JP4291669B2 - Multi-carrier communication apparatus and multi-carrier communication method - Google Patents

Description

  The present invention relates to a multicarrier communication apparatus and a multicarrier communication method, and more particularly to a multicarrier communication apparatus and a multicarrier communication method that perform multiantenna transmission.

  In recent years, in mobile communication, in order to realize high-speed transmission by effectively using limited frequency resources, multi-carrier modulation schemes and multi-antenna transmission have attracted attention. Furthermore, it has been studied to improve the frequency utilization efficiency by combining these two technologies (see, for example, FIG. 4 of Patent Document 1).

  As multi-antenna transmission for transmitting data using a plurality of antennas, MIMO (Multi-Input Multi-Output) and STC (Space-Time Coding) are known. In MIMO and STC, the same frequency and the same spreading code are used for different data streams and transmitted from a plurality of transmission antennas at the same time. These signals are superimposed on the propagation path and received by the receiving device.

  On the other hand, the multi-carrier modulation scheme improves data transmission efficiency by transmitting data using multiple carriers (subcarriers) whose transmission speed is suppressed to the extent that frequency selective fading does not occur. It is a technology that enables transmission. In particular, the OFDM (Orthogonal Frequency Division Multiplex) modulation scheme is the scheme with the highest frequency utilization efficiency among the multi-carrier modulation schemes because a plurality of subcarriers in which data is arranged are orthogonal to each other. The OFDM modulation scheme can be realized with a relatively simple hardware configuration. For this reason, various studies have been conducted on the OFDM modulation scheme.

  As described above, in multicarrier modulation schemes such as the OFDM modulation scheme, parallel transmission using a plurality of subcarriers is performed. At this time, if the phases of the subcarriers are aligned, a significantly large transmission peak power is generated as compared with the average transmission power. In such a case, it is necessary to use a transmission power amplifier capable of maintaining output linearity over a wide dynamic range. However, in general, such an amplifier has low efficiency and increases power consumption of the apparatus.

Therefore, for example, a method may be employed in which transmission power equal to or higher than a threshold is suppressed by a limiter and transmission peak power is suppressed (see, for example, FIG. 1 of Patent Document 2). A transmission peak power suppression method using partial sequence transmission called PTS (Partial Transmit Sequences) is also known. In PTS, a group of a plurality of subcarriers is formed, an inverse Fourier transform process is performed for each group, and a different phase coefficient is multiplied. Then, the outputs of all groups are added, and a sequence of phase coefficients is selected so that the peak power of the obtained signal is the lowest. Further, side information for notifying the receiving side of the selected phase coefficient series is transmitted, and on the receiving side, the phase is reversely rotated based on the side information, and the data is demodulated (for example, Non-Patent Document 1). reference).
JP 2002-44051 A JP 2002-44054 A Electronics Letters, Volume: 33, Issue: 5, 1997, “OFDM with reduced peak-to-average power ratio by optimum combination of partial transmit sequences”, Muller, SH; Huber, JB

  However, when non-linear processing is performed using, for example, a limiter in order to suppress transmission peak power in multicarrier modulation, generally, inter-subcarrier interference increases due to non-linear distortion, resulting in degradation of characteristics and out of band. There is a problem that unnecessary radiation increases and interferes with signals outside the band. In addition, when PTS is used, there is a problem that the amount of side information different from the information that should be transmitted increases, and transmission efficiency decreases. These problems also occur when combining multi-antenna transmission and multi-carrier modulation schemes.

  The present invention has been made in view of this point, and in wireless communication that performs multi-antenna transmission, a multi-transmission capable of suppressing transmission peak power without causing nonlinear distortion and without reducing transmission efficiency. It is an object of the present invention to provide a carrier communication device and a multicarrier communication method.

  The multicarrier communication apparatus of the present invention is a multicarrier communication apparatus that simultaneously transmits a plurality of different data streams from a plurality of antennas using the same carrier group, and whether or not peak power is generated in at least one data stream. And a switching means for exchanging a part of data of the data stream with a part of data of another data stream when it is determined that peak power is generated.

  According to this configuration, when there is a data stream in which peak power is generated, a carrier for transmitting each data stream is exchanged for exchanging a part of the data of the data stream with a part of the data of another data stream. The phase of the signal changes, non-linear distortion does not occur, and the transmission peak power can be suppressed without reducing the transmission efficiency.

  In the multicarrier communication apparatus of the present invention, the determination unit includes a measurement unit that measures the power of each data stream, and a comparison unit that compares the measured power with a predetermined threshold. A configuration is adopted in which it is determined that peak power is generated in a data stream in which the generated power is not less than a predetermined threshold.

  According to this configuration, since it is determined that the peak power is generated when the measured power of the data stream is equal to or greater than the predetermined threshold, the generation of the peak power in each data stream can be accurately detected.

  In the multicarrier communication apparatus of the present invention, the exchange means determines a pattern for exchanging a part of data of each data stream in units of a predetermined carrier group, and the determined exchange pattern And a data exchange unit for exchanging a part of the data of each data stream.

  According to this configuration, data is exchanged according to an exchange pattern determined in units of carriers, so that an exchange pattern that has a high effect of suppressing transmission peak power can be selected.

  The multicarrier communication apparatus of the present invention employs a configuration in which the exchange pattern determining unit determines a pattern for exchanging data between groups having the same frequency among the groups of carriers.

