JP2012182515A - Transmitter, program and method of optimizing combination of resource blocks - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter of OFDMA transmission system which can enhance the transmission characteristics by optimizing the combination of resource blocks.SOLUTION: The transmitter further comprises: resource block selection means for outputting a plurality of resource blocks generated from a plurality of subcarriers simultaneously; precoding means for outputting a plurality of transmission streams; MCS determination means for determining a common MCS (Modulation and Coding Scheme) value for all resource blocks of each transmission stream; and difference calculation means for calculating the differential value of the MCS value and the common MCS value of the resource block for each resource block. The resource block selection means outputs a resource block having the maximum differential value and a resource block having the minimum differential value, out of a plurality of differential values, simultaneously as a set, and repeats the processing until all resource blocks are output.

Description

  The present invention relates to a technique for combining resource blocks in a transmitter for an OFDMA (Orthogonal Frequency Division Multiple Access) transmission system.

  In recent years, with the development of wireless communication standards, communication capacity has been increased. In particular, according to IMT-Advanced, the goal is to achieve a transmission rate of 1 Gbps when stationary and several hundred Mbps even when moving. In order to achieve this goal, a frequency bandwidth of about 100 MHz is considered necessary.

  According to LTE (Long Term Evolution) specifications in 3GPP standardization, the downlink (base station-> mobile station) is highly resistant to multipath interference and has a wide frequency band by changing the number of subcarriers. An OFDMA multiplexing transmission system that can handle the width is used. According to this technique, a wideband signal having a high information rate can be transmitted in parallel using a large number of multicarrier signals having a low symbol rate.

  There is a technique of MIMO (Multiple Input Multiple Output) multiplex transmission system that realizes high-speed transmission based on OFDMA. According to this technique, a plurality of transmission streams can be transmitted in parallel at the same frequency and the same time using a plurality of antennas. In addition, frequency diversity gain can be effectively obtained.

  FIG. 1 is an explanatory diagram showing a MIMO multiplexed transmission system in the prior art.

FIG. 1 shows a downlink transmission stream from a base station 1 as a transmitter to a mobile station 2 as a receiver.
(S11) First, the base station 1 transmits a reference signal to the mobile station 2.
(S12) The mobile station 2 measures the channel state with the base station using the reference signal. Then, the mobile station 2 selects an optimal MCS (Modulation and Coding Scheme) value based on the channel state. The “MCS” value is a combination of a modulation scheme and a coding rate that are determined in advance during adaptive modulation. In general, the higher the MCS value, the faster the transmission parameter combination.
(S13) The mobile station feeds back the selected MCS value to the base station as CQI (Channel Quality Indicator) information.

Here, the resource block of FIG. 1 will be described. For example, assume that the base station allocates six resource blocks to a certain mobile station. Here, based on the CQI information received from the mobile station, the MCS values of the six resource blocks are assumed to be “7” “9” “10” “5” “1” “3”. Then, for each resource block, SINR (signal-to-interference-plus-noise ratio) is reproduced using each MCS value. Next, the average SINRave in all resource blocks is calculated from the SINR for each resource block. One common MCS value actually used for communication is selected so that the required error rate in this average SINR _ave can be achieved. Since the common MCS value is selected based on the average SINR _ave , the common MCS value is close to the average value of the MCS values of the resource blocks. According to FIG. 1, the modulation scheme and coding rate are determined for all resource blocks based on the common MCS value = 6.

  As a technique different from the high-speed transmission method described above, there is a spectrum aggregation technique. At present, frequency resources are already tight, and it is very difficult to secure a continuous broadband at once. In order to solve this problem, there is a “spectrum aggregation” technique in which a plurality of carrier signals whose frequency bands are separated from each other are bundled and transmitted simultaneously. According to this technology, a wide frequency band can be secured by simultaneously using a plurality of channel signals having different frequency characteristics.

  As a spectrum aggregation system, there is a technique for allocating channel signals of a plurality of frequency bands having different propagation characteristics according to a user's QoS (Quality Of Service) (see, for example, Patent Document 1). According to this technology, the average QoS, delay (average, maximum delay, jitter, etc.) required for each application, frame error rate, transmission power, maximum transmission rate, minimum guaranteed transmission rate, etc. are considered as the user's QoS. The Each user can be allocated an optimal frequency band according to QoS, and frequency resources can be efficiently operated.

  In addition, there is a technique for preferentially allocating frequency resources to users in order from the highest frequency band among the available frequency bands (see, for example, Patent Document 2). According to this technique, the number of users that can be accommodated in the entire system can be increased.

JP 2006-094001 A WO2006 / 088082

  However, according to any of the conventional techniques, when a plurality of resource blocks are assigned to a certain user in an OFDMA transmission scheme transmitter, there is a possibility that resource blocks with poor radio quality are included. Here, when the number of resource blocks with poor radio quality is large, there is a problem that a low transmission rate is selected in order to suppress deterioration of transmission characteristics, and the amount of data that can be transmitted is reduced.

