JP2006325264A - Base station apparatus and wireless communication method - Google Patents

Abstract

[PROBLEMS] To reduce the interference of other cells by hopping and to use a frequency in a good propagation state, and to transmit at high speed.
A scheduler unit 102 performs scheduling to determine which user is to be transmitted using CQI (from each communication terminal apparatus, selects a user signal to be transmitted in the next frame, and in which subcarrier block The MCS determination unit 103 selects a modulation scheme and an encoding method from the CQI of the selected user signal, and the subcarrier block selection unit 110 selects a subcarrier block indicated by the scheduler unit 102 for each user signal. The hopping patterns are selected by the FH sequence selection units 111-1 to 111-n for each subcarrier block, and the subcarrier mapping unit 112 sub-processes user signals and control data according to the selected hopping patterns. Map to carrier.
[Selection] Figure 1

Description

  The present invention relates to a base station apparatus and a radio communication method, and more particularly to a base station apparatus and a radio communication method suitable for use in an OFDM system.

  OFDM (Orthogonal Frequency Division Multiplexing) has attracted attention as a high-speed transmission technology that is resistant to multipath interference. FH-OFDM (Frequency hopping-OFDM) is a method of hopping an OFDM subcarrier to be used every moment, and is used in IEEE 802.16 or the like as an access method with which a frequency diversity effect can be obtained (Non-patent Document 1). ).

  In addition, FH-OFDM has an effect of averaging interference from other cells in a cellular environment, and is attracting attention as a future high-speed wireless transmission technology (Non-patent Document 2). In addition, introduction of FH-OFDM is also being studied in 3GPP (Non-patent Document 3).

  In FH-OFDM, each base station apparatus transmits according to each FH pattern. The FH pattern is a pattern related to the transition of time and the used frequency (subcarrier), and each base station apparatus is assigned a unique FH pattern. The frequency of FH (frequency hopping) can be considered for each symbol and for each slot (or frame). Here, FH for each symbol is considered. The effect of FH is that a frequency is used over a wide range, so that a frequency diversity effect can be obtained and a temporal averaging effect can be obtained for interference with other cells.

  As a method for realizing FH, a method using frequency interleaving as described in Non-Patent Document 3 and a case of using a pattern generated by a random sequence such as a PN sequence are considered. Here, the latter is considered for simplicity.

  In Non-Patent Document 4, it is proposed to divide a band into subchannels and perform DCA (Dynamic Channel Allocation) in that unit. In Non-Patent Document 4, however, the channel is divided for each cell. However, it is not divided so that the optimum frequency can be used as in the present invention.

  Hereinafter, conventional base station apparatuses and mobile station apparatuses will be described. FIG. 12 is a block diagram showing a configuration of a conventional base station apparatus.

  In FIG. 12, the scheduler unit 11 performs scheduling for determining which user is to be transmitted using CQI (Channel Quality Information) from each mobile station apparatus. There are algorithms such as MaxC / I and Round Robin. Also, an encoding method (coding rate) and a modulation method to be used are determined from the CQI. The encoding unit 12 performs encoding such as turbo encoding on user data. The encoding unit 12 also performs processing such as interleaving as necessary.

  The transmission HARQ unit 13 performs processing necessary for HARQ. Details will be described with reference to FIG. FIG. 13 is a block diagram showing a configuration of a transmission HARQ unit of a conventional base station apparatus. As shown in FIG. 13, the transmission HARQ unit 13 includes a buffer 21 and a rate matching unit 22. The buffer 21 stores a bit string of transmission data. The rate matching unit 22 performs rate matching determined by the RM parameter on the bit string of the transmission data, and inputs the punctured or repeated transmission data to the modulation unit 14. The RM parameter may differ depending on the number of transmissions.

  The modulation unit 14 modulates transmission data with QPSK or QAM. The control data processing unit 15 includes an encoding unit 16 and a modulation unit 17. The encoding unit 16 encodes the control data. The modulation unit 17 modulates the control data. The multiplexing unit 18 multiplexes (in this case, time multiplexing) the transmission data processed by the modulation unit 14 with a control signal that has been similarly encoded and modulated.

  Next, the subcarrier mapping unit 19 assigns transmission data and control signals to subcarriers according to a predetermined FH pattern. Similarly, the subcarrier mapping unit 19 performs mapping so that the pilot signal is also distributed over the entire frequency band. Then, the subcarrier mapping unit 19 outputs a transmission signal obtained by mapping the transmission data, the control signal, and the pilot signal to the S / P conversion unit 20.

