WO2011052192A1

WO2011052192A1 - Wireless communication terminal device, wireless communication base station device, and sequence number determination method

Info

Publication number: WO2011052192A1
Application number: PCT/JP2010/006330
Authority: WO
Inventors: 岩井敬; 西尾昭彦; 中尾正悟; 小川佳彦; 二木貞樹; 福岡将
Original assignee: パナソニック株式会社
Priority date: 2009-10-27
Filing date: 2010-10-26
Publication date: 2011-05-05

Abstract

Provided is a terminal that can prevent the number of signaling bits from a base station to a terminal from increasing even when applying Walsh sequences to DM-RS in LTE-Advanced. The provided terminal (100) is used in a wireless communication system in which one of a plurality of transmission parameters is set for each of a plurality of terminals, and a base station notifies the plurality of terminals of the set transmission parameters. On the basis of a one-to-one correspondence between the plurality of transmission parameters and Walsh sequence numbers, a determination unit (107) in the terminal determines the Walsh sequence number corresponding to the transmission parameter that was set for that terminal and sent from the base station. A multiplication unit (108) multiples a reference signal sequence by the Walsh sequence determined by the determination unit (107).

Description

Wireless communication terminal apparatus, wireless communication base station apparatus, and sequence number determination method

The present invention relates to a radio communication terminal apparatus, a radio communication base station apparatus, and a sequence number determination method.

MU-MIMO (Multiple User-Multiple Input Multiple 適用 Output) is applied to the uplink of LTE-Advanced, which is an extension of 3GPP LTE and LTE. MIMO is a technique in which a transmitter / receiver is equipped with a plurality of antennas and enables simultaneous spatial multiplexing transmission of different signal sequences at the same frequency. MU-MIMO is a technology for performing MIMO communication between a plurality of wireless communication terminal devices (hereinafter simply referred to as terminals) and a wireless communication base station device (hereinafter simply referred to as a base station). Efficiency can be improved.

In MU-MIMO, it is necessary to orthogonalize a data demodulation reference signal (DM-RS: Demodulation RS) between terminals in order to separate transmission data of each terminal on the base station side. In LTE, DM-RSs between terminals are orthogonalized by varying the amount of cyclic shift (CS) of DM-RS sequences between terminals. However, in order to maintain the orthogonality of DM-RS between terminals by the CS amount, it is necessary to match the DM-RS transmission bandwidth and transmission band position of a plurality of terminals to be MU-MIMO multiplexed, and frequency scheduling There are restrictions.

Therefore, in LTE-Advanced, the DM-RS can be orthogonalized even between terminals having different DM-RS transmission bandwidths and transmission band positions by using Walsh sequences as DM-RS sequences. (For example, refer nonpatent literature 1). As a result, the degree of freedom of frequency scheduling in MU-MIMO multiplexing is improved, and further improvement in system performance can be expected.

The application method of the Walsh sequence to DM-RS, which is being studied by LTE-Advanced, is as follows. In LTE-Advanced (or LTE), DM-RSs are arranged in two slots in one subframe, and two DM-RSs are transmitted in one subframe. The terminal (transmission side) multiplies each of the two DM-RSs in one subframe by a Walsh sequence having a sequence length of 2 (for example, (1, 1) or (1, −1)). On the other hand, the base station (receiving side) multiplies each of the two DM-RSs in one subframe by the same Walsh sequence as that of the terminal (transmitting side), and adds the multiplied DM-RSs in phase. Here, if there is no channel time variation between two DM-RSs in one subframe, the DM-RS from a certain terminal is added in-phase, so that the Walsh sequence different from the Walsh sequence multiplied by the DM-RS is obtained. The DM-RS (interference component) multiplied by the sequence is out of phase. As a result, the interference component can be completely canceled. In this way, even if the transmission bandwidth or transmission band position of the DM-RS is different, if there is no time variation of the channel, the DM-RS of each terminal is multiplied by a different Walsh sequence so that the DM-RS between the terminals is multiplied. RS can be orthogonalized.

As described above, when applying the Walsh sequence to the DM-RS, the base station uses the sequence number of the Walsh sequence used by each terminal (for example, the sequence number 0 of the Walsh sequence (1, 1) or the Walsh sequence (1 , -1) in order to instruct each terminal to add 1 bit of a signaling bit indicating a Walsh sequence number to the downlink control channel (PDCCH (Physical Downlink Control Channel in LTE)) There is a need.

In this case, since the number of signaling bits from the base station to each terminal increases, it is necessary to newly add a control channel format. As the number of control channel formats increases, the amount of reception processing required for format detection at the terminal increases. Further, when the number of signaling bits from the base station to each terminal increases, the system overhead increases in proportion to the number of terminals scheduled by the base station (that is, the number of control channels), and the throughput performance decreases.

An object of the present invention is to provide a terminal, a base station, and a sequence number determination method capable of preventing an increase in the number of signaling bits from a base station to a terminal even when a Walsh sequence is applied to DM-RS in LTE-Advanced. The purpose is to provide.

The terminal of the present invention is used in a radio communication system in which any of a plurality of transmission parameters is set for each of a plurality of terminals, and the set transmission parameters are notified from the base station to the plurality of terminals. A transmission parameter set in the terminal, which is notified from the base station, based on a correspondence relationship in which the plurality of transmission parameters and Walsh sequence numbers are associated one-to-one. A configuration is provided that includes a determining unit that determines a sequence number of a corresponding Walsh sequence, and a multiplying unit that multiplies the reference sequence for the Walsh sequence having the determined sequence number.

The base station of the present invention is used in a radio communication system in which any one of a plurality of transmission parameters is set for each of a plurality of terminals, and the set transmission parameters are notified from the base station to the plurality of terminals. The base station apparatus is a transmission that notifies the transmission source terminal of the received reference signal based on a correspondence relationship in which the plurality of transmission parameters and sequence numbers of Walsh sequences are associated one-to-one. A determining unit that determines a sequence number of the Walsh sequence corresponding to the parameter; a multiplying unit that multiplies the reference sequence signal by the determined Walsh sequence of the sequence number; and an in-phase addition process for the multiplied reference signal. And an in-phase addition unit for performing the configuration.

The sequence number determination method of the present invention is a wireless communication system in which any one of a plurality of transmission parameters is set for each of a plurality of terminals, and the set transmission parameters are notified from the base station to the plurality of terminals. The transmission parameter notified from the base station to the terminal based on a correspondence relationship in which the plurality of transmission parameters and the sequence numbers of the Walsh sequence are associated one-to-one. The sequence number of the Walsh sequence corresponding to is determined.

According to the present invention, it is possible to prevent an increase in the number of signaling bits from a base station to a terminal even when a Walsh sequence is applied to DM-RS in LTE-Advanced.

The block diagram which shows the structure of the terminal which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. The figure which shows the correspondence of the transmission bandwidth (RB number) which concerns on Embodiment 1 of this invention, and a Walsh sequence number. The figure which shows the fine adjustment process of the transmission bandwidth which concerns on Embodiment 1 of this invention. The figure which shows the setting process of CS amount which concerns on Embodiment 1 of this invention The figure which shows the correspondence of the transmission bandwidth (RBG number) and Walsh sequence number concerning Embodiment 1 of this invention. The figure which shows the moving average process which concerns on Embodiment 2 of this invention The figure which shows the change of the average SINR which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 2 of this invention. The figure which shows the correspondence of the transmission bandwidth (RB number) which concerns on Embodiment 2 of this invention, and a Walsh sequence number. The figure which shows the detection window of the ZC series which concerns on Embodiment 2 of this invention (when transmission bandwidth is small) The figure which shows the detection window of the ZC series which concerns on Embodiment 2 of this invention (when transmission bandwidth is large) The figure which shows the correspondence of the transmission bandwidth (RB number), CS number, and Walsh sequence number concerning Embodiment 2 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 3 of this invention. The figure which shows the correspondence of the transmission band position (RB number) which concerns on Embodiment 3 of this invention, and a Walsh sequence number. The figure which shows the fine adjustment process of the transmission band position (RB number) based on Embodiment 3 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 4 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 4 of this invention. The figure which shows the correspondence of the MCS number which concerns on Embodiment 4 of this invention, and a Walsh sequence number The figure which shows the correspondence of the TBS number and Walsh sequence number which concern on Embodiment 4 of this invention. The block diagram which shows the structure of the terminal which concerns on Embodiment 5 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 5 of this invention. The figure which shows the example of allocation of the transmission resource which concerns on Embodiment 5 of this invention. The figure which shows the variation of Embodiment 5 of this invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the radio communication system according to each embodiment of the present invention, for each of a plurality of terminals, one of a plurality of transmission parameters that can be set for each terminal is set, and the set transmission parameter is a base station. Is notified to multiple terminals.

(Embodiment 1)
In the present embodiment, the DM-RS transmission bandwidth is associated with the Walsh sequence number (Walsh sequence number) on a one-to-one basis.

The configuration of terminal 100 according to the present embodiment will be described with reference to FIG.

The reception RF unit 102 of the terminal 100 shown in FIG. 1 performs reception processing such as down-conversion and A / D conversion on the signal received via the antenna 101, and outputs the signal subjected to the reception processing to the demodulation unit 103. The received signal includes scheduling information including transmission parameters indicating the transmission band position and transmission bandwidth (number of RSs) of signals (data and DM-RS) transmitted by terminal 100.

Demodulation section 103 performs demodulation processing on the scheduling information included in the signal input from reception RF section 102, and outputs the demodulated scheduling information to transmission band position setting section 104 and transmission bandwidth setting section 105. To do.

Transmission band position setting section 104 extracts a transmission band position of a signal (data and DM-RS) transmitted by the terminal included in scheduling information input from demodulation section 103, and maps the extracted transmission band position to mapping section Output to 109.

Transmission bandwidth setting section 105 extracts the transmission bandwidth of signals (data and DM-RS) transmitted by the terminal included in the scheduling information input from demodulation section 103, and generates the extracted transmission bandwidth. 106 and the determination unit 107.

The generation unit 106 is a DM-RS sequence having a sequence length corresponding to the transmission bandwidth input from the transmission bandwidth setting unit 105 (ZC (Zadoff-Chu) sequence in LTE. In the following description, a ZC sequence is used). ) Is generated. Then, generation unit 106 outputs the generated ZC sequence to multiplication unit 108.

