JP6538589B2 - Wireless communication apparatus and interference reduction method - Google Patents

Description

  The present invention relates to a wireless communication apparatus and an interference reduction method.

When a plurality of terminal devices communicate with a base station apparatus simultaneously using the same frequency band as in CDMA (Code Division Multiple Access), multi-user interference occurs because the plurality of terminal devices use the same frequency band. Transmission quality is greatly degraded. As a technique for reducing transmission quality degradation due to multiuser interference, a multistage interference canceller (SIC) is known (see, for example, Non-Patent Document 1). In this technique, an interference replica signal of interference given to another terminal device is generated from demodulation information of a certain terminal device, and the generated interference replica signal is removed from the received signal before the other terminal device Demodulate.
When the base station apparatus sequentially demodulates the transmission signal of each terminal apparatus by SIC, if the signal-to-interference-plus-noise ratio (SINR) is different for each terminal apparatus, some of the terminal apparatuses There is a problem that the demodulation characteristic of Therefore, transmission power control (TPC: Transmit Power Control) is required in order to make the SINRs of all terminal apparatuses constant at the time of demodulation even when SIC is applied (see, for example, Non-Patent Document 2).

FIG. 6 is a diagram showing an example of a configuration of a conventional terminal device 50 supporting CDMA communication.
The terminal device 50 includes an antenna 51, a reception radio unit 52, a channel estimation unit 53, a RAKE combining unit 54, a demodulation unit 55, a modulation unit 56, a spreading unit 57, and a transmission power control unit 58. And a transmission radio unit 59.
The antenna 51 receives the signal transmitted from the base station apparatus. Also, the antenna 51 transmits a signal to the base station apparatus. The reception radio unit 52 performs frequency conversion and conversion to a digital signal on the signal received by the antenna 51. The channel estimation unit 53 calculates the correlation between the training signal known also in the terminal apparatus transmitted from the base station apparatus and the digital signal converted by the reception radio unit 52, thereby calculating CSI (Channel State Information: channel state). Information). RAKE combining unit 54 RAKEs the digital signal converted by reception radio unit 52 using a known spreading code and an estimated value of CSI even in a terminal device used for spreading processing in the base station device. Do the composition. The demodulation unit 55 performs error correction decoding on the RAKE-combined signal and performs multi-level demodulation to restore the signal transmitted by the base station apparatus. The modulation unit 56 performs multi-level modulation on the transmission information to be transmitted and performs error correction coding. Spreading section 57 performs code spreading on the transmission information subjected to multi-level modulation and error correction coding by modulation section 56 using a predetermined spreading code unique to each terminal apparatus. The transmission power control unit 58 performs transmission power control on the transmission information code-spread by the spreading unit 57 in accordance with the transmission power control information obtained by the demodulation unit 55. The transmission radio unit 59 converts the transmission power controlled digital signal into an analog signal and performs frequency conversion. The frequency-converted signal is transmitted from the antenna 51 to the base station apparatus.

FIG. 7 is a diagram showing an example of a configuration of a base station apparatus 60 having a CDMA communication function and a multi-stage interference canceller function.
The base station apparatus 60 includes an antenna 61, a reception radio unit 62, a reception processing determination unit 63, an a priori channel estimation unit 64, a transmission power control amount calculation unit 65, a modulation unit 66, a diffusion unit 67, Transmission radio unit 68, demodulation order determining units 69-1 to 69-k (k is an integer of 2 or more), channel estimation units 70-1 to 70-k, RAKE combining units 71-1 to 71-k , Demodulation units 72-1 to 72-k, interference replica signal generation units 73-1 to 73-k, and subtraction units 74-1 to 74-k.
The antenna 61 receives the signal transmitted from the terminal device. Also, the antenna 61 transmits a signal to the terminal device. The reception radio unit 62 performs frequency conversion and conversion to a digital signal on the reception signal transmitted from the terminal device and received through the antenna 61. The reception process determination unit 63 determines whether the received signal is for performing pre-CSI estimation necessary for transmission power control or for simultaneously receiving information from a plurality of terminal devices. The prior channel estimation unit 64 estimates CSI by calculating the correlation between a known training signal and a received digital signal in the base station apparatus transmitted from the terminal apparatus. The transmission power control amount calculation unit 65 calculates the control amount of the transmission power of each terminal apparatus based on the CSI estimated by the prior channel estimation unit 64. The modulation unit 66 performs multi-level modulation on the transmission power control amount information, which is information indicating the control amount of the transmission power of each terminal device calculated by the transmission power control amount calculation unit 65, and performs error correction coding. Spreading section 67 performs code spreading on the transmission information subjected to multi-level modulation and error correction coding by modulation section 66 using a predetermined spreading code unique to each terminal apparatus. The transmission radio unit 68 converts the transmission information code-spread by the spreading unit 67, that is, the transmission signal into an analog signal, converts the frequency thereof, and transmits the signal through the antenna 61.

  The demodulation order determination unit 69 determines at least one terminal device not demodulated by the demodulation unit 72. For example, the demodulation order determination unit 69 may randomly determine one of the terminal devices not demodulated by the demodulation unit 72. For example, the demodulation order determination unit 69 may estimate CSI of all the terminal devices from the received signal, and may determine one with relatively high amplitude. For example, the demodulation order determination unit 69 may estimate CSI of all the terminals from the received signal, and may determine the one with the largest amplitude. The demodulation order determination unit 69 determines a terminal device to be demodulated every time the demodulation process is performed. The channel estimation unit 70 estimates CSI by calculating the correlation between the training signal known also in the base station apparatus transmitted from the terminal apparatus and the digital signal received by the antenna 61. RAKE combining section 71 performs RAKE combining on the received digital signal using a spreading code known also in the base station apparatus used for spreading processing in the terminal apparatus and the estimated CSI estimation value. . The demodulator 72 performs multi-level demodulation and error correction decoding on the RAKE-combined signal. The interference replica signal generation unit 73 generates an interference replica signal based on the demodulated reception signal, the spreading code used in the determined terminal apparatus, and the estimated CSI. The subtraction unit 74 subtracts the interference replica signal from the reception signal converted into the digital signal. By this means, the base station apparatus can reduce multi-user interference by the determined terminal apparatus when demodulating the received signal of the terminal apparatus in the next communication.

Teiji Tadakawa, "W-CDMA mobile communication system", Maruzen Co., Ltd., June 25, 2001, p56-77 J. G. Andrews and T. H. Meng, "Optimum Power Control for Successive Interference Cancellation with Imperfect Channel Estimation," IEEE Trans. Wireless Comm. Vol. 2, no. 2, pp. 375-383, Mar. 2003.

  However, in the case of simultaneously receiving signals from a plurality of terminal apparatuses by the base station apparatus, multi-user interference occurs and transmission quality is degraded. The multi-stage interference canceller is a technology to reduce multi-user interference, but in an environment with multi-user interference, the accuracy of the interference replica signal is degraded due to an error in the CSI estimation accuracy. The received signal from which the interference replica signal has been removed contains a residual interference component. Other than multi-user interference, interference between multiple waves due to noise or multiple wave propagation also causes an error in CSI estimation accuracy, and residual interference components are included. Therefore, there is a problem that the transmission quality improvement effect of the multistage interference canceller is weakened by the residual interference component.

