JP5127065B2 - Wireless communication system, wireless communication method, communication device, and terminal device - Google Patents

Description

  The present invention relates to a wireless communication system, a wireless communication method, a communication device, and a terminal device.

  In wireless communication, a radio base station apparatus having a plurality of antennas performs power distribution and phase for signals transmitted from each of the plurality of antennas when propagation path characteristics from each of the plurality of antennas to the terminal apparatus are known. There is a technique for increasing the gain of a signal received by the terminal apparatus from the radio base station apparatus by adjusting the diversity effect, and maximum ratio combining (MRC) by transmission diversity (Patent Document 1).

In the next-generation mobile communication system, the radio base station apparatus needs to communicate with as many terminal apparatuses as possible in a limited frequency band. Therefore, SPC (Super Position Coding) that can multiplex and transmit data to two terminal devices with one radio resource (frequency, etc.) is promising. SPC is a method of multiplexing signals by adding a power difference to signals transmitted to two terminal apparatuses. (Non-Patent Document 1).
Here, the radio resource is a minimum unit that can transmit one modulation symbol to a terminal device, and is communication using multicarrier communication, for example, OFDM (Orthogonal Frequency Division Modulation). Indicates one subcarrier in one OFDM symbol.

In SPC, generally, a terminal device with good channel characteristics (hereinafter referred to as terminal device A) and a terminal device with poor channel characteristics (hereinafter referred to as terminal device B) simultaneously communicate with a radio base station device using the same radio resource. Technology that can. The radio base station apparatus creates a modulation symbol using a large power for a signal to be transmitted to the terminal apparatus B, and creates a modulation symbol using a small power for a signal to be transmitted to the terminal apparatus A. Add both modulation symbols and transmit.
FIG. 20 is a schematic diagram illustrating multiplexing by SPC. 20A shows a modulation symbol transmitted to the terminal apparatus B, and FIG. 20B shows a modulation symbol transmitted to the terminal apparatus A. The modulation symbol to be transmitted to the terminal apparatus B is generated with higher power than the modulation symbol to be transmitted to the terminal apparatus A, as illustrated. As an example, QPSK (Quadrature Phase Shift Keying) is used for both modulation symbols. FIG.20 (c) shows the modulation symbol which added (multiplexed) the modulation symbol of Fig.20 (a) and (b). FIG. 20D is a diagram illustrating symbols that can be taken by the added modulation symbol.

Here, if the terminal apparatus A can detect a possible value of the modulation symbol transmitted to the terminal apparatus B, the terminal apparatus A estimates the modulation symbol for the terminal apparatus B from the received signal and estimates from the received signal. By subtracting the modulation symbol for the terminal device B, the modulation symbol for the terminal device B can be detected. Also, the terminal apparatus B detects the modulation symbol for the terminal apparatus by regarding the modulation symbol transmitted to the terminal apparatus A as noise.
That is, SPC is a technique for multiplexing using the power difference between modulation symbols (signals) to be superimposed. By the above-described method, signals to two terminal apparatuses can be multiplexed and transmitted with one radio resource.
In the above description, a terminal device with good channel characteristics and a terminal device with poor channel characteristics have been described in order to simplify the operation of the SPC. Multiplexing is possible regardless of the channel characteristics.

In addition, there is a technique called multi-site SPC that multiplexes, for example, a broadcast channel or a unicast channel to a plurality of terminal devices in the same radio resource using a plurality of radio base station devices using the SPC described above. (Non-Patent Document 1).
In multi-site SPC, each of a plurality of radio base station apparatuses is synchronized, transmits a signal using the same radio resource, superimposes and combines the signals in the radio resource, and combines the terminal apparatus with a signal (synthesized). By receiving the maximum ratio combining (or equal gain combining), the effect of the maximum ratio combining by site diversity can be obtained and the communication quality can be improved.

Further, each of the plurality of radio base station apparatuses performs SPC on terminal apparatus A that communicates with the radio base station apparatus through a channel having good channel characteristics, for example, a terminal apparatus located near the radio base station apparatus by SPC. A signal to be transmitted to the terminal device A and a signal to be transmitted to another terminal device B are multiplexed and transmitted using one radio resource. At this time, the power allocated to the signal for the terminal device A is set to a smaller value than the signal transmitted to the other terminal device B.
Thereby, each radio base station apparatus can multiplex a signal in the radio resource of the broadcast channel and communicate with the terminal apparatus without adding an occupied radio resource (Non-patent Document 1).

JP-A-3-239019

“Performance of Superposition Coded Broadcast / Unicast Service Overlay System”, IEICE TRANS. COMMUN., VOL. E91-B, NO.9 SEPTEMBER 2008

In the communication using the multi-site SPC described above, a plurality of radio base station apparatuses transmit a signal addressed to a specific terminal apparatus (hereinafter referred to as a first terminal apparatus), and the specific terminal apparatus performs maximum transmission diversity. When the communication quality is improved by obtaining the effect of the ratio combining, the following problem occurs.
Since each radio base station apparatus transmits a signal with a power proportional to the received power of the first terminal apparatus for the signal transmitted from each antenna, the propagation path characteristics between the antenna and the first terminal apparatus are When it gets worse, the power of the signal received from the antenna decreases, and the transmission power from the antenna to the first terminal device is reduced. When the transmission power is lowered, the second terminal device other than the first terminal device receiving the signal multiplexed with the signal addressed to the first terminal device by the SPC is a signal for the first terminal device. The signal for the first terminal device cannot be detected using the power difference between the signal for the terminal device and the terminal device, the signal for the terminal device cannot be detected, and radio resources are effectively used by multiplexing the signals. There is a problem that it becomes impossible.

  The present invention has been made to solve the above-mentioned problem, and its purpose is in the case where the propagation path characteristic for the first terminal apparatus gaining gain by transmission diversity is deteriorated in communication using multi-site SPC. Another object of the present invention is to provide a wireless communication system that controls transmission power that allows all terminal devices other than the first terminal device to detect a signal to the first terminal device and maintain communication by multi-site SPC.

(1) In order to solve the above problem, the present invention provides a wireless communication system including a communication device that transmits different signals from a plurality of antennas, a first terminal device, and a plurality of second terminal devices. The communication apparatus receives power information received from each of the plurality of second terminal apparatuses, and generates a first modulation symbol for the first terminal apparatus based on transmission power based on the received power information. And a plurality of transmissions that multiplex the second modulation symbols for the plurality of second terminal apparatuses associated with the respective antennas and the first modulation symbols having the transmission power by superposition coding. Each of the plurality of second terminal devices is associated with one of the plurality of antennas and transmitted from the antenna. Receiving a signal, it detects the second modulation symbols from the signal received, the channel characteristic between the antenna and the own terminal device, and a received power of the first modulation symbol, the first A wireless communication system, wherein power information indicating transmission power of one modulation symbol is calculated and transmitted.

  (2) Also, in the present invention described above, the plurality of transmission processing units transmit the first modulation symbol transmitted from the plurality of antennas with a transmission power larger than a power indicated by the power information. It is characterized by that.

  (3) Further, in the present invention described above, each of the plurality of second terminal apparatuses detects the first modulation symbol for the first terminal apparatus from a signal received from the communication apparatus. The detected first modulation symbol is subtracted from the received signal to detect the second modulation symbol for the terminal device.

  (4) Further, in the present invention described above, the power indicated by the power information transmitted by each of the plurality of second terminal devices corresponds to the second terminal device and the second terminal device. The first modulation symbol can be detected by the own terminal device with respect to the transmission power of the first modulation symbol from the propagation path characteristics between the antenna and the reception power of the first modulation symbol. It is the 1st lower limit which is the transmission power of this, It is characterized by the above-mentioned.

  (5) Further, according to the present invention, in the above-described invention, each of the plurality of second terminal apparatuses estimates channel characteristics of the received signal from the received signal and calculates a channel estimation value. And the channel estimation value calculated by the channel estimation unit to calculate the first lower limit value of the transmission power of the first modulation symbol necessary for detecting the first modulation symbol A power information calculation unit, and a wireless transmission unit that transmits the first lower limit value calculated by the superimposed power information calculation unit to the communication apparatus as the power information.

  (6) Further, according to the present invention, in the above-described invention, the communication apparatus can detect the first modulation symbol according to propagation path characteristics between the first terminal apparatus and each of the plurality of antennas. A power phase calculation unit that allocates transmission power is provided.

  (7) Further, in the present invention described above, the plurality of second terminal apparatuses detect the second modulation symbol for the terminal apparatus from the channel estimation value calculated by the channel estimation unit. A superimposition power information calculation unit that calculates a second lower limit value for the transmission power of the second modulation symbol necessary for performing the second modulation symbol, wherein the radio transmission unit calculates the second power calculated by the superposition power information calculation unit The lower limit value is transmitted to the communication device, and the power phase calculation unit transmits the received transmission power of the second modulation symbol corresponding to the second terminal device that transmitted the second lower limit value. According to the value lowered to the lower limit value, the transmission power of the first modulation symbol is increased by the lowered value.

(8) Further, in the present invention described above, the communication apparatus includes two antennas as the plurality of antennas, and transmission power of a signal transmitted from the two antennas to the first terminal apparatus Is a predetermined value, and the power phase calculation unit uses the maximum ratio combining according to the propagation path characteristics between the first terminal device and each of the two antennas. When the transmission power allocated to the first modulation symbol transmitted from any one of the antennas is equal to or lower than the first lower limit value, the transmission power of the signal transmitted from the antenna is set as the first lower limit value. The remaining transmission power is allocated to the first modulation symbol transmitted from the other antenna.

(9) Further, according to the present invention, in the above invention, the communication apparatus includes two antennas as the plurality of antennas, and a sum of transmission powers of signals transmitted from the two antennas is determined in advance. The power phase calculation unit is transmitted from each of the two antennas using maximum ratio combining according to propagation path characteristics between the first terminal device and each of the two antennas. When both of the transmission powers assigned to the first modulation symbol are equal to or lower than the first lower limit value, the second lower limit value is assigned as the transmission power of the second modulation symbol, and the remaining transmissions are assigned to the first modulation symbol. It is characterized by allocating power.