The determination unit 107 has a rule table indicating a correspondence relationship in which a DM-RS transmission bandwidth (number of RBs) defined in advance for each cell or system is associated with a Walsh sequence Walsh sequence number on a one-to-one basis. . Then, the determination unit 107 refers to the rule table according to the transmission bandwidth input from the transmission bandwidth setting unit 105, and determines the Walsh sequence number (for example, the Walsh sequence (1, 1) Walsh sequence) used by the terminal. The sequence number 0 or Walsh sequence number 1) of the Walsh sequence (1, −1) is determined. That is, the determination unit 107 has a one-to-one correspondence relationship between a plurality of transmission parameters indicating transmission bandwidths of signals (data and DM-RS) transmitted by each terminal and a Walsh sequence Walsh sequence number. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (here, the transmission bandwidth) addressed to the terminal notified from the base station is determined. Then, the determination unit 107 outputs the determined Walsh sequence number to the multiplication unit 108. Note that the correspondence (rule table) between the transmission bandwidth and the Walsh sequence number of the determination unit 107 will be described later.

The multiplication unit 108 multiplies the Walsh sequence of the Walsh sequence number input from the determination unit 107 by the ZC sequence (DM-RS sequence) input from the generation unit 106. Specifically, multiplication section 108 uses the Walsh sequence (sequence length 2) of the Walsh sequence number input from determination section 107 as a DM-RS ZC sequence arranged in each of two slots in one subframe. Multiply by. Multiplying section 108 then outputs the ZC sequence after the Walsh sequence multiplication to mapping section 109.

Mapping section 109 maps the ZC sequence input from multiplication section 108 to a band corresponding to the transmission band of terminal 100 based on the transmission band position of the signal of terminal 100 input from transmission band position setting section 104. . Then, mapping section 109 outputs the mapped ZC sequence to IFFT section 110.

The IFFT unit 110 performs IFFT processing on the ZC sequence input from the mapping unit 109. Then, IFFT section 110 outputs the ZC sequence subjected to IFFT processing to CP (Cyclic Prefix) adding section 111.

CP adding section 111 adds the same signal as the tail part of the ZC sequence input from IFFT section 110 to the head as CP, and outputs the ZC sequence after the CP addition to transmission RF section 112.

Transmission RF section 112 performs transmission processing such as D / A conversion, up-conversion, amplification, etc. on the ZC sequence input from CP adding section 111, and uses the signal subjected to the transmission processing as a DM-RS from antenna 101 to the base station Send to.

Note that terminal 100 performs encoding processing and modulation processing on transmission data, and assigns the transmission data to a band corresponding to the transmission band of terminal 100. Then, terminal 100 multiplexes transmission data allocated to a band corresponding to the transmission band of terminal 100 with a ZC sequence (DM-RS) (eg, time multiplexing), and transmits the multiplexed signal to the base station (FIG. Not shown).

Next, the configuration of base station 200 according to the present embodiment will be described using FIG.

The reception RF unit 202 of the base station 200 shown in FIG. 2 performs reception processing such as down-conversion and A / D conversion on the signal received via the antenna 201 and outputs the signal subjected to reception processing to the CP removal unit 203. To do.

CP removal section 203 removes the CP component added to the head of the signal input from reception RF section 202 and outputs the signal after CP removal to separation section 204.

The separation unit 204 separates the signal input from the CP removal unit 203 into DM-RS and data signal. Then, the separation unit 204 outputs the separated DM-RS to the FFT (Fast Fourier transform) unit 205, and outputs the data signal to the FFT unit 217.

The FFT unit 205 performs FFT processing on the time-domain DM-RS input from the separation unit 204 and converts the time-domain to frequency-domain signal. Then, the FFT unit 205 outputs the DM-RS converted into the frequency domain to the demapping unit 207.

Transmission band position setting section 206 transmits the same transmission band position as the signal (data and DM-RS) transmission band position (ie, the transmission band of terminal 100) instructed by base station 200 to terminal 100 (FIG. 1). The same value as the transmission band position used in the position setting unit 104) is set in the demapping unit 207 and the demapping unit 218.

Based on the transmission band position input from transmission band position setting section 206, demapping section 207 extracts the DM-RS corresponding to the transmission band of the desired terminal from the DM-RS in the frequency domain input from FFT section 205. To do. Then, the demapping unit 207 outputs the extracted DM-RS to the multiplication unit 211.

Transmission bandwidth setting section 208 has the same transmission bandwidth as the transmission bandwidth of the signals (data and DM-RS) that base station 200 has instructed to terminal 100 (FIG. 1) (that is, the transmission bandwidth of terminal 100). The transmission bandwidth used in the width setting unit 105 is set to the determination unit 209 and the generation unit 210.

The determination unit 209 has the same rule table as the rule table included in the determination unit 107 (FIG. 1) of the terminal 100. Then, the determination unit 209 refers to the rule table according to the transmission bandwidth input from the transmission bandwidth setting unit 208, and determines the Walsh sequence number used by the terminal 100 (for example, the Walsh sequence (1, 1)). The Walsh sequence number 0 or the Walsh sequence number 1) of the Walsh sequence (1, −1) is determined. That is, the determination unit 209 has a one-to-one correspondence relationship between a plurality of transmission parameters indicating transmission bandwidths of signals (data and DM-RS) transmitted from each terminal and a Walsh sequence Walsh sequence number. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (in this case, the transmission bandwidth) notified to the received DM-RS transmission source terminal 100 is determined based on. Then, the determination unit 209 outputs the determined Walsh sequence number to the multiplication unit 211. Note that the correspondence relationship (rule table) between the transmission bandwidth and the Walsh sequence number of the determination unit 209 will be described later.

Generating section 210 generates a DM-RS sequence (ZC sequence) having a sequence length corresponding to the transmission bandwidth input from transmission bandwidth setting section 208 in the same manner as generating section 106 (FIG. 1) of terminal 100. To do. Then, generation unit 210 outputs the generated ZC sequence to division unit 213.

The multiplying unit 211 multiplies the Walsh sequence of the Walsh sequence number input from the determining unit 209 by the DM-RS input from the demapping unit 207. Specifically, the multiplication unit 211 multiplies the Walsh sequence (sequence length 2) of the Walsh sequence number input from the determination unit 107 by the DM-RS respectively arranged in two slots in one subframe. Then, multiplier 211 outputs the DM-RS (that is, two DM-RSs) of each slot after the Walsh sequence multiplication to in-phase adder 212.

The in-phase addition unit 212 performs in-phase addition of the two DM-RSs input from the multiplication unit 211, and outputs the signal after the in-phase addition to the division unit 213.

The division unit 213 divides the signal input from the in-phase addition unit 212 by the ZC sequence (DM-RS sequence) input from the generation unit 210. Then, the division unit 213 outputs the division result (correlation value) to the IFFT (Inverse Fast Fourier Transform) unit 214.

The IFFT unit 214 performs IFFT processing on the signal (division result) input from the division unit 213. Then, IFFT unit 214 outputs the signal subjected to IFFT processing to mask processing unit 215.

The mask processing unit 215 performs a mask process on the signal input from the IFFT unit 214 to obtain a correlation value of a section (detection window or window portion) where a correlation value of a desired CS (cyclic shift) sequence exists. Extract. Then, the mask processing unit 215 outputs the extracted correlation value to a DFT (Discrete Fourier Transform) unit 216.

The DFT unit 216 performs DFT processing on the correlation value input from the mask processing unit 215. Then, the DFT unit 216 outputs the correlation value subjected to the DFT process to the frequency domain equalization unit 219. Note that the signal output from the DFT unit 216 is a signal representing the frequency fluctuation of the propagation path (frequency response of the propagation path).

Meanwhile, the FFT unit 217 performs FFT processing on the data signal in the time domain input from the separation unit 204, and converts the signal from the time domain to the frequency domain. Then, the FFT unit 217 outputs the data signal converted into the frequency domain to the demapping unit 218.

The demapping unit 218 extracts a data signal corresponding to the transmission band of the desired terminal from the signal input from the FFT unit 217 based on the transmission band position input from the transmission band position setting unit 206. Then, the demapping unit 218 outputs each extracted data signal to the frequency domain equalization unit 219.

The frequency domain equalization unit 219 performs equalization processing on the data signal input from the demapping unit 218 using the signal input from the DFT unit 216 (frequency response of the propagation path). Then, the frequency domain equalization unit 219 outputs the equalized signal to the IFFT unit 220.

The IFFT unit 220 performs IFFT processing on the data signal input from the frequency domain equalization unit 219. Then, IFFT section 220 outputs the data signal subjected to IFFT processing to demodulation section 221.

Demodulation section 221 performs demodulation processing on the data signal input from IFFT section 220 and outputs the demodulated data signal to decoding section 222.

The decoding unit 222 performs a decoding process on the data signal input from the demodulation unit 221 and extracts received data.

Note that the base station 200 schedules a transmission band position or a transmission bandwidth of a signal (data and DM-RS) transmitted from each terminal to a plurality of terminals in a cell covered by the base station 200. Then, base station 200 modulates scheduling information indicating a scheduling result, and transmits the modulated scheduling information to each terminal using a downlink control channel (not shown).

Next, an example of setting a Walsh sequence Walsh sequence number in the determining unit 107 (FIG. 1) of the terminal 100 and the determining unit 209 (FIG. 2) of the base station 200 will be described.

In the following description, as a transmission bandwidth (number of RBs) of signals (data and DM-RS) of each terminal, a transmission bandwidth (1 RB = 180 kHz in LTE) where the prime factor of the number of RBs is 2, 3, and 5 is used. Use. Specifically, as shown in FIG. 3, 35 transmission bandwidths of 1 RB, 2 RB, 3 RB,..., 96 RB, 100 RB, and 108 RB can be set as the transmission bandwidth (number of RBs) of DM-RS. . In FIG. 3, the sequence length of the Walsh sequence is 2, the Walsh sequence number of the Walsh sequence (1, 1) is 0, and the Walsh sequence number of the Walsh sequence (1, −1) is 1.

As shown in FIG. 3, in the present embodiment, the Walsh sequence Walsh sequence number used for DM-RS is set to the DM-RS transmission bandwidth (35 types) that base station 200 can set for each terminal. There is a one-to-one correspondence. The rule table shown in FIG. 3 is held by the determination unit 107 and the determination unit 209.

Therefore, for example, when the DM-RS transmission bandwidth set for terminal 100 is 1 RB, determining section 107 and determining section 209 determine the DM-RS of terminal 100 based on the correspondence shown in FIG. The Walsh sequence number of the Walsh sequence to be used is determined to be 0. Similarly, for example, when the transmission bandwidth of the DM-RS set in terminal 100 is 2 RBs, determination section 107 and determination section 209, based on the correspondence shown in FIG. The Walsh sequence number of the Walsh sequence used for the RS is determined as 1. The same applies to the transmission bandwidths 3RB to 108RB shown in FIG.