  According to this configuration, since data is exchanged between groups having the same frequency, even if pilot data included in the data is exchanged, the communication partner station can separate each data stream without information on the data exchange pattern. Can do.

  The multicarrier communication apparatus of the present invention employs a configuration in which the exchange pattern determining unit determines a pattern for exchanging data between groups having different frequencies among the groups of carriers.

  According to this configuration, since data is exchanged between groups having different frequencies, data exchange can be performed more freely, and an exchange pattern with a high effect of suppressing transmission peak power can be selected.

  The multicarrier communication apparatus of the present invention employs a configuration in which the data exchange unit exchanges orthogonal pilot data included in a part of data of each data stream.

  According to this configuration, since data is exchanged including orthogonal pilot data, the communication partner station can perform propagation path estimation without information on the data exchange pattern and separate each data stream.

  The multicarrier communication apparatus of the present invention employs a configuration in which the data exchange unit does not exchange orthogonal pilot data included in a part of data of each data stream.

  According to this configuration, since orthogonal pilot data is not included in data exchange, data of carriers having different frequencies can be exchanged. As a result, data exchange can be performed more freely and transmission peak power is suppressed. A highly effective exchange pattern can be selected.

  The multicarrier communication apparatus of the present invention employs a configuration in which the exchange means includes transmission means for transmitting exchange pattern information for notifying a communication partner station of a pattern for exchanging data.

  According to this configuration, since the exchange pattern information is transmitted to the communication partner station, the exchange can be performed more freely by only transmitting the side information with a small amount of information, and the exchange is highly effective in suppressing the transmission peak power. A pattern can be selected.

  The multicarrier communication apparatus of the present invention employs a configuration in which the transmission means transmits exchange pattern information using a specific carrier excluded from exchange targets.

  According to this configuration, since the exchange pattern information is transmitted using a specific carrier excluded from the exchange target, the communication partner station can reliably extract the exchange pattern information without any special information.

  The multi-carrier communication apparatus of the present invention further includes forming means for forming different directivity weights for each data stream, and the forming means responds when data is exchanged by the exchange means. A configuration in which directional weights are exchanged is adopted.

  According to this configuration, since different directivity weights are formed for each data stream, the correlation of the propagation path environment can be removed for each data stream, and the communication capacity can be improved.

  The multicarrier communication apparatus of the present invention employs a configuration that further includes generating means for encoding transmission data and generating a plurality of different data streams that are in an encoding relationship with each other.

  According to this configuration, in order to encode transmission data and generate a plurality of different data streams having an encoding relationship with each other, for example, space-time coding (STC) and space frequency coding (SFC) Transmission peak power can be suppressed in multi-antenna transmission such as Frequency Coding.

  In the multicarrier communication apparatus of the present invention, the generation means performs block coding of transmission data for each predetermined block coding unit, and the exchange means exchanges data using the block coding unit as a minimum unit. take.

  According to this configuration, since the data exchange is performed with the block coding unit as the minimum unit, it is assumed that the data exchange and the block coding unit coincide with each other, and that the propagation path characteristics regarding consecutive symbols hardly change. The communication partner station can correctly perform the block decoding process.

  The multicarrier communication apparatus of the present invention employs a configuration in which the generation means generates a plurality of different data streams by convolutionally encoding transmission data.

  The multicarrier communication apparatus of the present invention employs a configuration in which the generation means generates a plurality of different data streams by turbo-encoding transmission data.

  According to these configurations, transmission peak power can be suppressed in multi-antenna transmission such as space-time coding and space frequency coding.

  The communication terminal device of the present invention adopts a configuration having any of the multicarrier communication devices described above.

  According to this configuration, the same effect as that of any of the multicarrier communication apparatuses described above can be realized in the communication terminal apparatus.

  The base station apparatus of the present invention employs a configuration having any of the multicarrier communication apparatuses described above.

  According to this configuration, the base station apparatus can achieve the same effect as that of any of the multicarrier communication apparatuses described above.

  The multicarrier communication method of the present invention is a multicarrier communication method for simultaneously transmitting a plurality of different data streams from a plurality of antennas using the same carrier group, and whether or not peak power is generated in at least one data stream. And a step of exchanging a part of data of the data stream with a part of data of another data stream when it is determined that peak power is generated.

  According to this method, when there is a data stream in which peak power is generated, a carrier for transmitting each data stream is exchanged for exchanging a part of the data of the data stream with a part of the data of another data stream. The phase of the signal changes, non-linear distortion does not occur, and the transmission peak power can be suppressed without reducing the transmission efficiency.

  According to the present invention, in wireless communication that performs multi-antenna transmission, non-linear distortion is not caused, and transmission peak power can be suppressed without reducing transmission efficiency.

  In the multicarrier communication apparatus that performs multi-antenna transmission, the inventor has different data stream contents for each transmission antenna, and the transmission peak power of each antenna changes by exchanging a part of the data stream between the transmission antennas. It came to make this invention paying attention to doing.

