JP4546220B2 - Multi-antenna communication apparatus and cell selection method - Google Patents

Description

  The present invention relates to a multi-antenna communication apparatus and a cell selection method, and more particularly to a multi-antenna communication apparatus and a cell selection method for selecting a base station apparatus to be a communication partner in a short cycle such as a slot when located near a cell boundary. About.

  In recent years, when a mobile station device is located in an area near the boundary of a plurality of cells, a high-speed cell that switches a base station device that is a communication partner at high speed in a short period such as a slot according to instantaneous reception level fluctuations Performing selection (FCS: Fast Cell Selection) has been studied (for example, see Non-Patent Document 1).

  FIG. 13A is a diagram illustrating an example of a cell selection operation by FCS. As shown in the figure, the mobile station device 10 switches the communication partner of the base station device 20 and the base station device 30 in order from the top slot 40.

  Specifically, the mobile station apparatus 10 receives a common pilot channel signal (hereinafter referred to as “common pilot signal”) transmitted from the base station apparatus 20 and the base station apparatus 30, and receives a received SIR (Signal to Interference). Ratio: Signal wave to interference wave ratio) is measured. The measurement result is shown in FIG. In the figure, the solid line indicates the reception SIR of the signal from the base station apparatus 20, and the dotted line indicates the reception SIR of the signal from the base station apparatus 30.

  Then, the mobile station apparatus 10 selects a base station apparatus having a large reception SIR for each slot, and transmits information on the selected base station apparatus (hereinafter referred to as “selected base station apparatus”) to the base station apparatus 20 and the base station apparatus. 30. Here, the selected base station apparatus for each slot is indicated by a solid line (that is, base station apparatus 20) and a dotted line (that is, base station apparatus 30) in the lower part of FIG.

  The base station device 20 and the base station device 30 receive information related to the selected base station device from the mobile station device 10, and the selected base station device for each slot is assigned to an individual channel or a high-speed channel in the slot indicated by hatching in FIG. Data signals such as packet channels (hereinafter referred to as “individual data signals”) are transmitted.

  As described above, the mobile station apparatus 10 located in the region near the boundary of the cell switches the selected base station apparatus (that is, selects the cell) in a short period, thereby improving the reception quality and throughput in the mobile station apparatus 10. be able to.

On the other hand, MIMO (Multi Input Multi Output) communication has been actively studied as a technique for improving throughput. In MIMO communication, a high transmission rate can be realized by simultaneously transmitting different data sequences between a plurality of transmission / reception antennas (see, for example, Non-Patent Document 2).
"Physical layer aspects of UTRA High Speed Downlink Packet Access" (Section 6.4), 3GPP TR25.848 V4.4.0 (2001-03) "Signal processing in MIMO system", Hokkaido University, 2003 IEICE Society Conference TB-2-3, September 2003

  However, in MIMO communication, even if the selected base station apparatus is switched by FCS as described above, reception quality and throughput cannot always be improved.

  That is, in MIMO communication in which signals are transmitted using a plurality of paths having low correlation with each other, since signals of all paths are mixed in the received signal, the signals of each path weaken or strengthen each other. Sometimes. Therefore, there is a problem that even if a base station apparatus is simply selected based on the reception SIR of the received signal, reception quality and throughput may not be improved. If the reception quality and throughput are not improved, the distance from the base station apparatus that can achieve the target throughput does not increase, and as a result, the area covered by each base station apparatus (hereinafter referred to as “cell”). Expansion of coverage) is difficult.

  Furthermore, in MIMO communication, a complex reception process is performed in order to separate spatially multiplexed signals on the receiving side. For this reason, it is desirable to minimize the increase in circuit scale required for high-speed cell selection.

  The present invention has been made in view of the above points, and performs a high-speed cell selection while preventing an increase in circuit scale, and can reliably improve throughput and expand cell coverage. The purpose is to provide a selection method.

  The multi-antenna communication apparatus according to the present invention receives a signal of a connection cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connection cell via a plurality of antennas at a predetermined sample timing. Means for calculating channel capacity of the connected cell using the signal of the connected cell, and timing selection for selecting one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled Means, a second calculating means for calculating the channel capacity of the observation cell for the selected sample timing, and comparing the channel capacity of the connected cell and the channel capacity of the observation cell to determine the cell with the largest channel capacity. Cell selection means for selecting as a connected cell in the next time unit A configuration.

  The cell selection method according to the present invention includes a step of sampling a signal of a connection cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connection cell via a plurality of antennas at a predetermined sample timing; Calculating the channel capacity of the connected cell using the signal of the connected cell, selecting one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled, and the selected sample The step of calculating the channel capacity of the observation cell with respect to timing is compared with the channel capacity of the connection cell and the channel capacity of the observation cell, and the cell having the largest channel capacity is selected as the connection cell in the next time unit. Steps.

  According to these, while calculating the channel capacity of the connected cell, the channel capacity of the observation cell is calculated by selecting one or more sample timings from the sample timing of the signal of the observation cell. Because it is a connected cell, it can reduce the amount of processing required to calculate the channel capacity of the observation cell, perform high-speed cell selection while preventing an increase in circuit scale, and improve cell throughput by reliably improving throughput. Can be enlarged.

  According to the present invention, it is possible to perform high-speed cell selection while preventing an increase in circuit scale, to reliably improve throughput and to expand cell coverage.

  The essence of the present invention is that a base station apparatus of a cell having many independent paths that can be used for MIMO communication by selecting a sample timing with high reception power from a sampling interval of a reception signal and using a signal of only the selected sampling timing Is to select.

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

(Embodiment 1)
FIG. 1 is a diagram showing an example of a configuration of a mobile communication system according to Embodiment 1 of the present invention. As shown in the figure, the multi-antenna communication apparatus 100 located in the region near the boundary between the cell 200a covered by the base station apparatus 200 and the cell 300a covered by the base station apparatus 300 includes the base station apparatus 200 and the base station apparatus. 300 Common pilot channel signals (common pilot signals) transmitted from both antennas are received. In addition, the multi-antenna communication apparatus 100 switches either the base station apparatus 200 or the base station apparatus 300 as a communication partner for each short time unit such as a slot.

  FIG. 2 is a block diagram showing a main configuration of multi-antenna communication apparatus 100 according to the present embodiment. A multi-antenna communication apparatus 100 shown in FIG. 2 includes RF (Radio Frequency) receiving units 101-1 and 101-2, a path search unit 102, despreading units 103-1 and 103-2, a cell separation unit 104, Connected cell reception processing unit 105, observed cell reception processing unit 106, cell selection unit 107, multiplexing unit 108, error correction coding unit 109, modulation unit 110, spreading units 111-1, 111-2, and RF transmission unit 112- 1, 112-2. In the present embodiment, multi-antenna communication apparatus 100 is configured to have two antennas. However, when there are three or more antennas, an RF receiver, a despreader, a spreader, and an RF transmitter Each processing section is provided corresponding to the antenna.

  The RF receivers 101-1 and 101-2 sample the received signal at a sample timing of a predetermined sampling rate, and perform predetermined wireless reception processing (down-conversion, A / D conversion, etc.) on the received signal.

  The path search unit 102 performs a path search that estimates and separates the arrival directions of signals received by the RF receiving units 101-1 and 101-2 from a plurality of paths.

  The despreading sections 103-1 and 103-2 despread the signal of each path using the spreading code and scrambling code corresponding to each cell based on the path search result, and cell separation is performed on the obtained despread signal. Output to the unit 104.

  The cell separation unit 104 separates the despread signal into signals for each cell. Specifically, the cell separation unit 104 is adjacent to the cell of the base station apparatus (hereinafter referred to as “connected cell”) that is currently the communication partner of the multi-antenna communication apparatus 100, and is connected to the multi-antenna communication apparatus 100. The despread signal is separated into a signal of a cell (hereinafter referred to as “observation cell”) having a boundary with the connected cell in the vicinity of the position of the antenna communication device 100. Note that when there are a plurality of observation cells, the cell separation unit 104 separates the despread signal into the signals of the respective observation cells.

  The connected cell reception processing unit 105 performs reception processing on the signal of the connected cell and outputs received data. Connected cell reception processing section 105 measures radio quality from the signal of the connected cell and outputs radio quality information to multiplexing section 108. Furthermore, the connected cell reception processing unit 105 performs singular value decomposition processing in the course of reception processing on the signal of the connected cell, calculates the channel capacity of the connected cell, and outputs the calculated channel capacity to the cell selection unit 107.