In this way, terminal 100 uses DM- based on the transmission bandwidth of signals (data and DM-RS) transmitted by terminal 100, which are transmission parameters transmitted by base station 200 using a downlink control channel. The Walsh sequence used for the RS can be determined.

That is, as shown in FIG. 3, by associating the transmission bandwidth with the Walsh sequence number in advance, the terminal 100 can specify the Walsh sequence used by the terminal 100 without being notified from the base station 200, The signaling bit required for notification of the Walsh sequence number is not necessary. For this reason, even when applying a Walsh sequence to DM-RS in LTE-Advanced, it is possible to prevent an increase in signaling bits of a downlink control channel, and it is not necessary to newly add a control channel format.

Further, in the rule table (correspondence relationship) shown in FIG. 3, different Walsh sequence numbers are associated with the transmission bandwidths having the closest number of RBs. For example, as illustrated in FIG. 3, different

Walsh sequence numbers

0 and 1 are included in a transmission bandwidth 10 RB and a transmission bandwidth 9 RB that is smaller than 10 RBs and the number of RBs is closest to 10 RBs. Each is associated. Similarly, as shown in FIG. 3, different

Walsh sequence numbers

0 and 1 are used for a transmission bandwidth 10 RB and a transmission bandwidth 12 RB having a transmission bandwidth larger than 10 RB and the number of RBs closest to 10 RB. Are associated with each other. That is, when two Walsh sequences (Walsh sequence numbers 0 and 1) are used, as shown in FIG. 3, the transmission bandwidths (number of RBs) are arranged in ascending order of 35 transmission bandwidths (transmission parameters). On the other hand,

Walsh sequence numbers

0 and 1 are associated with each other alternately. That is, in the rule table shown in FIG. 3, for a plurality of transmission parameters (35 transmission bandwidths shown in FIG. 3) representing different qualities (transmission bandwidth), the two transmission parameters indicating the closest quality are used. , Different Walsh sequence numbers are associated with each other.

That is to say, the determination unit 107 and the determination unit 209 respectively set two transmission parameters indicating the closest quality among a plurality of transmission parameters (35 transmission bandwidths shown in FIG. 3) indicating different qualities (transmission bandwidths). The Walsh sequence number associated with the transmission parameter (transmission bandwidth) set in the terminal 100 is determined based on the correspondence relationship in which the associated Walsh sequence numbers are different from each other.

Here, there is a case where the base station 200 (scheduler) schedules transmission bandwidths having different transmission bandwidths and having the same associated Walsh sequence number to a plurality of terminals. In this case, since a Walsh sequence having the same Walsh sequence number is used for the DM-RS of each terminal, there is a restriction that DM-RSs between terminals cannot be orthogonalized. For example, as illustrated in FIG. 4, the base station 200 sets a transmission bandwidth 6RB for the terminal A and sets a transmission bandwidth 4RB (the broken line portion illustrated in FIG. 4) for the terminal B. In this case, as shown in FIG. 3, the Walsh sequence Walsh sequence numbers used for the DM-RSs of terminal A and terminal B are both 1 (W # 1 shown in FIG. 4).

However, the base station 200 (scheduler) can control the transmission bandwidth of each terminal. Therefore, when the transmission bandwidth differs between terminals and the Walsh sequence number of the Walsh sequence used for DM-RS between the terminals is the same (W # 1 in FIG. 4), the base station 200 (scheduler) Fine-tune the transmission bandwidth setting of one terminal. Specifically, the base station 200 sets the transmission bandwidth of one of the two terminals having different transmission bandwidths set and the same Walsh sequence number associated with the transmission bandwidth. Is increased or decreased by 1 RB. For example, as shown in FIG. 4, base station 200 reduces terminal B's transmission bandwidth 4RB (broken line portion shown in FIG. 4) by 1 RB and resets it to 3RB (solid line portion shown in FIG. 4). Thereby, the Walsh sequence Walsh sequence number used for the DM-RS of terminal B shown in FIG. 4 is 0 (W # 0 shown in FIG. 4) with reference to FIG. That is, the Walsh sequence Walsh sequence number used for the DM-RS of the terminal B (W # 0 shown in FIG. 4) and the Walsh sequence Walsh sequence number used for the DM-RS of the terminal A (W # 1 shown in FIG. 4). Can be different from each other.

Here, among the 35 transmission bandwidths shown in FIG. 3, the reception quality of the DM-RS hardly changes between the transmission bandwidths having the closest number of RBs. For example, as shown in FIG. 4, regardless of whether terminal B uses transmission bandwidth 4RB or transmission bandwidth 3RB, the difference between the two transmission bandwidths is only 1 RB (1RB = 180 kHz in LTE). The reception quality of the DM-RS transmitted by the terminal 100 is almost the same. In other words, in FIG. 3, the transmission bandwidth set for the terminal is shifted by one settable transmission bandwidth, and the transmission bandwidth can be accommodated while minimizing the change in DM-RS reception quality. The attached Walsh sequence number can be inverted. For this reason, the base station 200 (scheduler) has little influence on the system throughput performance by finely adjusting the transmission bandwidth set for one terminal in order to orthogonalize the DM-RS between the terminals.

That is, even when the transmission bandwidth differs between terminals and the Walsh sequence number of the Walsh sequence used for the DM-RS between the terminals is the same (W # 1 in FIG. 4), the base station 200 can Is shifted by one settable transmission bandwidth, the DM-RS between terminals can be orthogonalized without degrading the reception quality of the DM-RS transmitted by the terminal 100. .

Note that when the base station 200 finely adjusts the transmission bandwidth of the terminal 100, the reception quality of the signals (data and DM-RS) transmitted by the terminal is adjusted by simultaneously finely adjusting the data coding rate or transmission power. The decrease can be suppressed. For example, when the base station 200 (scheduler) reduces the transmission bandwidth of the terminal 100 from 4 RBs to 3 RBs in order to orthogonalize DM-RSs between terminals, the data coding rate may be increased to 4/3 times. Good. Alternatively, when base station 200 (scheduler) reduces the transmission bandwidth of terminal 100 from 4 RBs to 3 RBs in order to orthogonalize DM-RSs between terminals, the desired SINR that satisfies the required quality increases due to the reduction of the transmission bandwidth. The transmission power of data may be increased by that amount. Thereby, when the transmission power of the terminal 100 has a surplus, the reception quality of the signal transmitted by the terminal can be maintained without reducing the data transmission rate.

Also, as shown in FIG. 5, the base station 200 (scheduler) may schedule the same transmission bandwidth (6 RB in FIG. 5) for each terminal. In this case, the Walsh sequence having the same Walsh sequence number (W # 1 in FIG. 5) is used for the DM-RS of each terminal. Therefore, the base station 200, as shown in FIG. 5, between terminals having the same transmission bandwidth, has different CS amounts (in FIG. 5, CS # 0 and terminal B in terminal A as in LTE). CS # 1) is set. Thereby, even when the transmission bandwidth between terminals is the same, DM-RSs between terminals can be orthogonalized.

Thus, according to the present embodiment, the DM-RS transmission bandwidth and the Walsh sequence Walsh sequence number are associated one-to-one. Thereby, the terminal can specify the Walsh sequence used for the DM-RS of the terminal based on the transmission bandwidth of the signal (data and DM-RS) of each terminal, which is the transmission parameter notified by the base station. it can. Therefore, according to the present embodiment, in LTE-Advanced, even when a Walsh sequence is applied to DM-RS, it is possible to prevent an increase in the number of signaling bits required for notification of the Walsh sequence number from the base station to the terminal. This eliminates the need to newly add a control channel format.

Furthermore, according to the present embodiment, among the transmission bandwidths that can be set for each terminal, between different transmission bandwidths, that is, between transmission bandwidths of the closest quality, different Walsh sequence numbers. It is associated. Thus, when different transmission bandwidths are set for a plurality of terminals, even if the Walsh sequence numbers associated with the transmission bandwidths are the same, the base station (scheduler) is assigned to one terminal. Fine-tune (increase / decrease) the set transmission bandwidth by one. As a result, DM-RSs between terminals can be orthogonalized without degrading the reception quality of DM-RSs transmitted by terminals with finely adjusted transmission bandwidths. That is, the degree of freedom of frequency scheduling in MU-MIMO multiplexing can be ensured.

In the present embodiment, as shown in FIG. 3, a case has been described in which

Walsh sequence numbers

0 and 1 are alternately associated with each other over transmission bandwidths 1RB to 108RB. However, in the present invention, Walsh sequence

Walsh sequence numbers

1 and 0 may be alternately associated over transmission bandwidths 1RB to 108RB (that is, 0 is inverted to 1 in FIG. 3 and 1 is set to 0). May be reversed).

In the present embodiment, the case where the number of RBs is used as the transmission bandwidth has been described. However, the transmission bandwidth is not limited to the case where the number of RBs is used. For example, when the transmission bandwidth of each terminal is set in units of RBG (Resource Block Group) in which a plurality of RBs are combined, such as transmission frequency resource allocation (for example, Type 0 allocation) used in the LTE downlink. May use the number of RBGs as the transmission bandwidth. For example, as shown in FIG. 6, the number of RBGs that are transmission bandwidths (that is, the total number of RBGs assigned to each terminal) and the Walsh sequence Walsh sequence numbers may be associated on a one-to-one basis. Also, as shown in FIG. 6, different Walsh sequence numbers may be associated with the transmission bandwidths having the closest number of RBGs in the same manner as in FIG. Thereby, when the base station (scheduler) sets different transmission bandwidths for a plurality of terminals, even if the Walsh sequence numbers associated with the transmission bandwidths are the same, the transmission bandwidth ( The RBG number) may be finely adjusted. That is, the base station can ensure the degree of freedom of frequency scheduling in MU-MIMO multiplexing just by finely adjusting the transmission bandwidth as in the present embodiment.

(Embodiment 2)
In the base station, when performing channel estimation using the DM-RS transmitted from each terminal, moving average processing is performed in the frequency domain in order to reduce noise components. For example, as shown in FIG. 7, the base station performs moving average (5 subcarrier average in FIG. 7) processing for each of a plurality of subcarriers corresponding to the received transmission band of DM-RS.

However, with several subcarriers at both ends of the DM-RS transmission band (4 subcarriers at each end in FIG. 7), the number of subcarriers used for moving average processing (moving average number) is reduced, so that an averaging effect is obtained. In other words, the channel estimation accuracy deteriorates.

