JP2009017341A - Receiver, transmission unit, communication system, and reception quality measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance through put in a transmission line, by measuring reception quality without degrading accuracy even under an environment, where there are two or more interference base stations. <P>SOLUTION: In a mobile station, where multi-carrier communication is performed with a base station, a pilot signal extraction unit 205 extracts a first pilot signal transmitted from the first base station and a second pilot signal transmitted from one or more second base stations other than the first base station. A propagation path estimation unit 210 calculates a first propagation path estimation value from the first pilot signal for every sub-carrier to the first base station, and also calculates a second propagation path estimation value from the second pilot signal for every sub-carrier to the second base station. A weight computation unit 211 calculates weight for every sub-carrier from at least the first propagation path estimation value. An SIR measurement unit 212 measures reception quality of the data signal from first and second propagation path estimation values and the weight. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiving apparatus, a transmitting apparatus, a communication system, and a reception quality measurement method, and more particularly, to a receiving apparatus that performs wireless communication using a multicarrier transmission method typified by MC-CDMA (Multi-Carrier Code Division Multiple Access), and transmission The present invention relates to an apparatus, a communication system, and a reception quality measurement method.

  In recent years, in wireless communication, there has been a demand for higher speed and higher quality of data transmission. However, when data transmission is speeded up, the propagation path becomes a multipath environment due to a delayed wave. In single carrier transmission, inter-path interference occurs due to multipath fading, and transmission characteristics are significantly degraded.

  Therefore, OFDM (Orthogonal Frequency Division Multiplexing) that can obtain good transmission characteristics even in a multipath environment by transmitting a large number of orthogonal narrowband carriers in parallel has attracted attention.

  In addition, MC-CDMA, which multiplies modulation symbols by orthogonal codes and multiplexes and transmits the signals multiplied by each code, can obtain good transmission characteristics due to the frequency diversity effect. It is.

  In multicarrier transmission, the channel gain differs for each subcarrier due to frequency selective fading. Therefore, the capacity and quality of data communication can be improved by performing adaptive modulation, scheduling, etc. according to the signal-to-interference power ratio (SIR: Signal to Interference power Ratio) after subcarrier or despreading. it can.

  As a method for calculating SIR in a conventional MC-CDMA system, for example, there is Patent Literature 1. The prior art will be described below with reference to the drawings. FIG. 16 is a diagram illustrating an internal configuration of a base station apparatus (hereinafter referred to as “base station”) constituting a conventional wireless communication system.

  The base station includes a transmission power control unit 1601 that is notified of SIR notified from a mobile station apparatus (hereinafter referred to as “mobile station”). Also, a transmission power variable unit 1605 that changes the power of each subcarrier by a control signal from the error correction coding unit 1602, the mapping unit 1603, the spreading unit 1604, and the transmission power control unit 1601 is provided for each code 1 to code C. Yes. Furthermore, a code multiplexing unit 1606, a pilot signal generation unit 1607, a pilot signal insertion unit 1608, an inverse fast Fourier transform (IFFT) unit 1609, a guard interval (GI) addition unit 1610, a radio transmission unit 1611, and an antenna unit 1612 are provided. . An adaptive modulation unit (not shown) that controls the modulation scheme and error correction coding rate may be provided based on CQI notified from the mobile station.

  The signal transmitted from the base station shown in FIG. 16 is received by the mobile station through the propagation path. Here, the configuration of the mobile station will be described with reference to FIG. FIG. 17 is a diagram showing an internal configuration of a mobile station constituting a conventional wireless communication system.

  A signal received by radio reception section 1702 via antenna section 1701 is removed by GI removal section 1703 and then decomposed into subcarriers by FFT section 1704. Thereafter, the received pilot signal is extracted by pilot signal extraction section 1705. The extracted received pilot signal is input to weight calculation section 1706. Weight calculation section 1706 generates a weight for each subcarrier to compensate for changes in the phase and amplitude of the data signal received on the propagation path, and inputs the weight to propagation path compensation section 1707.

  On the other hand, the data signal is input to propagation path compensation section 1707, compensated for changes in phase and amplitude received through the propagation path, and outputs a value for each subcarrier to despreading section 1708. Despreading section 1708 performs despreading processing using any one of codes 1 to C used on the transmission side, and outputs values to de-mapping section 1709 and SIR measurement section 1710. De-mapping section 1709 performs de-mapping by modulation performed at the base station, and error correction decoding section 1711 performs error correction decoding processing, and then outputs information data. On the other hand, SIR measurement section 1710 measures the received SIR after despreading.

  Here, the calculation method of SIR in Patent Document 1 will be described with reference to FIG. Pilot signal extraction section 1705 extracts a pilot signal from the received signal, and inputs the pilot signal to inverse modulation section 1801 and subtraction section 1802. Also, the pilot signal sequence generated by pilot signal generation section 1803 is input to inverse modulation section 1801 and remodulation section 1804. Inverse modulation section 1801 divides the input from pilot signal extraction section 1705 by the input from pilot signal generation section 1803 and inputs the result to averaging section 1805. The averaging unit 1805 improves the estimation accuracy due to interference by performing averaging processing using a plurality of pilot signals subjected to similar processing, and inputs the result to the squaring unit 1806. The square unit 1806 squares the absolute value of the input signal and inputs it to the division unit 1807 as the desired signal power after despreading.

On the other hand, remodulation section 1804 generates a replica of the desired signal contained in the output of despreading section 1705 by multiplying the output of averaging section 1805 by the pilot signal sequence generated by pilot signal generation section 1803. , Input to the subtraction unit 1802. Subtractor 1802 subtracts the output of remodulator 1804 from the output of pilot signal extractor 1705, calculates the interference signal component, and inputs the result to squarer 1808. Thereafter, interference unit power is calculated by performing a square process of the absolute value of the input signal in the square unit 1808. Further, in order to improve the estimation accuracy of the interference signal power, the interference power is averaged by a plurality of pilot signals subjected to the same processing in the averaging unit 1809 and output to the division unit 1807. The division unit 1807 calculates the SIR after despreading by dividing the output (desired signal power) of the square unit 1806 by the output (interference power) of the averaging unit 1809.
JP 2002-246958 A

  In the SIR calculation method in Patent Document 1 described above, the square of the absolute value obtained by subtracting the desired signal component from the received signal is used as the interference power. Therefore, when there are a plurality of interference base stations, a correlation value between the interference signals is included in addition to the square of the absolute value of each interference signal. Therefore, in the SIR calculation method in Patent Document 1, the averaging unit 1805 or the averaging unit 1809 performs averaging processing using a plurality of pilot signals, thereby suppressing the correlation value between the interference pilot signals, The estimation accuracy of SIR is improved.

  However, when a large number of pilot signals are used, the transmission efficiency decreases. On the other hand, when the number of pilot signals is not sufficient, the correlation value between each interference pilot signal cannot be suppressed, and there is a possibility that the estimation accuracy of SIR may deteriorate.

  The present invention has been made in view of such circumstances, and in an environment where there are a plurality of interfering base stations, the reception quality can be measured without degrading accuracy, and the throughput in the transmission path can be measured. It is an object of the present invention to provide a receiving device, a transmitting device, a communication system, and a reception quality measuring method capable of improving the quality.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the receiving apparatus according to the present invention is a receiving apparatus that performs multicarrier communication with a transmitting apparatus, and includes a first pilot signal transmitted from the first transmitting apparatus and a device other than the first transmitting apparatus. A pilot extraction unit that extracts a second pilot signal transmitted from one or more second transmission devices, and a first propagation path for each subcarrier for the first transmission device from the first pilot signal A propagation path estimator that calculates a second propagation path estimation value for each subcarrier for the second transmission device from the second pilot signal, and at least the first propagation path estimation value A weight calculation unit for calculating a weight for each subcarrier from the received signal, and a reception quality measurement unit for measuring the reception quality of the data signal from the first and second propagation path estimated values and the weight. It is set to.

  Thus, the first propagation path estimated value calculated from the first pilot signal, the second propagation path estimated value calculated from the second pilot signal, and at least the first propagation path estimated value are calculated. Since the reception quality of the data signal is measured using the weights to be received, it is possible to estimate the reception quality after despreading that does not depend on the pilot correlation between the interfering base stations. As a result, it is possible to determine an appropriate error correction coding rate and modulation method in a propagation path for communication, and it is possible to improve throughput characteristics.

  (2) Further, in the receiving apparatus according to the present invention, the pilot extraction unit extracts the first and second pilot signals in which pilots are transmitted using different subcarriers, and the propagation path estimation unit includes: Then, using the first and second pilot signals, the first transmission apparatus estimates the propagation path in the subcarrier to which the pilot has been transmitted, and the first transmission apparatus uses the propagation path estimation value. While calculating the first propagation path estimation value by estimating the propagation path in the subcarrier that did not transmit the pilot, the second transmission apparatus estimates the propagation path in the subcarrier that transmitted the pilot, By using the propagation path estimation value, the second transmission apparatus estimates the propagation path in the subcarrier that did not transmit the pilot. It is characterized by calculating the propagation path estimated value.