  Here, the singular value is an index indicating the reception quality for each independent path through which a spatially multiplexed signal is transmitted in MIMO communication, and the singular value decomposition process is a process of reception processing in MIMO communication. A process for calculating a singular value for each independent path using the estimation result. The channel capacity is an index indicating whether each cell is suitable for performing MIMO communication. In MIMO communication, the more independent paths that have no correlation and high reception quality, the higher the possibility that a spatially multiplexed signal can be separated on the receiving side. Therefore, a cell with many paths with a large singular value has a larger channel capacity and can be said to be a cell suitable for MIMO communication. The detailed configuration of the singular value, the channel capacity, and the connected cell reception processing unit 105 will be described in detail later.

  Observation cell reception processing section 106 performs reception processing on the signal of the observation cell, calculates the channel capacity of the observation cell, and outputs it to cell selection section 107. Here, since the base station apparatus of the observation cell is not a communication partner of multi-antenna communication apparatus 100, observation cell reception processing section 106 performs reception processing on the common pilot signal in the observation cell. For the observation cell, the channel capacity is not calculated for all sections of the sampled common pilot signal, but the channel capacity is calculated only for the sampling timing at which the total received power is high. For this reason, the processing load of channel capacity calculation in the observation cell reception processing unit 106 can be reduced. The detailed configuration of the observation cell reception processing unit 106 will be described in detail later.

  The cell selection unit 107 compares the channel capacity of the connected cell and the channel capacity of the observation cell, and sets the base station apparatus of the cell having a large channel capacity as the communication partner base station apparatus (selected base station apparatus). That is, the cell selection unit 107 sets a cell having the largest channel capacity as a connection cell in the next time unit. Then, cell selection section 107 outputs cell selection information related to the selected base station apparatus to multiplexing section 108.

  Multiplexing section 108 multiplexes cell selection information, radio quality information, transmission data, etc., and outputs the obtained multiplexed data to error correction coding section 109.

  Error correction coding section 109 performs error correction coding on the multiplexed data and outputs the obtained coded data to modulation section 110.

  Modulating section 110 modulates the encoded data and outputs the obtained modulated data to spreading sections 111-1 and 111-2.

  Spreading sections 111-1 and 111-2 spread the modulated data and output the obtained spread signals to RF transmitting sections 112-1 and 112-2.

  The RF transmitters 112-1 and 112-2 perform predetermined radio transmission processing (D / A conversion, up-conversion, etc.) on the spread signal, and transmit from each corresponding antenna.

  FIG. 3 is a block diagram showing an internal configuration of connected cell reception processing section 105 according to the present embodiment.

Channel estimation section 1051 performs channel estimation for each path corresponding to the antenna pair on the transmission / reception side using the common pilot signal of the connected cell. Here, if the number of antennas of multi-antenna communication apparatus 100 (reception side) is M _{R and the} number of antennas of base station apparatus 200 and base station apparatus 300 (transmission side) is M _T (≧ M _R ), As a result of the estimation, a channel matrix having a size of M _R × M _T is obtained for each sample timing in the RF receivers 101-1 and 101-2. That is, if the transmission signal vector from the base station apparatus corresponding to the sample timing i is x _i (t) and the noise signal vector in the propagation path is n _i (t), the multi-antenna communication apparatus 100 receives the sample timing i. The signal vector r _i (t) can be expressed by the following equation (1) using the channel matrix A _i .

r _i (t) = A _i x _i (t) + n _i (t) (1)
The channel estimation unit 1051 obtains a channel matrix A _i for each sample timing that satisfies the above equation (1) for the connected cell. Although it may be different from the number of antennas of the number of antennas and the base station apparatus 300 of the base station apparatus 200, where as those having convenience, any of the M _T antennas base station apparatus description To do.

Demodulation section 1052 has singular value decomposition processing section 1052a, and demodulates the individual data signal of the connected cell. Demodulation section 1052 performs demodulation corresponding to the modulation scheme on the transmission side (base station apparatus 200 or base station apparatus 300), and outputs the demodulated individual data signal to error correction decoding section 1053 and radio quality measurement section 1055. . The singular value decomposition processing unit 1052a performs singular value decomposition processing using the channel matrix A _i in the course of demodulation, and calculates singular values for each independent path in the connected cell for all sample timing signals. Specifically, the singular value decomposition processing unit 1052a calculates the singular value for each independent path of the connected cell at the sample timing i by the following equation (2).

上式（２）において、Ａ_i ^Hはチャネル行列Ａ_iの共役転置行列、Ｕ_iは固有ベクトルを並べて得られるユニタリ行列、Ｕ_i ^Hはユニタリ行列Ｕ_iの共役転置行列を示している。また、diag（）は対角行列を示しており、上式（２）においては行列Λ_iの対角成分にＭ_R個の特異値λ_i,1〜λ_i,ＭRが現れている。なお、ここではＭ_T≧Ｍ_Rと仮定したため、Ｍ_R個の特異値が求められるが、Ｍ_T＜Ｍ_Rの場合は、Ｍ_T個の特異値が求められる。

In the above equation (2), A _i ^H is a conjugate transpose matrix of the channel matrix A _i , U _i is a unitary matrix obtained by arranging eigenvectors, and U _i ^H is a conjugate transpose matrix of the unitary matrix U _i . Also, diag () denotes a diagonal matrix, M _R singular values in the diagonal elements of the matrix lambda _i in the above equation _{(2) λ i, 1 ~λ} i, MR has appeared. Here, since it is assumed that M _T ≧ M _R , M _R singular values are obtained. However, when M _T <M _R , M _T singular values are obtained.

  Error correction decoding section 1053 performs error correction decoding on the demodulated individual data signal in accordance with the coding rate on the transmission side (base station apparatus 200 or base station apparatus 300), and separates the individual data signal after error correction decoding Output to the unit 1054.

  Separating section 1054 separates the individual data signal after error correction decoding into received data and radio resource allocation information indicating the modulation scheme and coding rate on the transmitting side (base station apparatus 200 or base station apparatus 300), and receives the received data Is output to the demodulator 1052 and the error correction decoder 1053.

  Radio quality measuring section 1055 measures the radio quality in the connected cell using the common pilot signal of the connected cell, and outputs the radio quality information to multiplexing section 108.

The singular value processing unit 1056 processes the singular value obtained for each sample timing and for each independent path, and calculates a singular value representing each independent path. That is, the singular value processing unit 1056 has, for example, all the singular values λ _{1,1 to} λ _{1 , MR} , λ _{2,1 to} λ _{2, MR} ,. For λ _{i, 1 to} λ _{i, MR} ,..., λ _{N, 1 to} λ _{N, MR ,} the sum of singular values λ _{1, j to} λ _{N, j} for each independent path j is the total number of sample timings N The singular values λ _{1 to} λ _MR that represent the independent paths are calculated by dividing by. As a result, one singular value λ _j corresponds to one independent path j.

The channel capacity calculation unit 1057 compares the singular values λ _{1 to} λ _MR for each independent path obtained by the singular value processing unit 1056 with a predetermined threshold value, and determines the number of singular values equal to or greater than the predetermined threshold value in the channel of the connected cell. Calculate as capacity. As described above, the singular value indicates the reception quality of each independent path in the MIMO communication. In MIMO communication, as the number of paths with high reception quality increases, signals transmitted simultaneously from a plurality of antennas can be more accurately separated. Therefore, the greater the number of singular values equal to or greater than a predetermined threshold, the greater the throughput. It will be expensive. The channel capacity calculation unit 1057 outputs the calculated channel capacity of the connected cell (that is, the number of singular values greater than or equal to a predetermined threshold) to the cell selection unit 107.

  FIG. 4 is a block diagram showing an internal configuration of observation cell reception processing section 106 according to the present embodiment.

  The channel estimation unit 1061 performs channel estimation for each path corresponding to the antenna pair on the transmission / reception side using the common pilot signal of the observation cell, and obtains the channel matrix of the observation cell.