  That is, the gist of the present invention is to exchange a part of a data stream between transmission antennas so that the transmission peak power is equal to or less than a preset threshold value.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, an OFDM modulation scheme will be described as an example of a multicarrier modulation scheme. That is, the case where the transmitted multicarrier signal is an OFDM symbol will be described.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 1 of the present invention. A multicarrier communication apparatus shown in FIG. 1 includes a demultiplexer 100, S / P (Serial / Parallel) conversion units 110-1 to 110-n (n is a natural number of 2 or more), a data exchange unit 120, an IFFT (Inverse Fast Fourier Transform (Inverse Fast Fourier Transform) units 130-1 to n, P / S (parallel / serial) conversion units 140-1 to 140-n, GI (Guard Interval) insertion units 150-1 to 150-n, power measurement Units 160-1 to 160-n, wireless transmission units 170-1 to 170-n, transmission antennas 180-1 to 180-n, and an exchange pattern determination unit 190. This multicarrier communication apparatus performs MIMO transmission. In other words, different data are transmitted simultaneously from the transmitting antennas 180-1 to 180-n using the same frequency and the same spreading code.

  The demultiplexer 100 divides the transmission data into a plurality (n) of data streams.

  The S / P converters 110-1 to 110-n perform S / P conversion on each data stream, and generate parallel data for the number of subcarriers.

  Based on the control information output from the exchange pattern determination unit 190, the data exchange unit 120 replaces a part of parallel data corresponding to each data stream with a part of parallel data corresponding to another data stream. At this time, the data exchanging unit 120 replaces the parallel data with those of other data streams in units of groups formed by a predetermined number of parallel data. Since each parallel data corresponds to a subcarrier, a group serving as a unit of data replacement is hereinafter referred to as a “subcarrier group” or simply “group”.

  The IFFT units 130-1 to 130-n perform IFFT processing on the parallel data output from the data exchange unit 120, and arrange the data on subcarriers. That is, IFFT sections 130-1 to 130-n perform IFFT processing on parallel data after data is exchanged in units of subcarriers.

  P / S conversion sections 140-1 to 140-n perform P / S conversion on the data of each subcarrier output from IFFT sections 130-1 to 130-n to generate OFDM symbols.

  The GI insertion units 150-1 to 150-n insert guard intervals into the OFDM symbols of each data stream.

  The power measuring units 160-1 to 160-n measure the power of OFDM symbols of each data stream and compare it with a predetermined threshold value. In addition, when the power of the OFDM symbol is equal to or lower than a predetermined threshold as a result of the comparison, the power measuring units 160-1 to 160-n output the OFDM symbol to the wireless transmission units 170-1 to 170-n, and the power of the OFDM symbol is If it is equal to or greater than the predetermined threshold, the power measurement result of each OFDM symbol is output to exchange pattern determining section 190.

  Radio transmitting sections 170-1 to 170-n perform radio transmission processing such as D / A conversion and up-conversion on the OFDM symbols, and transmit from transmitting antennas 180-1 to 180-n.

  The exchange pattern determination unit 190 determines an exchange pattern for exchanging data of the data stream in which the power measured in the power measurement units 160-1 to 160-n is equal to or greater than a predetermined threshold in units of subcarriers. To the data exchange unit 120. A specific example of the exchange pattern will be described later.

  FIG. 2 is a block diagram showing a configuration of the receiving-side multicarrier communication apparatus according to Embodiment 1. The multicarrier communication apparatus shown in FIG. 2 includes receiving antennas 200-1 to 200-n, radio receiving units 210-1 to 210-n, GI removing units 220-1 to 220-n, S / P converters 230-1 to 230-n, FFT (Fast (Fourier Transform: Fast Fourier Transform) sections 240-1 to 240-n, data separation section 250, demodulation sections 260-1 to n, P / S conversion sections 270-1 to 270-n, multiplexer 280, and propagation path estimation section 290 ing.

  Radio receiving sections 210-1 to 210-n receive OFDM symbols from receiving antennas 200-1 to 200-n, and perform radio reception processing such as down-conversion and A / D conversion.

  GI removal sections 220-1 to 220-n remove guard intervals from the OFDM symbols received from the receiving antennas 200-1 to 200-n.

  S / P converters 230-1 to 230-n perform S / P conversion on the OFDM symbols of each data stream, and generate parallel data for the number of subcarriers.

  The FFT units 240-1 to 240-n perform FFT processing on the parallel data of each data stream, and generate data for each subcarrier.

  Based on the propagation path estimation result output from propagation path estimation section 290, data separation section 250 converts the data for each subcarrier into a data stream corresponding to transmission antennas 180-1 to 180-n in the transmission-side multicarrier communication apparatus. To separate.

  Demodulation sections 260-1 to 260-n demodulate each data stream based on the propagation path estimation result output from propagation path estimation section 290.

  The P / S conversion units 270-1 to 270-n perform P / S conversion on the demodulation results output from the demodulation units 260-1 to 260-n, and generate serial data.

  The multiplexer 280 multiplexes the serial data of each data stream to obtain received data.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described with reference to the flowchart shown in FIG. The operation of the reception-side multicarrier communication apparatus (FIG. 2) in the present embodiment is the same as the operation of the conventional multicarrier communication apparatus, and thus the description thereof is omitted.

  First, the transmission data is divided by the demultiplexer 100 to generate n data streams. Each data stream is S / P converted by the S / P converters 110-1 to 110-n, and parallel data is generated for each data stream. The parallel data is input to the IFFT units 130-1 to 130-n via the data exchange unit 120, subjected to IFFT processing by the IFFT units 130-1 to 130-n, and the parallel data of each data stream is transmitted to subcarriers whose frequencies are orthogonal to each other. Be placed. That is, when the operation starts, IFFT processing is performed without exchanging data between the data streams.