Also, as the DM-RS transmission bandwidth is smaller, the ratio of the both end portions (that is, subcarriers whose channel estimation accuracy is degraded) to the entire DM-RS transmission bandwidth increases. That is, the smaller the DM-RS transmission bandwidth, the greater the degradation of channel estimation accuracy.

In other words, in order to make the DM-RSs between terminals orthogonal to each other, as in Embodiment 1, when the base station performs fine adjustment to reduce the transmission bandwidth (for example, FIG. 4), transmission of DM-RSs The smaller the bandwidth is, the greater the influence that the reduction of the transmission bandwidth has on the reception quality of the DM-RS transmitted from the terminal.

Further, in order to make the DM-RSs between terminals orthogonal to each other, when the base station performs fine adjustment to increase the transmission bandwidth as in Embodiment 1, the average channel quality (SINR) of DM-RSs is increased. ) May deteriorate and throughput performance may deteriorate. For example, as shown in FIG. 8, the DM-RS transmission bandwidth is set to 1 RB with respect to the high-quality band selected by the base station based on the channel quality (DM-RS transmission bandwidth is 1 RB in FIG. 8). If it is increased, there is a possibility that the average SINR at 2 RBs after the increase will be lower.

Here, in the fine adjustment to increase the transmission bandwidth by the base station, the smaller the transmission bandwidth of the DM-RS, the larger the ratio of the increase in the transmission bandwidth to the total transmission bandwidth of the DM-RS. That is, in order to make DM-RSs between terminals orthogonal to each other, when the base station performs fine adjustment to increase the transmission bandwidth as in Embodiment 1, the smaller the DM-RS transmission bandwidth, The influence of the increase in the transmission bandwidth on the reception quality of the DM-RS transmitted from the terminal becomes larger.

In addition, a terminal having a small transmission bandwidth is often a terminal having no capacity for transmission power. Therefore, when the required transmission power is increased by increasing the transmission bandwidth, that is, “a transmission power increase amount that increases due to an increase in transmission bandwidth> a transmission power decrease amount that can be suppressed by a decrease in coding rate”. In this case, the terminal becomes insufficient in transmission power, and the reception quality of the DM-RS is further deteriorated.

As described above, when the base station finely adjusts (increases / decreases) the transmission bandwidth in order to orthogonalize the DM-RSs between the terminals as described above, the smaller the transmission bandwidth, The influence of the fine adjustment of the transmission bandwidth on the reception quality of the DM-RS transmitted from the terminal becomes larger.

Therefore, in the present embodiment, when a terminal transmits a plurality of transmission bandwidths that can be set for each terminal and the transmission bandwidth of a signal transmitted by the terminal is larger than a threshold, Similarly, the Walsh sequence number is determined based on a correspondence relationship in which the transmission bandwidth and the Walsh sequence number are associated one-to-one. On the other hand, when a transmission bandwidth of a signal transmitted by the terminal is a transmission bandwidth that is equal to or smaller than a threshold in a plurality of transmission bandwidths that can be set in the terminal, the Walsh sequence number notified from the base station Is used.

FIG. 9 shows the configuration of terminal 300 according to the present embodiment. In FIG. 9, the same components as those shown in FIG.

The threshold setting unit 301 of the terminal 300 illustrated in FIG. 9 sets a DM-RS transmission bandwidth threshold, and outputs the set threshold to the determination unit 302.

First, the determination unit 302 acquires the Walsh sequence number based on the threshold value input from the threshold setting unit 301 by notification (scheduling information) from the base station 400 (described later), or is the same as in the first embodiment. Then, it is determined whether to determine the DM-RS transmission bandwidth and the Walsh sequence number based on a rule table (correspondence) in which the transmission sequence number and the Walsh sequence number are associated one by one. Specifically, when the transmission bandwidth input from the transmission bandwidth setting unit 105 is equal to or less than the threshold input from the threshold setting unit 301, the determination unit 302 includes the Walsh included in the scheduling information input from the demodulation unit 103. Extract the sequence number. On the other hand, when the transmission bandwidth input from the transmission bandwidth setting unit 105 is larger than the threshold input from the threshold setting unit 301, the determination unit 302 has a one-to-one correspondence between the DM-RS transmission bandwidth and the Walsh sequence number. The Walsh sequence number corresponding to the transmission bandwidth input from the transmission bandwidth setting unit 105 is determined based on the correspondence relationship associated with. Then, the determination unit 302 outputs the obtained Walsh sequence number to the multiplication unit 108.

Next, FIG. 10 shows the configuration of base station 400 according to the present embodiment. In FIG. 10, the same components as those shown in FIG.

The threshold setting unit 401 of the base station 400 shown in FIG. 10 sets the same value as the threshold setting unit 301 of the terminal 300 (FIG. 9) as the DM-RS transmission bandwidth threshold, and determines the set threshold. Output to 402.

Based on the threshold value input from threshold value setting unit 401, determination unit 402 includes the Walsh sequence number in scheduling information and notifies terminal 300, or in the same way as in Embodiment 1, the transmission band of DM-RS It is determined whether the width and the Walsh sequence number are determined based on a rule table (correspondence) in which the width and the Walsh sequence number are associated one by one. Specifically, when the transmission bandwidth input from transmission bandwidth setting section 208 is equal to or smaller than the threshold input from threshold setting section 401, determination section 402 determines the Walsh sequence number by scheduling. Then, base station 400 notifies terminal 300 of scheduling information including the determined Walsh sequence number. On the other hand, when the transmission bandwidth input from the transmission bandwidth setting unit 208 is larger than the threshold input from the threshold setting unit 401, the determination unit 402 has a one-to-one correspondence between the DM-RS transmission bandwidth and the Walsh sequence number. The Walsh sequence number corresponding to the transmission bandwidth input from the transmission bandwidth setting unit 208 is determined based on the correspondence relationship associated with. Then, the determination unit 402 outputs the obtained Walsh sequence number to the multiplication unit 211.

Hereinafter, setting examples of Walsh sequence numbers in determination section 302 of terminal 300 (FIG. 9) and determination section 402 of base station 400 (FIG. 10) according to the present embodiment will be described.

In the following description, as shown in FIG. 11, the transmission bandwidth (number of RBs) of signals (data and DM-RS) of each terminal is 1RB, 2RB, 3RB, as in Embodiment 1 (FIG. 3). ..., 35 RBs, 96 RBs, 100 RBs, 108 RBs can be set. In FIG. 11, the sequence length of the Walsh sequence is 2, the Walsh sequence number of the Walsh sequence (1, 1) is 0, and the Walsh sequence number of the Walsh sequence (1, -1) is 1. In FIG. 11, threshold setting section 301 and threshold setting section 401 set 5 RBs as the transmission bandwidth threshold.

As shown in FIG. 11, when the transmission bandwidth input from the transmission bandwidth setting unit 105 or the transmission bandwidth setting unit 208 is larger than the threshold value 5RB (that is, any of the transmission bandwidths 6RB to 108RB), the implementation is performed. As in the first embodiment, the Walsh sequence Walsh sequence number used for DM-RS is associated with the DM-RS transmission bandwidth that base station 400 can set for each terminal on a one-to-one basis. That is, as shown in FIG. 11, among a plurality of transmission bandwidths (35 types) that can be set for each terminal, a part of transmission bandwidths (30 types) having a threshold value larger than 5 RBs and a Walsh sequence number are 1 Corresponding in a pair.

That is, as shown in FIG. 11, the rule table indicating the correspondence between transmission parameters (here, transmission bandwidth) that can be set for each terminal and Walsh sequence Walsh sequence numbers is the transmission parameter (transmission bandwidth) and Walsh. It includes a partial table (correspondence relationship after transmission bandwidth 6RB) in which the sequence number is associated one-to-one. In the partial table shown in FIG. 11, as in Embodiment 1 (FIG. 3), two transmissions indicating the closest quality in a plurality of transmission parameters (transmission bandwidths) representing different qualities (transmission bandwidths) are used. Different Walsh sequence numbers are associated with the parameters.

Therefore, the determination unit 302 and the determination unit 402, when the transmission bandwidth of the signal transmitted by the terminal 300 is larger than the threshold 5RB, the DM-RS of the terminal 300 based on the correspondence relationship (partial table) illustrated in FIG. The Walsh sequence number of the Walsh sequence to be used for is determined.

On the other hand, as shown in FIG. 11, the transmission parameter (transmission bandwidth) in the rule table indicating the correspondence between the transmission parameters (here transmission bandwidth) that can be set in each terminal and the Walsh sequence number of the Walsh sequence, In a table other than the partial table (correspondence relationship after the transmission bandwidth 6RB) that is associated with the Walsh sequence number on a one-to-one basis, the

Walsh sequence number

0 or 1 is assigned to each transmission bandwidth (1RB to 5RB). Both can be set.

Therefore, the determination unit 402 of the base station 400 determines the Walsh sequence number when the transmission bandwidth input from the transmission bandwidth setting unit 208 is equal to or less than the threshold value 5RB (that is, any of the transmission bandwidths 1RB to 5RB). Decide either 0 or 1. Then, the base station 400 notifies the terminal 300 of scheduling information including one signaling bit indicating the Walsh sequence number determined by the determination unit 402. That is, as shown in FIG. 11, out of a plurality of transmission bandwidths (35 types) that can be set for each terminal, the base station 400 uses the Walsh sequence number 0 for a transmission bandwidth (5 types) with a threshold of 5 RB or less. , 1 is arbitrarily selected, and the selected Walsh sequence number is notified to the terminal 300.

Then, when the transmission bandwidth input from the transmission bandwidth setting unit 105 is equal to or less than the threshold value 5 RB, the determination unit 302 of the terminal 300 indicates the Walsh indicated by one signaling bit included in the scheduling information notified from the base station 400. A sequence number (0 or 1) is extracted.

In this way, when the transmission bandwidth of the signal transmitted by terminal 300 is larger than the threshold, terminal 300 determines the Walsh sequence used for DM-RS based on the transmission bandwidth as in the first embodiment. Can be determined. That is, when the transmission bandwidth of the signal transmitted by terminal 300 is larger than the threshold, terminal 300, based on the transmission bandwidth that is the transmission parameter notified by base station 400, as in Embodiment 1. The Walsh sequence used for the DM-RS of the own terminal can be specified. Further, when base station 400 (scheduler) sets different transmission bandwidths for a plurality of terminals, even if the Walsh sequence numbers associated with the transmission bandwidths are the same, Embodiment 1 Similarly, the transmission bandwidth set for one terminal is finely adjusted (increased or decreased) by one. As a result, DM-RSs between terminals can be orthogonalized without degrading the reception quality of DM-RSs transmitted by terminals with finely adjusted transmission bandwidths.

