JP2014236489A - Radio communication system, radio communication device, radio communication method, and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an interference signal even if the power of the interference signal cannot be learned in advance.SOLUTION: A radio communication system comprises: receiving means that receives, by means of a plurality of antennas, a transmission signal in which different transmission power is allocated every multiple bands into which a frequency band used in radio communication is divided; frequency band division means that divides a reception signal received by the receiving means into signals in the multiple bands; interference detection means that detects the presence or absence of an interference signal in the reception signal and reception power on the basis of the reception power of a signal every multiple bands divided by the frequency band division means and transmission power allocation at multiple frequencies; weight selection means that selects weight applied to each of the bands on the basis of the detection result of the interference detection means; and signal combination means that combines the reception signals corresponding to the respective antennas into one signal by use of the weight selected by the weight selection means.

Description

  The present invention relates to a wireless communication system, a wireless communication apparatus, a wireless communication method, and a receiving method to which an adaptive array antenna technology is applied.

  In order to cope with various large-capacity services accompanying the recent spread of optical access and the like, it is required to improve the transmission speed of wireless communication. Since the occupied frequency band is proportional to the transmission speed, this can be realized by expanding the frequency band. However, since the actual frequency resources are limited, there is a limit to the expansion of the frequency band. In addition, various wireless access systems such as WiFi (registered trademark), WiMAX (registered trademark), and LTE (registered trademark) are widespread, and in particular, frequency resources in the microwave band allocated to these systems. Is in a tight situation.

  Therefore, in order to improve the transmission capacity in a limited frequency resource environment, a transmission / reception station is provided with a plurality of antennas, and spatial division multiplexing transmission by applying MIMO or multi-user MIMO (MU-MIMO) technology is effective. is there. Extending this method, arranging centralized control stations that share channel information, transmission signals, and reception signals among a plurality of base stations, or handle them all at once, and apply (MU-) MIMO technology to make them adjacent Base station cooperation that can eliminate interference between base stations is also being studied. As described above, it is possible to cope with interference by grasping information about interference signals in advance between the same systems.

  Further, in order to expand the frequency bandwidth and further improve the transmission capacity, it is necessary to share frequency resources between a plurality of systems and allow the coexistence of the plurality of systems. In order to cope with unknown co-channel interference between different systems, an adaptive array antenna technique as shown in Non-Patent Document 1 is effective. There are various algorithms in adaptive array antenna technology. For example, the minimum mean square error (MMSE) method using known information such as a training signal shared between the transmitting and receiving stations, or a blind algorithm that does not require known information is power. There are inversion (Power Inversion; PI) and constant envelope algorithm (CMA). In packet-based wireless communication, MMSE is effective because a training signal is added for timing detection, but in a situation where it is impossible to predict at what timing and at what level interference will arrive. It is considered that PI and CMA that do not require a training signal are effective.

  FIG. 13 is a block diagram illustrating a configuration example of a wireless communication system. The figure shows a wireless communication system comprising a wireless communication device 120a and a wireless communication device 120b. Hereinafter, one or both of the wireless communication device 120a and the wireless communication device 120b are collectively referred to as the wireless communication device 120. The wireless communication device 120 includes a data input / output unit 121, a MAC layer processing unit 122, a communication control unit 123, a reception signal processing unit 124, a transmission signal processing unit 126, a switch (SW) 127, an antenna 128, It has. Note that the configuration in FIG. 13 is a configuration in which the wireless communication apparatus 120 includes a plurality of antennas 128.

  The data input / output unit 121 inputs data to be transmitted to the destination station. The data input / output unit 121 outputs data input from the MAC layer processing unit 122 to the user. The MAC layer processing unit 122 performs processing related to the MAC layer on the data input from the reception signal processing unit 124 and outputs the processed data to the data input / output unit 121. Further, the MAC layer processing unit 122 performs processing related to the MAC layer on the data input from the data input / output unit 121 and outputs the processed data to the transmission signal processing unit 126.

  The communication control unit 123 controls transmission / reception at the antenna 128, that is, control related to switching of transmission / reception at the switch 127, operation timing control at the reception signal processing unit 124 and transmission signal processing unit 126, and a communication partner. Control related to overall communication such as processing for selecting another wireless communication device 120 and timing control for the entire wireless communication system is performed.

  The reception signal processing unit 124 performs reception signal processing on the reception signal received by the antenna 128. The transmission signal processing unit 126 performs transmission signal processing on the transmission data input from the MAC layer processing unit 122 and transmits the transmission data from the antenna 128. The switch 127 connects the antenna 128 and the transmission signal processing unit 126 at the time of transmission and connects the antenna 128 and the reception signal processing unit 124 at the time of reception according to an instruction from the communication control unit 123.

A transmission operation in wireless communication apparatus 120 will be described.
When data to be transmitted to the destination station is input from the outside to the data input / output unit 121, the MAC layer processing unit 122 converts the data input to the data input / output unit 121 into data to be transmitted / received on a wireless line. Convert. The MAC layer processing unit 122 further outputs transmission data obtained by performing processing such as adding MAC layer header information to the transmission signal processing unit 126.

  The transmission signal processing unit 126 performs modulation processing on the transmission data output from the MAC layer processing unit 122. The transmission signal processing unit 126 transmits the transmission signal obtained by the modulation processing from the antenna 128 via the switch 127.

Next, a reception operation in the wireless communication device 120 will be described.
When signals transmitted from the destination addressed to the device itself are received by the plurality of antennas 128, the received signal (reception signal) is input to the reception signal processing unit 124 via the switch 127. The reception signal processing unit 124 performs array processing on the reception signals received by each of the plurality of antennas 128, and calculates reception weights for acquiring a desired signal from the reception signals. The reception signal processing unit 124 acquires a desired signal from the reception signal using the calculated reception weight, and performs various signal processing such as demodulation and decoding on the acquired desired signal to acquire data. The reception signal processing unit 124 outputs the acquired data to the MAC layer processing unit 122.

  The MAC layer processing unit 122 performs processing related to the MAC layer on the data output from the reception signal processing unit 124 (for example, the input / output data to the data input / output unit 121 and the data transmitted / received on the wireless line). Conversion, termination of MAC layer header information, etc.). The MAC layer processing unit 122 causes the data subjected to the processing related to the MAC layer to be output to an output device such as an external display or an external network via the data input / output unit 121.

  Although not particularly specified, the antenna 128 performs D / A (Digital / Analog) conversion and radio frequency on the signal subjected to baseband modulation processing in the transmission signal processing unit 126 during transmission. The signal is transmitted after being subjected to up-conversion to a signal and filtering processing for removing frequency components outside the band. Further, the reverse processing is performed at the time of reception, and then the baseband reception signal is input to the reception signal processing unit 124.

  FIG. 14 is a block diagram illustrating a configuration example of the transmission signal processing unit 126 when the wireless communication apparatus 120 performs single carrier communication. The transmission signal processing unit 126 includes a modulation unit 131. The modulation unit 131 performs symbol mapping processing after performing error correction coding processing on the data output from the MAC layer processing unit 122. For example, a carrier wave having a predetermined bandwidth is modulated based on information on the IQ plane of each symbol. Moreover, the modulation | alteration part 131 inserts a guard interval as needed for the purpose of giving a transmission signal periodicity for a FFT (Fast Fourier Transform; Fast Fourier Transform) process.

  FIG. 15 is a block diagram illustrating a configuration example of the transmission signal processing unit 126 when the wireless communication apparatus 120 performs communication using the OFDM modulation scheme. The transmission signal processing unit 126 includes a modulation unit 131, a serial / parallel conversion unit 132, and an IDFT (Inverse Discrete Fourier Transform) unit 133. The modulation unit 131 performs symbol mapping processing after performing error correction coding processing on the data output from the MAC layer processing unit 122.

  The serial / parallel converter 132 performs serial / parallel conversion on the symbols mapped by the modulator 131, and outputs a plurality of obtained symbol strings to the IDFT unit 133. The IDFT unit 133 performs IDFT on the plurality of symbol sequences output from the serial / parallel conversion unit 132, converts the signal in the frequency domain into a signal in the time domain, and outputs the signal to the antenna 128. In addition, the transmission signal processing unit 126 performs insertion of a guard interval, waveform shaping processing between OFDM symbols, and the like as necessary, and outputs an electric signal to be transmitted to the antenna 128.