  In view of the above circumstances, the present invention aims to provide a technique for reducing residual interference components generated after interference removal processing.

One aspect of the present invention is a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus is performed. A first channel estimation unit for estimating in advance first channel state information between the own apparatus and each of the transmitters; and the transmission based on the first channel state information estimated in advance. A transmission power control amount calculation unit that calculates a transmission power control amount of each device; a second channel estimation unit that estimates second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmission devices; predicted value of the reception signal obtained from the first channel state information and training signal before Symbol transmission power control amount and the already known, and fruit of the received signal Based on the value, a weight calculation unit for calculating a second weight to the first weight and the second channel state information for the first channel state information, and the first channel state information, the second A weighting combining unit for weighting and combining the first channel state information and the second channel state information based on the channel state information, the first weight, and the second weight; It is a wireless communication apparatus provided.

One aspect of the present invention is a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus is performed. A first channel estimation unit for estimating in advance first channel state information between the own apparatus and each of the transmitters; and the transmission based on the first channel state information estimated in advance. A transmission power control amount calculation unit that calculates a transmission power control amount of each device; a second channel estimation unit that estimates second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmission devices; The first channel state information, the first channel state information, the transmission power control amount, and the first channel obtained from a known training signal. First weight for the first channel state information and second for the second channel state information based on channel state information obtained by adding an error due to interference to channel state information and the second channel state information. The first channel state is calculated based on a weight calculation unit that calculates a weight, the first channel state information, the second channel state information, the first weight, and the second weight. And a weight combining unit configured to weight and combine information and the second channel state information.

One aspect of the present invention is a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus is performed. A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices; a fourth channel estimation unit for estimating a fourth channel state information in the current time of communication from a received signal received simultaneously from said plurality of transmitting apparatuses, the third channel state information and the previous SL transmission power control amount and the already predicted value of the reception signal obtained from the training signal of knowledge, and on the basis of the measured values of the received signal, to said third channel state information A weight calculation unit that calculates a weight of 3 and a fourth weight for the fourth channel state information, the third channel state information, the fourth channel state information, the third weight, and And a weighting and combining unit that weights and combines the third channel state information and the fourth channel state information based on a fourth weight.

One aspect of the present invention is a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus is performed. A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices; A fourth channel estimation unit configured to estimate fourth channel state information at the time of this communication from received signals simultaneously received from the plurality of transmitting devices, the third channel state information, and the third channel state information; A channel state obtained by adding an error due to interference to the third channel state information obtained from the transmission power control amount and a known training signal A weight calculation unit configured to calculate a third weight for the third channel state information and a fourth weight for the fourth channel state information based on the second channel state information and the fourth channel state information; Weighting the third channel state information and the fourth channel state information on the basis of the fourth channel state information, the fourth channel state information, the third weight, and the fourth weight; And a weighting and combining unit for combining.

One aspect of the present invention is interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus A reduction method, comprising: a first channel estimation step of estimating in advance first channel state information between the own apparatus and each of the transmission devices; and based on the first channel state information estimated in advance A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices, and second channel estimation of estimating second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmission devices a step is determined from the first channel state information and training signal before Symbol transmission power control amount and the already known the Predicted value of the signal signal, and based on the measured value of the received signal, and the weight calculation step of calculating a second weight to the first weight and the second channel state information for the first channel state information, The first channel state information and the second channel state information based on the first channel state information, the second channel state information, the first weight, and the second weight. And weighting and combining the weighting and combining.
One aspect of the present invention is interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus A reduction method, comprising: a first channel estimation step of estimating in advance first channel state information between the own apparatus and each of the transmission devices; and based on the first channel state information estimated in advance A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices, and second channel estimation of estimating second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmission devices And step (e), the first channel state information, the first channel state information, the transmission power control amount, and a known trainee. A first weight for the first channel state information, based on channel state information obtained by adding an error due to interference to the first channel state information, which is obtained from the first channel state information, and A weight calculation step of calculating a second weight for the second channel state information, the first channel state information, the second channel state information, the first weight, and the second weight And weighting and combining the first channel state information and the second channel state information on the basis of the first channel state information and the second channel state information.

One aspect of the present invention is interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus It is a reduction method, Comprising: The transmission power control which calculates the transmission power control amount of each said transmitter based on the 3rd channel state information between the own apparatus estimated at the time of last communication, and each said transmitter. and quantity calculation step, and a fourth channel estimation step of estimating a fourth channel state information at the time of the current communication from the reception signal received simultaneously from said plurality of transmitting apparatuses, the third channel state information and the previous SL transmit power predicted value of the reception signal obtained from the training signal of the controlled variable and already known, and based on the measured value of the received signal, before Calculating a third weight for the third channel state information and a fourth weight for the fourth channel state information, the third channel state information, and the fourth channel state information; An interference reduction method including weighting and combining the third channel state information and the fourth channel state information based on the fourth weight and the fourth weight. .
One aspect of the present invention is interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system in which interference is reduced by a successive interference canceler when demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus It is a reduction method, Comprising: The transmission power control which calculates the transmission power control amount of each said transmitter based on the 3rd channel state information between the own apparatus estimated at the time of last communication, and each said transmitter. An amount calculating step, a fourth channel estimating step of estimating fourth channel state information at the time of this communication from received signals simultaneously received from the plurality of transmitters, the third channel state information, the third The third channel state information obtained from the channel state information, the transmission power control amount, and the known training signal is Calculating a third weight for the third channel state information and a fourth weight for the fourth channel state information, based on the channel state information to which the error due to the second channel state information is added and the fourth channel state information The third channel state information and the fourth channel state information based on the calculating step, the third channel state information, the fourth channel state information, the fourth weight, and the fourth weight; And c) weighting and combining channel state information of B.

  The present invention makes it possible to reduce residual interference components that occur after interference removal processing.

FIG. 1 is a block diagram showing a wireless communication system 100 of the present invention. It is a block diagram which shows the internal structure of the base station apparatus 2 in 1st Embodiment. It is a flowchart which shows the flow of a process of the base station apparatus 2 in 1st Embodiment. It is a block diagram which shows the internal structure of the base station apparatus 2a in 2nd Embodiment. It is a flowchart which shows the flow of a process of the base station apparatus 2a in 2nd Embodiment. It is a figure which shows the example of a structure of the conventional terminal device 50 corresponding to a CDMA communication. It is a figure which shows the example of a structure of the base station apparatus 60 which has a function of CDMA communication, and a multi-stage interference canceller function.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a wireless communication system 100 of the present invention. The wireless communication system 100 includes a plurality of terminal devices 1-1 to 1-k (k is the number of terminal devices performing wireless communication at the same timing) and the base station device 2. The terminal devices 1-1 to 1-k and the base station device 2 perform communication according to a code division multiple access method, that is, a CDMA method. Each of the terminal devices 1-1 to 1-k has an internal configuration similar to that of the terminal device 50 shown in FIG.

