JP2001223623A - Digital radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in the conventional digital radio communication system, which effectively utilizes a method by which an array antenna separates and suppresses a multiplex wave and an interference wave depending on the difference from the arrival directions, that has required a large scale of an arithmetic unit to calculate a complex weight vector of the array antenna, requiring a high calculation quantity and an increased power consumption required for the arithmetic operation, in the case of adopting the array antenna for a mobile station whose lower power consumption is a requirement. SOLUTION: The digital radio communication system is configured, such that the array antenna of the mobile station receives a reference signal sent from a base station and a waveform memory stores a complex base band signal of a wireless signal received by each antenna element. The mobile station transmits each of the stored complex base band signals to the base station as transmission data, and the base station side calculates the complex weight vectors of the mobile station array antenna and transmits the calculated complex weight vector to the mobile station as transmission data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for an array antenna.

[0002]

2. Description of the Related Art In digital mobile communication, a reflected wave, a diffracted wave and the like in addition to a direct wave are superimposed to form a multipath propagation path in which a plurality of waves having different arrival times are combined, thereby causing frequency selective fading. An interference wave from another station arrives. As a method of improving frequency selective fading and interference by other stations, there is a spread spectrum communication system. RAKE reception which separates and combines multiplexed waves having different arrival times on a time axis by sufficiently widening a spread bandwidth of a spread modulation signal. A method is used. However, when the spread bandwidth cannot be sufficiently widened and the multiplexed wave cannot be separated on the time axis, a method of separating and suppressing the multiplexed wave or the interference wave by the array antenna depending on the arrival direction of the multiplexed wave is effective. The array antenna utilizes the fact that the directivity of the antenna changes when an amplitude and a phase shift (weighted by a complex weight vector) are performed on each signal received by each antenna element and combined. A complex weight vector of each antenna is determined based on a known control algorithm, and unnecessary direct waves and interference waves are separated and suppressed by controlling directivity while adapting to environmental changes.
As a control algorithm for determining a complex weight vector of each antenna of the array antenna, an MMSE (MiSE) which has a waveform of a desired signal as prior information and uses a root-mean-square of an error of an array-combined output with respect to the desired signal as an evaluation function.
Algorithms based on the (Nimum Mean Square Error) criterion are well known. The LMS (Least Mean Squares) method or RLS (Recursive) method for finding an approximate solution by successive update for the optimal solution (Winner solution) based on the MMSE standard
Least Squares) method, and SMI that directly calculates approximate solutions
(Sample Matrix Inverse) method.

FIG. 5 is a block diagram of a digital radio communication system using the conventional SMI method. Antenna element 50
Array antennas 501 to 504, RF receivers 505 to 507 for amplifying a radio signal having a radio frequency received by each antenna element and converting the frequency to an intermediate frequency signal having a predetermined intermediate frequency, and each intermediate frequency signal / D converters 508 to 510 for converting into a digital signal
Quasi-synchronous detectors 511 to 513 for converting an intermediate frequency after A / D conversion into a complex baseband signal, and a DBF (Digital Beam) for calculating a complex weight vector and weighting and adding each complex baseband signal with a complex weight vector. Formin
g) a unit 514 and a demodulator 515 that performs synchronous detection or delay detection from the weighted and added complex baseband signal and outputs desired reception data.

FIG. 6 is a block diagram of the DBF unit, which shows the correlation matrix of each complex baseband signal and its inverse matrix,
A weight vector calculation unit 605 for calculating a product of a correlation vector of each complex baseband signal and a reference signal, and a product of an inverse matrix and a correlation vector, and a multiplier 601 to 603 for multiplying each complex baseband by the obtained weight vector, An in-phase adder 604 for in-phase addition is provided.

[0005] First, a signal arriving through a multiplex wave propagation environment is received by antenna elements 502 to 504 which are juxtaposed and arranged at an interval of about a half wavelength of a carrier frequency for wireless communication. The radio signal of the reference signal transmitted from the base station received by the antenna elements 502 to 504 is transmitted to the RF receiver 505
The signal is amplified at 507, frequency-converted to an intermediate frequency having a predetermined intermediate frequency, and input to quasi-synchronous detectors 511 to 513 via A / D converters 508 to 510.

The quasi-synchronous detectors 511 to 513 perform quasi-synchronous detection on the intermediate frequency signal after the A / D conversion, convert the intermediate frequency signal into a complex baseband signal, and input the complex baseband signal to the DBF section 514. DBF part 5
At 14, each complex baseband signal is input to the weight vector calculator 605, and a correlation matrix of each complex baseband signal and a correlation vector between each complex baseband signal and a reference signal are calculated.

