JP4744577B2 - Transmitting apparatus and transmitting method - Google Patents

Description

The present invention relates to a transmission apparatus and a transmission method , and more particularly to a transmission apparatus and a transmission method suitable for use in communication that combines an OFDM scheme and an adaptive array antenna.

  In recent years, there is an OFDM (Orthogonal Frequency-Division Multiplexing) system as a radio communication system with good frequency efficiency. The OFDM system is one of multicarrier communication systems, and is a communication system in which subcarriers are arranged so as to be orthogonal to each other, and is characterized by high transmission efficiency.

  Further, there is AAA (Adaptive Antenna Arrays) as a method of transmitting radio signals in a directional manner. In AAA, a signal to be transmitted is multiplied by different weights, and this signal is transmitted from different antennas. As a result, a direction in which a signal transmitted from each antenna is emphasized on the receiving side and a direction in which the signal is weakened are generated, and directional transmission can be performed on the transmitting side.

  When realizing a device that communicates with a plurality of users by combining a communication method that performs directional transmission using such an array antenna and a multi-carrier communication method, there is a problem that the circuit scale increases and the amount of calculation increases. .

  Specifically, the number of processes for multiplying the transmission signal by the weight for directivity transmission is required by the number obtained by multiplying the number of array antennas and the number of subcarriers.

The present invention has been made in view of such a point, and an object thereof is to provide a transmission apparatus and a transmission method that perform directional transmission with a small amount of calculation.

The transmission apparatus of the present invention is a transmission apparatus that weights and transmits N signals corresponding to each of N users, and transmits the M antennas and the N antennas for transmission from the M antennas. Dividing means for dividing the signal into N × M signals; weighting means for weighting each of the N × M signals; and multiplexing the weighted N × M signals for each antenna; Multiplexing means for generating M signals, serial / parallel conversion means for mapping the multiplexed M signals to subcarriers, and transmitting the mapped M signals using the M antennas It employs a configuration in which chromatic transmission means.

The transmission method of the present invention is a transmission method in which N signals corresponding to each of N users are weighted and transmitted, and the N signals are transmitted by N antennas in order to transmit from M antennas. The signal is divided into signals, each of the N × M signals is weighted, the weighted N × M signals are multiplexed for each antenna to generate M signals, and the multiplexed M signals Are mapped to subcarriers, and the mapped M signals are transmitted using the M antennas.

According to the transmission apparatus and the transmission method of the present invention, transmission data is converted from serial data to parallel data, the converted transmission data is multiplied by the weight of directional transmission for each antenna, and the multiplied transmission signal is transmitted to a plurality of carriers. And transmitting from a plurality of antennas, directivity transmission can be performed with a small amount of computation.

  An expected configuration of a directional transmission apparatus that performs communication with a plurality of users using multicarriers that perform directional transmission using an array antenna that is an object of the present invention is shown below.

  FIG. 1 is a block diagram illustrating a configuration of a directional transmission apparatus. The directional transmission apparatus 100 of FIG. 1 includes a MUX 101, an S / P converter 102, an FFT 103, multipliers 104-11 to 104-14, multipliers 104-21 to 104-24, and an adder 105-. 1, an adder 105-2, a guard interval insertion unit 106-1, a guard interval insertion unit 106-2, a transmission RF unit 107-1, a transmission RF unit 107-2, an antenna 108-1, It is mainly composed of the antenna 108-2.

  In FIG. 1, MUX 101 multiplexes a signal to be transmitted to user 1 and a signal to be transmitted to user 2, and outputs the multiplexed transmission signal to S / P converter 102. The S / P converter 102 converts the transmission data from serial data to parallel data, and outputs this transmission data to the FFT 103.

  The FFT 103 performs fast Fourier transform on the transmission data and outputs the transmission data to the multipliers 104-11 to 104-14 and the multipliers 104-21 to 104-24.

  For example, the FFT 103 outputs a transmission signal transmitted to the user 1 on the subcarrier f1 to the multiplier 104-11 and the multiplier 104-21, and transmits a transmission signal transmitted to the user 1 on the subcarrier f3 to the multiplier 104-. 13 and the multiplier 104-23.