  Each data stream after IFFT processing is input to P / S converters 140-1 to 140-n and P / S converted to generate an OFDM symbol.

  In the OFDM symbols of each data stream, guard intervals are inserted by GI insertion sections 150-1 to 150-n, and power is measured by power measurement sections 160-1 to 160-n (ST1000). The measured power is compared with a predetermined threshold (ST1100), and if the result of this comparison is that the measured power is less than or equal to the predetermined threshold for all data streams, this OFDM symbol is transmitted to radio transmitters 170-1 to n. Thus, D / A conversion and up-conversion processing such as up-conversion are performed and transmitted via the transmission antennas 180-1 to 180-n (ST1200).

  On the other hand, if there is a data stream whose measured power exceeds a predetermined threshold as a result of the power comparison, the measured power of each data stream is notified to the exchange pattern determination unit 190. Then, the exchange pattern determining unit 190 exchanges a part of the parallel data of the data stream whose measured power is equal to or greater than a predetermined threshold with a part of the parallel data of another data stream in units of subcarriers. A pattern is determined and output to the data exchange unit 120 as control information. Then, the data exchange unit 120 exchanges parallel data based on the control information (ST1300). Since the multicarrier communication apparatus according to the present embodiment performs MIMO transmission, the data content of each data stream is different, and the parallel data of each data stream is exchanged by exchanging a part of the parallel data in this way. The phase of the arranged subcarrier changes, that is, the power changes, and the transmission peak power can be suppressed.

  When parallel data is exchanged, IFFT processing is again performed by IFFT units 130-1 to 130-n, and P / S conversion is performed by P / S conversion units 140-1 to 140-n to generate OFDM symbols. Further, a guard interval is inserted into the OFDM symbol by the GI insertion units 150-1 to 150-n, and the power of the OFDM symbol is measured by the power measurement units 160-1 to 160-n and compared with a predetermined threshold value. Thereafter, similar to the above operation, parallel data exchange is performed until the power of all OFDM symbols is equal to or lower than a predetermined threshold, and the power of all OFDM symbols is equal to or lower than the predetermined threshold (that is, the transmission peak). When the power is suppressed), the OFDM symbols are transmitted by the radio transmission units 170-1 to 170-n via the transmission antennas 180-1 to 180-n.

  Next, a specific example of the replacement pattern will be described with reference to FIGS. Here, in order to simplify the description, the multicarrier communication apparatus has two transmission antennas A and B. However, even when the number of transmission antennas is three or more, the multicarrier communication apparatus is arranged in parallel by an exchange pattern based on the same concept. You only need to exchange data.

  FIG. 4 is a diagram schematically showing data streams transmitted from the transmission antennas A and B, respectively. In the figure, the horizontal axis indicates frequency and the vertical axis indicates time.

From transmission antenna A, four symbols are transmitted by five subcarriers belonging to group 300 and five subcarriers belonging to group 310, respectively. Similarly, 4 symbols are transmitted from transmission antenna B by 5 subcarriers belonging to group 320 and 5 subcarriers belonging to group 330, respectively. Note that the subcarriers belonging to group 300 and the subcarriers belonging to group 320 have the same frequency, and the subcarriers belonging to group 310 and the subcarriers belonging to group 330 have the same frequency. P _A and P _B indicate orthogonal pilot symbols that are periodically inserted.

  In the present embodiment, it is assumed that a pattern for exchanging data between groups of subcarriers having the same frequency is used as the exchange pattern. Therefore, when there is a data stream whose measured power is equal to or greater than a predetermined threshold in the power measuring units 160-1 to 160-n, for example, as shown in FIG. 5, the pattern for exchanging the symbols of the group 310 and the symbols of the group 330 is exchanged It is determined by the pattern determining unit 190, and this exchange pattern is notified to the data exchanging unit 120 as control information, and data is actually exchanged.

  At this time, since orthogonal pilot symbols are also exchanged as shown in FIG. 5, normal propagation path estimation is performed by the propagation path estimation unit 290 of the multicarrier communication apparatus on the receiving side, and data separation is performed based on the result. Is performed by the data separation unit 250, the receiving-side multicarrier communication apparatus can correctly separate and demodulate data without side information regarding the data exchange pattern.

  As described above, according to the present embodiment, a part of data of a data stream whose measured power is equal to or greater than a predetermined threshold is used as a part of data of another data stream arranged on a subcarrier having the same frequency as this data. Therefore, it is possible to suppress the transmission peak power without using side information and without reducing the transmission efficiency without performing non-linear processing.

(Embodiment 2)
The feature of Embodiment 2 of the present invention is that the number of exchange patterns is increased by introducing side information to enhance the transmission peak power suppression effect.

  Since the configuration of the transmission-side multicarrier communication apparatus according to Embodiment 2 is the same as that of the transmission-side multicarrier communication apparatus according to Embodiment 1 (FIG. 1), description thereof is omitted.

  FIG. 6 is a block diagram showing a configuration of a receiving-side multicarrier communication apparatus according to Embodiment 2. In FIG. In the multicarrier communication apparatus shown in the figure, the same parts as those in the multicarrier communication apparatus shown in FIG. 6 includes receiving antennas 200-1 to 200-n, radio receiving units 210-1 to 210-n, GI removing units 220-1 to n, S / P converters 230-1 to 230-n, and FFT unit 240. −1 to n, data separation unit 250, data exchange unit 255, demodulation units 260-1 to n, P / S conversion units 270-1 to n, multiplexer 280, propagation path estimation unit 290, and exchange pattern information extraction unit 295 have.