After calculating the inverse matrix of the correlation matrix, the product of the obtained inverse matrix and the correlation vector is calculated to determine the complex weight vector of the array antenna. Next, the determined complex weight vector is multiplied by each complex baseband signal received by each antenna element by multipliers 601 to 603, added in phase by an in-phase adder 604, and input to a demodulator 515. The demodulator 515 performs synchronous detection or delay detection from the weighted and added complex baseband signal and outputs desired reception data.

As described above, in order to determine a complex weight vector for separating and suppressing a multiplex wave and an interference wave from another station using an array antenna, the SMI method requires a large correlation matrix, its inverse matrix, and the correlation matrix. Vectors need to be calculated. Although the RLS method and the LMS method can reduce the amount of calculation as compared with the SMI method, it takes time to converge the solution because an approximate solution is obtained by successive updating.

[0009]

As described above, it is effective to use the array antenna to separate and suppress the multiplexed waves and the interference waves depending on the arrival direction of the interference waves. When a conventional array antenna is used, the configuration of the above-described conventional technology is often provided in a base station. In this case, the complex weight vector of the base station array antenna is calculated and used in the base station itself. When an array antenna is used for a mobile station, the configuration of the above-described conventional technique is provided in the mobile station, and the complex weight vector of the mobile station array antenna is calculated and used in the mobile station itself. However, the calculation of the complex weight vector of the array antenna having a large amount of calculation requires a large-scale arithmetic device and an increase in power consumption at the time of calculation. Therefore, a reduction in the size and power consumption of the device is required. This is problematic when used in mobile stations.

[0010]

According to the digital radio communication system of the present invention, a reference signal transmitted from a base station is received by an array antenna of a mobile station, and a complex baseband signal of the radio signal received by each antenna element is converted into a waveform. Store in memory. Each of the stored complex baseband signals is transmitted to the base station as transmission data, the base station calculates a complex weight vector of the mobile station array antenna, and transmits the calculated complex weight vector to the mobile station as transmission data. The mobile station receives this and uses it as a complex weight vector of the mobile station array antenna to separate and suppress the multiplex wave and the interference wave from other stations.

As described above, the digital radio communication system of the present invention calculates the complex weight vector of the array antenna of the mobile station on the base station side, so that the mobile station does not need to have an arithmetic unit, and the apparatus can be reduced in size and reduced in size. Power consumption can be realized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram showing an embodiment of a mobile station to which a digital radio communication system according to the present invention is applied. The digital radio communication system according to the present embodiment controls the directivity of an array antenna composed of a plurality of antenna elements that are juxtaposed and arranged close to each other at an interval of about a half wavelength of a carrier frequency for performing radio communication, thereby forming a multi-wave propagation path. It separates and suppresses multiplexed waves and interference waves from other stations depending on the direction of arrival of the incoming waves. It is characterized in that the weight vector is obtained on the base station side.

An array antenna 101 having antenna elements 102 to 104, and an RF receiver 105 for amplifying a radio signal having a radio frequency received by each antenna element and converting the frequency into an intermediate frequency signal having a predetermined intermediate frequency.
107, A / D converters 108 to 110 for converting each intermediate frequency signal into a digital signal, and a quasi-synchronous detector 1 for converting the intermediate frequency after the A / D conversion into a complex baseband signal
11 to 113; a weighting and adding unit 114 for weighting and adding each complex baseband signal with a complex weight vector; and a demodulator 11 for performing synchronous detection or delay detection from the weighted and added complex baseband signal and outputting desired reception data.
5 and a weight vector memory 116 for storing the complex weight vector obtained by the base station.

[0015] Further, a waveform memory 117 for storing each complex baseband signal subjected to quasi-synchronous detection, and a quadrature modulator for modulating each of the stored complex baseband signal and transmission baseband signal to an intermediate frequency signal having a predetermined intermediate frequency. 118 and D for converting the intermediate frequency signal to an analog signal.
A / A converter 119, an RF transmitter 120 for frequency-converting the intermediate frequency signal after the D / A conversion into a radio signal having a radio frequency and amplifying the radio signal to a predetermined power, and a transmission antenna 121 for transmitting the radio signal.

FIG. 2 is a block diagram of the weighting and adding unit, which includes multipliers 201 to 203 for multiplying each complex baseband by a weight vector, and an in-phase adder 204 for in-phase adding the multiplied signals.