  The FFT 103 outputs a transmission signal transmitted to the user 2 on the subcarrier f2 to the multiplier 104-12 and the multiplier 104-22, and transmits a transmission signal transmitted to the user 2 on the subcarrier f4 to the multiplier 104-. 14 and the multiplier 104-24.

  Multipliers 104-11 to 104-14 multiply the transmission signal by a directional transmission weight and output the result to adder 105-1. Specifically, the multiplier 104-11 and the multiplier 104-13 multiply the transmission signal addressed to the user 1 by the directivity weight transmitted from the antenna 108-1, and the multiplier 104-12 and the multiplier 104. −14 multiplies the transmission signal addressed to the user 2 by the directivity weight transmitted from the antenna 108-1.

  Multipliers 104-21 to 104-24 multiply the transmission signal by a directional transmission weight and output the result to adder 105-2. Specifically, the multiplier 104-21 and the multiplier 104-23 multiply the transmission signal addressed to the user 1 by the directivity weight transmitted from the antenna 108-2, and the multiplier 104-22 and the multiplier 104. −24 multiplies the transmission signal addressed to the user 2 by the directivity weight transmitted from the antenna 108-2.

  Adder 105-1 adds the transmission signals output from multipliers 104-11 to 104-14, and outputs the added transmission signals to guard interval insertion section 106-1. Adder 105-2 adds the transmission signals output from multipliers 104-21 to 104-24, and outputs the added transmission signals to guard interval insertion unit 106-2.

  The guard interval insertion units 106-1 and 106-2 add a replica of the transmission signal to the transmission data as a guard interval, and output the added transmission data to the transmission RF units 107-1 and 107-2.

  The transmission RF unit 107-1 converts the transmission signal into a radio frequency and transmits it through the antenna 108-1. Similarly, the transmission RF unit 107-2 converts the transmission signal into a radio frequency and transmits it through the antenna 108-2.

  As shown in the above configuration, the present inventor, when communicating with a plurality of users on a multicarrier that performs directional transmission using an array antenna, has a number of multipliers that multiply a transmission signal by a weight for directional transmission. The present invention has been made by paying attention to the fact that the number of communication partners, the number of array antennas, and the number of subcarriers is multiplied, and the number of required multipliers increases dramatically.

  That is, the essence of the present invention is that in multicarrier communication in which directional transmission is performed using an array antenna, a transmission signal is multiplied by a directional transmission weight for each transmitting antenna, and a transmission signal after weight multiplication is transmitted for each transmitting antenna. It is to reduce the number of multipliers and the circuit scale by superimposing on a plurality of subcarriers.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 2 is a block diagram showing a configuration of the directional transmission apparatus according to Embodiment 1 of the present invention. The directional transmission apparatus 200 of FIG. 2 includes multipliers 201-11, 201-12, multipliers 201-21, 201-22, MUXs 202-1 and 202-2, an S / P converter 203-1. 203-2, FFTs 204-1 and 204-2, adders 205-1 and 205-2, guard interval insertion units 206-1 and 206-2, transmission RF units 207-1 and 207-2, It is mainly composed of antennas 208-1, 208-2.

  In FIG. 2, multipliers 201-11 to 204-22 multiply transmission signals by directional transmission weights and output the result to MUXs 202-1 and 202-2. Specifically, multiplier 201-11 multiplies the transmission signal addressed to user 1 by the directivity weight transmitted from antenna 208-1, and multiplier 201-12 multiplies the transmission signal addressed to user 2 to Multiply by the directivity weight transmitted from the antenna 208-1.

  Similarly, the multiplier 201-21 multiplies the transmission signal addressed to the user 1 by the directivity weight transmitted from the antenna 208-2, and the multiplier 201-22 multiplies the transmission signal addressed to the user 2 to the antenna 208. -2 is multiplied by the directivity weight transmitted.

  The MUX 202-1 multiplexes transmission signals to be transmitted to the user 1 and the user 2 transmitted from the antenna 208-1, and outputs the multiplexed signals to the S / P converter 203-1. Similarly, the MUX 202-2 multiplexes transmission signals transmitted from the antenna 208-2 to the users 1 and 2 and outputs the multiplexed signals to the S / P converter 203-2.

  S / P converters 203-1 and 203-2 convert the transmission signal from serial data to parallel data, and map the transmission data to subcarriers. S / P converters 203-1 and 203-2 output the converted transmission data to FFTs 204-1 and 204-2, respectively.