(10) Further, according to the present invention, in the above-described invention, the communication apparatus includes three antennas as the plurality of antennas, and transmission power of signals transmitted from the three antennas to the first terminal apparatus The power phase calculation unit determines the transmission power for each of the three antennas using maximum ratio combining according to the propagation path characteristics between the first terminal device and each of the three antennas. When the transmission power allocated to the first modulation symbol transmitted from any one of the three antennas is less than or equal to the first lower limit value by the allocation, the first modulation transmitted from the antenna. The symbol transmission power is set as the first lower limit value, and the remaining transmission power is allocated to the first modulation symbol transmitted from another antenna. That.

(11) Moreover, this invention is a 2nd terminal device in the radio | wireless communications system which has a communication apparatus which transmits a different signal from each of several antenna, 1st terminal device, and several 2nd terminal device. From the propagation path characteristics between the antenna associated with the own terminal device among the plurality of antennas and the own terminal device, and the received power of the first modulation symbol for the first terminal device, Calculating and transmitting power information indicating the transmission power of the first modulation symbol, receiving a signal transmitted from the associated antenna, and detecting a second modulation symbol from the received signal. This is a characteristic terminal device.

  (12) Further, the present invention is a communication device in a wireless communication system having a communication device that transmits different signals from a plurality of antennas, a first terminal device, and a plurality of second terminal devices, Receiving power information received from each of the plurality of second terminal apparatuses, generating a first modulation symbol for the first terminal apparatus based on transmission power based on each of the power information, and each of the plurality of antennas; And a plurality of transmission processing units that multiplex the second modulation symbols for the plurality of second terminal devices associated with the first modulation symbol having the transmission power and the first modulation symbols by superposition coding. Is a communication device.

(13) Furthermore, the present invention provides a wireless communication system having a communication device that transmits different signals from a plurality of antennas, a first terminal device, and a plurality of second terminal devices, wherein the communication device includes: A process of receiving power information received from each of the plurality of second terminal apparatuses, generating a first modulation symbol for the first terminal apparatus by transmission power based on each of the power information, and the communication apparatus Multiplexing the second modulation symbol for the second terminal apparatus associated with each antenna and the first modulation symbol of the transmission power by superposition coding, and the plurality of second modulation symbols. Each of the terminal devices is associated with any one of the plurality of antennas, receives a signal transmitted from the antenna, and receives a previous signal from the received signal. Detecting a second modulation symbol, the propagation path characteristic between the antenna and the own terminal device, and a received power of the first modulation symbol, power information indicating transmission power of the first modulation symbol A wireless communication method comprising: calculating and transmitting.

  According to this invention, even when the propagation path characteristics between each of the plurality of antennas included in the radio base station apparatus and the first terminal apparatus deteriorate, the plurality of second terminal apparatuses are always connected to the first terminal apparatus. By detecting the modulation symbol and subtracting the modulation symbol for the first terminal device from the received signal, the modulation symbol for the own terminal device can be detected. As a result, the wireless communication system can maintain communication by multi-site superposition coding in which signals are transmitted from a plurality of antennas.

It is a schematic diagram which shows the outline of the radio | wireless communications system in 1st Embodiment. It is a figure which shows another form of the wireless base station apparatus in the embodiment. It is a figure which shows another form of the wireless base station apparatus in the embodiment. It is a schematic block diagram which shows the structure of the terminal device in the embodiment. In the embodiment, it is a figure which shows the information memorize | stored in the table part with which a to-be-superimposed power information calculation part is provided. It is a schematic block diagram which shows the structure of the data detection part in the embodiment. It is a schematic block diagram which shows the structure of the terminal device in the embodiment. It is a schematic block diagram which shows the structure of the wireless base station apparatus in the embodiment. It is a schematic block diagram which shows the structure of the modulation symbol production | generation part in the embodiment. It is a schematic block diagram which shows the structure of the transmission process part in the embodiment. It is a schematic block diagram which shows the structure of the electric power phase calculation part in the embodiment. It is a schematic diagram which shows the outline of the radio | wireless communications system in 2nd Embodiment. It is a schematic block diagram which shows the structure of the terminal device in the embodiment. It is a schematic block diagram which shows the structure of the wireless base station apparatus in the embodiment. It is a schematic block diagram which shows the structure of the transmission process part in the embodiment. It is a schematic block diagram which shows the structure of the electric power phase calculation part in the embodiment. It is a schematic diagram which shows the outline which shows the structure of the radio | wireless communications system of 3rd Embodiment. It is a schematic block diagram which shows the structure of the wireless base station apparatus in the embodiment. It is a schematic block diagram which shows the structure of an electric power phase calculation part. It is the schematic explaining the multiplexing by SPC.

  Hereinafter, a radio communication system, a radio communication method, a radio base station apparatus, and a terminal apparatus according to embodiments of the present invention will be described with reference to the drawings. Note that the wireless communication system is described as performing communication using OFDM as an example of multicarrier communication.

(First embodiment)
FIG. 1 is a schematic diagram illustrating an outline of a wireless communication system 10 according to the first embodiment. The radio communication system 10 includes a radio base station apparatus 300 that is a communication apparatus including antennas 311 and 312, a terminal apparatus 100 (first terminal apparatus), and terminal apparatuses 200 a and 200 b (second terminal apparatus). Prepare. Note that the number of first terminal devices is at least one, and the number of second terminal devices is at least two. Radio base station apparatus 300 transmits a transmission signal from a plurality of antennas 311 and 312 that are geographically separated. Further, as an example, the terminal apparatus 100 is located in an area where the cell areas of the transmission antennas 311 and 312 overlap, receives signals from the transmission antennas 311 and 312, and transmits channel state information (Channel State Information) to the radio base station apparatus 300. ; CSI). The channel state information is information indicating the state of the propagation path between the terminal device 100 and the antennas 311 and 312. The plurality of antennas 311 and 312 may be relay stations.
A communication line from the radio base station apparatus 300 to the terminal apparatuses 100, 200a, and 200b is referred to as a downlink, and a communication line from the terminal apparatuses 100, 200a, and 200b to the radio base station apparatus 300 is referred to as an uplink.

  In addition, the terminal devices 200a and 200b can detect a lower limit value of transmission power (first modulation symbol) for the terminal device 100 from a received signal multiplexed by SPC (Superposition Coding). Superposed power information (power information) indicating a lower limit value of 1) is transmitted to radio base station apparatus 300. In addition, the terminal devices 200a and 200b have the same configuration, and are hereinafter referred to as the terminal device 200 when showing either one or both. As an example, the terminal device 200 a is located in the cell area of the antenna 311, and the terminal device 200 b is located in the cell area of the antenna 312 adjacent to the cell area of the antenna 311. The terminal device 200a receives a signal transmitted from the antenna 312 with a small power that can be regarded as noise, and the terminal device 200b receives a signal transmitted from the antenna 311 with a small power that can be regarded as noise.

In FIG. 1, the two antennas 311 and 312 are described independently. However, as shown in FIG. 2, the radio base station apparatus 300 and the two antennas 311 and 312 are wired, for example, coaxial. It may be connected by a line or an optical fiber, and one radio base station apparatus 300 may transmit signals from two different places.
In addition, as in the radio communication system 11 illustrated in FIG. 3, the radio base station apparatus 300 uses radio resources with different radio resources (frequency or time) used for the terminal apparatuses 100, 200 a, and 200 b, and uses radio resources. Signals to be transmitted may be transmitted to the devices 401 and 402, and the signals may be transmitted from the radio relay station devices 401 and 402 to the terminal devices 100, 200a, and 200b. With such a configuration, one radio base station apparatus 300 can transmit radio signals from two distant locations.

In FIG. 2, the antennas 311 and 312 and the radio base station apparatus 300 are separated from each other, but one antenna may be installed at the same location as the radio base station apparatus 300 and the other may be installed at a separated location. Good. In FIG. 3, the radio relay station devices 401 and 402 and the radio base station device 300 are separated from each other, but one radio relay station device does not use the radio base station, and the radio base station device 300 and the other radio base station device 300 are separated. A signal may be transmitted from the wireless relay station device to the terminal devices 100, 200a, and 200b. In the case of the configuration illustrated in FIG. 3, a radio base station system including the radio base station device 300 and the radio relay station devices 401 and 402 can be regarded as a radio base station device.
Hereinafter, description will be given based on the configuration of FIG.

First, FIG. 4 is a schematic block diagram showing the configuration of the terminal device 200 in the same embodiment. As illustrated, the terminal device 200 includes an antenna 210, a radio reception unit 211, a GI removal unit 212, an FFT (Fast Fourier Transform) unit 213, a channel estimation unit 214, a data detection unit 215, and a replica generation unit 216. , A cancel unit 217, a data detection unit 218, a superimposed power information calculation unit 219, and a wireless transmission unit 220.
Radio receiving section 211 receives a signal transmitted from radio base station apparatus 300 via antenna 210, down-converts the received signal to a baseband frequency, and converts the down-converted signal converted to a digital signal to GI removing section 212. Output. The GI removal unit 212 removes the guard interval from the down-converted signal output from the wireless reception unit 211 and outputs it to the FFT unit 213.

The FFT unit 213 converts the down-converted signal from which the guard interval output from the GI removing unit 212 is removed, from the time domain signal to the frequency domain signal by FFT, and separates the modulation symbol of each subcarrier. The modulation symbol of each subcarrier is output to channel estimation section 214, data detection section 215, and cancellation section 217.
Here, the modulation symbol of each subcarrier output from FFT section 213 is obtained by multiplexing the modulation symbol (first modulation symbol) for terminal apparatus 100 and the modulation symbol (second modulation symbol) for terminal apparatus 200a. It is an SPC symbol, or an SPC symbol in which a modulation symbol for the terminal device 100 and a modulation symbol for the terminal device 200b are multiplexed.

Channel estimation unit 214 estimates the propagation path characteristics of each subcarrier from a known pilot signal included in each modulation symbol FFT unit 213 is output, calculates a channel estimation value h ₁ or channel estimation value h _2, The calculated channel estimation value h ₁ (h ₂ ) is output to the data detection unit 215, the replica generation unit 216, the data detection unit 218, and the superimposed power information calculation unit 219. Here, the radio base station apparatus 300 transmits known pilot signals from the antennas 311 and 312 respectively. Further, the channel estimation value h ₁ is a channel estimation value from the antenna 311 to the terminal device 200a calculated by the channel estimation unit 214 of the terminal device 200a. The channel estimate _{h 2} is the channel estimates from the antenna 312 to the channel estimation unit 214 of the terminal apparatus 200b calculates to the terminal device 200b.