  The S / P converter 20 converts the transmission signal from serial data to parallel data and outputs the converted signal to the IFFT unit 21.

  The IFFT unit 21 performs IFFT (Inverse Fast Fourier Transform) on the transmission signal converted into parallel data. The GI insertion unit 22 inserts a GI (Guard Interval) for enhancing multipath tolerance into the transmission signal. The wireless processing unit 23 transmits the transmission signal after the wireless transmission process.

  At this time, the state of the subcarriers used is, for example, as shown in FIG. FIG. 14 is a diagram illustrating an example of a signal of a conventional base station apparatus. In FIG. 14, the vertical axis represents time, and the horizontal axis represents the subcarrier frequency. As shown in FIG. 14, the subcarriers in which the pilot signal and the data signal are arranged differ from time to time.

  In this way, the mobile station apparatus receives a signal in which subcarriers for arranging transmission signals are changed every time. FIG. 15 is a block diagram showing a configuration of a conventional mobile station apparatus.

  In FIG. 15, the radio processing unit 51 first performs radio reception processing such as down-conversion on the received signal to obtain a baseband signal. The GI removal unit 52 removes the inserted GI. The FFT unit 53 extracts a signal on each subcarrier by performing FFT processing. The subcarrier demapping unit 54 demaps this received signal according to the FH pattern, and extracts a signal addressed to itself.

  Next, the channel separation unit 55 separates the received signal into a user signal, a control signal, and a pilot. The demodulator 56 demodulates the control signal, and the decoder 57 performs a decoding process on the control signal after the demodulation process.

  The demodulator 58 demodulates the user signal. The reception HARQ unit 59 stores a predetermined amount of bits (here, soft decision bits) in the reception HARQ unit after demodulation processing. In the case of retransmission, it is combined with the previous received bit stored. The decoding unit 60 performs decoding such as a turbo code using the bit string to obtain user data. Here, although not shown, a channel estimation value calculated using a pilot signal is used during demodulation processing. The ACK / NACK generation unit 61 determines whether an error is included from the CRC result of the decoded received data, and transmits the ACK signal or the NACK signal on the uplink.

Further, CIR measurement unit 62 calculates an average received SIR of all subcarriers using the pilot signal. The CQI generator 63 generates a CQI from the average received SIR. Transmitter 64 transmits CQI and ACK / NACK signals on the uplink.
“IEEE Standard 802.16: A technical overview of the Wireless MAN Air Interface for broadband wireless access”, pp. 98-107, IEEE Communication Magazine, June, 2002 http://www.flarion.com/technology/tech_intro.html 3GPP TSG RAN WG1 meeting # 28bis, R1-02-1222 "Dynamic channel allocation schemes in mobile radio systems with frequency hopping", Verdone, R .; Zanella, A .; Zuliani, L., pp. E-157-E-162, vol.2, Personal, Indoor and Mobile Radio Communications, 2001 12th IEEE International Symposium on, Sep / Oct 2001

  However, in the conventional apparatus, the frequency diversity effect can be obtained by widening the use band by frequency hopping, but there is a problem that the effect of frequency scheduling for transmission using a frequency with a good channel condition cannot be obtained. In addition, since the frequency hopping range is wide in the conventional apparatus, the amount of control information when assigning a hopping pattern to each user as a channel resource becomes enormous.

  In addition, in the conventional apparatus, in frequency scheduling for transmitting a packet using a frequency with good reception quality, if the same frequency is assigned to another mobile station apparatus even in a base station apparatus of an adjacent cell, the packet is received due to interference. There is a problem that makes it impossible.

  The present invention has been made in view of the above points, and can reduce the interference of other cells by hopping, can use a frequency in a good propagation state, can perform high-speed transmission, and has a control information amount for resource allocation. Another object of the present invention is to provide a base station apparatus and a wireless communication method that can reduce the amount of data.

  The base station apparatus of the present invention is a base station apparatus that performs wireless communication using a multicarrier communication band divided into a plurality of blocks, and the first transmission data includes the plurality of blocks based on the communication quality for each block. Allocating means for allocating any of the plurality of blocks according to a predetermined pattern to the second transmission data different from the first transmission data while allocating any one of the blocks according to a predetermined pattern, And a hopping means for frequency hopping the allocated first transmission data and second transmission data within each block.