  FFT 204-1 and FFT 204-2 perform fast Fourier transform on the transmission data, and output the converted transmission data to adder 205-1 and adder 205-2, respectively. For example, the FFT 204-1 and the FFT 204-2 distribute the transmission signal addressed to the user 1 to the subcarriers f1 and f3, and distribute the transmission signal addressed to the user 2 to the subcarriers f2 and f4.

  Adder 205-1 adds the transmission signals output from FFT 204-1, and outputs the added transmission signals to guard interval insertion unit 206-1. Similarly, adder 205-2 adds the transmission signals output from FFT 204-2, and outputs the added transmission signal to guard interval insertion unit 206-2.

  The guard interval insertion units 206-1 and 206-2 add a replica of the transmission signal to the transmission data as a guard interval, and output the added transmission data to the transmission RF units 207-1 and 207-2. The transmission RF units 207-1 and 207-2 convert the transmission signal into a radio frequency and transmit it via the antennas 208-1 and 208-2.

  Here, the multipliers of the directional transmission apparatus 100 in FIG. 1 and the directional transmission apparatus 200 in FIG. 2 are compared. The directional transmission device 100 requires a number of multipliers obtained by multiplying the number of carriers for multiplexing transmission signals by the number of antennas. On the other hand, the directional transmission apparatus 200 requires the number of multipliers obtained by multiplying the number of users and the number of antennas.

  In general, in multicarrier communication, signals are multiplexed on hundreds to thousands of subcarriers. Therefore, when the number of users is smaller than the number of subcarriers, the number of multipliers of directional transmission apparatus 200 is smaller than the number of multipliers of directional transmission apparatus 100.

  As described above, according to the directional transmission device of the present embodiment, the multiplier that multiplies the weights by transmitting the transmission signals after multiplying the weights of the directional transmissions on the plurality of carriers from the plurality of antennas. Can be set to a product of the number of users and the number of antennas, and the communication apparatus with a large number of carriers for multiplexing transmission signals can reduce the device scale.

(Embodiment 2)
FIG. 3 is a block diagram showing a configuration of a directional transmission apparatus according to Embodiment 2 of the present invention. 2 identical to those in FIG. 2 are assigned the same reference numerals as in FIG. 2 and detailed descriptions thereof are omitted.

  The directional transmission apparatus 300 in FIG. 3 converts the transmission data parallel-converted by the S / P converters 301-1 and 301-2 into multipliers 302-11 to 302-14 and multipliers 302-21 to 302-24. The point which multiplies the weight of directivity transmission differs from directivity transmission apparatus 200 of FIG.

  In FIG. 3, the S / P converter 301-1 converts a transmission signal to be transmitted to the user 1 from serial data to parallel data, and maps the transmission data to subcarriers. Then, the S / P converter 301-1 outputs the converted transmission data to the multipliers 302-11 to 302-14. Similarly, the S / P converter 301-2 converts a transmission signal to be transmitted to the user 2 from serial data to parallel data, and maps the transmission data to subcarriers. Then, the S / P converter 301-2 outputs the converted transmission data to the multipliers 302-21 to 302-24.

  Multipliers 302-11 to 302-14 and multipliers 302-21 to 302-24 multiply the transmission signal by weight for each user and carrier, and MUX 303-1 or 303-corresponding to the antenna that transmits this transmission signal. Output to 2.

  For example, the multipliers 302-11 and 302-12 multiply the transmission signal addressed to the user 1 by the weight for transmission from the antenna 208-1 and output the result to the MUX 303-1. Similarly, the multipliers 302-13 and 302-14 multiply the output transmission signal addressed to the user 1 by the weight for transmission from the antenna 208-2, and output the result to the MUX 303-2.

  Multipliers 302-21 and 302-22 multiply the transmission signal addressed to user 2 by the weight used when transmitting from antenna 208-1 and output the result to MUX 303-1. Similarly, the multipliers 302-21 and 302-22 multiply the output transmission signal addressed to the user 2 by the weight for transmission from the antenna 208-2 and output the result to the MUX 303-2.

