JP2006135881A - Multi-carrier communication device and cell selection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute high-speed cell selection while preventing an increase in a circuit scale when combining an MIMO communication with a multi-carrier communication, to reliably improve throughput, and to expand cell coverage. <P>SOLUTION: A cell separation part 104 divides signals of each sub carrier into signals of a connection cell and signals of an observation cell. A connection cell reception processing part 105 performs singular value decomposition processing in a process of reception processing to the signals of the connection cell, and calculates a channel capacity of the connection cell. An observation cell reception processing part 106 performs reception processing to the signals of the observation cell, and calculates a channel capacity of the observation cell. Regarding the observation cell, only the channel capacity of the sub carrier whose total reception power is large is calculated. A cell selection part 107 performs magnitude comparison of the channel capacity of the connection cell and the channel capacity of the observation cell, and make a base station device of the cell whose channel amount is larger a base station device of a communications partner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multicarrier communication apparatus and a cell selection method, and more particularly, to a multicarrier that selects a cell of a base station apparatus that is a communication partner in a system to which MIMO (Multi Input Multi Output) communication is applied in a short cycle such as a slot. The present invention relates to a carrier communication apparatus and a cell selection method.

  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. 11A 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 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, as a technique for improving throughput, MIMO communication in which different data sequences are simultaneously transmitted from a plurality of antennas has been actively studied. In particular, by combining multi-carrier communication such as multi-carrier CDMA (Code Division Multiple Access) communication using a plurality of carriers having different frequencies (hereinafter referred to as “subcarriers”) and MIMO communication Further, it is expected to further improve the throughput (for example, see 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) “Configuration of QR replica-MLD with symbol replica candidate reduction using pilot channel estimation and ranking in OFCDM MIMO multiplexing”, NTT DoCoMo, RCS 2003-312, March 2004

  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, when MIMO communication and multicarrier communication are combined, a plurality of subcarriers are included in the received signal, so that demodulation processing for performing high-speed cell selection becomes complicated and circuit scale increases. There's a problem.

  The present invention has been made in view of such a point, and when combining MIMO communication and multicarrier communication, high-speed cell selection is performed while preventing an increase in circuit scale, and the throughput is reliably improved and the cell is improved. An object of the present invention is to provide a multicarrier communication apparatus and a cell selection method capable of expanding the coverage.

  The multicarrier communication apparatus according to the present invention comprises: a receiving means for receiving 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 from a plurality of antennas; First calculation means for calculating a channel capacity of the connected cell using a signal; subcarrier selection means for selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell; The second calculation means for calculating the channel capacity of the observation cell for a carrier, the channel capacity of the connection cell and the channel capacity of the observation cell are compared, and the cell with the largest channel capacity is connected in the next time unit And a cell selection means for selecting as the above.

  The cell selection method according to the present invention includes a step of receiving 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 from a plurality of antennas, and a signal of the connection cell. Using the step of calculating the channel capacity of the connected cell, the step of selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell, and the step of selecting the observation cell for the selected subcarrier A step of calculating a channel capacity and a step of 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. .

  According to these, the channel capacity of the connected cell is calculated, one or more subcarriers constituting the signal of the observation cell are selected, the channel capacity of the observation cell is calculated, and the cell with the largest channel capacity is selected. Because it is the next connected cell, the amount of processing required to calculate the channel capacity of the observation cell can be reduced, and when MIMO communication and multicarrier communication are combined, a high-speed cell is prevented while preventing an increase in circuit scale. Selection can be performed to reliably improve throughput and expand cell coverage.

  According to the present invention, when MIMO communication and multi-carrier communication are combined, high-speed cell selection can be executed while preventing an increase in circuit scale, and throughput can be reliably improved and cell coverage can be expanded.

  The gist of the present invention is to select a subcarrier having a large reception power from all subcarriers constituting a multicarrier signal, and to use a base of a cell having many independent paths that can be used for MIMO communication using only the selected subcarrier. It is to select a station device.

  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, multicarrier communication apparatus 100 located in a region near the boundary between cell 200a covered by base station apparatus 200 and cell 300a covered by base station apparatus 300 includes base station apparatus 200 and base station apparatus. A common pilot channel signal (common pilot signal) transmitted from both sides 300 is received. In addition, the multicarrier 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 multicarrier communication apparatus 100 according to the present embodiment. The multicarrier communication apparatus 100 shown in FIG. 2 includes RF (Radio Frequency) receiving units 101-1 and 101-2, GI (Guard Interval) removing units 102-1 and 102-2, and FFT (Fast (Fourier Transform) sections 103-1, 103-2, cell separation section 104, connected cell reception processing section 105, observation cell reception processing section 106, cell selection section 107, multiplexing section 108, error correction coding section 109 Modulation unit 110, IFFT (Inverse Fast Fourier Transform) units 111-1, 111-2, GI insertion units 112-1, 112-2, and RF transmission units 113-1, 113-2. is doing. In this embodiment, multicarrier communication apparatus 100 is configured to have two antennas. However, when there are three or more antennas, each processing unit from the RF receiving unit to the FFT unit and the IFFT unit Each processing unit up to the RF transmission unit is provided corresponding to the antenna.

