JP2007124412A - Radio communication apparatus and signal processing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to deem that a radio wave propagation path is always equal in transmission and in reception. <P>SOLUTION: A radio communication apparatus 30 has a transmitter 10b for transmitting a transmission signal using a transmission antenna 20, and a receiver 10a for receiving a reception signal using a reception antenna 11. The receiver has a delay tap coefficient estimator 13 for obtaining a delay tap coefficient on the basis of the reception signal, a reception equalizer 14 for equalizing the reception signal according to the delay tap coefficient to acquire a reception equalization signal, and a time-series amplitude phase corrector 15 for correcting the reception equalization signal in response to the amplitude phase characteristics of the reception equalization signal. The transmitter has a transmission equalizer 32 for performing equalization processing for the transmission input signal according to the time-series delay tap coefficient. A time-series delay tap coefficient estimator 31 generates a time-series tap based on the delay tap coefficient and on the amplitude phase characteristics, and provides the generated tap to the transmission equalizer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs communication while reducing the effects of intersymbol interference and interference waves, and a signal processing method therefor.

  In general, as a wireless communication device, an interference wave (interference wave) having the same frequency (channel) as a desired wave, that is, the same channel interference is removed, and the desired wave is temporally processed by signal processing on the time axis. There is known a method in which delayed waves are removed, that is, intersymbol interference is removed. FIG. 5 is a block diagram showing a conventional wireless communication apparatus. In FIG. 5, the wireless communication apparatus 10 includes a receiver unit 10a and a transmitter unit 10b. Are provided with a demodulator 12, a delay tap coefficient estimator 13, a reception equalizer 14, a time series amplitude phase corrector 15, and a decoder 16. On the other hand, the transmitter unit 10 b includes an encoder 17, a transmission equalizer 18, a modulator 19, and a transmission antenna 20.

  In the illustrated wireless communication apparatus 10, the received signal received by the receiving antenna 11 is demodulated by the demodulator 12 and provided to the delay tap coefficient estimation unit 13 and the reception equalizer 14 as a demodulated signal (baseband signal). . Then, the delay tap coefficient estimation unit 13 obtains a delay tap coefficient according to the demodulated signal, and gives this delay tap coefficient to the reception equalizer 14. The reception equalizer 14 equalizes the demodulated signal with the delay tap coefficient and supplies it to the time-series amplitude phase corrector 15 as a reception equalized signal.

  Here, in the radio wave propagation path, intersymbol interference inevitably occurs due to multipath fading and the like and is affected by the interference wave. In the delay tap coefficient estimation unit 13, for example, a known reference signal (training signal) and a demodulated signal are detected. (That is, the delay tap coefficient is estimated in accordance with the correlation with the received signal), and the reception equalizer 14 sequentially accumulates the delay tap coefficient to perform equalization processing to obtain a demodulated signal, that is, the received signal. The intersymbol interference and interference wave are removed.

  The time-series amplitude / phase corrector 15 linearly changes the amplitude / phase, which changes every moment due to the influence of the radio wave propagation path, based on the correlation between the received equalization signal (that is, the received signal) and the training signal. ) And the amount of change is added as a correction amount to the reception equalized signal to reduce reception errors. The output (amplitude corrected signal) of the time series amplitude phase corrector 15 is given to the decoder 16, where it is decoded and output as a received data string.

  In the transmitter unit 10b, the transmission data string is given to the encoder 17, where it is encoded to be an encoded signal. Then, the encoded signal is given to the transmission equalizer 18. The transmission equalizer 18 has the same number of delay taps as the reception equalizer 14, performs an equalization process by performing an inner product on the encoded signal with the delay tap coefficient given from the delay tap coefficient estimation unit 13, transmission, etc. The modulated signal is supplied to the modulator 19, and the modulator 19 modulates the transmission equalized signal and transmits it as a transmission signal from the transmission antenna 20.

On the other hand, a receiver obtains a weighting factor by a delay circuit, and an interference canceling circuit removes an interference wave from a transmission signal (that is, a received signal) transmitted from the transmitter according to the weighting factor. Yes (see Patent Document 1).
JP-A-9-51320 (pages 4 to 7, FIGS. 1 to 4).