  According to the present invention, the frequency-hopped received signal is restored to the original signal in units of subcarrier blocks, so that it is possible to use a frequency with good propagation conditions while reducing other cell interference by hopping. Can be transmitted.

  The present inventor has paid attention to the fact that in the FH-OFDM system, the frequency diversity effect can be obtained by expanding the use band by hopping, but the effect of frequency scheduling for transmission using a frequency with a good propagation path condition cannot be obtained.

  In the frequency scheduling, the mobile station apparatus measures the reception quality of each frequency (subcarrier) and reports it to the base station apparatus. The base station device transmits a packet to the mobile station device using a frequency with good reception quality.

  Furthermore, if the inventor assigns the same frequency to another mobile station apparatus even in a base station apparatus in an adjacent cell, the packet cannot be received due to interference. Accordingly, the present invention has been focused on the fact that it is necessary to reduce interference from other cells even when performing frequency scheduling.

  That is, the gist of the present invention is that the band is divided into subcarrier blocks, the base station apparatus selects a subcarrier block to be used in the frame by frequency scheduling, and each user signal is frequency hopped within the block. It is possible to use higher frequency transmission because it is possible to use a frequency in a good propagation state while reducing interference from other cells by hopping.

  The present invention is a method of obtaining a frequency scheduling effect at the expense of the frequency diversity effect by narrowing the hopping range, and is particularly effective in an environment with a large number of users and a large delay dispersion. Further, even in other environments, the number of frequency hopping patterns can be reduced by dividing the band into subcarrier blocks, which is effective and effective in reducing the amount of control information for resource allocation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In the present embodiment, in transmission using FH-OFDM, the use frequency band is divided into subcarrier blocks, and the base station apparatus selects a subcarrier block to be used in the frame for each user by frequency scheduling. explain. Each user signal is frequency hopped within the block. By dividing the used frequency band into subcarrier blocks, it is possible to assign a user with an optimum frequency. In addition, other cell interference is reduced by hopping used subcarriers within the block.

  FIG. 1 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention. 1 includes a reception unit 101, a scheduler unit 102, an MCS determination unit 103, an encoding unit 104-1, an encoding unit 104-2, a transmission HARQ unit 105-1, and a transmission. HARQ section 105-2, modulation section 106-1, modulation section 106-2, control data processing section 107, encoding section 108, modulation section 109, subcarrier block selection section 110, and FH sequence It mainly comprises a selection unit 111-1 to 111-n, a subcarrier mapping unit 112, an S / P conversion unit 113, an IFFT unit 114, a GI insertion unit 115, and a radio processing unit 116.

  In FIG. 1, a receiving unit 101 receives a received signal transmitted from a communication terminal device which is a communication partner, converts the frequency of the received signal into a baseband signal, decodes it, and extracts CQI information. Then, receiving section 101 outputs CQI information to scheduler section 102 and MCS determining section 103.

  The scheduler unit 102 performs scheduling for determining which user is to be transmitted using CQI (Channel Quality Information) from each communication terminal apparatus, and selects a user signal to be transmitted in the next frame. There are algorithms such as MaxC / I and Round Robin. At this time, scheduler section 102 determines which subcarrier block to transmit at the same time, and outputs it to subcarrier block selection section 110. Here, scheduler section 102 selects the subcarrier block of the best propagation path.

  The MCS determination unit 103 selects a modulation method and a coding method (coding rate) from the CQI of the selected user signal, outputs the coding method to the coding unit 104-1 and the coding unit 104-2, and performs modulation. The system is output to modulation sections 106-1 and 106-2.

  The encoding unit 104-1 and the encoding unit 104-2 perform encoding such as turbo encoding on user data using an encoding method instructed by the MCS determination unit 103. In addition, the encoding unit 104-1 and the encoding unit 104-2 also perform processing such as interleaving as necessary. Then, encoding section 104-1 and encoding section 104-2 output the encoded user data to transmission HARQ section 105-1 and transmission HARQ section 105-2.

  The transmission HARQ unit 105-1 and the transmission HARQ unit 105-2 encode the user signal by the instructed encoding method, and then store the data in the HARQ buffer and rate matching processing according to the number of retransmissions in the transmission HARQ unit I do. Then, the encoded user signal is output to modulation section 106-1 and modulation section 106-2.