  The RF receiving units 101-1 and 101-2 receive signals from the corresponding antennas, respectively, and perform predetermined wireless reception processing (down-conversion, A / D conversion, etc.) on the received signals. Note that the received signal in this embodiment is a multicarrier signal in which a signal is superimposed on a plurality of subcarriers having different frequencies.

  GI removal sections 102-1 and 102-2 remove guard intervals inserted to prevent intersymbol interference between symbols of the received signal.

  FFT sections 103-1 and 103-2 perform fast Fourier transform on the received signal after removal of the guard interval, and extract signals superimposed on a plurality of subcarriers.

  Cell separation section 104 separates each subcarrier signal into a signal for each cell. Specifically, cell separation section 104 is adjacent to the connected cell and the signal of the cell of the base station apparatus (hereinafter referred to as “connected cell”) that is currently the communication partner of multicarrier communication apparatus 100. The signal of each subcarrier is separated into a signal of a cell having a boundary with a connected cell in the vicinity of the position of carrier communication apparatus 100 (hereinafter referred to as an “observation cell”). Note that, when there are a plurality of observation cells, the cell separation unit 104 separates the signal of each subcarrier into the signal of each observation cell.

  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 multicarrier 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 subcarriers, but the channel capacity is calculated only for subcarriers with a large total received power. 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.

  Modulation section 110 modulates the encoded data and outputs the obtained modulation data to IFFT sections 111-1 and 111-2.

  IFFT sections 111-1 and 111-2 perform inverse fast Fourier transform on the modulated data, superimpose the modulated data on a plurality of subcarriers, and output the obtained multicarrier signals to GI insertion sections 112-1 and 112-2. To do.

  GI insertion sections 112-1 and 112-2 insert a guard interval between each symbol of the multicarrier signal.

  The RF transmitters 113-1 and 113-2 perform predetermined radio transmission processing (D / A conversion, up-conversion, etc.) on the multicarrier signal after insertion of the guard interval, 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 multicarrier 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 ), the channel As a result of the estimation, a channel matrix having a size of M _R × M _T is obtained for each subcarrier. That is, for subcarrier i, if the transmission signal vector from the base station apparatus is x _i (t) and the noise signal vector in the propagation path is n _i (t), the received 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)
Channel estimation section 1051 obtains channel matrix A _i for each subcarrier satisfying 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 spatial separation and demodulation processing corresponding to the MIMO multiplexing scheme and modulation scheme on the transmission side (base station apparatus 200 or base station apparatus 300), and also performs error correction decoding section 1053 on the demodulated individual data signal. And output to the wireless quality measuring unit 1055. Singular value decomposition processing section 1052a performs singular value decomposition processing using channel matrix A _i in the course of demodulation, and calculates singular values for each independent path in the connected cell for all subcarriers. Specifically, the singular value decomposition processing unit 1052a calculates the singular value for each independent path of the connected cell related to the subcarrier 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 subcarrier 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 singular values λ _{1,1 to} λ _{1 , MR} , λ _{2,1 to} λ _{2, MR} ,... Obtained for N subcarriers 1 to N,. 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 subcarriers 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.

The subcarrier selection unit 1062 determines, for each subcarrier in each antenna pair, the antenna of the multicarrier communication apparatus 100 (reception side) and the antenna of the base station apparatus (transmission side) of the observation cell from the channel estimation result by the channel estimation unit 1061. The received power is calculated, and the subcarrier having the largest total received power of all the antenna pairs is selected as a subcarrier for singular value decomposition processing. That is, subcarrier selecting section 1062 receives, for each subcarrier, the received power of signals from M _T transmitting antennas received by M _R receiving antennas (that is, for one subcarrier). M _R × M _T received power) is added to calculate the total received power for each subcarrier, and the subcarrier having the largest total received power 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, the processing load of the singular value decomposition processing can be reduced by selecting the subcarrier having the largest total received power as described above and performing the singular value decomposition processing only for this subcarrier.

  Further, for the subcarrier having the largest total received power, since the channel matrix is most accurately obtained, it is considered that the result of the singular value decomposition process is also accurate. As a result, the channel capacity of the observation cell can be accurately calculated with a small amount of processing.

  Note that the subcarrier selection unit 1062 does not select only one subcarrier having the largest total received power, but selects a predetermined number of subcarriers from the largest total received power, or the total received power is predetermined. A subcarrier larger than the threshold may be selected. In these cases, the number of subcarriers to be subjected to singular value decomposition processing increases and the processing load becomes larger than the case of targeting only one subcarrier, but the amount of information used for singular value decomposition processing is small. The number of singular values outliers can be eliminated.

