JPH07183837A - Equalizing demodulator - Google Patents

Abstract

PURPOSE:To provide an equalizing demodulator which is used for the receiver of a radio communication system for which a TDMA and a digital modulation system are used and is capable of improving the error rate improving characteristic of an equalizer by combining signals which are strong in sequence correlation when signals obtained from each reception system composing a diversity system are synthesized. CONSTITUTION:The error rate improving characteristic of an equalizer can be improved by sampling an orthogonal base band signal subjected to asynchronous orthogonal detection for a received modulation wave at an interval of the reciprocal-of-an-integer (equal to 2 or more) multiple of the tap interval of the feed forward filter part of a DFE 110 and by performing an equalization processing by using the correlation signal of a frame synchronization part 111 performing a frame synchronization by using the sequence correlation from the sampled orthogonal base band signal as the input signal of the equalizer by combining signal series which are strong in a series correlation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a time division multiplexing system (hereinafter,
It is used for a receiver of a digital wireless communication system using TDMA (abbreviated as TDMA), and has spatial diversity using a plurality of antennas and a decision feedback equalizer (hereinafter, DF).
The present invention relates to an equalization demodulator capable of improving the error rate improvement characteristic of the equalizer in a combination diversity equalizer having a combination of (E).

[0002]

2. Description of the Related Art In recent years, T which performs digital data communication
Research and development of digital mobile radio communication systems using DMA have been active. In mobile radio communication, it is necessary to take measures against the deterioration of the transmission line, which cannot be avoided by communication between mobiles, such as multipath and fading.
As one of the countermeasures, there is a method of using a space diversity using a plurality of antennas effective for fading and a synthetic diversity equalizer combining DFE effective for multipath (for example, JP-A-3-34262).
7 publication).

A conventional combining diversity equalizer will be described below. FIG. 4 shows a block configuration of a conventional combining diversity equalizer. In FIG. 4, 40
1, 402 are receiving antennas. Reference numerals 403 and 404 denote receivers for amplifying and frequency-converting received signals, and 405 and 406.
Is a band limiting filter (hereinafter abbreviated as BPF). A switch 407 switches the outputs of the BPFs 405 and 406 at each half time interval of the symbol rate of the digital modulation wave. A quadrature demodulator 408 converts the input signals from the reception antennas 401 and 402 into a quadrature baseband signal. Reference numeral 409 is a sampling unit that samples an orthogonal baseband signal and digitally converts it, and 410 is a DFE.

The operation of the synthetic diversity equalizer configured as described above will be described below.

First, the two-system modulated signals in the carrier wave (hereinafter abbreviated as RF) band received by the two-system antennas 401 and 402 are intermediate frequencies (hereinafter abbreviated as IF) by the receiving units 402 and 403. The frequency is converted into a band, and the band is limited by the BPFs 405 and 406. Next, the IF signals of the two systems are switched by the switch 407 at every half time interval of the symbol rate, and 408
Is converted into a quadrature baseband signal by the quadrature demodulator. The converted quadrature baseband signal is sampled by the sampling unit 409, converted into digital data, equalized by the DFE 410, and output as equalized demodulated data.

[0006]

However, in the above-mentioned conventional configuration, since signals are switched and sampled at time intervals of half the symbol rate, one system of signals is the maximum opening point of the eye pattern of the demodulated signal. When the signal is sampled by, the signal of the other system is sampled at the transition point of the signal whose timing is shifted by a half symbol length, which causes a problem that the maximum diversity effect cannot be obtained. Was there.

The present invention solves the above-mentioned conventional problems. In a receiver of a digital radio communication system using TDMA, when the signals obtained from the respective reception systems constituting the diversity system are combined, the sequence correlation is obtained. It is an object of the present invention to provide an equalization demodulator capable of improving the error rate improvement characteristic of the equalizer by combining the signals having a strong signal.

[0008]

In order to achieve this object, an equalization demodulator of the present invention uses a quadrature baseband signal obtained by asynchronous quadrature detection of a received modulated wave to obtain a tap interval of 2 in a feedforward filter section of a DFE. An equalizer that combines signal sequences with strong sequence correlation by using a correlation signal of a frame sync unit that performs frame synchronization from the sampled orthogonal baseband signal by sampling at intervals of the above integer The input signal of 1 is subjected to equalization processing.

[0009]

With this configuration, in the equalization demodulator using the combining diversity by the switching method, the information of the digital modulation signal input from each antenna can be effectively used, so that the error rate improving characteristic of the equalizer is improved. Can be improved.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 101 and 102 are receiving antennas, 103 and 104 are receiving sections, and 105 and 106 are IFs.
A band band limiting filter, 107 is an IF band changeover switch, 108 is an asynchronous quadrature demodulator, 109 is a data sampling unit, 110 is DFE, and 111 is a frame sync unit.

The operation of the equalization demodulator configured as described above will be described below with reference to FIG.

First, the two-system modulated signals received by the two-system antennas 101 and 102 are received by the receiving unit 102,
After frequency conversion to the IF band by 103, band limitation is performed by band limiting filters 105 and 106. The band-limited two-system IF band received signals are transmitted to the switch 10
At 7, the signal is switched every half time interval of the symbol rate, and is converted to a quadrature baseband signal by the asynchronous quadrature demodulator 108. The converted orthogonal baseband signal is 1
In the data sampling unit 09, sampling is performed by an integer multiple of 2 per symbol and converted into digital data, which is then sent to the frame sync unit 111. The frame sync unit 111 generates a frame synchronization signal from the transmitted orthogonal digital data by using serial correlation. The correlation signal obtained at this time is sent to the data sampling section 109. In the data sampling unit 109, from the sampled orthogonal baseband signals,
Based on the correlation signal sent from the frame sync unit 111, a signal sampled at the timing having the strongest series correlation is selected from the two-system reception signals and is used as the DFE input signal 110. DFE110
In, the input signal is equalized, and equalized demodulated data is obtained.