The data detection unit 215 detects and detects information bits for the terminal apparatus 100 from the channel estimation value h ₁ (h ₂ ) calculated by the channel estimation unit 214 and the modulation symbol of each subcarrier input from the FFT unit 213. The information bits are output to the replica generation unit 216.
The replica generation unit 216 modulates the information bits input from the data detection unit 215, multiplies the channel estimation value h ₁ (h ₂ ) calculated by the channel estimation unit 214 by the modulated information bits, and generates the SPC symbol. A replica of the modulation symbol for the included terminal apparatus 100 is generated and output to the cancel unit 217. The cancel unit 217 subtracts the modulation symbol replica for the terminal device 100 generated by the replica generation unit 216 from the SPC symbol output by the FFT unit 213 to calculate the modulation symbol for the terminal device itself.

The data detection unit 218 detects and outputs information bits for the terminal device from the modulation symbol for the terminal device calculated by the cancellation unit 217 and the channel estimation value h ₁ (h ₂ ) calculated by the channel estimation unit 214. .
Superposed power information calculation section 219 has a lower limit (min_p ₁₁ or min_p) of transmission power in radio base station apparatus 300 for a modulation symbol obtained by modulating the information bits for which information bits for terminal apparatus 100 can be detected in the terminal apparatus. ₂₁ ) and the superimposed power information indicating the calculated lower limit value is output to the wireless transmission unit 220. Radio transmission section 220 transmits the superimposed power information output from superimposed power information calculation section 219 to radio base station apparatus 300 via antenna 210.

Next, a method for calculating the lower limit value (min_p ₁₁ or min_p ₂₁ ) of transmission power necessary for detecting information bits for the terminal device 100 by the superimposed power information calculation unit 219 will be described.
FIG. 5 is a diagram illustrating information stored in the table unit 219A included in the superimposed power information calculation unit 219 in the embodiment. The table unit 219A includes a modulation scheme (64QAM, 16QAM, QPSK, etc.), a coding method (turbo code, convolutional code, etc.), a coding rate (3/4, 1/2, 1/3, etc.) and a specific error. A [dB] value of SINR (Signal to Interference and Noise Power Ratio) that can be decoded at a rate lower than the rate is stored in association with each other. For example, when the modulation method is QPSK, the encoding method is turbo code, and the coding rate is ½, it indicates that decoding is possible if SINR = a2 [dB] or more.

The received power for the modulation symbol for the terminal apparatus 200 in the band in which the modulation symbol for the terminal apparatus 100 and the modulation symbol for the terminal apparatus 200 are multiplexed by SPC is S1 [dBm]. Is S2 [dBm], and the noise power is N [dBm]. At this time, when detecting a modulation symbol for terminal apparatus 100, SINR is expressed as S1 / (S2 + N) [dB]. Using this SINR, power S1 corresponding to the value shown in FIG. 5 is calculated. That is, the superimposed power information calculation section 219 shown in FIG. 4, for example, when the modulation scheme is QPSK, the encoding method is turbo code, and the coding rate is 1/2, the modulation scheme and coding scheme. Then, the [dB] value of SINR corresponding to the coding rate is read from the table unit 219A, and S1 = (S2 + N) * a2 is calculated. Furthermore, the superimposed power information calculation unit 219 calculates a lower limit value min_p ₁₁ (or min_p ₂₁ ) of transmission power necessary to obtain S1 (= (S2 + N) * a2).

The calculation method of the lower limit value min_p ₁₁ (or min_p ₂₁ ) of the transmission power is such that the radio base station apparatus 300 transmits in advance a pilot signal having a known power (p0) to the terminal apparatus 200 in advance, and the channel estimation of the terminal apparatus 200 The reception power S0 [dBm] of the pilot signal power received by unit 214 is measured. The superimposed power information calculation unit 219 calculates min_p ₁₁ (= S1 / S0 * p0 [dBm]) as the superimposed power information from the received power S0 [dBm] of the pilot signal.
Note that the superimposed power information calculation unit 219 takes into account the loss due to channel estimation error, time variation of the propagation path, and the loss of modulation symbols for the terminal apparatus 200 that can be regarded as an interference signal, to a constant margin in the above SINR. May be included to calculate the lower limit value min_p ₁₁ (or min_p ₂₁ ) of the transmission power.

  Next, FIG. 6 is a schematic block diagram showing the configuration of the data detection unit 215. The data detection unit 215 includes a channel compensation unit 251, a demodulation unit 252, and a decoding unit 253. The channel compensation unit 251 calculates the input modulation symbol by the channel estimation unit 214, performs channel compensation using the channel estimation value, and outputs the result to the demodulation unit 252. Demodulation section 252 demodulates the channel-compensated modulation symbol output from channel compensation section 251, and outputs the hard decision value or soft decision value for each bit obtained by demodulation to decoding section 253. Decoding section 253 decodes and outputs information bits from the hard decision value or soft decision value for each bit output from demodulation section 252. Note that the data detection unit 218 has the same configuration as the data detection unit 215, although the modulation method, coding method, coding rate, and the like in demodulation and decoding may be different.

  Next, FIG. 7 is a schematic block diagram showing the configuration of the terminal device 100 in the same embodiment. The terminal device 100 includes an antenna 110, a radio reception unit 111, a GI removal unit 112, an FFT unit 113, a channel estimation unit 114, a data detection unit 115, and a radio transmission unit 116. The radio reception unit 111 receives a signal transmitted from the antennas 311 and 312 of the radio base station apparatus 300 using the same radio resource, combined in the radio resource, and down-converts the received signal to a baseband frequency. To the GI removal unit 112. GI removal section 112 removes the guard interval from the down-converted signal output from radio reception section 111 and outputs the result to FFT section 113.

  FFT section 113 converts the time domain signal into the frequency domain signal by FFT from the downconverted signal from which the guard interval output from GI removing section 112 is removed, and separates the modulation symbol of each subcarrier to perform channel estimation. Output to the unit 114 and the data detection unit 115.

The channel estimator 114 estimates the channel estimation value h ₁ and the antenna 312 from the pilot symbols out of the modulation symbols of each subcarrier output by the FFT unit 113 by estimating the propagation path between the antenna 311 and the terminal device itself. The channel estimation value h ₂ is calculated by estimating the propagation path with the own terminal device, and the channel estimation values h ₁ and h ₂ are output to the data detection unit 115. Further, the channel estimation unit 114 calculates a power ratio (| h ₁ | ² / | h ₂ | ² ) and a phase difference (arg (h ₁ / h ₂ )) from the calculated channel estimation values h ₁ and h _2. Then, channel state information (CSI) including the calculated channel estimation values h ₁ and h ₂ calculated, power ratio information indicating the power ratio, and phase difference information indicating the calculated phase difference is transmitted to the wireless transmission unit 116. Output. Here, arg () indicates a complex argument.
Based on the channel estimation values h ₁ and h ₂ calculated by the channel estimation unit 114, the data detection unit 115 regards the modulation symbol for the terminal device 200 as noise from the modulation symbols of each subcarrier output by the FFT unit 113, Detect and output information bits for the device. The data detection unit 115 has the same configuration as the data detection unit 215 shown in FIG.

Radio transmission section 116 transmits channel state information (CSI) output from channel estimation section 114 to radio base station apparatus 300 via antenna 110.
Here, the signal received by the radio reception unit 111 is the signal transmitted from the antennas 311 and 312 of the radio base station apparatus 300 using the same radio resource, and the power phase calculation unit 320 of the radio base station apparatus 300 (FIG. 8). Is a signal (synthesized signal) superimposed by the ratio calculated by the above. Then, the terminal device 100 receives a signal obtained by combining the signals transmitted from the two geographically separated antennas 311 and 312, thereby achieving a diversity effect with the same ratio as the maximum ratio combining or a ratio close thereto. obtain.

FIG. 8 is a schematic block diagram showing the configuration of the radio base station apparatus 300 in the same embodiment. The radio base station apparatus 300 includes antennas 311 and 312, a power phase calculation unit 320, transmission processing units 330 a and 330 b, and modulation symbol generation units 340 a, 340 b, and 340 c.
Note that the transmission processing units 330a and 330b have the same configuration, and hereinafter, when one or both of them are indicated, they are referred to as the transmission processing unit 330. Also, the modulation symbol generation units 340a, 340b, and 340c have the same configuration, and hereinafter, when any one or all of them are shown, they are referred to as modulation symbol generation units 340.

The power phase calculation unit 320 is calculated according to the superimposed power information transmitted from the terminal devices 200a and 200b via the antennas 311 and 312 and the phase difference information and power ratio information transmitted from the terminal device 100. The superimposed power phase designation information is output to the transmission processing units 330a and 330b. Details of the power phase calculation unit 320 will be described later.
Here, the superimposed power information is information indicating a lower limit value of transmission power from the radio base station apparatus 300 that can detect a modulation symbol for the terminal apparatus 100 in the terminal apparatuses 200a and 200b. Here, the superimposed power phase designation information is input to the power phase control unit 331 (FIG. 10) included in the transmission processing unit 330 and includes the transmission power value of the modulation symbol for the terminal device 100 and the amount of rotation of the phase rotation. Information.

  The modulation symbol generation unit 340a receives information bits for the terminal device 200a and outputs a modulation symbol obtained by modulating the input information bits to the transmission processing unit 330a. The modulation symbol generation unit 340b receives information bits for the terminal device 200b and outputs the information bits to the modulation symbol transmission processing unit 330b that modulates the input information bits. Modulation symbol generation section 340c receives information bits for terminal apparatus 100, and outputs modulation symbols obtained by modulating the input information bits to transmission processing sections 330a and 330b. The modulation symbol generators 340a to 340c have the same configuration, and hereinafter, when any or all of the modulation symbol generators 340a to 340c are shown, they are referred to as modulation symbol generators 340.

  The transmission processing unit 330a generates a transmission signal from the modulation symbols input from the modulation symbol generation units 340a and 340c based on the superimposed power phase designation information input from the power phase calculation unit 320, and the generated transmission signal The data is transmitted to the terminal devices 100 and 200a via the antenna 311. The transmission processing unit 330b generates a transmission signal based on each of the modulation symbols input from the modulation symbol generation units 340b and 340c and the superimposed power phase designation information input from the power phase calculation unit 320, and the generated transmission signal Is transmitted to the terminal devices 100 and 200b via the antenna 312.