  The singular value decomposition processing unit 1063 performs the singular value decomposition processing according to the expression (2) using the channel matrix of the observation cell in the same manner as the connected cell, and only the subcarrier selected by the subcarrier selection unit 1062 in the observation cell. Calculate the singular value for each independent path.

  When only one subcarrier is selected by the subcarrier selecting unit 1062, the singular value decomposition processing unit 1063 directly uses the singular value for each independent path obtained by the singular value decomposition processing to the channel capacity calculation unit 1064. When a plurality of subcarriers are selected, a singular value representing an independent path is calculated and output to the channel capacity calculation unit 1064 in the same manner as the singular value processing unit 1056 of the connected cell reception processing unit 105. To do.

  The channel capacity calculation unit 1064 compares the singular value for each independent path output from the singular value decomposition processing unit 1063 with a predetermined threshold, and calculates the number of singular values equal to or greater than the predetermined threshold 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, GI removing units 202-1 and 202-2, FFT units 203-1 and 203-2, a demodulating unit 204, and an error correction decoding unit. 205, separation section 206, resource allocation section 207, transmission control section 208, multiplexing section 209, error correction coding section 210, modulation section 211, IFFT sections 212-1 and 212-2, GI insertion sections 213-1 and 213- 2 and RF transmitters 214-1 and 214-2. 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.

  GI removal sections 202-1 and 202-2 remove guard intervals inserted between symbols of the received signal.

  FFT sections 203-1 and 203-2 perform fast Fourier transform on the received signal after removal of the guard interval, and extract signals superimposed on a plurality of subcarriers.

  Demodulation section 204 demodulates each subcarrier 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. Radio resources to be allocated to transmission data addressed to the multicarrier communication apparatus 100 are determined.

  The transmission control unit 208 controls the transmission order of transmission data for the multicarrier communication apparatus 100 and other multicarrier communication apparatuses, and generates radio resource allocation information indicating the modulation scheme and 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 IFFT sections 212-1 and 212-2.

  IFFT sections 212-1 and 212-2 perform inverse fast Fourier transform on the modulated data, superimpose the modulated data on a plurality of subcarriers, and output the obtained multicarrier signals to GI insertion sections 213-1 and 213-2. To do.

  The GI insertion units 213-1 and 213-2 insert guard intervals between the symbols of the multicarrier signal.

  The RF transmitters 214-1 and 214-2 perform predetermined radio transmission processing (D / A conversion, up-conversion, etc.) on the multicarrier signal after insertion of the guard interval, and transmit from each corresponding antenna.

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

  First, operations at the start of communication such as when the multicarrier communication apparatus 100 is turned on will be described with reference to FIG. When the multicarrier 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 receivers 101-1 and 101-2 of the multicarrier communication apparatus 100 have base stations Common pilot signal 401 and dedicated data signal 402 from apparatus 200 and common pilot signal 403 and dedicated data signal 404 from base station apparatus 300 are received.

  The received signal is subjected to predetermined radio reception processing by the RF receiving units 101-1 and 101-2, the guard interval is removed by the GI removing units 102-1 and 102-2, and the FFT units 103-1 and 103-2. Is subjected to fast Fourier transform to extract a signal superimposed on a plurality of subcarriers.

  The signal of each subcarrier 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 the start of communication, and both the cell 200a and the cell 300a It is an observation cell. 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 subcarrier selection unit 1062 selects the subcarrier having the largest total received power in each cell (405). .

  Specifically, for example, base station apparatus 200 has two antennas, transmission antenna # 1 and transmission antenna # 2, and multicarrier communication apparatus 100 has two antennas, reception antenna # 1 and reception antenna # 2. If so, the subcarrier selection unit 1062 adds the received power for each subcarrier of each transmission antenna and reception antenna pair, as shown in FIG. 7, and obtains the total received power. Then, subcarrier P having the largest total received power is selected by subcarrier selecting section 1062. Similarly, subcarrier selecting section 1062 selects the subcarrier having the largest total received power for cell 300a of base station apparatus 300.

  The subcarriers selected for each cell are notified to the singular value decomposition processing unit 1063, and the singular value decomposition processing unit 1063 uses the channel matrix corresponding to the selected subcarrier to use the singular value according to Equation (2). A decomposition process is performed, and a singular value for each independent path is obtained for each of the cells 200a and 300a.

  As described above, by selecting and limiting the subcarriers 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, and an increase in circuit scale is prevented. Fast cell selection can be performed. In addition, when selecting a subcarrier, a singular value decomposition process using an accurate channel matrix can be performed by selecting a subcarrier having the largest total received power, and the obtained singular value is also accurate. .