From the channel estimation result obtained by the channel estimation unit 1061, the timing selection unit 1062 performs the sampling for each sample timing in each antenna pair of the antenna of the multi-antenna communication apparatus 100 (reception side) and the antenna of the base station apparatus (transmission side) of the observation cell. Received power is calculated, and a sample timing at which the total received power of all antenna pairs is equal to or greater than a predetermined threshold is selected as a sample timing for singular value decomposition processing. That is, the timing selection unit 1062 receives reception power of signals from M _T transmitting-side antennas received at M _R receiving-side antennas for one sample timing (ie, M _R × 1 for one sample timing). M _T received power) is added to calculate the total received power for each sample timing, and the sample timing with the total received power equal to or greater than a predetermined threshold is selected.

  Unlike the signal of the connected cell, only the common pilot signal is received as the signal of the observation cell and is not demodulated. Therefore, the singular value decomposition process is performed at the stage of the reception process of the signal of the observation cell. Absent. Therefore, for the observation cell, it is necessary to perform singular value decomposition processing only for cell selection. At this time, as described above, by selecting a sample timing that is equal to or greater than a predetermined threshold and performing singular value decomposition processing only for this sample timing, the processing load of singular value decomposition processing can be reduced.

  Also, regarding the sample timing with the total received power equal to or greater than a predetermined threshold, the channel matrix is accurately obtained, so that the result of the singular value decomposition process is considered to be accurate. As a result, the channel capacity of the observation cell can be accurately calculated with a small amount of processing.

  Note that the timing selection unit 1062 may select a predetermined number of sample timings from the higher total received power, instead of selecting sample timings whose total received power is greater than or equal to a predetermined threshold. In this case, the number of sample timings to be subjected to singular value decomposition processing is always constant, and even when the received power is low as a whole, the sample timing to be subjected to singular value decomposition processing is reliably selected.

  The path synthesis unit 1063 obtains a channel matrix when the signals of the paths corresponding to the selected sample timing are synthesized, and outputs this channel matrix to the singular value decomposition processing unit 1064.

  The singular value decomposition processing unit 1064 uses the channel matrix output from the path synthesis unit 1063 to perform the singular value decomposition processing according to Expression (2) in the same manner as the connected cell, and only the sample timing selected by the timing selection unit 1062 is obtained. The singular value for each independent path in the observation cell is calculated.

  The channel capacity calculation unit 1065 compares the singular value for each independent path output from the singular value decomposition processing unit 1064 with a predetermined threshold value, and calculates the number of singular values greater than or equal to the predetermined threshold value as the channel capacity of the observation cell. .

  FIG. 5 is a block diagram showing a main configuration of base station apparatus 200 according to the present embodiment. The base station apparatus 200 shown in FIG. 5 includes RF receiving units 201-1 and 201-2, a path search unit 202, despreading units 203-1 and 203-2, a demodulation unit 204, an error correction decoding unit 205, and a separation unit 206. A resource allocation unit 207, a transmission control unit 208, a multiplexing unit 209, an error correction coding unit 210, a modulation unit 211, spreading units 212-1, 212-2, and RF transmission units 213-1 and 213-2 ing. The base station apparatus 300 has the same configuration as the base station apparatus 200.

  The RF receivers 201-1 and 201-2 receive signals from the corresponding antennas, respectively, and perform predetermined wireless reception processing (down-conversion, A / D conversion, etc.) on the received signals.

  The path search unit 202 performs a path search that estimates and separates the arrival directions of signals received by the RF reception units 201-1 and 201-2 from a plurality of paths.

  Despreading sections 203-1 and 203-2 despread each path signal from the path search result, and output the obtained despread signal to demodulation section 204.

  Demodulation section 204 demodulates the despread signal and outputs the obtained demodulated signal to error correction decoding section 205.

  Error correction decoding section 205 performs error correction decoding on the demodulated signal and outputs the signal after error correction decoding to separation section 206.

  Separation section 206 separates the signal after error correction decoding into reception data, cell selection information, and radio quality information, outputs reception data, and outputs cell selection information and radio quality information to resource allocation section 207.

  The resource allocation unit 207 refers to the cell selection information to determine whether or not the own device (base station device 200) has become the selected base station device, and refers to the radio quality information if it has become the selected base station device. Wireless resources to be allocated to transmission data addressed to the multi-antenna communication apparatus 100 are determined.

  The transmission control unit 208 controls the transmission order of transmission data to the multi-antenna communication apparatus 100 and other communication apparatuses, and generates radio resource allocation information indicating a modulation scheme and a coding rate corresponding to the transmission data.

  Multiplexer 209 multiplexes transmission data, radio resource allocation information, a common pilot signal (not shown), and the like, and outputs the obtained multiplexed data to error correction encoder 210.

  Error correction coding section 210 performs error correction coding on the multiplexed data at a coding rate corresponding to each transmission destination, and outputs the obtained coded data to modulation section 211.

  Modulation section 211 modulates the encoded data with a modulation scheme corresponding to each transmission destination, and outputs the obtained modulation data to spreading sections 212-1 and 212-2.

  Spreading sections 212-1 and 212-2 spread modulated data, and output the obtained spread signals to RF transmission sections 213-1 and 213-2.

  The RF transmitters 213-1 and 213-2 perform predetermined wireless transmission processing (D / A conversion, up-conversion, etc.) on the spread signal, and transmit from each corresponding antenna.

  Next, cell selection by the multi-antenna communication apparatus 100 configured as described above will be described with reference to the sequence diagrams shown in FIGS. 6A and 6B, divided into operations at the start of communication and during communication. .

  First, an operation at the start of communication, such as when the multi-antenna communication apparatus 100 is turned on, will be described with reference to FIG. When the multi-antenna communication apparatus 100 is located near the boundary between the cell 200a of the base station apparatus 200 and the cell 300a of the base station apparatus 300, the RF receiving units 101-1 and 101-2 of the multi-antenna communication apparatus 100 perform the base station Common pilot signal 401 and individual data signal 402 from apparatus 200 and common pilot signal 403 and individual data signal 404 from base station apparatus 300 are sampled at a predetermined sample timing.

  The received signal obtained by sampling is subjected to predetermined radio reception processing by the RF receiving units 101-1 and 101-2, path search is performed by the path search unit 102, and despreading units 103-1 and 103-. By performing the despreading by 2, the despread signal addressed to the own device (multi-antenna communication device 100) is extracted.

  The despread signal is separated into the signal of the connection cell and the signal of the observation cell by the cell separation unit 104, but here there is no connection cell because it is at the start of communication, and both the cell 200a and the cell 300a are both observation cells. It is. Therefore, the signals of both the cell 200a and the cell 300a are output to the channel estimation unit 1061 of the observation cell reception processing unit 106.

  Then, the channel estimation unit 1061 obtains the channel matrix of the cell 200a and the channel matrix of the cell 300a, respectively, and the timing selection unit 1062 selects a sample timing at which the total received power is greater than or equal to a predetermined threshold value in each cell ( 405).

  Specifically, for example, the base station apparatus 200 has two antennas, a transmission antenna # 1 and a transmission antenna # 2, and the multi-antenna communication apparatus 100 has two antennas, a reception antenna # 1 and a reception antenna # 2. If so, the timing selection unit 1062 adds the received power for each sample timing of each pair of the transmitting antenna and the receiving antenna, as shown in FIG. 7, and obtains the total received power. Then, the timing selection unit 1062 selects a sample timing P and a sample timing Q whose total received power is equal to or greater than a predetermined threshold. Similarly, the timing selection unit 1062 selects a sample timing at which the total received power is equal to or greater than a predetermined threshold for the cell 300a of the base station device 300.

  The sample timing selected for each cell is notified to the path synthesis unit 1063, and the path synthesis unit 1063 obtains a channel matrix when the signals of the paths corresponding to the selected sample timing are synthesized. In other words, the path synthesizing unit 1063 obtains a channel matrix when it is assumed that a signal having a sample timing with a large total received power is one signal. The obtained channel matrix is output to the singular value decomposition processing unit 1064.

  Then, the singular value decomposition processing unit 1064 uses the channel matrix output from the path synthesis unit 1063 to perform the singular value decomposition processing according to Expression (2), and for each of the cells 200a and 300a, for each independent path. A singular value is determined.

  In this way, by selecting and limiting the sample timings to be subjected to the singular value decomposition process, an increase in processing load due to the singular value decomposition process can be suppressed to a minimum, while preventing an increase in circuit scale. Fast cell selection can be performed. In addition, when selecting the sample timing, the singular value decomposition processing using an accurate channel matrix can be performed by selecting the sample timing with the total received power equal to or greater than a predetermined threshold, and the obtained singular value is also accurate. Become a thing.

