number of antenna ports used for the previous transmission not more than a predetermined time interval.
The transmission device according to claim 1.
The signal is a sounding reference signal (SRS).
The transmission device according to claim 1.
The signal is a sounding reference signal (SRS) transmitted periodically or aperiodically,
The control unit is different from the SRS in the number of antenna ports used last time for transmission of a data channel, a control channel, or SRS transmitted periodically or aperiodically, and the number of the at least one antenna port. Controlling the transmission power based on the comparison with
The transmission device according to claim 1.
A control unit that controls transmission power of the sounding reference signal (SRS);
A transmission unit that receives the transmission request included in the control information and transmits the SRS through the at least one antenna port with the controlled transmission power;
Have
When receiving the control information including data allocation information for one antenna port, the control unit controls the transmission power to increase and receives the control information including data allocation information for a plurality of antenna ports. Control to reduce the transmission power,
Transmitter device.
Control the transmission power of the signal,
Transmitting the signal via at least one antenna port with the controlled transmission power;
A transmission method,
Controlling the transmission power based on a comparison between the number of the at least one antenna port and the number of antenna ports used for the previous transmission;
Transmission method.