  Then, the channel capacity calculation unit 1064 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, since the singular value decomposition processing is performed for the subcarrier having the largest total received power as described above, the obtained singular value is accurate, and as a result, the channel capacity is reduced. Reliability 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 modulation data is subjected to inverse fast Fourier transform by IFFT units 111-1 and 111-2, so that it is superimposed on a plurality of subcarriers, guard intervals are inserted by GI insertion units 112-1 and 112-2, and RF transmission is performed. Units 113-1 and 113-2 perform predetermined wireless transmission processing, and multicarrier signal 408 including transmission data and cell selection information is transmitted via the antenna. In FIG. 6A, transmission to the base station apparatus 300 that has not been selected is omitted, but cell selection information may also be transmitted to the base station apparatus 300.

  The multicarrier signal 408 transmitted from the multicarrier communication apparatus 100 is received by the RF receivers 201-1 and 201-2 of the base station apparatus 200 via the antenna. The received signals are subjected to predetermined radio reception processing by the RF receiving units 201-1 and 201-2, the guard intervals are removed by the GI removing units 202-1 and 202-2, and the FFT units 203-1, 203. The signal superimposed on a plurality of subcarriers is extracted by performing Fast Fourier Transform with -2.

  The signal of each subcarrier is demodulated by demodulator 204, error correction decoded by error correction decoder 205, and separated into transmission data and cell selection information by separator 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 multicarrier communication apparatus 100, and performs multicarrier 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 transmission control section 208, and transmission processing of a signal addressed to multicarrier communication apparatus 100 is started (410).

  That is, transmission data addressed to multicarrier communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to multicarrier communication apparatus 100 are output to multiplexing section 209 by transmission control section 208.

  Then, the multiplexing unit 209 multiplexes the transmission data addressed to the multicarrier 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 modulation data is subjected to inverse fast Fourier transform by IFFT sections 212-1 and 212-2, so that it is superimposed on a plurality of subcarriers, guard intervals are inserted by GI insertion sections 213-1 and 213-2, and RF transmission is performed. Predetermined radio transmission processing is performed by the units 214-1 and 214-2, and an individual data signal 411 including transmission data and radio resource information is transmitted via the antenna.

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

  Next, with reference to FIG. 6B, the multicarrier communication apparatus 100 communicates with the base station apparatus 200 as a selected base station apparatus (that is, the cell 200a is a connected cell and the cell 300a is an observation cell). I will explain. When multicarrier communication apparatus 100 uses cell 200a as a connected cell, RF receivers 101-1 and 101-2 of multicarrier communication apparatus 100 receive common pilot signal 451 and individual data signal 452 from base station apparatus 200. Is done.

  The received signal is subjected to predetermined radio reception processing by the RF receiving units 101-1 and 101-2, the guard interval is removed by the GI removing units 102-1 and 102-2, and the FFT units 103-1 and 103-2. Is subjected to fast Fourier transform to extract a signal superimposed on a plurality of subcarriers.

  The signal of each subcarrier is separated into the signal of the connection cell and the signal of the observation cell by the cell separation unit 104, but here, the signal of the cell 200a which is the connection cell is output to the connection cell reception processing unit 105, Reception processing of the signal of the connected cell is performed (453).

  That is, the channel estimation unit 1051 obtains a channel matrix for each subcarrier of the cell 200a, and the demodulation unit 1052 receives received signals using the MIMO multiplexing scheme and modulation scheme assigned to the multicarrier communication apparatus 100 in the base station apparatus 200. Demodulated, and singular value decomposition processing is performed by the singular value decomposition processing unit 1052a during the demodulation process. The singular value for each independent path in the connected cell obtained by the singular value decomposition processing 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 multicarrier 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.

  Further, the singular value processing unit 1056 outputs singular values for each independent path with respect to all subcarriers, but the singular value processing unit 1056 obtains an average value for each independent path, for example, 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 cell 300a, which is an observation cell, is received at any time by the RF receivers 101-1 and 101-2, subjected to predetermined radio reception processing, and GI removal. The guard interval is removed by the units 102-1 and 102-2, and fast Fourier transform is performed by the FFT units 103-1 and 103-2, so that signals superimposed on a plurality of subcarriers are extracted.

  The signal of each subcarrier 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 the channel estimation unit of the observation cell reception processing unit 106. It is output to 1061.

  Then, the channel estimation unit 1061 obtains the channel matrix of the cell 300a, and the subcarrier selection unit 1062 selects the subcarrier having the largest total received power in the cell 300a as shown in FIG. 7 (456). .

  The selected subcarrier is notified to the singular value decomposition processing unit 1063, and the singular value decomposition processing unit 1063 uses the channel matrix corresponding to the selected subcarrier to perform the singular value decomposition processing according to Expression (2). In other words, a singular value for each independent path is obtained for the cell 300a.