  Then, the channel capacity calculation unit 1065 calculates the number of singular values equal to or greater than a predetermined threshold as the channel capacity of each of the cells 200a and 300a (406). The calculated channel capacity is output to the cell selector 107, and the cell 200a and the cell 300a having the larger channel capacity is selected as the connected cell in the next time unit (407), and the base station apparatus corresponding to the connected cell Becomes the selected base station apparatus. Then, the cell selection unit 107 outputs cell selection information related to the cell selected as the connected cell to the multiplexing unit 108. Here, the description will be continued assuming that the cell 200a is selected as the connected cell and the base station apparatus 200 is the selected base station apparatus.

  Here, in the present embodiment, as described above, the singular value decomposition process is performed for the sample timing whose total received power is equal to or greater than the predetermined threshold value, so that the singular value obtained is accurate, and as a result The reliability of channel capacity is also increased. Therefore, the cell 200a selected as the connected cell is more suitable for MIMO communication than the cell 300a, and the throughput can be improved and the cell coverage can be expanded.

  When the cell selection information is input to the multiplexing unit 108, the multiplexing unit 108 multiplexes the transmission data and the cell selection information to generate multiplexed data. The multiplexed data is error correction encoded by the error correction encoding unit 109 and modulated by the modulation unit 110 to obtain modulated data.

  The modulated data is spread by spreading sections 111-1 and 111-2, subjected to predetermined radio transmission processing by RF transmitting sections 112-1 and 112-2, and spread signal 408 including transmission data and cell selection information is received by antenna. Sent through. In FIG. 6A, no signal is transmitted to the base station apparatus 300 that has not been selected, but cell selection information may be transmitted to the base station apparatus 300.

  The spread signal 408 transmitted from the multi-antenna communication apparatus 100 is received by the RF reception units 201-1 and 201-2 of the base station apparatus 200 via the antenna. The received signal is subjected to predetermined radio reception processing by the RF receiving units 201-1 and 201-2, path search is performed by the path search unit 202, and despreading by the despreading units 203-1 and 203-2. As a result, a despread signal addressed to the own apparatus (base station apparatus 200) is extracted.

  The despread signal is demodulated by the demodulator 204, subjected to error correction decoding by the error correction decoding unit 205, and separated into transmission data and cell selection information by the separation unit 206. When cell selection information is output to resource allocation section 207, resource allocation section 207 determines that the own apparatus (base station apparatus 200) has become the selected base station apparatus of multi-antenna communication apparatus 100, and performs multi-antenna communication. Radio resources such as a modulation scheme and a coding rate assigned to transmission data addressed to apparatus 100 are determined (409). The determined radio resource information is output to the transmission control unit 208, and a transmission process of a signal addressed to the multi-antenna communication apparatus 100 is started (410).

  That is, the transmission control unit 208 outputs transmission data addressed to the multi-antenna communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to the multi-antenna communication apparatus 100 to the multiplexing unit 209.

  Then, the multiplexing unit 209 multiplexes the transmission data addressed to the multi-antenna communication apparatus 100 and the radio resource information, and generates multiplexed data. Then, the multiplexed data is subjected to error correction coding by the error correction coding unit 210 and modulated by the modulation unit 211 to obtain modulated data.

  The modulated data is spread by spreading sections 212-1 and 212-2, subjected to predetermined radio transmission processing by RF transmission sections 213-1 and 213-2, and individual data signal 411 including transmission data and radio resource information is generated. Sent via antenna.

  Thus, the signal transmitted from the base station apparatus 200 which is the selected base station apparatus is received by the multi-antenna communication apparatus 100 and received by the connected cell reception processing unit 105 to obtain received data.

  Next, referring to FIG. 6B, the multi-antenna communication apparatus 100 communicates with the base station apparatus 200 as the selected base station apparatus (that is, the cell 200a is the connected cell and the cell 300a is the observation cell). I will explain. When multi-antenna communication apparatus 100 uses cell 200a as a connected cell, common pilot signal 451 and individual data signal 452 from base station apparatus 200 are predetermined by RF receivers 101-1 and 101-2 of multi-antenna communication apparatus 100. Sampled at the sample timing.

  The received signal obtained by sampling is subjected to predetermined radio reception processing by the RF receiving units 101-1 and 101-2, path search is performed by the path search unit 102, and despreading units 103-1 and 103-. By performing the despreading by 2, the despread signal addressed to the own device (multi-antenna communication device 100) is extracted.

  The despread signal is separated into the signal of the connection cell and the signal of the observation cell by the cell separation unit 104. Here, the signal of the cell 200a which is the connection cell is output to the connection cell reception processing unit 105, and the connection cell Is received (453).

  That is, the channel estimation unit 1051 obtains a channel matrix for each sample timing of the cell 200a, and the demodulation unit 1052 demodulates the received signal using the modulation scheme assigned to the multi-antenna communication apparatus 100 in the base station apparatus 200. Singular value decomposition processing by the singular value decomposition processing unit 1052a is performed in the process of demodulation. The singular value for each independent path in the connected cell obtained by the singular value decomposition process is output to the singular value processing unit 1056, while the demodulated individual data signal is output to the error correction decoding unit 1053, and the common pilot signal Is output to the wireless quality measurement unit 1055.

  The individual data signal output to error correction decoding section 1053 is subjected to error correction decoding at the coding rate assigned to multi-antenna communication apparatus 100 in base station apparatus 200, and separated into received data and radio resource information by demultiplexing section 1054. Then, the radio resource information is output to demodulation section 1052 and error correction decoding section 1053.

  The singular value processing unit 1056 outputs singular values for each independent path at all sample timings, but the singular value processing unit 1056 obtains, for example, an average value for each independent path, A singular value representing each independent path is calculated.

  Then, the channel capacity calculation unit 1057 calculates the number of singular values greater than or equal to a predetermined threshold as the channel capacity of the cell 200 a and outputs it to the cell selection unit 107. The connection cell signal reception process is thus completed.

  The common pilot signal output to radio quality measurement section 1055 is used for radio quality measurement of cell 200a, which is a connected cell, and radio quality measurement section 1055 generates radio quality information. The generated wireless quality information may be multiplexed with a reception confirmation response or the like and transmitted to the base station apparatus 200 as a reception confirmation response signal 454.

  On the other hand, the common pilot signal 455 transmitted from the base station apparatus 300 of the observation cell 300a is sampled as needed by the RF receivers 101-1 and 101-2, subjected to predetermined radio reception processing, and path search. A path search is performed by the unit 102 and despreading is performed by the despreading units 103-1 and 103-2, whereby a despread signal addressed to the own device (multi-antenna communication apparatus 100) is extracted.

  The despread signal is separated into the signal of the connected cell and the signal of the observation cell by the cell separation unit 104. Here, the signal of the cell 300a which is the observation cell is sent to the channel estimation unit 1061 of the observation cell reception processing unit 106. Is output.

  Then, the channel estimation unit 1061 obtains the channel matrix of the cell 300a, and the timing selection unit 1062 selects a sample timing whose total received power is equal to or greater than a predetermined threshold as shown in FIG. 7 (456).

  The selected sample timing is notified to the path synthesizing unit 1063, and the path synthesizing unit 1063 obtains a channel matrix when the signals of the paths corresponding to the selected sample timing are synthesized. The obtained channel matrix is output to the singular value decomposition processing unit 1064.

  Then, the singular value decomposition processing unit 1064 uses the channel matrix output from the path synthesis unit 1063 to perform singular value decomposition processing according to Expression (2), and obtains a singular value for each independent path for the cell 300a. It is done.

  Then, the channel capacity calculation unit 1065 calculates the number of singular values equal to or greater than a predetermined threshold as the channel capacity of the cell 300a that is an observation cell (457). The calculated channel capacity of the cell 300a is output to the cell selection unit 107, and the cell 200a and the cell 300a having the larger channel capacity is selected as a connection cell in the next time unit (458) and corresponds to the connection cell. The base station device becomes the selected base station device. Then, the cell selection unit 107 outputs cell selection information related to the cell selected as the connected cell to the multiplexing unit 108. Here, description will be continued assuming that cell 300a, which was an observation cell, is selected as a connected cell, and base station apparatus 300 has become the selected base station apparatus.