  The MUX 303-1 multiplexes the transmission signals transmitted from the antenna 208-1 to the user 1 and the user 2, and outputs the multiplexed signals to the FFT 304-1. Similarly, 303-2 multiplexes transmission signals transmitted from antenna 208-2 to user 1 and user 2, and outputs the multiplexed signal to FFT 304-2.

  FFT 304-1 and FFT 304-2 perform fast Fourier transform on the transmission data, and output the converted transmission data to adder 205-1 and adder 205-2, respectively. For example, the FFT 304-1 and the FFT 304-2 distribute the transmission signal addressed to the user 1 to the subcarriers f1 and f3, and distribute the transmission signal addressed to the user 2 to the subcarriers f2 and f4.

  Adder 205-1 adds the transmission signals output from FFT 304-1 and outputs the added transmission signals to guard interval insertion unit 206-1. Similarly, adder 205-2 adds the transmission signals output from FFT 304-2, and outputs the added transmission signals to guard interval insertion unit 206-2.

  Here, the magnitudes of signals calculated by the multipliers of the directional transmission device 100 in FIG. 1 and the directional transmission device 300 in FIG. 3 are compared. Directional transmission apparatus 100 multiplies transmission data after Fourier transform by a weight. In the transmission data after the Fourier transform, one symbol is expressed in multiple values from the transmission data before the Fourier transform. Accordingly, the multiplier is required to have a processing capability for multiplying multi-value transmission data by one multiplication.

  On the other hand, directivity transmitting apparatus 300 multiplies the weight of transmission data before Fourier transform. Transmission data before Fourier transform is transmission data mapped by modulation. For example, in the case of BPSK, the transmission data is a real number of 1 or -1, and in the case of QPSK, the transmission data is a complex number (± 1, ± 1). Therefore, the directional transmission device 300 can perform multiplication processing with a small dynamic range (number of digits).

  As described above, according to the directional transmission device of the present embodiment, the transmission data converted into parallel data is multiplied by the weight of directional transmission for each antenna, and the multiplied transmission signals are superimposed on a plurality of carriers. By transmitting from a plurality of antennas after FFT, the number of digits of the transmission signal to be multiplied by the weight can be reduced, and the amount of calculation for each multiplier can be reduced.

(Embodiment 3)
FIG. 4 is a block diagram showing a configuration of a directional transmission apparatus according to Embodiment 3 of the present invention. 2 identical to those in FIG. 2 are assigned the same reference numerals as in FIG. 2 and detailed descriptions thereof are omitted.

  The directivity transmission apparatus 400 of FIG. 4 is different from that of FIG. 2 in that the addition is performed for each user who transmits a signal of each carrier and for each antenna to be transmitted, and then multiplied by the weight of directivity transmission.

  In FIG. 4, MUX 401 multiplexes a signal to be transmitted to user 1 and a signal to be transmitted to user 2, and outputs the multiplexed transmission signal to S / P converter 402. The S / P converter 402 converts the transmission signal from serial data to parallel data, and maps the transmission data to subcarriers. Then, the S / P converter 402 outputs the converted transmission signal to the FFT 403. The FFT 403 performs fast Fourier transform on the transmission signal and outputs the transmission signal to the adder 404-1 and the adder 404-2.

  The adder 404-1 and the adder 404-2 add the transmission signal output from the FFT 403 for each user who transmits the signal, and add the addition results to the multipliers 405-11, 405-12, 405-21, and 405. Output to -22.

  Specifically, adder 404-1 adds transmission data to be transmitted to user 1 transmitted from antenna 208-1, and outputs the addition result to multiplier 405-11 and adder 405-21. The adder 404-2 adds the transmission data to be transmitted to the user 1, and outputs the addition result to the multiplier 405-12 and the adder 405-22.

  Multiplier 405-11 multiplies the transmission signal addressed to user 1 by the directivity weight transmitted from antenna 208-1, and multiplier 405-12 multiplies the transmission signal addressed to user 2 from antenna 208-1. Multiply the directivity weight to be transmitted. Then, multiplier 405-11 and multiplier 405-12 output the transmission signal to adder 406-1.

  Multiplier 405-21 multiplies the transmission signal addressed to user 1 by the directivity weight transmitted from antenna 208-2, and multiplier 405-22 multiplies the transmission signal addressed to user 2 by antenna 208-. 2 is multiplied by the directivity weight transmitted. Then, multiplier 405-21 and multiplier 405-22 output the transmission signal to adder 406-2.