  Modulation section 106-1 and modulation section 106-2 modulate the user signal with the modulation scheme instructed by MCS determination section 103 and output the result to subcarrier block selection section 110.

  The control data processing unit 107 includes an encoding unit 108 and a modulation unit 109. The encoding unit 108 encodes the control data and outputs it to the modulation unit 109. Modulation section 109 modulates the control data and outputs it to subcarrier block selection section 110.

  Subcarrier block selection section 110 assigns a subcarrier block instructed to scheduler section 102 to each user signal, and hopping patterns are selected by FH sequence selection sections 111-1 to 111-n for the respective subcarrier blocks.

  For control data such as subcarrier block allocation information and MCS information, predetermined subcarrier blocks and FH sequences are selected. Therefore, subcarrier block selection section 110 selects a user signal that is different from the FH sequence of control data.

  Then, subcarrier mapping section 112 maps the user signal and control data to subcarriers according to the selected hopping pattern. An example of mapping at this time is shown in FIG. FIG. 2 is a diagram illustrating an example of subcarrier mapping of the base station apparatus according to the present embodiment.

  In FIG. 2, the horizontal axis indicates the frequency of the subcarrier, and the vertical axis indicates the time in frame units. As shown in FIG. 2, the signal is frequency hopped in units of subcarrier blocks. Then, a subcarrier block for mapping a signal is determined for each frame. As a subcarrier block for mapping this signal, a subcarrier block having a good propagation path condition is selected for each frame. Although not shown, pilot signals are also mapped simultaneously.

  The S / P converter 113 converts the mapped signal from serial data to parallel data and outputs the converted data to the IFFT unit 114. IFFT section 114 performs IFFT (Inverse Fast Fourier Transform) on the transmission signal converted into parallel data. The GI insertion unit 115 inserts a GI (Guard Interval) for enhancing multipath tolerance into the transmission signal. The radio processing unit 116 converts the transmission signal into a radio frequency and transmits it.

  Thus, according to the base station apparatus of this embodiment, a band is divided into subcarrier blocks, and subcarrier blocks to be used in units of frames are selected by frequency scheduling, and each user signal has a frequency within that block. By hopping, it is possible to use a frequency with a good propagation state while reducing other cell interference by hopping, and to transmit at high speed. Further, by dividing the band into subcarrier blocks, the number of frequency hopping patterns can be reduced, and the amount of control information for resource allocation can be reduced.

  The present invention is a method of obtaining a frequency scheduling effect at the expense of the frequency diversity effect by narrowing the hopping range, and is particularly effective in an environment with a large number of users and a large delay dispersion.

  Next, a communication terminal apparatus that communicates with the base station apparatus 100 will be described. FIG. 3 is a block diagram showing a configuration of the communication terminal apparatus according to the present embodiment. 3 includes a wireless processing unit 201, a GI removal unit 202, an FFT unit 203, a subcarrier block extraction unit 204, data sequence reproduction units 205-1 and 205-2, and a demodulation unit 206. -1 and 206-2, a decoding unit 207, a reception HARQ unit 208, a decoding unit 209, an ACK / NACK generation unit 210, a pilot signal extraction unit 211, a CIR measurement unit 212, and a CQI generation unit 213 The transmission unit 214 is mainly configured.

  In FIG. 3, radio processing section 201 down-converts the received signal into a baseband signal and outputs it to GI removal section 202. The GI removal unit 202 removes the GI from the received signal and outputs the GI to the FFT unit 203. The FFT unit 203 converts the received signal into the frequency domain by fast Fourier transform, and outputs it to the subcarrier block extraction unit 204.

  Subcarrier block extraction section 204 separates the received signal for each subcarrier block, and outputs it to data series reproduction sections 205-1 and 205-2. The data series reproducing units 205-1 and 205-2 perform processing for restoring the hopped data series for each data series to be received. This process is performed using subcarrier block allocation information and FH sequence allocation information included in the control data. Data sequence reproduction section 205-1 then outputs the processed received signal (control data) to demodulation section 206-1. In addition, data sequence reproduction section 205-2 outputs the received signal (user data) after processing to demodulation section 206-2.

  Demodulation section 206-1 demodulates the received signal and outputs it to decoding section 207. Demodulation section 206-2 demodulates the received signal and outputs it to HARQ section 208.