  Data exchange section 255 exchanges data arranged on subcarriers in each group between data streams based on exchange pattern information transmitted as side information from the transmission-side multicarrier communication apparatus.

  Exchange pattern information extraction section 295 extracts an exchange pattern transmitted as side information from the transmission-side multicarrier communication apparatus from the data stream.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described.

  First, as in the first embodiment, transmission data is divided by the demultiplexer 100, and n data streams are generated. Each data stream is S / P converted by the S / P converters 110-1 to 110-n, and parallel data is generated for each data stream. The parallel data is input to the IFFT units 130-1 to 130-n via the data exchange unit 120, subjected to IFFT processing by the IFFT units 130-1 to 130-n, and the parallel data of each data stream is transmitted to subcarriers whose frequencies are orthogonal to each other. Be placed. At this time, in the present embodiment, a dedicated subcarrier for arranging the exchange pattern information for notifying the receiving side multicarrier communication apparatus of the exchange pattern is prepared.

  Each data stream after IFFT processing is input to P / S converters 140-1 to 140-n and P / S converted to generate an OFDM symbol.

  In the OFDM symbols of each data stream, guard intervals are inserted by the GI insertion units 150-1 to 150-n, and power is measured by the power measurement units 160-1 to 160-n. The measured power is compared with a predetermined threshold value, and if the result of this comparison is that the measured power is less than or equal to the predetermined threshold value for all data streams, this OFDM symbol is transmitted by the radio transmitters 170-1 to 170-n. Radio transmission processing such as A conversion and up-conversion is performed and transmitted via the transmission antennas 180-1 to 180-n.

  On the other hand, if there is a data stream whose measured power is equal to or greater than a predetermined threshold as a result of the power comparison, the measured power of each data stream is notified to the exchange pattern determining unit 190. Then, the exchange pattern determining unit 190 exchanges a part of the parallel data of the data stream whose measured power is equal to or greater than a predetermined threshold with a part of the parallel data of another data stream in units of subcarriers. A pattern is determined and output to the data exchange unit 120 as control information. Then, the data exchange unit 120 exchanges parallel data based on the control information.

  At this time, exchange pattern information for notifying the receiving side multicarrier communication apparatus of the exchange pattern determined by the exchange pattern determining unit 190 is arranged on a dedicated subcarrier. This exchange pattern information may be transmitted from a plurality of transmission antennas via MIMO, or may be transmitted from only one transmission antenna that is predicted to correspond to the best propagation path characteristics. .

  Thereafter, as in the first embodiment, data exchange is performed until the power of all OFDM symbols is equal to or lower than a predetermined threshold, and the power of all OFDM symbols is equal to or lower than the predetermined threshold (that is, the transmission peak). When the power is suppressed), the OFDM symbols are transmitted by the radio transmission units 170-1 to 170-n via the transmission antennas 180-1 to 180-n.

  Each transmitted OFDM symbol is multiplexed on the propagation path, received by each receiving antenna 200-1 to 200-n, and subjected to radio reception processing such as down-conversion and A / D conversion by the radio receiving units 210-1 to 210-n. The The OFDM symbol after the radio reception process is subjected to S / P conversion by S / P conversion units 230-1 to 230-n after the guard interval is removed by GI removal units 220-1 to 220-n, and FFT is performed by FFT units 240-1 to n. It is processed. Then, by using the FFT processing result, the propagation path estimation unit 290 performs propagation path estimation, and the data separation unit 250 separates the data of each subcarrier so as to correspond to the data stream after group exchange on the transmission side. Is done.

  The exchange pattern information extraction unit 295 extracts exchange pattern information from each data stream obtained by the separation. As described above, this exchange pattern information may be included in a plurality of data streams, or may be included in only one data stream.

  Then, based on the extracted exchange pattern information, the data exchange unit 255 exchanges data so as to correspond to the data stream before the group exchange in the transmission-side multicarrier communication apparatus. As a result, the data order is the same as that before the group exchange in the multicarrier communication apparatus on the transmission side. Each data stream after the exchange of data is demodulated by demodulating sections 260-1 to 260-n, P / S converted by P / S converting sections 270-1 to 270-1 and multiplexed by multiplexer 280, and received data is obtained.

  Next, a specific example of the exchange pattern will be described with reference to FIGS. 4 and 7. Here, in order to simplify the explanation, the multicarrier communication apparatus has two transmission antennas A and B. However, even when the number of transmission antennas is three or more, data is exchanged based on an exchange pattern based on the same concept. You can replace it.

  In the present embodiment, a part of data in the data stream shown in FIG. 4 can be exchanged to generate a data stream as shown in FIG. That is, an exchange pattern for exchanging data between groups of subcarriers having different frequencies can be used. Therefore, when there is a data stream in which the measured power is greater than or equal to a predetermined threshold in the power measuring units 160-1 to 160-n, for example, as shown in FIG. The exchange pattern is determined as control information to the data exchange unit 120, and data exchange is actually performed.

  At this time, as shown in FIG. 7, orthogonal pilot symbols are not exchanged and are fixedly assigned to each transmission antenna, so that data exchange is possible between groups of subcarriers of different frequencies. In addition, exchange pattern information belonging to group 400 and group 410 is arranged on a dedicated subcarrier and transmitted.