  Then, the channel capacity calculation unit 1064 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 modulation data is subjected to inverse fast Fourier transform by IFFT units 111-1 and 111-2, so that it is superimposed on a plurality of subcarriers, guard intervals are inserted by GI insertion units 112-1 and 112-2, and RF transmission is performed. Units 113-1 and 113-2 perform predetermined radio transmission processing, and multicarrier signal 459 including transmission data and cell selection information is transmitted via the antenna. 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 multicarrier signal 459 transmitted from the multicarrier 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 signals are subjected to predetermined radio reception processing by the RF receiving units 201-1 and 201-2, the guard intervals are removed by the GI removing units 202-1 and 202-2, and the FFT units 203-1, 203. The signal superimposed on a plurality of subcarriers is extracted by performing Fast Fourier Transform with -2.

  The signal of each subcarrier is demodulated by demodulator 204, error correction decoded by error correction decoder 205, and separated into transmission data and cell selection information by separator 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 multicarrier communication apparatus 100, and multicarrier 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 transmission control section 208, and transmission processing of a signal addressed to multicarrier communication apparatus 100 is started (461).

  That is, transmission data addressed to multicarrier communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to multicarrier communication apparatus 100 are output to multiplexing section 209 by transmission control section 208.

  Then, the multiplexing unit 209 multiplexes the transmission data addressed to the multicarrier 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 modulation data is subjected to inverse fast Fourier transform by IFFT sections 212-1 and 212-2, so that it is superimposed on a plurality of subcarriers, guard intervals are inserted by GI insertion sections 213-1 and 213-2, and RF transmission is performed. Units 214-1 and 214-2 perform predetermined wireless transmission processing, and an individual data signal 462 including transmission data and wireless resource information is transmitted via the antenna.

  Thus, the signal transmitted from the base station apparatus 300 which is the selected base station apparatus is received by the multicarrier 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 subcarriers included in the common pilot signal transmitted from the base station apparatus that is not the communication partner, the singular value is targeted for the subcarrier having the largest total received power. Decomposition processing is performed, and the number of singular values equal to or greater than a predetermined threshold is defined as channel capacity, and the base station apparatus having the largest channel capacity is defined as the selected base station apparatus. Therefore, an increase in processing load due to singular value decomposition processing for high-speed cell selection can be suppressed to a minimum, and when MIMO communication and multicarrier communication are combined, high-speed operation is prevented while preventing an increase in circuit scale. Cell selection can be performed to reliably improve throughput and expand cell coverage.

  In the present embodiment, a multicarrier signal including cell selection information (for example, multicarrier signal 408 in FIG. 6A) is transmitted from multicarrier communication apparatus 100 to a selected base station apparatus. However, the uplink signal is not limited to a multicarrier signal, and may be a CDMA signal, for example.

(Embodiment 2)
A feature of Embodiment 2 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 multicarrier 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 multicarrier communication apparatus 100 and the base station apparatus 200 which are shown in FIG.2 and FIG.5, The description is omitted.

  In the present embodiment, only the internal configurations of connection cell reception processing section 105 and observation cell reception processing section 106 of multicarrier 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. 8 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. 8 employs a configuration having a determinant calculating unit 5001 and a determinant processing unit 5002 instead of the singular value processing unit 1056 and the channel capacity calculating unit 1057 of FIG.

Determinant calculating section 5001 calculates a determinant for each independent path in the connected cell for all subcarriers using channel matrix A _i for subcarrier i of the connected cell. Specifically, the determinant calculating unit 5001 calculates a determinant C _i that serves as an index of the sum of reception qualities 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、サブキャリア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 amount obtained for each subcarrier, 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 5002 processes the determinant C _i obtained for each subcarrier, calculates a determinant representing the connected cell, and sets it as the channel capacity of the connected cell. That is, the determinant processing unit 5002 obtains an average value by dividing the sum of all determinants C _{1 to} C _N obtained for N subcarriers ₁ to _N by the total number N of subcarriers, 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 5002 converts the determinant C into the connected cell. Is output to the cell selector 107 as the channel capacity.

  FIG. 9 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. 9 has singular value decomposition processing section 1063a and determinant calculation section 5003 instead of singular value decomposition processing section 1063 and channel capacity calculation section 1064 in FIG. A configuration in which the generation unit 5004 is added is adopted.

  The determinant calculation unit 5003 performs the calculation of Equation (3) using the channel matrix of the observation cell in the same manner as the connected cell, and obtains the determinant relating only to the subcarrier selected by the subcarrier selection unit 1062 as the channel capacity of the observation cell. Calculate as

  If only one subcarrier is selected by the subcarrier selecting unit 1062, the determinant calculating unit 5003 outputs the calculated determinant as the channel capacity to the cell selecting unit 107 as it is, In the same manner as the determinant processing unit 5002 of the connected cell reception processing unit 105, the determinant representing the connected cell is calculated as the channel capacity and output to the cell selecting unit 107.

