JP2000091844A - Multiplex radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quality of bi-directional communication of plural information without damaging the cost performance of a terminal station by providing a directivity calculating means, etc., which obtains antenna directivity suppressing unnecessary waves excepting each direct wave and multiplexes the antenna directivity of these. SOLUTION: A digital signal processor(DSP) 106 executes PDA analysis by spectrum analyzing technique by using the received digital signal of each system. A CPU 107 calculates a beam peak in the direction of the direct wave of a desired wave and a weight which forms null in the unnecessary wave direction excepting it by each terminal based on this PDA analyzing result. An arithmetic circuit 109 obtains the product sum of the weight and each received signal to output multiplexed information R1 to RM. An arithmetic circuit 108 generates a multiplexed signal to supply for each system of an antenna from the matrix product of plural transmitting digital signals T1 to TM to multiplex and a weight matrix. Thus, it is possible to execute communication which interference between terminal stations and signal removal of a multipath is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex radio communication apparatus, and more particularly to a space division multiple access in a mobile communication system.
The present invention relates to a multiplex wireless communication apparatus of a base station used for eAccess (SDMA).

[0002]

2. Description of the Related Art Recent mobile phones, PHS (Person)
The development of mobile communication systems such as Al Handyphone System) has been remarkable, and connections to data communication such as e-mail and the Internet have begun in addition to voice information. It is expected to do. SDMA has attracted attention as a technique for effectively using frequency resources.

In the SDMA system, an information transmission space is divided and different information transmissions are performed at the same time and in the same frequency band for each of the divided spaces.
When combined with other multiplexing methods such as TDMA and CDMA, the transmission capacity can be dramatically increased.

[0004] To implement SDMA, the direction of arrival (DOA: Dir) of an access signal from a terminal station at a base station is considered.
function to measure the signal of other stations and the function to form an adaptive beam pattern for removing multipath waves that cause data errors in high-speed digital communication in transmission and reception. Therefore, a function of a multi-beam antenna for multiplexing adaptive beams is required.

Also, in order to recognize a multipath wave, an arrival delay time (TOA: Time of A) of an access signal is required.
Rival) is also required.

[0006] Among these functions, the concept of the device excluding the functions of the transmission adaptive beam forming and the multi-beam antenna is referred to as "Smart Antenna" as "Dir."
Edition Finding and Smart
Antennas Using Software R
audio Architectures ”, IEEE
communications Magazine, May
1995, pp. 62-68 (Reference 1).

Further, the DOA of the terminal station is estimated at the terminal station by rotational scanning of the fan beam of the base station, the result is notified to the base station, and the peak of the fan beam is directed to the azimuth of the terminal station to perform interference cancellation. The method is described in JP-A-8-8814 (Document 2). Further, the base station performs beam scanning on the high and low planes and performs CIR (Carrier Intefe).
Japanese Patent Application Laid-Open No. Hei 4-1992 proposes a method of obtaining a beam scanning angle at which the maximum (Radence Radio) is obtained and scanning the beam in that direction.
No. 320122 (Document 3).

[0008]

In any of the above-mentioned techniques, the function of a multi-beam antenna for multiplexing adaptive beams is lacking, so that there is a drawback that it cannot cope with a large number of terminal stations. Further, in the technique of Reference 1, the transmission antenna pattern of the base station is not adaptively beamformed, and thus the multipath wave is received together with the direct wave at the terminal station, so that the quality of the received signal at the terminal station is degraded. There is a disadvantage that.

In Documents 2 and 3, the DOA of the terminal station is obtained by fan beam scanning.
The estimation error is large, it is difficult to accurately direct the main beam to the target terminal station, and the DOA of the unnecessary wave does not always hit the null of the fan beam, but only the suppression ratio of the average sidelobe level. Since it cannot be expected, there is a disadvantage that suppression of unnecessary waves is limited.