  By the way, when the wireless communication device is mounted on a mobile station such as a vehicle and wireless communication is performed between the mobile station and the base station, if the mobile station moves at high speed, the environment of the radio wave propagation path at the time of reception and transmission May change significantly. On the other hand, in the conventional wireless communication apparatus, since the equalization processing is performed by the transmission equalizer using the delay tap coefficient generated at the time of reception, the environment of the radio wave propagation path at the time of reception and at the time of transmission is If the radio wave propagation path does not change, the radio wave propagation path can be regarded as the same at the time of transmission and at the time of reception, but as described above, the radio wave at the time of reception and transmission such as when the mobile station moves at high speed. If the propagation path environment changes greatly, the radio wave propagation path cannot be regarded as equal between transmission and reception, and unnecessary interference due to the influence of the radio wave propagation environment occurs. A difference in signal reception error occurs between the transmission side and the transmission side. As a result, between wireless communication devices that communicate with each other, one wireless communication device can receive a transmission signal transmitted from the other wireless communication device, but the other wireless communication device has transmitted from one wireless communication device. There is a problem if it falls into a situation where a transmission signal cannot be received.

  An object of the present invention is to provide a radio communication apparatus and a signal processing method therefor that can always be regarded as being equal in radio wave propagation paths in transmission and reception.

  According to the present invention, in a wireless communication apparatus having a transmitter unit that transmits a transmission signal by a transmission antenna and a receiver unit that receives a reception signal by a reception antenna, the receiver unit equalizes the reception signal. A reception equalizing means for obtaining a reception equalized signal; and a correction means for correcting the received equalized signal according to the characteristics of the received equalized signal, wherein the transmitter section transmits input according to a transmission weighting factor. There is obtained a radio communication apparatus comprising transmission equalization means for equalizing a signal and transmission weight coefficient generation means for generating the transmission weight coefficient based on characteristics of the received equalization signal.

  The transmission weight coefficient generation means may include transmission characteristic prediction means for obtaining transmission characteristics based on a time difference between transmission and reception and characteristics of the reception equalized signal, and the transmission weights based on the transmission characteristics. A coefficient is generated.

  Further, the present invention is an array antenna in which each of the transmission antenna and the reception antenna has a plurality of antenna elements, and the reception equalization means equalizes the received signal for each antenna element and corresponds to the antenna element Antenna coefficient estimating means for obtaining a weighting factor for each received equalized signal as an antenna coefficient according to a plurality of the received equalized signals, and the antenna coefficient Detection means for multiplying the received equalized signal and multiplying the received equalized signal to synthesize the combined equalized signal.The correction means is provided with the synthesized equalized signal instead of the received equalized signal, The transmission weight coefficient generation means generates the transmission weight coefficient based on characteristics of the reception equalized signal and the antenna coefficient.

  The present invention is also a signal processing method used when transmitting a transmission signal using a transmission antenna and receiving a reception signal using a reception antenna, and obtains a reception equalization signal by equalizing the reception signal A reception equalization step, a correction step for correcting the reception equalization signal in accordance with the characteristics of the reception equalization signal, and a transmission weight coefficient generation step for generating the transmission weight coefficient based on the characteristics of the reception equalization signal; And a transmission equalization step for equalizing the transmission input signal in accordance with the transmission weighting factor.

  According to the present invention, the transmission weight coefficient generation step includes a transmission characteristic prediction step for obtaining a transmission characteristic based on a time difference between transmission and reception and a characteristic of the reception equalized signal, and the transmission weight coefficient based on the transmission characteristic. And generating.

  Further, the present invention is an array antenna in which each of the transmission antenna and the reception antenna has a plurality of antenna elements, and in the reception equalization step, the reception signals are equalized for each antenna element to correspond to the antenna elements. An antenna coefficient estimating step for obtaining a weighting coefficient for each received equalized signal as an antenna coefficient according to a plurality of the received equalized signals, and the antenna coefficient and the received equalized signal Each of the signals is multiplied and combined to obtain a combined reception equalized signal. In the transmission weight coefficient generation step, the transmission weight coefficient is determined based on the characteristics of the reception equalized signal and the antenna coefficient. Is generated.