  The singular value decomposition processing unit 1063a uses the equation (2) only when the cell capacity of the connection cell and the observation cell is compared by the cell selection unit 107 and the observation cell is selected as the connection cell in the next time unit. Singular value decomposition processing is performed, and singular values for each independent path are calculated only for the subcarriers selected by the subcarrier selection unit 1062. That is, the singular value decomposition processing unit 1063a 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 1063a, the spatial multiplexing information generation unit 5004 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 multicarrier 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 multicarrier 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. . 10, the same parts as those in FIG. 6B are denoted by the same reference numerals, and detailed description thereof is omitted. When multicarrier communication apparatus 100 uses cell 200a as a connected cell, RF receivers 101-1 and 101-2 of multicarrier communication apparatus 100 receive common pilot signal 451 and individual data signal 452 from base station apparatus 200. Is done.

  From the received signal, signals superimposed on a plurality of subcarriers are extracted through GI removal sections 102-1 and 102-2 and FFT sections 103-1 and 103-2.

  The signal of each subcarrier is separated into the signal of the connection cell and the signal of the observation cell by the cell separation unit 104, but here, the signal of the cell 200a which is the connection cell is output to the connection cell reception processing unit 105, Reception processing of the signal of the connected cell is performed (601).

  That is, channel estimation section 1051 obtains a channel matrix for each subcarrier of cell 200a, and demodulation section 1052 demodulates the received signal using the modulation scheme assigned to multicarrier communication apparatus 100 in 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 multicarrier 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 5001, and the determinant calculating unit 5001 calculates the determinant for each subcarrier, and the determinant processing unit In step 5002, a determinant for each subcarrier is processed, and for example, a determinant representing a connected cell such as an average value of the determinant for each subcarrier 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 that is the observation cell is received as needed by the RF receiving units 101-1 and 101-2, and the GI removing units 102-1 and 102-2 and A signal superimposed on a plurality of subcarriers is extracted through FFT sections 103-1 and 103-2.

  The signal of each subcarrier 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 the channel estimation unit of the observation cell reception processing unit 106. It is output to 1061.

  Then, as in the first embodiment, subcarrier selecting section 1062 selects the subcarrier having the largest total received power in cell 300a (456).

  The selected subcarrier is notified to the determinant calculating unit 5003, and the determinant calculating unit 5003 uses the channel matrix corresponding to the selected subcarrier to perform the calculation of Equation (3), and the cell 300a A determinant is determined (602). 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 1063a 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 has been the observation cell has been selected as a connected cell is output to the singular value decomposition processing unit 1063a, the subcarrier selection unit 1062 selects the subcarrier selected by the singular value decomposition processing unit 1063a. The channel matrix corresponding to the carrier is used to perform singular value decomposition processing according to equation (2) (603). 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 5004 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 5004 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 113-1 and 113-2, and a multicarrier signal 604 including transmission data, cell selection information, and spatial multiplexing information is transmitted via the antenna. The In FIG. 10, 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 multicarrier signal 604 transmitted from the multicarrier communication apparatus 100 is received by the RF receivers 201-1 and 201-2 of the base station apparatus 300 via the antenna. Then, the received signal is extracted through the GI removing units 202-1 and 202-2 and the FFT units 203-1 and 203-2, and a signal superimposed on a plurality of subcarriers is extracted.

  The signal of each subcarrier is demodulated by demodulation section 204, error correction decoded by error correction decoding section 205, and separated into transmission data, cell selection information, and spatial multiplexing information by separation section 206. When cell selection information and spatial multiplexing information are output to resource allocation section 207, resource allocation section 207 determines that its own apparatus (base station apparatus 300) has become the selected base station apparatus of multicarrier communication apparatus 100. Then, radio resources such as a modulation scheme and a coding rate allocated to transmission data addressed to multicarrier 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 transmission control section 208, and transmission processing of a signal addressed to multicarrier communication apparatus 100 is started (605).

  That is, transmission data addressed to multicarrier communication apparatus 100 and radio resource information indicating a coding rate and a modulation scheme assigned to multicarrier communication apparatus 100 are output to multiplexing section 209 by transmission control section 208. 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 multicarrier 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 antenna as an individual data signal 462 from the IFFT units 212-1 and 212-2 via the RF transmitting units 214-1 and 214-2. 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 multicarrier 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 subcarriers included in the common pilot signal transmitted from the base station apparatus that is not the communication partner, the determinant for the subcarrier having the largest total received power This determinant is used as the channel capacity, and the base station apparatus with the largest channel capacity is set as the selected base station apparatus. Therefore, an increase in processing load due to singular value decomposition processing for high-speed cell selection can be suppressed to a minimum, and when MIMO communication and multicarrier communication are combined, high-speed operation is prevented while preventing an increase in circuit scale. Cell selection can be performed to reliably improve throughput and expand cell coverage. 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 the present embodiment, a multicarrier signal including cell selection information (that is, multicarrier signal 604 in FIG. 10) is transmitted from multicarrier communication apparatus 100 to a selected base station apparatus. The uplink signal is not limited to a multicarrier signal, and may be a CDMA signal, for example.