[0010] These problems can be solved to some extent by increasing the antenna size of the base station. However, problems such as deterioration of economy, increase in DOA estimation time due to terminal station search, and lack of detection are caused. Will do.

[0011] In Document 2, it is necessary to transmit the DOA estimation result of the own station estimated by the terminal station to the base station, so that additional data communication is newly generated and effective use of radio waves is required. There is also the problem of going backwards. Since the base station rotates and scans the fan beam, it is necessary to continuously transmit at least one cycle of scanning, and the terminal station requires a DOA estimating function, which has the disadvantage of being expensive. .

It is an object of the present invention to divide a space into two parts at the same time,
In the same frequency band, two-way communication of a plurality of information was enabled, and high-quality communication with interference between terminal stations and multipath signal removal was made possible without impairing the economic efficiency of the terminal stations. A multiplex wireless communication device is provided.

[0013]

According to the present invention, there is provided a multiplex wireless communication apparatus as a base station for performing wireless communication with a plurality of terminal stations, comprising: an array antenna comprising a plurality of antenna elements; A plurality of transmission / reception module means for demodulating a multiplexed reception signal provided for each of the antenna elements and converting the multiplexed transmission signal into a signal in a communication frequency band, and demodulation by the plurality of transmission / reception modules; First computing means for analyzing the direction of arrival, delay time, and relative power of each received signal, and the direction of arrival of direct waves for the terminal station based on the direction of arrival, delay time, and relative power of each of the received signals. And a directivity calculation means for obtaining an antenna directivity for suppressing unnecessary waves other than each of the direct waves and multiplexing these antenna directivities. Multiplex radio communication apparatus according to claim is obtained.

Further, according to the present invention, there is provided a multiplex radio communication apparatus as a base station for performing radio communication with a plurality of terminal stations, comprising: an array antenna including a plurality of antenna elements; A plurality of transmitting and receiving module means for demodulating a multiplexed received signal provided in correspondence with and converting a transmission signal into a signal in a communication frequency band,
Analysis means for analyzing the direction of arrival, delay time, and relative power of each received signal demodulated by the plurality of transmitting / receiving modules; and adaptive multiplexing based on the direction of arrival, delay time, and relative power of each of the received signals. Means for obtaining a weight matrix for forming a pattern; means for performing a matrix operation of the weight matrix and the transmission signal to supply a multiplexed baseband transmission signal to the transmission / reception module means; and Means for outputting a product sum with a demodulated signal from said transmitting / receiving module means.

The operation of the present invention will be described. Calculating means for calculating a weight matrix forming a multiplexed adaptive pattern, calculating means for extracting each of the multiplexed received signals using the weight matrix, and using the weight matrix The provision of the arithmetic means for multiplexing a plurality of transmission signals makes it possible to support a large number of terminal stations.

PDA (Power Delay Amp)
While the gain in the desired wave direction is secured based on the analysis of the antenna, the antenna directivity in the unnecessary wave direction is null.
The optimum antenna directivity is realized in both transmission and reception by obtaining an adaptive weight forming l). Therefore, unnecessary wave signals can be sufficiently suppressed, and good communication quality can be obtained in both the base station and the terminal station.

The PDA analysis is performed by a spectrum analysis technique without using the fan beam scanning. The PDA analysis based on the spectrum analysis can obtain high accuracy with a relatively small antenna array, and is excellent in economy. Also, it does not require time for searching for a terminal station by beam scanning,
There is no possibility of missing detection.

Since the PDA analysis is performed only by the base station, there is no need to specify the DOA in the terminal station and to notify the base station of the result, which enables effective use of radio waves and impairs the economic efficiency of the terminal station. There is no.

[0019]

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

FIG. 1 is a block diagram showing an embodiment of the present invention. Referring to FIG. 1, in the preferred embodiment of the base station of the present invention, an array antenna in which a plurality of antenna elements 101 are arranged on a circumference is provided, and a communication frequency received by these antenna elements 101 is provided. Has a function of demodulating the signals X1 to XN of the band, further converting the signals into digital signals and outputting the digital signals, and a function of converting the multiplexed transmission digital signals into a communication frequency band and transmitting the signals to the antenna element; A TR module 102 is provided in one-to-one correspondence with the antenna element.