First Embodiment
FIG. 2 is a block diagram showing an internal configuration of the base station device 2 in the first embodiment.
The base station apparatus 2 includes an antenna 21, a wireless reception unit for reception 22, a reception processing determination unit 23, an a priori channel estimation unit 24, a transmission power control amount calculation unit 25, a modulation unit 26, a diffusion unit 27, Radio section for transmission 28, demodulation order determination units 29-1 to 29-k, weight calculation unit 30, channel estimation units 31-1 to 31-k, weighting combination units 32-1 to 32-k, RAKE combining units 33-1 to 33-k, demodulation units 34-1 to 34-k, interference replica signal generation units 35-1 to 35- (k-1), and subtraction units 36-1 to 36- ( k-1).

The antenna 21 receives signals transmitted from the terminal devices 1-1 to 1-k. The antenna 21 outputs the reception signal to the reception radio unit 22. The received signals include the signals transmitted from the terminal devices 1-1 to 1-k. Also, the antenna 61 transmits a signal to the terminal devices 1-1 to 1-k.
The reception radio unit 22 receives the reception signal output from the antenna 21 as an input. The reception radio unit 22 performs frequency conversion and conversion to a digital signal on the input reception signal. The reception radio unit 22 outputs the reception signal converted to the digital signal to the reception processing determination unit 23. The reception radio unit 22 outputs the reception signal to the prior channel estimation unit 24 or the demodulation order determination unit 29-1 according to the determination result of the reception process determination unit 23. When the reception signal is output to demodulation order determination unit 29-1, the reception signal is also output to channel estimation unit 31-1, weighting combination unit 32-1, RAKE combination unit 33-1, and subtraction unit 36-1. Is output.

  The reception process determination unit 23 simultaneously receives information from a plurality of terminal devices 1-1 to 1-k, whether the received signal is for performing pre-CSI estimation necessary for transmission power control. Determine if it is When the received signal is for performing a priori CSI estimation necessary for transmission power control, the reception processing determination unit 23 causes the prior channel estimation unit 24 to output the received signal. Further, in the case where the received signal is for simultaneously receiving information from the terminal devices 1-1 to 1-k, the reception processing determination unit 23 demodulates the received signal in the demodulation order determination unit 29-. 1. Output to channel estimation unit 31-1, weighting combining unit 32-1, RAKE combining unit 33-1, and subtraction unit 36-1.

The prior channel estimation unit 24 receives the digital signal output from the reception radio unit 22 and the training signal known from the base station apparatus transmitted from the terminal apparatuses 1-1 to 1-k. The prior channel estimation unit 24 estimates CSI by calculating the correlation between the input digital signal and the training signal. In the following description, the CSI estimated by the a priori channel estimation unit 24 will be referred to as a prior estimated CSI (first channel state information). The prior channel estimation unit 24 outputs the estimated previously estimated CSI to the transmission power control amount calculation unit 25. CSI is channel state information.
The transmission power control amount calculation unit 25 receives the pre-estimated CSI output from the pre-channel estimation unit 24 as an input. The transmission power control amount calculation unit 25 calculates transmission power control amounts of the terminal devices 1-1 to 1-k based on the input pre-estimated CSI. The transmission power control amount calculation unit 25 outputs the calculated transmission power control amount to the modulation unit 26.

The modulation unit 26 receives the transmission power control amounts of the terminal devices 1-1 to 1-k output from the transmission power control amount calculation unit 25. The modulation unit 26 performs multi-level modulation on the input transmission power control amount and performs error correction coding.
Spreading section 27 receives as input transmission information that has been multi-level modulated by modulation section 26 and error correction coded. The spreading unit 27 code-spreads the input transmission information using a predetermined spreading code unique to each of the terminal devices 1-1 to 1-k.
The transmission radio unit 28 converts the transmission information code-spread by the spreading unit 27, that is, the transmission signal into an analog signal, converts the frequency into an analog signal, and transmits the signal through the antenna 21.

  The demodulation order determination units 29-1 to 29-k determine at least one of the terminal devices 1-1 to 1-k not demodulated by the demodulation units 34-1 to 34-k. For example, the demodulation order determination units 29-1 to 29-k may randomly determine one of the terminal devices not demodulated by the demodulation units 34-1 to 34-k. For example, the demodulation order determination units 29-1 to 29-k may estimate CSI of all the terminal apparatuses from the received signal, and may determine one with relatively high amplitude. For example, the demodulation order determination units 29-1 to 29-k may estimate the CSI of all the terminal apparatuses from the received signal, and may determine the one with the largest amplitude. The demodulation order determination units 29-1 to 29-k determine terminal devices to be demodulated each time the demodulation process is performed. In the following description, the terminal device to be demodulated determined by the demodulation order determination units 29-1 to 29-k will be referred to as a target terminal device.

  The weight calculation unit 30 may use the pre-estimated CSI and the CSI at the time of the current communication estimated by the channel estimation units 31-1 to 31-k (hereinafter referred to as "currently estimated CSI at the time of current communication") (second channel state). Information), the transmission power control amount calculated by the transmission power control amount calculation unit 25, and a training signal known in the base station device 2 transmitted from the terminal devices 1-1 to 1-k are input. The weight calculator 30 calculates the weight for the previously estimated CSI and the weight for the currently estimated communication CSI based on the input previously estimated CSI, the current communication estimated CSI, the transmission power control amount, and the training signal. Do. The weight calculation unit 30 outputs the calculated weight for the pre-estimated CSI and the weight for the current communication estimated CSI to the weight combining units 32-1 to 32-k.

  The channel estimation unit 31-1 inputs a known training signal in the base station apparatus 2 transmitted from the target terminal apparatus determined by the demodulation order determination unit 29-1 and the received digital signal. The channel estimation unit 31-1 estimates the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal. The channel estimation units 31-2 to 31-k are the training units known in the base station apparatus 2 transmitted from the target terminal apparatus determined by the demodulation order determination units 29-2 to 29-k and the subtraction unit 36-1. The digital signal subtracted by -36- (k-1) is input. The channel estimation units 31-2 to 31-k estimate the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal. The channel estimation units 31-1 to 31-k output the estimated current-time estimated CSI to the weight calculation unit 30 and the weight combination units 32-1 to 32-k.

  Weighting combining section 32-1 includes a weight for the pre-estimated CSI output from weight calculating section 30, a weight for the current communication estimated CSI, a pre-estimated CSI output from prior channel estimation section 24, and a channel estimation section 31-. The current communication estimated CSI output from 1 and the received signal are input. The weight combining unit 32-1 uses the weight for the input pre-estimated CSI and the weight for the current communication estimated CSI to weight and combine the pre-estimated CSI and the current communication estimated CSI. The weighting and combining units 32-2 to 32-k perform the same processing as the weighting and combining unit 32-1. The weighting and combining units 32-1 to 32-k are configured to perform RAKE combining units 33-1 to 33-k and interference replica signal generation units 35-1 to 35 for CSI (hereinafter referred to as “combined CSI”) subjected to weighting and combining. Output to-(k-1).