  In each of the above embodiments, the subcarriers used for channel capacity calculation are selected using the total received power of all antenna pairs on the transmitting and receiving sides, but the total number of antennas on the transmitting or receiving 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 subcarrier may be selected using the reception power only from the antenna. By doing so, the processing load required for cell selection can be further reduced.

  The multicarrier communication apparatus according to the first aspect of the present invention includes a receiving unit that receives, from a plurality of antennas, 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. First calculating means for calculating the channel capacity of the connected cell using the signal of the connected cell; and subcarrier selecting means for selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell; The second calculation means for calculating the channel capacity of the observation cell for the selected subcarrier is compared with the channel capacity of the connected cell and the channel capacity of the observation cell, and the cell having the largest channel capacity is And a cell selection means for selecting as a connected cell in a time unit.

  According to this configuration, the channel capacity of the connected cell is calculated, one or more subcarriers constituting the signal of the observation cell are selected, the channel capacity of the observation cell is calculated, and the cell having the maximum channel capacity is calculated. To the next connected cell, the amount of processing required to calculate the channel capacity of the observation cell can be reduced, and when MIMO communication and multicarrier communication are combined, high-speed operation is prevented while preventing an increase in circuit scale. Cell selection can be performed to reliably improve throughput and expand cell coverage.

  The multicarrier communication apparatus according to a second aspect of the present invention employs a configuration in which, in the first aspect, the subcarrier selection means selects a subcarrier having the maximum received power among the plurality of subcarriers. .

  According to this configuration, since the subcarrier having 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 multicarrier communication apparatus according to a third aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the subcarrier selection means selects a predetermined number of subcarriers from the plurality of subcarriers having a larger reception power. The structure to do is taken.

  According to this configuration, since a predetermined number of subcarriers are selected from the one with higher reception power, the number of subcarriers for which channel capacity is calculated increases, so the amount of information increases and the abnormal value of channel capacity is reduced. Can be eliminated.

  The multicarrier communication apparatus according to a fourth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the subcarrier selecting means selects a subcarrier having a reception power equal to or higher than a predetermined threshold among the plurality of subcarriers. Take the configuration.

  According to this configuration, since the subcarriers whose received power is equal to or higher than the predetermined threshold are selected, it is possible to select a subcarrier with absolutely large received power instead of relative comparison of received power, and the channel capacity of the observation cell. Can be calculated more accurately.

  The multicarrier communication apparatus according to a fifth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the subcarrier selecting means selects a subcarrier according to received power at any one of the plurality of antennas. The structure to do is taken.

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

  The multicarrier communication apparatus according to a sixth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the first calculation means performs singular value decomposition processing for each of the plurality of subcarriers constituting the signal of the connected cell. A singular value decomposition processing unit for obtaining a singular value indicating reception quality for each independent path in the connected cell for each of the plurality of subcarriers for each independent path, and a predetermined value for the obtained singular value. A singular value processing unit that performs processing and obtains one singular value for each independent path in the connection cell, and a predetermined value among singular values for each independent path in the connection cell obtained by the singular value processing unit. And a channel capacity calculation unit that calculates the number of singular values equal to or greater than a threshold as the channel capacity of the connected cell.

  The multicarrier communication apparatus according to a seventh aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the second calculation means performs a singular value decomposition process on the selected subcarrier, in the observation cell. 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 multicarrier communication apparatus according to an eighth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the first calculation means performs calculation for each of a plurality of subcarriers constituting the signal of the connected cell, A determinant calculating unit that calculates a determinant indicating the total reception quality for each independent path in the connected cell for each of the plurality of subcarriers for each independent path; and predetermined processing for the calculated determinant And a determinant processing unit that obtains one determinant as the channel capacity of the connected cell for each independent path in the connected cell.

  The multicarrier communication apparatus according to a ninth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the second calculation means performs an operation on the selected subcarrier, 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.

  The multicarrier communication apparatus according to the tenth aspect of the present invention is the multicarrier communication apparatus according to the ninth aspect, wherein the cell selection unit selects the observation cell in the current time unit as the connected cell in the next time unit. Singular value decomposition processing means for performing singular value decomposition processing on the subcarriers selected by the subcarrier selection means to obtain one singular value for each independent path in the observation cell; and independent paths 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 If there exists, the structure which has further the production | generation means which produces | generates the spatial multiplexing information to perform STC communication is taken.

  According to this configuration, singular value decomposition processing is performed only when the observation cell becomes a connected cell by comparison of determinants, and based on this result, 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 degradation of reception quality even when MIMO communication is impossible and to obtain diversity gain. .