  FIG. 16 is a block diagram illustrating a configuration example of the reception signal processing unit 124 when the wireless communication apparatus 120 performs single carrier communication. In the figure, a configuration in the case where the wireless communication apparatus 120 includes two antennas 128 is shown. The reception signal processing unit 124 includes an adaptive array processing unit 152, a multiplier 153 provided corresponding to the antenna 128, an adder 154, and a demodulation unit 156. Two received signals (received signal 1 and received signal 2) input from the antenna 128 to the received signal processing unit 124 are input to an adaptive array processing unit 152 and a multiplier 153 provided for each received signal. Is done.

  The adaptive array processing unit 152 uses a predetermined algorithm (such as PI or CMA) to weight the interference signal included in the reception signal 1 and the reception signal 2 based on the input reception signal 1 and the reception signal 2. calculate. The adaptive array processing unit 152 inputs the calculated weight to the multiplier 153. Multiplier 153 multiplies input reception signal 1 by a weight and outputs the multiplication result to adder 154. The adder 154 adds the multiplication results output from the two multipliers 153 and inputs the addition results to the demodulation unit 156. In this way, one system of signals in which interference signals are suppressed is obtained by array processing including weight multiplication and synthesis.

  Demodulation section 156 extracts symbols demapped by orthogonal demodulation processing from the received signals subjected to array processing, and performs error correction decoding processing on the extracted symbols to obtain a final data series. . Demodulation section 156 outputs the acquired data series to MAC layer processing section 122.

  Next, an operation when radio communication apparatus 120 performs communication using a multicarrier transmission scheme will be described. As an example, description will be made using an OFDM or OFDMA modulation scheme. FIG. 17 is a block diagram illustrating a configuration of the reception signal processing unit 124 when the wireless communication apparatus 120 performs communication using the OFDM modulation scheme. In the same figure, as in the configuration example shown in FIG. 16, a configuration in the case where the wireless communication apparatus 120 includes two antennas 128 is shown. The received signal processing unit 124 includes a DFT unit 151, a plurality of adaptive array processing units 152, a plurality of multipliers 153, a plurality of adders 154, a parallel / serial conversion unit 155, and a demodulation unit 156. ing. The DFT unit 151 is provided corresponding to the antenna 128. An adaptive array processor 152 and an adder 154 are provided for each subcarrier. Multiplier 153 is provided for each subcarrier signal output from DFT section 151.

  The DFT unit 151 receives a reception signal (reception signal 1 or reception signal 2) received by the corresponding antenna 128, performs DFT on the input reception signal, and converts a time domain signal into a frequency domain signal. The signal of each subcarrier is acquired by conversion. The DFT unit 151 outputs the acquired signal of each subcarrier to the adaptive array processing unit 152 and the multiplier 153.

  Adaptive array processing section 152 receives the corresponding subcarrier signal from each DFT section 151. Based on the corresponding subcarrier signal in received signal 1 and the corresponding subcarrier signal in received signal 2, adaptive array processing section 152 sets a weight for suppressing the interference signal included in each signal. It is calculated by the algorithm (PI or CMA).

  Each of the multipliers 153 is provided for each subcarrier signal output from each DFT section 151, and the corresponding subcarrier signal and the weight calculated by the corresponding subcarrier adaptive array processing section 152 are provided. Entered. Multiplier 153 multiplies the input subcarrier signal and the weight, and outputs the multiplication result to corresponding subcarrier adder 154. Each adder 154 adds the multiplication results output from the corresponding subcarrier multiplier 153, and inputs the addition result to the parallel / serial converter 155. In this way, a signal of each subcarrier in which an interference signal is suppressed is obtained by array processing including multiplication and combination of weights.

  The parallel / serial converter 155 inputs the signal of each subcarrier that has been subjected to the array processing from each adder 154, performs parallel / serial conversion on the input signal of each subcarrier, The signal is acquired, and the acquired one system signal is output to the demodulator 156. Demodulation section 156 extracts symbols demapped by orthogonal demodulation processing from one system of signals output from parallel / serial conversion section 155, and finally performs error correction decoding processing on the extracted symbols. The correct data series. Demodulation section 156 outputs the acquired data series to MAC layer processing section 122.

  Here, the configuration for performing the array processing for each subcarrier has been described using the case where the adaptive array processing unit 152, the multiplier 153, and the adder 154 are provided for each subcarrier. However, the present processing is not limited to this example. It can be implemented. For example, the received signal processing unit 124 includes the adaptive array processing unit 152, the multiplier 153, and the adder 154 one by one or a number smaller than the number of subcarriers, and performs array processing for each subcarrier in a time division manner. It does not matter as a configuration. Also, a plurality of subcarriers may be combined into one subchannel, and the above array processing may be performed on a subchannel basis. In this way, array processing in OFDM (multi-carrier transmission) can be realized using any method.

  In the example of FIGS. 16 and 17, the case where there are two reception antennas has been described as an example, but the number of antennas may be three or more. In general, when the number of antennas is N, N-1 interference waves can be suppressed by applying an adaptive array.

  The wireless communication apparatus 120 configured as described above can perform communication while suppressing an incoming interference signal without using a known signal such as a training signal by using an algorithm of PI or CMA.

Nobuyoshi Kikuma, “Adaptive Antenna Technology”, Ohm, October 2003

  However, these adaptive array algorithms have the feature that PI works when the Signal to Interference power Ratio (SIR) is less than 0, while CMA has a feature when SIR is greater than 0. It has functional features and their operating area is limited. Also in MMSE, when the SIR is small, a sufficient interference suppression effect cannot be obtained. For this reason, there has been a problem that communication may not be possible without sufficiently suppressing the interference signal in a situation where the power of the interference signal changes or when the power of the interference signal cannot be predicted.

  In view of the above circumstances, an object of the present invention is to provide a wireless communication method, a wireless communication device, a wireless communication method, and a receiving method capable of suppressing an interference signal even when the power of the interference signal cannot be grasped in advance. It is said.

  One embodiment of the present invention is a wireless communication method in which a first wireless communication device and a second wireless communication device perform wireless communication, and the first wireless communication device includes a plurality of frequency bands used for wireless communication. Transmitting means for transmitting a signal to which different transmission power is assigned for each band of the second wireless communication device, wherein the second wireless communication device receives a signal transmitted by the transmitting means using a plurality of antennas, and Frequency band dividing means for dividing the received signal received by the receiving means into signals of the plurality of bands, received power of the signals for each of the plurality of bands divided by the frequency band dividing means, and the transmitting means for the plurality of bands Interference detection means for detecting presence / absence of an interference signal in the received signal and reception power based on the transmission power allocated to each of the received signals, and the band based on the detection result of the interference detection means. Weight selection means for selecting a weight to be applied to each, and signal combining means for combining the received signal corresponding to each of the antennas into one signal using the weight selected by the weight selection means. This is a featured wireless communication system.

In addition, according to one aspect of the present invention, in the above wireless communication system, the interference detection unit includes a difference in received power between the plurality of bands in the received signal and a difference between the plurality of bands assigned by the transmission unit. A reception power of an interference signal is detected based on a difference in transmission power, and the weight selection unit is configured to select one of the weights calculated based on a different adaptive array algorithm based on a detection result of the interference detection unit. It is characterized by selecting a weight.
Further, according to an aspect of the present invention, in the above wireless communication system, the second wireless communication apparatus assigns transmission power in the plurality of bands based on a detection result of the interference detection unit. Feedback means for instructing the communication apparatus is further provided, wherein the transmission means transmits a transmission signal with transmission power allocation instructed by the feedback means.