  In this way, since the first and second pilot signals transmitted using subcarriers with different pilots are extracted, for example, by using the FDM pilot, the pilot from the desired base station and the interference base station Therefore, it is possible to estimate the propagation path even for a carrier in which no pilot is transmitted by interpolating between pilot subcarriers.

  (3) In the reception apparatus of the present invention, the pilot extraction unit uses the spreading code to spread the first pilot signal transmitted in at least one of the time direction and the frequency direction, and transmit the first pilot signal. A second pilot signal that is spread and transmitted using a spreading code different from the pilot signal is extracted, and the propagation path estimator performs the first pilot on the first and second pilot signals. The first propagation path estimated value is calculated by despreading with the spreading code used for the signal, while the second propagation path is obtained by despreading with the spreading code used for the second pilot signal. It is characterized by calculating an estimated value.

  Thus, the first pilot signal spread and transmitted in at least one of the time direction and the frequency direction using the spreading code, and the first pilot signal spread and transmitted using a spreading code different from the first pilot signal are transmitted. 2 pilot signals are extracted, for example, a CDM pilot is transmitted from a base station (transmitting apparatus), and a pilot from a desired base station and a pilot from an interfering base station are separated by despreading processing. By doing so, it becomes possible to estimate the propagation path between each base station.

  (4) Further, in the receiving apparatus of the present invention, the pilot extraction unit performs transmission of an impulse response of the propagation path in the apparatus body and the first pilot signal transmitted by applying phase rotation to the pilot symbol for each subcarrier. A second pilot signal transmitted by applying a phase rotation different from that of the first pilot signal to the pilot symbol in a separable manner, and extracting the second pilot signal to be transmitted; While converting to the time domain, extracting the first propagation path impulse response to the first transmission device, and converting the impulse response to the frequency domain, the first propagation path estimation value is calculated, The second propagation path impulse response to the transmitter 2 is extracted, and the second propagation path estimated value is obtained by converting the impulse response into the frequency domain. It is characterized in that out.

  In this way, the first pilot signal transmitted by applying phase rotation to the pilot symbols for each subcarrier and the phase rotation different from that of the first pilot signal so that the impulse response of the propagation path can be separated in the apparatus main body. Since the second pilot signal transmitted by giving to the pilot symbol is extracted, for example, by using a window function that can obtain an impulse response of each base station (transmitting device), It is possible to estimate the propagation path.

  (5) In the receiving apparatus of the present invention, a method for calculating the first propagation path estimated value in the propagation path estimating unit is different from a method for calculating the second propagation path estimated value. It is said.

  In this way, by making the method for calculating the first propagation path estimated value different from the method for calculating the second propagation path estimated value, the circuit scale in the mobile station (receiving apparatus) can be reduced. It becomes.

  (6) Moreover, in the receiving apparatus of the present invention, the propagation path estimation unit estimates the phase and amplitude in the first propagation path with respect to the first transmission apparatus, while the second transmission apparatus with respect to the second transmission apparatus. Only the power in the propagation path is estimated.

  As described above, by estimating only the power in the second propagation path while estimating the phase and amplitude in the first propagation path, for example, it is possible to simplify the processing when estimating the interference power. Become.

  (7) Further, in the receiving device of the present invention, the receiving device of the present invention further includes an other interference power measuring unit that obtains power of other interference that is interference other than the signal transmitted from the second transmitting device, and the weight calculating unit includes: A weight for each subcarrier is calculated based on the power of the other interference, and the reception quality measurement unit calculates a total interference based on the power of the signal transmitted from the second transmission apparatus and the power of the other interference. The power is calculated, and the reception quality of the data signal is measured based on the total interference power.

  Thus, the total interference power is calculated based on the power of the signal transmitted from the second transmitter and the power of other interference, and the reception quality of the data signal is measured based on the total interference power. From this, it is possible to estimate not only inter-cell interference power but also other interference power and noise power, so that it becomes possible to determine a more appropriate error correction coding rate and modulation scheme based on these estimation results, Furthermore, throughput characteristics can be improved.

  (8) Moreover, the transmission apparatus of the present invention is a transmission apparatus that performs multicarrier communication with a reception apparatus, and a transmission unit that transmits a first pilot signal and a transmission frame to the reception apparatus; Based on the first propagation path estimated value estimated from the receiving device based on the first pilot signal and the second pilot signal transmitted from one or more second transmitting devices other than the transmitting device. A reception unit that receives a signal indicating reception quality measured using the second propagation path estimation value estimated in step S1 and a weight calculated based on at least the first propagation path estimation value; A transmission parameter determining unit that determines a transmission parameter including at least one of a spreading factor, a code multiplexing number, a modulation scheme, and a coding rate based on quality; and the transmission parameter based on the determined transmission parameter. It is characterized in that it comprises a transmission frame generation unit for generating a frame.

  In this way, transmission parameters including at least one of the spreading factor, the number of code multiplexes, the modulation scheme, and the coding rate are determined based on the reception quality notified from the receiving apparatus, and the transmission frame is determined based on the transmission parameters. Since it is generated, it is possible to determine an appropriate error correction coding rate and modulation method in a communication channel for communication, and it is possible to improve throughput characteristics.

  (9) Moreover, the communication system of this invention is a communication system which performs multicarrier communication between a transmitter and a receiver, Comprising: The said receiver is a 1st pilot signal transmitted from the said transmitter, A second pilot signal transmitted from one or more other transmission apparatuses other than the transmission apparatus is extracted, and a first propagation path estimation value for each subcarrier for the transmission apparatus is calculated from the first pilot signal. On the other hand, a second propagation path estimation value for each subcarrier for the other transmission device is calculated from the second pilot signal, and a weight for each subcarrier is calculated from at least the first propagation path estimation value, While measuring the reception quality of the data signal from the first and second propagation path estimation values and the weight, the transmission device transmits the first pilot signal to the reception device, Receiving a signal indicating the reception quality from the receiver, determining a transmission parameter including at least one of a spreading factor, the number of code multiplexes, a modulation scheme, and a coding rate based on the reception quality; The transmission frame is generated based on the above.

  Thus, in the receiving apparatus, the first propagation path estimated value calculated from the first pilot signal, the second propagation path estimated value calculated from the second pilot signal, and at least the first propagation path Since the reception quality of the data signal is measured using the weight calculated from the estimated value, it is possible to estimate the reception quality after despreading that does not depend on the pilot correlation between the interfering base stations. Then, in the transmission apparatus, a transmission parameter including at least one of a spreading factor, a code multiplexing number, a modulation scheme, and a coding rate is determined based on the reception quality, and a transmission frame is generated based on the transmission parameter From this, it becomes possible to determine an appropriate error correction coding rate and modulation method in a propagation path for communication, and thus it is possible to improve throughput characteristics.

  (10) The reception quality measurement method of the present invention is a reception quality measurement method in a communication system in which multicarrier communication is performed between a transmission device and a reception device, and is transmitted from the transmission device by the reception device. The first pilot signal and the second pilot signal transmitted from one or more other transmission apparatuses other than the transmission apparatus are extracted, and the first pilot signal for each subcarrier for the transmission apparatus is extracted from the first pilot signal. A second channel estimation value for each subcarrier for the other transmitter is calculated from the second pilot signal, and at least the first channel estimation value is calculated from the first channel estimation value. Each weight is calculated, and the reception quality of the data signal is measured from the first and second propagation path estimated values and the weight.

  Thus, in the receiving apparatus, the first propagation path estimated value calculated from the first pilot signal, the second propagation path estimated value calculated from the second pilot signal, and at least the first propagation path Since the reception quality of the data signal is measured using the weight calculated from the estimated value, it is possible to estimate the reception quality after despreading that does not depend on the pilot correlation between the interfering base stations. Then, in the transmission apparatus, a transmission parameter including at least one of a spreading factor, a code multiplexing number, a modulation scheme, and a coding rate is determined based on the reception quality, and a transmission frame is generated based on the transmission parameter From this, it becomes possible to determine an appropriate error correction coding rate and modulation method in a propagation path for communication, and thus it is possible to improve throughput characteristics.

  According to the present invention, the first propagation path estimated value calculated from the first pilot signal, the second propagation path estimated value calculated from the second pilot signal, and at least the first propagation path estimated value. Since the reception quality of the data signal is measured using the weight calculated from the above, it is possible to estimate the reception quality after despreading that does not depend on the pilot correlation between the interfering base stations. As a result, it is possible to determine an appropriate error correction coding rate and modulation method in the communication channel, so that reception quality can be measured without degrading accuracy even in environments where there are multiple interfering base stations. It is possible to improve the throughput in the transmission path.

  Hereinafter, a communication system, a base station as a transmission device, and a mobile station as a reception device according to an embodiment of the present invention will be described with reference to the drawings. In the following, the MC-CDMA base station and the mobile station according to the present invention will be described in particular by taking downlink communication (communication from the base station to the mobile station) as an example.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of a base station that constitutes the communication system according to the first embodiment of the present invention. As shown in FIG. 1, the base station includes an error correction encoding unit 101, a mapping unit 102, and a spreading unit 103 for each code 1 to code C. Also, a code multiplexing unit 104, a pilot signal generation unit 105, a pilot signal insertion unit 106, an IFFT unit 107, a GI addition unit 108, a radio transmission unit 109, an antenna unit 110, and an adaptive modulation unit that multiplex signals spread by each code 111 is provided.