On the other hand, when the transmission bandwidth of the signal transmitted by the terminal 300 is equal to or smaller than the threshold, that is, when the fine adjustment of the transmission bandwidth has a great influence on the reception quality of the DM-RS, the terminal 300 The Walsh sequence number notified from 400 is used. Thereby, base station 400 can flexibly set a Walsh sequence Walsh sequence number (0 or 1) for terminal 300 according to the scheduling status of each terminal. Thereby, when the transmission bandwidth of the signal transmitted by the terminal 300 is equal to or smaller than the threshold value, the base station 400 does not perform fine adjustment of the transmission bandwidth, and thus the terminal 300 uses the optimal transmission bandwidth to perform DM. -RS can be transmitted.

Here, in LTE, the base station notifies each terminal of the CS amount of the ZC sequence used as the DM-RS sequence. For example, in LTE, the maximum number of multiplexed DM-RSs due to the difference in CS amount is assumed to be 6, and 3 bits are used for notification of the CS amount from the base station to the terminal. However, when the DM-RS transmission bandwidth is small, the time attenuation of the received signal level at the base station is moderate compared to when the DM-RS transmission bandwidth is large. For this reason, in order to obtain signal power or to prevent interference with other terminals, the base station needs to increase the DM-RS detection window (increase the CS amount at the terminal). For example, when the DM-RS transmission bandwidth is small, as shown in FIG. 12A, the time attenuation of the received signal level at the base station becomes moderate, and therefore the DM-RS transmission bandwidth is large (see FIG. 12A). Compared with 12B), the detection window of DM-RS is enlarged. For this reason, the realistic maximum multiplexing number that can maintain the reception quality of DM-RS is about 4.

Also, the base station (receiving side) performs FFT processing (

FFT units

205 and 217 shown in FIG. 10) in order to convert the time domain received signal into the frequency domain. Since the FFT process is a process of multiplying a rectangular signal having a transmission bandwidth in the frequency domain, the received signal is a SINC function in the time domain (delay profile). Therefore, the time attenuation of the signal level in the time domain becomes gentler as the received signal has a smaller transmission bandwidth in the frequency domain.

Therefore, when the DM-RS transmission bandwidth is small, it is necessary to increase the CS amount set in the DM-RS, and the maximum multiplexing number is reduced. Therefore, it is necessary to notify the CS amount from the base station to the terminal. The number of signaling bits can be reduced. For example, in LTE, when the maximum multiplexing number that can maintain DM-RS reception quality is 4 when the DM-RS transmission bandwidth is small, the number of signaling bits required for CS amount notification is 3 to 2 bits. Even if it is reduced, the performance of the system is not affected.

Therefore, in the present embodiment, base station 400 further reduces the maximum multiplexing number when the transmission bandwidth of the signal transmitted by terminal 300 is equal to or smaller than the threshold, that is, to maintain the reception quality of DM-RS. In this case, 1 bit of signaling bits required for notification of the Walsh sequence Walsh sequence number is added and 1 bit of signaling bits required for notification of the CS amount is reduced. In other words, the base station 400 adds one bit of signaling bits required for notification of the Walsh sequence Walsh sequence number instead of reducing one bit of signaling bits required for notification of the CS amount.

Specifically, as illustrated in FIG. 13, when the transmission bandwidth of a signal transmitted by terminal 300 is equal to or less than a threshold value 5 RB, base station 400 adds one bit of signaling bits required for notification of a Walsh sequence Walsh sequence number. In addition, the signaling bits required for notification of the CS number (CS amount) are reduced by 1 bit from 3 bits to 2 bits. Further, when the transmission bandwidth of the signal transmitted by terminal 300 is equal to or less than the threshold value 5 RB, terminal 300 changes how to read the signaling bits (3 bits) used for notification of the CS number (CS amount) included in the scheduling information. Thus, both the CS number (2 bits) and the Walsh sequence number (1 bit) are extracted.

That is, as shown in FIG. 13, when the transmission bandwidth of a signal transmitted by terminal 300 is less than or equal to the threshold value 5RB, base station 400 notifies the CS number with 2 bits and the Walsh sequence number with 1 bit. To do. On the other hand, as shown in FIG. 13, when the transmission bandwidth of the signal transmitted by terminal 300 is larger than threshold value 5RB, base station 400 notifies the CS number with 3 bits and does not notify the Walsh sequence number (that is, , 0 bit). That is, in FIG. 13, regardless of the transmission bandwidth of the signal transmitted by terminal 300, the total number of signaling bits for reporting both information of the CS number and the Walsh sequence number is 3 bits. .

Accordingly, when the fine adjustment of the transmission bandwidth of the signal transmitted by the terminal 300 has a great influence on the reception quality of the DM-RS, that is, when the transmission bandwidth of the signal transmitted by the terminal 300 is equal to or less than the threshold, When notifying the Walsh sequence Walsh sequence number from the station 400 to the terminal 300, the number of signaling bits required for the notification of the CS number (CS amount) is reduced by the number of signaling bits required for the notification of the Walsh sequence number. As a result, an increase in signaling bits can be prevented.

As shown in FIG. 13, when the transmission bandwidth of the signal transmitted by terminal 300 is equal to or less than the threshold value 5RB, base station 400 uses the Walsh sequence number when reporting the CS number (CS amount) with 2 bits. The CS number (CS amount) pattern to be notified may be changed in association with. For example, Δ is a CS amount setting unit (time length obtained by dividing DM-RS symbol length by 8). In this case, when notifying Walsh sequence number 0 in FIG. 13, base station 400 notifies the CS amount of CS number (0, 2, 4, 6) × Δ in 2 bits, and Walsh sequence number 1 In this case, the CS amount of CS number (1, 3, 5, 7) × Δ is notified by 2 bits. As a result, when MU-MIMO multiplexing is performed between terminals whose transmission bandwidth is equal to or less than the threshold, DM-RSs between terminals have different setting values for both the CS amount and the Walsh sequence number. That is, since the DM-RS between terminals can be orthogonalized in both the ZC sequence and the Walsh sequence, channel estimation accuracy can be further improved and reception quality can be improved.

As described above, according to the present embodiment, the base station provides a Walsh sequence number to a terminal having a small transmission bandwidth such that fine adjustment of the transmission bandwidth has a large influence on the reception quality of DM-RS. (1 bit notification). Further, the base station reduces signaling bits (1 bit reduction) required for notification of the CS amount to a terminal having a small transmission bandwidth. Thereby, it is possible to prevent the reception quality of the DM-RS transmitted by the terminal having a small transmission bandwidth from deteriorating without increasing the signaling bit. Further, when the influence of the fine adjustment of the transmission bandwidth on the reception quality of DM-RS is small, that is, when the transmission bandwidth of the signal transmitted by the terminal is larger than the threshold, the terminal Similarly, the Walsh sequence number can be specified based on the correspondence relationship in which the transmission bandwidth and the Walsh sequence number are associated one-to-one.

In the present embodiment, the transmission bandwidth threshold (5 RBs in FIGS. 11 and 13) may be different for each cell. For example, even if the maximum multiplexing number according to the CS amount varies depending on the cell propagation environment (delay spread, etc.), a threshold suitable for each cell can be set by varying the transmission bandwidth threshold for each cell. Is possible.

(Embodiment 3)
In the present embodiment, the DM-RS transmission band position and the Walsh sequence number are associated one-to-one.

FIG. 14 shows the configuration of terminal 500 according to the present embodiment. In FIG. 14, the same components as those shown in FIG.

The transmission band position of the signal transmitted from the terminal 500 is input from the transmission band position setting unit 104 to the determination unit 501 of the terminal 500 illustrated in FIG. Also, the determination unit 501 has a one-to-one correspondence between a transmission band position (start position or end position) that can be mapped to a DM-RS and defined in advance for each cell or system, and a Walsh sequence Walsh sequence number. A rule table (correspondence). Then, the determination unit 501 refers to the rule table (correspondence) according to the transmission band position input from the transmission band position setting unit 104, and determines the Walsh sequence number (for example, Walsh sequence (1, 1, 1) Walsh sequence number 0 or Walsh sequence (1, -1) Walsh sequence number 1) is determined. That is, the determination unit 501 has a one-to-one correspondence between a plurality of transmission parameters indicating transmission band positions to which signals (data and DM-RS) transmitted from each terminal can be mapped and a Walsh sequence Walsh sequence number. Based on the correspondence relationship, the Walsh sequence Walsh sequence number corresponding to the transmission parameter (the transmission band position in this case) addressed to the terminal notified from the base station is determined. Then, the determination unit 501 outputs the determined Walsh sequence number to the multiplication unit 108.

Next, FIG. 15 shows the configuration of base station 600 according to the present embodiment. In FIG. 15, the same components as those shown in FIG.

15 includes a transmission band position of a signal (data and DM-RS) that the base station 600 has instructed to the terminal 500 (FIG. 14) from the transmission band position setting unit 206. The same transmission band position is input. Further, the determination unit 601 has the same rule table as the rule table included in the determination unit 501 (FIG. 14) of the terminal 500. Then, the determination unit 601 refers to the rule table according to the transmission band position (start position or end position) input from the transmission band position setting unit 206, and determines the Walsh sequence number (for example, Walsh) used by the terminal 500. The Walsh sequence number 0 of the sequence (1,1) or the Walsh sequence number 1) of the Walsh sequence (1, -1) is determined. That is, the determination unit 601 associates a plurality of transmission parameters indicating transmission band positions to which signals (data and DM-RS) transmitted from each terminal can be mapped, and Walsh sequence Walsh sequence numbers on a one-to-one basis. Based on the correspondence relationship, the Walsh sequence Walsh sequence number corresponding to the transmission parameter (here, the transmission band position) notified to the transmission source terminal 500 of the received DM-RS is determined. Then, the determination unit 601 outputs the determined Walsh sequence number to the multiplication unit 211.

Hereinafter, setting examples of Walsh sequence numbers in determination section 501 of terminal 500 (FIG. 14) and determination section 601 of base station 600 (FIG. 15) according to the present embodiment will be described.

In the following description, as shown in FIG. 16, there are six transmission band positions of RB numbers 0 to 5 as transmission band positions (start positions, that is, top RBs) of signals (data and DM-RS) of each terminal. Can be set. Also, in FIG. 16, the sequence length of the Walsh sequence is 2, the Walsh sequence number of the Walsh sequence (1, 1) is 0, and the Walsh sequence number of the Walsh sequence (1, -1) is 1.