  Decoding section 207 demodulates the received signal to QPSK or 16QAM, outputs subcarrier block allocation information included in the received signal to subcarrier block extraction section 204, and converts FH sequence allocation information to data sequence reproduction section 205-1. And output to the data series reproduction unit 205-2.

  Reception HARQ section 208 combines received data with received data at the time of retransmission using reception HARQ, stores data for new data, and outputs the received signal after processing to decoding section 209. The decoding unit 209 demodulates the QPSK or 16QAM reception signal to obtain user data. Also, the decoding unit 209 outputs CRC (Cycle Redundancy Check) information of the decoded user data to the ACK / NACK generation unit 210.

  The ACK / NACK generation unit 210 generates an ACK signal indicating whether or not user data has been correctly received or a signal indicating a NACK signal, and outputs the signal to the transmission unit 214.

  Here, since the use subcarrier block and the FH sequence are determined in advance for the control data, the control data is decoded first and then the user data is processed. In addition, pilot signal extraction section 211 extracts a pilot signal included in each block extracted by subcarrier block extraction section 204 and outputs the pilot signal to CIR measurement section 212. CIR measuring section 212 measures CIR for each subcarrier block. It is conceivable that the reception power is measured not as CIR but as reception power.

  The CQI generation unit 213 generates a CQI signal from the CIR and outputs it to the transmission unit 214. Transmitter 214 modulates and frequency-converts the ACK signal or NACK signal and CQI signal, and transmits the result as a radio signal.

  Next, the internal configuration of the CIR measurement unit 212 will be described. FIG. 4 is a block diagram showing a configuration of the CIR measurement unit of the communication apparatus according to the present embodiment.

  Signal power calculation sections 301-1 to 301-3 calculate the power value of a desired signal of each subcarrier block and output it to CIR calculation sections 303-1 to 303-3.

  Interference power calculation sections 302-1 to 302-3 calculate the power value of the interference signal of each subcarrier block and output the calculated power value to CIR calculation sections 303-1 to 303-3.

  The CIR calculation units 303-1 to 303-3 calculate the ratio of the desired signal and the interference signal and output it to the CQI generation unit 213.

  As described above, according to the communication terminal apparatus of the present embodiment, the frequency hopped received signal is restored to the original signal in units of subcarrier blocks, so that it is possible to achieve good propagation while reducing other cell interference by hopping. The frequency of the situation can be used and it can be transmitted at high speed.

  Note that the transmission HARQ units 105-1 and 105-2 and the reception HARQ unit 208 in the above description may be omitted. A case where communication is performed using a fixed MCS is also conceivable.

(Embodiment 2)
FIG. 5 is a block diagram showing the configuration of the base station apparatus according to Embodiment 2 of the present invention. 1 identical to those in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed descriptions thereof are omitted.

  The base station apparatus 400 of FIG. 5 includes a control data processing unit 401, a subcarrier block selection unit 402, and a subcarrier block hopping sequence generation unit 403, and a channel that continuously transmits at a low rate such as a control channel and voice. 1 differs from the base station apparatus of FIG. 1 in that the subcarrier block is hopped. The control data processing unit 401 mainly includes an encoding unit 411 and a modulation unit 412.

  In FIG. 5, an encoding unit 411 encodes control data, audio data, a broadcast signal, and a multicast signal and outputs the encoded data to the modulation unit 412. Modulation section 412 modulates the control data, audio data, broadcast signal, and multicast signal and outputs the result to subcarrier block selection section 402.

  Subcarrier block selection section 402 assigns a subcarrier block instructed by scheduler section 102 to each user signal, and hopping patterns are selected by FH sequence selection sections 111-1 to 111-n for the respective subcarrier blocks.

  Furthermore, the subcarrier block selection unit 402 receives the hopping sequence of the subcarrier block from the subcarrier block hopping sequence generation unit 403 and outputs the control data, audio data, broadcast signal, and multicast signal output from the modulation unit 412. Are assigned subcarrier blocks according to this hopping sequence. Also for this subcarrier block, the hopping pattern is selected by the FH sequence selection units 111-1 to 111-n in the same manner as the user signal.

  Subcarrier block hopping sequence generation section 403 generates a sequence (pattern) for hopping a subcarrier block to which control data is mapped every moment. Here, a predetermined sequence is generated for each base station. The subcarrier block selection unit 402 is instructed to assign a subcarrier block to control data in the current transmission unit according to the generated sequence.