  The base station inputs the information bit sequence to error correction coding section 101. In addition, adaptive modulation section 111 maps a control signal for notifying error correction coding section 101 of the error correction coding rate and the modulation scheme based on CQI (Channel Quality Information) notified from the mobile station. A control signal for notifying the unit 102 is generated.

Error correction coding section 101 performs error correction coding based on the control signal from adaptive modulation section 111. Next, the encoded bit sequence is converted into N _s data symbols such as BPSK (Binary Phase Shift Keying) and 16QAM (Quadrature Amplitude Modulation) based on the control signal from the adaptive modulation unit 111 by the mapping unit 102. Modulation is performed. Thereafter, spreading section 103 multiplies each N _s data symbol by an orthogonal code of spreading factor SF (SF is an integer equal to or greater than 1), and spreads the result into frequency blocks made up of SF subcarriers.

The above processing is similarly performed on different data series using different orthogonal codes. N _c (= N _s × SF) subcarrier data signals respectively generated from code 1 to code C are multiplexed in code multiplexing section 104 to obtain data signals for N _c subcarriers. Pilot signal generation section 105 determines a pilot signal sequence to be transmitted, and pilot signal insertion section 106 multiplexes the data signal and pilot signal. After that, an inverse fast Fourier transform (IFFT) process of N _FFT (≧ N _c ) points is performed by the IFFT unit 107 to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG.

  A signal transmitted from the base station shown in FIG. 1 is received by the mobile station through the propagation path. Here, the configuration of the mobile station configuring the communication system according to the first embodiment of the present invention will be described. FIG. 2 is a block diagram illustrating an example of the configuration of the mobile station according to the first embodiment. As shown in FIG. 2, the mobile station includes an antenna unit 201, a radio reception unit 202, a GI removal unit 203, an FFT unit 204, a pilot signal extraction unit 205, a propagation path compensation unit 206, a despreading unit 207, and a de-mapping unit. 208 and an error correction decoding unit 209. The mobile station also includes a propagation path estimation unit 210, a weight calculation unit 211, an SIR measurement unit 212, and a CQI generation unit 213.

In the mobile station, the signal received by the radio reception unit 202 via the antenna unit 201 is subjected to removal of the guard interval by the GI removal unit 203 and then converted to the subcarrier component by the FFT unit 204 of N _FFT (≧ N _c ) points. Decompose to obtain N _c subcarriers. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210. Propagation path estimation section 210 estimates the propagation path to each base station for each _Nc subcarrier using the received pilot extracted by pilot signal extraction section 205. The obtained propagation path estimated value with each base station is input to the weight calculation unit 211 and the SIR measurement unit 212.

In weight calculation section 211, ZF (Zero Forcing) weight, MRC (maximum ratio combining) weight, MMSE (minimum mean square error) weight and the like for compensating the propagation path of the data section are set for each of N _c subcarriers. It is calculated and input to the propagation path compensation unit 206 and the SIR measurement unit 212. The SIR measurement unit 212 measures the SIR using the input from the propagation path estimation unit 210 and the input from the weight calculation unit 211 and inputs the SIR to the CQI generation unit 213. The CQI generation unit 213 generates a CQI from the input SIR and notifies the generated CQI to the base station.

On the other hand, the data signal is input from the pilot signal extraction unit 205 to the propagation path compensation unit 206. The propagation path compensation unit 206 multiplies the data signal and the weight input from the weight calculation unit 211 for each of the _Nc subcarriers, thereby obtaining the data signal compensated for the phase and amplitude fluctuations received in the propagation path. obtain. Next, the data signal of the _Nc subcarriers after weight multiplication is despread in the despreading section 207 using any one of the codes 1 to C used on the transmission side, and after N _s despreads Get the data symbol. The N _s despread data symbols are input to the de-mapping unit 208. De-mapping unit 208 performs a de-mapping based on the modulation performed N _s number of data signals on the transmission side, and inputs the result to error correction decoding section 209. The error correction decoding unit 209 outputs an information bit sequence after performing error correction decoding processing.

  Here, the SIR calculation method in the communication system according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 3 is a diagram showing in detail the pilot signal extraction unit 205, the propagation path estimation unit 210, the weight calculation unit 211, and the SIR measurement unit 212 in FIG. 3, the propagation path estimation unit 210 includes a desired signal propagation path estimation unit 301, an interference signal 1 propagation path estimation unit 302-1,..., And an interference signal J propagation path estimation unit 302-J. The SIR measurement unit 212 includes a weight multiplication unit 303, a despreading unit 304, and a square unit 305. Also, for each interference signal, the weight multipliers 306-1 to J, the squares 307-1 to J, the despreading units 308-1 to J, the code multiplexing number multipliers 309-1 to J, and the interference powers are combined. 1 to J combining unit 310 and dividing unit 311.

The pilot signal extraction unit 205 extracts a pilot signal from the received signal, and transmits it to the desired signal propagation path estimation unit 301, the interference signal 1 propagation path estimation unit 302-1, ..., and the interference base station J propagation path estimation unit 302-J. input. Desired signal propagation path estimation section 301 estimates the propagation path between the desired received base station and the desired base station from _Nc subcarriers. The estimated channel value of the _Nc subcarrier with the desired base station is input to the weight calculator 211 and the weight multiplier 303.

Similarly, in the interference signal 1 propagation path estimator 302-1,..., The interference base station J propagation path estimator 302-J, a propagation path between the input received pilot signal and each interference base station is set to each N _c. Estimate in number of subcarriers. N _c subcarrier propagation path estimates between each of the interference base stations 1 to J are input to the weight calculation unit 211 and the weight multiplication unit 306-1 to the weight multiplication unit 306-J, respectively.

The weight calculation unit 211 uses the obtained desired signal propagation path estimated values and the propagation path estimated values from the interference signals 1 to J for each of the N _c subcarriers to compensate for variations in the phase and amplitude of the desired signal. The ZF weight, the MMSE weight, and the like are calculated and input to the weight multiplier 303 and the weight multiplier 306-1 to the weight multiplier 306-J. Weight multiplication section 303 outputs the desired signal propagation path estimation value, which is an input from desired signal propagation path estimation section 301, multiplied by the input from weight calculation section 211 for each subcarrier to despreading section 304. . The despreading unit 304 synthesizes the input N _c values for each frequency block, calculates N _s (= N _c / SF) despread values, and outputs them to the squaring unit 305. Squaring unit 305, by calculating the square of the absolute value for the output of the despreading unit 304, calculates the N _s number of desired signal power, input to the divider 311.

On the other hand, weight multiplication section 306-1 multiplies the input propagation path estimation value of interference signal 1 and the weight input from weight calculation section 211 for each subcarrier, and inputs the result to square section 307-1. The squaring unit 307-1 calculates the interference power of each subcarrier in each interference signal by calculating the square of the absolute values of N _c subcarriers are inputted to the input to the despreader 308-1 . Despreading section 308-1 performs despread processing for each frequency block with respect to the interference power of the interfering signal 1 N _c subcarriers inputted, N _s number of interference power code multiplexing number multiplication unit 309-1 Output to.

In code multiplexing number multiplication section 309-1 multiplies the number of code multiplexing in the interference signal 1 of the data signal, to calculate the N _s number of power of the interference signal 1 is inputted to 1~J synthesis section 310. The above processing is performed for each of the 1 to J interference signals, and the 1 to J combining unit 310 combines the interference power of each interference base station. Then, N _s inter-cell interference power is calculated and input to the division unit 311. The divider 311, the _{N s} number of desired signal power, which is the output of the squaring unit 305, divides each with _{N s} number of inter-cell interference power is the output of 1~J synthesizing section 311, _{N s} symbols The SIR for each is calculated and output.

  The calculated SIR is input to the CQI generation unit 213 shown in FIG. The CQI generation unit 213 determines MCS (error correction coding rate and modulation scheme) that can improve throughput characteristics while satisfying desired communication quality, and notifies the base station of the MCS as CQI. The CQI may include SIR in addition to MCS.

  As described above, according to the communication system according to the first embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At this time, not only the propagation path with the desired base station is estimated, but also the propagation path with the interference base station is estimated. Further, the weight for compensating the propagation path of the desired signal is obtained for each subcarrier by using the propagation path estimated value with each obtained interference base station. By obtaining the inter-cell interference power for each interfering base station and then combining the interference powers, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. Therefore, reception quality such as SIR after despreading and carrier-to-interference wave power ratio (CIR) can be estimated without depending on the pilot correlation between the interfering base stations. As a result, the optimum MCS can be determined in the propagation path for communication, so that the throughput characteristics can be improved.

(Second Embodiment)
In the communication system according to the second embodiment, each base station transmits a pilot signal using different subcarriers, while the mobile station estimates a propagation path of a subcarrier transmitted by each base station. By interpolating between pilot subcarriers, the propagation path is estimated even for subcarriers in which no pilot is transmitted.