  Another embodiment of the present invention is a reception unit that receives a transmission signal in which different transmission powers are allocated to a plurality of bands obtained by dividing a frequency band used for wireless communication, using a plurality of antennas; and the reception unit receives Based on frequency band dividing means for dividing the received signal into signals of the plurality of bands, reception power of the signals for each of the plurality of bands divided by the frequency band dividing means, and allocation of transmission power in the plurality of bands Interference detection means for detecting presence / absence of interference signals and reception power in the received signal, weight selection means for selecting weights to be applied to each of the bands based on detection results of the interference detection means, and weight selection Signal combining means for combining the received signals corresponding to the antennas into one signal using the weight selected by the means; Is a wireless communication apparatus comprising: a.

  One embodiment of the present invention is a wireless communication method in a wireless communication system including a first wireless communication device and a second wireless communication device, and the first wireless communication device uses a frequency band for wireless communication. A transmission step of transmitting a signal assigned different transmission power for each of a plurality of divided bands, and a reception step of receiving the signal transmitted in the transmission step using a plurality of antennas by the second wireless communication apparatus A frequency band dividing step of dividing the received signal received in the receiving step into the signals of the plurality of bands, a received power of the signal for each of the plurality of bands divided in the frequency band dividing step, and in the transmitting step, Based on the transmission power assigned to each of the plurality of bands, the presence / absence of an interference signal in the received signal and the received power are detected. Corresponding to each of the antennas using a weight selection step for selecting a weight to be applied in each band based on a detection result in the interference detection step, and a weight selected in the weight selection step. And a signal combining step of combining the received signal into a single signal.

  One embodiment of the present invention is a reception method in a wireless communication apparatus, which receives a transmission signal in which different transmission powers are assigned to a plurality of bands into which a frequency band used for wireless communication is divided, using a plurality of antennas. Receiving step, a frequency band dividing step for dividing the received signal received in the receiving step into the signals of the plurality of bands, a received power of the signal for each of the plurality of bands divided in the frequency band dividing step, and the plurality of An interference detection step for detecting presence / absence of an interference signal and reception power in the received signal based on transmission power allocation in the band, and a weight to be applied in each band based on a detection result of the interference detection step. Weight selection step to be selected and the weight selected in the weight selection step Used is a receiving method characterized by having the signal combining step of combining into a single signal the received signal corresponding to each of the antennas.

  According to the present invention, the interference detection means detects the presence / absence of the interference signal and the reception power based on the difference between the transmission power between the bands in the transmission signal and the difference between the reception power between the bands in the reception signal. The weight for suppressing the signal can be selected, and the interference signal can be suppressed even when the power of the interference signal cannot be grasped in advance.

It is a figure which shows an example of the received signal in the radio | wireless communication apparatus which concerns on this invention. It is a block diagram which shows the structural example of the transmission signal process part 126 in 1st Embodiment which concerns on this invention. It is a block diagram which shows the structural example of the received signal process part 124 in the embodiment. 4 is a flowchart showing a transmission process performed by the wireless communication apparatus 120 in the embodiment. 6 is a flowchart illustrating a reception process performed by the wireless communication device 120 according to the embodiment. It is a figure which shows an example of the pattern table which shows the power density allocated to each subchannel in 2nd Embodiment. It is a sequence diagram which shows the operation example of the radio | wireless communication apparatus 120 (120a, 120b) in the radio | wireless communications system of the embodiment. It is a block diagram which shows the structural example of the transmission signal process part 126 in 3rd Embodiment. It is a block diagram which shows the structure of the received signal processing part 124 in the embodiment. 6 is a flowchart for performing transmission processing performed by the wireless communication apparatus 120 according to the embodiment. 6 is a flowchart illustrating a reception process performed by the wireless communication device 120 according to the embodiment. It is a sequence diagram which shows operation | movement of the radio | wireless communication apparatus 120 (120a, 120b) in the radio | wireless communications system of the embodiment. It is a block diagram which shows the structural example of a radio | wireless communications system. It is a block diagram which shows the structural example of the transmission signal process part 126 when the radio | wireless communication apparatus 120 performs single carrier communication. FIG. 3 is a block diagram illustrating a configuration example of a transmission signal processing unit 126 when the wireless communication device 120 performs communication using the OFDM modulation scheme. It is a block diagram which shows the structural example of the received signal process part 124 when the radio | wireless communication apparatus 120 performs single carrier communication. It is a block diagram which shows the structure of the received signal process part 124 when the radio | wireless communication apparatus 120 communicates using an OFDM modulation system.

  Hereinafter, a wireless communication system, a wireless communication apparatus, and a wireless communication method according to embodiments of the present invention will be described with reference to the drawings.

<Outline of the present invention>
In the radio communication system, radio communication apparatus, radio communication method, and reception method according to the present invention, the frequency band used in communication to which the adaptive array antenna technology is applied is divided into a plurality of predetermined bands, and the radio on the transmission side The communication device transmits a signal with a difference in transmission power (or transmission power density) in each band. The wireless communication device on the reception side determines the presence / absence of the interference signal and the power of the interference signal based on the reception power of each band in the received signal and the transmission power of each band when transmitted on the transmission side.

  FIG. 1 is a diagram illustrating an example of a received signal in a wireless communication apparatus according to the present invention. Here, a case where a frequency band used in communication is divided into two bands will be described. In the figure, the horizontal axis indicates the frequency, and the vertical axis indicates the power density. A power difference is provided between a low frequency band (hereinafter referred to as a low frequency band) and a high frequency band (hereinafter referred to as a high frequency band) among frequency bands used in communication. In the example shown in the figure, the transmission power in the low frequency band is set lower than the transmission power in the high frequency band. Information indicating the power ratio between the low frequency band and the high frequency band at this time is shared in advance between the transmission side and the reception side.

  When an interference signal as shown in FIG. 1A is superimposed on a desired signal (a transmission signal transmitted by the transmission-side wireless communication device) in the reception signal received by the reception-side wireless communication device, the reception signal The power ratio between the low frequency band and the high frequency band in is different from the power ratio between the low frequency band and the high frequency band in the transmission signal. In this case, the radio communication device on the reception side determines that the reception power of the interference signal included in the reception signal is higher than the reception power of the low frequency band in the transmission signal and lower than the reception power of the transmission signal of the high frequency band be able to.

  In addition, when the interference signal as shown in FIG. 1B is superimposed on the desired signal in the reception signal received by the reception-side wireless communication device, the power of the low frequency band and the high frequency band in the reception signal There will be almost no difference. That is, the reception power of the interference signal is dominant in the reception signal, and the transmission signal is buried in the interference signal. In this case, the radio communication device on the reception side can determine that the power of the interference signal included in the reception signal is equal to or higher than the reception power in the high frequency band of the transmission signal.

  When an interference signal as shown in FIG. 1C is superimposed on the desired signal in the reception signal received by the reception-side wireless communication device, the power of the low frequency band and the high frequency band in the reception signal The ratio will be approximately equal to the power ratio in the transmitted signal. In this case, the radio communication device on the reception side can determine that the reception power of the interference signal included in the reception signal is equal to or lower than the reception power of the low frequency band in the transmission signal.

  In this way, a difference in power density on the frequency axis in the reception signal received by the reception-side wireless communication apparatus is transmitted with a difference in power density on the frequency axis of the transmission signal transmitted by the transmission-side wireless communication apparatus. (Or ratio) and the difference (or ratio) in the transmitted signal. Thereby, the relationship between the reception power of the interference signal included in the reception signal and the reception power of the transmission signal can be detected. Thereby, in the radio communication apparatus on the receiving side, it is possible to determine which one of the blind algorithm PI and CMA is used to suppress the interference signal using the weight calculated by the algorithm. As a result, even in a situation where the power of the interference signal cannot be grasped in advance, it is possible to suppress the interference signal by selecting a blind algorithm effective for suppressing the interference signal. At this time, when viewed for each band, the difference between the received power of the interference signal and the received power of the desired signal is small (or SIR≈0, for example, the high frequency band in FIG. 1B and the one in FIG. 1C). In the case of the low frequency band), the difference (or ratio) between the received power of the interference signal and the received power of the desired signal is equal to or higher than a predetermined value (the low frequency band in FIG. 1B and FIG. The weight calculated by applying the blind algorithm in the high frequency band (C) is used. As a result, the weight can be calculated outside the area where PI or CMA cannot be applied.