Each of the antenna elements 102 to 104 to the quasi-synchronous detectors 111 to 113 in the array antenna 101 are connected in a dependent manner for each antenna element system, and the signal processing for each system is executed in the same manner. , Antenna element 1
The processing for the radio signal received at 02 will be described.

The radio signal of the reference signal transmitted from the base station received by the antenna element 102 is amplified by the RF receiver 105 and frequency-converted into an intermediate frequency having a predetermined intermediate frequency.
The signal is input to the quasi-synchronous detector 111 via the A / D converter 108. The quasi-synchronous detector 111 performs quasi-synchronous detection on the intermediate frequency signal after the A / D conversion and converts the signal into a complex baseband signal. Similarly, the complex baseband signal obtained for each system is input to the waveform memory 117 and stored.

Each of the stored complex baseband signals is input to quadrature modulator 118, modulated to an intermediate frequency signal having a predetermined frequency, and input to D / A converter 119. The intermediate frequency signal after the D / A conversion is input to the RF transmitter 120, frequency-converted to a radio signal having a radio frequency, amplified to a predetermined power, and transmitted to the base station via the transmission antenna 121.

FIG. 3 shows a block diagram of the base station. An antenna 301, a circulator 302 for sharing the antenna 301 for transmission and reception, and an antenna 30 for the base station.
An RF receiver 303 for amplifying a radio signal having a radio frequency received in 1 and converting the frequency into an intermediate frequency signal having a predetermined intermediate frequency; an A / D converter 304 for converting each intermediate frequency signal into a digital signal; A quasi-synchronous detector 305 for converting the intermediate frequency after the A / D conversion into a complex baseband signal, and a demodulator 306 for performing synchronous detection or delay detection from the complex baseband signal and outputting desired reception data.
A waveform memory 307 for storing a complex baseband signal transmitted from the mobile station, and a weight vector calculator 3 for calculating a complex weight vector from the complex baseband signal of the mobile station.
08, a weight vector memory 309 for storing the obtained weight vector, a quadrature modulator 310 for modulating the stored complex weight vector and the transmission baseband signal to an intermediate frequency signal having a predetermined intermediate frequency, A D / A converter 311 for converting the signal into a signal and an RF transmitter 312 for frequency-converting the intermediate frequency signal after the D / A conversion into a radio signal having a radio frequency and amplifying the signal to a predetermined power are provided.

A radio signal of each of the complex baseband signals transmitted from the mobile station is received by an antenna 301, and the received radio signal is transmitted via a circulator 302 to an RF receiver 3.
The signal is amplified by an RF receiver 303, frequency-converted to an intermediate frequency having a predetermined intermediate frequency, and input to a quasi-synchronous detector 305 via an A / D converter 304. The quasi-synchronous detector 305 performs quasi-synchronous detection on the intermediate frequency signal after the A / D conversion and converts the signal into a complex baseband signal. This means that the base station has obtained a complex baseband signal in which the reference signal has been received by each antenna element of the array antenna of the mobile station.

Each complex baseband signal is input to weight vector calculation section 308, and the complex weight is calculated at the base station using the above-described SMI method. First, a weighting matrix calculation unit 308 calculates a correlation matrix from each complex baseband signal, and further obtains the inverse matrix.

Next, a complex vector is calculated by calculating a correlation vector between each complex baseband signal and the reference signal, and calculating a product of the inverse matrix of the correlation matrix. Next, the obtained complex weight vector is stored in the weight vector memory 309.

Further, the accumulated complex weight vector is input to quadrature modulator 310, modulated to an intermediate frequency signal having a predetermined frequency, and input to D / A converter 311. The intermediate frequency signal after the D / A conversion is input to the RF transmitter 312, frequency-converted into a radio signal having a radio frequency, amplified to a predetermined power, and transmitted to the mobile station via the circulator 302 and the antenna 301.

The mobile station receives the radio signal received by the antenna element 102 and performs the same signal processing as in the system from the antenna element 102 to the quasi-synchronous detector 111 to obtain a complex baseband signal. The obtained complex baseband signal is input to a demodulator 115, and synchronous detection or delay detection is performed, and a complex weight vector obtained by the base station is input to a weight vector memory 116 as received data and stored.

Thereafter, until the next update of the complex weight vector, the radio signal is received using the accumulated complex weight vector when data is transmitted from the base station to the mobile station. The complex weight vector stored in the weight vector memory 116 in the weighting addition unit and each complex baseband signal obtained by performing signal processing similar to that of the system from the antenna element 102 to the quasi-synchronous detector 111 for each system. Multipliers 201-
The signal is multiplied by 203, added in phase by an in-phase adder 204, and input to the demodulator 115.