  Hereinafter, a base station and a mobile station configuring the communication system according to the second embodiment will be described. The base station and mobile station according to the second embodiment have the same configuration as the base station and mobile station according to the first embodiment, except that the functions of some components are different. Therefore, the following description will focus on components having different functions while referring to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

The base station according to the second embodiment inputs data signals for N _c subcarriers obtained by the same processing as the base station according to the first embodiment to the pilot signal insertion unit 106. Pilot signal generation section 105 generates an FDM (Frequency Division Multiplexing) pilot, and pilot signal insertion section 106 multiplexes the data signal and the pilot signal.

  Here, an example of a frame configuration output from pilot signal insertion section 106 is shown in FIG. In the transmission frame, pilot signals shown at times 1, 6, 11 and the like are transmitted, and data signals are transmitted at other times. The pilot signal constitutes a pilot and a carrier hole so that the pilot transmitted from each base station in the mobile station is orthogonal on the frequency axis. For example, in the transmission frame shown in FIG. 4, since the first, fifth, ninth, etc. subcarriers are used as pilots in each pilot signal, the second, sixth, tenth, etc. subcarriers are used in each pilot signal in other base stations. By using the carrier as a pilot, the pilot from each base station can be orthogonalized in the mobile station.

The output of the pilot signal insertion unit 106 is input to the IFFT unit 107, which performs N _FFT (≧ N _c ) point inverse fast Fourier transform (IFFT) processing to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG. The signal transmitted from the base station is received by the mobile station through the propagation path. In the mobile station, processing similar to that of the mobile station according to the first embodiment is performed, and _Nc subcarriers are obtained in the FFT unit 204. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210.

  Hereinafter, channel estimation between the desired base station and the interference base station in the mobile station according to the second embodiment will be described. First, channel estimation with a desired base station in a mobile station according to the second embodiment will be described. In the mobile station, the pilot signal input to propagation path estimation section 210 is input to desired signal propagation path estimation section 301 shown in FIG. Here, internal processing of desired signal propagation path estimation section 301 when linear interpolation is used as an interpolation method between FDM pilots in a mobile station will be described with reference to FIG.

  As shown in FIG. 5, desired signal propagation path estimation section 301 inputs the received pilot signal to pilot carrier extraction section 501. The pilot carrier extraction unit 501 extracts only the pilot transmitted from the desired base station using the signal input from the pilot signal generation unit 502 and inputs it to the inverse modulation unit 503. Inverse modulation section 503 divides the received pilot from the desired base station by the transmission pilot symbol generated by pilot signal generation section 502 to calculate a channel estimation value for the received pilot, and inputs it to averaging section 504 To do.

  When there are a plurality of FDM pilot signals, the channel estimation values of the respective FDM pilot signals are sequentially stored in the buffer in the averaging unit 504, and the averaging process is performed to improve the accuracy of channel estimation. it can. The channel estimation value after the averaging process is output as the channel estimation value of the subcarrier. Further, a carrier in which no pilot exists, for example, a subcarrier between the averaging unit 504-1 and the averaging unit 504-2 is linearly interpolated using outputs of the averaging unit 504-1 and the averaging unit 504-2. A propagation path estimation value is obtained by the unit 505-1.

For example, assuming that the channel estimation values of subcarriers 1 and 5 shown in FIG. 4 are H (1) and H (5), channel estimation obtained by linear interpolation of the xth subcarrier between subcarriers 1 and 5 The value H (x) is obtained by the following equation.

Based on the above equation, the linear interpolation unit 505-1 performs channel estimation of the carrier between pilots. By performing the same processing for the subcarriers to be interpolated, a desired signal propagation path estimation value of _Nc subcarriers is calculated and output from desired signal propagation path estimation section 301 shown in FIG. For the outer carrier that cannot be interpolated by the pilot, a propagation path estimated value can be obtained by equivalence interpolation or extrapolation processing using the estimated value of the nearest pilot.

  Here, the case where linear interpolation is used as an interpolation method between FDM pilots in a mobile station has been described. However, the present invention is not limited to this. For example, spline interpolation, DCT (Discrete Cosine Transform) interpolation, and sinc function are used. Any polynomial interpolation such as interpolation may be used.

Next, propagation path estimation with the interference base station in the mobile station according to the second embodiment will be described. The pilot signal of the _Nc subcarrier extracted by pilot signal extraction section 205 shown in FIG. 3 is input to interference signal 1 propagation path estimation section 302-1 shown in FIG. Interference signal 1 propagation path estimation section 302-1 performs internal processing in the same manner as the internal processing of desired signal propagation path estimation section 301 shown in FIG.

That is, pilot carrier extraction section 501 extracts only the pilot transmitted from interfering base station 1 using the signal input from pilot signal generation section 502 based on the extracted pilot signal. Then, similarly to the linear interpolation method for the desired signal, the interference signal 1 is also interpolated, and the propagation path estimation value of the interference signal 1 for the _Nc subcarrier is calculated using the weight calculation unit 211 and the weight multiplication unit 306 shown in FIG. Input to -1. When there are J interfering base stations, the same processing as interference signal 1 is performed on each interference signal.

  In addition, since the estimation of the propagation path with the interference base station cannot be as accurate as the estimation of the propagation path with the desired base station, spline interpolation is used to estimate the propagation path of the desired base station. For example, linear interpolation may be used for channel estimation, and a channel estimation method different from the channel estimation method with the desired base station may be used for the channel estimation method with each interfering base station. By using different propagation path estimation methods, the circuit scale in the mobile station can be reduced.

  Further, regarding the interference power, since it is not always necessary to obtain the complex amplitude of the propagation path between the mobile station and each interference station, the amplitude or power of the received pilot signal may be interpolated. That is, when estimating the power of the interference signal, a phase removal unit 601 is prepared as shown in FIG. 6 instead of the inverse modulation unit 503 shown in FIG. Pilot signal generating section 502 notifies pilot carrier extracting section 501 of the carrier in which the pilot exists, and pilot carrier extracting section 501 inputs the received pilot signal to phase removing section 601 only for the carrier in which the pilot exists. The phase removal unit 601 calculates the amplitude or power of the signal and uses it as an input to the linear interpolation unit 505 or a propagation path estimation value in the subcarrier.

The complex channel estimation value of the _Nc subcarrier of the desired signal from the desired signal propagation channel estimation unit 301 shown in FIG. 3 and the interference signal 1 propagation channel estimation unit 302-1 to the interference signal J propagation channel estimation unit 302 -J. The amplitude or power of the propagation path of each _Nc subcarrier is input to the weight calculation unit 211, and the weight calculation unit 211 calculates a weight for propagation path compensation. The output of the complex channel estimation value of the desired signal from the desired signal propagation channel estimation unit 301 and the output from the weight calculation unit 211 are input to the weight multiplication unit 306, and the same processing as in the first embodiment is performed. The signal power is input to the division unit 311.

Further, the amplitude or power of the propagation path of each _Nc subcarrier, which is the output of the interference signal 1 propagation path estimation unit 302-1, and the output of the weight calculation unit 211 are input to the weight multiplication unit 306-1. The same processing as that of the first embodiment is performed, and the interference power of the interference signal 1 is calculated in the code multiplexing number multiplication unit 309-1. When there are J interfering base stations, the same processing as that for the interfering base station 1 is performed on the remaining interference signals. The obtained interference powers for J stations are combined by 1 to J combining section 310 and input to dividing section 311. The division unit 311 calculates the SIR by dividing the desired signal power by the interference signal power.

  As described above, according to the communication system according to the second embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At this time, since the pilot from the desired base station and the pilot from the interfering base station can be completely separated by subcarriers by using the FDM pilot, the pilot is transmitted by interpolating between the pilot subcarriers. It is possible to estimate the propagation path even for carriers that are not. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. As a result, it is possible to estimate reception quality such as despread SIR and carrier-to-interference wave power ratio (CIR), which does not depend on the pilot correlation between the interfering base stations.

(Third embodiment)
In the communication system according to the third embodiment, as in the second embodiment, each base station transmits a pilot signal using different subcarriers, while each mobile station transmits a pilot signal. In addition to estimating the carrier propagation path, interpolation between pilot subcarriers is also performed to estimate the propagation path for subcarriers in which no pilot is transmitted.

  Hereinafter, a base station and a mobile station configuring the communication system according to the third embodiment will be described. The base station and mobile station according to the third embodiment have the same configurations as the base station and mobile station according to the first embodiment, except that the functions of some components are different. Therefore, the following description will focus on components having different functions while referring to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

The base station according to the third embodiment inputs data signals for N _c subcarriers obtained by the same processing as the base station according to the first embodiment to the pilot signal insertion unit 106. Pilot signal generation section 105 generates an FDM (Frequency Division Multiple) pilot, and pilot signal insertion section 106 multiplexes the data signal and the pilot signal.

  The frame configuration output from pilot signal insertion section 106 is the same as the frame configuration according to Embodiment 2 (see FIG. 4). That is, in the transmission frame, pilot signals shown at times 1, 6, 11, etc. are transmitted, and data signals are transmitted at other times. The pilot signal constitutes a pilot and a carrier hole so that the pilot transmitted from each base station in the mobile station is orthogonal on the frequency axis. For example, in the transmission frame shown in FIG. 4, since the first, fifth, ninth, etc. subcarriers are used as pilots in each pilot signal, the second, sixth, tenth, etc. subcarriers are used in each pilot signal in other base stations. By using the carrier as a pilot, the pilot from each base station can be orthogonalized in the mobile station.