  FIG. 6 is a diagram illustrating a subcarrier mapping example of the base station apparatus according to the present embodiment. In FIG. 6, the horizontal axis indicates the frequency of the subcarrier, and the vertical axis indicates the time in frame units.

  As shown in FIG. 6, the control data (and also the audio data, the broadcast signal, and the multicast signal) are frequency hopped in units of subcarrier blocks. Then, a subcarrier block for mapping a signal is determined for each frame.

  As described above, according to the base station apparatus of the present embodiment, the frequency diversity effect can be obtained by hopping the subcarrier block as well as the channel continuously transmitted at a low rate such as the control channel and the voice, and the uniform and stable. Reception quality is obtained, and voice quality is improved.

  In addition, when transmission using scheduling is performed on a low-rate signal, the signal amount ratio (overhead ratio) of the control signal increases, which is not efficient. Therefore, the method of hopping subcarrier blocks can be transmitted efficiently.

  Also, broadcast information, multicast information, and subcarrier blocks used for news distribution are hopped. As a result, the reception quality of information transmitted to many users is improved due to the frequency diversity effect.

(Embodiment 3)
The user at the cell boundary has strong interference from adjacent cells. Since users in other cells do not know which subcarrier block will be assigned next, the amount of interference cannot be predicted. Therefore, a user at a cell boundary may have a large amount of interference at the next moment even for a subcarrier block with a small amount of interference and a high CIR at the present moment. Therefore, in this embodiment, when CIR is measured as the reception quality fed back by the communication terminal apparatus, the signal power (C) uses the measured value for each block, and the interference power (I) is the interference power of each block. Use the average value.

  FIG. 7 is a diagram showing a configuration of a CIR measurement unit of the base station apparatus according to Embodiment 3 of the present invention. 4 identical to those in FIG. 4 are assigned the same reference numerals as in FIG. 4 and detailed descriptions thereof are omitted. The CIR measurement unit in FIG. 7 includes an interference power averaging unit 601 and CIR calculation units 602-1 to 602-3, which calculates an average value of interference power and calculates CIR from the average value. 4 different from the CIR measurement unit.

  Signal power calculation sections 301-1 to 301-3 calculate power values of desired signals of the respective subcarrier blocks, and output the calculated power values to CIR calculation sections 602-1 to 602-3.

  Interference power calculation sections 302-1 to 302-3 calculate the power value of the interference signal of each subcarrier block and output it to interference power averaging section 601.

  The interference power averaging unit 601 calculates the average value of the power of the interference signal calculated by the interference power calculation units 302-1 to 302-3 and outputs the average value to the CIR calculation units 602-1 to 602-3.

  The CIR calculation units 602-1 to 602-3 obtain the ratio of the average value of the power of the desired signal and the interference signal and output it to the CQI generation unit 213.

  Thus, according to the communication terminal apparatus of the present embodiment, the interference power of the received signal is measured for each subcarrier block, the average value of the interference power of a plurality of subcarrier blocks is obtained, and the desired value of each subcarrier block is determined. By calculating the ratio of the signal power value and the average value of interference power as CIR, the influence of unpredictable changes in interference can be reduced and more accurate channel reception quality can be measured. It becomes possible to select by the station apparatus, and the throughput is improved. It also leads to the selection of a more optimal MCS.

(Embodiment 4)
In the fourth embodiment, an example in which the size of the subcarrier block is variable for each cell will be described.

  Generally, a cell with a small cell radius is arranged in a city area because the user density is high, and a cell with a large cell radius is arranged in a suburb. In the case of a small cell, the delay dispersion is small (1 μs or less), and in the case of a large cell, the delay dispersion is large (5 μs or more).

  8 and 9 are diagrams illustrating examples of fading fluctuations. 8 and 9, the horizontal axis indicates the frequency used for communication, and the vertical axis indicates the magnitude of fading fluctuation.

  FIG. 8 is an example when the delay dispersion is large. As shown in FIG. 8, when the delay dispersion is large, the fading change in the frequency direction is significant, and unless the subcarrier block size is kept small, the received power changes within the block. An optimal subcarrier allocation according to quality cannot be performed. In general, the MCS is determined from the CIR on the assumption that the reception quality is almost constant. However, if the fading fluctuation is large in the block, the accuracy of the MCS selection is also deteriorated.