  FIG. 9 is a schematic block diagram showing the configuration of the modulation symbol generator 340 in the same embodiment. The modulation symbol generation unit 340 includes an encoding unit 341 and a modulation unit 342. The encoding unit 341 receives information bits to be transmitted, and forward error correction (Forward Error Correction) by using a turbo code, a convolutional code, an LDPC (Low Density Parity Check Code), or the like. Correction; FEC) is performed and output to the modulation unit 342. Modulation section 342 modulates the information bits encoded by encoding section 341 and outputs the generated modulation symbols. At this time, as the modulation performed by the modulation unit 342, for example, QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), 64QAM (64 Quadrature Amplitude Modulation; 64) Value quadrature amplitude modulation).

Next, FIG. 10 is a schematic block diagram showing the configuration of the transmission processing unit 330 in the same embodiment. The transmission processing unit 330 is referred to as a power phase control unit 331, a power control unit 332, an SPC unit 333, an IFFT (Inverse Fast Fourier Transform) unit 334, and a guard interval insertion unit 335 (hereinafter referred to as a GI insertion unit 335). ) And a wireless transmission unit 336.
The power phase control unit 331 performs power (amplitude) change and phase rotation on the modulation symbol for the input terminal device 100 based on the superimposed power phase designation information input from the power phase calculation unit 320, and performs SPC. To the unit 333. The power control unit 332 converts the input modulation symbol for the terminal device 200 into a modulation symbol having a predetermined power (amplitude) and outputs the modulation symbol to the SPC unit 333. Here, the predetermined power is power calculated based on a channel estimation value of a propagation path between the antennas 311 and 312 and the terminal device 200, power determined by a communication standard, or the like.

  SPC section 333 adds two modulation symbols input from power phase control section 331 and power control section 332 to generate an SPC symbol, and outputs the generated SPC symbol to IFFT section 334. IFFT section 334 generates a downlink signal by assigning each input SPC symbol to a subcarrier and performing inverse FFT, and outputs the generated downlink signal to GI insertion section 335. GI insertion section 335 inserts a guard interval into the downlink signal input from IFFT section 334 and outputs the result to radio transmission section 336. The radio transmission unit 336 up-converts the downlink signal in which the guard interval is inserted, converts the downlink signal into an analog transmission signal, and transmits the transmission signal to the terminal apparatus 100 and the terminal apparatus 200 via the connected antenna 311 or antenna 312. Send.

FIG. 11 is a schematic block diagram showing the configuration of the power phase calculation unit 320 in the same embodiment. The power phase calculation unit 320 includes a phase difference information detection unit 321, a power ratio information detection unit 322, a superimposed power information detection unit 323, a superimposed power information detection unit 324, and an information calculation unit 325.
The phase difference information detection unit 321 is connected to the antennas 311 and 312, detects phase difference information transmitted from the terminal device 100 from the received signal, and outputs the phase difference information to the information calculation unit 325. The power ratio information detection unit 322 is connected to the antennas 311 and 312, detects power ratio information transmitted by the terminal device 100 from the received signal, and outputs the power ratio information to the information calculation unit 325. The superimposed power information detection unit 323 is connected to the antenna 311, detects the superimposed power information transmitted by the terminal device 200 a, and outputs it to the information calculation unit 325. The superimposed power information detection unit 324 is connected to the antenna 312, detects the superimposed power information transmitted by the terminal device 200 b, and outputs it to the information calculation unit 325. The information calculation unit 325 includes phase difference information output from the phase difference information detection unit 321, power ratio information output from the power ratio information detection unit 322, and superimposed power information output from the superimposed power information detection units 323 and 324. Then, the superimposed power phase designation information for the transmission processing unit 330a and the superimposed power phase designation information for the transmission processing unit 330b are calculated and output to the transmission processing units 330a and 330b, respectively.

  Here, the phase difference information is the propagation path characteristics between the antenna 311 and the terminal apparatus 100 and the propagation path characteristics between the antenna 312 and the terminal apparatus 100 from the antenna 311 in the terminal apparatus 100. This is information representing the difference between the amount of phase rotation due to the propagation path and the amount of phase rotation due to the propagation path from the antenna 312. The power ratio information is the attenuation of signal power due to the propagation path characteristic from the antenna 311 calculated from the propagation path characteristic between the antenna 311 and the terminal apparatus 100 and the propagation path characteristic between the antenna 312 and the terminal apparatus 100. The ratio between the rate and the attenuation rate of the signal power due to the propagation path from the antenna 312. The superimposed power information is information indicating transmission power values of the modulation symbols that can detect the modulation symbols for the terminal device 100 in the terminal devices 200a and 200b.

Hereinafter, processing performed by the information calculation unit 325 will be described. Here, the power allocated to the modulation symbol for the terminal apparatus 100 transmitted from the antenna 311 is p _11, and the power allocated to the modulation symbol for the terminal apparatus 200 a is p ₁₂ . Further, the power allocated to modulation symbols for the terminal device 100 to be transmitted from the antenna 312 and _{p 21,} and the power _{p 23} to be allocated to modulation symbols for the terminal device 200b. Moreover, p1 (= p ₁₁ + p ₂₁ ) of power allocated to the modulation symbol for terminal apparatus 100 is a predetermined constant value, and is determined by, for example, the rated transmission power of radio base station apparatus 300.

Also, the terminal apparatus 100 uses the channel estimation unit 114 to estimate the channel estimation value h ₁ indicating the channel characteristic from the antenna 311 to the terminal apparatus and the channel estimation indicating the channel characteristic from the antenna 312 to the terminal apparatus. The power ratio information indicating the power ratio (| h ₁ | ² / | h ₂ | ² ) and the phase difference (arg (h ₁ / h ₂ )) from the value h ₂ and the channel estimation values h ₁ and h ₂ The phase difference information shown is calculated, and channel state information (CSI) including these pieces of information is transmitted to the radio base station apparatus 300.

The terminal device 200a transmits the object superimposed power information indicating the lower limit min_p ₁₁ of the transmission power _{p 11} of its own terminal apparatus can detect the modulation symbols for the terminal apparatus 100 to the radio base station apparatus 300. Terminals 200b, similar to the terminal device 200a, transmits the lower limit min_p ₂₁ of the transmission power _{p 21} of its own terminal apparatus can detect the modulation symbols for the terminal apparatus 100 to the radio base station apparatus 300.

  When performing communication based on Maximum Ratio Combining (MRC), in the radio base station apparatus 300, the information calculation unit 325 performs processing represented by the following equations (1-1) and (1-2). Calculate the power and phase to do.

Here, x ₁ is a modulation symbol for the terminal apparatus 100, y ₁₁ is a modulation symbol for the terminal apparatus 100 transmitted from the antenna 311, and y ₂₁ is a modulation symbol for the terminal apparatus 100 transmitted from the antenna 312. is there. _{That, y 11} represents the modulation symbols power phase control unit 331 of the transmission processing unit 330a _{outputs, y 21} represents the modulation symbols power phase control unit 331 of the transmission processing unit 330b outputs.
Hereinafter, lower limit values min_p ₁₁ , min_p ₂₁ , modulation symbol transmission amplitude P 1 for terminal apparatus 100 transmitted from antenna 311 in the case of performing communication based on maximum ratio combining, and terminal apparatus 100 transmitted from antenna 312. The operation of the information calculation unit 325 in each case will be described by classifying the cases according to the magnitude relationship with the transmission amplitude P2 of the modulation symbol. However, the transmission amplitudes P1 and P2 are as follows.
P1 = | h ₁ | / √ (| h ₁ | ² + | h ₂ | ² ) · √p ₁
P2 = | h ₂ | / √ (| h ₁ | ² + | h ₂ | ² ) · √p ₁
Here, it is assumed that the transmission amplitude of a modulation symbol is the square root of the power of the modulation symbol.

<Case 1>
The transmission amplitude of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is larger than the square root of the lower limit value of transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and the terminal device transmitted from the antenna 312. When the transmission amplitude of the modulation symbol for 100 is larger than the square root of the lower limit value of transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100, that is, P1> (min_p ₁₁ ) ^1/2 and P2> ( When min_p ₂₁ ) ^1/2 (condition 1-1) is satisfied, the information calculation unit 325 outputs the superimposed power phase designation information represented by the expression (2-1) to the transmission processing unit 330a, and the transmission processing unit The superimposed power phase designation information represented by the equation (2-1) is output to 330b.

  Under the above-described conditions, the terminal device 100 that receives signals transmitted from the antennas 311 and 312 of the radio base station device 300 can improve the communication quality by obtaining the effect of maximum ratio combining by site diversity.

<Case 2>
The transmission amplitude of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is equal to or less than the square root of the lower limit value of the transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and the terminal transmitted from the antenna 312. The transmission amplitude of the modulation symbol for the device 100 is larger than the square root of the lower limit value of the transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100, and the total transmission power of the modulation symbol for the terminal device 100 is the terminal device 200a. Is equal to or greater than the sum of the lower limit value of transmission power capable of detecting the modulation symbol for the terminal device 100 and the lower limit value of transmission power capable of detecting the modulation symbol for the terminal device 100, that is, P1 ≦ (min_p ₁₁ ) ^1/2 and P2> (min_ When p ₂₁ ) ^1/2 and p1 ≧ min_p ₁₁ + min_p ₂₁ (Condition 1-2) are satisfied, the information calculation unit 325 transmits the modulation symbol addressed to the terminal device 100 to the following equations (3-1) and (3- In order to obtain y ₁₁ and y ₂₁ represented by 2), the superimposed power phase designation information represented by Expression (3-3) is output to the transmission processing section 330a, and Expression (3- The superposed power phase designation information represented by 4) is output.

The power phase control unit 331 in the transmission processing units 330a and 330b responds to the propagation path between the antenna 311 and the terminal device 100 whose propagation path state is not good according to the superimposed power phase information input from the information calculation unit 325. Then, a lower limit value min_p ₁₁ of transmission power equal to or higher than transmission power P1 is assigned. As a result, the terminal device 100 cannot obtain the transmission diversity effect as high as the maximum ratio combining, but can obtain the transmission diversity effect exceeding the equal gain combining, and the terminal device 200a is self-terminal multiplexed by SPC. Detection of modulation symbols for the device can be performed.