  Although the case where the frequency band used in communication is divided into two has been described here, the presence / absence of an interference signal and the reception power of the interference signal included in the reception signal are determined by dividing the frequency band into three or more bands. May be. Estimate the difference between the received power of the interference signal and the received signal of the desired signal by comparing the difference (ratio) of the transmission power between multiple bands with the difference (ratio) of the received power between the bands in the received signal can do. When there is almost no difference between the received power of the interference signal and the desired signal in a certain band (SIR≈0), the received power of the desired signal is higher than the received power of the interference signal (SIR> 0). A weight using CMA or a weight using PI in a band where the received power of a desired signal is lower than the received power of an interference signal (SIR <0) is selected. Hereinafter, a specific configuration of the wireless communication device will be described.

<First Embodiment>
A wireless communication device in a wireless communication system (wireless communication method) to which the adaptive array antenna technology in the first embodiment is applied has the same functional units as the wireless communication device 120 shown in FIG. In the wireless communication device 120 according to the present embodiment, the configurations of the transmission signal processing unit 126 and the reception signal processing unit 124 are different from the configuration illustrated in FIG. Hereinafter, configurations of the transmission signal processing unit 126 and the reception signal processing unit 124 in the present embodiment will be described.

  FIG. 2 is a block diagram showing a configuration example of the transmission signal processing unit 126 in the first embodiment according to the present invention. The configuration of the transmission signal processing unit 126 shown in the figure is a configuration when the wireless communication apparatus 120 performs single carrier communication. The transmission signal processing unit 126 includes a modulation unit 131, filter units 141-1 to 141-k, power allocation units 142-1 to 142-k, and a signal synthesis unit 143. The filter units 141-1 to 141-k and the power allocation units 142-1 to 142-k are bands (subchannels) obtained by dividing the frequency band used for communication by the wireless communication apparatus 120 in this embodiment into k (k ≧ 2). ) It is provided corresponding to each.

  The modulation unit 131 performs error correction coding processing on transmission data output from the MAC layer processing unit 122 and then performs symbol mapping processing to modulate a carrier wave having a predetermined bandwidth. The modulation unit 131 outputs the transmission signal obtained by the modulation to each filter unit 141-1 to 141-k.

  Each of the filter units 141-1 to 141-k is configured using a band pass filter that passes the signal component of the subchannel associated with itself. The filter units 141-1 to 141-k include, in the transmission signal output from the modulation unit 131, the signal of the component in the subchannel associated with itself, the power allocation unit associated with the subchannel. Input to 142-1 to 142-k.

  The power allocation units 142-1 to 142-k allocate predetermined power for each subchannel to the signals of each subchannel input from the filter units 141-1 to 141-k. Specifically, the power allocation units 142-1 to 142-k amplify or attenuate the input signals of the subchannels so that the power is allocated in advance. The power allocation units 142-1 to 142-k convert the power of each subchannel signal to the allocated power and output it to the signal synthesis unit 143. The power allocated to each of the k subchannels is shared between the radio communication device 120 on the transmission side and the radio communication device 120 on the reception side. Note that power may be allocated to each subchannel so that the total power allocated to each of the k subchannels is constant.

  The signal combining unit 143 combines the signals of the subchannels output from the power allocating units 142-1 to 142-k into one signal, outputs the combined signal to the antenna 128 as a transmission signal, and transmits the wireless signal of the destination station. It transmits toward the communication apparatus 120.

  FIG. 3 is a block diagram illustrating a configuration example of the reception signal processing unit 124 in the present embodiment. The configuration of the received signal processing unit 124 shown in the figure is a configuration when the wireless communication apparatus 120 includes two antennas 128 and performs single carrier communication. The received signal processing unit 124 includes filter units 161-1-1 to 161-1-k, filter units 161-2-1 to 161-2-k, adaptive array processing units 152-1 to 152-k, Multipliers 153-1 to 153-1-k, multipliers 153-1 to 153-2-k, adders 154-1 to 154-k, a signal synthesis unit 164, and a demodulation unit 156 And an interference detection unit 162 and an array processing control unit 163.

  Filter units 161-1-1 to 161-1-k, filter units 161-2-1-161-2-k, adaptive array processing units 152-1-152-k, and multiplier 153-1-1 -153-1-k, multipliers 153-1 to 153-2-k, and adders 154-1 to 154-k are subchannels obtained by dividing a frequency band used in communication into k. Correspondingly provided.

  The filter units 161-1-1 to 161-1-k and the filter units 161-2-1 to 161-2-k are provided corresponding to the two antennas 128 provided in the wireless communication device 120. ing. The received signal 1 received by one of the two antennas 128 is input to each of the filter units 161-1-1 to 161-1-k, and the received signal 2 received by the other antenna 128 is filtered. Are input to the sections 161-2-1 to 161-2-k.

  Similarly to the filter units 141-1 to 141-k included in the transmission signal processing unit 126, the filter units 161-1 to 161-1-k pass a band of subchannel signal components associated in advance. It is configured using a pass filter. The filter units 161-1-1 to 161-1-1 k receive the component signal in the subchannel associated with the received signal 1, and the multiplier associated with the subchannel. Output to 153-1-1 to 153-1-k and the interference detection unit 162.

  Similarly to the filter units 161-1-1 to 161-1-k, the filter units 161-2-1 to 161-2-k are subchannels associated with themselves among the input received signals 2. Are output to the multipliers 153-1 to 153-2-k and the interference detection unit 162 associated with the subchannel.

  The interference detection unit 162 is assigned to the power of each subchannel signal input from the filter units 161-1-1 to 161-1-k and each subchannel of the transmission signal in the transmission-side radio communication apparatus 120. Based on the power, the presence / absence of an interference signal in the received signal 1 and its power are determined. Further, the interference detection unit 162 assigns the power of each subchannel signal input from the filter units 161-2-1 to 16-1-k and the subchannel of the transmission signal in the radio communication device 120 on the transmission side. Based on the received power, the presence / absence of an interference signal in the received signal 2 and its power are determined. The interference detection unit 162 outputs the detection result of the interference signal to the array processing control unit 163.

  Each of the adaptive array processing units 152-1 to 152-k converts the subchannel signals associated with the adaptive array processing units 152-1 to 152-k into the filter units 161-1 to 161-1-k and the filter units 161-2-1 to 161. Input from -2-k. The adaptive array processing units 152-1 to 152-k perform the blind type algorithm corresponding to the power allocated on the transmitting side for the subchannels associated with the adaptive channel processing units 152-1 to 152-k. Applying to the signal, the weights for the received signal 1 and the received signal 2 are calculated. The adaptive array processing units 152-1 to 152-k output the calculated weights to the array processing control unit 163.

  For example, the blind algorithm used in the adaptive array processing units 152-1 to 152-k applies PI when the power allocated to the corresponding subchannel on the transmission side is less than a predetermined power, Apply CMA in some cases. This predetermined power is determined in advance based on a difference or ratio of power allocated to each subchannel on the transmission side.

  Which weight is used by array processing control section 163 based on the weight calculated in each adaptive array processing section 152-1 to 152-k and the detection result of the interference signal output from interference detecting section 162? Select. For example, when there is an interference signal as shown in FIG. 1A, the array processing control unit 163 has the largest difference (or ratio) from the power of the interference signal in the received signal among the subchannels. The weight calculated by the adaptive array processing unit 152 corresponding to the subchannel of the large desired signal is selected.

  In addition, when an interference signal as shown in FIG. 1B exists, the array processing control unit 163 applies PI among the weights calculated by the adaptive array processing units 152-1 to 152-k. One of the calculated weights is selected. In addition, when an interference signal as shown in FIG. 1C exists, the array processing control unit 163 applies CMA among the weights calculated by the respective adaptive array processing units 152-1 to 152-k. One of the calculated weights is selected. When there are a plurality of selectable weights, the weights calculated in the subchannel where the ratio between the power of the interference signal in the received signal and the power of the desired signal is large may be selected.

