JPH0537407A - Selectivity phasing distortion compensating method - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency of transmitting data and to reduce the calculation processed variable of compensation whe compensating the selectivity phasing distortion of a radio line in digital mobile radio communication. CONSTITUTION:The transmission side transmits a transmitting signal inserting an impulse signal 13 having no transmission blocks 12 before and behind the signal in transmitting data 11 to the radio line in a fixed cycle, and the reception side estimates the selectivity phasing distortion of the radio line receiving the detected impulse signal 13 and compensates the distortion of the transmitting data 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for compensating for selective fading distortion in digital mobile radio communication.

[0002]

2. Description of the Related Art Selective fading is one of the main line failures in digital mobile radio communications. This selective fading is also called multipath delay distortion, and when the received wave arrives via multiple communication channels, if the delay spread is too large to be ignored compared to the symbol length of the transmission code, This is an obstacle that causes interference and that the frequency characteristic of the delay time in the transmission band is not flat but selective. As a method for eliminating the influence of the above-mentioned selective fading, conventionally, on the transmission side, as shown in FIG. 4, in the transmission signal (information symbol 41), training by a known PN code sequence on both the transmission side and the reception side is performed. The signal 42 is periodically inserted and transmitted, and on the other hand, the receiving side estimates and extracts the impulse response of the transmission path by the correlation calculation between the training signal 42 which the receiving side itself has and the received signal received, and the estimation is performed. A method of estimating and compensating for the distortion due to the selective fading by using the impulse response is used.

[0003]

However, in the above-mentioned conventional method, since the training signal used for correctly estimating the impulse response of the circuit needs to have a sharp autocorrelation characteristic, a long section is generally required, and the training signal is transmitted. There is a problem that the transmission efficiency of information is reduced because the overhead increases. Further, since the correlation calculation involves a product-sum calculation process of the number of steps which is proportional to the length of the training signal for each symbol reception, there is a problem that the load of hardware and software is large. The present invention solves the problems of transmission efficiency and the amount of calculation processing that occur in the above-mentioned conventional methods, so that the transmission efficiency is relatively high and the selective fading distortion compensation that can easily obtain the impulse response of the transmission path is performed. The purpose is to provide a method.

[0004]

A selective fading distortion compensation method of the present invention is a transmission signal in which an impulse signal having a non-transmission section of a predetermined length before and after is inserted in a transmission data from a transmission side at a constant cycle. , The receiving side detects the impulse signal from the transmission signal received via a wireless line, and detects each of the preceding wave component and the delayed wave component of the impulse signal generated by the selective fading of the wireless line. The amplitude information and the phase information are determined, the selective fading distortion at the timings of all the symbols in the transmission data is estimated by the interpolation processing based on the amplitude information and the phase information, and the delay equalization method or the maximum value is estimated by the estimated value. It is characterized in that the selective fading distortion is corrected by using likelihood determination.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of the configuration of a data transmission format of the present invention, which is an example of a data transmission format sent from a transmitting side for compensating for selective fading distortion. In the figure, 11 is an information symbol to be transmitted.
Reference numeral 12 is a non-transmission section that is repeatedly provided at a constant cycle between the information symbols 11 to be transmitted. In the non-transmission section 12, impulses 13 are formed at intervals of m symbols and n symbols (m and n are natural numbers). It is arranged.

In the non-transmission interval lengths of m symbols and n symbols provided before and after the impulse 13, the information symbol 11 arranged before the impulse 13 affects the impulse 13 by selective fading. The length is set so that it does not extend and the influence of the selective fading of the impulse 13 itself does not appear in the subsequent information symbol 11. The non-transmission period and the impulse insertion period length inserted by the above configuration are (m
Since + n + 1) symbols, for example, when considering a delay amount of at most 1 symbol as a transmission path, only an insertion period of 3 symbols is required, and a long period like the training signal in the conventional method is not required.

FIG. 2 is a diagram showing an example of the configuration of a selective fading distortion compensation circuit used on the receiving side in the present invention. In the figure, reference numeral 21 is an impulse detection judgment circuit for detecting the impulse 13 sent from the transmission side and judging fluctuations in amplitude and phase due to selective fading of the impulse, and 22 also includes information from the impulse detection judgment circuit 21. The selective fading distortion correction circuit estimates and corrects the distortion due to the selective fading at the timings of all the symbols of the information symbol 11 by interpolation processing such as the least square method. The selective fading distortion correction circuit 22 is configured by a known method such as delay equalization or maximum likelihood determination.

