JP2007060479A - Radio communication method and radio receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a radio communication method for reducing interference waves by a simple adaptive array receiving processing. <P>SOLUTION: In the radio communication method comprised of combination of a receiving means with a transmitting signal estimation means comprised of a transmission path estimation part 111 having a plurality of antennas and a receiving signal composition part 112 and a transmission means for transmitting a signal having a plurality of training symbols (t) equal to the number of antennas of a receiving station at the head of a transmission frame, a weight vector is calculated by W=t/r by performing an adaptive array composition arithmetic operation using the received training symbol as a square matrix (r) and adaptive array composition is performed by a simple arithmetic operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for realizing wireless communication with reduced interference waves in a wireless communication device having at least two or more antennas in the wireless reception device, and more particularly to an adaptive array combining method. .

  As a conventional wireless communication method in which interference waves are reduced, reception means using an MMSE adaptive array is well known. (Refer nonpatent literature 1). This is a method of determining an optimum weight so as to minimize an error between the training signal on the receiving side and the actual array output signal.

  Here, assuming that the transmitted training signal is t and the training symbol portion in the signal received at the receiving station is a matrix r, the weight vector W for adaptive array synthesis is obtained by the equation shown in (Equation 1). Can do.

Here, R _tr represents a dispersion matrix of t and r, and is represented by an equation shown in (Expression 2).

Similarly, R _rr represents the covariance matrix of r, and can be represented by the equation shown in (Expression 3).

  That is, the weight vector W in the (Expression 1) can be obtained by the calculation of the equation shown in the (Expression 4).

“Adaptive signal processing by array antenna” by Nobuyoshi Kikuma November 1998 Science and Technology Publishing (Chapter 3, page 37)

  However, in the conventional weight vector calculation method, multiplication / division of an element number matrix equal to the number of antennas is required four times, and an actual hardware arithmetic circuit is large, so that it is required to be small and inexpensive. It had the subject of being a receiving means unsuitable for consumer products.

  The present invention solves the above-mentioned conventional problems, and realizes a wireless communication method capable of reducing interference waves by simple adaptive array reception processing, thereby enabling wireless communication capable of reducing interference waves that can be implemented in consumer products. It aims to provide a method.

  In order to solve the above-described conventional problem, in the wireless communication method of the present invention, transmission is performed by adding a number of training symbols t equal to the number of antennas of the receiving station to the beginning of the frame. Further, the receiving station treats the training symbol portion of the received signal as a square matrix r, and obtains the weight at the time of synthesis by W = t / r.

  With this configuration, an equivalent adaptive array combining effect can be obtained with a small amount of calculation compared to the original adaptive array combining operation.

  According to the wireless communication apparatus of the present invention, wireless communication with reduced interference waves can be performed by simple adaptive array reception processing.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a wireless communication apparatus and a configuration of packets transmitted and received in Embodiment 1 of the present invention.

  In FIG. 1, reference numeral 101 denotes a wireless transmission device, which generates a modulated transmission signal 102 and transmits it from an antenna 104 through an up-converter 103. Reference numeral 105 denotes a wireless receiver, which includes a first antenna 106 and a second antenna 107. The signal received by the wireless reception device 105 passes through the first down converter 108 and the second down converter 109 connected to the respective antennas and is input to the transmission signal estimation unit 110. The transmission signal estimation unit 110 includes a transmission path estimation unit 111 and a reception signal synthesis unit 112. The transmission path estimation unit 111 calculates an optimal weight vector W for combining signals received from two antennas using a known training signal at the beginning of the received signal frame, and receives the received signal. The signal is output to the signal synthesis unit 112. Based on the weight vector W, the received signal synthesizer 112 weights the signal from each antenna and outputs it as a synthesized signal. The combined signal is demodulated as a transmission signal estimated value 113 in a demodulation circuit at a subsequent stage, and the transmission data is decoded.