As shown in FIG. 16, in the present embodiment, Walsh sequence Walsh sequence numbers used for DM-RS are DM-RS transmission band positions (RB numbers 0 to 5) that can be set for each terminal. There is a one-to-one correspondence. The correspondence between the six transmission band positions (RB numbers 0 to 5) and the Walsh sequence numbers shown in FIG. 16 is held by the determination unit 501 and the determination unit 601.

Therefore, for example, as shown in FIG. 16, the determination unit 501 and the determination unit 601 determine that the DM-RS transmission band position (start position) set in the terminal A is the RB number 0, the DM of the terminal A -Determine the Walsh sequence number of the Walsh sequence used for the RS as 0. Similarly, for example, as illustrated in FIG. 16, the determination unit 501 and the determination unit 601 may, when the DM-RS transmission band position (start position) set in the terminal B is RB number 1, the terminal B The Walsh sequence number used in the DM-RS is determined to be 1. The same applies to RB numbers 2 to 5 shown in FIG.

Thus, terminal 500 (terminal A and terminal B in FIG. 16) transmits signals (data and DM-RS) transmitted by terminal 500, which are transmission parameters transmitted by base station 600 using a downlink control channel. ), The Walsh sequence used for DM-RS can be determined. That is, as shown in FIG. 16, by associating the transmission band position (RB number) and the Walsh sequence number in advance, terminal 500 specifies the Walsh sequence used by the terminal itself without being notified from base station 600. The signaling bit required for notification of the Walsh sequence number is not necessary.

Also, as shown in FIG. 16, different Walsh sequence numbers are associated between the transmission band positions having the closest RB numbers. For example, as shown in FIG. 16, the transmission band position whose start position is RB number 1 and the transmission band positions whose start positions are RB number 0 and RB number 2 closest to RB number 1 are different from each other.

Walsh sequence numbers

1 and 0 are associated with each other. In other words, in FIG. 16, when the RB number of the transmission band position (start position) is an even number (

RB numbers

0, 2, 4), the Walsh sequence number 0 is associated with the RB number of the transmission band position (start position). Is an odd number (

RB numbers

1, 3, 5), Walsh sequence number 1 is associated. That is, when two Walsh sequences (Walsh sequence numbers 0 and 1) are used, as shown in FIG. 16, the Walsh sequence number 0 and the transmission band positions (transmission parameters) arranged in ascending order of the RB numbers. 1 are alternately associated.

Here, there may be a case where the base station 600 (scheduler) schedules transmission band positions having different transmission bandwidths and having the same associated Walsh sequence number to a plurality of terminals. In this case, since a Walsh sequence having the same Walsh sequence number is used for the DM-RS of each terminal, there is a restriction that DM-RSs between terminals cannot be orthogonalized. For example, as shown in FIG. 17, when base station 600 sets the start position of the transmission band position for terminal A and terminal B to RB number 0, the Walsh sequence used for the DM-RS of terminal A and terminal B Both Walsh sequence numbers are 0 (W # 0 shown in FIG. 17).

However, the base station 600 (scheduler) can control the transmission band position of each terminal. Therefore, when the transmission band position is the same between terminals (that is, the Walsh sequence number is the same) (RB number 0, W # 0 in FIG. 17), base station 600 (scheduler) transmits one terminal. Fine-tune the band position setting. Specifically, base station 600 increases or decreases the setting of the transmission band position of one of the two terminals having the same transmission band position (that is, Walsh sequence number) by 1 RB number. For example, as shown in FIG. 17, base station 600 shifts RB number 0 (the broken line portion shown in FIG. 17), which is the transmission band position of terminal B, to RB number 1 (see FIG. 17) by shifting it to the high frequency side by 1 RB. Set to the solid line). As a result, the Walsh sequence Walsh sequence number used for the DM-RS of terminal B shown in FIG. 17 is 1 (W # 1 shown in FIG. 17). That is, the Walsh sequence Walsh sequence number used for the DM-RS of terminal B (W # 1 shown in FIG. 17) and the Walsh sequence Walsh sequence number used for the DM-RS of terminal A (W # 0 shown in FIG. 17). Can be different from each other.

Here, in the transmission band positions of RB numbers 0 to 5 shown in FIG. 17, even if the RB number is shifted by 1 RB (1 RB = 180 kHz in LTE), the reception quality of the DM-RS hardly changes. That is, in FIG. 16, the transmission band position set in the terminal is shifted by one settable transmission bandwidth (that is, 1 RB number) while minimizing the change in DM-RS reception quality. The Walsh sequence number associated with the transmission band position can be inverted. For this reason, the base station 600 (scheduler) finely adjusts the transmission band position (RB number) set for one terminal in order to orthogonalize the DM-RS between the terminals, and the influence on the system throughput performance is Few.

That is, even when the transmission band position is the same between terminals (that is, the Walsh sequence number is the same), the base station 600 shifts the transmission band position (RB number) of one terminal by 1 RB so that the terminal 500 DM-RSs between terminals can be orthogonalized without degrading the reception quality of the DM-RSs transmitted by.

Also, when the transmission band of DM-RS between terminals matches in the same transmission band (that is, the same transmission bandwidth and the same transmission band position), the DM-RS of each terminal is the same The Walsh sequence number (W # 1 in FIG. 5) is used. Therefore, when the DM-RS transmission band between terminals matches in the same transmission band (the same transmission bandwidth and the same transmission band position), base station 600 performs the same as in LTE. Thus, different CS amounts are set. Thereby, even when the transmission bands of DM-RSs between terminals match, DM-RSs between terminals can be orthogonalized.

Thus, according to this embodiment, the DM-RS transmission band position and the Walsh sequence Walsh sequence number are associated one-to-one. Thereby, the terminal can specify the Walsh sequence used for the DM-RS of the terminal based on the transmission band position of the signal (data and DM-RS) of each terminal, which is the transmission parameter notified by the base station. it can. Therefore, according to the present embodiment, in LTE-Advanced, even when a Walsh sequence is applied to DM-RS, it is possible to prevent an increase in the number of signaling bits required for notification of the Walsh sequence number from the base station to the terminal. This eliminates the need to newly add a control channel format.

Furthermore, according to the present embodiment, among a plurality of transmission band positions (start position or end position) that can be set for each terminal, between the closest transmission band positions (for example, adjacent RB numbers), Different Walsh sequence numbers are associated. Thereby, when different transmission band positions are set for a plurality of terminals, even if the Walsh sequence numbers associated with these transmission band positions are the same, the base station (scheduler) is assigned to one terminal. Finely adjust (increase / decrease) the set transmission band position by 1 RB. Thereby, DM-RSs between terminals can be orthogonalized without degrading the reception quality of DM-RSs transmitted by terminals with finely adjusted transmission band positions. That is, the degree of freedom of frequency scheduling in MU-MIMO multiplexing can be ensured.

In the present embodiment, as shown in FIGS. 16 and 17, a case has been described in which the RB number at the start position of the transmission band position is associated with the Walsh sequence Walsh sequence number on a one-to-one basis. However, in the present invention, the RB number at the end of the transmission band position may be associated with the Walsh sequence Walsh sequence number on a one-to-one basis.

In the present embodiment, the correspondence between the transmission band position and the Walsh sequence number may be different for each cell. For example, the correspondence relationship may be different between a femto base station and a macro base station having different transmission powers. Between cells having different correspondences, Walsh sequence Walsh sequence numbers used for signals transmitted in the same transmission band are different from each other and orthogonalized, so that inter-cell interference can be reduced.

(Embodiment 4)
In the present embodiment, the MCS (Modulation and Coding Scheme) number (MCS number) set for each terminal is associated with the Walsh sequence number on a one-to-one basis.

FIG. 18 shows the configuration of terminal 700 according to the present embodiment. In FIG. 18, the same components as those shown in FIG.

In the MCS number setting unit 701 of the terminal 700 shown in FIG. 18, the MCS MCS number set for each terminal transmitted from the demodulating unit 103 using the downlink control channel from the base station (described later). The information shown is input. Then, the MCS number setting unit 701 extracts the MCS number of the signal transmitted from the terminal included in the information input from the demodulation unit 103 and outputs the extracted MCS number to the determination unit 702.

The determination unit 702 has a rule table (correspondence relationship) in which the MCS number and the Walsh sequence Walsh sequence number, which are defined in advance for each cell or system, are associated one-to-one. Then, the determination unit 702 refers to the rule table (correspondence) according to the MCS number input from the MCS number setting unit 701, and determines the Walsh sequence number (for example, Walsh sequence (1, 1)) used by the terminal itself. Walsh sequence number 0 or Walsh sequence number (1, −1) Walsh sequence number 1) is determined. That is, the determination unit 702 is based on a correspondence relationship in which a plurality of transmission parameters indicating MCS numbers that can be set in transmission data transmitted by each terminal and a Walsh sequence Walsh sequence number are associated one-to-one. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (in this case, the MCS number) addressed to itself is notified from the base station. Then, the determination unit 702 outputs the determined Walsh sequence number to the multiplication unit 108.

Also, terminal 700 performs encoding processing and modulation processing on transmission data based on the MCS of the MCS number notified from the base station (not shown).

Next, FIG. 19 shows the configuration of base station 800 according to the present embodiment. In FIG. 19, the same components as those shown in FIG.

The MCS number setting unit 801 of the base station 800 shown in FIG. 19 has the same MCS number as the MCS number instructed to the terminal 700 by the base station 800 (that is, the MCS number used in the MCS number setting unit 701 of the terminal 700). The same value) is set in the decoding unit 222 and the determination unit 802.

The determination unit 802 has the same rule table as the rule table included in the determination unit 702 (FIG. 18) of the terminal 700. Then, the determining unit 802 refers to the rule table according to the MCS number input from the MCS number setting unit 801, and the Walsh sequence number used by the terminal 700 (for example, the Walsh sequence (1, 1) Walsh sequence). The number 0 or the Walsh sequence number 1) of the Walsh sequence (1, −1) is determined. That is, the determination unit 802 is based on a correspondence relationship in which a plurality of transmission parameters indicating MCS numbers that can be set in transmission data transmitted by each terminal and a Walsh sequence Walsh sequence number are associated one-to-one. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (here, the MCS number) notified to the DM-RS transmission source terminal 700 is determined. Then, the determination unit 802 outputs the determined Walsh sequence number to the multiplication unit 211.

The decoding unit 222 demodulates the data signal input from the demodulation unit 221 based on the MCS of the MCS number input from the MCS number setting unit 801.