  According to FIG. 1 described above, an MCS value lower than the initial MCS value based on the measurement of the mobile terminal is selected for RB1 to RB3, and an MCS value higher than the initial MCS value is selected for RB4 to RB6. Will be. In this way, each resource block varies from the common MCS value.

  As the initial MCS value based on the channel state measured by the mobile station is smaller than the common MCS value, the transmission characteristics may be degraded. Particularly, when resource blocks having an initial MCS value smaller than the common MCS value are output in combination, the transmission characteristics may be further deteriorated.

  Therefore, the present invention provides a transmitter, a program, and a method capable of reducing the deterioration of transmission characteristics and improving the transmission rate by optimally combining resource blocks with respect to the transmitter of the OFDMA transmission scheme. Objective.

According to the present invention, subcarrier generation means for dividing a transmission stream into a plurality of subcarriers,
A resource block selecting means for generating a resource block from a plurality of subcarriers and outputting the resource block at the same time;
Precoding means for encoding a plurality of resource blocks and outputting a plurality of transmission streams;
OFDMA (Orthogonal Frequency Division Multiple Access: Orthogonal Frequency Division Multiple Access) which has a plurality of frequency signal processing means for performing frequency signal processing for each transmission stream and outputting to each antenna, and simultaneously transmitting the transmission stream from the plurality of antennas ) Transmitter for transmission system,
MCS determination means for determining a common MCS (Modulation and Coding Scheme) value for all resource blocks for each transmission stream;
Each resource block further includes a difference calculation means for calculating a difference value between the MCS value of the resource block and the common MCS value,
The resource block selection means simultaneously outputs a resource block having the maximum difference value and a resource block having the minimum difference value among a plurality of difference values, and outputs all the resource blocks. It repeats until it does.

According to another embodiment of the transmitter of the present invention, the MCS determining means is
Based on CQI (Channel Quality Indicator) information for each resource block fed back from the mobile station, an MCS value for each resource block is acquired,
Deriving a signal-to-interference ratio based on the MCS value for each resource block, calculating an average signal-to-interference ratio from these signal-to-interference ratios, calculating a common MCS value from the average signal-to-interference ratio, or An average value of all the MCS values of the resource block may be a common MCS value.

According to another embodiment of the transmitter of the present invention,
The transmitter is for spectrum aggregation in which each transmission stream is simultaneously transmitted from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other.
The MCS determination means determines a common MCS value for all resource blocks in the transmission stream for each carrier signal,
The difference calculation means calculates, for each carrier signal, for each resource block in the transmission stream, a difference value between the MCS value of the resource block and the common MCS value,
The resource block selection means derives the minimum difference value for each carrier signal, compares the minimum difference values in both carrier signals, and the resource block of the minimum difference value in one carrier signal that becomes the smaller difference value And the resource block having the maximum difference value in the other carrier signal may be output simultaneously as a set, and this process may be repeated until all resource blocks are output.

According to another embodiment of the transmitter of the present invention,
The transmitter is for spectrum aggregation in which each transmission stream is simultaneously transmitted from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other.
MCS determination means determines a common MCS value for all resource blocks in all transmission streams of all carrier signals,
The difference calculation means calculates, for each carrier signal, for each resource block in the transmission stream, a difference value between the MCS value of the resource block and the common MCS value,
The resource block selection means derives the minimum difference value for each carrier signal, compares the minimum difference values in both carrier signals, and the resource block of the minimum difference value in one carrier signal that becomes the smaller difference value And the resource block having the maximum difference value in the other carrier signal may be output simultaneously as a set, and this process may be repeated until all resource blocks are output.

According to another embodiment of the transmitter of the present invention, the resource block selection means is:
If the smallest difference value is derived for each carrier signal, the smallest difference value in both carrier signals is compared, and if the number is the same,
A maximum difference value is derived for each carrier signal, and a resource block having a maximum difference value in one carrier signal that is a larger difference value and a resource block having a minimum difference value in the other carrier signal are paired. You may output simultaneously and repeat this process until all the resource blocks are output.

According to another embodiment of the transmitter of the present invention,
If the number of resource blocks in both carrier signals is not the same,
The resource block selection means may finally output a group of resource blocks of one carrier signal at the same time.