  As described above, in the present invention, a transmission weight coefficient is generated based on the delay tap coefficient and the characteristics of the reception equalized signal, and the transmission input signal is equalized according to the transmission weight coefficient. The radio wave propagation path can be regarded as the same at the time of transmission and at the time of reception, causing unnecessary interference due to the influence of the radio wave propagation environment, and there is a difference in signal reception error between the reception side and the transmission side. There is an effect that it does not occur.

  In the present invention, since an array antenna having a plurality of antenna elements is used to generate a transmission weight coefficient based on the delay tap coefficient, amplitude phase characteristic, and antenna coefficient, an error during transmission and reception is further increased. There is an effect that it can be lowered.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a wireless communication apparatus 30 according to an embodiment of the present invention. In the wireless communication apparatus 30 shown in FIG. 1, the same components as those of the wireless communication apparatus 10 shown in FIG. Give a reference number.

  In FIG. 1, the wireless communication device 30 includes a receiver unit 10 a and a transmitter unit 10 b, and the transmitter unit 10 b newly includes a time-series delay tap coefficient estimation unit 31. The received signal received by the receiving antenna 11 is demodulated by the demodulator 12 and provided as a demodulated signal to the delay tap coefficient estimating unit (tap coefficient estimating means) 13 and the receiving equalizer (reception equalizing means) 14. The delay tap coefficient estimation unit 13 divides the demodulated signal (that is, the received signal) into time-series signal components and, for example, the least square error method represented by LMS (Least Mean Square) which is an adaptive algorithm. To obtain the delay tap coefficient.

  The reception equalizer 14 equalizes the demodulated signal with the delay tap coefficient. That is, the demodulated signal is subjected to a delay line filter to remove interference components (intersymbol interference and interference wave) to obtain a time-series amplitude as a received equalized signal. This is given to the phase corrector 15. The time-series amplitude phase corrector 15 determines the amplitude / phase {amplitude phase characteristic (also referred to as amplitude phase time coefficient) in the received equalized signal based on the correlation between the received equalized signal (that is, the received signal) and the training signal: The characteristics of the reception equalized signal} are predicted using, for example, a convolution operation, and the amount of change is used as a correction amount in addition to the reception equalized signal to reduce reception errors. Here, the convolution calculation performs the convolution calculation of the training signal and the reception signal in symbol units. In the convolved signal, the square root (the square of the real part + the square of the imaginary part) represents the amplitude, and arctan (the real part / imaginary part) represents the declination (phase). Note that when the amplitude or phase obtained here fluctuates in symbol units, the signal cannot be restored, so that the fluctuation of the amplitude or phase can be suppressed by multiplying the reception signal by the direction and reciprocal of the fluctuation. The output (amplitude corrected signal) of the time series amplitude phase corrector 15 is given to the decoder 16, where it is decoded and output as a received data string.

  As described above, in the transmitter unit 10b, the transmission data string is given to the encoder 17, where it is encoded to be an encoded signal (transmission input signal). Then, the encoded signal is given to a transmission equalizer (transmission equalization means) 32. Here, referring to FIG. 2, the transmission equalizer 32 includes first to Nth delay elements 33-1 to 33-N (where N is an integer equal to or greater than 2), and 0th to Nth multipliers 34. −0 to 34-N, and an adder 35 (N = 4 in the example shown in FIG. 2). Then, the encoded signal from the encoder 17 is supplied to the first delay element 33-1, and is delayed by a predetermined delay time τ to be a first delay signal. Similarly, the nth delay element 33-n receives the (n-1) th delay signal, delays the (n-1) th delay signal by a predetermined delay time τ, and outputs the nth delay signal. (Where n is any integer from 2 to N).