DSP (Digital Signal Processor) 1
Reference numeral 06 performs a PDA analysis by using a received digital signal of each system by a spectrum analysis technique such as a super-resolution technique. C
The PU 107 calculates a weight for forming a beam peak in a direct wave direction of a desired wave and a null for forming a null in other unnecessary wave directions for each terminal based on the PDA analysis result. Arithmetic circuit 1
09 outputs the multiplexing information R1 to RM by calculating the product sum of the weight and each received signal.

The arithmetic circuit 108 generates a multiplexed signal to be supplied to each antenna system from a matrix product of a plurality of multiplexed transmission digital signals T1 to TM and a weight matrix. The local oscillator 103 is used to convert a radio frequency band signal received by each antenna element 101 into a baseband signal.

The multiplexed transmission digital signal is converted into an analog baseband signal by the TR module 102, and the carrier generator 104 converts the signal into a radio frequency band signal, and performs PDA analysis and adaptive pattern formation. Is used for generating a calibration signal for measuring a phase and amplitude difference between channels of the TR module.

Next, the operation of the embodiment of the present invention will be described in detail. First, the case where the access signal from the terminal station is received by the base station will be described.

In an urban environment, a multipath propagation wave is received by the antenna array in addition to a direct wave. Generally, phase modulation (PSK) is used in mobile communication. However, if a multipath propagation wave and a direct wave are received simultaneously, correct information cannot be demodulated due to interference as shown in FIG.

For this reason, as shown by the solid line in FIG. 3, it is necessary to form an antenna directivity that takes out only the direct wave and suppresses the multipath wave. When a plurality of terminal stations exist in the communication area, it is necessary to form a multiplexed antenna directivity for extracting only direct waves for each terminal station.

CMA (Constant Modulus A) is a means for obtaining optimum directivity for only one oscillation source.
lgorithm) Adaptive antennas are known, but cannot cope with a plurality of oscillation sources.
Therefore, DOA and TOA of the signal arriving at the antenna are measured, and the azimuth / delay / power (PD) of the arriving wave as shown in FIG.
A: Power Delay Angle) profile is measured.

Since the direct wave propagates through the shortest path, the delay time is short and the relative power is large. Therefore, the direct wave can be distinguished from the multipath propagated wave from the PDA profile.

As methods for obtaining DOA and TOA, Fourier transform method, MUSIC (Multiple Signal)
l Classification), ESPRIT
(Estimate of Signal Param
eters via Rotary Inva
A spectrum analysis technique using a super-resolution algorithm such as R.I.R.Techniques is used. The Fourier transform method is described in the document “High-Resol.
union Analysis of Indoor
Multipath Propagation Str
result: ICIEC Trans. Vol E7
8-B, No. 11, 1995 pp1450-7 ",
For the MUSIC method, refer to the document "Estimation of propagation delay time and direction of arrival of quasi-millimeter wave band indoor multiplex wave using regular triangle array by FET-MUSIC method; Shinei Giho, AP95-1
20, 1996 ", and the document" H
high-Resolution 3-D Direct
ion of Arrival Determinat
ion for Urban Mobile Radi
o: IEEE Trans. APVol 45 (4) 1
997 ". The DSP 106 obtains a PDA profile by these methods.

FIG. 5 is a flowchart of the DSP 106 for obtaining the PDA profile.

The received signal received by each antenna element (S200) is demodulated to extract the terminal ID code (S201). After PSK-modulating the time-series ID code (S203), FET processing is performed (S204), a reference signal in the frequency domain is obtained, and N-channel received signals are also subjected to FET processing for each demodulated signal (S20).
2), transform into the frequency domain and divide by the corresponding reference signal (S205).