According to the present invention,
Subcarrier generating means for dividing the transmission stream into a plurality of subcarriers;
A resource block selecting means for generating a resource block from a plurality of subcarriers and outputting the resource block at the same time;
Precoding means for encoding a plurality of resource blocks and outputting a plurality of transmission streams;
A transmission for an OFDMA (Orthogonal Frequency Division Multiple Access) transmission system that has a plurality of frequency signal processing means for performing frequency signal processing for each transmission stream and outputting to each antenna, and simultaneously transmitting the transmission stream from the plurality of antennas A program that allows a computer installed in a machine to function,
MCS determination means for determining a common MCS value for all resource blocks for each transmission stream;
Each resource block further includes a difference calculation means for calculating a difference value between the MCS value of the resource block and the common MCS value,
The resource block selection means simultaneously outputs a resource block having the maximum difference value and a resource block having the minimum difference value among a plurality of difference values, and outputs all the resource blocks. The computer is made to function until it repeats.

According to the present invention,
A first step of dividing each transmission stream into a plurality of subcarriers;
A second step of generating a resource block from a plurality of subcarriers and outputting the plurality of the resource blocks simultaneously,
A third step of encoding a plurality of resource blocks and outputting a plurality of transmission streams;
In a transmitter for an OFDMA (Orthogonal Frequency Division Multiple Access) transmission method, which has a fourth step of performing frequency signal processing for each transmission stream and outputting to each antenna, and simultaneously transmitting the transmission stream from a plurality of antennas A transmission method,
Determine a common MCS value for all resource blocks for each transmission stream;
For each resource block, calculate the difference value between the MCS value of the resource block and the common MCS value,
In the second step, the resource block having the maximum difference value and the resource block having the minimum difference value among a plurality of difference values are output simultaneously as a set, and this process is output to all resource blocks. It repeats until it does.

  According to the transmitter, program, and method of the present invention, transmission characteristics can be improved by optimally combining resource blocks in an OFDMA transmission scheme transmitter. That is, according to the present invention, a resource block with good transmission characteristics can reduce deterioration of transmission characteristics in a resource block with poor transmission characteristics, and improve the overall transmission characteristics.

It is explanatory drawing showing the MIMO multiplexing transmission system in a prior art. It is a function block diagram of the transmitter in this invention. It is explanatory drawing showing the 1st combination method of the resource block in this invention. It is a system configuration | structure figure of a spectrum aggregation. It is explanatory drawing showing the 2nd combination method of the resource block in this invention. It is a graph showing the packet error rate with respect to Eb / NO. It is explanatory drawing showing the 3rd combination method of the resource block in this invention. It is explanatory drawing showing the 4th combination method of the resource block in this invention.

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

  FIG. 2 is a functional configuration diagram of the transmitter according to the present invention.

  According to FIG. 2, the transmitter 1 is applied to an LTE (Long-Term Evolution) -Advanced base station. The transmitter 1 includes a data transmission unit 10, a subcarrier generation unit 11 (111 and 112), a resource block selection unit 12, a pre-coding unit 13, and a frequency signal processing unit 14 (141 and 142). ), An antenna 15, a codebook storage unit 16, a common MCS determination unit 17, and a difference value calculation unit 18. These functional components excluding the antenna 15 can also be realized by executing a program that causes a computer (for example, a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array)) mounted on the transmitter to function.

  The subcarrier generation unit 11 divides the transmission stream into a plurality of subcarriers. According to FIG. 2, the subcarrier generation unit 11 includes an error correction encoder, a symbol mapper, and a serial-to-parallel converter (Serial to Paraveel). The error correction encoder performs error correction encoding processing on the original data, and extracts CRC (Cyclic Redundancy Check) check bits. The symbol mapper adds a check bit to the transmission modulation symbol. The serial / parallel converter converts the data into parallel data for each subcarrier. For example, in the case of an LTE transmitter (the present invention can be applied to LTE-Advanced), 12 subcarriers (subcarrier spacing: 15 kHz, bandwidth: 180 kHz = 12 × 15 kHz) are transmitted on the frequency axis. It is defined as a unit.

  In addition, according to FIG. 1, the subcarrier generation unit 11 is provided for each transmission stream, but one subcarrier generation unit 11 may be shared and used for a plurality of transmission streams. Thereby, the apparatus configuration can be simplified. The feature of the present invention in the transmitter lies in the resource block selection unit 12, the common MCS determination unit 17, and the difference value calculation unit 18.

  The resource block selection unit 12 generates a resource block (RB) from a plurality of subcarriers for each transmission stream. For example, in the case of a transmitter for LTE, 12 subcarriers are collectively handled as one resource block. One slot (7 symbols) of 12 subcarriers is referred to as a “resource block”.

  Then, the resource block selection unit 12 outputs one resource block of each transmission stream to the precoding unit 13 one by one. For example, when three resource blocks are generated for each of the first transmission stream and the second transmission stream, two sets of resource blocks are output to the precoding unit 13 a total of three times.

  The specific operation of the resource block selector 12 will be described in detail with reference to FIG.