  A time series delay tap coefficient estimation unit (transmission weight coefficient generation means) 31 receives a delay tap coefficient from the delay tap coefficient estimation unit 13 and receives an amplitude phase coefficient (hereinafter, this amplitude phase time coefficient) from the time series amplitude phase corrector 15. (Referred to as “amplitude phase time coefficient”), outputs transmission time series delay tap coefficients (0th to Nth transmission time series delay tap coefficients) and outputs 0th to Nth multipliers as described later. 34-0 to 34-N. On the other hand, the encoded signal and the first to (N−1) th delayed signals are respectively supplied to the 0th to Nth multipliers 34-0 to 34-N, and the 0th to Nth multipliers 34−. In 0 to 34-N, the 0th to Nth multiplications are performed by multiplying the encoded signal and the 1st to (N-1) th delayed signals by the 0th to Nth transmission time series delay tap coefficients, respectively. The signal is supplied to the adder 35 as a signal. The adder 35 adds the 0th to Nth multiplication signals to obtain a transmission equalized signal.

FIG. 3 is a flowchart for explaining the operation of the time-series delay tap coefficient estimation unit.
Next, the operation of the time-series delay tap coefficient estimation unit will be described with reference to FIG.
The time series delay tap coefficient estimation unit 31 first holds the delay tap coefficient generated by the delay tap coefficient estimation unit 13 (holds the delay tap coefficient of the reception equalizer: step S1), and then performs time series amplitude phase correction. The reception amplitude phase time coefficient of the device 15 is held (step S2). Then, the time-series delay tap coefficient estimation unit 31 refers to the reception amplitude phase time coefficient and linearly predicts the amplitude phase time coefficient at the time of transmission according to the time difference between reception and transmission, thereby obtaining the transmission amplitude phase time coefficient. (Transmission characteristic predicting means: step S3).

  Subsequently, the time-series delay tap coefficient estimation unit 31 performs an inner product of the delay tap coefficient and the transmission amplitude phase time coefficient to obtain a time-series delay tap coefficient (transmission weight coefficient) (step S4). Thereafter, although not shown in FIG. 2, it is determined whether or not transmission data exists (transmission data = NULL) (step S5). If there is transmission data, the next sampling is performed (step S6). In the time series delay tap coefficient estimation unit 31, the process of step S4 is performed again. On the other hand, if the transmission data is NULL, the processing in the time-series delay tap coefficient estimation unit 31 ends.

  Referring again to the second example, the transmission equalization signal sent from the transmission equalizer 32 is given to the modulator 19 where it is modulated and transmitted from the transmission antenna 20 as a transmission signal.

  In this way, the transmission equalizer 32 integrates the encoded signal (and the delay signal) and the time-series delay tap coefficient for each delay tap (delay time τ is, for example, one symbol or less), The sum of the integration results with respect to the delay taps is taken, and the addition result is given to the modulator 19 as one symbol.

  Through the above processing, when a signal is multiplied and transmitted by a transmitter using a coefficient equalized in a receiver, a signal that becomes a channel equalization can be transmitted, and thereby a signal equalized toward a desired terminal Is transmitted, and errors during transmission can be reduced. Since the weighting coefficient of the transmission equalizer is obtained based on the delay tap coefficient and the reception phase amplitude time coefficient at the time of reception, the radio wave propagation path is always regarded as equal at the time of transmission and at the time of reception. be able to. In other words, even if the radio wave propagation environment changes frequently due to the high-speed movement of the mobile station, the radio wave propagation environment on the receiving side and the transmitting side can be accurately approximated. It is possible to sufficiently suppress the influence of

  Then, one wireless communication device can receive a transmission signal transmitted from the other wireless communication device, but the other wireless communication device reliably avoids a situation in which the transmission signal transmitted from one wireless communication device cannot be received. can do. As a result, data retransmission processing due to reception errors is reduced, which can contribute to effective use of frequencies.

  In FIG. 4, the receiving unit 10 a includes a receiving array antenna 41 having a plurality of antenna elements 41-1 to 41-K (K is an integer equal to or larger than 2 and K = 2 in the illustrated example), and a transmitting unit 10b is a block diagram illustrating an example of a wireless communication device 40 having a transmission array antenna 42 including a plurality of antenna elements 42-1 to 42-K. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 4 is a first diagram illustrating functional blocks of the wireless communication device.
Next, an example in which there are K antennas will be described with reference to FIG. In FIG. 4, a transmission signal transmitted from another wireless communication device (not shown, having the same configuration as that of the wireless communication device 40) is received as a reception signal by the reception array antenna 41, and the antenna element 41− The received signals from 1 to 41-K (K = 2 in the figure) are demodulated by the first to K-th demodulators 43-1 to 43-K, respectively, and the first to K-th demodulated signals respectively. The first to Kth delay tap coefficient estimators 44-1 to 44-K and the first to Kth reception equalizers 45-1 to 45-K are provided.