The output of the pilot signal insertion unit 106 is input to the IFFT unit 107, which performs N _FFT (≧ N _c ) point inverse fast Fourier transform (IFFT) processing to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG. The signal transmitted from the base station is received by the mobile station through the propagation path. In the mobile station, processing similar to that of the mobile station according to the first embodiment is performed, and _Nc subcarriers are obtained in the FFT unit 204. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210.

  Hereinafter, channel estimation between the desired base station and the interference base station in the mobile station according to the third embodiment will be described. First, propagation path estimation with a desired base station will be described. In the mobile station, the pilot signal input to propagation path estimation section 210 is input to desired signal propagation path estimation section 301 shown in FIG. Here, the internal processing of the desired signal propagation path estimation unit 301 will be described with reference to FIG.

As shown in FIG. 7, the _Nc subcarrier received pilot signal extracted by pilot signal extraction section 205 is input to zero substitution section 701. The zero substitution unit 701 substitutes subcarriers other than the pilot transmitted from the desired base station with zeros based on the information from the pilot signal generation unit 702 and inputs the subcarriers to the inverse modulation unit 703. For example, when an FDM pilot in which pilots are arranged at equal intervals of 4 subcarriers is used, as shown in FIG. 8A, “0” is inserted into subcarriers that do not have a pilot to be estimated.

  In inverse modulation section 703, for the carrier in which the pilot of the desired signal is transmitted, division by the pilot generated by pilot signal generation section 702 calculates the channel estimation value in the subcarrier, and averaging section 704 Output to. Averaging section 704 improves the accuracy of channel estimation by taking a time average when a plurality of pilot signals are transmitted. Averager 704 inputs the averaged propagation path estimated value to IFFT unit 705.

IFFT section 705 performs N _FFT point IFFT processing on the output of the N _c subcarrier from averaging section 704. When N _c <N _FFT , that is, when a guard band is present in the pilot signal, processing for correcting the influence of the guard band may be performed. As shown in FIG. 8B, the IFFT unit 705 outputs a signal in which the propagation path delay profile is repeated four times, and inputs the signal to the window multiplier 706.

The window multiplication unit 706 multiplies the output of N _FFT points of the IFFT unit 705 by a window function to extract a delay profile. An example in the case of multiplying rectangular windows as window functions is shown in FIG. In FIG. 8C, rectangular windows are multiplied, but there are various window functions such as a Hamming window, Hanning window, and exponent window. The output of the _{N FFT} point window multiplier 706, and outputs the channel estimation value of the desired signal in the frequency domain performs FFT processing of _{N FFT} point FFT unit 707. By multiplying the window function by the window multiplying unit 706, the FFT unit 707 outputs a propagation path estimated value of N _FFT points interpolated between pilots as shown in FIG. 8D. Note that the _FFT 707 unit outputs a propagation path estimated value in the _Nc subcarrier used for actual communication from the obtained propagation path estimated value of N _FFT points. The desired signal propagation path estimation value output in this way is input to the weight calculation unit 211 and the weight multiplication unit 303 shown in FIG.

Next, propagation path estimation with the interference base station in the mobile station according to the third embodiment will be described. The pilot signal of the _Nc subcarrier extracted by pilot signal extraction section 205 shown in FIG. 3 is input to interference signal 1 propagation path estimation section 302-1 shown in FIG. Interference signal 1 propagation path estimation section 302-1 performs internal processing in the same manner as desired signal propagation path estimation section 301 shown in FIGS.

That is, interference signal 1 propagation path estimation section 302-1 uses the pilot sequence of interference base station 1 generated by pilot signal generation section 702 for the pilot signal input from pilot signal extraction section 205, The same processing as the desired signal propagation path estimation unit 301 is performed. As a result, the propagation path estimated value of the _Nc subcarrier of the interference base station 1 is obtained. If there are J interfering base stations, the same processing is performed on each signal to obtain channel estimation values for J stations. The estimated channel values with these interference base stations are input to the weight calculator 211 and the weight multiplier 303 shown in FIG.

  In the above-described embodiment, the case where FFT is used is described. However, the present invention is not limited to this. Any of FFT, DFT (Discrete Fourier Transform), and DCT may be used.

  The weight calculation unit 211 and the SIR measurement unit 212 use the propagation path estimated value with the desired base station and the propagation path estimated value with the interference base station of the J station obtained in this way, as in the above-described embodiment. A weight for performing propagation path compensation is calculated, and the SIR is calculated using the weight.

  As described above, according to the communication system according to the third embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, since the pilot from the desired base station and the pilot from the interfering base station can be completely separated by subcarriers by using the FDM pilot, the pilot subcarriers are interpolated using FFT / IFFT processing. By doing so, it is possible to estimate the propagation path even for a carrier for which no pilot is transmitted. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. As a result, it is possible to estimate reception quality such as despread SIR and carrier-to-interference wave power ratio (CIR), which does not depend on the pilot correlation between the interfering base stations.

(Fourth embodiment)
In the communication system according to the fourth embodiment, each base station transmits a pilot signal using different spreading codes, while the mobile station despreads each base station with a spreading code used by each base station. The propagation path between is estimated.

  Hereinafter, a base station and a mobile station constituting the communication system according to the fourth embodiment will be described. The base station and mobile station according to the fourth embodiment have the same configurations as the base station and mobile station according to the first embodiment, except that the functions of some components are different. Therefore, the following description will focus on components having different functions while referring to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

The base station according to the fourth embodiment inputs data signals for N _c subcarriers obtained by the same processing as the base station according to the first embodiment to the pilot signal insertion unit 106. The pilot signal generation unit 105 generates a CDM (Code Division Multiplexing) pilot, and the pilot signal insertion unit 106 multiplexes the data signal and the pilot signal.

  Here, an example of a frame configuration output from pilot signal insertion section 106 is shown in FIG. The transmission frame transmits a pilot signal at times 1, 2, 10, 11, and the like, and transmits a data signal at other times. The pilot signal is spread and transmitted in the time direction using an orthogonal code. For example, the code when the code length is 2 will be described with reference to FIG. When the orthogonal code to be used is {1, -1}, the entire pilot signal multiplied by 1 is transmitted as a pilot signal at time 1. In addition, a signal obtained by multiplying the same pilot signal by −1 is transmitted as a pilot signal at time 2. Other base stations generate pilot signals using orthogonal codes {1, 1}.

The output of the pilot signal insertion unit 106 is input to the IFFT unit 107, which performs N _FFT (≧ N _c ) point inverse fast Fourier transform (IFFT) processing to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG. The signal transmitted from the base station is received by the mobile station through the propagation path. In the mobile station, processing similar to that of the mobile station according to the first embodiment is performed, and _Nc subcarriers are obtained in the FFT unit 204. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210.

  Hereinafter, propagation path estimation between the desired base station and the interference base station in the mobile station according to the fourth embodiment will be described. First, propagation path estimation with a desired base station in a mobile station according to the fourth embodiment will be described. In the mobile station, the pilot signal input to propagation path estimation section 210 is input to desired signal propagation path estimation section 301 shown in FIG.

Here, it is assumed that the desired base station is the base station 1 and the interfering base station is the base station 2. Desired signal propagation path estimation section 301 performs despreading in the time direction using orthogonal code {1, -1} multiplied by base station 1 and the two received pilot signals. When there is no fading time fluctuation while receiving two pilot signals, the pilot signal transmitted from the interfering base station can be orthogonalized by using an orthogonal code, so that the pilot signal is not affected by the interference signal. Can be obtained. Then, the channel estimation value of the _Nc subcarrier can be obtained by performing inverse modulation on the obtained signal with a transmission pilot sequence. The propagation path estimated value of the desired signal thus obtained is input to the weight calculation unit 211 and the weight multiplication unit 303 shown in FIG.

Next, propagation path estimation with the interference base station in the mobile station according to the fourth embodiment will be described. In the propagation path estimation with the interference base station, for example, the interference signal 1 propagation path estimation unit 302-1 performs the same processing as the desired signal propagation path estimation unit 301 using the orthogonal code {1, 1}. The channel estimation value with the interference base station is estimated with _Nc subcarriers. The propagation path estimated value of the desired signal thus obtained is input to the weight calculation unit 211 and the weight multiplication unit 306 shown in FIG.

  The weight calculation unit 211 and the SIR measurement unit 212 use the propagation path estimated value with the desired base station and the propagation path estimated value with the interference base station of the J station obtained in this way, as in the above-described embodiment. A weight for performing propagation path compensation is calculated, and the SIR is calculated using the weight.

  As described above, according to the communication system according to the fourth embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, if a CDM pilot is transmitted, it is possible to estimate the propagation path between each base station by separating the pilot from the desired base station and the pilot from the interfering base station by despreading processing. It becomes. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. As a result, it is possible to estimate reception quality such as despread SIR and carrier-to-interference wave power ratio (CIR), which does not depend on the pilot correlation between the interfering base stations.