The M signals divided by the reference signal are sampled at predetermined frequency intervals to form N M × M correlation matrices (S206). In order to improve the delay time estimation accuracy, the N correlation matrices are simply added (S207).

Moving average processing is performed to analyze correlated wave sources (S208). The correlation matrix obtained by moving average is decomposed into eigenvalues (S209), and the number of wave sources is estimated from the magnitude of the eigenvalues (S210). The eigenvector corresponding to the minimum eigenvalue is obtained, and the delay time is estimated by obtaining the next MUSIC spectrum PMU (S21).
1).

[0034]

(Equation 1)

Next, a correlation matrix between received signals of each channel (channel) (in the frequency domain divided by the reference signal) is obtained (S212), and a moving average is performed (S213).
A signal power matrix is obtained by an inverse matrix operation from the array manifold created based on the delay time obtained earlier (S21
4) Relative power based on the amplitude of the diagonal component of the signal power matrix,
The arrival direction is obtained from the phase value (S215).

The CPU 107 calculates a weight for providing directivity for extracting a signal coming from only one direction based on the PDA profile. Here, since the arrival direction is known, the weight is obtained by the Howell-Applebaum algorithm. Howell-Apple
The weight calculation method using the baum algorithm is described in the document "A
Adaptive Arrays: IEEE Tran
s. Vol. AP-24 (5), pp585-598,
1976 ". Among the signal groups determined to be output from the same wave source, the one having a short delay time and a high relative power is determined to be a direct wave, and the adaptive weight is calculated. Send to

The arithmetic circuit 109 calculates the product sum of the received signals X1 to XN of the respective TR modules and the calculated adaptive weights and outputs the result.

The multiplexing of the transmission signal is performed by transmitting the transmission information from T1 to T1.
When TM is set, it can be realized by the following equation (2).

[0039]

(Equation 2)

X1,..., XN are multiplexed signals supplied to each antenna element.

The arithmetic circuit 108 performs the arithmetic operation of equation (2) and supplies the multiplexed transmission digital signal to the TR module.

TR module 102, local oscillator 10
3. The operation of the carrier oscillator 104 will be described in detail with reference to FIG.

The signal received by the antenna element 101 passes through the circulator 201,
Connected to two terminals. In the case of reception, the signal is sent to the low noise amplifier (LNA) 203 as shown in the connection of FIG. The signal amplified by the amplifier 203 is mixed with the output signal of the local oscillator by the mixer 204 and frequency-converted.

The frequency-converted signal is applied to the bandpass filter 20.
After the high frequency component is removed by the IQ detector 5, the IQ detector 20
The signal is orthogonally detected at 6 and converted to a digital signal at the A / D converter 207. The received signal converted into the digital signal is detected by each of the plurality of decoders 208 to detect the ID code of each terminal, multiplexed again by the multiplexer 209, and output to the DSP 106 and the arithmetic circuit 109.

The transmission signal multiplexed by the arithmetic circuit 108 is converted by a D / A converter 210 into an analog signal. The switch 212 supplies the output of the carrier generator 104 to a mixer 211 for converting a baseband multiplexed transmission signal into a communication frequency band, or a calibration signal switch for use in calibrating the relative amplitude and phase of a transmission / reception system. Switching between connection to the input terminal 202 is performed. When used for calibration of the transmission system, it is connected to the mixer 211 as shown in FIG.

The transmission signal converted into the communication frequency band is
Unnecessary frequency components are removed by the bandpass filter 213, amplified to a predetermined output by the power amplifier 214, and supplied to the antenna element 101 via the circulator 201. The coupler 212 is provided for extracting a signal for calibrating the transmission system, and the other one of the calibration signal switch 202 is provided.
Connected to terminal.

Calibration is performed between the amplitudes of the TR module channels,
The phase deviation is obtained, the received signal used for the PDA analysis is corrected, and the weight for forming the directivity is corrected. Assuming that the complex received signal after A / D conversion is X and the relative amplitude and phase of the system are A and φ, the complex received signal Y after calibration is given by the following equation (3).