The operation of the selective fading distortion compensation circuit of the present invention based on the configuration example shown in FIG. 2 will be described in detail below with reference to FIGS. 2 and 3 using the data of the transmission format shown in FIG. The data having the transmission format according to the present invention as shown in FIG. 1 sent from the transmitting side is input to the impulse detection judgment circuit 21 and the selective fading distortion correction circuit 22. The impulse detection determination circuit 21 detects the non-transmission section 12 in the transmission data and synchronizes with the impulse 13.

FIG. 3 is a waveform diagram showing the effect of selective fading on the impulse of the present invention. The impulse 31 transmitted from the transmitting side as shown in FIG. 3 (A) is affected by the selective fading on the mobile radio channel, and the preceding wave component 32 of the impulse and its component 32 are received at the receiving side as shown in FIG. 3 (B). The wave is dispersed in the delayed wave component 33. Therefore, by setting the length m symbols and n symbols of the non-transmission section as described above, the delayed wave component generated from the information symbol 11 arranged before the impulse interferes with the impulse 13 on the receiving side. And the delayed wave component 33 does not interfere with the subsequent information symbol, the amplitude and phase fluctuations of the preceding wave component 32 and the delayed wave component 33 of the impulse 13 on the receiving side (that is, the transmission line impulse response). Since correlation can be directly obtained, the conventional correlation calculation is unnecessary.

In the selective fading distortion correction circuit 22,
By accumulating the information symbols 11 for one cycle or several cycles and performing interpolation processing using the amplitude and phase information of the preceding wave component 32 and the delayed wave component 33 from the impulse detection determination circuit 21, each symbol of the information symbols 11 The amount of fluctuation of the amplitude and phase of the preceding wave component 32 and the delayed wave component 33 at the timing is estimated. The distortion is compensated by performing a calculation for estimating and correcting the distortion due to the selective fading included in the information symbol 11 based on the estimated values of the fluctuation amounts of the amplitude and the phase.

As a method of compensating for the above distortion, for example, a decision feedback type delay equalization method of reproducing a delayed wave component due to an already determined information symbol and canceling it out from a received signal can be applied. Further, as another example, the reception eye pattern including the delayed wave component is obtained in advance on the reception side, and the Euclidean distance of the reception signal is obtained to determine the information symbol sequence that gives the minimum Euclidean distance as the determination output. The likelihood determination method can also be applied.

[0012]

As described in detail above, according to the present invention, since the impulses and non-transmission intervals inserted between information symbols at a constant period are short, the transmission efficiency is less deteriorated and the impulse response of the transmission path is small. Since it is possible to realize selective fading equalization that does not require correlation calculation in obtaining, it is extremely effective in performing high-speed data transmission.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a data transmission format according to the present invention.

FIG. 2 is a configuration example diagram of a selective fading distortion compensation circuit according to the present invention.

FIG. 3 is a waveform diagram showing an example of the effect of the selective fading of impulses of the present invention.

FIG. 4 is a diagram showing a configuration example of a conventional data transmission format.

[Explanation of symbols]

 11 information symbol 12 non-transmission section 13 impulse 21 impulse detection judgment circuit 22 selective fading distortion correction circuit 31 transmission impulse 32 preceding wave component of reception impulse 33 delayed wave component of reception impulse 41 information symbol 42 training signal

Claims (1)

Claim: What is claimed is: 1. A transmitter transmits a transmission signal in which a impulse signal having a non-transmission section of a predetermined length before and after is inserted in a transmission data at a constant cycle from the transmission side. The impulse signal is detected from the transmission signal received via the line, and the amplitude information and the phase information of each of the preceding wave component and the delayed wave component of the impulse signal generated by the selective fading of the wireless line are determined. , The selective fading distortion at the timings of all the symbols in the transmission data is estimated by the interpolation process by the amplitude information and the phase information, and the selective fading is performed by the delay equalization method or the maximum likelihood determination by the estimated value. A selective fading distortion compensation method adapted to correct distortion.