In FIG. 1, reference numeral 1001 denotes a frame structure of a transmission signal in Embodiment 1 of the present invention. Here transmission signal frame 1001, the top portion and two training symbols t ₁ and t ₂ are known is added in the receiving station side, which is where t _{1 =} t _2. The modulated transmission data is arranged in the order of x ₁ and x ₂ as transmission data symbols after the two training symbols.

Here, in FIG. 1, the transmission path vector from the antenna 104 on the transmission station side to the first antenna 106 on the reception station side is set to h _1, and similarly, the second antenna 107 on the reception station side from the antenna 104 on the transmission station side. The transmission path vector up to is h ₂ . 1002 shown in FIG. 1, the transmission signal 1001 is a signal format which is received from the first antenna 106 street the receiving station the transmission channel _{h 1,} likewise 1003 is the transmit signal 1001 to the transmission path _{h 2} As shown, the signal format received from the second antenna 107 of the receiving station is shown. Further, reference numeral 1004 shown in FIG. 1 is a combined transmission signal estimation value output from the transmission signal estimation unit 110 of the radio reception apparatus 105. Hereinafter, the combining process in the transmission signal estimation unit 110 of the wireless reception device 105 will be described in detail.

  First, when the training symbol portion in the transmission signal format is represented by a matrix t, (Equation 5) is obtained.

  Next, when the training symbol part in the signal received from each antenna of the receiving station is represented by a matrix r, (Equation 6) is obtained.

Here, elements of received training symbols on the time axis are arranged in the row direction of r, and elements of training symbols for the received antennas are arranged in the column direction. In the present embodiment, each element of r is a first training symbol r ₁₁ received from the first antenna, and r ₁₂ is a second training symbol received from the first antenna, r _21. Is the first training symbol received from the second antenna, and r ₂₂ is the second training symbol received from the second antenna.

The weight vector W for the adaptive array synthesis can be obtained from the received training symbol by the equation shown in (Formula 1). Here, R _tr represents the dispersion matrix of t and r, and is represented by the equation shown in (Expression 2). Similarly, R _rr represents the covariance matrix of r, and the equation shown in (Expression 3). Can be expressed as Therefore, the weight vector W can be obtained by matrix calculation of the equation shown in (Formula 4).

  Here, since the number of training symbols in the signal format is two and the number of antennas on the receiving station side is two, the matrix r in this embodiment always forms a square matrix with two rows and two columns. The From this, the equation shown in (Equation 4) can be expressed by the equation shown in (Equation 7), and an equivalent synthesis result can be obtained with a smaller amount of computation compared to the original adaptive array synthesis. Can do.

Using the weight vector W obtained as described above, the received signal combining section 112 shown in FIG. 1 combines the data symbol portions of the received signal. For example, the first data symbol d ₁ When d ₁ and received from each antenna is a matrix shown in equation (8), the estimated value v ₁ of the transmitted data symbols after synthesis is shown in equation (9) It can be obtained by the formula.

  By performing the same processing for the subsequent data symbols, it is possible to obtain a transmission signal estimated value of the data portion.

  Therefore, according to such a configuration, since the number of training symbols in the signal format is two and the number of antennas on the receiving station side is two, an equivalent synthesis result can be obtained with a small amount of calculation compared to the original adaptive array synthesis. Accordingly, it is possible to provide a wireless communication apparatus that can reduce interference waves.

(Embodiment 2)
Next, processing when the number of antennas exceeds 2 will be described by taking the case of 3 antennas as an example. FIG. 2 is a diagram showing the configuration of the wireless communication apparatus and the configuration of transmitted / received packets in the second embodiment of the present invention. In FIG. 2, the same components as those in FIG.