  When the cell selection information is input to the multiplexing unit 108, the multiplexing unit 108 multiplexes the transmission data and the cell selection information to generate multiplexed data. The multiplexed data is error correction encoded by the error correction encoding unit 109 and modulated by the modulation unit 110 to obtain modulated data.

  The modulated data is spread by spreading sections 111-1 and 111-2, subjected to predetermined radio transmission processing by RF transmitting sections 112-1 and 112-2, and a spread signal 459 including transmission data and cell selection information is received by an antenna. Sent through. In FIG. 6B, no signal is transmitted to the base station apparatus 200 that has not been selected, but cell selection information may be transmitted to the base station apparatus 200.

  The spread signal 459 transmitted from the multi-antenna communication apparatus 100 is received via the antenna by the RF receiving units 201-1 and 201-2 of the base station apparatus 300. The received signal is subjected to predetermined radio reception processing by the RF receiving units 201-1 and 201-2, path search is performed by the path search unit 202, and despreading by the despreading units 203-1 and 203-2. As a result, a despread signal addressed to the own device (base station device 300) is extracted.

  The despread signal is demodulated by the demodulator 204, subjected to error correction decoding by the error correction decoding unit 205, and separated into transmission data and cell selection information by the separation unit 206. When cell selection information is output to resource allocation section 207, resource allocation section 207 determines that the own apparatus (base station apparatus 300) has become the selected base station apparatus of multi-antenna communication apparatus 100, and performs multi-antenna communication. Radio resources such as a modulation scheme and a coding rate assigned to transmission data addressed to apparatus 100 are determined (460). The determined radio resource information is output to the transmission control unit 208, and transmission processing of a signal addressed to the multi-antenna communication apparatus 100 is started (461).

  That is, the transmission control unit 208 outputs transmission data addressed to the multi-antenna communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to the multi-antenna communication apparatus 100 to the multiplexing unit 209.

  Then, the multiplexing unit 209 multiplexes the transmission data addressed to the multi-antenna communication apparatus 100 and the radio resource information, and generates multiplexed data. Then, the multiplexed data is subjected to error correction coding by the error correction coding unit 210 and modulated by the modulation unit 211 to obtain modulated data.

  The modulated data is spread by spreading sections 212-1 and 212-2, subjected to predetermined radio transmission processing by RF transmission sections 213-1 and 213-2, and individual data signal 462 including transmission data and radio resource information is generated. Sent via antenna.

  Thus, the signal transmitted from the base station apparatus 300 which is the selected base station apparatus is received by the multi-antenna communication apparatus 100 and received by the connected cell reception processing unit 105 to obtain received data.

  As described above, according to the present embodiment, among the sample timings of the common pilot signal transmitted from the base station apparatus that is not the communication counterpart, the sample timing is specific for the sample timing whose total received power is equal to or greater than a predetermined threshold. A value decomposition process is performed, and the number of singular values equal to or greater than a predetermined threshold is defined as a channel capacity. For this reason, an increase in processing load due to singular value decomposition processing for high-speed cell selection can be suppressed to a minimum, and high-speed cell selection is performed while preventing an increase in circuit scale, thereby reliably improving throughput. Cell coverage can be expanded.

(Embodiment 2)
The feature of Embodiment 2 of the present invention is that a sample timing with the maximum received power is selected from the sampling interval of the received signal, and the singular value decomposition process is performed only for the selected sample timing.

  The configuration of the mobile communication system according to the present embodiment is the same as that of the mobile communication system shown in FIG. Moreover, since the principal part structure of the multi-antenna communication apparatus 100 and the base station apparatus 200 which concerns on this Embodiment is the same as that of the principal part structure of the multi-antenna communication apparatus 100 and the base station apparatus 200 shown in FIG.2 and FIG.5, The description is omitted.

  In the present embodiment, only the internal configuration of the observation cell reception processing unit 106 of the multi-antenna communication apparatus 100 is different from the first embodiment. Therefore, the internal configuration of the observation cell reception processing unit 106 will be described.

  FIG. 8 is a block diagram showing an internal configuration of observation cell reception processing section 106 according to the present embodiment. In this figure, the same parts as those in FIG. The observation cell reception processing unit 106 illustrated in FIG. 8 employs a configuration having a power maximum timing selection unit 5001 instead of the timing selection unit 1062 and the path synthesis unit 1063 of FIG.

  Based on the channel estimation result obtained by the channel estimation unit 1061, the maximum power timing selection unit 5001 obtains the sample timing at each antenna pair of the antenna of the multi-antenna communication apparatus 100 (reception side) and the antenna of the base station apparatus (transmission side) of the observation cell. Each received power is calculated, and a sample timing at which the total received power of all the antenna pairs is maximum is selected as a sample timing for singular value decomposition processing.

  Specifically, for example, the base station apparatus of the observation cell has two antennas, transmission antenna # 1 and transmission antenna # 2, and multi-antenna communication apparatus 100 has two antennas, reception antenna # 1 and reception antenna # 2. In the case of having an antenna, the maximum power timing selection unit 5001 obtains the total received power by adding the received power for each sample timing of a pair of each transmitting antenna and receiving antenna as shown in FIG. Then, the power maximum timing selection unit 5001 selects the sample timing R with the maximum total received power.

  In this embodiment, power maximum timing selection section 5001 selects only the sample timing with the maximum total received power as the sample timing for singular value decomposition processing, so that only one sample timing is always selected. There is no need to synthesize signals of paths corresponding to a plurality of sample timings as in the first mode. Therefore, it is possible to further reduce the processing load during the singular value decomposition processing related to the observation cell.

  As described above, according to the present embodiment, singular value decomposition processing is performed for the sample timing with the highest total received power among the sample timings of the common pilot signal transmitted from the base station apparatus that is not the communication partner. And the number of singular values equal to or greater than a predetermined threshold is defined as the channel capacity, and the base station apparatus having the largest channel capacity is defined as the selected base station apparatus. For this reason, an increase in processing load due to singular value decomposition processing for high-speed cell selection can be suppressed to a minimum, and high-speed cell selection is performed while preventing an increase in circuit scale, thereby reliably improving throughput. Cell coverage can be expanded. In addition, since the sample timing selected is always one, the processing load in the singular value decomposition process can be further reduced.

(Embodiment 3)
A feature of Embodiment 3 of the present invention is that a determinant is used as a channel capacity used for cell selection, and a base station apparatus to be a communication partner is selected depending on the size of the determinant.

  The configuration of the mobile communication system according to the present embodiment is the same as that of the mobile communication system shown in FIG. Moreover, since the principal part structure of the multi-antenna communication apparatus 100 and the base station apparatus 200 which concerns on this Embodiment is the same as that of the principal part structure of the multi-antenna communication apparatus 100 and the base station apparatus 200 shown in FIG.2 and FIG.5, The description is omitted.

  In the present embodiment, only the internal configurations of connected cell reception processing section 105 and observation cell reception processing section 106 of multi-antenna communication apparatus 100 are different from those in the first embodiment. Therefore, the internal configurations of the connected cell reception processing unit 105 and the observation cell reception processing unit 106 will be described.

  FIG. 10 is a block diagram showing an internal configuration of connected cell reception processing section 105 according to the present embodiment. In this figure, the same parts as those in FIG. Connected cell reception processing section 105 shown in FIG. 10 employs a configuration having determinant calculating section 6001 and determinant processing section 6002 instead of singular value processing section 1056 and channel capacity calculating section 1057 of FIG.

The determinant calculation unit 6001 calculates a determinant for each independent path in the connected cell for all sample timings using the channel matrix A _i at the sample timing i of the connected cell. Specifically, the determinant calculation unit 6001 calculates a determinant C _i that is an index of reception quality for each independent path of the connected cell by the following expression (3).

上式（３）において、det（）は行列式を示し、Ｉ_ＭRはＭ_R×Ｍ_Rのサイズの単位行列を示している。上式（３）によって求められる行列式Ｃ_iは、サンプルタイミングごとに求められるスカラー量であり、ＭＩＭＯ通信における独立したパスの受信品質の総和を示す数値である。したがって、セル内に受信品質が高い独立したパスが多ければ多いほど行列式Ｃ_iは大きくなり、行列式Ｃ_iが大きいセルほど、スループットが高いことになる。

In the above equation (3), det () represents a determinant, and I _MR represents a unit matrix having a size of M _R × M _R. The determinant C _i obtained by the above equation (3) is a scalar quantity obtained for each sample timing, and is a numerical value indicating the sum of reception qualities of independent paths in MIMO communication. Therefore, the determinant C _i The more path reception quality is high independent of the cell is increased, as the determinant C _i is large cells, so that the throughput is high.