  RAKE combining unit 33-1 includes the received digital signal, a spreading code known in base station apparatus 2 used for the spreading process by the target terminal determined by demodulation order determining unit 29-1, and a weight combining unit The composite CSI output from 32-1 is used as an input. The RAKE combining unit 33-1 performs RAKE combining on the input digital signal using the spreading code and the combined CSI. The RAKE combiners 33-2 to 33-k are the digital signals subtracted by the subtractors 36-1 to 36- (k-1) and the target terminals determined by the demodulation order determiners 29-2 to 29-k. The base station apparatus 2 used for the spreading process in the apparatus receives as input the spreading code known in the base station apparatus 2 and the combined CSI output from the weight combining sections 32-2 to 32-k. The RAKE combiners 33-2 to 33-k perform RAKE combining on the input digital signals using the spreading code and the combined CSI. The RAKE combining units 33-1 to 33-k output the signals subjected to the RAKE combining to the demodulation units 34-1 to 34-k.

  The demodulators 34-1 to 34-k receive as input the signals RAKE-combined by the RAKE combining units 33-1 to 33-k. The demodulation units 34-1 to 34-k perform error correction decoding on the input signals to perform multi-level demodulation, and restore the signals transmitted by the terminal devices 1-1 to 1-k. Here, the demodulation information 1 to k demodulated by the demodulation units 34-1 to 34-k corresponds to any one of the signals transmitted from the terminal devices 1-1 to 1-k. The demodulators 34-1 to 34- (k-1) output the demodulation information 1 to k-1 to the interference replica signal generators 35-1 to 35- (k-1).

  The interference replica signal generation units 35-1 to 35- (k-1) are demodulation information 1 to k-1 demodulated by the demodulation units 34-1 to 34- (k-1), and the demodulation order determination unit 29-1 The spreading code used in the target terminal apparatus determined by 2929-k and the combined CSI output from the weighting and combining units 32-1 to 32-k are input. The interference replica signal generation units 35-1 to 35- (k-1) generate an interference replica signal based on the input demodulation information 1 to k-1, the spreading code, and the synthesized CSI. The interference replica signal generation units 35-1 to 35- (k-1) output the generated interference replica signals to the subtraction units 36-1 to 36- (k-1).

  The subtractor 36-1 receives the interference replica signal generated by the interference replica signal generator 35-1 and the received digital signal. The subtraction unit 36-1 subtracts the interference replica signal from the input digital signal. The subtractors 36-2 to 36- (k-1) receive the interference replica signal generated by the interference replica signal generator 35-2 to 35- (k-1) and the digital signal obtained by subtraction. . The subtractors 36-2 to 36- (k-1) subtract the interference replica signal from the input digital signal.

FIG. 3 is a flowchart showing the flow of processing of the base station device 2 in the first embodiment.
The antenna 21 receives the training signal for pre-estimation transmitted from the terminal devices 1-1 to 1-k (step S101). The antenna 21 outputs the received training signal for pre-estimation to the pre-channel estimation unit 24 via the reception radio unit 22. Moreover, the antenna 21 receives the signal transmitted from the terminal devices 1-1 to 1-k. The antenna 21 outputs the received signal to the prior channel estimation unit 24 via the reception radio unit 22. The pre-channel estimation unit 24 estimates pre-estimated CSI by calculating the correlation between the training signal and the received signal (step S102). The prior channel estimation unit 24 outputs the estimated previously estimated CSI to the transmission power control amount calculation unit 25. The transmission power control amount calculation unit 25 calculates the transmission power control amount of the terminal devices 1-1 to 1-k based on the pre-estimated CSI output from the a priori channel estimation unit 24 (step S103). The transmission power control amount calculation unit 25 outputs the calculated transmission power control amount to the modulation unit 26.

  The modulation unit 26, the spreading unit 27, and the transmission wireless unit 28 perform transmission processing using the transmission power control amount output from the transmission power control amount calculation unit 25 (step S104). Specifically, first, the modulation unit 26 performs multi-level modulation on the transmission power control amount output from the transmission power control amount calculation unit 25 and performs error correction coding. Next, the spreading unit 27 performs code spreading on the transmission information using a predetermined spreading code unique to each of the terminal devices 1-1 to 1-k. The transmission radio unit 28 converts the transmission information code-spread by the spreading unit 27, that is, the transmission signal into an analog signal, converts the frequency into an analog signal, and transmits the signal through the antenna 21.

  The antenna 21 receives simultaneously the signal transmitted from each terminal device 1 (step S105). The antenna 21 demodulates combined signals of a plurality of simultaneously received signals via the reception radio unit 22 through the demodulation order determination unit 29-1, channel estimation unit 31-1, weighting combining unit 32-1, RAKE combining unit 33. -1 and output to the subtractor 36-1. The demodulation order determination unit 29-1 determines the target terminal apparatus based on the combined signal of the plurality of signals received by the antenna 21 (step S106). Here, it is assumed that the terminal device 1-1 is determined as the target terminal device. The channel estimation unit 31-1 inputs a training signal known in the base station device 2 transmitted from the terminal device 1-1 and the received digital signal. The channel estimation unit 31-1 estimates the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal (step S107). The channel estimation unit 31-1 outputs the estimated current-time estimated CSI to the weight calculation unit 30 and the weight combination unit 32-1.

The weight calculation unit 30 determines a weight w ₀ for the pre-estimated CSI based on the pre-estimated CSI, the current communication-estimated CSI output from the channel estimation unit 31-1, the transmission power control amount, and the training signal. weight _{w 1} 1 weight) and for the current communication time estimated CSI (second weighting) and calculates a (step S108). Specifically, the weight calculation unit 30 calculates a weight w ₀ and weights w ₁ according to the following equation (1) and (2).

In the above equations (1) and (2), w ₀ represents a weight for the pre-estimated CSI, w ₁ represents a weight for the current communication estimated CSI, α is a coefficient, r ₀ is a predicted value of the received signal, r ₁ represents an actual measurement value of the received signal. When the calculated value of w ₀ exceeds 1, the weight calculation unit 30 sets w ₁ = 1 and w ₀ = 0. α is an arbitrary value and may be 1. The weight calculation unit 30 outputs the calculated weight w ₀ and weight w ₁ to the weight combination unit 32-1.

Weighting and combining unit 32-1, weights the pre-estimated CSI using the weight _{w 0} which is output from the weight calculation unit 30, weighting the time communication time estimated CSI using the weight _{w 1,} each CSI after weighting The combined CSI is generated by combining (step S109). The weighting and combining unit 32-1 outputs the combined CSI to the RAKE combining unit 33-1 and the interference replica signal generation unit 35-1. The RAKE combining unit 33-1 performs RAKE combining (step S110). The demodulation unit 34-1 performs error correction decoding on the signal subjected to RAKE combining by the RAKE combining unit 33-1, performs multi-level demodulation, and restores the signal transmitted by the terminal device 1-1 (Step S111). The demodulation unit 34-1 outputs the demodulation result to the outside, and outputs the demodulation result to the interference replica signal generation unit 35-1.