[0048]

(Equation 3)

Similarly, the weight after calibration is given by the following equation (4).

[0050]

(Equation 4)

W is the weight before calibration, and Z is the weight after calibration.

In the calibration of the received signal, the output of the carrier generator 104 is used as a switch 212 and a calibration signal switch 20.
2 is connected to the amplifier 203. In the calibration of the transmission signal, the mixer 211, the bandpass filter 213, the power amplifier 214, the coupler 215, the calibration signal switch 202
Is connected to the amplifier 203 via the.

When calibrating the transmission signal, it is necessary to consider the relative amplitude and phase of the receiving system. That is, assuming that the measurement results of the relative amplitude and phase of the transmission system are AT and φT and the measurement results of the relative amplitude and phase of the reception system are AR and φR, the following coefficients are used in forming the transmission directivity.

[0054]

(Equation 5)

Next, a second embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 7, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the second embodiment of the base station of the present invention will be described.
In this embodiment, a system for performing PDA analysis and a system for performing SDMA are separated.

Generally, in the PDA analysis, a high resolution can be obtained even with a relatively small antenna by a spectrum analysis technique. However, in order to provide narrow beam transmission and reception directivity in SDMA, an antenna having a large aperture is required. When the received signals of a large number of TR modules are handled in the PDA analysis, the resolution becomes higher, but the calculation load increases exponentially.

Therefore, a PDA with a relatively small antenna
Analysis is performed and directivity is formed with a large-scale antenna. Antenna element 301 is identical to antenna element 101, but arranged in a smaller aperture. Antenna element 3
A receiving module 302 arranged one-to-one with an antenna element 301 having a function of demodulating a signal of a communication frequency band received at 01 is separately configured for PDA analysis. Further, a switch 30 for switching and inputting a calibration signal to measure the relative amplitude and phase of the receiving module 302
Three have been added.

FIG. 8 is a block diagram showing the configuration of the receiving module. The configuration of a calibration signal switch 303 for switching and inputting the received signal of the antenna element 301 and the calibration signal is different, and the receiving system of the TR module 102 is different. Is the same as

[0059]

A first advantage is that a base station which forms a multiplexed transmission and reception adaptation pattern can be provided. As a result, a large number of terminal stations can be handled. The reason is that the DOA and TOA of the signal arriving at the base station are recognized by the PDA analysis, the DOAs of the direct waves from a plurality of terminal stations are obtained using the TOA, the direct waves of each terminal station are stored, and other unnecessary waves are saved. This is because a plurality of adaptive patterns for suppressing waves can be multiplexed and given.

The second effect is that an optimum antenna directivity is realized in transmission and reception. Thereby, good communication quality can be given to both the base station and the terminal station. The reason is that both transmission and reception systems have D
This is because a BF (Digital Beam Forming) circuit is provided, and adaptive directivity is formed in transmission and reception by adaptive weights obtained by PDA analysis.

A third effect is that a highly accurate PDA analysis result can be obtained with a small antenna. Therefore, the size of the base station antenna can be reduced, which is economically advantageous. The reason is that spectrum analysis technology
This is because the analysis is being performed. Since fan beam scanning is not required, there is also an effect of shortening a search time and preventing a terminal station from being lost.

The fourth effect is that the terminal station does not need to perform the DOA estimation and the base station notification. For this reason, it is not necessary to add a new function to the terminal station, and it is possible to reduce the size of the terminal station, realize high economic efficiency, and realize effective use of frequency resources.
The reason is that the PDA analysis is performed only by the base station.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a base station according to the present invention.

FIG. 2 is an explanatory diagram illustrating an influence of a multipath signal on a PSK modulation signal.

FIG. 3 is a conceptual diagram illustrating multiplexed adaptive directivity.

FIG. 4 is a graph showing an example of PDA analysis.

FIG. 5 shows the operation of the DSP 106, which is an FFT-M.
It is a flowchart of a USIC method.