<Case 3>
The transmission amplitude of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is larger than the square root of the lower limit value of transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and the terminal device transmitted from the antenna 312. 100 is equal to or less than the square root of the lower limit value of the transmission power at which the terminal apparatus 200b can detect the modulation symbol for the terminal apparatus 100, and the total transmission power of the modulation symbols for the terminal apparatus 100 is equal to the terminal apparatus 200a. Is equal to or greater than the sum of the lower limit value of the transmission power at which the modulation symbol for the terminal apparatus 100 can be detected and the lower limit value of transmission power at which the terminal apparatus 200b can detect the modulation symbol for the terminal apparatus 100, that is, P1> (min_p ₁₁ ) ^1/2 and P2 ≦ (min_ When p ₂₁ ) ^1/2 and p1 ≧ min_p ₁₁ + min_p ₂₁ (Condition 1-3) are satisfied, the information calculation unit 325 outputs the signal y represented by the following equations (4-1) and (4-2). ₁₁ and y ₂₁ are transmitted so that the superimposed power phase designation information represented by the equation (4-3) is output to the transmission processing unit 330a, and the transmission processing unit 330b is represented by the equation (4-4). Output superimposed power phase designation information.

  Similarly to the case 2 described above, the power phase control unit 331 in the transmission processing units 330a and 330b includes an antenna 312 and a terminal whose propagation path state is not good according to the superimposed power phase information input from the information calculation unit 325. A transmission power min_p <b> 21 having a transmission amplitude P <b> 2 or more is assigned to the propagation path with the apparatus 100. As a result, the terminal device 100 cannot obtain the transmission diversity effect as high as the maximum ratio combining, but can obtain the transmission diversity effect exceeding the equal gain combining, and the terminal device 200b is self-terminal multiplexed by SPC. Detection of modulation symbols for the device can be performed.

<Case 4>
The total transmission power of modulation symbols for terminal apparatus 100 is a lower limit value of transmission power at which terminal apparatus 200a can detect a modulation symbol for terminal apparatus 100, and a lower limit value of transmission power at which terminal apparatus 200b can detect a modulation symbol for terminal apparatus 100. In other words, when p1 <min_p ₁₁ + min_p ₂₁ (Condition 1-4) is satisfied, the transmission rate of the modulation symbol to be transmitted to the terminal apparatus 100 is lowered, or the radio base station apparatus 300 transmits The transmission power of the entire signal is increased, and processing that satisfies p1 ≧ min_p ₁₁ + min_p ₂₁ is performed. Thereby, the terminal device 100 can obtain the transmission diversity effect of maximum ratio combining, and the terminal device 200b can detect the modulation symbol for the terminal device multiplexed by SPC.

  As described above, in the downlink of the radio communication system 10, the terminal device 200 transmits the lower limit value of the transmission power at which the modulation symbol for the terminal device 100 can be detected to the radio base station device 300, whereby the radio base station device 300. However, when the power for the modulation symbol for the terminal apparatus 100 is calculated based on the maximum ratio combining, it is determined whether or not the power value transmitted by the terminal apparatus 200 is smaller. When the power of the modulation symbol for the terminal apparatus 100 is smaller than the power value transmitted by the terminal apparatus 200, the radio base station apparatus 300 performs transmission that provides a diversity effect close to maximum ratio combining to the terminal apparatus 100, and The terminal apparatus 200 can transmit a signal with power that can detect a modulation symbol for the terminal apparatus 100. At this time, terminal apparatus 200 can detect the modulation symbol for the terminal apparatus by subtracting the modulation symbol for terminal apparatus 100 from the received signal multiplexed by SPC, and can decode the information bits from the modulation symbol. .

In the present embodiment, the terminal apparatus 100 calculates the power ratio (| h ₁ | ² / | h ₂ | ² ) and the phase difference (arg (h ₁ / h ₂ )), and the radio base station apparatus 300. However, instead of the power ratio and the phase difference, the radio base station apparatus 300 estimates the propagation path from the terminal apparatus 100 to the antennas 311 and 312 and calculates the channel estimation values h ₁ and h _2. Thus, the power ratio and the phase difference may be calculated using the reversibility of the propagation path. Also, information indicating complex channel estimation values h ₁ and h ₂ may be used, or information including other power ratio information and phase difference information may be used.

(Second Embodiment)
FIG. 12 is a schematic diagram showing an outline of the wireless communication system 20 in the second embodiment. The radio communication system 20 includes a radio base station apparatus 301 including antennas 311 and 312, a terminal apparatus 100 (first terminal apparatus), and terminal apparatuses 201 a and 201 b (second terminal apparatus). Also, the terminal device 100 receives signals from the transmission antennas 311 and 312 and transmits a channel estimation value to the radio base station device 301 as channel state information (CSI).
Moreover, the terminal device 100 is the same structure as the terminal device 100 of 1st Embodiment, attaches | subjects the same code | symbol and abbreviate | omits the description. The terminal devices 201a and 201b have the same configuration, and are hereinafter referred to as the terminal device 201 when showing either one or both.

Also, the terminal apparatuses 201a and 201b receive the lower limit value (first lower limit value) of transmission power that can detect the modulation symbol (first modulation symbol) for the terminal apparatus 100 from the received signal multiplexed by SPC. The superimposition power information and the superimposition power information indicating the lower limit value (second lower limit value) of transmission power capable of detecting the modulation symbols (second modulation symbols) for the terminal apparatuses 201a and 201b are transmitted to the radio base station apparatus 300. .
Here, the method by which the superimposed power information calculation unit 221 calculates the second lower limit value is the same as the calculation method of the lower limit value min_p11 (or min_p21) of the transmission power calculated by the superimposed power information calculation unit 219 in the first embodiment. The pilot signal having the same power (p0) transmitted by the radio base station apparatus 301 is received, and is calculated using the received power S0 [dBm] of the received pilot signal.

  Next, FIG. 13 is a schematic block diagram showing the configuration of the terminal device 201 in the same embodiment. As illustrated, the terminal device 201 includes an antenna 210, a radio reception unit 211, a GI removal unit 212, an FFT unit 213, a channel estimation unit 214, a data detection unit 215, a replica generation unit 216, a cancellation unit 217, and a data detection unit 218. , A superimposed power information calculation unit 219, a superimposed power information calculation unit 221, and a wireless transmission unit 222. Also, the terminal device 201 is different from the terminal device 200 of the first embodiment in the superimposed power information calculation unit 221 and the wireless transmission unit 222, and the same reference numerals (210 to 210) are used in the same configuration as the first embodiment. 219) and the description thereof is omitted.

Superimposition power information calculation section 221 calculates and calculates a lower limit value (min_p ₁₂ , min_p ₂₃ ) of transmission power in radio base station apparatus 301 of the modulation symbol for which the information bit for the terminal apparatus can be detected in the terminal apparatus. The lower limit value is output to the wireless transmission unit 220 as superimposed power information. The radio transmission unit 222 transmits the superimposed power information output from the superimposed power information calculation unit 219 and the superimposed power information calculated by the superimposed power information calculation unit 221 to the radio base station apparatus 301.
Here, the superimposed power information (min_p ₁₂ ) indicates a lower limit value of transmission power with which the terminal device 201a can detect a modulation symbol for the terminal device 201a included in the received signal received from the antenna 311. Also, the superimposed power information (min_p ₂₃ ) indicates a lower limit value of transmission power at which the terminal device 201b can detect a modulation symbol for the terminal device 201b included in the received signal received from the antenna 312.

  Next, FIG. 14 is a schematic block diagram showing the configuration of the radio base station apparatus 301 in the same embodiment. The radio base station apparatus 301 includes antennas 311 and 312, a power phase calculation unit 350, transmission processing units 360a and 360b, and modulation symbol generation units 340a, 340b, and 340c. Note that the transmission processing units 360a and 360b have the same configuration, and are hereinafter referred to as a transmission processing unit 360 when one or both of them are indicated.

The power phase calculation unit 350 calculates the superposed power information and superposed power information transmitted by the terminal devices 201a and 201b via the antennas 311 and 312 and the phase difference information and power ratio information transmitted by the terminal device 100. The superimposed power phase designation information is output to the transmission processing units 360a and 360b.
The modulation symbol generators 340a to 340c have the same configuration as the modulation symbol generator 340 of the first embodiment shown in FIG.

FIG. 15 is a schematic block diagram showing the configuration of the transmission processing unit 360 in the same embodiment. The transmission processing unit 360 includes a power phase control unit 331, a power control unit 361, an SPC unit 333, an IFFT unit 334, a GI insertion unit 335, and a wireless transmission unit 336, and is compared with the transmission processing unit 330 of the first embodiment. Only the power control unit 361 is different. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals (331, 333 to 336), and description thereof is omitted.
The power control unit 361 performs control to change the transmission power of the input modulation symbol for the terminal device 201 according to the superimposed power designation information calculated by the power phase calculation unit 350, and sends the modulation symbol subjected to power control to the SPC unit 333. Output. Here, the superimposed power designation information is information for setting the power of the modulation symbol for the terminal apparatus 201.

  FIG. 16 is a schematic block diagram showing the configuration of the power phase calculation unit 350 in the same embodiment. The power phase calculation unit 350 includes a phase difference information detection unit 321, a power ratio information detection unit 322, superimposed power information detection units 323 and 324, and superimposed power information detection units 351 and 352, and the power phase calculation according to the first embodiment. Compared with the unit 320, the superimposed power information detection units 351 and 352 and the information calculation unit 353 are different, and the same reference numerals (321 to 324) as those of the first embodiment are given to other configurations, and the description thereof is omitted.

The superimposed power information detection unit 351 is connected to the antenna 311, detects the superimposed power information (min_p ₁₂ ) transmitted by the terminal device 201 a, and outputs it to the information calculation unit 353. The superimposed power information detection unit 352 is connected to the antenna 312, detects the superimposed power information (min_p ₂₃ ) transmitted by the terminal device 201 b, and outputs it to the information calculation unit 353.
The information calculation unit 353 includes phase difference information output from the phase difference information detection unit 321, power ratio information output from the power ratio information detection unit 322, and superimposed power output from the superimposed power information detection units 323 and 324. From the information and the superimposed power information output by each of the superimposed power information detection units 351 and 352, the superimposed power phase designation information and the superimposed power designation information for the transmission processing unit 360a, and the superimposed power phase designation information for the transmission processing unit 360b And the superimposed power designation information are output to the transmission processing units 360a and 360b, respectively.