  The array processing control unit 163 applies the weights to the multipliers 153-1-1 to 153-1 -k and the multipliers 153-2-1 to 153-2 for the adaptive array processing unit 152 that has calculated the selected weights. output to k. At this time, adaptive array processing section 152 outputs the weight calculated for reception signal 1 to multipliers 153-1-1 to 153-1-k, and the weight calculated for reception signal 2 is multiplier 153. 2-1 to 153-2-k. That is, array processing control section 163 selects a weight effective for suppression of interference signals among the weights calculated in each adaptive array processing sections 152-1 to 152-k based on the detection result of interference signals.

  Multipliers 153-1-1 to 153-1-k receive subchannel signals corresponding to themselves from filter units 161-1-1 to 161-1-k and are selected by array processing control unit 163. A weight for received signal 1 is input from adaptive array processing section 152. Multipliers 153-1-1 to 153-1-k multiply the input subchannel signals and weights, and output the multiplication results to corresponding subchannel adders 154-1 to 154-k.

  Multipliers 153-2-1 to 153-2-k receive subchannel signals corresponding to themselves from filter units 161-2-1 to 161-2-k and are selected by array processing control unit 163. A weight for received signal 2 is input from adaptive array processing section 152. Multipliers 153-2-1 to 153-2-k multiply the input sub-channel signal and the weight, and output the multiplication results to corresponding sub-channel adders 154-1 to 154-k.

  Each of adders 154-1 to 154-k converts subchannel signals corresponding to itself to multipliers 153-1-1 to 153-1-k and multipliers 153-1 to 153-2-k. Enter from. Adders 154-1 to 154-k add the subchannel signal of received signal 1 and the subchannel signal of received signal 2 and output the addition result to signal combining section 164. The signal combining unit 164 combines the added subchannel signals input from the adders 154-1 to 154-k into one signal, and outputs the combined signal to the demodulation unit 156.

  Demodulation section 156 extracts symbols demapped by orthogonal demodulation processing from the received signal subjected to array processing for each subchannel, and performs error correction decoding processing on the extracted symbols to obtain final data. Get the series. Demodulation section 156 outputs the acquired data series to MAC layer processing section 122.

  FIG. 4 is a flowchart showing a transmission process performed by the wireless communication apparatus 120 according to this embodiment. When transmission processing is started in wireless communication apparatus 120, modulation section 131 performs symbol correction processing after performing error correction coding processing on transmission data on which processing related to the MAC layer has been performed in MAC layer processing section 122. To generate a transmission signal (step S11).

The filter units 141-1 to 141-k extract sub-channel component signals, which are associated with each other, from the transmission signals generated by the modulation unit 131, thereby converting the transmission signals into signals for each sub-channel. Divide (step S12).
The power allocation units 142-1 to 142-k allocate transmission power for each subchannel to the transmission signals divided into signals for each subchannel in the filter units 141-1 to 141-k (step S13).

  The signal combining unit 143 combines the k signals to which power has been allocated for each subchannel in the power allocation units 142-1 to 142-k into one signal (step S14), and performs radio frequency on the combined signal. Signal processing such as up-conversion is performed and transmitted from the antenna 128 to the wireless communication apparatus 120 of the destination station (step S15), and the transmission process is terminated.

  FIG. 5 is a flowchart illustrating a reception process performed by the wireless communication device 120 according to the present embodiment. When reception processing is started in the wireless communication device 120, a signal received by the antenna 128 is input to the reception signal processing unit 124, and a reception signal (reception signal 1) subjected to signal processing such as down-conversion to the baseband frequency. The received signal 2) is input to the filter units 161-1-1 to 161-1-k and the filter units 161-2-1 to 161-2-k (step S21).

  The filter units 161-1-1 to 161-1-k extract the received signal 1 for each subchannel by extracting the subchannel component signals to which the filter units 161-1-1 to 161-1-k are associated from the input received signal 1. Divide into signals. Similarly, the filter units 161-2-1 to 161-2-k extract the received signal 1 from the input received signal 2 by extracting the subchannel component signal to which the filter unit 161-2 to 161-2-k is associated. Each signal is divided (step S22).

  The interference detection unit 162 acquires the power level P1 of the received signal in the subchannel (low power density band) in which the transmission power assigned in the radio communication device 120 on the transmission side is less than the predetermined power (step S23-1). In addition, the interference detection unit 162 acquires the power level P2 of the received signal in the subchannel (high power density band) in which the transmission power allocated in the radio communication device 120 on the transmission side is equal to or higher than the predetermined power (step S23-2). .

  Among the adaptive array processing units 152-1 to 152-k, the adaptive array processing unit 152 corresponding to the subchannel to which transmission power less than the predetermined power is allocated in the transmission-side wireless communication apparatus 120 is weighted based on the PI standard. W1 is calculated (step S24-1). In addition, among the adaptive array processing units 152-1 to 152-k, the adaptive array processing unit 152 corresponding to the subchannel to which transmission power equal to or higher than the predetermined power is assigned in the wireless communication device 120 on the transmission side is based on the CMA standard. The weight W2 is calculated (step S24-2).

  The array processing control unit 163 determines whether or not the difference (P2−P1) between the power level P1 and the power level P2 detected by the interference detection unit 162 is equal to or greater than a predetermined threshold (step S25). When the difference is less than the threshold (step S25: NO), the array processing control unit 163 selects the weight W1 calculated based on the PI norm (step S26), and applies the weight to other bands, The process proceeds to step S30.

  When the difference (P2−P1) between the power level P1 and the power level P2 is equal to or greater than the threshold (step S25: YES), the array processing control unit 163 determines the weight W1 calculated based on the PI norm and the CMA norm. It is determined whether or not the weight W2 calculated on the basis matches (step S27). When the PI normative weight W1 and the CMA normative weight W2 do not match (step S27: NO), the array processing control unit 163 selects the weight W2 calculated based on the CMA norm (step S28), and the weight Is applied to other bands, and the process proceeds to step S30.

When the PI norm weight W1 and the CMA norm weight W2 match (step S27: YES), the array processing control unit 163 selects either or both of the weights calculated based on the PI norm or the CMA norm (step S29). ). When both weights are used, each weight is applied to the calculated band.
The signal synthesizer 164 synthesizes the signals of the subchannels that have been array-processed using the weight selected by the array processing controller 163 into one signal, and outputs the synthesized signal to the demodulator 156 (step S30).

  The demodulator 156 demodulates and decodes the signal combined by the signal combiner 164 to acquire a data sequence, outputs the acquired data sequence to the MAC layer processor 122 (step S31), and performs reception processing. Terminate.

  As described above, the radio communication device 120 on the transmission side divides the frequency band used for communication into k subchannels and transmits a transmission signal with a power difference for each subchannel, and the radio communication device 120 on the reception side receives The received signal is divided into k subchannels, and the difference (or ratio) in received power of each subchannel is compared with the difference in power in the transmission signal to determine the presence / absence of an interference signal and the power in the received signal. Based on the determination regarding the interference signal, the radio communication device 120 on the reception side selects whether to suppress the interference signal using a weight calculated based on either the PI norm or the CMA norm. Thereby, even if it is a case where the state of the interference signal in a received signal cannot be grasped | ascertained in advance, an interference signal can be suppressed using a blind algorithm, and communication can be performed.

<Second Embodiment>
In the wireless communication system according to the second embodiment, the accuracy of suppressing the interference signal is achieved by using the transmission-side wireless communication apparatus with feedback based on the presence / absence of the interference signal determined by the reception-side wireless communication apparatus and its power. It is to improve. Since the configuration of the wireless communication apparatus in the present embodiment is the same as that of the wireless communication apparatus 120 in the first embodiment, the description thereof is omitted.

FIG. 6 is a diagram illustrating an example of a pattern table indicating the power density assigned to each subchannel in the second embodiment. The pattern table shown in the figure has columns of an identification number item for identifying an allocation pattern and items corresponding to the first to Nth bands when the frequency band used for communication is divided. doing. Each row in the pattern table exists for each power allocation pattern. In the example shown in the figure, M power allocation patterns are shown. Note that the allocation pattern is determined so that the total transmission power is constant. B _n indicates the ratio of each band to the frequency band when the frequency band used in communication is divided, and P _n indicates the ratio of transmission power (power density) of each divided band.