  In FIG. 2, reference numeral 201 denotes a wireless reception device, which includes a first antenna 202, a second antenna 203, and a third antenna 204. Signals received by the radio reception apparatus 201 pass through the first down converter 205, the second down converter 206, and the third down converter 207 connected to the respective antennas, and are input to the transmission signal estimation unit 208. Is done. As in the first embodiment, the transmission signal estimation unit 208 includes a transmission path estimation unit 209 and a reception signal synthesis unit 210. The transmission path estimation unit 209 calculates an optimal weight vector W for combining signals received from three antennas using a known training signal at the beginning of the received signal frame, and The signal is output to the signal synthesis unit 210. Based on the weight vector W, the received signal synthesizer 210 weights the signal from each antenna and outputs it as a synthesized signal. The combined signal is demodulated as a transmission signal estimated value 211 in a demodulation circuit at a subsequent stage, and the transmission data is decoded.

A frame structure of a transmission signal in Embodiment 2 of the present invention is shown in 2001 of FIG. Here, in the transmission signal frame 2001, training symbols t ₁ , t _2, and t ₃ , which are known on the receiving station side, are added to the head part, where t ₁ = t ₂ = t ₃ . This number of training symbols is included in the transmission signal frame by the number equal to the number of antennas possessed by the counterpart receiving station. The modulated transmission data is arranged in the order of x ₁ and x ₂ as transmission data symbols after the three training symbols.

Further, as in the first embodiment, the transmission path vector from the transmitting station side antenna 104 to the receiving station side first antenna 202 is set to h _1, and similarly, the transmitting station side antenna 104 to the receiving station side The transmission path vector from the second antenna 203 to the second antenna 203 is h ₂ , and the transmission path vector from the transmitting station side antenna 104 to the receiving station side third antenna 204 is h ₃ . 2 is a signal format in which the transmission signal 2001 is received from the first antenna 202 of the receiving station through the transmission path h _1. Similarly, 2003 is the transmission format 2001 in which the transmission signal 2001 is transmitted through the transmission path h ₂ . second received signal format from the antenna 203 of the street the receiving station, 2004 are those which the transmission signal 2001 indicates a signal format which is received from the third antenna 204 of the street the receiving station a channel h ₃ . Further, 2005 in FIG. 2 is a combined transmission signal estimation value output from the transmission signal estimation unit 208 of the wireless reception device 201. Hereinafter, a synthesis process in the transmission signal estimation unit 208 of the wireless reception device 201 will be described.

  First, when the training symbol portion in the transmission signal format is represented by a matrix t, (Equation 10) is obtained.

  Next, when the training symbol part in the signal received from each antenna of the receiving station is represented by a matrix r, (Equation 11) is obtained.

  Hereinafter, the weight vector W for the adaptive array composition can be obtained by the same calculation as that in the first embodiment, and is expressed by the above equation (7).

Using the weight vector W obtained as described above, the data symbol portion of the signal received by the reception signal combining unit 210 shown in FIG. 2 is combined. For example, the first data symbol d ₁ When d ₁ and received from each antenna is a matrix shown in equation (12), the estimated value v ₁ of the transmitted data symbols after synthesis is shown in equation (13) It can be obtained by the formula.

  By performing the same processing for the subsequent data symbols, it is possible to obtain a transmission signal estimated value of the data portion.

  Therefore, according to such a configuration, since the number of training symbols in the signal format is 3 and the number of antennas on the receiving station side is 3, an equivalent synthesis result can be obtained with a small amount of calculation compared to the original adaptive array synthesis. Accordingly, it is possible to provide a wireless communication apparatus that can reduce interference waves.

  Even when the number of antennas at the receiving station is 4 or more, adaptive array combining processing can be performed with a small amount of computation as described above by providing the transmission signal format with the same number of training symbols as the number of antennas. .

(Embodiment 3)
FIG. 3 is a diagram showing the configuration of the wireless communication apparatus and the configuration of packets transmitted and received in the third embodiment of the present invention.