Hereinafter, the calculation operation performed by the information calculation unit 353 will be described. Here, the total power p (= p ₁₁ + p ₂₁ + p ₁₂ + p ₂₃ ) for signals transmitted to the terminal devices 100, 201 a, 201 b is constant, and is determined by, for example, the rated transmission power of the radio base station device 301. It is done.
When performing communication based on normal maximum ratio combining (MRC), the information calculation unit 353 calculates the power and phase for performing the processing represented by the equations (1-1) and (1-2). . Here, as in the first embodiment, a description will be given for each case.

  The operation of the information calculation unit 353, that is, the superimposed power phase designation information output to each of the transmission processing units 360a and 360b is the same as the information calculation unit 325 of the first embodiment in case 1 to case 3. At this time, the information calculation unit 353 generates a predetermined power value for the superimposed power designation information for designating the power of the modulation symbol for the terminal apparatus 201a and the superimposed power designation information for designating the power of the modulation symbol for the terminal apparatus 201b. The information shown is output. Here, the predetermined power is power calculated based on a channel estimation value of a propagation path between the antennas 311 and 312 and the terminal device 200, power determined by a communication standard, or the like.

Here, the SINR when the terminal device 201a detects a modulation symbol for the terminal device 100 is | h ₁₂ | ² · p ₁₁ / (p ₁₂ + n2). Here, the channel estimation value h ₁₂ is the channel estimation value of the propagation path from the antenna 311 to the terminal device 201a, p ₁₂ is the transmission power of the modulation symbol for the terminal device 201a in the transmission antenna 311, and n2 is Noise power. In the above _SINR, by replacing _{p 12} to min_p _12, results in lowering the transmission power to be allocated to modulation symbols for the terminal device 201a, it is possible to use the difference between the transmission power as a power to be allocated to modulation symbols for the terminal apparatus 100.
Similarly, the SINR when detecting a modulation symbol for the terminal device 201b is | h ₂₃ | ² · p ₂₁ / (p ₂₃ + n3). Channel estimate _{h 23} is the channel estimation value of the propagation path from the antenna 312 to the terminal _{201b, p 23} is the transmit power of modulation symbols for the terminal apparatus 201 in the transmitting antenna 312, n3 is the noise power is there. In the above _SINR, by replacing _{p 23} to min_p ₂₃ results in lowering the transmission power to be allocated to modulation symbols for the terminal device 201b, a difference between transmission power, further, be used to power allocated to modulation symbols for the terminal device 100 Can do. At this time, the transmission power of the modulation symbol for the terminal device 100 is referred to as an allocatable upper limit power, and is represented by a total value p′1 of the two transmission antennas 311 and 312.
p ′ ₁ = p ₁ + (p ₁₂ −min_p ₂₁ ) + (p ₂₃ −min_p ₂₃ )

Hereinafter, the operation of the information calculation unit 325 will be described by dividing case 4 of the first embodiment into case 4-1 and case 4-2.
<Case 4-1>
The allocable upper limit power is not less than the sum of the lower limit value of transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100 and the lower limit value of transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100. That is, when p ′ ₁ ≧ min_p ₂₁ + min_p ₁₁ (Condition 1-4-1) is satisfied, the information calculation unit 353 causes the transmission processing unit 360a to include the superimposed power phase represented by the following equation (5-1). The designation information is output, and the superimposed power phase designation information represented by Expression (5-2) is output to the transmission processing unit 360b. Also, the information calculation unit 353 outputs min_p ₁₂ to the transmission processing unit 360a as superimposed power designation information, and outputs min_p ₂₃ to the transmission processing unit 360b as superimposed power designation information.

<Case 4-2>
The assignable upper limit power is smaller than the sum of the lower limit value of transmission power at which the terminal device 200a can detect a modulation symbol for the terminal device 100 and the lower limit value of transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100. That is, when p ′ ₁ <min_p ₂₁ + min_p ₁₁ (Condition 1-4-2) is satisfied, the transmission rate of the modulation symbol transmitted to the terminal apparatus 100 is lowered, or the entire signal transmitted by the radio base station apparatus 301 The transmission power is increased, and processing that satisfies p ₁ ≧ min_p ₁₁ + min_p ₂₁ is performed.

As described above, the radio base station apparatus 301 receives the superimposed power information (min_p ₁₂ ) received from the terminal apparatus 201a and the superimposed power information (min_p ₂₃ ) received from the terminal apparatus 201b. When the radio base station apparatus 301 has insufficient transmission power for the terminal apparatus 100 and the terminal apparatuses 201a and 201b cannot detect modulation symbols for the terminal apparatus 100, the radio base station apparatus 301 superimposes power allocated to the modulation symbols for the terminal apparatuses 201a and 201b, respectively. The power is reduced to the power indicated in the power information, and the difference is assigned to the modulation symbol for the terminal device 100. Thereby, even when the radio base station apparatus 301 cannot cope with the change of power allocation in the first embodiment in the downlink (case 4), the same radio resource is provided to the three terminal apparatuses 100, 201a, and 201b. Thus, information bits can be multiplexed and transmitted.

(Third embodiment)
FIG. 17 is a schematic diagram illustrating an outline of the configuration of the wireless communication system 30 according to the third embodiment. Further, as illustrated, as an example, the terminal device 200a is located in the cell area of the antenna 311 and the terminal device 200b is located in the cell area of the antenna 312 adjacent to the cell area of the antenna 311. 200c is located in the cell area of the antenna 313 adjacent to the cell areas of the antennas 311 and 312, and the terminal device 100 is located at the end of the above-described three cell areas. The radio communication system 30 includes a radio base station apparatus 303 including antennas 311 to 313, a terminal apparatus 100 (first terminal apparatus), and terminal apparatuses 200a to 200c (second terminal apparatus). In addition, the wireless communication system 30 extends the wireless communication system 10 of the first embodiment, adds an antenna 313 and a terminal device 200c having the same configuration as the terminal devices 200a and 200b, and is a terminal on which multiplexing by SPC is performed. In this configuration, there are three devices.
The radio base station apparatus 303 transmits a transmission signal from a plurality of antennas 311, 312, and 313 that are geographically separated. Further, the terminal device 100 receives signals from the transmission antennas 311 to 313 and transmits channel state information (CSI) to the radio base station device 303. Also, the terminal devices 200a to 200c each have a transmission power lower limit value (first lower limit value) that can detect a modulation symbol (first modulation symbol) for the terminal device 100 from a received signal multiplexed by SPC. The superimposed power information is transmitted to the radio base station apparatus 303.

The terminal device 100 has the same configuration as that of the terminal device 100 of the first embodiment illustrated in FIG. 7, but the processing of the channel estimation unit 114 is different due to the provision of the antenna 313.
The channel estimation unit 114 calculates a channel estimation value h ₃ indicating the propagation path characteristic between the antenna 313 and the terminal apparatus, and a channel estimation value h ₂ indicating the propagation path characteristic between the antenna 312 and the terminal apparatus. Channel state information (CSI) including a power ratio (| h ₃ | ² / | h ₂ | ² ) and a phase difference (arg (h ₃ / h ₂ )) between the channel estimation value h ₃ and the radio base station To the device 303. Note that the terminal apparatus 100 may calculate using the known signal transmitted from the terminal apparatus 100 without transmitting the above power ratio and phase difference to the wireless base station apparatus 303.
The terminal devices 200a to 200c have the same configuration as the terminal device 200 of the first embodiment shown in FIG. 4, and are denoted by the same reference numerals (200) and description thereof is omitted.

  Next, FIG. 18 is a schematic block diagram showing the configuration of the radio base station apparatus 303 in the same embodiment. The radio base station device 303 includes antennas 311 to 313, a power phase calculation unit 370, transmission processing units 330a to 330c, and modulation symbol generation units 340a to 340d, and the radio base station device 300 of the first embodiment. The same reference numerals (311, 312, 330 a, 330 b, 340 a to 340 c) are given to the same configurations as those in FIG. The modulation symbol generation units 340a to 340d have the same configuration as the modulation symbol generation unit 340 of the first embodiment shown in FIG. 9, and hereinafter, any one or all of the modulation symbol generation units 340a to 340d are shown. In this case, the modulation symbol generator 340 is referred to. Further, the transmission processing units 330a to 330c have the same configuration as the transmission processing unit 330 shown in FIG. 10, and hereinafter, when any one or all of the transmission processing units 330a to 330c are shown, transmission processing is performed. This is referred to as part 330.

The modulation symbol 340d receives information bits for the terminal device 200c, and outputs a modulation symbol obtained by modulating the input information bits to the transmission processing unit 330c. The transmission processing unit 330c generates a transmission signal from the modulation symbols output from the modulation symbol generation units 340a and 340d according to the superimposed power phase designation information output from the power phase calculation unit 370, and transmits the generated transmission signal to the antenna 313. To the terminal devices 100 and 200c.
The power phase calculation unit 370 is connected to the antennas 311 to 313, the superimposed power information transmitted by the terminal devices 200 a to 200 c via the antennas 311 to 313, the phase difference information and the power ratio information transmitted by the terminal device 100, and The superimposed power is calculated according to the information, and the information is output to the transmission processing units 330a to 330c.

Next, FIG. 19 is a schematic block diagram illustrating the configuration of the power phase calculation unit 370. The power phase calculation unit 370 includes a phase difference information detection unit 371, a power ratio information detection unit 372, superimposed power information detection units 373 to 375, and an information calculation unit 376.
The phase difference information detection unit 371 is connected to the antennas 311 to 313, detects phase difference information transmitted by the terminal device 100 from the received signal, and outputs the phase difference information to the information calculation unit 376. The power ratio information detection unit 372 is connected to the antennas 311 to 313, detects power ratio information transmitted by the terminal device 100 from the received signal, and outputs the power ratio information to the information calculation unit 376.
The superimposed power information detection unit 373 is connected to the antenna 311, detects the superimposed power information transmitted by the terminal device 200 a, and outputs it to the information calculation unit 376. The superimposed power information detection unit 374 is connected to the antenna 312, detects the superimposed power information transmitted by the terminal device 200 b, and outputs it to the information calculation unit 376. The superimposed power information detection unit 375 is connected to the antenna 313, detects the superimposed power information transmitted by the terminal device 200c, and outputs the detected information to the information calculation unit 376.