  The first to Kth delay tap coefficient estimators 44-1 to 44-K have the same configuration as the delay tap coefficient estimator 13 shown in FIG. 1, and the first to Kth receiver equalizers 45-1 to 45-1 to 45-K. 45-K has the same configuration as that of the reception equalizer 14, and the first to Kth delay tap coefficient estimation units 44-1 to 44-K respectively correspond to the first to Kth demodulated signals. First to Kth tap coefficients (each of which is a vector) are generated (estimated), and these first to Kth tap coefficients are supplied to the first to Kth reception equalizers 45-1 to 45-K. give. Then, the first to Kth reception equalizers 45-1 to 45-K equalize the first to Kth demodulated signals according to the first to Kth tap coefficients, respectively, to perform the first to Kth demodulation signals. Output as K reception equalization signal.

  An antenna coefficient estimator (antenna coefficient estimator) 46 generates an antenna coefficient (weight coefficient for each antenna element) weight coefficient W according to the first to Kth received equalized signals, and a detector (detector means) 47 For example, the antenna coefficient is multiplied by the first to Kth received equalization signals, and the multiplication outputs are combined (that is, detected) and output as a detection output signal. This detection output signal is given to the time-series amplitude phase corrector 15.

  The antenna time series delay tap coefficient estimation unit (transmission weight coefficient generation means) 48 is provided with the first to Kth delay tap coefficients, the antenna coefficient, and the reception amplitude phase time coefficient described above, and the antenna time series delay tap coefficient estimation. The unit 48 refers to the reception amplitude phase time coefficient and linearly predicts the amplitude phase time coefficient at the time of transmission according to the time difference between reception and transmission, thereby obtaining the transmission amplitude phase time coefficient. Then, the time series delay tap coefficient estimation unit 48 for each antenna obtains a transmission time series delay tap coefficient for each antenna element (transmission weight coefficient for each antenna) by inner product of the delay tap coefficient, the antenna coefficient, and the transmission amplitude phase time coefficient. .

  The transmission time-series delay tap coefficient for each antenna element is given to the transmission equalizer 49, and the transmission equalizer 49 is based on the encoded signal from the encoder 17 and the transmission time-series delay tap coefficient for each antenna element. Then, equalization processing similar to that of the transmission equalizer 32 is performed to obtain first to Kth transmission equalization signals corresponding to the antenna elements 41-1 to 41-K. The first to Kth transmission equalization signals are sent to the first to Kth modulators 50-1 to 50-K, respectively, where they are modulated to be antenna elements as the first to Kth transmission signals, respectively. 42-1 to 42-K. That is, a transmission signal is transmitted from the transmission array antenna 42.

  If an array antenna (adaptive array antenna) is used in this way, errors in transmission and reception can be further reduced. The processing in the above reception equalizer, detector, and transmission equalizer is not limited to the communication method and its algorithm, and the processing sequence in the reception equalizer, detector, and transmission equalizer is also limited. There is no limit. Then, equalization processing can be performed on any signal in the intermediate frequency band or the baseband band. Various methods can also be used for calculating the amplitude phase characteristic (characteristic of the received equivalent signal) in the time-series amplitude phase corrector.

  Furthermore, even when the received signal is not provided with a training signal, the time-series amplitude phase characteristic may be obtained using a so-called bride algorithm, and when using the bride algorithm, the amplitude is linear in time series and linearly. Rather than estimating the phase characteristic, the amplitude phase characteristic can be estimated nonlinearly.

  When transmitting a transmission signal, a transmission weighting factor is generated based on the delay tap coefficient and amplitude phase characteristic at the time of reception, and the transmission input signal is equalized according to the transmission weighting factor. As a result that the propagation path can always be regarded as equalization in transmission and reception, it can be applied to various wireless communication apparatuses.