The determinant processing unit 6002 processes the determinant C _i obtained for each sample timing, calculates a determinant representing the connected cell, and sets it as the channel capacity of the connected cell. That is, the determinant processing unit 6002 obtains an average value by dividing the sum of all determinants C _{1 to} C _N obtained for N sample timings 1 to _N by the total number N of sample timings, for example. A determinant C representing the connected cell is calculated. As described above, if the calculated determinant C is large, the reception quality of the independent path of the connected cell is high and suitable for MIMO communication. Therefore, the determinant processing unit 6002 converts the determinant C into the connected cell. Is output to the cell selector 107 as the channel capacity.

  FIG. 11 is a block diagram showing an internal configuration of observation cell reception processing section 106 according to the present embodiment. In this figure, the same parts as those in FIG. Observation cell reception processing section 106 shown in FIG. 11 has singular value decomposition processing section 1064a and determinant calculation section 6003 instead of singular value decomposition processing section 1064 and channel capacity calculation section 1065 of FIG. A configuration in which a generation unit 6004 is added is adopted.

  The determinant calculation unit 6003 performs the calculation of Equation (3) using the channel matrix output from the path synthesis unit 1063 in the same manner as the connected cell, and observes the determinant relating only to the sample timing selected by the timing selection unit 1062. Calculated as the channel capacity of the cell.

  The singular value decomposition processing unit 1064a compares the channel capacity of the connection cell and the observation cell by the cell selection unit 107, and only when the observation cell is selected as the connection cell in the next time unit, Singular value decomposition processing is performed to calculate a singular value for each independent path only at the sample timing selected by the timing selection unit 1062. That is, the singular value decomposition processing unit 1064a refers to the cell selection information output from the cell selection unit 107 to determine the reception quality for each independent path only when the observation cell is a connected cell. Perform value decomposition.

  When the singular value decomposition processing is performed by the singular value decomposition processing unit 1064a, the spatial multiplexing information generation unit 6004 performs either MIMO communication or STC (Space Time Coding) communication depending on the result of the singular value decomposition processing. To generate spatial multiplexing information indicating whether or not

  Here, in MIMO communication, different data sequences are simultaneously transmitted from a plurality of antennas, whereas in STC communication, the same data sequence is simultaneously transmitted from a plurality of antennas. Therefore, even if the reception quality for each independent path of the connected cell selected by the determinant comparison is relatively low and it is considered that MIMO communication cannot be performed, switching to STC communication reduces the reception quality. And a diversity gain can be obtained.

  In the present embodiment, in calculating the channel capacity of an observation cell used for cell selection, a determinant is calculated that has a processing load that is significantly smaller than that of the singular value decomposition process. And, the singular value decomposition process is performed only when the observation cell is selected as the connection cell in the next time unit, and therefore the singular value decomposition process is always required for calculating the channel capacity of the observation cell. The processing load can be reduced more than 1.

  Next, cell selection by the multi-antenna communication apparatus 100 configured as described above will be described with reference to the sequence diagram shown in FIG. In the present embodiment, an operation in a state where multi-antenna communication apparatus 100 is communicating with base station apparatus 200 as a selected base station apparatus (that is, cell 200a is a connected cell and cell 300a is an observation cell) will be described. . In FIG. 12, the same parts as those in FIG. 6B are denoted by the same reference numerals, and detailed description thereof is omitted. When multi-antenna communication apparatus 100 uses cell 200a as a connected cell, common pilot signal 451 and individual data signal 452 from base station apparatus 200 are predetermined by RF receivers 101-1 and 101-2 of multi-antenna communication apparatus 100. Sampled at the sample timing.

  The received signal obtained by sampling passes through the despreading sections 103-1 and 103-2, and the despread signal addressed to the own apparatus (multi-antenna communication apparatus 100) is extracted.

  The despread signal is separated into the signal of the connection cell and the signal of the observation cell by the cell separation unit 104. Here, the signal of the cell 200a which is the connection cell is output to the connection cell reception processing unit 105, and the connection cell Is received (701).

  That is, the channel estimation unit 1051 obtains a channel matrix for each sample timing, and the demodulation unit 1052 demodulates the received signal using the modulation scheme assigned to the multi-antenna communication apparatus 100 in the base station apparatus 200. The demodulated individual data signal is subjected to error correction decoding by the error correction decoding unit 1053 at the coding rate assigned to the multi-antenna communication apparatus 100 in the base station apparatus 200, and is converted into received data and radio resource information by the separation unit 1054. To be separated.

  In parallel with these processes, the channel matrix obtained by the channel estimation unit 1051 is output to the determinant calculating unit 6001, and the determinant calculating unit 6001 calculates the determinant for each sample timing, and the determinant processing unit In step 6002, a determinant for each sample timing is processed, and for example, a determinant representing a connected cell such as an average value of the determinants for each sample timing is calculated. The calculated determinant is output to the cell selection unit 107 as the channel capacity of the connected cell. The connection cell signal reception process is thus completed.

  The common pilot signal output from demodulation section 1052 to radio quality measurement section 1055 is used for radio quality measurement of cell 200a, which is a connected cell, and radio quality measurement section 1055 generates radio quality information. The generated wireless quality information may be multiplexed with a reception confirmation response or the like and transmitted to the base station apparatus 200 as a reception confirmation response signal 454.

  On the other hand, the common pilot signal 455 transmitted from the base station apparatus 300 of the cell 300a which is an observation cell is sampled at any time by the RF receiving units 101-1 and 101-2, and is sent to the despreading units 103-1 and 103-2. Then, a despread signal addressed to the own device (multi-antenna communication device 100) is extracted.

  The despread signal is separated into the signal of the connected cell and the signal of the observation cell by the cell separation unit 104. Here, the signal of the cell 300a which is the observation cell is sent to the channel estimation unit 1061 of the observation cell reception processing unit 106. Is output.

  Then, as in the first embodiment, the timing selection unit 1062 selects a sample timing whose total received power is equal to or greater than a predetermined threshold (456).

  The selected sample timing is notified to the path synthesizing unit 1063, and the path synthesizing unit 1063 obtains a channel matrix when the signals of the paths corresponding to the selected sample timing are synthesized. The obtained channel matrix is output to determinant calculating section 6003 and singular value decomposition processing section 1064a.

  Then, the determinant calculating unit 6003 performs the calculation of Equation (3) using the channel matrix output from the path combining unit 1063 to obtain the determinant of the cell 300a (702). The obtained determinant is output to the cell selection unit 107 as the channel capacity of the observation cell, and the cell 200a and the cell 300a having the larger channel capacity is selected as the connection cell in the next time unit (458), and the connection cell The base station apparatus corresponding to is the selected base station apparatus. Then, the cell selection unit 107 outputs cell selection information related to the cell selected as the connected cell to the singular value decomposition processing unit 1064a and the multiplexing unit 108. Here, description will be continued assuming that cell 300a, which was an observation cell, is selected as a connected cell, and base station apparatus 300 has become the selected base station apparatus.

  When cell selection information indicating that the cell 300a that was the observation cell has been selected as a connected cell is output to the singular value decomposition processing unit 1064a, the channel matrix output from the path synthesis unit 1063 by the singular value decomposition processing unit 1064a. Is used to perform singular value decomposition processing according to the equation (2) (703). If the cell 200a is selected as the connected cell, the singular value decomposition process is not performed.

  As a result of the singular value decomposition processing, if there are more than a predetermined number of singular values greater than a predetermined threshold, the spatial multiplexing information generation unit 6004 determines that MIMO communication in the cell 300a is possible, and spatial multiplexing indicating that MIMO communication is to be performed. Information is generated. If the singular value larger than the predetermined threshold is less than the predetermined number, the spatial multiplexing information generation unit 6004 determines that it is better to perform STC communication in the cell 300a, and generates spatial multiplexing information indicating that STC communication is performed. Is done. The generated spatial multiplexing information is output to the multiplexing unit 108 via the cell selection unit 107.