  The precoding unit 13 encodes a resource block for each transmission stream with a weighting matrix, and generates a transmission stream for each antenna. The precoding scheme is a technique generally applied to SDM (Space Division Multiplex) transmission processing or STC (Space Time Coding) transmission processing applied to the MIMO multiplexing transmission scheme. The “precoding scheme” is to encode (combine by weighted addition) an input signal sequence and an output signal sequence in accordance with a codebook (pattern code table).

The frequency signal processing unit 14 performs frequency signal processing for each transmission stream and outputs the result to each antenna. According to FIG. 2, the frequency signal processing unit 14 includes an IFFT (Inverse Fast Fourier Transform) unit, a CP (Cyclic Prefix) insertion unit, and a transmission unit. The IFFT unit converts the frequency axis components of the encoded transmission streams s ₁ ′ and s ₂ ′ into time axis components. The CP insertion unit inserts a CP, maintains orthogonality between subcarriers with respect to a delayed wave having a CP time length or less, and improves robustness with respect to a multipath delayed wave. The transmission unit outputs the transmission stream in which the CP is inserted to the antenna.

  The codebook storage unit 16 stores a weighting matrix for the precoding unit 13 in advance.

  The common MCS determination unit 17 determines a common MCS for all resource blocks. For example, the average SINRave of all resource blocks may be calculated from the SINR for each resource block, and the common MCS value may be determined from the average SINRave. Further, simply, an average MCS value of all resource blocks may be determined as a common MCS value from the MCS values for each resource block. The common MCS value is output to the resource block selection unit 12 (in the case of FIG. 1) or the difference value calculation unit 18 (in the case of FIGS. 3, 5, 7, and 8 described later).

  The difference value calculation unit 18 calculates a difference value between the MCS value of the resource block and the common MCS value for each resource block. The difference value for each resource block is output to the resource block selector 12.

  FIG. 3 is an explanatory diagram showing a first combination method of resource blocks in the present invention.

(S31) Based on the CQI information received from the mobile station, the MCS values of the six resource blocks are “7” “9” “10” “5” “1” “3”. Then, SINR based on the MCS value from the mobile station is calculated for each resource block.
(S32) The average SINRave in all resource blocks is calculated from the SINR for each resource block. Then, a common MCS value is determined from the average SINRave. Here, for example, the common MCS value = 6 is set.
(S33) Next, for each resource block, a difference value between the MCS value of the resource block and the common MCS value 6 is calculated. It is assumed that the difference value ΔD _n of the six resource blocks is “1” “3” “4” “−1” “−5” “−3”.

Here, a resource block having a larger difference value ΔD _n means that there is a margin in achieving a predetermined error rate. On the other hand, a resource block having a smaller difference value ΔD _n may not be able to achieve a predetermined error rate and has a high possibility of deterioration in transmission characteristics.

(S34) Next, among the plurality of difference values, the resource block having the smallest difference value (MIN {ΔD _n } = ΔD ₅ = −5: RB5) and the resource block having the largest difference value (MAX {ΔD _n } = ΔD ₃ = 4: RB3).
(S35) Then, resource blocks RB3 and RB5 are selected and output to the precoding unit.

(S36) Next, among the remaining plurality of difference values, the resource block with the smallest difference value (MIN {ΔD _n } = ΔD ₆ = −3: RB6) and the resource block with the largest difference value (MAX { ΔD _An } = ΔD _A2 = 3: RB2) is detected.
(S37) Then, resource blocks RB2 and RB6 are selected and output to the precoding unit.

(S38) Finally, the remaining resource blocks RB1 and RB4 are selected and output to the precoding unit.

  According to the present invention, it is possible to combine resource blocks using only CQI information already fed back in an existing system without receiving special feedback information from a mobile station.

  FIG. 4 is a system configuration diagram of spectrum aggregation.

  According to FIG. 4, the transmitter 1 is transmitting two transmission streams with different carrier signals (800 MHz band, 2 GHz band). On the other hand, the receiver 2 restores while receiving the two streams. Here, the MIMO (Multiple Input Multiple Output) scheme of FIG. 1 is applied to the same frequency band, but according to FIG. 4, it is different frequency bands (different carrier signals). , Trying to send multiple streams. To that end, the first stream transmitted from the first antenna of the transmitter is received only by the first antenna of the receiver. Similarly, the second stream transmitted from the second antenna of the transmitter is received only by the second antenna of the receiver. Therefore, unlike the MIMO multiplexing transmission method, a stream transmitted from one antenna of the transmitter is not received by all the antennas of the receiver. According to the present embodiment, the stream is described as 800 MHz and 2 GHz, but of course, the usable frequency band is not limited to this.