It is a block diagram which shows an example of the radio | wireless communication apparatus by embodiment of this invention. It is a block diagram which shows the structure of the transmission equalizer shown in FIG. 3 is a flowchart for explaining an operation of a time-series delay tap coefficient estimation unit shown in FIG. 1. It is a block diagram which shows the other example of the radio | wireless communication apparatus by embodiment of this invention. It is a block diagram which shows the conventional radio | wireless communication apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,30 Wireless communication apparatus 10a Receiver part 10b Transmitter part 11 Receiving antenna 12, 43-1 to 43-K Demodulator 13, 44-1 to 44-K Delay tap coefficient estimation part 14, 45-1 to 45- K reception equalizer 15 time series amplitude phase corrector 16 decoder 17 encoder 18, 32, 49 transmission equalizer 19, 50-1 to 50-K modulator 20 transmission antenna 31 time series delay tap coefficient estimation unit 33 -1 to 33-N delay element 34-0 to 34-N multiplier 35 adder 41-1 to 41-K, 42-1 to 42-K antenna element 41 receiving array antenna 42 transmitting array antenna 46 antenna coefficient estimator 47 Detector 48 Antenna Time Series Delay Tap Coefficient Estimator

Claims (6)

In a wireless communication apparatus having a transmitter unit that transmits a transmission signal by a transmission antenna and a receiver unit that receives a reception signal by a reception antenna,
The receiver unit has reception equalization means for equalizing the reception signal to obtain a reception equalization signal, and correction means for correcting the reception equalization signal according to the characteristics of the reception equalization signal,
The transmitter unit equalizes a transmission input signal according to a transmission weight coefficient;
Transmission weight coefficient generation means for generating the transmission weight coefficient based on characteristics of the reception equalized signal;
A wireless communication apparatus comprising: The transmission weight coefficient generation means includes transmission characteristic prediction means for obtaining transmission characteristics based on a time difference between transmission and reception and characteristics of the reception equalized signal,
The radio communication apparatus according to claim 1, wherein the transmission weight coefficient is generated based on the transmission characteristics. The transmitting antenna and the receiving antenna are array antennas each having a plurality of antenna elements,
The reception equalization means equalizes the reception signal for each antenna element to obtain the number of reception equalization signals corresponding to the antenna element,
The receiver unit further multiplies the antenna coefficient estimating means for obtaining a weight coefficient for each received equalized signal as an antenna coefficient according to the plurality of received equalized signals, and the antenna coefficient and the received equalized signal, respectively. Detecting means for combining and making a combined equalized signal;
The correction means is provided with the synthesized equalized signal instead of the received equalized signal,
2. The radio communication apparatus according to claim 1, wherein the transmission weight coefficient generation unit generates the transmission weight coefficient based on characteristics of the reception equalized signal and the antenna coefficient. A signal processing method used when transmitting a transmission signal using a transmission antenna and receiving a reception signal using a reception antenna,
A reception equalization step of equalizing the reception signal to obtain a reception equalization signal;
A correction step for correcting the received equalized signal according to the characteristics of the received equalized signal;
A transmission weight coefficient generation step for generating the transmission weight coefficient based on characteristics of the received equalized signal;
And a transmission equalization step for equalizing the transmission input signal in accordance with the transmission weighting factor. The transmission weight coefficient generation step includes a transmission characteristic prediction step for obtaining a transmission characteristic based on a time difference between transmission and reception and a characteristic of the reception equalized signal;
The signal processing method according to claim 4, further comprising: generating the transmission weighting factor based on the transmission characteristics. The transmitting antenna and the receiving antenna are array antennas each having a plurality of antenna elements,
In the reception equalization step, the reception signal is equalized for each antenna element to obtain the number of reception equalization signals corresponding to the antenna element,
Further, an antenna coefficient estimation step for obtaining a weight coefficient for each reception equalized signal as an antenna coefficient in accordance with a plurality of the reception equalized signals;
A detection step of multiplying the antenna coefficient and the reception equalized signal, respectively, and combining them to obtain a combined received equalized signal;
5. The signal processing method according to claim 4, wherein, in the transmission weight coefficient generation step, the transmission weight coefficient is generated based on characteristics of the reception equalized signal and the antenna coefficient.

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