  Here, the case where the pilot signal is spread in the time direction is shown, but the present invention is not limited to this, and the pilot signal may be spread in the subcarrier direction within each pilot signal.

(Fifth embodiment)
In the communication system according to the fifth embodiment, each base station transmits a pilot signal with a phase rotation unique to the base station so that the impulse response of each base station can be separated in the mobile station. The impulse response of the base station is extracted, and the propagation path to each base station is estimated based on the impulse response.

  Hereinafter, a base station and a mobile station configuring the communication system according to the fifth embodiment will be described. The base station and mobile station according to the fifth embodiment have the same configurations as the base station and mobile station according to the first embodiment, except that the functions of some components are different. Therefore, the following description will focus on components having different functions while referring to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

Each base station generates a pilot sequence composed of _Nc subcarriers in pilot signal generation section 105 shown in FIG. Here, for convenience of explanation, it is assumed that all subcarriers have the same amplitude and the same phase. In the communication system according to the fifth embodiment, in each base station, as shown in FIG. 10, a pilot sequence is obtained by multiplying a certain pilot sequence by a phase rotation proportional to the subcarrier number unique to each base station. Signal. Then, this pilot signal is input to pilot signal insertion section 106, and data signal and pilot signal are multiplexed.

  Here, an example of a frame configuration output from pilot signal insertion section 106 is shown in FIG. The transmission frame transmits a pilot signal at times 1, 2, 10, 11, and the like, and transmits a data signal at other times. In addition, as shown in FIG. 9, the pilot signal may not have a plurality of consecutive symbols.

The output of the pilot signal insertion unit 106 is input to the IFFT unit 107, which performs N _FFT (≧ N _c ) point inverse fast Fourier transform (IFFT) processing to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG. The signal transmitted from the base station is received by the mobile station through the propagation path. In the mobile station, processing similar to that of the mobile station according to the first embodiment is performed, and _Nc subcarriers are obtained in the FFT unit 204. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210.

  Hereinafter, propagation path estimation between the desired base station and the interference base station in the mobile station according to the fifth embodiment will be described. First, propagation path estimation with a desired base station will be described. In the mobile station, the pilot signal input to propagation path estimation section 210 is input to desired signal propagation path estimation section 301 shown in FIG. Here, the internal processing of the desired signal propagation path estimation unit 301 according to the fifth embodiment will be described with reference to FIG. Here, it is assumed that base station 2 shown in FIG. 10 is a desired base station, and base station 1 and base station 3 shown in FIG. 10 are interference base stations.

Inverse modulation section 1101 divides the input _Nc subcarrier pilot signal for each subcarrier by the pilot sequence generated by pilot signal generation section 1102. Thereafter, when a plurality of pilot signals are received, averaging section 1103 performs averaging processing of each subcarrier, and inputs the value of N _c point to IFFT section 1104. The IFFT unit 1104 performs N _FFT point IFFT processing. In the case of N _c <N _FFT , IFFT processing may be performed after performing processing for correcting the influence of the guard band. As shown in FIG. 12, the IFFT output signal has a delay profile of N _FFT points in which the delay profile of each base station is shifted on the time axis by N _q hours.

The window multiplier 1105 multiplies a window that extracts only the propagation path with the base station 2 that is the desired base station, and corrects the time shifted by N _q , thereby correcting the N with the desired base station. _{An FFT} point delay profile is calculated and output to the FFT unit 1106. The FFT unit 1106 performs FFT of N _FFT points on the delay profile of N _FFT points, and calculates and outputs a propagation path estimated value of N _FFT points. Note that the FFT section 1106 outputs a channel estimation value in the _Nc subcarrier used for actual communication from the obtained channel estimation value of N _FFT points. The desired signal propagation path estimation value obtained in this way is input to the weight calculation unit 211 and the weight multiplication unit 303 shown in FIG.

  In the above description, the case where the pilot signal is obtained by multiplying the phase rotation proportional to the subcarrier number is described. However, the present invention is not limited to this. As long as the delay profile can be separated, the present invention can be applied to a case where a pilot signal is multiplied by a non-proportional phase rotation.

Next, propagation path estimation with the interference base station in the mobile station according to the fifth embodiment will be described. The pilot signal of the _Nc subcarrier extracted by pilot signal extraction section 205 shown in FIG. 3 is input to interference signal 1 propagation path estimation section 302-1 shown in the same figure, and is the same as desired signal propagation path estimation section 301. Internal processing is performed. However, the window multiplier 1105 shown in FIG. 11 multiplies a window that can obtain a delay profile of the propagation path of the interference signal 1. A propagation path estimated value obtained by performing FFT processing on the output of window multiplication section 1105 by FFT section 1106 is input to weight calculation section 211 and weight multiplication section 306-1 shown in FIG.

  Note that the same processing as that performed by the interference base station 1 is performed on the interference base station of the J station to be considered. The propagation path estimation values obtained in this way are input to weight calculation section 211, weight multiplication sections 306-2,..., Weight multiplication section 306-J shown in FIG.

  The weight calculation unit 211 and the SIR measurement unit 212 use the propagation path estimated value with the desired base station and the propagation path estimated value with the interference base station of the J station obtained in this way, as in the above-described embodiment. A weight for performing propagation path compensation is calculated, and the SIR is calculated using the weight.

  As described above, according to the communication system according to the fifth embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, a pilot signal is transmitted so that an impulse response in the mobile station appears by time shift by each base station, and each base station uses a window function that can obtain an impulse response of each base station in the mobile station. The propagation path between is estimated. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. As a result, it is possible to estimate reception quality such as despread SIR and carrier-to-interference wave power ratio (CIR), which does not depend on the pilot correlation between the interfering base stations.

(Sixth embodiment)
In the communication system according to the sixth embodiment, a scattered pilot is transmitted from each base station, and a propagation path is estimated even for subcarriers in which no pilot is transmitted by interpolating between pilot subcarriers in the mobile station. To do.

  Hereinafter, a base station and a mobile station configuring the communication system according to the sixth embodiment will be described. The base station and mobile station according to the sixth embodiment have the same configurations as the base station and mobile station according to the first embodiment, except that the functions of some components are different. Therefore, the following description will focus on components having different functions while referring to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

The base station according to the sixth embodiment inputs data signals for N _c subcarriers obtained by the same processing as the base station according to the first embodiment to the pilot signal insertion unit 106. Pilot signal generation section 105 generates a pilot and inputs it to pilot signal insertion section 106. The pilot signal insertion unit 106 generates a transmission frame so as to have a configuration (scattered pilot) in which pilots are arranged in frequency and time.

Here, a description will be given using a scattered pilot constituting a frame as shown in FIG. Each base station transmits an MC-CDMA signal composed of pilots, carrier holes, and data symbols as shown in FIG. It is assumed that the pilot arrangement is repeated periodically from the 17th subcarrier to the _Ncth subcarrier. At this time, each base station arranges and transmits pilots on different subcarriers in each base station so that the pilots from each base station are orthogonal in the mobile station. That is, assuming that FIG. 13 shows the frame configuration of the base station 1, the frame configuration of the base station 2 is, for example, that the first, 9, 13, 17 subcarriers at time 1 are carrier holes, and the fifth subcarrier is It is a pilot, and other subcarriers are data symbols.

The output of the pilot signal insertion unit 106 is input to the IFFT unit 107, which performs N _FFT (≧ N _c ) point inverse fast Fourier transform (IFFT) processing to obtain N _FFT time signals. The guard interval (GI) adding unit 108 copies the rear part of the signal after IFFT by T _GI and pastes it at the head of the N _{FFT FFT} outputs. And it transmits with the antenna part 110 via the wireless transmission part 109. FIG. The signal transmitted from the base station is received by the mobile station through the propagation path. In the mobile station, processing similar to that of the mobile station according to the first embodiment is performed, and _Nc subcarriers are obtained in the FFT unit 204. Thereafter, the received pilot signal is extracted by pilot signal extraction section 205 and input to propagation path estimation section 210.

  Hereinafter, propagation path estimation between the desired base station and the interference base station in the mobile station according to the sixth embodiment will be described. First, propagation path estimation with a desired base station in a mobile station according to the sixth embodiment will be described. In the mobile station, the pilot signal input to propagation path estimation section 210 is input to desired signal propagation path estimation section 301 shown in FIG.

For example, when the desired base station transmits in the frame configuration shown in FIG. 13, the mobile station estimates the propagation path in the pilot by dividing the received pilot by the transmission pilot. In this case, as described in the second embodiment, linear interpolation is performed on the propagation path estimation values of the first and 17th subcarriers at time 1, and the propagation path estimations of the 17th and 33rd subcarriers are further performed. By performing linear interpolation on the values, it is possible to obtain channel estimation values for all _Nc subcarriers. Alternatively, as described in the third embodiment, after substituting subcarriers other than the pilots such as the first, 17th, and 33rd at time 1 to zero, interpolation using FFT / IFFT is performed, so that all N You may obtain the propagation path estimated value in _c subcarrier. Further, the propagation path estimated value may be averaged in the time direction. The propagation path estimation value with the desired base station obtained in this way is input to the weight calculation unit 211 and the weight multiplication unit 303 shown in FIG.