  In FIG. 3, reference numerals 301, 306, and 313 denote wireless communication terminals, which are wireless terminal A, wireless terminal B, and wireless terminal C, respectively. Further, here, the wireless terminal A transmits data to the wireless terminal B and the wireless terminal C.

  The wireless terminal A301 includes an antenna 302, and includes an up / down converter 303 connected to the antenna inside, and information on the number of antennas of the communication destination terminal from a control signal connected to the up / down converter indicated by 304 and received. It comprises a reading and holding portion and a portion indicated by 305 that generates a transmission signal for each terminal based on the information of 304.

  The wireless terminal B 306 includes two antennas, a first antenna 307 and a second antenna 308, and includes a first up / down converter 309 connected to the first antenna 307 and the second antenna. A second up / down converter 310 connected to 308 is provided. Further, the two up / down converters 309 and 310 are further connected to a part for transmitting a control signal indicated by 311 and a receiving part 312.

  Similarly, the wireless terminal C313 includes three antennas, a first antenna 314, a second antenna 315, and a third antenna 316, and a first up / down converter connected to the first antenna 314 inside. 317, a second up / down converter 318 connected to the second antenna 315, and a third up / down converter 319 connected to the third antenna 316. Further, the three up / down converters 317, 318, and 319 are connected to a part for transmitting a control signal indicated by 320 and a receiving part 321.

  In FIG. 2, reference numeral 3001 denotes a frame configuration of a transmission signal for radio terminal B 306 according to Embodiment 3 of the present invention, and 3002 denotes a frame configuration of a transmission signal to radio terminal C 313. Further, 3003 indicates a part of the control signal transmitted by the wireless terminal B 306, and similarly 3004 indicates a part of the control signal transmitted by the wireless terminal C 313. Hereinafter, the operation of each wireless terminal according to Embodiment 3 of the present invention will be described with reference to FIG.

  First, at a time before the wireless terminal A301 transmits data, the wireless terminal B306 transmits a control signal 311 to the wireless terminal A301. This control signal includes information indicating that the number of antennas included in the wireless terminal B 306 is 2, as indicated by 3003. When the wireless terminal A301 receives the control signal from the wireless terminal B306, a portion indicated by 304 in the wireless terminal A reads that the number of antennas of the wireless terminal B is 2, and holds this information. Similarly, this time, the wireless terminal C 313 transmits a control signal 320 to the wireless terminal A 301. This control signal includes information indicating that the number of antennas included in the wireless terminal C313 is 3, as indicated by 3004. When the wireless terminal A301 receives the control signal from the wireless terminal C313, the portion indicated by 304 in the wireless terminal A reads that the number of antennas of the wireless terminal C is 3, and the information on the number of antennas of the wireless terminal B is described above. At the same time, it holds the number of antennas information of the wireless terminal C.

  Next, when the wireless terminal A301 transmits data to the wireless terminal B306, the number of training symbols as indicated by 3001 is 2 from the information on the number of antennas of the wireless terminal B held in 304 as a transmission signal of 305. A transmission frame is generated and transmitted. Similarly, when the wireless terminal A301 transmits data to the wireless terminal C313, the number of training symbols as indicated by 3002 is 3 from the information on the number of antennas of the wireless terminal C held in 304 as a transmission signal of 305. A transmission frame is generated and transmitted.

  By doing so, when the wireless terminal B 306 receives the wireless signal, the internal receiving unit 312 can perform the adaptive array combining calculation in the first embodiment, and the wireless terminal C 313 receives the wireless signal. In this case, the internal receiving unit 321 can perform the adaptive array combining operation in the second embodiment.

  Therefore, according to such a configuration, information including the number of antennas of each wireless terminal is transmitted to the inside of the control signal in a time before data transmission, and the wireless terminal that performs data transmission receives information on the number of antennas of each counterpart wireless terminal. , And generating and transmitting a transmission frame including training symbols equal to the number of antennas to each terminal, it is possible to realize adaptive array combining with a small amount of computation at all times.