According to Fig.4 (a), the one transmitter (for example, base station) 1 is transmitting the carrier signal of both 800 MHz band and 2 GHz band. The transmitter 1 performs weighted addition encoding processing on the transmission streams s ₁ and s ₂ of the original data, and transmits the transmission streams s ₁ ′ and s ₂ ′ from the antenna for each carrier signal. The transmission streams s ₁ ′ and s ₂ ′ pass through different propagation paths (propagation path characteristics H) for each carrier signal and receive noise (n).
800 MHz band: propagation path characteristic H ₁ , noise component n ₁
2 GHz band: propagation path characteristic H ₂ , noise component n ₂

The receiver ₂ performs maximum likelihood detection and MMSE (Minimum Mean Square Error) equalization on the received stream r ₁ / r ₂ to restore the transmission stream s ₁ / s ₂ of the original data.

According to FIG.4 (b), the 1st base station for 800 MHz bands and the 2nd base station for 2 GHz bands exist separately, respectively. The receiver 2 receives the stream s ₁ from the first base station and receives the stream s ₂ from the second base station. At this time, a transmission stream link function is required between the first base station and the second base station.

  FIG. 5 is an explanatory diagram showing a second combination method of resource blocks in the present invention.

(S51) Six resource blocks are represented, and for each carrier signal (A and B), three resource blocks are assigned to one transmission stream. Then, SINR based on the MCS value from the mobile station is calculated for each resource block.
(S52) For carrier signal A, an average SINR _Aave in all resource blocks is calculated. Then, the common MCS value = 8 is determined from the average SINR _Aave . For carrier signal B, an average SINR _Bave in all resource blocks is calculated. The common MCS value = 3 is determined from the average SINR _Bave .
(S53) Next, for the carrier signal A, the difference values ΔD _A1 = −1, ΔD _A2 = 1, ΔD _A3 = 2 between the MCS value of each resource block and the common MCS value are calculated. For carrier signal B, the difference values ΔD _B4 = 2, ΔD _B5 = −2, ΔD _B6 = 0 between the MCS value of each resource block and the common MCS value are calculated.

(S54) Next, for the carrier signal A, a resource block (MIN {ΔD _An } = ΔD _A1 = −1: RB1) having the smallest difference value among a plurality of difference values is detected. For the carrier signal B, the resource block (MIN {ΔD _Bn } = ΔD _B5 = −2: RB5) having the smallest difference value is detected from among the plurality of difference values. Here, when the difference value (−1) of RB1 and the difference value (−2) of RB5 are compared, the difference value (−2) of RB5 in the carrier signal B is smaller. On the other hand, for the carrier signal A, the resource block (MAX {ΔD _An } = ΔD _A3 = 2: RB3) having the maximum difference value among a plurality of difference values is detected.
(S55) Then, RB3 having the largest difference value in carrier signal A and RB5 having the smallest difference value in carrier signal B are selected and output to the precoding unit.

For carrier signals A and B, MIN {ΔD _An } = MIN {ΔD _Bn } may be obtained. In this case, MAX {ΔD _An }: MAX {ΔD _Bn } is compared so that resource blocks are combined so that transmission characteristics are further improved. For example, when MAX {ΔD _An }> MAX {ΔD _Bn }, the RB of MAX {ΔD _An } and the RB of MIN {ΔD _Bn } are combined. As a result, it can be combined with an RB having good transmission characteristics as much as possible.

(S56) Next, the selection of the remaining resource blocks is determined. For the carrier signal A, the resource block (MIN {ΔD _An } = ΔD _A1 = −1: RB1) having the smallest difference value is detected among the plurality of difference values. For the carrier signal B, the resource block (MIN {ΔD _Bn } = ΔD _B6 = 0: RB6) having the smallest difference value among the plurality of difference values is detected. Here, when the difference value (−1) of RB1 and the difference value (0) of RB6 are compared, the difference value (−1) of RB1 in the carrier signal A is smaller. On the other hand, for the carrier signal B, the resource block (MAX {ΔD _Bn } = ΔD _B4 = 2: RB4) having the maximum difference value is detected among the plurality of difference values.
(S57) Then, RB1 having the smallest difference value in carrier signal A and RB4 having the largest difference value in carrier signal B are selected and output to the precoding unit.

(S58) Finally, for the remaining resource blocks, RB2 of carrier signal A and RB6 of carrier signal B are selected and output to the precoding unit.

  By performing processing in this order by the precoding unit, it is possible to absorb deterioration of transmission characteristics of resource blocks having poor transmission characteristics by resource blocks having good transmission characteristics. As a result, overall transmission characteristics can be improved. In addition, it is also possible to effectively obtain frequency diversity gain by combining resource blocks across frequency bands as much as possible. If the total number of resource blocks is an odd number, one resource block that is not subjected to precoding remains.

  FIG. 6 is a graph showing a packet error rate with respect to Eb / NO.