  Adder 406-1 adds the signals transmitted from antenna 208-1, that is, the transmission signals output from multiplier 405-11 and multiplier 405-12, and adds the added transmission signal to guard interval insertion section 206-1. Output to. Similarly, adder 406-2 adds a signal transmitted from antenna 208-2, that is, a transmission signal output from multiplier 405-21 and multiplier 405-22, and adds the added transmission signal to a guard interval insertion unit. It outputs to 206-2.

  Here, the number of multipliers of the directional transmission apparatus 100 in FIG. 1 and the directional transmission apparatus 400 in FIG. 4 are compared. Directional transmitting apparatus 100 requires a number of multipliers obtained by multiplying the number of subcarriers by the number of antennas. On the other hand, the directional transmission apparatus 400 requires the number of multipliers obtained by multiplying the number of users by the number of antennas.

  Therefore, when the number of users is smaller than the number of subcarriers, the number of multipliers in directional transmission apparatus 400 is smaller than the number of multipliers in directional transmission apparatus 100. In general, in multicarrier communication, the number of subcarriers is several hundred to several thousand, whereas the number of users is several tens.

  Thus, according to the directional transmission apparatus of the present embodiment, after adding for each user transmitting the signal of each carrier and for each transmitting antenna, by multiplying the weight of directional transmission, Signals can be multiplied by weights using the same multiplier, and the number of multipliers can be reduced.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. For example, in the above-described embodiment, the case where the transmission is performed as a directional transmission device has been described. However, the present invention is not limited to this, and the directional transmission can be performed as software.

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

  The program for executing the directional transmission is stored in a computer-readable storage medium, the program stored in the storage medium is recorded in a RAM (Random Access memory) of the computer, and the computer operates according to the program. You may make it let it. Further, it may be mounted and operated on a DSP or the like that executes the directional transmission.

  Moreover, the directional transmission apparatus of the said embodiment is provided in a base station apparatus, and can acquire the same effect.

  In the above description, the Fourier transform and inverse Fourier transform processes can be applied as long as they are orthogonal transform processes. For example, orthogonal transforms such as DCT (Discrete Cosine Transform) and DWT (Discrete Wavelet Transform) may be used.

The present invention is suitable for use in a transmission apparatus suitable for use in communication combining an OFDM scheme and an adaptive array antenna.

Block diagram showing the configuration of a directional transmitter The block diagram which shows the structure of the directional transmission apparatus which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the directional transmission apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the directional transmission apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

201-11, 201-12, 201-21, 201-22, 302-11 to 302-14, 302-21 to 302-24, 405-11, 405-12, 405-21, 405-22 Multiplier 202 -1, 202-2, 303-1, 303-2, 401 MUX
203-1, 203-2, 301-1, 301-2, 402 S / P converters 204-1, 204-2, 304-1, 304-2, 403 FFT
205-1, 205-2, 404-1, 404-2, 406-1, 406-2 Adder 206-1, 206-2 Guard interval insertion unit 207-1, 207-2 RF transmission unit 208-1, 208-2 Antenna

Claims (4)

A transmitter that weights and transmits N signals corresponding to each of N users,
M antennas,
Splitting means for splitting the N signals into N × M signals for transmission from the M antennas;
Weighting means for weighting each of the N × M signals;
Multiplexing means for multiplexing the weighted N × M signals for each antenna to generate M signals;
Serial-parallel conversion means for mapping the multiplexed M signals to subcarriers;
Transmitting means for transmitting the M signals after mapping using the M antennas;
A transmission device. The transmission apparatus according to claim 1, wherein the transmission unit transmits the M transmission signals after mapping by performing Fourier transform individually. A transmission method for weighted transmission of N signals corresponding to each of N users,
Splitting the N signals into N × M signals for transmission from M antennas;
Weight each of the N × M signals;
Multiplexing the weighted N × M signals for each antenna to generate M signals;
Mapping the multiplexed M signals to subcarriers;
A transmission method of transmitting the M signals after mapping using the M antennas. The transmission method according to claim 3, wherein the M transmission signals after mapping are individually Fourier-transformed and transmitted.

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