  The information calculation unit 376 includes phase difference information output from the phase difference information detection unit 371, power ratio information output from the power ratio information detection unit 372, and superimposed power information output from the superimposed power information detection units 373 to 375. The superimposed power phase designation information for the transmission processing unit 330a, the superimposed power phase designation information for the transmission processing unit 330b, and the superimposed power phase designation information for the transmission processing unit 330c are calculated, and the transmission processing units 330a to 330c are calculated. 330c is output to each.

Next, processing performed by the information calculation unit 376 will be described. Here, the power allocated to the modulation symbol for the terminal apparatus 100 transmitted from the antenna 311 is p ₁₁ , the power allocated to the modulation symbol for the terminal apparatus 100 transmitted from the antenna 312 is p _21, and the power to the terminal apparatus 100 transmitted from the antenna 313 is the power allocated to modulation symbols and _{p 31.}
The power allocated to modulation symbols for the terminal device 200a to be transmitted from the antenna 311 and _{p 12,} the power allocated to modulation symbols for terminals 200b to be transmitted from the antenna 312 and _{p 23,} the modulation symbols for terminal 200c to be transmitted from the antenna 313 Let p ₃₄ be the power to be allocated. The total power p ₁ (= p ₁₁ + p ₂₁ + p ₃₁ ) allocated to the modulation symbols for the terminal apparatus 100 is constant, and is determined by, for example, the rated transmission power of the radio base station apparatus 300.

  When performing communication based on maximum ratio combining (MRC), the information calculation unit 376 calculates power and phase for performing processing represented by the following equations (6-1) to (6-3).

Here, _{x 1} is a modulation symbol for the terminal apparatus _{100, y 11} is a modulation symbol subjected to power conversion and phase rotation to be transmitted from the antenna 311 to the terminal device 100, the power phase control of the transmission processing unit 330a This is a modulation symbol output from the unit 331. y ₂₁ is a modulation symbol output from the power phase control unit 331 of the transmission processing unit 330b, similarly to y ₁₁ . y ₃₁ is a modulation symbol output from the power phase control unit 331 of the transmission processing unit 330c, similarly to y ₁₁ .

Hereinafter, the lower limit values min_p ₁₁ , min_p ₂₁ , and min_p ₃₁ , the transmission amplitude P 1 of the modulation symbol for the terminal device 100 transmitted from the antenna 311 in the case of performing communication based on the normal maximum ratio combining, and the antenna 312 The case is classified according to the magnitude relationship between the transmission amplitude P2 of the modulation symbol for the terminal apparatus 100 to be transmitted and the transmission amplitude P3 of the modulation symbol for the terminal apparatus 100 transmitted from the antenna 313, and the information calculation unit 376 of each case The operation will be described. Here, min_p ₃₁ is a lower limit value of transmission power in the radio base station apparatus 303 of the modulation symbol with which the terminal apparatus 200c can detect the modulation symbol for the terminal apparatus 100.
However, the transmission amplitudes P1, P2, and P3 are as follows.
P1 = | h ₁ | / √ (| h ₁ | ² + | h ₂ | ² + | h ₃ | ² ) · √p ₁
P2 = | h ₂ | / √ (| h ₁ | ² + | h ₂ | ² + | h ₃ | ² ) · √p ₁
P3 = | h ₃ | / √ (| h ₁ | ² + | h ₂ | ² + | h ₃ | ² ) · √p ₁

<Case 1>
The transmission power of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is larger than the square root of the lower limit value of the transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and is transmitted from the antenna 312. 100 is larger than the square root of the lower limit value of the transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100, and the transmission amplitude of the modulation symbol for the terminal device 100 transmitted from the antenna 313 is When the terminal device 200c is larger than the square root of the lower limit value of the transmission power with which the modulation symbol for the terminal device 100 can be detected, that is, P1> (min_p ₁₁ ) ^1/2 , P2> (min_p ₂₁ ) ^1/2 , and ^{_{, P3> (min_p 31) 1}} / If (condition 3-1) is satisfied, the information calculating unit 376 outputs the object superimposed power phase designation information represented by the formula (7-1) to the transmission processing section 330a, the table by the formula (7-2) The superimposed power phase designation information is output to the transmission processing unit 330b, and the superimposed power phase designation information represented by Expression (7-3) is output to the transmission processing unit 330c.

<Case 2>
The transmission amplitude of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is equal to or less than the square root of the lower limit value of the transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and the terminal transmitted from the antenna 312. The transmission amplitude of the modulation symbol for apparatus 100 is larger than the square root of the lower limit value of the transmission power at which terminal apparatus 200b can detect the modulation symbol for terminal apparatus 100, and the transmission amplitude of the modulation symbol for terminal apparatus 100 transmitted from antenna 313. Is larger than the square root of the lower limit value of the transmission power at which the terminal device 200c can detect the modulation symbol for the terminal device 100, and the total transmission power of the modulation symbol for the terminal device 100 is the modulation symbol for the terminal device 100 by the terminal device 200a. Transmitter power that can be detected Of the transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100 and the lower limit value of the transmission power at which the terminal device 200c can detect the modulation symbol for the terminal device 100. That is, P1 ≦ (min_p ₁₁ ) ^1/2 , P2> (min_p ₂₁ ) ^1/2 , P3> (min_p ₃₁ ) ^1/2 , and p1 ≧ min_p ₁₁ + min_p ₂₁ + min_p ₃₁ (Condition 3 -2) is satisfied, the information calculation unit 376 sets the modulation symbols for the terminal device 100 to y ₁₁ , y ₂₁ , and y ₃₁ expressed by the following equations (8-1) to (8-3). The superimposed power phase designation information represented by the following equation (9-1) is output to the transmission processing unit 330a, and is represented by the following equation (9-2) to the transmission processing unit 330b. The superimposed power phase designation information is output, and the superimposed power phase designation information represented by the following equation (9-3) is output to the transmission processing unit 330c.

Based on the superimposed power phase designation information described above, the power phase control unit 331 determines the propagation path between the antenna 311 and the terminal apparatus 100 whose propagation path state is not good according to the superimposed power phase information calculated by the information calculation unit 325. Is assigned a lower limit min_p ₁₁ of transmission power equal to or greater than the transmission amplitude P1. As a result, the terminal device 100 cannot obtain the transmission diversity effect as high as the maximum ratio combining, but can obtain the transmission diversity effect exceeding the equal gain combining, and the terminal device 200a is self-terminal multiplexed by SPC. Detection of modulation symbols for the device can be performed.
Further, in case 2, the case where the transmission power from the antenna 311 to the terminal device 100 is smaller than the lower limit value min_p ₁₁ is shown, but the information calculation unit 325 is similar to the case of the antenna 311 in the case of the antennas 312 and 311. Then, the superimposed power phase designation information is calculated, and power / phase control is performed so that the terminal devices 200a to 200c can detect modulation symbols for the terminal device itself.

<Case 3>
The transmission amplitude of the modulation symbol transmitted from the antenna 311 to the terminal device 100 is equal to or less than the square root of the lower limit value of the transmission power at which the terminal device 200a can detect the modulation symbol for the terminal device 100, and the terminal transmitted from the antenna 312. The transmission amplitude of the modulation symbol for apparatus 100 is equal to or less than the square root of the lower limit of transmission power at which terminal apparatus 200b can detect the modulation symbol for terminal apparatus 100, and the transmission of the modulation symbol to terminal apparatus 100 transmitted from antenna 313. The amplitude is larger than the square root of the lower limit value of the transmission power at which the terminal device 200c can detect the modulation symbol for the terminal device 100, and the total transmission power of the modulation symbol for the terminal device 100 is the modulation symbol for the terminal device 100 by the terminal device 200a. Transmitter that can detect Of the transmission power at which the terminal device 200b can detect the modulation symbol for the terminal device 100 and the lower limit value of the transmission power at which the terminal device 200c can detect the modulation symbol for the terminal device 100. That is, P1 ≦ (min_p ₁₁ ) ^1/2 , P2 ≦ (min_p ₂₁ ) ^1/2 , P3> (min_p ₃₁ ) ^1/2 , and p1 ≧ min_p ₁₁ + min_p ₂₁ + min_p ₃₁ (Condition 3 -3) is satisfied, the information calculation unit 376 sets the modulation symbols for the terminal device 100 to y ₁₁ , y ₂₁ , and y ₃₁ expressed by the following equations (10-1) to (10-3). The superimposed power phase designation information represented by the following equation (11-1) is output to the transmission processing unit 330a, and the following equation (11-2) is output to the transmission processing unit 330b. The superimposed power phase designation information represented by the following equation (11-3) is output to the transmission processing unit 330c.

Based on the superimposed power phase designation information described above, the power phase control unit 331 determines the propagation path between the antenna 311 and the terminal apparatus 100 whose propagation path state is not good according to the superimposed power phase information calculated by the information calculation unit 325. Is assigned a lower limit value min_p ₁₁ of transmission power greater than or equal to the transmission amplitude P 1, and a lower limit value min_p ₁₁ of transmission power greater than or equal to the transmission amplitude P 2 for the propagation path between the antenna 312 and the terminal device 100 with a poor propagation path state. Assign. As a result, the terminal device 100 cannot obtain the transmission diversity effect as high as the maximum ratio combining, but can obtain the transmission diversity effect exceeding the equal gain combining, and the terminal device 200a is self-terminal multiplexed by SPC. Detection of modulation symbols for the device can be performed.
Moreover, in Case 3, the transmission power from the antenna 311 to the terminal device 100 is less than the lower limit value min_p _11, and the transmission power from the antenna 312 to the terminal device 100, the case lower limit min_p21 smaller, Similarly, in the case of the combination of antennas 312, 313 and the combination of antennas 311, 313, information calculation section 325 also calculates superimposed power phase designation information, and terminal devices 200a-200c provide modulation symbols for the own terminal device. Power / phase control that can detect

<Case 4>
The total transmission power of modulation symbols for terminal apparatus 100 is a lower limit value of transmission power at which terminal apparatus 200a can detect a modulation symbol for terminal apparatus 100, and a lower limit value of transmission power at which terminal apparatus 200b can detect a modulation symbol for terminal apparatus 100. when the terminal when device 200c is less than the sum of the lower limit value of the transmission power that can detect the modulation symbols for the terminal device 100, _{i.e., p1 <min_p 11 + min_p 21} + min_p 31 if (condition 3-4) is satisfied, the terminal device The transmission rate of the modulation symbol transmitted to 100 is decreased, or the transmission power of the entire signal transmitted by the radio base station apparatus 303 is increased, and processing that satisfies p1 ≧ min_p ₁₁ + min_p ₂₁ + min_p ₃₁ is performed.