  In the two-dimensional interpolation method between the time direction and the frequency direction, the interpolation in the frequency direction may be performed as described above, and then the interpolation in the time direction may be performed. Interpolation in the frequency direction may be performed using the channel estimation value obtained by the above. Further, different interpolation methods may be used.

Next, propagation path estimation with the interference base station in the mobile station according to the sixth embodiment will be described. Note that the interference base station also estimates the _Nc subcarrier propagation path to each interference base station by inputting the output of the pilot signal extraction section 205 shown in FIG. 2 to the propagation path estimation section 210. Is possible. The propagation path estimated value with the interference base station obtained in this way is input to the weight calculation unit 211 and the weight multiplication unit 303 shown in FIG.

  The weight calculation unit 211 and the SIR measurement unit 212 use the propagation path estimated value with the desired base station and the propagation path estimated value with the interference base station of the J station obtained in this way, as in the above-described embodiment. A weight for performing propagation path compensation is calculated, and the SIR is calculated using the weight. Note that a different MMSE weight may be obtained for each MC-CDMA symbol, or the same MMSE weight may be used for each MC-CDMA symbol.

  As described above, according to the communication system according to the sixth embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, a scattered pilot is transmitted from each base station, and the propagation path can be estimated even for subcarriers in which the pilot is not transmitted by interpolating between pilots in the mobile station. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. As a result, it is possible to estimate reception quality such as SIR and carrier-to-interference wave power ratio (CIR), which does not depend on pilot correlation between interfering base stations.

(Seventh embodiment)
In the communication systems according to the first to sixth embodiments described above, a case where only inter-cell interference is used as an interference has been described. However, in the communication system according to the seventh embodiment, an inter-cell interference is described. The communication system according to the first to sixth embodiments is different from the first to sixth embodiments in that factors other than interference are taken into consideration.

  The base station according to the seventh embodiment has the same configuration as the base station according to the first embodiment, except that the functions of some components are different. The mobile station according to the seventh embodiment includes the noise power estimation unit, and the SIR measurement unit 212 is the same as that of the first embodiment except that the SINR is calculated in consideration of other interference and thermal noise. It has the same configuration as the mobile station. For this reason, the following description will focus on the differences with reference to the configurations of the base station shown in FIG. 1 and the mobile stations shown in FIGS.

  Hereinafter, the SIR calculation method in the communication system according to the seventh embodiment will be described. Here, it is assumed that an FDM pilot is used in pilot signal generation section 105 shown in FIG. Further, it is assumed that there is no interference other than inter-cell interference, and the average power of noise in each subcarrier is constant. FIG. 14 is a diagram for explaining the SIR calculation method in the communication system according to the seventh embodiment. In FIG. 14, the same components as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.

  The pilot signal extracted by the pilot signal extraction unit 205 is added to the desired signal propagation path estimation unit 301, the interference signal 1 propagation path estimation unit 302-1, ..., the interference base station J propagation path estimation unit 302-J, It is input to the noise power estimation unit 1401. Here, the configuration of the noise power estimation unit 1401 will be described. FIG. 15 is a block diagram illustrating an example of the configuration of the noise power estimation unit 1401 according to the seventh embodiment.

  As illustrated in FIG. 15, the noise power estimation unit 1401 includes a propagation path estimation unit 1501, a pilot signal generation unit 1502, a remodulation unit 1503, a subtraction unit 1504, a square unit 1505, and an averaging unit 1506. Propagation path estimation section 1501 performs propagation path estimation of a desired signal using a pilot signal generated by pilot signal generation section 1502 in a subcarrier where a pilot is transmitted from the desired base station, and outputs a propagation path estimated value To do.

  Remodulation section 1503 generates a pilot replica by multiplying the propagation path estimation value in the subcarrier output from propagation path estimation section 1501 using the pilot signal and the pilot generated by pilot signal generation section 1502 To do. Subtraction section 1504 calculates and outputs a noise component in the subcarrier by subtracting the output from remodulation section 1503 from the received pilot signal output from pilot extraction section 205 for the subcarrier. The square unit 1505 obtains the noise power of the subcarrier by calculating the square of the absolute value of the input noise component.

Note that propagation path estimation section 1501, pilot signal generation section 1502, remodulation section 1503, subtraction section 1504, and squaring section 1505 perform the same processing for subcarriers from which pilots are transmitted from interfering base stations. Thereby, the noise power of the subcarrier is obtained. The _Nc subcarrier noise power calculated using the pilots from the desired base station and the interference base station in this way is input to averaging section 1506. Averaging section 1506 obtains the average noise power by performing averaging processing on _Nc subcarriers.

  The output of the noise power estimation unit 1401 is input to the multiplication unit 1402 in the SIR measurement unit 212 as shown in FIG. Note that the noise power obtained by the noise power estimation unit 1401 may be input to the weight calculation unit 211 and used as a weight for compensating the propagation path of the desired signal.

In SIR measurement section 212, squaring section 1403 calculates the square of the absolute value of the _Nc subcarrier weight output from weight calculation section 211 for each subcarrier, and outputs the square to despreading section 1404. The despreading unit 1404 despreads the square value of the weight input for each spread frequency block and outputs the despread N _s values to the multiplication unit 1402. Multiplying section 1402 multiplies N _s values from the despreading section and the average power of noise that is output from noise power estimation section 1401, and the obtained N _s values are interference noise synthesis section 1405. Output to.

In interference noise synthesis unit 1405 synthesizes the N _s number of interference power interfering base station is input from the 1~J synthesis unit 310 is an input from the multiplication unit 1402 N _s number of the noise power, respectively, The result is output to the division unit 311. The division unit 311 calculates N _s SINR considering noise by dividing the N _s desired signal power from the square unit 305 by the N _s interference + noise power from the multiplication unit 1402. To do.

  Although only an example of thermal noise power estimation is described here, the SIR measurement unit 212 performs inter-code interference when code multiplexing is performed, and symbol interference when a delayed wave exceeding the guard interval exists. Alternatively, a circuit for calculating interference or thermal noise due to a carrier frequency offset may be added and combined by the interference noise synthesis unit 1405 to calculate the SINR. In this case, it is possible to create a CQI based on SINR considering not only inter-cell interference but also other interference and noise, and notify the base station.

  As described above, according to the communication system according to the seventh embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, not only the propagation path with the desired base station is estimated, but also the propagation path with the interference base station is estimated. Further, the weight for compensating the propagation path of the desired signal is obtained for each subcarrier by using the propagation path estimated value with each obtained interference base station. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. Therefore, reception quality such as SIR after despreading and carrier-to-interference wave power ratio (CIR) can be estimated without depending on the pilot correlation between the interfering base stations.

  Particularly, according to the communication system according to the seventh embodiment, not only the inter-cell interference power but also other interference power and noise power are estimated, and a circuit that combines with the inter-cell interference power is incorporated into the SIR estimation unit 430. Therefore, SINR with higher accuracy can be obtained. As a result, the optimum MCS can be determined in the propagation path for communication, so that the throughput characteristics can be improved.

(Eighth embodiment)
In the communication system according to the eighth embodiment, a case where the present invention is adapted to a scheduling system will be described. The frequency resource is composed of several frequency blocks, and symbols are spread within each frequency block. In each mobile station, the despread SIR measured by the SIR measurement unit 212 shown in FIG. 2 is input to the CQI generation unit 213, and the CQI generation unit 213 generates the CQI and notifies the desired base station. The base station compares the CQI of each mobile station for each frequency block, and assigns the frequency block to the mobile station that has notified the highest CQI. This process is performed for each frequency block.

  In the base station, the information bits of the terminal to which the frequency block is assigned are encoded by the control signal from the adaptive modulation section 111, and modulated by the modulation scheme based on the control signal from the adaptive modulation section 111. The mobile station can perform high-speed data transmission while maintaining desired reception quality by performing demodulation using the error correction coding rate and modulation scheme transmitted by the base station.

  Here, the case where Max CIR is used as the scheduling method has been described. However, the present invention is not limited to this, and other known scheduling methods such as proportional fairness and roundrobin also relate to the present invention. A SIR estimation method can be applied.

  In the mobile station, the CQI generation unit 213 generates CQI based on the SINR measured by the SIR measurement unit 212 shown in FIG. 2, and notifies the desired base station. Various techniques such as Top-M and DCT have been proposed as methods for limiting the number of CQI bits in this case, but the present invention can be applied to any technique.