  For example, in the first to fourth patterns, the frequency band used in communication is divided into two subchannels, and the transmission power allocated to each subchannel is different. In the first pattern, the same transmission power is allocated to two subchannels. In the second to fourth patterns, the transmission power allocated to one subchannel is increased, and the power difference (power ratio) is changed. Yes. In this way, patterns having different transmission power allocations and different transmission power differences (ratio) are prepared in advance, the patterns are sequentially switched and transmitted, and the presence / absence of interference signals and the power thereof are received in the radio communication apparatus 120 on the receiving side. Determine. Note that the pattern table is stored in advance and shared between the transmission side and the reception side. The transmission side and the reception side perform switching of allocation patterns in synchronization.

  FIG. 7 is a sequence diagram illustrating an operation example of the wireless communication device 120 (120a, 120b) in the wireless communication system of the present embodiment. In the wireless communication system, when the wireless communication device 120a and the wireless communication device 120b start communication, the wireless communication device 120a on the transmission side transmits a transmission signal in the second pattern of FIG. 6 (step S41).

  The reception-side wireless communication device 120b determines that there is an interference signal because there is no difference in the received power between the low power density band and the high power density band in the received signal (FIG. 7A). Further, the radio communication device 120b on the receiving side determines that the received power of the interference signal included in the received signal is higher than the received power of the desired signal over the frequency band used for communication, and the weight calculated based on the PI standard Select to perform array processing using. The wireless communication device 120b is configured so that the reception power of the desired signal is lower than the reception power of the interference signal over the frequency band of the reception signal in order to increase the effect of suppressing the interference signal by the array processing based on the PI standard. The wireless communication device 120a is instructed to allocate power that has a low power density over the entire frequency band (step S42).

  The wireless communication device 120a on the transmission side transmits a transmission signal with the power allocation set to a low power density over the frequency band used for communication in response to an instruction from the wireless communication device 120b on the reception side (step S43). As a result, the radio communication device 120b on the receiving side performs array processing using the weights calculated based on the PI standard over the entire frequency band (FIG. 7B).

  Next, a case where the reception power of the interference signal in the reception signal of the wireless communication device 120b changes will be described. When the interference signal in the received signal decreases and becomes lower than the received power of the desired signal, the radio communication apparatus 120b on the receiving side cannot sufficiently suppress the interference signal by the array processing with the weight based on the PI standard. In such a case, the transmission-side wireless communication device 120a transmits the transmission signal again with the second pattern in FIG. 6 (step S45).

  The radio communication device 120b on the receiving side corresponds to the difference in the received power between the low power density band and the high power density band in the received signal, and the difference in the received power between the low power density band and the high power density band in the transmitted signal. Therefore, it is determined that there is no interference signal or the received power is lower than the received power of the desired signal (FIG. 7C). The radio communication device 120b on the receiving side selects based on the determination result to perform the array processing using the weight calculated based on the CMA norm. In order to enhance the effect of interference signal suppression by array processing based on the CMA standard, the wireless communication device 120b extends over the entire frequency band so that the received power of the desired signal is constant over the frequency band of the received signal. The wireless communication device 120a is instructed to allocate power at which the transmission power is constant (step S46). The transmission power instructed at this time is at least higher than the power allocated to the low power density band.

  The wireless communication device 120a on the transmission side transmits a transmission signal with constant power allocation in the transmission signal in response to an instruction from the wireless communication device 120b on the reception side (step S47). As a result, the radio communication device 120b on the receiving side performs array processing using the weights calculated based on the CMA norm over the entire frequency band (FIG. 7D).

  As described above, in the operations from step S41 to step S43, the wireless communication system of the present embodiment is configured such that the received power of the desired signal is lower than the received power of the interference signal (SIR <0; FIG. 7 ( b)) By assigning power to the transmission signal, it is possible to enhance the effect of suppressing the interference signal using the PI standard on the reception side. In step S45 to step S47, the radio communication system according to the present embodiment performs transmission so that the reception power of the desired signal is higher than the reception power of the interference signal (SIR> 0; FIG. 7 (d)). By allocating power to the signal, it is possible to enhance the effect of suppressing the interference signal using the CMA standard on the receiving side.

<Third Embodiment>
In the wireless communication system of the first embodiment, the configuration of the wireless communication device 120 in the case of performing single carrier communication is shown. In the third embodiment, the configuration of the wireless communication device 120 in the case of performing communication by a multicarrier transmission method. It is. As an example, a case where an OFDM modulation scheme is used will be described. FIG. 8 is a block diagram illustrating a configuration example of the transmission signal processing unit 126 according to the third embodiment. The transmission signal processing unit 126 includes a modulation unit 131, a serial / parallel conversion unit 132, power allocation units 142-1 to 142-k, and an IDFT unit 133. The power allocation units 142-1 to 142-k are provided corresponding to k subcarriers used in the OFDM modulation scheme in the present embodiment.

  As in the first embodiment, the modulation unit 131 performs signal processing such as encoding and modulation on the transmission data output from the MAC layer processing unit 122. Modulation section 131 outputs a transmission signal obtained by performing signal processing to serial / parallel conversion section 132. The serial / parallel converter 132 converts the input transmission signal into k signal sequences corresponding to each subcarrier, and inputs the respective signal sequences to the power allocation units 142-1 to 142-k.

  The power allocation units 142-1 to 142-k adjust the signal level (amplification or attenuation) so as to obtain predetermined power allocated to each subcarrier with respect to the signal sequence input from the serial / parallel conversion unit 132. And output to the IDFT unit 133. The IDFT unit 133 converts the signal sequence output from the power allocation units 142-1 to 142-k from a frequency domain signal to a time domain signal and outputs the signal to the antenna 128.

  FIG. 9 is a block diagram illustrating a configuration of the reception signal processing unit 124 in the present embodiment. The configuration of the received signal processing unit 124 shown in the figure is a configuration in the case where the wireless communication apparatus 120 includes two antennas 128 as in the first embodiment. The received signal processing unit 124 includes DFT units 151-1 and 151-2, adaptive array processing units 152-1 to 152-k, multipliers 153-1-1 to 153-1-k, and multipliers 153- 2-1 to 153-2-k, adders 154-1 to 154-k, a parallel / serial converter 155, a demodulator 156, an interference detector 162, and an array processing controller 163. ing.

Adaptive array processing units 152-1 to 152-k, multipliers 153-1-1 to 153-1-k, multipliers 153-1 to 153-2-k, and adders 154-1 to 154 −k is provided corresponding to the subcarrier.
Note that adaptive array processing units 152-1 to 152-k, multipliers 153-1-1 to 153-1-k, multipliers 153-1 to 153-2-k, and adder 154-1. ˜154-k and the demodulator 156 are the same as those in the first embodiment, and thus the description thereof is omitted.

  The DFT unit 151-1 receives the received signal 1 received by one of the two antennas 128 provided in the wireless communication apparatus 120. The received signal 2 received by the other antenna 128 is input to the DFT unit 151-2. The DFT unit 151-1 converts the input received signal 1 from a time-domain signal to a frequency-domain signal, and converts the k subcarrier signals obtained by the conversion into an interference detection unit 162 and an adaptive array processing unit. 152-1 to 152-k and multipliers 153-1-1 to 153-1-k. The DFT unit 151-2 converts the input received signal 2 from a time-domain signal to a frequency-domain signal, and converts the k subcarrier signals obtained by the conversion into an interference detection unit 162 and an adaptive array processing unit. 152-1 to 152-k and multipliers 153-1 to 153-2-k.

  Similarly to the first embodiment, the interference detection unit 162 receives signals based on the power of each subcarrier signal output from the DFT unit 151-1 and the power allocated to each subcarrier on the transmission side. The presence / absence of an interference signal in signal 1 and its power are determined. In addition, interference detection section 162 determines whether or not there is an interference signal in received signal 2 based on the power of the signal of each subcarrier output from DFT section 151-2 and the power allocated to each subcarrier on the transmission side. And its power. The interference detection unit 162 outputs the detection result of the interference signal to the array processing control unit 163.