Next, the data sampling timing will be described with reference to FIG. In FIG.
201 in (a) is the data before sampling, FIG. 2 (b)
202 is the operation clock of the changeover switch, FIG.
Reference numeral 203 in (c) is a sampling clock.

The two systems of quadrature demodulated data are switched by the switching clock 202, and the data 201
Becomes The data 201 is the sampling clock 203
Thus, sampling is performed a plurality of times at each switching timing. From the sampled data, the one with a timing with a strong series correlation is selected and used as the input to the equalizer.

As described above, according to this embodiment, the sampling unit 1
09 and the frame sync unit 111 are combined, and the received data at the sampling timing with strong sequence correlation is input to the equalizer, so that the error rate improvement characteristic of the equalizer can be improved.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, reference numeral 301 in FIG. 3A is data before sampling, reference numeral 302 in FIG. 3B is an operation clock of the changeover switch, and reference numeral 303 in FIG. 3C is a sampling clock.

The quadrature demodulated data of the two systems is switched by the switching clock 302 for each symbol that is an integer multiple of 2 or more and becomes data 301.
The data 301 is sampled once at each switching timing by the sampling clock 303. From the sampled data,
The one with a timing with a strong series correlation is selected as the input to the equalizer.

The block configuration of the equalization demodulator in this embodiment is the same as that in the first embodiment.

As described above, according to this embodiment, the sampling section and the frame sync section are combined with each other, and the received data at the sampling timing having a strong series correlation is input to the equalizer, thereby improving the error rate improving characteristic of the equalizer. Can be made. In the first and second embodiments, the total number of antennas is 2
Although the number is a book, any number may be used as long as it is an integer of 2 or more.

[0022]

As described above, according to the present invention, an IF switch unit for switching a plurality of IF band signals at a symbol interval of a fraction of the number of receiving antennas, and a quadrature baseband by the asynchronous quadrature detection of the switched IF band signals. A quadrature demodulation unit for converting into a signal and a quadrature baseband signal subjected to asynchronous quadrature detection 1
By providing a sampling unit that performs sampling with an integer multiple of 2 or more of the number of receiving antennas per symbol, and a frame sync unit that performs frame synchronization from the sampled orthogonal baseband signal using sequence correlation, sampling timing with strong sequence correlation The signal sequence of can be used as the input of the equalizer, and an equalization demodulator having excellent error rate improvement characteristics can be realized. .

[Brief description of drawings]

FIG. 1 is a block connection diagram of an equalization demodulator according to a first embodiment of the present invention.

FIG. 2 is a clock timing diagram of the equalization demodulator according to the first embodiment.

FIG. 3 is a clock timing chart of the equalization demodulator according to the second embodiment of the present invention.

FIG. 4 is a block connection diagram of a conventional frame signal processing device.

[Explanation of symbols]

 101, 102, 401, 402 receiving antenna 103, 104, 403, 404 receiving unit 105, 106, 405, 406 BPF 107, 407 changeover switch 108, 408 quadrature demodulating unit 109, 409 data sampling unit 110, 410 DFE 111 frame sync Part 201, 301 Data before sampling 202, 302 Switching clock 203, 303 Sampling clock

Claims (2)

[Claims] 1. A plurality of receiving antennas, a receiving unit for converting a received carrier-band modulated signal into an intermediate frequency band, a band-limiting filter having a minimum bandwidth required for reception in the intermediate frequency band, and a plurality of receiving units. An intermediate frequency band switch unit that switches the signal in the intermediate frequency band at intervals of a symbol of the receiving antenna, and an orthogonal demodulation unit that converts the switched intermediate frequency band signal into an orthogonal baseband signal by asynchronous orthogonal detection, A sampling unit that samples the orthogonal baseband signal that has been subjected to asynchronous orthogonal detection at an integer multiple of 2 or more of the number of receiving antennas per symbol; a frame sync unit that performs frame synchronization from the sampled orthogonal baseband signal using serial correlation; A transbar in which the tap interval of the feedforward filter is one symbol of the total number of receiving antennas An equalization demodulator including a monkey decision feedback equalizer. 2. A plurality of receiving antennas, a receiving unit for converting a received received modulated signal of a carrier band into an intermediate frequency band, and a band limiting filter having a minimum bandwidth required for reception in the intermediate frequency band. , 1 for multiple intermediate frequency bands
An intermediate frequency band switch unit that switches at an integer multiple of 2 or more of the number of receiving antennas per symbol, a quadrature demodulation unit that converts a signal in the switched intermediate frequency band into a quadrature baseband signal by asynchronous quadrature detection, and a quadrature that performs asynchronous quadrature detection The sampling unit that samples the baseband signal at the switching timing of the intermediate frequency band switch unit, the frame sync unit that performs frame synchronization from the sampled orthogonal baseband signal using serial correlation, and the tap interval of the feedforward filter are received. An equalization demodulator including a decision feedback equalizer, which is one symbol of the total number of antennas.