  One of the demodulation order determination units 29-1 to 29-k determines whether the condition for the end of demodulation is satisfied (step S112). Specifically, one of the demodulation order determination units 29-1 to 29-k determines whether the condition for the end of the demodulation is satisfied depending on whether the power of the input digital signal falls below a predetermined threshold. Determine if If the power of the input digital signal falls below a predetermined threshold, one of the demodulation order determination units 29-1 to 29-k determines that the condition for the end of demodulation is satisfied. On the other hand, when the power of the input digital signal does not fall below the predetermined threshold, it is determined that one of the demodulation order determination units 29-1 to 29-k does not satisfy the condition for the end of demodulation. Note that the demodulation order determination units 29-1 to 29-k determine whether the condition for the end of demodulation is satisfied according to whether or not demodulation of a predetermined number (for example, k terminal devices) has been attempted. You may In this case, it is determined as follows. When demodulation of a predetermined number (for example, k terminal apparatuses) is attempted, the demodulation order determining units 29-1 to 29-k determine that the condition for the demodulation end is satisfied. On the other hand, when the demodulation for a predetermined number has not been performed, the demodulation order determination units 29-1 to 29-k determine that the condition for the demodulation end is not satisfied. If the condition for the end of demodulation is satisfied (YES in step S112), the base station device 2 ends the process.

  On the other hand, when the condition for the end of demodulation is not satisfied (step S112-NO), the interference replica signal generation unit 35-1 generates the combined CSI and the spreading code used in the target terminal device (for example, the terminal device 1-1). And an interference replica signal based on the demodulation result (step S113). The interference replica signal generation unit 35-1 outputs the generated interference replica signal to the subtraction unit 36-1. The subtraction unit 36-1 subtracts the interference replica signal from the received digital signal (step S114). The digital signal from which the interference replica signal has been subtracted is input to the subtraction unit 36-2 at the lower end and the demodulation order determination unit 29-2.

The demodulation order determination units 29-2 to 29-k determine the next target terminal device among the terminal devices 1-1 to 1-k based on the digital signal from which the interference replica signal is subtracted (step S115). .
The channel estimation units 31-2 to 31-k input a training signal known in the base station apparatus 2 transmitted from the target terminal apparatus and a digital signal that has been subtracted. The channel estimation units 31-2 to 31-k estimate the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal (step S116). The channel estimation units 31-2 to 31-k output the estimated current communication estimated CSI to the weight calculation unit 30 and the weight combination units 32-2 to 32-k.

The weight calculation unit 30 weights the previously estimated CSI based on the previously estimated CSI, the current communication estimated CSI output from the channel estimation units 31-2 to 31-k, the transmission power control amount, and the training signal. W ₀ (first weight) and weight w ₁ (second weight) for the current communication estimated CSI are calculated (step S 117). Specifically, the weight calculation unit 30 calculates a weight _{w 0} and weights _{w 1,} based on the equation (1) and (2). The weight calculation unit 30 outputs the calculated weight w ₀ and weight w ₁ to the weight combination units 32-2 to 32-k.

Weighting combining unit 32-2~32-k is to weight the pre-estimated CSI using the weight _{w 0} which is output from the weight calculation unit 30, weighting the time communication time estimated CSI using the weight _{w 1,} the weighted The synthesized CSI is generated by synthesizing each CSI of (step S118). The weighting and combining unit 32-2 to 32-k outputs the combined CSI to the RAKE combining unit 33-2 to 33-k and the interference replica signal generating unit 35-2 to 35- (k-1). The RAKE combiners 33-2 to 33-k perform RAKE combining (step S119). The demodulators 34-2 to 34-k perform error correction decoding on the signal that the RAKE combiners 33-2 to 33-k have performed RAKE combining, perform multi-level demodulation, and transmit the target terminal apparatus The signal is restored (step S120). The demodulators 34-2 to 34-k output the demodulation result to the outside, and output the demodulation result to the interference replica signal generation units 35-2 to 35- (k-1). Thereafter, the process of step S112 is performed.

According to the base station apparatus 2 configured as described above, it is possible to reduce the residual interference component generated after the interference removal process. Hereinafter, this effect will be described in detail.
The base station apparatus 2 calculates the weight for each CSI using the pre-estimated CSI and the current communication estimated CSI. Specifically, the base station apparatus 2 calculates the difference between the predicted value and the measured value of the received signal, and if the difference is small (for example, less than a threshold), determines that the time variation of CSI is small, and CSI estimated in advance The weight of the current communication estimated CSI is set small. On the other hand, if the difference is large (for example, a threshold or more), it is determined that the time variation of CSI is large, the weight of CSI estimated in advance is small, and the weight of CSI estimated this time in communication is set large. This is because if there is less interference when performing CSI estimation in advance for TPC than when multiple terminal apparatuses 1-1 to 1-k simultaneously communicate with base station apparatus 2, CSI estimated in advance is better. But the accuracy is good. On the other hand, when a long time elapses from the time when CSI estimation is performed in advance, the CSI varies with time, and the accuracy of the current communication estimated CSI becomes better than the pre-estimated CSI. Then, the base station apparatus 2 corrects the degradation of the CSI estimation accuracy due to interference by performing weighted combining with the previously estimated CSI and the current communication estimated CSI using the calculated weights. Therefore, it is possible to reduce the residual interference component generated after the interference removal process.

<Modification>
Weight calculator 30 may be configured to calculate the weights w ₀ and weights w ₁ according to the following equation (3) to (6).

In the above equations (3) and (4), w ₀ represents a weight for the pre-estimated CSI, and w ₁ represents a weight for the current communication estimated CSI. In the above equations (5) and (6), k is the identification number of the terminal device 1, n _p is the path identification number, h ₀ , k, n _p is the pre-estimated CSI of the path n _p of the terminal device k, h ₀ ′, k, n _p represent CSI obtained by adding an error due to interference to the pre-estimated CSI, and h ₁ , k, n _p represent the current communication estimated CSI of the path n _p of the terminal device k. Note that h ₀ ′, k, n _p is estimated when signals from all the terminal apparatuses 1-1 to 1-k interfere with each other based on the pre-estimated CSI, the transmission power control amount, and the known training signal. To be obtained as CSI.
Hereinafter, the effect of the above-mentioned modification is explained in detail.
In the weighting of the previously estimated CSI and the current communication estimated CSI, the above equation (5) represents error power due to interference, and equation (6) represents error power due to time variation. If the error power due to interference is large, it is considered that the reliability of the current communication estimated CSI that is susceptible to interference is low. On the other hand, when the error power due to the time variation is large, it is considered that the reliability of the previously estimated CSI susceptible to the time variation is low. Therefore, the base station apparatus 2 uses the above equations (3) and (4) and based on the error power calculated from the above equations (5) and (6), the weight of the higher reliability CSI is calculated. Calculate each weight to be large. Then, the base station apparatus 2 sets the calculated weights for the pre-estimated CSI and the current communication estimated CSI, and performs weight combination. For example, when the error power due to interference is larger than the error power due to time variation, the weight of the previously estimated CSI is increased. If the error power due to time variation is larger than the error power due to interference, the weight of the current communication estimated CSI is increased. By weight combining, the base station corrects for the degradation of the CSI estimation accuracy. Therefore, it is possible to reduce the residual interference component generated after the interference removal process.