  The cell selection method according to an eleventh aspect of the present invention includes a step of receiving 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 from a plurality of antennas, Calculating the channel capacity of the connected cell using the signal of the connected cell, selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell, and targeting the selected subcarrier Calculating the channel capacity of the observation cell as follows, comparing the channel capacity of the connection cell and the channel capacity of the observation cell, and selecting the cell with the largest channel capacity as the connection cell in the next time unit; It was made to have.

  According to this method, the channel capacity of the connected cell is calculated, and at least one subcarrier constituting the signal of the observation cell is selected to calculate the channel capacity of the observation cell. To the next connected cell, the amount of processing required to calculate the channel capacity of the observation cell can be reduced, and when MIMO communication and multicarrier communication are combined, high-speed operation is prevented while preventing an increase in circuit scale. Cell selection can be performed to reliably improve throughput and expand cell coverage.

  The multicarrier communication apparatus and the cell selection method of the present invention, when combining MIMO communication and multicarrier communication, perform high-speed cell selection while preventing an increase in circuit scale, and reliably improve throughput to achieve cell coverage. For example, it is useful as a multicarrier communication apparatus and a cell selection method for selecting a cell of a base station apparatus to be a communication partner with a short cycle such as a slot.

The figure which shows the structure of the mobile communication system which concerns on Embodiment 1 of this invention. FIG. 3 is a block diagram showing a main configuration of the multicarrier 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 multicarrier communication apparatus at start of communication (b) Sequence diagram showing cell selection operation by multicarrier communication apparatus during communication The figure which shows the example of the subcarrier selection based on received power The block diagram which shows the internal structure of the connection cell reception process part which concerns on Embodiment 2 of this invention. FIG. 5 is a block diagram showing an internal configuration of an observation cell reception processing unit according to the second embodiment. Sequence diagram showing cell selection operation by multicarrier 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 5001 determinant calculation Unit 5002 determinant processing unit 106 observation cell reception processing unit 1061 channel estimation unit 1062 subcarrier selection unit 1063, 1063a singular value decomposition processing unit 1064 channel capacity calculation unit 5003 determinant calculation unit 5004 spatial multiplexing information generation unit 107 cell selection unit

Claims (11)

Receiving means for receiving, from a plurality of antennas, 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;
First calculating means for calculating a channel capacity of the connected cell using a signal of the connected cell;
Subcarrier selection means for selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell;
Second calculating means for calculating the channel capacity of the observation cell for the selected subcarrier;
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-carrier communication apparatus comprising: The subcarrier selection means includes
The multicarrier communication apparatus according to claim 1, wherein a subcarrier having a maximum reception power is selected from the plurality of subcarriers. The subcarrier selection means includes
The multicarrier communication apparatus according to claim 1, wherein a predetermined number of subcarriers are selected from the plurality of subcarriers in descending order of reception power. The subcarrier selection means includes
The multicarrier communication apparatus according to claim 1, wherein a subcarrier having a reception power equal to or greater than a predetermined threshold is selected from the plurality of subcarriers. The subcarrier selection means includes
The multicarrier communication apparatus according to claim 1, wherein a subcarrier is selected according to reception power at any one of the plurality of antennas. The first calculation means includes
Singular value decomposition processing is performed on each of a plurality of subcarriers constituting the signal of the connected cell, and a singular value indicating reception quality for each independent path in the connected cell is determined for each of the plurality of subcarriers. A singular value decomposition processing unit for determining the number of carriers, and
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 multicarrier communication apparatus according to claim 1, further comprising: The second calculation means includes
A singular value decomposition processing unit that performs a singular value decomposition process on the selected subcarrier 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 multicarrier communication apparatus according to claim 1, further comprising: The first calculation means includes
A determinant indicating the sum of received qualities for each independent path in the connected cell is calculated for each of the plurality of subcarriers constituting the signal of the connected cell, and the plurality of subcarriers for each independent path. A determinant calculating unit that calculates numbers;
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 multicarrier communication apparatus according to claim 1, further comprising: The second calculation means includes
A determinant calculating unit that performs an operation on the selected subcarrier and calculates one determinant as a channel capacity of the observation cell for each independent path in the observation cell;
The multicarrier communication apparatus according to claim 1, further comprising: When an observation cell in the current time unit is selected as a connected cell in the next time unit by the cell selection unit, a singular value decomposition process is performed on the subcarrier selected by the subcarrier selection unit, Singular value decomposition processing means for obtaining one singular value for each independent path in the observation 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 multicarrier communication apparatus according to claim 9, further comprising: Receiving 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 from a plurality of antennas;
Calculating the channel capacity of the connected cell using the signal of the connected cell;
Selecting one or more subcarriers from a plurality of subcarriers constituting the signal of the observation cell;
Calculating the channel capacity of the observation cell for selected subcarriers;
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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