(Embodiment 4)
FIG. 4 is a flowchart showing the configuration and operation of the radio reception apparatus according to Embodiment 4 of the present invention.

  In FIG. 4, reference numeral 401 denotes a wireless reception device, which includes a first antenna indicated by 402 and a second antenna indicated by 403. The respective antennas are connected to a first down converter indicated by 404 and a second down converter indicated by 405, respectively. Further, each of the down converters is connected to the reception circuit selection unit 406. The receiving circuit selection unit 406 outputs the received signal input according to the control signal to the adaptive array combining unit indicated by 407 or the maximum power ratio combining unit indicated by 408. Further, the output of the adaptive array combining unit 407 and the output of the maximum power ratio combining unit 408 are connected to a reception signal selection unit 409. The reception signal selection unit 409 receives two inputs based on a control signal. One is selected and output to the demodulator 410. Further, the signal demodulated by the demodulator 410 is output to the decoder 411 for decoding. The decoded data is output to an error rate measurement unit 412. The error rate measurement unit 412 calculates a frame error rate per unit time. When the error rate exceeds a predetermined threshold value, a control signal for combining method switching is output. Output. The control signal for switching the synthesis method is connected to the reception circuit selection unit 406 and the reception signal selection unit 409. The adaptive array combining unit 407 shown here is provided with the receiving method shown in the first embodiment. The maximum specific power combining unit 408 combines the signals received from the two antennas so that the ratio between the signal power and the noise power is maximized.

  Also, in FIG. 4, reference numeral 4001 is a flowchart briefly showing the operation of the radio reception apparatus according to the fourth embodiment of the present invention. Hereinafter, the operation of the radio reception apparatus according to Embodiment 4 of the present invention will be described with reference to FIG. Here, description will be made assuming that the threshold value of the set error rate is 10%.

  As indicated by reference numeral 4001 in FIG. 4, the radio reception apparatus according to the present embodiment performs reception processing by adaptive array synthesis and demodulates the received signal. The demodulated received signal is decoded and an error rate measuring unit 412 detects an error for each received frame, and calculates a frame error rate at regular intervals. If this error rate is within 10%, reception by adaptive array synthesis is continued. However, when the frame error rate exceeds 10% in the error rate measuring unit 412, a control signal for combining method switching is output, and the reception circuit selection unit 406 and the reception signal selection unit 409 receive the signal and perform reception processing. Switch from adaptive array synthesis to maximum power ratio synthesis.

  Similarly, after the received signal demodulated by the maximum specific power combining is decoded, an error rate measurement unit 412 detects an error for each received frame, and calculates a frame error rate at regular intervals. When this error rate is within 10%, reception by maximum specific power combining is continued. However, when the frame error rate exceeds 10% in the error rate measurement unit 412, a control signal for combining method switching is output, and the reception circuit selection unit 406 and the reception signal selection unit 409 again perform reception processing with maximum specific power combining. To receive by adaptive array synthesis. Thereafter, the above operation is repeated every time the frame error rate exceeds 10%.

  The reception method by adaptive array synthesis in the present invention is a useful reception means because a reception signal in which interference waves are suppressed can be obtained in the presence of interference waves, but unnecessary signals that do not have directivity such as Gaussian noise. Therefore, maximum specific power combining is a more effective reception method.

  Therefore, according to such a configuration, the error rate of the decoded received signal is calculated, and when the set threshold value is exceeded, the function of receiving by switching the receiving means between the adaptive array combining method and the maximum power ratio combining method is provided. As a result, it is possible to realize a radio receiving apparatus that can maintain a certain communication quality against interference waves and Gaussian noise.

  The wireless communication apparatus according to the present invention has adaptive array combining means at the receiving station, can perform highly reliable communication even in an environment where an interference signal exists, and is useful as a wireless LAN apparatus or the like. It can also be applied to in-home wireless network devices that connect a plurality of home appliances and the like wirelessly.