  As described above, in the downlink of the radio communication system 30, the terminal device 200 transmits the lower limit value of the transmission power that can detect the modulation symbol for the terminal device 100 to the radio base station device 303, so that the radio base station device 300 However, when the power for the modulation symbol for the terminal apparatus 100 is calculated based on the maximum ratio combining, it is determined whether or not the power value transmitted by the terminal apparatus 200 is smaller. When the power of the modulation symbol for the terminal apparatus 100 is smaller than the power value transmitted by the terminal apparatus 200, the radio base station apparatus 300 performs transmission that provides a diversity effect close to maximum ratio combining to the terminal apparatus 100, and The terminal apparatus 200 can transmit a signal with power that can detect a modulation symbol for the terminal apparatus 100. At this time, terminal apparatus 200 can detect the modulation symbol for the terminal apparatus by subtracting the modulation symbol for terminal apparatus 100 from the received signal multiplexed by SPC, and can decode the information bits from the modulation symbol. .

The channel estimation value is calculated by the terminal apparatus and transmitted to the radio base station apparatus. However, the radio base station apparatus calculates the channel estimation value and transmits the calculated channel estimation value to the terminal apparatus. It is also good.
Further, in the first to third embodiments, the communication between the fixed radio base station apparatus and the movable terminal apparatus has been described. However, the configuration in which both are movable or both are both It can also be used for fixed configurations.
Further, in the first to third embodiments, the wireless communication system has been described using the configuration including the wireless base station device including a plurality of antennas. However, the wireless communication system includes a plurality of wireless base station devices and includes a plurality of wireless base stations. Each of the devices may transmit a signal to the terminal device in synchronization.

  The radio base station apparatus and terminal apparatus described above may have a computer system inside. In that case, the process of transmission and the process of reception described above are stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing the program. It will be. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

DESCRIPTION OF SYMBOLS 10, 11, 20, 30 ... Wireless communication system 100 ... Terminal device 200, 200a, 200b, 200c, 201, 201a, 201b ... Terminal device 110 ... Antenna, 111 ... Radio reception part, 112 ... GI removal part, 113 ... FFT Unit 114 ... channel estimation unit, 115 ... data detection unit, 116 ... radio transmission unit 210 ... antenna, 211 ... radio reception unit, 212 ... GI removal unit, 213 ... FFT unit 214 ... channel estimation unit, 215 ... data detection unit, 216 ... Replica generation unit 217 ... Cancellation unit, 218 ... Data detection unit, 219 ... Superposed power information calculation unit 219A ... Table unit, 220 ... Wireless transmission unit, 221 ... Superimposition power information calculation unit 222 ... Wireless transmission unit, 251 ... Channel compensator, 252 ... demodulator, 253 ... decoder 300, 301, 303 ... radio base station equipment 311, 312, 313 ... antenna, 320, 350, 370 ... power phase calculation unit 321, 371 ... phase difference information detection unit, 322, 372 ... power ratio information detection unit 323, 324, 373, 374, 375 ... superimposed Power information detection unit 325, 353, 376 ... information calculation unit 330, 330a, 330b, 330c ... transmission processing unit 340, 340a, 340b, 340c ... modulation symbol generation unit 341 ... encoding unit, 342 ... modulation unit, 331 ... power Phase control unit, 332 ... power control unit 333 ... SPC unit, 334 ... IFFT unit, 335 ... GI insertion unit, 336 ... wireless transmission unit 351, 352 ... superimposed power information detection unit 360, 360a, 360b ... transmission processing unit 361 ... Power control unit 401, 402 ... wireless relay station device

Claims (13)

In a wireless communication system having a communication device that transmits different signals from a plurality of antennas, a first terminal device, and a plurality of second terminal devices,
The communication device
Receiving power information received from each of the plurality of second terminal devices, generating a first modulation symbol for the first terminal device by transmission power based on each of the received power information, and
A plurality of transmission processing sections that multiplex the second modulation symbols for the plurality of second terminal apparatuses associated with the antennas and the first modulation symbols having the transmission power by superposition coding; Prepared,
Each of the plurality of second terminal devices includes:
Corresponding to one of the plurality of antennas, receiving a signal transmitted from the antenna, detecting the second modulation symbol from the received signal, and detecting the second modulation symbol between the antenna and the terminal device Power information indicating the transmission power of the first modulation symbol is calculated and transmitted from the propagation path characteristics of the first modulation symbol and the reception power of the first modulation symbol.
A wireless communication system. 2. The wireless communication system according to claim 1, wherein the plurality of transmission processing units transmit the first modulation symbol transmitted from the plurality of antennas with a transmission power larger than a power indicated by the power information. Each of the plurality of second terminal devices includes:
The first modulation symbol for the first terminal apparatus is detected from the signal received from the communication apparatus, and the detected second modulation symbol is subtracted from the received signal to obtain the second modulation symbol for the terminal apparatus. The wireless communication system according to claim 2, wherein a modulation symbol is detected. The power indicated by the power information transmitted by each of the plurality of second terminal devices is:
From the propagation path characteristics between the second terminal apparatus and the antenna corresponding to the second terminal apparatus, and the reception power of the first modulation symbol, the transmission power of the first modulation symbol, The wireless communication system according to claim 3, wherein the first modulation symbol is a first lower limit value that is a minimum transmission power that can be detected by a terminal device. Each of the plurality of second terminal devices includes:
A channel estimator for estimating a channel characteristic of the received signal from the received signal and calculating a channel estimation value;
Superposed power information calculation for calculating the first lower limit value of the transmission power of the first modulation symbol necessary for detecting the first modulation symbol from the channel estimation value calculated by the channel estimation unit And
The wireless communication system according to claim 4, further comprising: a wireless transmission unit that transmits the first lower limit value calculated by the superimposed power information calculation unit to the communication device as the power information. The communication device
The power phase calculation part which allocates the transmission power of the 1st modulation symbol according to the propagation path characteristic between the 1st terminal unit and each of the plurality of antennas is provided. 5. The wireless communication system according to 5. The plurality of second terminal devices are:
Superimposed power for calculating a second lower limit value for the transmission power of the second modulation symbol necessary for detecting the second modulation symbol for the terminal device from the channel estimation value calculated by the channel estimation unit With an information calculator,
The wireless transmission unit transmits the second lower limit value calculated by the superimposed power information calculation unit to the communication device,
The power phase calculation unit
In accordance with a value obtained by reducing the transmission power of the second modulation symbol corresponding to the second terminal apparatus that has transmitted the received second lower limit value to the second lower limit value, the first value is reduced by the first value. The radio communication system according to claim 6, wherein the transmission power of the modulation symbol is increased. The communication device includes two antennas as the plurality of antennas,
The total transmission power of signals transmitted from the two antennas to the first terminal device is a predetermined value,
The power phase calculation unit transmits from one of the two antennas using maximum ratio combining according to propagation path characteristics between the first terminal device and each of the two antennas. When the transmission power allocated to the first modulation symbol is less than or equal to the first lower limit value, the first modulation transmitted from the other antenna with the transmission power of the signal transmitted from the antenna as the first lower limit value The wireless communication system according to claim 6, wherein the remaining transmission power is allocated to the symbol. The communication device includes two antennas as the plurality of antennas,
The total transmission power of signals transmitted from the two antennas is a predetermined value,
The power phase calculation unit is configured to transmit the first modulation symbol transmitted from each of the two antennas using maximum ratio combining according to propagation path characteristics between the first terminal device and each of the two antennas. Assigning the second lower limit value as the transmission power of the second modulation symbol and allocating the remaining transmission power to the first modulation symbol when both of the transmission powers assigned to are less than or equal to the first lower limit value. The radio communication system according to claim 7, wherein the radio communication system is characterized. The communication device includes three antennas as the plurality of antennas,
A sum of transmission powers of signals transmitted from the three antennas to the first terminal device is determined;
The power phase calculation unit is configured to allocate the three powers by assigning transmission powers to the three antennas using maximum ratio combining according to propagation path characteristics between the first terminal device and the three antennas. When the transmission power allocated to the first modulation symbol transmitted from any one of the antennas is equal to or lower than the first lower limit value, the transmission power of the first modulation symbol transmitted from the antenna is The wireless communication system according to claim 6, wherein the first lower limit value is assigned and the remaining transmission power is assigned to the first modulation symbol transmitted from another antenna. A second terminal device in a wireless communication system having a communication device that transmits different signals from each of a plurality of antennas, a first terminal device, and a plurality of second terminal devices,
From the propagation path characteristics between the antenna associated with the own terminal apparatus among the plurality of antennas and the own terminal apparatus, and the received power of the first modulation symbol for the first terminal apparatus, the first While calculating and transmitting power information indicating the transmission power of the modulation symbol,
A terminal apparatus that receives a signal transmitted from the associated antenna and detects a second modulation symbol from the received signal. A communication device in a wireless communication system having a communication device that transmits different signals from each of a plurality of antennas, a first terminal device, and a plurality of second terminal devices,
Receiving power information received from each of the plurality of second terminal apparatuses, generating a first modulation symbol for the first terminal apparatus by transmission power based on each of the power information, and
A plurality of transmission processes for multiplexing the second modulation symbols for the plurality of second terminal apparatuses associated with the plurality of antennas and the first modulation symbols having the transmission power by superposition coding. A communication device. In a wireless communication system having a communication device that transmits different signals from a plurality of antennas, a first terminal device, and a plurality of second terminal devices,
The communication device receives power information received from each of the plurality of second terminal devices, and generates a first modulation symbol for the first terminal device based on transmission power based on each of the power information. ,
The communication device multiplexes the second modulation symbol for the second terminal device associated with each of the antennas and the first modulation symbol of the transmission power by superposition coding;
Each of the plurality of second terminal apparatuses is associated with one of the plurality of antennas, receives a signal transmitted from the antenna, and detects the second modulation symbol from the received signal And calculating and transmitting power information indicating transmission power of the first modulation symbol from propagation path characteristics between the antenna and the terminal device and received power of the first modulation symbol; A wireless communication method comprising:

Images