Also, the base station 800 determines the MCS of transmission data transmitted by each terminal for a plurality of terminals in a cell covered by the base station 800. Base station 800 transmits information indicating the MCS number of each terminal's MCS to each terminal using a downlink control channel (not shown).

Next, setting examples of Walsh sequence numbers in determining section 702 of terminal 700 (FIG. 18) and determining section 802 of base station 800 (FIG. 19) according to the present embodiment will be described.

In the following description, 16 types of MCSs with MCS numbers 1 to 16 can be set as MCS of transmission data transmitted by each terminal, as shown in FIG. In FIG. 20, the modulation scheme and the coding rate are set so that the transmission rate (bit rate) increases as the MCS number increases. In FIG. 20, the sequence length of the Walsh sequence is 2, the Walsh sequence number of the Walsh sequence (1, 1) is 0, and the Walsh sequence number of the Walsh sequence (1, −1) is 1.

As shown in FIG. 20, in the present embodiment, the Walsh sequence Walsh sequence number used for DM-RS is 1 in the MCS MCS numbers (MCS numbers 1 to 16) that can be set in the transmission data transmitted by each terminal. Corresponding in a pair. The rule table illustrated in FIG. 20 is held by the determination unit 702 and the determination unit 802.

Therefore, for example, when the MCS number set in terminal 700 is 1 (modulation scheme: QPSK, coding rate: 1/8), determination section 702 and determination section 802 are based on the correspondence shown in FIG. Then, the Walsh sequence number of the Walsh sequence used for the DM-RS of terminal 700 is determined to be 0. Similarly, for example, when the MCS number set in the terminal 700 is 2 (modulation method: QPSK, coding rate: 1/6), the determination unit 702 and the determination unit 802 correspond to the correspondence relationship illustrated in FIG. Based on, the Walsh sequence Walsh sequence number used for the DM-RS of terminal 700 is determined to be 1. The same applies to MCS numbers 3 to 16 shown in FIG.

Thus, terminal 700 determines a Walsh sequence used for DM-RS based on the MCS number of transmission data transmitted by terminal 700, which is a transmission parameter transmitted by base station 800 using a downlink control channel. can do. That is, as shown in FIG. 20, by associating the MCS number and the Walsh sequence number in advance, the terminal 700 can identify the Walsh sequence used by the terminal without being notified from the base station 800, and the Walsh The signaling bit required for notification of the sequence number is not necessary.

Also, as shown in FIG. 20, among 16 MCSs (MCS numbers 1 to 16) representing different qualities, different Walsh is used between MCSs having the nearest MCS numbers (that is, MCSs representing the nearest quality). A sequence number is associated. For example, as shown in FIG. 20, MCS number 2 and MCS number 1 and MCS number 3 closest to MCS number 2 are associated with different

Walsh sequence numbers

1 and 0, respectively. That is, when two Walsh sequences (Walsh sequence numbers 0 and 1) are used, as shown in FIG. 20, for the MCS numbers (transmission parameters) arranged in ascending order of the transmission rate (bit rate), the

Walsh sequence Numbers

0 and 1 are associated with each other alternately.

Here, the base station 800 (scheduler) may set the same MCS for a plurality of terminals based on the channel quality of each terminal. In this case, since a Walsh sequence having the same Walsh sequence number is used for the DM-RS of each terminal, there is a restriction that DM-RSs between terminals cannot be orthogonalized.

However, the base station 800 (scheduler) can control MCS of transmission data transmitted by each terminal. Therefore, when the MCS numbers of the MCS are the same between terminals (that is, the Walsh sequence numbers are the same), the base station 800 (scheduler) finely adjusts the setting of the MCS number of one terminal. Specifically, base station 800 increases or decreases the setting of the MCS number set for one of the two terminals having the same MCS number by one. As shown in FIG. 20, different Walsh sequence numbers are associated with adjacent MCS numbers, respectively. For this reason, the base station 800 increases or decreases the setting of the MCS number set in one of the two terminals having the same MCS number by one to thereby increase the Walsh used for the DM-RS of both terminals. The Walsh sequence numbers of the sequences can be made different from each other.

Here, in the MCSs with MCS numbers 1 to 16 shown in FIG. 20, if the MCS number is shifted by one, the Walsh sequence Walsh sequence number used for the DM-RS is different, whereas the transmission rate of the transmission data ( Bit rate), that is, the reception performance of the terminal 700 is hardly changed. That is, in FIG. 20, by shifting the MCS number set in the terminal by one, the transmission rate (bit rate) of transmission data, that is, the MCS number while minimizing the change in reception performance of the terminal is minimized. The Walsh sequence number associated with can be reversed. For this reason, the base station 800 (scheduler) has little influence on the system throughput performance by finely adjusting the MCS number set in one terminal in order to orthogonalize the DM-RS between the terminals.

That is, even when the MCS numbers of the MCS are the same between terminals (that is, the Walsh sequence number is the same), the base station 800 shifts the MCS number of one terminal by one so that the reception performance of the terminal 700 is improved. DM-RSs between terminals can be orthogonalized without degrading.

Here, the base station 800 may change the MCS number adjustment (fine adjustment) method for Walsh sequence selection according to the currently set MCS modulation method. For example, QPSK is often set for a terminal having poor channel quality. Therefore, when the currently set MCS modulation scheme is QPSK (MCS numbers 1 to 8 in FIG. 20), base station 800 has a direction of decreasing MCS number (that is, the coding rate is lower, error The MCS number is adjusted so that the tolerance becomes stronger. On the other hand, 16QAM and 64QAM are often set for terminals having good channel quality. Therefore, when the currently set MCS modulation scheme is 16QAM or 64QAM (MCS numbers 9 to 16 in FIG. 20), the base station 800 increases the MCS number (that is, the coding rate is higher). The MCS number is adjusted in the direction of higher throughput. Thereby, it is possible to further reduce the influence of the fine adjustment of the MCS number for the Walsh sequence selection by base station 800 on the reception performance of terminal 700.

As described above, according to the present embodiment, the MCS MCS number set in the transmission data transmitted by the terminal and the Walsh sequence Walsh sequence number are associated one-to-one. Accordingly, the terminal can specify the Walsh sequence used for the DM-RS of the terminal based on the MCS number set for each terminal, which is a transmission parameter notified by the base station. Therefore, according to the present embodiment, in LTE-Advanced, even when a Walsh sequence is applied to DM-RS, it is possible to prevent an increase in the number of signaling bits required for notification of the Walsh sequence number from the base station to the terminal. This eliminates the need to newly add a control channel format.

Furthermore, according to the present embodiment, among the settable MCS numbers, different Walsh sequence numbers are associated between MCS numbers having the closest MCS number, that is, between MCS numbers having the closest quality. . As a result, even when the MCSs set for a plurality of terminals are the same (that is, the Walsh sequence numbers are the same), the base station (scheduler) uses one MCS number set for one terminal. By finely adjusting (increasing / decreasing) only, it is possible to orthogonalize DM-RSs between terminals without degrading the reception performance of terminals with finely adjusted MCS numbers. That is, the degree of freedom of frequency scheduling in MU-MIMO multiplexing can be ensured.

In the present embodiment, as shown in FIG. 20, a case has been described in which

Walsh sequence numbers

0 and 1 are alternately associated with each other over MCS numbers 1 to 16. However, in the present invention,

Walsh sequence numbers

1 and 0 may be alternately associated over MCS numbers 1 to 16 (that is, 0 is inverted to 1 and 1 is set to 0 in FIG. 20). May be reversed).

In this embodiment, instead of the MCS number, a TBS (Transport Block Set) number may be used as shown in FIG. That is, as shown in FIG. 21, a TBS number defined in advance for each cell or system may be associated with a Walsh sequence Walsh sequence number on a one-to-one basis.

(Embodiment 5)
In the present embodiment, terminal IDs that are ID numbers unique to a plurality of terminals are associated with Walsh sequence numbers on a one-to-one basis.

FIG. 22 shows a configuration of terminal 900 according to the present embodiment. In FIG. 22, the same components as those shown in FIG.

Each of the terminal ID setting unit 901 of terminal 900 shown in FIG. 22 is allocated (scheduled) with transmission resources transmitted from demodulating unit 103 using a downlink control channel from a base station (described later). Information indicating the terminal ID set in the terminal is input. Terminal ID setting section 901 extracts the terminal ID of the own terminal included in the information input from demodulation section 103 and outputs the extracted terminal ID to determination section 902.

The determining unit 902 has a rule table (correspondence) in which a terminal ID and a Walsh sequence Walsh sequence number, which are defined in advance for each cell or system, are associated one-to-one. Then, the determination unit 902 refers to the rule table (correspondence) according to the terminal ID input from the terminal ID setting unit 901, and determines the Walsh sequence number (for example, Walsh sequence (1, 1)) used by the terminal itself. Walsh sequence number 0 or Walsh sequence number (1, −1) Walsh sequence number 1) is determined. That is, the determination unit 902 is notified from the base station based on a correspondence relationship in which a plurality of transmission parameters indicating terminal IDs that can be set for each terminal and a Walsh sequence Walsh sequence number are associated one-to-one. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (terminal ID in this case) addressed to the own device is determined. Then, the determination unit 902 outputs the determined Walsh sequence number to the multiplication unit 108.

Next, FIG. 23 shows a configuration of base station 1000 according to the present embodiment. In FIG. 23, the same components as those shown in FIG.

The terminal ID setting unit 1001 of the base station 1000 shown in FIG. 23 has the same terminal ID as the terminal ID instructed to the terminal 900 by the base station 1000 (that is, the terminal ID used in the terminal ID setting unit 901 of the terminal 900). (Same value) is set in the determination unit 1002.

The determining unit 1002 has the same rule table as the rule table included in the determining unit 902 (FIG. 22) of the terminal 900. Then, the determination unit 1002 refers to the rule table according to the terminal ID input from the terminal ID setting unit 1001 and uses the Walsh sequence number used by the terminal 900 (for example, the Walsh sequence (1, 1) Walsh sequence). The number 0 or the Walsh sequence number 1) of the Walsh sequence (1, −1) is determined. That is, the determining unit 1002 receives the received DM-RS based on a correspondence relationship in which a plurality of transmission parameters indicating terminal IDs that can be set for each terminal and a Walsh sequence number of the Walsh sequence are associated one-to-one. The Walsh sequence Walsh sequence number corresponding to the transmission parameter (terminal ID in this case) notified to the transmission source terminal 900 is determined. Then, the determination unit 1002 outputs the determined Walsh sequence number to the multiplication unit 211.