  Since the exchange pattern information in the present embodiment is label information corresponding to the exchange pattern, the information on the side information is compared with the PTS that transmits the phase coefficient series described in the conventional technique as side information. The amount is small and the degree to which the transmission efficiency decreases is small.

  Further, since the orthogonal pilot symbols are excluded from the exchange targets, the reception-side propagation path estimation unit 290 can perform interpolation processing on the propagation path estimation values between groups.

  As described above, according to the present embodiment, since a part of data of a data stream whose measured power is equal to or greater than a predetermined threshold is exchanged with a part of data other than pilot symbols of another data stream, nonlinear processing is performed. Without performing transmission, it is possible to prevent an increase in interference, exchange data more freely, and further suppress transmission peak power.

(Embodiment 3)
A feature of Embodiment 3 of the present invention is that spatial correlation between a transmission antenna and a reception antenna is removed by performing directional transmission using different transmission weights for each data stream.

  FIG. 8 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 3. In FIG. In the multicarrier communication apparatus shown in the figure, the same parts as those in the multicarrier communication apparatus shown in FIG. The multicarrier communication apparatus shown in FIG. 8 includes a demultiplexer 100, S / P conversion units 110-1 to 110-n, a data exchange unit 120, IFFT units 130-1 to 130-n, P / S conversion units 140-1 to 140-n, GI. Insertion unit 150-1 to n, power measurement unit 160-1 to n, radio transmission unit 170-1 to n, transmission antenna 180-1 to n, exchange pattern determination unit 190, and directivity weight forming unit 500 ing.

  The directivity weight forming unit 500 weights each data stream using different directivity weights.

  The configuration of the receiving-side multicarrier communication apparatus according to Embodiment 3 is the same as that of the receiving-side multicarrier communication apparatus according to Embodiment 1 (FIG. 2), and thus description thereof is omitted.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described. The operation of the reception-side multicarrier communication apparatus (FIG. 2) in the present embodiment is the same as the operation of the conventional multicarrier communication apparatus, and thus the description thereof is omitted.

  First, as in the first embodiment, transmission data is divided by the demultiplexer 100, and n data streams are generated. Each data stream is S / P converted by the S / P converters 110-1 to 110-n, and parallel data is generated for each data stream. The parallel data is input to the IFFT units 130-1 to 130-n via the data exchange unit 120, subjected to IFFT processing by the IFFT units 130-1 to 130-n, and the parallel data of each data stream is transmitted to subcarriers whose frequencies are orthogonal to each other. Be placed.

  Then, each data stream after IFFT processing is input to directivity weight forming section 500, and weighted using a different directivity weight for each data stream. Each weighted data stream is input to P / S converters 140-1 to 140-n and P / S converted to generate an OFDM symbol.

  In the OFDM symbols of each data stream, guard intervals are inserted by the GI insertion units 150-1 to 150-n, and power is measured by the power measurement units 160-1 to 160-n. The measured power is compared with a predetermined threshold value, and if the result of this comparison is that the measured power is less than or equal to the predetermined threshold value for all data streams, this OFDM symbol is transmitted by the radio transmitters 170-1 to 170-n. Radio transmission processing such as A conversion and up-conversion is performed, and directional transmission is performed via the transmission antennas 180-1 to 180-n.

  At this time, since each data stream is weighted by the directivity weight, for example, when there are four transmission antennas (when n = 4), the four data streams 1 to 4 have different directivities as shown in FIG. Sent by sex. In other words, the correspondence relationship between the directivity and the data stream is changed by the exchange of data by the data exchange unit 120 instead of the one-to-one correspondence between the transmission antenna and the data stream. Thereby, the spatial correlation between the transmission antenna and the reception antenna of each data stream is removed, and the accuracy of data separation in the multicarrier communication apparatus on the reception side can be improved.

  On the other hand, if there is a data stream whose measured power is equal to or greater than a predetermined threshold as a result of the power comparison, the measured power of each data stream is notified to the exchange pattern determining unit 190. Then, the exchange pattern determining unit 190 exchanges a part of the parallel data of the data stream whose measured power is equal to or greater than a predetermined threshold with a part of the parallel data of another data stream in units of subcarriers. A pattern is determined and output to the data exchange unit 120 as control information. Then, the data exchange unit 120 exchanges parallel data based on the control information.

  Thereafter, as in the first embodiment, data exchange is performed until the power of all OFDM symbols is equal to or lower than a predetermined threshold, and the power of all OFDM symbols is equal to or lower than the predetermined threshold (that is, the transmission peak). When the power is suppressed), each of the OFDM symbols is directionally transmitted via the transmission antennas 180-1 to 180-n by the wireless transmission units 170-1 to 170-n.

  As described above, according to the present embodiment, a part of data of a data stream whose measured power is equal to or greater than a predetermined threshold is used as a part of data of another data stream arranged on a subcarrier having the same frequency as this data. Therefore, the transmission peak power can be suppressed without performing side-by-side information and without reducing transmission efficiency without performing non-linear processing. Further, since weighting is performed using different directivity weights for each data stream, the correlation of the propagation environment can be removed, and the accuracy of data separation on the receiving side can be improved.

  In the present embodiment, not only the correspondence between the data stream and the directivity weight is changed, but also the directivity weight itself used for each data stream may be changed.

(Embodiment 4)
A feature of the fourth embodiment of the present invention is that a plurality of data streams having a coding relationship with each other, generated by space-time coding (STC) or space-frequency coding (SFC). This is a point where multi-carrier modulation is performed.