Configuration diagram of radio communication apparatus according to Embodiment 1 of the present invention Configuration diagram of radio communication apparatus according to Embodiment 2 of the present invention The figure which shows the structure of the radio | wireless communication apparatus in Embodiment 3 of this invention, and the structure of the packet transmitted / received. The flowchart which shows the structure and operation | movement of a radio | wireless receiver in Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Radio transmission apparatus 102 Transmission signal 103 Up converter 104 Transmission station antenna 105 Radio reception apparatus 106 Reception station 1st antenna 107 Reception station 2nd antenna 108 1st down converter 109 2nd down converter 110 Transmission signal estimation part 111 Transmission path estimator 112 Received signal synthesizer 113 Transmission signal estimated value 1001 after synthesis 1001 Signal frame in transmission signal 102 1002 Signal frame after first downconverter 108 1003 Signal frame after second downconverter 109 1004 Reception Signal frame after signal combination 201 Wireless receiver 202 Reception station first antenna 203 Reception station second antenna 204 Reception station third antenna 205 First down converter 206 Second down converter 207 3 Downconverter 208 Transmission signal estimation unit 209 Transmission path estimation unit 210 Reception signal synthesis unit 211 Transmission signal estimated value after synthesis 2001 Signal frame in transmission signal generation unit 102 2002 Signal frame after passing through first down converter 108 2003 2 Signal frame after passing through down converter 109 2004 Signal frame after passing through third down converter 109 2005 Signal frame after combining received signal 301 Wireless terminal A
302 Antenna of wireless terminal A 303 Up / down converter of wireless terminal A 304 Number of antennas information for each partner terminal 305 Transmission signal of wireless terminal A 306 Wireless terminal B
307 Radio terminal B first antenna 308 Radio terminal B second antenna 309 Radio terminal B first up / down converter 310 Radio terminal B second up / down converter 311 Radio terminal B control signal 312 Reception unit 313 of wireless terminal B Wireless terminal C
314 Radio terminal C first antenna 315 Radio terminal C second antenna 316 Radio terminal C third antenna 317 Radio terminal C first up / down converter 318 Radio terminal C second up / down Converter 319 Third up / down converter of radio terminal C 320 Control signal of radio terminal C 321 Reception unit of radio terminal C 3001 Transmission signal frame for radio terminal B in radio terminal A 3002 To radio terminal C in radio terminal A Transmitted signal frame 3003 Part of control signal frame at wireless terminal B 3004 Part of control signal frame at wireless terminal C 401 Wireless receiver 402 First antenna 403 Second antenna 404 First down converter 405 Second Down converter 406 Receiver circuit selector 4 7 flow chart showing the operation of the adaptive array combining section 408 the maximum power ratio combining section 409 receives the signal selecting unit 410 demodulation unit 411 decoding unit 412 the error rate measuring unit 4001 radio receiver

Claims (3)

Multiple antennas,
Transmission composed of a transmission path estimation unit that estimates a transmission path from training signals received from the plurality of antennas and obtains a weight vector for combining, and a received signal combining section that combines received signals based on the weight vector Signal estimation means;
A wireless communication method comprising transmission means for transmitting a signal having a plurality of training signals t equal to the number of antennas of a receiving station at the head of a transmission frame,
The received training signal is a square matrix r,
A wireless communication method for obtaining the weight vector by W = t / r. Characterized in that the receiving station includes information on the number of antennas included in the control signal included in the control signal, and transmits it.
The transmitting station receives the control signal, and generates and transmits a training signal equal to the number of antennas to the receiving station in a transmission signal format.
The wireless communication method according to claim 1. First receiving means for combining received signals based on weight vectors;
A second receiving means for performing maximum power ratio combining;
Means for switching the first or second receiving means;
An error rate measuring unit that calculates an error rate of received data and selects either the first or second receiving means from the result,
A wireless reception device that switches the reception unit according to a reception situation.

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