  Which weight is used by array processing control section 163 based on the weight calculated in each adaptive array processing section 152-1 to 152-k and the detection result of the interference signal output from interference detecting section 162? Select. That is, the array processing control unit 163 in the present embodiment replaces the interference signal detection result for each subchannel in the first embodiment, based on the interference signal detection result for each subcarrier, and the adaptive array processing unit 152. Which weight to use among the weights calculated in −1 to 152-k is selected.

  The parallel / serial converter 155 receives the signals of the subcarriers subjected to array processing by weighted combining using the weight selected by the array processing control unit 163 from the adders 154-1 to 154-k. The The parallel / serial converter 155 performs parallel / serial conversion on each input subcarrier signal, converts the signal into one signal string, and outputs the signal string to the demodulator 156.

  FIG. 10 is a flowchart for performing transmission processing performed by the wireless communication apparatus 120 according to the present embodiment. When transmission processing is started in wireless communication apparatus 120, modulation section 131 performs symbol correction processing after performing error correction coding processing on transmission data on which processing related to the MAC layer has been performed in MAC layer processing section 122. To generate a transmission signal (step S51).

The serial / parallel converter 132 performs serial / parallel conversion on the transmission signal generated in the modulator 131, converts the transmission signal into k signal sequences corresponding to each subcarrier, and converts each signal to a power allocation unit. Input to 142-1 to 142-k (step S52).
The power allocation units 142-1 to 142-k allocate power for each subcarrier to the transmission signal converted into the signal sequence for each subcarrier in the serial / parallel conversion unit 132 (step S53).

  IDFT section 133 performs IDFT on the k signal sequences to which power is allocated for each subcarrier in power allocation sections 142-1 to 142-k, and converts the frequency domain signal into a time domain signal. (Step S54), the obtained time domain signal is subjected to signal processing such as up-conversion to a radio frequency and transmitted from the antenna 128 to the radio communication device 120 of the destination station (Step S55). End.

  FIG. 11 is a flowchart illustrating a reception process performed by the wireless communication device 120 according to this embodiment. When reception processing is started in the wireless communication device 120, a signal received by the antenna 128 is input to the reception signal processing unit 124, and a reception signal (reception signal) subjected to signal processing such as down-conversion to the baseband frequency is performed. 1 and the received signal 2) are input to the DFT units 151-1 and 151-2 (step S61).

  The DFT unit 151-1 converts the received signal 1 into a signal for each subcarrier by performing DFT on the input received signal 1 and converting it from a time domain signal to a frequency domain signal. Similarly, the DFT unit 151-2 performs DFT on the input received signal 2 to convert the received signal 2 into a signal for each subcarrier (step S62).

  The interference detection unit 162 detects the power level P1 of the received signal in a subcarrier (low power density band) in which the transmission power assigned in the radio communication device 120 on the transmission side is less than a predetermined power (step S63-1). In addition, the interference detection unit 162 detects the power level P2 of the received signal in a subcarrier (high power density band) in which the transmission power allocated in the radio communication device 120 on the transmission side is equal to or higher than a predetermined power (step S63-2). .

  Among adaptive array processing units 152-1 to 152-k, adaptive array processing unit 152 corresponding to a subcarrier to which transmission power less than a predetermined power is allocated in radio communication apparatus 120 on the transmission side is weighted based on the PI standard. W1 is calculated (step S64-1). In addition, among the adaptive array processing units 152-1 to 152-k, the adaptive array processing unit 152 corresponding to the subcarrier to which transmission power equal to or higher than the predetermined power is assigned in the wireless communication device 120 on the transmission side is based on the CMA standard. The weight W2 is calculated (step S64-2).

  The array processing control unit 163 determines whether or not the difference (P2−P1) between the power level P1 detected by the interference detection unit 162 and the power level P2 is equal to or greater than a predetermined threshold (step S65). If the difference is less than the threshold (step S65: NO), the array processing control unit 163 selects a weight calculated based on the PI norm (step S66), applies the weight to other bands, and performs processing. Advances to step S70.

  When the difference (P2−P1) between the power level P1 and the power level P2 is equal to or greater than the threshold (step S65: YES), the array processing control unit 163 determines the weight W1 calculated based on the PI norm and the CMA norm. It is determined whether or not the weight W2 calculated on the basis matches (step S67). If the PI normative weight W1 and the CMA normative weight W2 do not match (step S67: NO), the array processing control unit 163 selects the weight W2 calculated based on the CMA norm (step S68), and the weight Is applied to other bands, and the process proceeds to step S70.

When the weights of the PI norm and the CMA norm match (step S67: YES), the array processing control unit 163 selects either or both of the weights calculated according to either the PI norm or the CMA norm (step S67). S69). When both weights are used, each weight is applied to the calculated band.
The parallel / serial converter 155 performs parallel / serial conversion on the signals of each subcarrier subjected to the array processing using the weight selected by the array processing control unit 163 to convert the signals into one signal string, and obtains the result by the conversion. The obtained signal sequence is output to the demodulator 156 (step S70).

  The demodulator 156 demodulates and decodes the signal sequence obtained in the parallel / serial converter 155 to acquire a data sequence, and outputs the acquired data sequence to the MAC layer processor 122 (step S71). The reception process is terminated.

  Also in the present embodiment, similarly to the first embodiment, the radio communication apparatus 120 on the reception side calculates based on any of the PI norm and the CMA norm based on the determination regarding the interference signal in each subcarrier. It is selected whether to suppress the interference signal by using the determined weight. Thereby, even if it is a case where the state of the interference signal in a received signal cannot be grasped | ascertained in advance, an interference signal can be suppressed using a blind algorithm, and communication can be performed.

<Fourth Embodiment>
In the wireless communication system according to the fourth embodiment, as in the wireless communication system according to the second embodiment, the accuracy of suppressing the interference signal by performing feedback from the reception-side wireless communication apparatus to the transmission-side wireless communication apparatus. Is to improve. Since the configuration of the wireless communication apparatus in this embodiment is the same as that of the wireless communication apparatus 120 in the third embodiment, the description thereof is omitted. Also in the present embodiment, as in the pattern table (FIG. 6) in the second embodiment, the transmission side and the reception side store in advance a pattern table indicating the power density assigned to each subcarrier. And share. In addition, the transmission side and the reception side perform switching of allocation patterns in synchronization.

  FIG. 12 is a sequence diagram showing an operation of the wireless communication device 120 (120a, 120b) in the wireless communication system of the present embodiment. In the wireless communication system, when the wireless communication device 120a and the wireless communication device 120b start communication, the transmission-side wireless communication device 120a transmits an assignment pattern in which low transmission power and high transmission power are alternately combined to transmit each subcarrier. A transmission signal is transmitted as power (step S81).

  The radio communication device 120b on the reception side has a difference (or ratio) in received power between a low power density subcarrier and a high power density subcarrier in the received signal. Or the ratio), it is determined that there is an interference signal (FIG. 12A). In addition, the reception-side wireless communication device 120b determines that the received signal is different in the received power of each subcarrier in the received signal from the power allocation in the pattern table and that there is a difference in received power between adjacent subcarriers. The received power of the included interference signal is determined to be higher than the received power of the desired signal of the subcarrier to which low power is allocated on the transmitting side, and lower than the received power of the desired signal of the subcarrier to which higher power is allocated on the transmitting side. To do.

  The radio communication apparatus 120b on the reception side transmits the power allocated to each subcarrier on the transmission side so that the reception power of the desired signal in the reception signal is lower than the reception power of the interference signal across the subcarriers in step S82. The wireless communication device 120a is instructed to allocate the power (step S82).

  The transmission-side radio communication apparatus 120a transmits a transmission signal in accordance with an instruction from the reception-side radio communication apparatus 120b with the power allocation in each subcarrier aligned with a low transmission power (step S83). As a result, the radio communication device 120b on the receiving side performs array processing using the weights calculated based on the PI norm over all subcarriers (FIG. 12 (b)).

  Here, a case where the reception power of the interference signal in the reception signal is changed will be described. When the interference signal in the received signal decreases and becomes lower than the received power of the desired signal, the radio communication apparatus 120b on the receiving side cannot sufficiently suppress the interference signal by the array processing with the weight based on the PI standard. In such a case, the radio communication device 120a on the transmission side transmits a transmission signal again using an allocation pattern in which low transmission power and high transmission power are alternately combined as the transmission power of each subcarrier (step S85).