  When cell selection information and spatial multiplexing information are input to multiplexing section 108, transmission data, cell selection information, and spatial multiplexing information are multiplexed by multiplexing section 108 to generate multiplexed data. The multiplexed data is transmitted from the error correction coding unit 109 through the RF transmission units 112-1 and 112-2, and a spread signal 704 including transmission data, cell selection information, and spatial multiplexing information is transmitted via an antenna. . In FIG. 12, no signal is transmitted to the base station apparatus 200 that has not been selected, but cell selection information may be transmitted to the base station apparatus 200.

  The spread signal 704 transmitted from the multi-antenna communication apparatus 100 is received via the antenna by the RF receivers 201-1 and 201-2 of the base station apparatus 300. The received signal passes through the despreading sections 203-1 and 203-2, and the despread signal addressed to the own apparatus (base station apparatus 300) is extracted.

  The despread signal is demodulated by demodulator 204, error correction decoded by error correction decoder 205, and separated into transmission data, cell selection information, and spatial multiplexing information by separator 206. When cell selection information and spatial multiplexing information are output to resource allocation section 207, resource allocation section 207 determines that the own apparatus (base station apparatus 300) has become the selected base station apparatus of multi-antenna communication apparatus 100. Then, radio resources such as a modulation scheme and a coding rate assigned to transmission data addressed to multi-antenna communication apparatus 100 are determined (460). In the present embodiment, spatial multiplexing information is referred to when determining radio resources, and it is considered whether MIMO communication or STC communication is performed. The determined radio resource information is output to the transmission control unit 208, and transmission processing of a signal addressed to the multi-antenna communication apparatus 100 is started (705).

  That is, the transmission control unit 208 outputs transmission data addressed to the multi-antenna communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to the multi-antenna communication apparatus 100 to the multiplexing unit 209. Further, transmission control section 208 determines whether to perform MIMO multiplexing or STC communication according to the spatial multiplexing information.

  Then, the multiplexing unit 209 multiplexes the transmission data addressed to the multi-antenna communication apparatus 100 and the radio resource information, and generates multiplexed data. Then, the multiplexed data is subjected to error correction coding by the error correction coding unit 210 and modulated by the modulation unit 211 to obtain modulated data.

  The modulated data is transmitted from the antennas as individual data signals 462 from the spreading sections 212-1 and 212-2 via the RF transmitting sections 213-1 and 213-2. At this time, the individual data signal 462 is transmitted by MIMO communication or STC communication according to the spatial multiplexing information.

  Thus, the signal transmitted from the base station apparatus 300 which is the selected base station apparatus is received by the multi-antenna communication apparatus 100 and received by the connected cell reception processing unit 105 to obtain received data.

  As described above, according to the present embodiment, among the sample timings of the common pilot signal transmitted from the base station apparatus that is not the communication partner, the matrix for the sample timing whose total received power is equal to or greater than a predetermined threshold An equation is obtained, and this determinant is used as the channel capacity, and the base station apparatus having the largest channel capacity is set as the selected base station apparatus. For this reason, an increase in processing load due to singular value decomposition processing for high-speed cell selection can be suppressed to a minimum, and high-speed cell selection is performed while preventing an increase in circuit scale, thereby reliably improving throughput. Cell coverage can be expanded. Also, when selecting a cell, the processing load can be reduced as compared with the case where the singular value decomposition process is always performed.

  In each of the above embodiments, the sample timing used for channel capacity calculation is selected using the total received power of all antenna pairs on the transmission and reception sides, but the total number of antennas on the transmission side or reception side is limited. Received power may be used. That is, for example, the antenna on the transmission side may be fixed to any one, and the sample timing may be selected using the received power only from the antenna. By doing so, the processing load due to cell selection can be further reduced.

  The multi-antenna communication apparatus according to the first aspect of the present invention provides a plurality of antennas at a predetermined sample timing for a signal of a connection cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connection cell. Receiving means for sampling, first calculation means for calculating the channel capacity of the connected cell using the signal of the connected cell, and one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled Comparing the channel capacity of the connected cell and the channel capacity of the observation cell by comparing the channel capacity of the observation cell with the second calculation means for calculating the channel capacity of the observation cell for the selected sample timing Cell selector that selects the cell with the largest as the connected cell in the next time unit And, a configuration with.

  According to this configuration, the channel capacity of the connected cell is calculated, and one or more sample timings are selected from the sample timings of the signal of the observation cell to calculate the channel capacity of the observation cell. Cell, the amount of processing required to calculate the channel capacity of the observation cell can be reduced, high-speed cell selection is performed while preventing an increase in circuit scale, and throughput is reliably improved to ensure cell coverage. Can be enlarged.

  A multi-antenna communication apparatus according to a second aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the timing selection means selects a sample timing having a received power equal to or higher than a predetermined threshold among the plurality of sample timings. Take.

  According to this configuration, since the sample timing at which the received power is equal to or higher than the predetermined threshold is selected, it is possible to select a sample timing at which the received power is absolutely large, not the relative comparison of the received power, and the channel capacity of the observation cell. Can be calculated more accurately.

  The multi-antenna communication apparatus according to a third aspect of the present invention employs a configuration in which, in the first aspect, the timing selection unit selects a sample timing with the maximum received power among the plurality of sample timings.

  According to this configuration, since the sample timing with the maximum received power is selected, the channel matrix used for calculating the channel capacity is accurately obtained, and the channel capacity of the observation cell can be accurately calculated.

  The multi-antenna communication apparatus according to a fourth aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the timing selection means selects a predetermined number of sample timings from among the plurality of sample timings in which reception power is larger. Take the configuration.

  According to this configuration, since a predetermined number of sample timings are selected from the one having higher reception power, the number of sample timings to be subjected to channel capacity calculation is always constant, and even when the reception power is low overall, Timing is definitely selected.

  The multi-antenna communication apparatus according to a fifth aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the timing selecting means selects a sample timing according to received power at any one of the plurality of antennas. Take the configuration.

  According to this configuration, since the sample timing is selected according to the reception power at one antenna, the amount of calculation such as calculation of reception power is reduced, and the processing load necessary for cell selection can be further reduced.

  The multi-antenna communication apparatus according to a sixth aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the first calculation means performs singular value decomposition processing for each of a plurality of sample timings at which the signal of the connected cell is sampled. A singular value decomposition processing unit for obtaining a singular value indicating the reception quality for each independent path in the connected cell for each of the plurality of sample timings for each independent path, and a predetermined value for the obtained singular value. Of the singular value processing unit for obtaining one singular value for each independent path in the connection cell, and a singular value for each independent path in the connection cell obtained by the singular value processing unit. A channel capacity calculation unit that calculates the number of singular values equal to or greater than the threshold value as the channel capacity of the connected cell.

  The multi-antenna communication apparatus according to a seventh aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the second calculation means performs a singular value decomposition process on the selected sample timing, A singular value decomposition processing unit that obtains one singular value for each independent path, and calculates the number of singular values that are equal to or greater than a predetermined threshold among the singular values for each independent path in the observation cell as the channel capacity of the observation cell And a channel capacity calculation unit.

  According to these configurations, there are many independent paths with high reception quality because the singular value for each independent path is obtained from the result of the singular value decomposition processing, and the number of singular values equal to or greater than a predetermined threshold is the cell channel capacity. The channel capacity increases with the cell. For this reason, a cell having a larger channel capacity is more suitable for MIMO communication, and a cell capable of reliably improving throughput can be selected.

  The multi-antenna communication apparatus according to an eighth aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the first calculation means performs calculation for each of a plurality of sample timings at which the signal of the connected cell is sampled. A determinant calculating unit that calculates a determinant indicating the sum of reception qualities for each independent path in the connected cell for each of the plurality of sample timings for each independent path; and a predetermined determinant for the calculated determinant And a determinant processing unit that performs processing and obtains one determinant as the channel capacity of the connected cell for each independent path in the connected cell.

  The multi-antenna communication apparatus according to a ninth aspect of the present invention is the multi-antenna communication apparatus according to the first aspect, wherein the second calculation means performs an operation on the selected sample timing and performs independent paths in the observation cell. A configuration having a determinant calculating unit that calculates one determinant as the channel capacity of the observation cell for each is adopted.

  According to these configurations, since the determinant indicating the sum of the reception qualities for each independent path is used as the channel capacity of the cell, the channel capacity increases as the cell has a larger sum of the reception qualities of the independent paths. Therefore, a cell suitable for MIMO communication can be selected without performing singular value decomposition processing, and the processing load necessary for cell selection can be reduced.