The demodulator 115 performs synchronous detection or delay detection from the complex baseband signal weighted and added, and outputs desired reception data. This makes it possible to obtain a received wave in which unnecessary multiple waves and interference waves are separated and suppressed.

In this embodiment, the antennas 102 to 1
04 to the multipliers 201 to 203 of the weighting addition unit 114
The case where the system up to 3 is 3 is shown, but it is not particularly limited as long as it is 2 or more.

The updating of the complex weight vector is performed at least twice as long as the maximum Doppler frequency obtained by dividing the maximum moving speed of the mobile station by the wavelength of the carrier frequency, thereby enabling the movement of the mobile station and the environment of the propagation path. The reception can be performed following the change in the arrival direction due to the change.

(Embodiment 2) FIG. 4 is a block diagram showing another embodiment of a mobile station to which the digital radio communication system of the present invention is applied. Except for the circulators 405 to 407 for using the array antenna for transmission and reception, the receiving section of the present embodiment has the same purpose as that of the first embodiment, and includes an array antenna 401 having antenna elements 402 to 404,
Receivers 408 to 410 and A / D converters 411 to 413
Quasi-synchronous detectors 414 to 416 and the weighting and adding unit 4
19, demodulator 417, weight vector memory 418
And a waveform memory 420.

The configuration of the weighted addition unit is the same as that of the first embodiment shown in FIG. 2, and includes multipliers 201 to 203 and an in-phase adder 204.

Further, an in-phase distributor 421 for in-phase distribution of the transmission baseband signal, and multipliers 422 to 422 for multiplying each of the in-phase distributed transmission baseband signals by a complex weight vector.
424, quadrature modulators 425 to 427 for modulating each multiplied transmission baseband signal to an intermediate frequency signal having a predetermined intermediate frequency, and D / A converters 428 to 430 for converting each intermediate frequency signal to an analog signal. And RF transmitters 431 to 4 for frequency-converting each intermediate frequency signal after D / A conversion into a radio signal having a radio frequency and amplifying it to a predetermined power.
33. The base station is the same as in Embodiment 1 shown in FIG.

The signal processing from the reception of the radio signal of the reference signal transmitted from the base station to the accumulation of the complex burst band signal in the waveform memory 420 is performed by transmitting the radio signal from the antenna element 402 via the circulator 405 to the RF receiver 408.
Are the same as those in the first embodiment, except that the input is made, so that the description is omitted.

Next, each of the accumulated complex baseband signals is converted into an intermediate frequency signal having a predetermined frequency by a quadrature modulator 425 and input to a D / A converter 428. The intermediate frequency signal after the D / A conversion is input to the RF transmitter 431, frequency-converted into a radio signal having a radio frequency, amplified to a predetermined power, and transmitted to the base station via the circulator 405 and the antenna element 402.

The base station performs the same processing as in the first embodiment to obtain a complex weight vector and transmits it to the mobile station. The mobile station performs the same signal processing as in the first embodiment on the antenna element 402.
From the demodulator 417 to store the complex weight vector in the weight vector memory 419. Thereafter, the radio signal is transmitted and received using the accumulated complex weight vector at the time of data transmission and reception between the base station and the mobile station until the next update of the complex weight vector.

At the time of mobile station reception, weighting and adding section 419
, The complex weight vector stored in the weight vector memory 418 and the quasi-synchronous
14 and the complex baseband signals obtained by performing the same signal processing for each system as the multipliers 201 to 203.
, And added by the in-phase adder 204 and input to the demodulator 417. The demodulator 417 performs synchronous detection or delay detection from the complex baseband signal weighted and added, and outputs desired reception data. As a result, the mobile station can obtain a received wave in which unnecessary multiple waves and interference waves are separated and suppressed.

At the time of mobile station transmission, the transmission baseband signal is in-phase distributed by the in-phase distributor 421. Hereinafter, the multiplier 42
2 to 424 to the antenna elements 402 to 404 are cascade-connected for each system of each antenna element, and the signal processing for each system is similarly executed. The in-phase distributed transmission baseband signal and the complex weight vector stored in the weight vector memory 418 are multiplied by multipliers 422 to 424, respectively, input to quadrature modulators 425 to 427, and modulated to intermediate frequency signals having a predetermined frequency. D / A converter 42
8 to 430.

Each of the intermediate frequency signals after the D / A conversion is input to the RF transmitters 431 to 433, frequency-converted into a radio signal having a radio frequency, amplified to a predetermined power, and each radio signal is transmitted to the circulators 405 to 407. Antenna elements 402 to
404 to the base station. As a result, the base station can obtain a received wave in which unnecessary multiplex waves are separated and suppressed.