  The wireless communication device 120b on the reception side has a difference (or ratio) in received power between the low power density subcarriers and the high power density subcarriers in the received signal. Therefore, it is determined that there is no interference signal or that the received power is lower than the received power of the desired signal (FIG. 12 (c)). The radio communication device 120b on the receiving side selects based on the determination result to perform the array processing using the weight calculated based on the CMA norm. Radio communication apparatus 120b transmits over the entire frequency band so that the received power of the desired signal is constant across all subcarriers in order to enhance the effect of suppressing interference signals by array processing based on the CMA standard. The wireless communication device 120a is instructed to allocate power with constant power (step S86). The transmission power instructed at this time is set to a power equal to or higher than the low transmission power allocated to the subcarrier in step S85.

  The wireless communication device 120a on the transmission side transmits a transmission signal with constant power allocation in the transmission signal in response to an instruction from the wireless communication device 120b on the reception side (step S87). As a result, the radio communication device 120b on the receiving side performs array processing using the weights calculated based on the CMA norm over the entire frequency band (FIG. 12 (d)).

As described above, in the operations from step S81 to step S83, the radio communication system of the present embodiment is such that the reception power of the desired signal is lower than the reception power of the interference signal in all subcarriers (SIR <0; FIG. 12B), by assigning power to the transmission signal, it is possible to enhance the effect of suppressing the interference signal using the PI standard on the reception side. Also, in steps S85 to S87, the radio communication system of the present embodiment is such that the reception power of the desired signal is higher than the reception power of the interference signal in all subcarriers (SIR>0; FIG. 12 ( d)) By allocating power to the transmission signal, it is possible to enhance the effect of suppressing the interference signal using the CMA standard on the receiving side.
In the description of the above embodiment, the adaptive array algorithm has been described centering on PI and CMA. However, the adaptive array algorithm is not limited to these, and any adaptive array standard that becomes an operation area according to the allocated transmission power can be used. An algorithm may be applied. For example, MMSE may be applied in a frequency band where SIR> 0.

  You may make it implement | achieve the wireless communication apparatus 120 in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” is a program that dynamically holds a program for a short time, like a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be realized using hardware such as PLD (Programmable Logic Device) or 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 designs and the like that do not depart from the gist of the present invention. For example, in the reception process (FIGS. 5 and 11), whether the PI norm weight and the CMA norm weight match is equal to or less than a certain value in the difference between the PI norm weight and the CMA norm weight. It may be replaced with the determination of whether or not. If the weights calculated according to the respective norms match or are equal to or less than a certain value, the weight for suppressing the similar interference signal is calculated. On the other hand, if there is a difference exceeding a certain value in the weights calculated by each standard, each standard calculates a weight that suppresses different interference signals, and either band is an adaptive array algorithm. It means not in the operating area.

Further, step S27 and step S29 may be omitted in the reception process of FIG. Similarly, step S67 and step S69 may be omitted in the reception process of FIG.
Further, feedback from the reception-side wireless communication device 120 to the transmission-side wireless communication device 120 may be performed using a modulation method that is not easily affected by interference, or a feedback-dedicated line (not shown). May be used.

  When the received power of an interference signal cannot be grasped in advance, the present invention can be applied to an application in which selection of an adaptive array algorithm used for adaptive array processing is indispensable.

120, 120a, 120b ... wireless communication device 121 ... data input / output unit 122 ... MAC layer processing unit 123 ... communication control unit 124 ... received signal processing unit 126 ... transmission signal processing unit 127 ... switch 128 ... antenna 131 ... modulation unit 132 ... Serial / parallel conversion unit 133 ... IDFT unit 141-1, 141-k ... filter unit 142-1, 142-k ... power allocation unit 143 ... signal synthesis unit 151, 151-1, 151-2 ... DFT unit 152, 152 -1, 152-k ... Adaptive array processing units 153, 153-1-1, 153-1-k, 153-2-1, 153-2-k ... Multipliers 154, 154-1, 154-k ... Addition 155 ... Parallel / serial converter 156 ... Demodulator 161-1-1, 161-1-k, 161-2-1, 161-2-k ... Filter unit 162 ... Wataru detector 163 ... array process control unit 164 ... signal synthesizer

Claims (6)

In the wireless communication system in which the first wireless communication device and the second wireless communication device perform wireless communication,
The first wireless communication device is:
Transmitting means for transmitting a signal assigned different transmission power for each of a plurality of bands divided into frequency bands used for wireless communication,
The second wireless communication device is:
Receiving means for receiving signals transmitted by the transmitting means using a plurality of antennas;
Frequency band dividing means for dividing the received signal received by the receiving means into signals of the plurality of bands;
Based on the reception power of the signal for each of the plurality of bands divided by the frequency band dividing unit and the transmission power allocated to each of the plurality of bands by the transmission unit, presence / absence of interference signals in the reception signal and reception Interference detection means for detecting power;
Weight selection means for selecting a weight to be applied in each of the bands based on the detection result of the interference detection means;
And a signal combining unit that combines the reception signals corresponding to the antennas into one signal using the weight selected by the weight selection unit. The wireless communication system according to claim 1,
The interference detection means includes
Based on a difference in received power between the plurality of bands in the received signal and a difference in transmission power between the plurality of bands assigned by the transmission unit, the received power of the interference signal is detected,
The weight selection means includes
A wireless communication system, wherein one of weights is selected from weights calculated based on different adaptive array algorithms based on a detection result of the interference detection means. In the wireless communication system according to claim 1 or claim 2,
The second wireless communication device is:
Feedback means for instructing the first wireless communication apparatus to allocate transmission power in the plurality of bands based on a detection result of the interference detection means;
The transmission means includes
A wireless communication system, wherein a transmission signal is transmitted by transmission power allocation instructed by the feedback means. Receiving means for receiving, using a plurality of antennas, transmission signals in which different transmission powers are assigned to a plurality of bands obtained by dividing frequency bands used for wireless communication;
Frequency band dividing means for dividing the received signal received by the receiving means into signals of the plurality of bands;
Interference detection for detecting the presence / absence of an interference signal in the received signal and the received power based on the received power of the signal for each of the plurality of bands divided by the frequency band dividing unit and the allocation of transmission power in the plurality of bands Means,
Weight selection means for selecting a weight to be applied in each of the bands based on the detection result of the interference detection means;
Signal combining means for combining the received signals corresponding to each of the antennas into one signal using the weight selected by the weight selecting means;
A wireless communication apparatus comprising: A wireless communication method in a wireless communication system comprising a first wireless communication device and a second wireless communication device,
A transmission step in which the first wireless communication device transmits a signal to which different transmission powers are assigned for each of a plurality of bands obtained by dividing frequency bands used for wireless communication;
A receiving step in which the second wireless communication apparatus receives the signals transmitted in the transmitting step using a plurality of antennas;
A frequency band dividing step of dividing the received signal received in the receiving step into the signals of the plurality of bands;
Based on the reception power of the signals for each of the plurality of bands divided in the frequency band division step and the transmission power allocated to each of the plurality of bands in the transmission step, presence / absence of interference signals in the reception signal and reception An interference detection step for detecting power;
A weight selection step for selecting a weight to be applied to each of the bands based on a detection result in the interference detection step;
And a signal combining step of combining the received signals corresponding to the respective antennas into one signal using the weight selected in the weight selecting step. A reception method in a wireless communication device, comprising:
A reception step of receiving, using a plurality of antennas, transmission signals to which different transmission powers are assigned for a plurality of bands obtained by dividing frequency bands used for wireless communication;
A frequency band dividing step of dividing the received signal received in the receiving step into the signals of the plurality of bands;
Interference detection for detecting presence / absence of interference signal and reception power in the received signal based on reception power of the signal for each of the plurality of bands divided in the frequency band division step and allocation of transmission power in the plurality of bands Steps,
A weight selection step of selecting a weight to be applied to each of the bands based on a detection result of the interference detection step;
A signal combining step of combining the received signals corresponding to the antennas into one signal using the weights selected in the weight selecting step;
A receiving method comprising:

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