  As described above, according to the communication system according to the eighth embodiment, the interference using the weight for compensating the propagation path of the desired signal and the obtained propagation path estimated value between each interference base station. Inter-cell interference power can be obtained by individually estimating and combining the interference power from the base station. At that time, not only the propagation path with the desired base station is estimated, but also the propagation path with the interference base station is estimated. Further, the weight for compensating the propagation path of the desired signal is obtained for each subcarrier by using the propagation path estimated value with each obtained interference base station. Then, by obtaining the inter-cell interference power for each interfering base station, the inter-cell interference power that does not depend on the pilot correlation between the interfering base stations can be calculated. Therefore, reception quality such as SIR after despreading and carrier-to-interference wave power ratio (CIR) can be estimated without depending on the pilot correlation between the interfering base stations. Furthermore, the system throughput can be greatly improved by using a transmission technique such as scheduling that needs to use the received SIR.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. These modified examples contribute to the practical application of next-generation cellular systems. Further, the present invention is not limited to the above-described embodiment, and can be appropriately changed within a range in which the effects of the present invention are exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

It is a block diagram which shows an example of a structure of the base station which comprises the communication system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows an example of a structure of the mobile station which comprises the communication system which concerns on 1st Embodiment. It is the figure which showed in detail about the pilot signal extraction part in FIG. 2, a propagation path estimation part, a weight calculation part, and a SIR measurement part. It is a figure which shows an example of the frame structure output from the pilot signal insertion part of the base station which concerns on 2nd Embodiment. It is a figure for demonstrating the internal process of the desired signal propagation path estimation part of the mobile station which concerns on 2nd Embodiment. It is a figure for demonstrating the other internal process of the desired signal propagation path estimation part of the mobile station which concerns on 2nd Embodiment. It is a figure for demonstrating the internal process of the desired signal propagation path estimation part of the mobile station which concerns on 3rd Embodiment. It is a figure which shows an example of the FDM pilot output from the base station which concerns on 3rd Embodiment. It is a figure which shows an example of the frame structure output from the pilot signal insertion part of the base station which concerns on 4th Embodiment. It is a figure which shows an example of the pilot series output from the base station which concerns on 5th Embodiment. It is a figure for demonstrating the internal process of the desired signal propagation path estimation part which concerns on 5th Embodiment. It is a figure which shows an example of the output signal from the IFFT process part of the mobile station which concerns on 5th Embodiment. It is a figure which shows an example of the flame | frame structure output from the pilot signal insertion part of the base station which concerns on 6th Embodiment. It is a figure for demonstrating the SIR calculation method in the communication system which concerns on 7th Embodiment. It is a block diagram which shows an example of a structure of the noise power estimation part which concerns on 7th Embodiment. It is a figure which shows the internal structure of the base station which comprises the conventional radio | wireless communications system. It is a figure which shows the internal structure of the mobile station which comprises the conventional radio | wireless communications system. It is a figure for demonstrating the calculation method of SIR in the conventional radio | wireless communications system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Error correction coding part 102 Mapping part 103 Spreading part 104 Code multiplexing part 105 Pilot signal generation part 106 Pilot signal insertion part 107 IFFT part 108 GI addition part 109 Radio transmission part 110 Antenna part 201 Antenna part 202 Radio reception part 203 GI removal Unit 204 FFT unit 205 pilot signal extraction unit 206 propagation path compensation unit 207 despreading unit 208 de-mapping unit 209 error correction decoding unit 210 propagation channel estimation unit 211 weight calculation unit 212 SIR measurement unit 213 CQI generation unit 301 desired signal propagation channel Estimation unit 302 Interference signal propagation path estimation unit 303 Weight multiplication unit 304 Despreading unit 305 Squared unit 306 Weight multiplication unit 307 Squared unit 308 Despreading unit 309 Code multiplexing number multiplication unit 310 1 to J synthesis unit 311 Division unit 501 Pilot Carrier extraction unit 50 Pilot signal generation section 503 Inverse modulation section 504 Averaging section 505 Linear interpolation section 601 Phase removal section 701 Zero substitution section 702 Pilot signal generation section 703 Inverse modulation section 704 Averaging section 705 IFFT section 706 Window multiplication section 707 FFT section 1101 Inverse modulation Unit 1102 pilot signal generation unit 1103 averaging unit 1104 IFFT unit 1105 window multiplication unit 1106 FFT unit 1401 noise power estimation unit 1402 multiplication unit 1403 square unit 1404 despreading unit 1405 interference noise synthesis unit 1501 propagation path estimation unit 1502 pilot signal generation Part 1503 remodulation part 1504 subtraction part 1505 square part 1506 averaging part

Claims (10)

A receiver that performs multicarrier communication with a transmitter,
A pilot extraction unit that extracts a first pilot signal transmitted from the first transmission device and a second pilot signal transmitted from one or more second transmission devices other than the first transmission device;
A first propagation path estimation value for each subcarrier for the first transmitter is calculated from the first pilot signal, while a second for each subcarrier for the second transmitter is calculated from the second pilot signal. A propagation path estimator for calculating a propagation path estimated value of
A weight calculator for calculating a weight for each subcarrier from at least the first propagation path estimated value;
A reception apparatus comprising: a reception quality measurement unit that measures reception quality of a data signal from the first and second propagation path estimation values and the weights. The pilot extraction unit extracts the first and second pilot signals transmitted by using pilot subcarriers different from each other,
The propagation path estimation unit uses the first and second pilot signals to estimate a propagation path in a subcarrier to which the first transmission device has transmitted a pilot, and uses the propagation path estimation value to While the first transmission device estimates the propagation channel in the subcarrier that did not transmit the pilot, the first propagation channel estimation value is calculated, while the second transmission device transmits the pilot in the subcarrier. Estimating the path and calculating the second propagation path estimated value by estimating the propagation path in the subcarrier in which the second transmitting apparatus did not transmit the pilot using the propagation path estimated value. The receiving device according to claim 1. The pilot extraction unit uses a spreading code to spread the first pilot signal that is spread and transmitted in at least one of the time direction and the frequency direction and a spreading code that is different from the first pilot signal. Extracting the transmitted second pilot signal;
The propagation path estimation unit calculates the first propagation path estimated value by performing despreading on the first and second pilot signals with a spreading code used for the first pilot signal. The receiving apparatus according to claim 1, wherein the second propagation path estimated value is calculated by performing despreading with a spreading code used for the second pilot signal. The pilot extraction unit is different from the first pilot signal transmitted by applying phase rotation to the pilot symbol for each subcarrier, and the first pilot signal so that the impulse response of the propagation path can be separated in the apparatus main body. Extracting a second pilot signal to be transmitted by applying phase rotation to the pilot symbols;
The propagation path estimation unit converts the first and second pilot signals into a time domain, extracts a first propagation path impulse response with respect to the first transmission device, and converts the impulse response into a frequency domain. While calculating the first propagation path estimated value, the second propagation path impulse response to the second transmission device is extracted, and the impulse response is converted into the frequency domain to convert the second propagation path. The receiving apparatus according to claim 1, wherein an estimated value is calculated.   The receiving apparatus according to claim 1, wherein a method for calculating the first propagation path estimation value in the propagation path estimation unit is different from a method for calculating the second propagation path estimation value.   The propagation path estimation unit estimates the phase and amplitude in the first propagation path for the first transmission apparatus, and estimates only the power in the second propagation path for the second transmission apparatus, The receiving device according to claim 5. A further interference power measuring unit for obtaining power of other interference that is interference other than the signal transmitted from the second transmission device;
The weight calculation unit calculates a weight for each subcarrier based on the power of the other interference,
The reception quality measurement unit calculates a total interference power based on the power of the signal transmitted from the second transmission device and the power of the other interference, and receives the reception quality of the data signal based on the total interference power The receiver according to any one of claims 1 to 6, wherein the receiver is measured. A transmission device that performs multicarrier communication with a reception device,
A transmitter that transmits a first pilot signal and a transmission frame to the receiver;
Based on the first propagation path estimated value estimated from the receiving device based on the first pilot signal and the second pilot signal transmitted from one or more second transmitting devices other than the transmitting device. A receiving unit that receives a signal indicating reception quality measured using the second propagation path estimation value estimated in step S1 and a weight calculated based on at least the first propagation path estimation value;
A transmission parameter determination unit that determines a transmission parameter including at least one of a spreading factor, a code multiplexing number, a modulation scheme, and a coding rate based on the reception quality;
A transmission frame generating unit configured to generate the transmission frame based on the determined transmission parameter. A communication system for performing multicarrier communication between a transmission device and a reception device,
The receiving device extracts a first pilot signal transmitted from the transmitting device and a second pilot signal transmitted from one or more other transmitting devices other than the transmitting device, and the first pilot signal Calculating a first propagation path estimated value for each subcarrier for the transmitting apparatus from the second pilot signal, and calculating a second propagation path estimated value for each subcarrier for the other transmitting apparatus from at least Calculating a weight for each subcarrier from the first propagation path estimated value, measuring a reception quality of the data signal from the first and second propagation path estimated values and the weight,
The transmitter transmits the first pilot signal to the receiver, while receiving a signal indicating the reception quality from the receiver, and based on the reception quality, a spreading factor, a code multiplexing number, and a modulation A communication system characterized by determining a transmission parameter including at least one of a scheme and a coding rate, and generating a transmission frame based on the transmission parameter. A reception quality measurement method in a communication system for performing multicarrier communication between a transmission device and a reception device,
The receiving device extracts the first pilot signal transmitted from the transmitting device and the second pilot signal transmitted from one or more other transmitting devices other than the transmitting device, and the first pilot signal Calculating a first propagation path estimated value for each subcarrier for the transmitting apparatus from the second pilot signal, and calculating a second propagation path estimated value for each subcarrier for the other transmitting apparatus from at least A reception quality measurement, wherein a weight for each subcarrier is calculated from the first propagation path estimation value, and a reception quality of the data signal is measured from the first and second propagation path estimation values and the weight. Method.

Images