In this embodiment, the antenna element 40
From 2 to 404, the multipliers 201 to 201 of the weighting addition unit 419
Although the case where the number of systems up to 203 and the number of systems from multipliers 422 to 424 to antenna elements 402 to 404 are 3 is shown, the number is not particularly limited as long as it is 2 or more.

The updating of the complex weight vector is performed according to the first embodiment.
In the same way as described above, by changing the maximum moving speed of the mobile station by the wavelength of the carrier frequency at least twice as long as the maximum Doppler frequency, the change in the direction of arrival due to the movement of the mobile station and environmental changes in the propagation path Can be transmitted and received.

[0041]

As is apparent from the above embodiment, the present invention transmits a complex baseband signal of a reference signal transmitted from a base station received by each antenna element of a mobile station to the base station, and the mobile station transmits the complex baseband signal. By calculating the complex weight vector of the station array antenna and using the calculated complex weight vector as the complex weight vector of the mobile station array antenna to separate and suppress multiple waves and interference waves from other stations, It is not necessary to have a weight vector computing device, so that the device can be reduced in size and power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a mobile station to which a digital wireless communication system according to the present invention is applied.

FIG. 2 is a block diagram of a weighting and adding unit of the mobile station.

FIG. 3 is a block diagram of an embodiment of a base station to which the digital wireless communication system according to the present invention is applied;

FIG. 4 is a block diagram of another embodiment of a mobile station to which the digital wireless communication system according to the present invention is applied;

FIG. 5 is a block diagram of a digital wireless communication system using a conventional SMI method.

FIG. 6 is a block diagram of a DBF unit;

[Explanation of symbols]

 101 Array antenna 102-104 Antenna element 105-107 RF receiver 108-110 A / D converter 111-113 Quasi-synchronous detector 114 Weight adder 115 Demodulator 116 Weight vector memory 117 Waveform memory 118 Quadrature demodulator 119 D / A converter 120 RF transmitter 121 Transmission antenna 201-203 Multiplier 204 In-phase adder 301 Antenna 302 Circulator 303 RF receiver 304 A / D converter 305 Quasi-synchronous detector 306 Demodulator 307 Waveform memory 308 Weight vector calculator 309 Weight vector memory 310 Quadrature demodulator 311 D / A converter 312 RF transmitter 401 Array antenna 402-404 Antenna element 405-407 Circulator 408-410 RF receiver 411-413A D converters 414 to 416 Quasi-synchronous detector 417 Demodulator 418 Weight vector memory 419 Weighting adder 420 Waveform memory 421 In-phase distributor 422 to 424 Multiplier 425 to 427 Quadrature demodulator 428 to 430 D / A converter 431 to 433 RF transmitter 501 Array antenna 502-504 Antenna element 505-507 RF receiver 508-510 A / D converter 511-513 Quasi-synchronous detector 514 DBF section 515 Demodulator 601-603 Multiplier 604 In-phase adder 605 Weight vector Arithmetic unit

Continued on the front page (72) Inventor Yuji Igata 1006 Kazuma Kadoma, Kazuma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 5J021 AA05 AA06 CA06 DB02 DB03 FA14 FA15 FA16 FA17 FA20 FA24 FA26 FA28 FA29 FA30 FA32 GA02 HA05 HA10 5K059 CC02 CC03 CC04 DD35 DD39 EE02 5K067 AA02 AA42 CC24 GG11 KK03

Claims (2)

[Claims] In a digital radio communication system in which a mobile station has an array antenna composed of a plurality of antenna elements, a predetermined reference signal is wirelessly transmitted from a base station, and the mobile station transmits a predetermined reference signal to each antenna element of the array antenna. A received signal of the received reference signal is converted into a digital waveform signal that is discretized on both the time axis and the amplitude axis, and the converted digital waveform signal is wirelessly transmitted to a base station. A base station for calculating a correlation matrix of a plurality of digital waveform signals, and a correlation vector between the reference signal and the plurality of digital waveform signals, and using the correlation matrix and the correlation vector, each antenna element of an array antenna of a mobile station; And the root mean square error between the signal and the reference signal when the received signal is weighted and combined with the weight vector is minimized. The weight vector of the mobile station array antenna is calculated in the base station, and the weight vector of the mobile station array antenna calculated in the base station is wirelessly transmitted from the base station to the mobile station as transmission data. Digital wireless communication system. 2. The digital radio communication system according to claim 1, wherein the updating of the weight vector of the mobile station array antenna is performed at least twice the maximum Doppler frequency.