  FIG. 10 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 4. In FIG. In the multicarrier communication apparatus shown in the figure, the same parts as those in the multicarrier communication apparatus shown in FIG. 10 includes S / P conversion units 110-1 to 110-n, data exchange unit 120, IFFT units 130-1 to n, P / S conversion units 140-1 to 140-n, and GI insertion unit 150-. 1 to n, power measuring units 160-1 to 160-n, wireless transmitting units 170-1 to 170-n, transmitting antennas 180-1 to 180-n, an exchange pattern determining unit 190, and a space-time encoder 600.

  The space-time encoder 600 space-time encodes transmission data and generates a data stream that is in an encoding relationship with each other (ie, information bits and redundant bits for the information bits, for example).

  FIG. 11 is a block diagram showing a configuration of a receiving-side multicarrier communication apparatus according to Embodiment 4. In FIG. In the multicarrier communication apparatus shown in the figure, the same parts as those in the multicarrier communication apparatus shown in FIG. 11 includes receiving antennas 200-1 to 200-n, radio receiving units 210-1 to 210-n, GI removing units 220-1 to 220-n, S / P converters 230-1 to 230-n, and FFT unit 240. −1 to n, a propagation path estimation unit 290, a space-time decoder 700, and a P / S conversion unit 710.

  The space-time decoder 700 performs space-time decoding of each data stream based on the propagation path estimation result output from the propagation path estimation unit 290, and outputs the decoding result.

  P / S converter 710 P / S converts the decoding result to obtain received data.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described.

  First, the transmission data is space-time encoded by the space-time encoder 600 to generate n data streams that are in an encoding relationship with each other. Each data stream is S / P converted by the S / P converters 110-1 to 110-n, and parallel data is generated for each data stream. The parallel data is input to the IFFT units 130-1 to 130-n via the data exchange unit 120, subjected to IFFT processing by the IFFT units 130-1 to 130-n, and the parallel data of each data stream is transmitted to subcarriers whose frequencies are orthogonal to each other. Be placed.

  Each data stream after IFFT processing is input to P / S converters 140-1 to 140-n and P / S converted to generate an OFDM symbol.

  In the OFDM symbols of each data stream, guard intervals are inserted by the GI insertion units 150-1 to 150-n, and power is measured by the power measurement units 160-1 to 160-n. The measured power is compared with a predetermined threshold value, and if the result of this comparison is that the measured power is less than or equal to the predetermined threshold value for all data streams, this OFDM symbol is transmitted by the radio transmitters 170-1 to 170-n. Radio transmission processing such as A conversion and up-conversion is performed and transmitted via the transmission antennas 180-1 to 180-n.

  On the other hand, if there is a data stream whose measured power is equal to or greater than a predetermined threshold as a result of the power comparison, the measured power of each data stream is notified to the exchange pattern determining unit 190. Then, the exchange pattern determining unit 190 exchanges a part of the parallel data of the data stream whose measured power is equal to or greater than a predetermined threshold with a part of the parallel data of another data stream in units of subcarriers. A pattern is determined and output to the data exchange unit 120 as control information. Then, the data exchange unit 120 exchanges parallel data based on the control information.

  At this time, in the STC or SFC, since the data streams are separated on the assumption that the data streams are in an encoding relationship with each other, the data exchange is the same as shown in FIG. 5 (Embodiment 1). This is done only between groups of frequency subcarriers. That is, data exchange is performed so that symbols transmitted at the same time and the same frequency are always in a coding relationship with each other.

  In particular, when block coding such as STTD (Space-Time coded Transmit Diversity) is used as a coding method in the space-time encoder 600, the space-time decoder 700 uses symbols of continuous symbols in terms of time or frequency. The block decoding process is performed on the assumption that the propagation path characteristics hardly fluctuate. For this reason, if the block coding unit in the space-time encoder 600 spans between groups for data exchange in the data exchange unit 120, the above assumption regarding the propagation path characteristics does not hold due to data exchange, and block decoding processing is performed. Cannot be performed correctly. Therefore, a group for data exchange is formed with a block coding unit as a minimum unit.

  Thereafter, as in the first embodiment, data exchange is performed until the power of all OFDM symbols is equal to or lower than a predetermined threshold, and the power of all OFDM symbols is equal to or lower than the predetermined threshold (that is, the transmission peak). When the power is suppressed), the OFDM symbols are transmitted by the radio transmission units 170-1 to 170-n via the transmission antennas 180-1 to 180-n.

  Each transmitted OFDM symbol is multiplexed on the propagation path, received by each receiving antenna 200-1 to 200-n, and subjected to radio reception processing such as down-conversion and A / D conversion by the radio receiving units 210-1 to 210-n. The The OFDM symbol after the radio reception process is subjected to S / P conversion by S / P conversion units 230-1 to 230-n after the guard interval is removed by GI removal units 220-1 to 220-n, and FFT is performed by FFT units 240-1 to n. It is processed. Then, by using the FFT processing result, the channel estimation unit 290 performs channel estimation, and the space-time decoder 700 performs decoding processing corresponding to space-time coding on the transmission side.

  Then, the decoding result is P / S converted by the P / S conversion unit 710 to obtain received data.