  A multi-antenna communication apparatus according to a tenth aspect of the present invention, in the ninth aspect, when an observation cell in a current time unit is selected as a connection cell in the next time unit by the cell selection means, Singular value decomposition processing means for performing singular value decomposition processing on the sample timing selected by the timing selection means to obtain one singular value for each independent path in the observation cell; and for each independent path in the observation cell If the number of singular values greater than or equal to a predetermined threshold is greater than or equal to a predetermined number, spatial multiplexing information for performing MIMO communication is generated, and the number of singular values greater than or equal to the predetermined threshold is less than the predetermined number. For example, the configuration further includes generating means for generating spatial multiplexing information for performing STC communication.

  According to this configuration, the singular value decomposition process is performed only when the observation cell becomes a connected cell by comparison of the determinants, and based on this result, the spatial multiplexing information indicating whether to perform MIMO communication or STC communication is obtained. Therefore, it is possible to reduce the processing load by performing singular value decomposition processing only when necessary, and to prevent reception quality degradation and obtain diversity gain even when MIMO communication is impossible. .

  A cell selection method according to an eleventh aspect of the present invention is a method of selecting a signal of a connected cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connected cell via a plurality of antennas at a predetermined sample timing. Sampling, calculating the channel capacity of the connected cell using the signal of the connected cell, selecting one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled, Calculating the channel capacity of the observation cell for the selected sample timing, comparing the channel capacity of the connected cell and the channel capacity of the observation cell, and determining the cell with the largest channel capacity in the next time unit. Selecting as a connected cell.

  According to this method, the channel capacity of the connected cell is calculated, and the channel capacity of the observation cell is calculated by selecting one or more sample timings from the sample timing of the signal of the observation cell. Cell, the amount of processing required to calculate the channel capacity of the observation cell can be reduced, high-speed cell selection is performed while preventing an increase in circuit scale, and throughput is reliably improved to ensure cell coverage. Can be enlarged.

  The multi-antenna communication apparatus and cell selection method of the present invention can perform high-speed cell selection while preventing an increase in circuit scale, and can reliably improve throughput and expand cell coverage, for example, near the cell boundary. It is useful as a multi-antenna communication apparatus and a cell selection method for selecting a base station apparatus to be a communication partner with a short period such as a slot when positioned.

The figure which shows the structure of the mobile communication system which concerns on Embodiment 1 of this invention. FIG. 2 is a block diagram showing a main configuration of the multi-antenna communication apparatus according to Embodiment 1. The block diagram which shows the internal structure of the connection cell reception process part which concerns on Embodiment 1. FIG. FIG. 3 is a block diagram showing an internal configuration of an observation cell reception processing unit according to Embodiment 1 FIG. 3 is a block diagram showing a main configuration of the base station apparatus according to Embodiment 1. (A) Sequence diagram showing cell selection operation by multi-antenna communication device at start of communication (b) Sequence diagram showing cell selection operation by multi-antenna communication device during communication The figure which shows the example of the sample timing selection which concerns on Embodiment 1 The block diagram which shows the internal structure of the observation cell reception process part which concerns on Embodiment 2 of this invention. The figure which shows the example of the sample timing selection which concerns on Embodiment 2. The block diagram which shows the internal structure of the connection cell reception process part which concerns on Embodiment 3 of this invention. FIG. 9 is a block diagram showing an internal configuration of an observation cell reception processing unit according to the third embodiment. Sequence diagram showing cell selection operation by multi-antenna communication apparatus during communication (A) A figure showing an example of cell selection operation by FCS (b) A figure showing an example of a measurement result of reception SIR

Explanation of symbols

104 Cell Separation Unit 105 Connected Cell Reception Processing Unit 1051 Channel Estimation Unit 1052 Demodulation Unit 1052a Singular Value Decomposition Processing Unit 1053 Error Correction Decoding Unit 1054 Separation Unit 1055 Radio Quality Measurement Unit 1056 Singular Value Processing Unit 1057 Channel Capacity Calculation Unit 6001 Determinant Calculation Unit 6002 determinant processing unit 106 observation cell reception processing unit 1061 channel estimation unit 1062 timing selection unit 1063 path synthesis unit 1064, 1064a singular value decomposition processing unit 1065 channel capacity calculation unit 5001 maximum power timing selection unit 6003 determinant calculation unit 6004 space Multiplex information generator 107 Cell selector

Claims (11)

Receiving means for sampling a signal of a connection cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connection cell via a plurality of antennas at a predetermined sample timing;
First calculating means for calculating a channel capacity of the connected cell using a signal of the connected cell;
Timing selection means for selecting one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled;
Second calculation means for calculating the channel capacity of the observation cell for the selected sample timing;
Cell selection means for comparing the channel capacity of the connection cell and the channel capacity of the observation cell, and selecting a cell having the largest channel capacity as a connection cell in the next time unit;
A multi-antenna communication apparatus comprising: The timing selection means includes
The multi-antenna communication apparatus according to claim 1, wherein among the plurality of sample timings, a sample timing whose received power is equal to or greater than a predetermined threshold is selected. The timing selection means includes
The multi-antenna communication apparatus according to claim 1, wherein a sample timing with the maximum received power is selected from the plurality of sample timings. The timing selection means includes
2. The multi-antenna communication apparatus according to claim 1, wherein a predetermined number of sample timings are selected from the plurality of sample timings in descending order of reception power. The timing selection means includes
The multi-antenna communication apparatus according to claim 1, wherein a sample timing is selected according to received power at any one of the plurality of antennas. The first calculation means includes
Singular value decomposition processing is performed for each of a plurality of sample timings at which the signal of the connected cell is sampled, and a singular value indicating reception quality for each independent path in the connected cell is determined for each of the plurality of independent paths. A singular value decomposition processing unit for determining the number of sample timings;
A singular value processing unit that performs predetermined processing on the obtained singular value and obtains one singular value for each independent path in the connection cell;
Of the singular values for each independent path in the connection cell obtained by the singular value processing unit, a channel capacity calculation unit that calculates the number of singular values equal to or greater than a predetermined threshold as the channel capacity of the connection cell;
The multi-antenna communication apparatus according to claim 1, further comprising: The second calculation means includes
A singular value decomposition processing unit that performs singular value decomposition processing on the selected sample timing and obtains one singular value for each independent path in the observation cell;
Of the singular values for each independent path in the observation cell, a channel capacity calculation unit that calculates the number of singular values equal to or greater than a predetermined threshold as the channel capacity of the observation cell;
The multi-antenna communication apparatus according to claim 1, further comprising: The first calculation means includes
An arithmetic operation is performed for each of a plurality of sample timings at which the signal of the connected cell is sampled, and a determinant indicating a sum of reception qualities for each independent path in the connected cell is obtained for each of the plurality of samples. A determinant calculating unit for calculating the number of timings;
A determinant processing unit that performs predetermined processing on the calculated determinant and obtains one determinant as a channel capacity of the connected cell for each independent path in the connected cell;
The multi-antenna communication apparatus according to claim 1, further comprising: The second calculation means includes
A determinant calculating unit that performs an operation on the selected sample timing and calculates one determinant as a channel capacity of the observation cell for each independent path in the observation cell;
The multi-antenna communication apparatus according to claim 1, further comprising: When the observation cell in the current time unit is selected as the connected cell in the next time unit by the cell selection unit, the singular value decomposition process is performed on the sample timing selected by the timing selection unit, and the observation is performed. Singular value decomposition processing means for obtaining one singular value for each independent path in the cell;
Among the singular values for each independent path in the observation cell, if the number of singular values equal to or greater than a predetermined threshold is equal to or greater than the predetermined number, spatial multiplexing information is generated to perform MIMO communication, and the singular value equal to or greater than the predetermined threshold Generating means for generating spatial multiplexing information indicating that STC communication is performed if the number is less than a predetermined number;
The multi-antenna communication apparatus according to claim 9, further comprising: Sampling a signal of a connection cell covered by a communication partner in a current time unit and a signal of an observation cell adjacent to the connection cell via a plurality of antennas at a predetermined sample timing;
Calculating the channel capacity of the connected cell using the signal of the connected cell;
Selecting one or more sample timings from a plurality of sample timings at which the signal of the observation cell is sampled;
Calculating the channel capacity of the observation cell for the selected sample timing;
Comparing the channel capacity of the connected cell and the channel capacity of the observation cell and selecting the cell with the largest channel capacity as the connected cell in the next time unit;
A cell selection method characterized by comprising:

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