  FIG. 9 is an example when the delay dispersion is small. As shown in FIG. 9, when delay dispersion is small, there is little change in fading in the frequency direction, so there is no problem even if the subcarrier block is relatively large. On the other hand, if the subcarrier block is too small, the amount of control signals such as reporting of reception quality of the subcarrier block and downlink allocation information will increase. From these considerations, it is considered that the subcarrier block size has an optimum value according to the cell radius.

  Therefore, in the fourth embodiment, the block size is variable for each cell, and a value corresponding to the cell size is set. FIG. 10 is a diagram showing the concept of the fourth embodiment of the present invention. The upper left cell A, the lower left cell B is a small cell, and the upper right cell C is a large cell. Cell A and cell B are set to a total of four blocks by increasing the block size. Cell C is set to a total of 8 blocks by reducing the block size. The control station 701 notifies the base station apparatuses 702, 703, and 704 of the block size of each cell. The control station 701 notifies the base station devices 702, 703, and 704 as broadcast information. In each cell, the processing of the first to third embodiments is operated with the notified block size.

  Here, comparing control signal amounts, in the uplink, there is CQI (for example, 6 bits) of each subcarrier block measured by the communication terminal apparatus. Since cells A and B are for 4 blocks, 24 bits are sufficient, but cell C requires 48 bits.

  In the downlink, there is information on which subcarrier block to use, but since cells A and B are for 4 blocks, 4 bits are sufficient, but for cell C, 8 bits are required because they are for 8 blocks. (In the case of a system capable of assigning a plurality of subcarrier blocks.)

  Furthermore, it is necessary to send MCS (for example, 6 bits) of each subcarrier block. In cells A and B, 4 × 6 = 24 bits are sufficient, but in cell C, 8 × 6 = 48 bits are required. Although the amount of control information increases in the cell C, high-accuracy control according to the fading fluctuation in the frequency direction can be performed accordingly.

  Next, the internal configuration of the base station apparatus according to the present embodiment will be described. FIG. 11 is a block diagram showing configurations of the base station apparatus and the control station apparatus according to the present embodiment. 1 identical to those in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed descriptions thereof are omitted.

  The base station apparatus 800 of FIG. 11 includes a receiving unit 801, a delay dispersion calculating unit 802, and a block size information receiving unit 803. When the delay dispersion of the propagation path is large, the block is made small, and when the delay dispersion is small. Is different from the base station apparatus of FIG. The control station apparatus 850 in FIG. 11 mainly includes a delay information receiving unit 851, a block size determining unit 852, and a transmitting unit 853.

  Receiving section 801 receives a received signal transmitted from a communication terminal apparatus that is a communication partner, converts the frequency of the received signal into a baseband signal, decodes it, and extracts CQI information. Then, the reception unit 801 outputs the CQI information to the scheduler unit 804 and the MCS determination unit 103. The receiving unit 801 also outputs the received signal to the delay dispersion calculating unit 802.

  The delay dispersion calculation unit 802 calculates the magnitude of the delay dispersion of the propagation path from the received signal and outputs it to the delay information reception unit 851.

  Delay information receiving section 851 receives delay dispersion information output from base station apparatus 800 and outputs the information to block size determining section 852. Note that the received delay dispersion information is delay dispersion information output from a plurality of base station apparatuses as shown in FIG.

  Based on the delay dispersion information output from a plurality of base stations, the block size determination unit 852 makes a cell with a large delay dispersion of the propagation path a small block and a cell with a small delay dispersion a large block. Here, a small block indicates a subcarrier block having a small number of subcarriers, and a large block indicates a subcarrier block having a large number of subcarriers.

  The transmission unit 853 outputs the block size information determined by the block size determination unit 852 to the block size information reception unit 803 of each base station apparatus.

  Block size information reception section 803 outputs the received block size information to scheduler section 804 and subcarrier block selection section 805.

  The scheduler unit 804 performs scheduling for determining which user to transmit using CQI (Channel Quality Information) from each communication terminal apparatus, and selects a user signal to be transmitted in the next frame. There are algorithms such as MaxC / I and Round Robin. At this time, scheduler section 804 determines which subcarrier block is to be transmitted among the subcarrier blocks having the block size determined by block size determination section 852, and outputs the result to subcarrier block selection section 805. Here, scheduler section 804 selects the subcarrier block of the best propagation path.