“Eb / NO” means a power density to noise power density ratio per bit in a digital modulation signal. FIG. 7 shows the packet error rate when the QPSK modulation method is applied and the Eb / NO band is changed with the coding rate as a parameter. According to FIG. 6, each plot is represented as follows.
○: Conventional resource block combination method, coding rate R = 1
Δ: Conventional resource block combination method, coding rate R = 7/8
□: Conventional resource block combination method, coding rate R = 2/3
●: Resource block combination method of the present invention, coding rate R = 1
▲: Resource block combination method of the present invention, coding rate R = 7/8
{Circle around (2)}: Resource block combination method of the present invention, coding rate R = 2/3
Note that the “conventional resource block combination method” is a method in which pre-processing is performed by selecting one resource block at a time starting from the lowest frequency for each frequency band.

  According to FIG. 6, it can be confirmed that the transmission characteristics are improved by applying the present invention regardless of the error correction coding rate. That is, when an attempt is made to achieve a specified error rate under the same Eb / NO environment, a high coding rate can be selected and throughput can be increased by applying the present invention. .

  FIG. 7 is an explanatory diagram showing a third combination method of resource blocks in the present invention.

  According to FIG. 7, in order to simplify the device configuration, the carrier signal A and the carrier signal B can be shared by one error correction encoder. Therefore, for the carrier signals A and B, all resource blocks are unified with a common MCS value. Conversely, according to FIG. 5, a different common MCS value is used for each carrier signal.

(S71) Similar to FIG. 5, six resource blocks are represented for one transmission stream, and each carrier signal is divided into three resource blocks. Then, SINR based on the MCS value from the mobile station is calculated for each resource block.
(S72) For carrier signals A and B, an average SINR _ave in all resource blocks is calculated. Then, the common MCS value = 6 is determined from the average SINR _ave .
(S73) Next, for each resource block in the carrier signals A and B, a difference value between the MCS value of the resource block and the common MCS value is calculated. For the carrier signal A, the difference values ΔD _A1 = 1, ΔD _A2 = 3, ΔD _A3 = 4 are calculated, and for the carrier signal B, the difference values ΔD _B4 = −1, ΔD _B5 = −4, ΔD _B6 = −3. Calculated.

(S74) Next, for the carrier signal A, the resource block (MIN {ΔD _An } = ΔD _A1 = 1: RB1) having the smallest difference value among a plurality of difference values is detected. For the carrier signal B, the resource block (MIN {ΔD _Bn } = ΔD _B5 = −4: RB5) having the smallest difference value among the plurality of difference values is detected. Here, when the difference value (1) of RB1 and the difference value (-4) of RB5 are compared, the difference value (-4) of RB5 in the carrier signal B is smaller. On the other hand, for the carrier signal A, the resource block (MAX {ΔD _An } = ΔD _A3 = 4: RB3) having the maximum difference value among a plurality of difference values is detected.
(S75) Then, RB3 having the maximum difference value in carrier signal A and RB5 having the minimum difference value in carrier signal B are selected and output to the precoding unit.

(S76) Next, the selection of the remaining resource blocks is determined. For the carrier signal A, the resource block (MIN {ΔD _An } = ΔD _A1 = 1: RB1) having the smallest difference value among the plurality of difference values is detected. For the carrier signal B, the resource block (MIN {ΔD _Bn } = ΔD _B6 = −3: RB6) having the smallest difference value among the plurality of difference values is detected. Here, when the difference value (1) of RB1 is compared with the difference value (-3) of RB6, the difference value (-3) of RB6 in the carrier signal B is smaller. On the other hand, for the carrier signal A, the resource block (MAX {ΔD _An } = ΔD _A2 = 3: RB2) having the maximum difference value is detected among the plurality of difference values.
(S77) Then, RB2 having the maximum difference value in carrier signal A and RB6 having the minimum difference value in carrier signal B are selected and output to the precoding unit.

(S78) Finally, for the remaining resource blocks, RB1 of carrier signal A and RB4 of carrier signal B are selected and output to the precoding unit.

  FIG. 8 is an explanatory diagram showing a fourth combination method of resource blocks in the present invention.

  According to FIG. 5 described above, it has been described that the number of resource blocks of the carrier signal A and the number of resource blocks of the carrier signal B are the same. On the other hand, according to FIG. 8, the present invention can be applied even when the number of resource blocks of the carrier signal A and the number of resource blocks of the carrier signal B are different.