Second Embodiment
FIG. 4 is a block diagram showing an internal configuration of the base station device 2a in the second embodiment.
The base station apparatus 2a includes an antenna 21, a reception radio unit 22a, a reception processing determination unit 23, a transmission power control amount calculation unit 25a, a modulation unit 26, a diffusion unit 27, and a transmission radio unit 28. Demodulation order determination units 29-1 to 29-k, weight calculation units 30a, channel estimation units 31a-1 to 31a-k, weighting combining units 32a-1 to 32a-k, RAKE combining units 33-1 to 33-1 33-k, demodulators 34-1 to 34-k, interference replica signal generators 35-1 to 35-k, subtractors 36-1 to 36-k, and channel estimation result holder 37 .

  The base station apparatus 2a in the second embodiment does not include the advance channel estimation unit 24, and the reception radio unit 22, transmission power control amount calculation unit 25, weight calculation unit 30, channel estimation unit 31, and weight combination unit 32. And a base station apparatus 2 in that it includes a channel estimation result storage unit 37, in place of a radio reception unit 22a, a transmission power control amount calculation unit 25a, a weight calculation unit 30a, a channel estimation unit 31a and a weighting combination unit 32a. Configuration is different. The other configuration of the base station device 2a is the same as that of the base station device 2. Therefore, the description of the entire base station apparatus 2a is omitted, and the reception radio unit 22a, the transmission power control amount calculation unit 25a, the weight calculation unit 30a, the channel estimation unit 31a, the weighting combination unit 32a, and the channel estimation result holding unit 37 are described. Do.

The reception radio unit 22a receives the reception signal output from the antenna 21 as an input. The reception radio unit 22a performs frequency conversion and conversion to a digital signal on the input reception signal. The reception radio unit 22a demodulates the received signal, which has been converted to a digital signal, into a demodulation order determination unit 29-1, a channel estimation unit 31a-1, a weighting synthesis unit 32a-1, a RAKE synthesis unit 33-1, and a subtraction unit 36. Output to -1.
Transmission power control amount calculation unit 25a holds CSI estimated in the previous communication (hereinafter referred to as "preceding communication time estimation CSI") (third channel state information) held in channel estimation result holding unit 37. Is an input. The transmission power control amount calculation unit 25a calculates the transmission power control amount of the terminal devices 1-1 to 1-k based on the input previous communication estimated time CSI. The transmission power control amount calculation unit 25 a outputs the calculated transmission power control amount to the modulation unit 26.

  The weight calculation unit 30a includes the previous communication time estimation CSI held in the channel estimation result holding unit 37, the current communication time estimation CSI (fourth channel state information) estimated by the channel estimation unit 31a, and transmission power control. The transmission power control amount calculated by the amount calculation unit 25a and the known training signal in the base station device 2a transmitted from the terminal devices 1-1 to 1-k are input. The weight calculation unit 30a is configured to apply a weight to the previous communication estimated CSI and a current communication estimated CSI based on the input previous communication estimated CSI, the current communication estimated CSI, the transmission power control amount, and the training signal. Calculate the weights. The weight calculation unit 30a outputs the calculated weight for the previous communication estimated CSI and the weight for the current communication estimated CSI to the weighting combining units 32a-1 to 32a-k.

  The channel estimation unit 31a-1 receives a training signal known in the base station apparatus 2 transmitted from the target terminal apparatus determined by the demodulation order determination unit 29-1 and the received digital signal. The channel estimation unit 31a-1 estimates the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal. The channel estimation units 31a-2 to 31a-k are the training signals known in the base station apparatus 2 transmitted from the target terminal apparatus determined by the demodulation order determination units 29-2 to 29-k, and the subtraction unit 36-1 The digital signal subtracted by -36- (k-1) is input. The channel estimation units 31a-2 to 31a-k estimate the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal. The channel estimation units 31a-1 to 31a-k output the estimated current communication estimated CSI to the weight calculation unit 30a and the weight combination units 32a-1 to 32a-k. Also, after the end of communication, the channel estimation unit 31a stores the estimated CSI in the channel estimation result holding unit 37 as the previous communication estimated CSI.

The weight combining unit 32a-1 includes a weight for the previous communication estimated CSI output from the weight calculation unit 30a and a weight for the current communication estimated CSI, and a current communication estimated CSI output from the channel estimation unit 31a-1. The previous communication time estimation CSI held in the channel estimation result holding unit 37 and the received signal are input. The weight combining unit 32a-1 uses the weight for the previous communication estimated CSI and the weight for the current communication estimated CSI to perform weight combining of the previous communication estimated CSI and the current communication estimated CSI. The weighting and combining units 32 a-2 to 32 a-k perform the same processing as the weighting and combining unit 32 a-1. The weighting and combining units 32a-1 to 32a-k output the combined CSI to the RAKE combining units 33-1 to 33-k and the interference replica signal generation units 35-1 to 35- (k-1).
The channel estimation result holding unit 37 holds the previous communication time estimation CSI estimated by the channel estimation units 31a-1 to 31a-k.

FIG. 5 is a flowchart showing the process flow of the base station device 2a in the second embodiment. In addition, about the process similar to FIG. 3, the code | symbol similar to FIG. 3 is attached | subjected in FIG. 5, and description is abbreviate | omitted. Further, it is assumed that the channel estimation result holding unit 37 holds the previous communication estimated CSI.
The transmission power control amount calculating unit 25a calculates the transmission power control amount of the terminal devices 1-1 to 1-k based on the previous communication estimated CSI held in the channel estimation result holding unit 37 (step S201). . The transmission power control amount calculation unit 25 a outputs the calculated transmission power control amount to the modulation unit 26. Thereafter, when the processing from step S104 to step S106 is executed, the channel estimation unit 31a-1 receives the training signal known in the base station apparatus 2 transmitted from the target terminal apparatus and the received digital signal. Do. The channel estimation unit 31a-1 estimates the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal (step S202). The channel estimation unit 31a-1 outputs the estimated current communication estimation CSI to the weight calculation unit 30a and the weighting combination unit 32a-1.

The weight calculation unit 30a determines the weight w ₂ (third weight) for the previous communication estimated CSI based on the previous communication estimated CSI, the current communication estimated CSI, the transmission power control amount, and the training signal. Weight w ₃ (fourth weight) for communication estimated CSI is calculated (step S 203). Specifically, the weight calculation unit 30a calculates the weight _{w 2} and the weight _{w 3} based on the following equation (7) and (8).

In the above equations (7) and (8), w ₂ represents the weight for the previous communication estimated CSI, w ₃ represents the weight for the current communication estimated CSI, α is a coefficient, and r ₂ is the predicted value of the received signal , r ₃ respectively represent the measured value of the received signal. When the calculated value of w ₃ exceeds 1, the weight calculation unit 30 a sets w ₃ = 1 and w ₂ = 0. α is an arbitrary value and may be 1. Weight calculating section 30a outputs the weight _{w 2} and the weight _{w 3} calculated for weighting combining unit 32a-1. Weighting combining unit 32a-1 is to weight the time estimated CSI previous communication using the weight _{w 2} output from the weight calculation unit 30a, weights the current communication time estimated CSI using the weight _{w 3,} the weighted CSI To generate a synthesized CSI (step S204). The weighting and combining unit 32a-1 outputs the combined CSI to the RAKE combining unit 33-1 and the interference replica signal generation unit 35-1. After that, the processes after step S110 are performed.