In addition, the base station 1000 controls to which terminal transmission resources are allocated to a plurality of terminals in a cell covered by the base station 1000. Then, base station 1000 sets a terminal ID unique to the terminal to a terminal to which transmission resources are allocated. Base station 1000 transmits information indicating the terminal ID of each terminal to each terminal using a downlink control channel (not shown).

Next, setting examples of Walsh sequence numbers in determining section 902 of terminal 900 (FIG. 22) and determining section 1002 of base station 1000 (FIG. 23) according to the present embodiment will be described.

In the present embodiment, the Walsh sequence Walsh sequence number used for the DM-RS is associated with the terminal ID set for each terminal on a one-to-one basis. For example, as shown in FIG. 24, when the terminal ID is an even number, Walsh sequence number 1 (W # 1 shown in FIG. 24) is associated, and when the terminal ID is an odd number, Walsh sequence number 0 ( W # 0) shown in FIG. 24 is associated.

Therefore, the determination unit 902 and the determination unit 1002 determine the Walsh sequence number of the Walsh sequence used for the DM-RS of the terminal 900 as 0 when the terminal ID set in the terminal 900 is an odd number. Similarly, determining section 902 and determining section 1002 determine that the Walsh sequence Walsh sequence number used for the DM-RS of terminal 900 is 1 when the terminal ID set for terminal 900 is an even number.

As described above, the terminal 900 can determine the Walsh sequence used for the DM-RS based on the terminal ID of the terminal 900, which is a transmission parameter transmitted from the base station 1000 using the downlink control channel. That is, as shown in FIG. 24, by associating the terminal ID and the Walsh sequence number in advance, the terminal 900 can identify the Walsh sequence used by the terminal without being notified from the base station 1000, and the Walsh The signaling bit required for notification of the sequence number is not necessary.

As described above, the determination unit 902 and the determination unit 1002 determine different Walsh sequence numbers depending on whether the terminal ID is an odd number or an even number. That is, the determination unit 902 and the determination unit 1002 determine the same Walsh sequence number between terminals whose terminal IDs are odd (or even). Therefore, when the base station 1000 controls which terminals are allocated to transmission resources, there is a restriction that terminals having terminal IDs that are odd (or even) cannot be allocated to the same transmission band. For example, as shown in FIG. 24, the base station 1000 assigns another terminal with an odd terminal ID to the same transmission band as the terminal B with an odd terminal ID and a transmission bandwidth of 5 RBs. Can not. That is, as shown in FIG. 24, the base station 1000 needs to assign terminal B and terminal C, whose terminal IDs are odd numbers, to different transmission bands. The same applies to terminals with an even terminal ID.

However, when there are many terminals in the cell covered by base station 1000 (when there are many transmission resource allocation candidates), both terminals with odd terminal IDs and terminals with even terminal IDs are sufficient. Exists. Therefore, even when there is a terminal to which the base station 1000 is not assigned due to the restriction, a terminal having a reception performance close to that of the terminal not assigned due to the restriction and having an opposite terminal ID attribute (odd or even) can be assigned. Therefore, there is little impact on system throughput performance.

That is, when there are many terminals in a cell covered by base station 1000 (when there are many transmission resource allocation candidates), base station 1000 allocates terminals to the same transmission resource according to the terminal ID. Even in the case of restricting the DM-RS, it is possible to orthogonalize DM-RSs between terminals without degrading the system throughput performance.

Thus, according to the present embodiment, the terminal ID and the Walsh sequence Walsh sequence number are associated one-to-one. Thereby, the terminal can specify the Walsh sequence used for the DM-RS of the terminal based on the terminal ID, which is the transmission parameter notified by the base station. Therefore, according to the present embodiment, in LTE-Advanced, even when a Walsh sequence is applied to DM-RS, it is possible to prevent an increase in the number of signaling bits required for notification of the Walsh sequence number from the base station to the terminal. This eliminates the need to newly add a control channel format.

Furthermore, according to the present embodiment, when there are many terminals in a cell covered by a base station (when there are many transmission resource allocation candidates), DM-RSs between terminals are orthogonalized. In addition, terminals having different terminal ID attributes are allocated to the same transmission resource. As a result, even when the base station restricts the allocation of terminals to transmission resources according to the terminal ID, the base station uses terminals with different terminal ID attributes that are close to the limited terminal performance as the same transmission resource. Can be assigned. For this reason, even when the base station restricts allocation of terminals to transmission resources according to the terminal ID, it is possible to ensure the degree of freedom of frequency scheduling in MU-MIMO multiplexing.

Note that this embodiment may be combined with Embodiments 1 to 4. That is, the correspondence relationship between the transmission bandwidth, the transmission band position, or the MCS number and the Walsh sequence number may be varied according to the terminal ID. For example, combining the present embodiment and the first embodiment, both the DM-RS transmission bandwidth and the terminal ID may be associated with the Walsh sequence number as shown in FIG. In FIG. 25, the correspondence relationship between the DM-RS transmission bandwidth and the Walsh sequence number differs depending on whether the terminal ID is odd or even. Further, a threshold value may be set for the transmission bandwidth shown in FIG. 25 in the same manner as in the second embodiment. Similarly to the third embodiment, the DM-RS transmission band position may be used instead of the transmission bandwidth shown in FIG. 25. Similarly to the fourth embodiment, the transmission bandwidth shown in FIG. Instead of this, the MCS number (or TBS number) of transmission data transmitted by the terminal may be used.

Further, in FIG. 24, the case has been described in which Walsh sequence number 1 is associated when the terminal ID is an even number, and Walsh sequence number 0 is associated when the terminal ID is an odd number. However, in the present embodiment, when the terminal ID is an even number, Walsh sequence number 0 may be associated, and when the terminal ID is an odd number, Walsh sequence number 1 may be associated.

The embodiments of the present invention have been described above.

In the first to fourth embodiments, the case where MU-MIMO multiplexing is performed has been described. However, not limited to MU-MIMO multiplexing, SU-MIMO (Single-User-MIMO) multiplexing in which the transmission bandwidth, transmission band position, or MCS number of data transmitted by one terminal (transmission side) using a plurality of antennas is different from each other. In addition, the present invention can be similarly applied.

In the above embodiment, the case has been described in which the terminal and the base station have the same rule table in advance and the transmission bandwidth of the DM-RS is associated with the Walsh sequence number. However, the present invention does not require that the terminal and the base station have the same rule table in advance, and if the association equivalent to the association between the transmission bandwidth of the DM-RS and the Walsh sequence number can be performed, It is not necessary to use a table.

In the above embodiment, the correspondence between each transmission parameter (transmission bandwidth, transmission band position, MCS number, and terminal ID) and the Walsh sequence number is not limited even if the base station notifies each terminal to Implicit or Explicit. Good.

Further, although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be realized by software.

Further, each functional block used in the description of each of the above embodiments is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Although referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of advances in semiconductor technology or other derived technology, it is naturally also possible to integrate functional blocks using this technology. Biotechnology can be applied.

The disclosure of the specification, drawings and abstract included in the Japanese application of Japanese Patent Application No. 2009-246807 filed on Oct. 27, 2009 is incorporated herein by reference.

The present invention can be applied to a mobile communication system or the like.

100, 300, 500, 700, 900

Terminal

200, 400, 600, 800, 1000

Base station

101, 201

Antenna

102, 202 Receiving

RF unit

103, 221

Demodulating unit

104, 206 Transmission band

position setting unit

105, 208 Transmission

bandwidth Setting unit

106, 210

Generation unit

107, 209, 302, 402, 501, 601, 702, 802, 902, 1002

Determination unit

108, 211 Multiplication unit 109

Mapping unit

110, 214, 220 IFFT unit 111 CP addition unit 112 Transmission RF Unit 203 CP removal unit 204

separation unit

205, 217

FFT unit

207, 218 demapping unit 212 in-phase addition unit 213 division unit 215 mask processing unit 216 DFT unit 219 frequency domain equalization unit 222

decoding unit

301, 401 threshold setting unit 701 80 MCS

number setting unit

901 and 1001 terminal ID setting unit

Claims

A terminal device used in a communication system in which any one of a plurality of transmission parameters is set for each of a plurality of terminal devices, and the set transmission parameters are notified from the base station device to the plurality of terminal devices. And
The Walsh sequence corresponding to the transmission parameter set in the base station device, which is notified from the base station device, based on the correspondence relationship in which the plurality of transmission parameters and the sequence numbers of the Walsh sequence are associated one-to-one. Determining means for determining the sequence number of
Multiplying means for multiplying the Walsh sequence of the determined sequence number by the reference signal sequence;
A terminal device comprising:
In the correspondence relationship, the different transmission sequence numbers are associated with the two transmission parameters indicating the closest quality,
The terminal device according to claim 1.
The transmission parameter is a transmission bandwidth of a signal transmitted by the terminal device.
The terminal device according to claim 1.
When the transmission parameter set in the own device is a transmission parameter representing the transmission bandwidth larger than a threshold, the determination unit determines a sequence number of the Walsh sequence based on the correspondence relationship and is set in the own device. When the transmission parameter is a transmission parameter representing the transmission bandwidth equal to or less than the threshold, a Walsh sequence number notified from the base station device is used.
The terminal device according to claim 3.
The transmission parameter is a transmission band position to which a signal transmitted by the terminal device is mapped.
The terminal device according to claim 1.
The transmission parameter is an MCS number indicating MCS set in the terminal device, or a TBS number indicating TBS set in the terminal device.
The terminal device according to claim 1.
The transmission parameter is an ID number unique to the plurality of terminal devices.
The terminal device according to claim 1.
For each of a plurality of terminal devices, a base station device that sets one of a plurality of transmission parameters and notifies the plurality of terminal devices of the set transmission parameters,
The sequence number of the Walsh sequence corresponding to the transmission parameter notified to the transmission source terminal device of the received reference signal based on the correspondence relationship in which the plurality of transmission parameters and the sequence number of the Walsh sequence are associated one-to-one. A determination means for determining
Multiplying means for multiplying the reference signal by the determined Walsh sequence of the sequence number;
A base station apparatus comprising:
In-phase addition means for performing in-phase addition processing on the reference signal after the multiplication,
The base station apparatus according to claim 8.
A sequence number determination method used in a base station apparatus that sets one of a plurality of transmission parameters for each of a plurality of terminal apparatuses and notifies the set transmission parameters to the plurality of terminal apparatuses,
Based on the correspondence relationship in which the plurality of transmission parameters and Walsh sequence number are associated one-to-one, the sequence number of the Walsh sequence corresponding to the transmission parameter notified from the base station device to the terminal device is decide,
Sequence number determination method.