(S81) Six resource blocks are represented, four resource blocks are allocated to one transmission stream of carrier signal A, and two resource blocks are allocated to one transmission stream of carrier signal B Is assigned. Then, SINR based on the MCS value from the mobile station is calculated for each resource block.
(S82) For the carrier signal A, the average SINR _Aave in all resource blocks is calculated. Then, the common MCS value = 7 is determined from the average SINR _Aave . For carrier signal B, an average SINR _Bave in all resource blocks is calculated. The common MCS value = 2 is determined from the average SINR _Bave .
(S83) Next, for each carrier signal, a difference value between the MCS value of the resource block and the common MCS value is calculated for each resource block. The difference values ΔD _A1 = 0, ΔD _A2 = 2, ΔD _A3 = 3, ΔD _A4 = −2 are calculated for the carrier signal A, and the difference values ΔD _B5 = −1 and ΔD _B6 = 1 are calculated for the carrier signal B. Is done.

(S84) Next, for the carrier signal A, the resource block (MIN {ΔD _An } = ΔD _A4 = −2: RB4) having the smallest difference value among a plurality of difference values is detected. For the carrier signal B, the resource block (MIN {ΔD _Bn } = ΔD _B5 = −1: RB5) having the smallest difference value among the plurality of difference values is detected. Here, when the difference value (−2) of RB4 is compared with the difference value (−1) of RB5, the difference value (−2) of RB4 in the carrier signal A is smaller. On the other hand, for the carrier signal B, the resource block (MAX {ΔD _Bn } = ΔD _B6 = 1: RB6) having the maximum difference value among a plurality of difference values is detected.
(S85) Then, RB4 having the smallest difference value in carrier signal A and RB6 having the largest difference value in carrier signal B are selected and output to the precoding unit.

(S86) Next, the selection of the remaining resource blocks is determined. For the carrier signal A, the resource block (MIN {ΔD _An } = ΔD _A1 = 0: RB1) having the smallest difference value among the plurality of difference values is detected. Here, when the difference value (0) of RB1 is compared with the difference value (ΔD _B5 = −1) of the remaining RB5, the difference value (−1) of RB5 in the carrier signal B is smaller. On the other hand, for the carrier signal A, the resource block (MAX {ΔD _An } = ΔD _A3 = 3: RB3) having the maximum difference value is detected among the plurality of difference values.
(S87) Then, RB3 having the largest difference value in carrier signal A and RB5 having the smallest difference value in carrier signal B are selected and output to the precoding unit.

(S88) Finally, for the remaining resource blocks, RB1 and RB2 of the carrier signal A are selected and output to the precoding unit. When the number of resource blocks is different for each carrier signal, resource blocks straddling the carrier signal are preferentially combined.

  Another first embodiment common to FIGS. 5, 7 and 8 will be described. According to the resource block selection unit in the above-described embodiment, the minimum difference value is derived for each carrier signal, and the minimum difference values in both carrier signals are different. On the other hand, the minimum difference value in both carrier signals may be the same number. In this case, conversely, the maximum difference value is derived for each carrier signal, and the resource block of the maximum difference value in one carrier signal that becomes the larger difference value and the resource of the minimum difference value in the other carrier signal A block and a set are output simultaneously. This process is repeated until all resource blocks are output. Accordingly, it is possible to reduce degradation of transmission characteristics by combining resource blocks with poor transmission characteristics with resource blocks with good transmission characteristics as much as possible.

Another second embodiment will be described. According to the present invention, even when there are three or more carrier signals (frequency bands), resource blocks can be combined in the same manner. For example, assume the following case.
Frequency band A (number of resource blocks = 4)
Frequency band B (number of resource blocks = 2)
Frequency band C (number of resource blocks = 2)
In this case, when the combination of resource blocks based on FIG. 8 is executed for the frequency band A and the frequency band B, two resource blocks remain in the frequency band A. Thereafter, the resource blocks remaining in the frequency band A and the resource blocks in the frequency band C can be combined by a similar method.

  As described above in detail, according to the transmitter, program, and method of the present invention, transmission characteristics can be improved by optimally combining resource blocks in an OFDMA transmission system transmitter. That is, according to the present invention, a resource block with good transmission characteristics can reduce deterioration of transmission characteristics in a resource block with poor transmission characteristics, and improve the overall transmission characteristics. Moreover, frequency diversity gain can be effectively obtained by performing precoding across carrier signals.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Transmitter, base station 10 Data transmission part 11 Subcarrier generation part 12 Resource block selection part 13 Precoding part 14 Frequency signal processing part 15 Antenna 16 Codebook memory | storage part 17 Common MCS determination part 18 Difference value calculation part 2 Receiver, Mobile station

Claims (8)