  In the process of step S115, when the next target terminal apparatus is determined, the channel estimation units 31a-2 to 31a-k are subtracted from the known training signal in the base station apparatus 2 transmitted from the target terminal apparatus. Input a digital signal. The channel estimation units 31a-2 to 31a-k estimate the current communication estimated CSI by calculating the correlation between the input training signal and the digital signal (step S205). The channel estimation units 31a-2 to 31a-k output the estimated current-time estimated CSI to the weight calculation unit 30a and the weight combination units 32a-2 to 32a-k.

The weight calculation unit 30a calculates the previous communication time based on the previous communication time estimation CSI, the current communication time estimation CSI output from the channel estimation units 31a-2 to 31a-k, the transmission power control amount, and the training signal. It calculates a weight _{w 3} for the weight _{w 2} and the current communication time estimated CSI for estimating CSI (step S206). Weight calculating section 30a outputs the weight _{w 2} and the weight _{w 3} calculated for weighting combining unit 32a-2~32a-k.

Weighting combining unit 32a-2~32a-k is to weight the time estimated CSI previous communication using the weight _{w 2} output from the weight calculation unit 30a, weights the current communication time estimated CSI using the weight _{w 3,} A combined CSI is generated by combining the weighted CSIs (step S207). The weighting and combining units 32a-2 to 32a-k output the combined CSI to the RAKE combining units 33-2 to 33-k and the interference replica signal generation units 35-2 to 35- (k-1). After that, the process after step S119 is performed.

According to the base station apparatus 2a configured as described above, it is possible to reduce the residual interference component generated after the interference removal process. Hereinafter, this effect will be described in detail.
The base station apparatus 2a calculates a weight for each CSI using the previous communication estimated CSI and the current communication estimated CSI. Specifically, the base station apparatus 2 calculates the difference between the predicted value and the actual measurement value of the received signal, and if the difference is small (for example, less than a threshold), determines that the time variation of CSI is small, and estimates last time communication The weight of CSI is set large, and the weight of CSI estimated this time during communication is set small. On the other hand, if the difference is large (for example, a threshold or more), it is determined that the time variation of CSI is large, the weight of the previous communication estimated CSI is small, and the current communication estimated CSI is set large. Then, the base station device 2a corrects the degradation of the CSI estimation accuracy due to interference by performing weighted combining with the previous communication estimated CSI and the current communication estimated CSI using the calculated weights. Therefore, it is possible to reduce the residual interference component generated after the interference removal process.

<Modification>
Weight calculator 30a may be configured to calculate the weight _{w 2} and the weight _{w 3} based on the following equation (9) to (12).

In the formula (9) and Formula (10), _{w 2} represents the weight for time estimated CSI previous communication, _{w 3} represents the weight for communication time estimated CSI time. In the above equations (11) and (12), k is the identification number of the terminal device 1, n _p is the identification number of the path, h ₂ , k, n _p is the estimated CSI at the time of the previous communication of the path n _p of the terminal device k , H ₂ ′, k, n _p indicate CSI obtained by adding an error due to interference to the previous communication estimated CSI, h ₃ , k, n _p indicate the current communication estimated CSI of the path n _p of the terminal device k. h ₂ ′, k, n _p are acquired as CSI estimated when signals from all the terminal devices interfere with each other temporarily based on the previous communication estimated CSI, transmission power control amount, and known training signal.
Hereinafter, the effect of the above-mentioned modification is explained in detail.
In the weighting of the previous communication estimated CSI and the current communication estimated CSI, the above equation (11) represents the error power due to interference, and the equation (12) represents the error power due to time variation. If the error power due to interference is large, it is considered that the reliability of the current communication estimated CSI that is susceptible to interference is low. On the other hand, when the error power due to the time variation is large, it is considered that the reliability of the previous communication estimated CSI that is susceptible to the time variation is low. Therefore, the base station apparatus 2a uses the above equations (9) and (10) and based on the error power calculated from the above equations (11) and (12), the weight of the higher reliability CSI is calculated. Calculate each weight to be large. Then, the base station apparatus 2a sets the calculated weights for the previous communication estimated CSI and the current communication estimated CSI, and performs weighting combining. For example, when the error power due to interference is larger than the error power due to time variation, the weight of the previous communication estimated CSI is increased. If the error power due to time variation is larger than the error power due to interference, the weight of the current communication estimated CSI is increased. The base station apparatus 2a corrects the deterioration of the CSI estimation accuracy by weighting and combining using the weights calculated as described above. Therefore, it is possible to reduce the residual interference component generated after the interference removal process.

Although each base station apparatus 20 and 20a has a plurality of demodulation order determination units 29-1 to 29-k in each of the above embodiments, one base station apparatus 20 and 20a has one demodulation order determination unit 29. May be provided. In such a configuration, the demodulation order determination unit 29 is provided between the reception radio unit 22 and the subtraction unit 36-1. When configured in this way, the demodulation order determination unit 29 determines the demodulation order of the terminal devices having the reception power higher than the threshold value, for example, in descending order of the reception powers of the terminal devices 1-1 to 1-k. For example, the demodulation order determination unit 29 randomly determines the demodulation order of the terminal apparatus having the reception power higher than the threshold. In this case, the demodulation is terminated as soon as the demodulation of all the terminals for which the demodulation order has been determined is completed.
In the above-described embodiments, when the communication interval between the terminal devices 1-1 to 1-k and the base station device 2 is intermittent, the variation due to time of the radio wave propagation path occurs in the first embodiment. It is effective to perform CSI estimation for TPC just before communication. On the other hand, when the communication between the terminal devices 1-1 to 1-k and the base station device 2 is continuous, since the variation due to time of the radio wave propagation path is small, the previous communication is performed as in the second embodiment. The form which utilizes time estimation CSI is effective.

  The terminal devices 1-1 to 1-k, the base station device 2 and the base station device 2a in the embodiment described above may be realized by a computer. In that case, a program for realizing this function may be recorded in a computer readable recording medium, and the program recorded in the recording medium may be read and executed by a computer system. Here, the “computer system” includes an OS and hardware such as peripheral devices. The term "computer-readable recording medium" refers to a storage medium such as a flexible disk, a magneto-optical disk, a ROM, a portable medium such as a ROM or a CD-ROM, or a hard disk built in a computer system. Furthermore, “computer-readable recording medium” dynamically holds a program for a short time, like a communication line in the case of transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include one that holds a program for a certain period of time, such as volatile memory in a computer system that becomes a server or a client in that case. Further, the program may be for realizing a part of the functions described above, or may be realized in combination with the program already recorded in the computer system. It may be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within the scope of the present invention.