FIG. 6 is a block diagram showing one embodiment of a TR module.

FIG. 7 is a block diagram showing another embodiment of the present invention.

FIG. 8 is a block diagram of a receiving module used in another embodiment of the present invention.

[Explanation of symbols]

 101, 301 Antenna element 102 TR module 103 Local oscillator 104 Carrier oscillator 106 DSP 107 CPU 108, 109 Arithmetic circuit 201 Circulator 202, 304 Calibration signal switch 203 Amplifier 204, 211 Mixer 205, 213 Band filter 206 IQ detector 207 A / D converter 208 Decoder 209 Multiplexer 210 D / A converter 212, 303 Switch 214 Power amplifier 215 Coupler 302 Receiver module

Claims (9)

[Claims] 1. A multiplex wireless communication apparatus as a base station for performing wireless communication with a plurality of terminal stations, comprising: an array antenna including a plurality of antenna elements; and an array antenna corresponding to each of the antenna elements. A plurality of transmission / reception module means for demodulating a reception signal of the corresponding antenna element and converting a baseband transmission signal into a signal of a communication frequency band; and for each terminal station, based on each reception signal demodulated by the plurality of transmission / reception modules. First calculating means for analyzing the direction of arrival, delay time, and relative power; and second calculating means for calculating the direction of arrival of a direct wave for the terminal station based on the direction of arrival, delay time, and relative power of each of the received signals. Calculating means, and directivity calculating means for obtaining antenna directivity for suppressing unnecessary waves other than each of the direct waves and multiplexing these antenna directivities. Multiplex radio communication apparatus according to claim. 2. The multiplex radio according to claim 1, wherein said first calculating means calculates said arrival direction, delay time, and relative power by spectrum analysis of a signal received by said array antenna. Communication device. 3. The multiplex wireless communication apparatus according to claim 1, wherein the second arithmetic unit is configured to convert a signal having a minimum delay time into a direct wave. 4. The directivity calculating means according to claim 1, wherein said antenna directivity is obtained by a Howell-Applebaum algorithm.
The multiplex wireless communication device according to any one of the above. 5. The apparatus according to claim 1, wherein two sets of the array antennas are provided, one for analysis by the first arithmetic means, and the other for actual signal transmission and reception. The multiplex wireless communication device according to claim 1. 6. A measuring means for measuring a relative phase and a relative amplitude between circuits of said transmitting / receiving module means,
6. The apparatus according to claim 1, wherein said transmission / reception module means is provided in each of said transmission / reception module means, and corrects the relative phase and relative amplitude so as to perform the analysis processing of said first arithmetic means. A multiplex wireless communication device according to claim 1. 7. A multiplex wireless communication apparatus as a base station for performing wireless communication with a plurality of terminal stations, comprising: an array antenna including a plurality of antenna elements; and an array antenna corresponding to each of the antenna elements. A plurality of transmission / reception module means for demodulating a reception signal of the corresponding antenna element and converting a baseband transmission signal into a signal of a communication frequency band; an arrival direction of each baseband-converted reception signal from the plurality of transmission / reception modules; Delay time, analysis means for analyzing relative power, arrival direction of each of the received signals, delay time, means for obtaining a weight matrix for forming a multiplexed adaptive pattern based on relative power, this weight matrix A matrix operation with the baseband transmission signal is performed to provide the multiplexed baseband transmission signal to the transmission / reception module means. Means for, multiplex radio communication apparatus characterized by comprising means for obtaining a product sum of the demodulated signals from the transceiver module means and the weight matrix. 8. The apparatus according to claim 7, further comprising: means for calculating an amplitude deviation and a phase deviation of each of said transmission / reception module means; and correction means for correcting said weight vector in accordance with each of said deviations. Multiplexed wireless communication device. 9. The multiplex wireless communication apparatus according to claim 1, wherein the multiplex wireless communication apparatus is a base station used for the space division multiple access communication system.