  The subcarrier block selection unit 805 selects a subcarrier block instructed by the scheduler unit 804 from among the subcarrier blocks having the block size determined by the block size determination unit 852, and selects FH for each subcarrier block. A hopping pattern is selected by sequence selection sections 111-1 to 111-n.

  As described above, according to the control station apparatus and the base station apparatus of the present embodiment, the signal amount is reduced by making the cell with a large delay dispersion of the propagation path into a small block and the cell with a small delay dispersion into a large block. can do.

  Note that the control station apparatus and base station apparatus of the embodiment can be applied not only to the FH-OFDM scheme but also to other multicarrier communication schemes. Further, the control station apparatus and the base station apparatus can be integrated, and the block size can be determined from the delay dispersion of one base station apparatus.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. For example, in the above embodiment, the case of performing as a base station apparatus has been described, but the present invention is not limited to this, and this wireless communication method can also be performed as software.

  For example, a program for executing the wireless communication method may be stored in advance in a ROM (Read Only Memory), and the program may be operated by a CPU (Central Processor Unit).

  In addition, a program for executing the wireless communication method is stored in a computer-readable storage medium, the program stored in the storage medium is recorded in a RAM (Random Access Memory) of the computer, and the computer operates according to the program. You may make it let it.

The block diagram which shows the structure of the base station apparatus which concerns on Embodiment 1 of this invention. The figure which shows the example of mapping of the subcarrier of the base station apparatus of the said embodiment The block diagram which shows the structure of the communication terminal device of the said embodiment The block diagram which shows the structure of the CIR measurement part of the communication apparatus of the said embodiment. The block diagram which shows the structure of the base station apparatus which concerns on Embodiment 2 of this invention. The figure which shows the example of mapping of the subcarrier of the base station apparatus of the said embodiment The figure which shows the structure of the CIR measurement part of the base station apparatus which concerns on Embodiment 3 of the said invention. Diagram showing an example of fading fluctuation Diagram showing an example of fading fluctuation The figure which shows the concept of Embodiment 4 of this invention. The block diagram which shows the structure of the base station apparatus of the said embodiment, and a control station apparatus The block diagram which shows the structure of the conventional base station apparatus The block diagram which shows the structure of the transmission HARQ part of the conventional base station apparatus. The figure which shows an example of the signal of the conventional base station apparatus The block diagram which shows the structure of the conventional mobile station apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Reception part 102 Scheduler part 103 MCS determination part 110,402 Subcarrier block selection part 111-1 to 111-n FH sequence selection part 112 Subcarrier mapping part 113 S / P conversion part 114 IFFT part 203 FFT part 204 Subcarrier block Extraction unit 205-1, 205-2 Data sequence reproduction unit 211 Pilot signal extraction unit 212 CIR measurement unit 213 CQI generation unit 214 Transmission unit 301-1 to 301-3 Signal power calculation unit 302-1 to 302-3 Interference power calculation Units 303-1 to 303-3, 602-1 to 602-3 CIR calculation unit 601 Interference power averaging unit 802 Delay dispersion calculation unit 803 Block size information reception unit 851 Delay information reception unit 852 Block size determination unit 853 Transmission unit

Claims (4)

A base station apparatus that performs wireless communication using a multicarrier communication band divided into a plurality of blocks,
While assigning any one of the plurality of blocks to the first transmission data based on the communication quality for each block, the second transmission data different from the first transmission data has a predetermined pattern based on the communication quality for each block. Assigning means for assigning any of the plurality of blocks according to:
Hopping means for frequency hopping the first transmission data and the second transmission data assigned to each block within each block;
A base station apparatus comprising: The first transmission data is transmission data that is encoded and modulated according to communication quality;
The second transmission data is transmission data that is encoded and modulated regardless of communication quality.
The base station apparatus according to claim 1. The communication quality is a CIR for each block calculated from the power of the desired signal for each block and the average value of the power of the interference signal over the plurality of blocks.
The base station apparatus according to claim 1. A wireless communication method using a multicarrier communication band divided into a plurality of blocks,
While assigning any one of the plurality of blocks to the first transmission data based on the communication quality for each block, the second transmission data different from the first transmission data has a predetermined pattern based on the communication quality for each block. Assign any of the plurality of blocks according to
Frequency hopping the first transmission data and the second transmission data assigned to each block within each block;
Wireless communication method.

Images