  As described above, according to the present embodiment, a part of data of a data stream whose measured power is equal to or greater than a predetermined threshold is used as a part of data of another data stream arranged on a subcarrier having the same frequency as this data. Since this is exchanged with other parts, even in multi-antenna transmissions such as STC and SFC, non-linear processing is not performed to prevent an increase in interference, and side information is not required and transmission peak power is suppressed without reducing transmission efficiency. can do.

  In addition, when a function of performing diffusion in the frequency axis direction is added to the above-described embodiments, the same effect can be obtained by using an exchange pattern that does not break the orthogonality between the diffusion chips.

1 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing a configuration of a receiving-side multicarrier communication apparatus according to Embodiment 1; FIG. 3 is a flowchart showing the operation of the transmission-side multicarrier communication apparatus according to the first embodiment. The figure which shows an example of the data stream transmitted from several transmission antennas The figure which shows an example of the exchange of the data in the multicarrier communication apparatus of the transmission side which concerns on Embodiment 1 FIG. 5 is a block diagram showing a configuration of a receiving-side multicarrier communication apparatus according to Embodiment 2 of the present invention. The figure which shows an example of the exchange of the data in the multicarrier communication apparatus of the transmission side which concerns on Embodiment 2. FIG. 9 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 3 of the present invention. The figure for demonstrating operation | movement of the multicarrier communication apparatus of the transmission side which concerns on Embodiment 3. FIG. FIG. 9 is a block diagram showing a configuration of a transmission-side multicarrier communication apparatus according to Embodiment 4 of the present invention. FIG. 9 is a block diagram showing a configuration of a receiving-side multicarrier communication apparatus according to Embodiment 4;

Explanation of symbols

100 Demultiplexer 110-1 to n, 230-1 to n S / P converter 120, 255 Data exchange unit 130-1 to n IFFT unit 140-1 to n, 270-1 to n, 710 P / S converter 150-1 to n GI insertion unit 160-1 to n power measurement unit 170-1 to n radio transmission unit 180-1 to n transmission antenna 190 exchange pattern determination unit 200-1 to n reception antenna 210-1 to n radio reception Unit 220-1 to n GI removal unit 240-1 to n FFT unit 250 data separation unit 260-1 to n demodulation unit 280 multiplexer 290 propagation path estimation unit 295 exchange pattern information extraction unit 500 directivity weight formation unit 600 space-time encoder 700 space-time decoder

Claims (17)

A multi-carrier communication apparatus for simultaneously transmitting a plurality of different data streams from a plurality of antennas using the same carrier group,
Determining means for determining whether peak power occurs in at least one data stream;
An exchanging means for exchanging a part of data of the data stream with a part of data of another data stream when it is determined that peak power is generated;
A multi-carrier communication apparatus comprising: The determination means includes
A measurement unit for measuring the power of each data stream;
A comparator that compares the measured power with a predetermined threshold;
The multicarrier communication apparatus according to claim 1, wherein, as a result of the comparison, it is determined that peak power is generated in a data stream whose measured power is equal to or greater than a predetermined threshold. The exchange means is
An exchange pattern determining unit for determining a pattern for exchanging a part of data of each data stream in units of a predetermined carrier group;
A data exchange unit for exchanging a part of data of each data stream according to the decided exchange pattern;
The multicarrier communication apparatus according to claim 1, further comprising: The exchange pattern determination unit
4. The multicarrier communication apparatus according to claim 3, wherein a pattern for exchanging data between groups having the same frequency among the groups of carriers is determined. The exchange pattern determination unit
4. The multicarrier communication apparatus according to claim 3, wherein a pattern for exchanging data between groups having different frequencies among the groups of carriers is determined. The data exchange unit
4. The multicarrier communication apparatus according to claim 3, wherein orthogonal pilot data included in a part of data of each data stream is exchanged. The data exchange unit
4. The multicarrier communication apparatus according to claim 3, wherein orthogonal pilot data included in a part of data of each data stream is not exchanged. The exchange means is
The multicarrier communication apparatus according to claim 1, further comprising transmission means for transmitting exchange pattern information for notifying a communication partner station of a pattern for exchanging data. The transmission means includes
9. The multicarrier communication apparatus according to claim 8, wherein the exchange pattern information is transmitted using a specific carrier excluded from exchange targets. Forming means for forming different directivity weights for each data stream;
The forming means includes
The multicarrier communication apparatus according to claim 1, wherein when data is exchanged by said exchange means, directional weights are exchanged correspondingly.   The multicarrier communication apparatus according to claim 1, further comprising generating means for encoding transmission data and generating a plurality of different data streams that are encoded with each other. The generating means includes
Block encoding transmission data for each predetermined block encoding unit;
The exchange means is
12. The multicarrier communication apparatus according to claim 11, wherein data exchange is performed using the block coding unit as a minimum unit.   12. The multicarrier communication apparatus according to claim 11, wherein the generation means generates a plurality of different data streams by convolutionally encoding transmission data.   12. The multicarrier communication apparatus according to claim 11, wherein the generation unit generates a plurality of different data streams by turbo-coding transmission data.   A communication terminal apparatus comprising the multicarrier communication apparatus according to claim 1.   A base station apparatus comprising the multicarrier communication apparatus according to claim 1. A multi-carrier communication method for simultaneously transmitting a plurality of different data streams from a plurality of antennas using the same carrier group,
Determining whether peak power occurs in at least one data stream;
Exchanging some data of the data stream with some data of another data stream when it is determined that peak power is generated;
A multi-carrier communication method comprising:

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