1-1 to 1-k Terminal unit 2, 2a Base station apparatus 21 Antenna 22, 22a Reception radio unit 23 Reception processing determination unit 24 Pre-channel estimation unit 25, 25a Transmission power control amount calculation unit, 26: modulation unit, 27: spreading unit, 28: transmission radio unit, 29-1 to 29-k, demodulation order determination unit, 30, 30a: weight calculation unit, 31-1 to 31 -K, 31a-1 to 31a-k ... channel estimation unit, 32-1 to 32-k, 32a-1 to 32a-k ... weighting combining unit, 33-1 to 33-k ... RAKE combining unit, 34-1 -34-k, 34a-1 to 34a-k ... demodulation unit, 35-1 to 35-(k-1) ... interference replica signal generation unit, 36-1 to 36-(k-1) ... subtraction unit

Claims (8)

A wireless communication apparatus that operates as the receiving station apparatus in a wireless communication system in which interference is reduced by successive interference cancellers at the time of demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus,
A first channel estimation unit configured to estimate in advance first channel state information between the own apparatus and each of the transmission apparatuses;
A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on the first channel state information estimated in advance;
A second channel estimation unit configured to estimate second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmitters;
Predicted value of the reception signal obtained from said first channel state information and training signal before Symbol transmission power control amount and the already known, and based on the measured value of the received signal, to said first channel state information A weight calculator configured to calculate a first weight and a second weight for the second channel state information;
The first channel state information and the second channel state information based on the first channel state information, the second channel state information, the first weight, and the second weight. Weighting combining section for weighting and combining
Wireless communication device comprising: A wireless communication apparatus that operates as the receiving station apparatus in a wireless communication system in which interference is reduced by successive interference cancellers at the time of demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus,
A first channel estimation unit configured to estimate in advance first channel state information between the own apparatus and each of the transmission apparatuses;
A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on the first channel state information estimated in advance;
A second channel estimation unit configured to estimate second channel state information at the time of communication from reception signals simultaneously received from the plurality of transmitters;
Before SL first channel state information, the first obtained from the channel state information and the transmission power control amount and the known training signal, the first channel state information plus error due to interference on the channel state information distribution, and pre-SL based on the second channel state information, a weight calculator for calculating a second weight to the first weight and the second channel state information for the first channel state information,
The first channel state information and the second channel state information based on the first channel state information, the second channel state information, the first weight, and the second weight. Weighting combining section for weighting and combining
Wireless communication device comprising a. A wireless communication apparatus that operates as the receiving station apparatus in a wireless communication system in which interference is reduced by successive interference cancellers at the time of demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus,
A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices;
A fourth channel estimation unit configured to estimate fourth channel state information at the time of current communication from reception signals simultaneously received from the plurality of transmitters;
Predicted value of the reception signal obtained from the training signal of the third channel state information and the previous SL transmission power control amount and the already known, and based on the measured value of the received signal, to said third channel state information A weight calculator configured to calculate a third weight and a fourth weight for the fourth channel state information;
The third channel state information and the fourth channel state information based on the third channel state information, the fourth channel state information, the third weight, and the fourth weight Weighting combining section for weighting and combining
Wireless communication device comprising: A wireless communication apparatus that operates as the receiving station apparatus in a wireless communication system in which interference is reduced by successive interference cancellers at the time of demodulation of transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus,
A transmission power control amount calculation unit that calculates a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices;
A fourth channel estimation unit configured to estimate fourth channel state information at the time of current communication from reception signals simultaneously received from the plurality of transmitters;
Before Symbol third channel state information, the third channel state information and the transmission power control amount and calculated from the known training signal, the third channel state information plus error due to interference on the channel state information distribution, and pre-SL based on the fourth channel state information, a weight calculation unit that calculates a fourth weight to the third weight and the fourth channel state information for said third channel state information,
The third channel state information and the fourth channel state information based on the third channel state information, the fourth channel state information, the third weight, and the fourth weight Weighting combining section for weighting and combining
Wireless communication device comprising a. A method for reducing interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system, wherein interference is reduced by successive interference cancelers when transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus are demodulated,
A first channel estimation step of pre-estimating first channel state information between its own device and each of said transmitting devices;
A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices based on the first channel state information estimated in advance;
A second channel estimation step of estimating second channel state information at the time of communication from received signals simultaneously received from the plurality of transmitters;
Predicted value of the reception signal obtained from said first channel state information and training signal before Symbol transmission power control amount and the already known, and based on the measured value of the received signal, to said first channel state information Calculating a first weight and a second weight for the second channel state information;
The first channel state information and the second channel state information based on the first channel state information, the second channel state information, the first weight, and the second weight. Weighting combining step of weighting and combining
Interference reduction method. A method for reducing interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system, wherein interference is reduced by successive interference cancelers when transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus are demodulated,
A first channel estimation step of pre-estimating first channel state information between its own device and each of said transmitting devices;
A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices based on the first channel state information estimated in advance;
A second channel estimation step of estimating second channel state information at the time of communication from received signals simultaneously received from the plurality of transmitters;
Channel state information obtained by adding an error due to interference to the first channel state information obtained from the first channel state information, the first channel state information, the transmission power control amount, and a known training signal; based on the second channel state information, and weight calculation step of calculating a second weight to the first weight and the second channel state information for the first channel state information,
The first channel state information and the second channel state information based on the first channel state information, the second channel state information, the first weight, and the second weight. Weighting combining step of weighting and combining
Interference reduction method. A method for reducing interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system, wherein interference is reduced by successive interference cancelers when transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus are demodulated,
A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices;
A fourth channel estimation step of estimating fourth channel state information at the time of current communication from reception signals simultaneously received from the plurality of transmitters;
Predicted value of the reception signal obtained from the training signal of the third channel state information and the previous SL transmission power control amount and the already known, and based on the measured value of the received signal, to said third channel state information Calculating a third weight and a fourth weight for the fourth channel state information;
The third channel state information and the fourth channel state information based on the third channel state information, the fourth channel state information, the fourth weight, and the fourth weight Weighting combining step of weighting and combining
Interference reduction method. A method for reducing interference in a wireless communication apparatus operating as the receiving station apparatus in a wireless communication system, wherein interference is reduced by successive interference cancelers when transmission signals from a plurality of transmitting apparatuses simultaneously received in the receiving station apparatus are demodulated,
A transmission power control amount calculating step of calculating a transmission power control amount of each of the transmission devices based on third channel state information between the own device estimated during the previous communication and each of the transmission devices;
A fourth channel estimation step of estimating fourth channel state information at the time of current communication from reception signals simultaneously received from the plurality of transmitters;
Channel state information obtained by adding an error due to interference to the third channel state information obtained from the third channel state information, the third channel state information, the transmission power control amount, and a known training signal; based on the fourth channel state information, and weight calculation step of calculating a fourth weight to the third weight and the fourth channel state information for said third channel state information,
The third channel state information and the fourth channel state information based on the third channel state information, the fourth channel state information, the fourth weight, and the fourth weight Weighting combining step of weighting and combining
Interference reduction method.

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