RU2573270C2 - Adaptive correction method with compensation of guard time periods - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method envisages increase in duration of test signal by introduction of adaptive guard time periods (GTP) before and upon test signal, and due to this fact pulse response of the channel may be calculated without interference of unknown information symbols. At that GTP before and upon the first test signal are opposite to GTP before and upon the second test signal, and in result GTPs are compensated at summing.

EFFECT: improved accuracy of pulse response calculation for the correcting filter, which ensures high-speed data transmission and high interference resistance.

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Description

The invention relates to the field of electro-radio engineering, namely to radio communications technology, and can be used in single-frequency data transmission systems with adaptive correction of signals at the receiving side.

The essence of adaptive correction lies in constructing a correction filter (CF) that compensates for signal distortions resulting from multipath propagation in a communication channel, in particular, in a short-wavelength communication channel. The consequence of multipath propagation is intersymbol interference (MSI).

Closest to the claimed technical solution is the method of finding the impulse response (ИХ) of the channel, described in [Nikolaev B.I. Sequential transmission of discrete messages on continuous channels with memory. - M .: Radio and communications, 1988. - 264 s] and adopted for the prototype. The prototype method involves increasing the duration of the test signal by entering guard intervals (ZI) before and after the test signal, due to which their channel is calculated more accurately without interfering with the influence of unknown information symbols.

ZI are segments of harmonic oscillations or a cyclic continuation of the test signal. As a result, it is possible to get rid of only “overlapping” unknown information symbols on the test ones, while increasing the time for transmitting the test signal. However, the increase in the accuracy of calculating the IC of the communication channel and the corresponding IC of KF is insignificant, and as a result, the increase in noise immunity with respect to the method of finding the IC of the channel without ZI is insignificant [Nikolaev B.I. Sequential transmission of discrete messages on continuous channels with memory. - M .: Radio and communications, 1988. - 264 p.].

Thus, the disadvantage of the prototype is that with a slight gain in noise immunity, the information speed is significantly reduced, which is a high fee for the introduction of ZI.

The aim of the invention is to improve the accuracy of calculating the impulse response of the correction filter, providing high-speed transmission of information and high noise immunity.

This goal is achieved by the fact that the method of adaptive correction with compensation of protective intervals, which consists in increasing the duration of the test signal by entering protective intervals before and after the test signal, due to which the impulse response of the channel is calculated more accurately without interfering with the influence of unknown information symbols, while protective intervals before and after the first test signal are 180 ° opposite in phase to the protective intervals before and after the second test signal, these test signals The luminesces add up to the duration interval of two guard intervals and test signals, as a result of which the responses to the guard intervals before and after the test signal are compensated, and the signal-to-noise ratio on the test signal interval increases, the addition result is divided by two, after which the channel impulse response is calculated and corresponding impulse response of the correction filter.

The structural diagram of the proposed method is depicted in FIG. one,

where 1 is the delay line;

2 - adder;

3 - divisor by 2;

4 - block calculation of their channel and their CF.

Work on the method is as follows.

A signal is received at the input, the structure of which is shown in FIG. 2 and contains sequentially transmitted test and information signals separated from each other by a ZI (ZI-1 or ZI-2). In this case, the signal corresponding to ZI-1 is opposite to ZI-2. This means that the sum of these signals in the absence of noise and distortion is zero. From the output of the delay line (1) to the first input of the adder (2), a signal is received corresponding to the test signal and ZI before and after the test signal - S1. At the same time, the signal corresponding to the test signal and ZI before and after the test, S2, is supplied to the second input of the adder (2). In the adder (2), these signals are added, as a result of which a total test signal is obtained, which is divided by 2 in the divider by 2 (3). As a result of division, the power (amplitude) of the total test signal is close to the power (amplitude) of a single test signal. This is especially important when using quadrature amplitude manipulation (QAM), since after the correction procedure the amplitude of the information signal is restored to a conditional unit level. Then, the total test signal is fed to the input of the calculation unit for the channel and the KF KF (4), which calculate the channel and the corresponding KF using one of the known methods described, for example, in [Dzhigan V.I. Adaptive signal filtering: theory and algorithms. M .: Technosphere, 2013. - 528 p.]. At the output, they receive the CTF necessary for further tuning of the CF and correction of the information signal.

Improving the accuracy of calculating the IC of the communication channel and the corresponding IC of KF is achieved due to two factors: firstly, when the signals S1 and S2 are added, the response to the ZI before and after the test signal is compensated, secondly, the power of the test signal is doubled, and the power of additive noise is not therefore, the signal-to-noise ratio in the interval of the test signal increases. Both of these factors contribute to a more accurate calculation of the IC of the communication channel and the corresponding IC of the CF, which as a result increases the noise immunity.

The present invention can be used for single-frequency data transmission systems with adaptive signal correction at the receiving side. A distinctive feature of the described device is the introduction of ZI between test and information signals, and the signals corresponding to ZI between the nearest test signals are opposite to each other. As a result of addition, the protective intervals are compensated, due to which it is possible to more accurately calculate their CF, which as a result increases the noise immunity. This, in turn, allows transmitting information signals of increased modulation frequency, thereby providing high-speed transmission of information and higher noise immunity.

Claims (1)

Adaptive correction method with compensation of protective intervals, which consists in increasing the duration of the test signal by entering protective intervals before and after the test signal, due to which the channel impulse response is calculated more accurately without interfering with the influence of unknown information symbols, characterized in that the protective intervals before and after the first test signal, 180 ° opposite in phase to the guard intervals before and after the second test signal, these test signals add up to the interval the duration of the two guard intervals and test signals, as a result of which the responses to the guard intervals before and after the test signal are compensated, and the signal-to-noise ratio on the test signal interval increases, the addition result is divided into two, after which the impulse response of the channel and the corresponding impulse response of the correction filter.

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