Subcarrier generating means for dividing the transmission stream into a plurality of subcarriers;
A resource block selecting means for generating a resource block from a plurality of subcarriers and outputting the resource block at the same time;
Precoding means for encoding a plurality of resource blocks and outputting a plurality of transmission streams;
OFDMA (Orthogonal Frequency Division Multiple Access: orthogonal frequency division multiple) which has a plurality of frequency signal processing means for performing frequency signal processing for each transmission stream and outputting to each antenna, and transmitting the transmission stream simultaneously from the plurality of antennas Connection) transmitter for transmission method,
MCS determination means for determining a common MCS (Modulation and Coding Scheme) value for all resource blocks for each transmission stream;
For each resource block, further comprises difference calculation means for calculating a difference value between the MCS value of the resource block and the common MCS value;
The resource block selection means simultaneously outputs a resource block having the largest difference value and a resource block having the smallest difference value as a set among a plurality of difference values, and this process is performed for all resource blocks. A transmitter characterized by repeating until output. The MCS determination means includes
Based on CQI (Channel Quality Indicator) information for each resource block fed back from the mobile station, an MCS value for each resource block is acquired,
Deriving a signal-to-interference ratio based on the MCS value for each resource block, calculating an average signal-to-interference ratio from the signal-to-interference ratio, and calculating the common MCS value from the average signal-to-interference ratio, or The transmitter according to claim 1, wherein an average value of all the MCS values of all resource blocks is set as the common MCS value. The transmitter is for spectrum aggregation in which each transmission stream is simultaneously transmitted from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
The MCS determining means determines a common MCS value for all resource blocks in the transmission stream for each carrier signal,
The difference calculating means calculates, for each carrier signal, for each resource block in the transmission stream, a difference value between the MCS value of the resource block and the common MCS value;
The resource block selection means derives a minimum difference value for each carrier signal, compares the minimum difference values in both carrier signals, and determines the minimum difference value in one carrier signal that is the smaller difference value. The transmission according to claim 2, wherein the resource block and the resource block having the maximum difference value in the other carrier signal are simultaneously output as a set, and this process is repeated until all resource blocks are output. Machine. The transmitter is for spectrum aggregation in which each transmission stream is simultaneously transmitted from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
The MCS determination means determines a common MCS value for all resource blocks in all transmission streams of all carrier signals,
The difference calculating means calculates, for each carrier signal, for each resource block in the transmission stream, a difference value between the MCS value of the resource block and the common MCS value;
The resource block selection means derives a minimum difference value for each carrier signal, compares the minimum difference values in both carrier signals, and determines the minimum difference value in one carrier signal that is the smaller difference value. The transmission according to claim 2, wherein the resource block and the resource block having the maximum difference value in the other carrier signal are simultaneously output as a set, and this process is repeated until all resource blocks are output. Machine. The resource block selection means includes
Deriving the smallest difference value for each carrier signal, comparing the smallest difference values in both carrier signals, if the number is the same,
A maximum difference value is derived for each carrier signal, and a resource block having a maximum difference value in one carrier signal that has a larger difference value and a resource block having a minimum difference value in the other carrier signal are paired. The transmitter according to claim 3 or 4, wherein the transmitter is output at the same time and this process is repeated until all resource blocks are output. If the number of resource blocks in both carrier signals is not the same,
The transmitter according to claim 3 or 4, wherein the resource block selection means finally outputs a set of resource blocks of one carrier signal at the same time. Subcarrier generating means for dividing the transmission stream into a plurality of subcarriers;
A resource block selecting means for generating a resource block from a plurality of subcarriers and outputting the resource block at the same time;
Precoding means for encoding a plurality of resource blocks and outputting a plurality of transmission streams;
For each transmission stream, a plurality of frequency signal processing means for performing frequency signal processing and outputting to each antenna, and for an OFDMA (orthogonal frequency division multiple access) transmission scheme for transmitting a transmission stream simultaneously from a plurality of antennas A program for causing a computer mounted on a transmitter to function,
MCS determination means for determining a common MCS value for all resource blocks for each transmission stream;
For each resource block, further comprises difference calculation means for calculating a difference value between the MCS value of the resource block and the common MCS value;
The resource block selection means simultaneously outputs a resource block having the largest difference value and a resource block having the smallest difference value as a set among a plurality of difference values, and this process is performed for all resource blocks. A program that causes a computer to function repeatedly until it is output. A first step of dividing each transmission stream into a plurality of subcarriers;
A second step of generating a resource block from a plurality of subcarriers and outputting the plurality of the resource blocks simultaneously,
A third step of encoding a plurality of resource blocks and outputting a plurality of transmission streams;
A transmitter for an OFDMA (Orthogonal Frequency Division Multiple Access) transmission system, which includes a fourth step of performing frequency signal processing for each transmission stream and outputting the result to each antenna, and simultaneously transmitting the transmission stream from a plurality of antennas The transmission method in
Determine a common MCS value for all resource blocks for each transmission stream;
For each resource block, calculate a difference value between the MCS value of the resource block and the common MCS value,
In the second step, the resource block having the maximum difference value and the resource block having the minimum difference value among a plurality of difference values are output simultaneously as a set, and this process is output to all resource blocks. The transmission method characterized by repeating until it does.

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