CN1093724C - Method of estimating radio channel bit error rate in mobile digital communication system - Google Patents

Abstract

A method for estimating the channel bit error rate in a digital communication system. After the demodulation and decoding steps are performed at the channel receiving end, encoding corresponding to decoding (such as Farr code encoding) is performed and the encoded signal sequence N, compared with the signal sequence M after demodulation and before decoding, so as to calculate the bit error rate of the wireless channel as follows:

This estimation method is simple and clear, and basically does not occupy system resources. It does not need to perform a transceiver loopback test on a fixed test pattern, and can flexibly estimate the channel communication quality by using various channel coding and decoding characteristics.

Description

Estimation Method of Bit Error Rate of Wireless Channel in Digital Mobile Communication System

technical field

The invention belongs to the technical field of communication, and in particular relates to a method for estimating the bit error rate of a wireless channel in a digital communication system.

Background technique

In communication systems, the measurement of channel quality such as bit error rate is an important basis for judging system performance. In digital communication systems, the commonly used channel test method is the transceiver loopback test, that is, the sending end sends out a fixed test pattern, and the receiving end compares the received test pattern that has passed through this channel with the original test pattern. The bit error rate of the current channel can be obtained. However, in real-time communication, this test method is obviously very limited. For example, it is impossible to interrupt the ongoing conversation in order to test the bit error rate of the channel, and it is impossible to insert a large number of useful information bits into the useful information bits for channel testing. Test bits. In short, this traditional test method causes serious waste of system resources and adversely affects system performance.

Contents of the invention

The object of the present invention is to provide a method for estimating the bit error rate of a wireless channel in a digital mobile communication system. This method can overcome the shortcomings of the prior art, and can directly receive the error rate from the receiving end without sending a fixed pattern from the sending end. Useful information to estimate the channel bit error rate.

The object of the present invention is achieved by constructing a method for estimating the bit error rate of a wireless channel in a digital mobile communication system. The obtained signal sequence N is compared with the signal sequence M after demodulation and before decoding, so as to calculate the bit error rate of the wireless channel as follows:

Wherein, the error correction range of the coding method adopted in the coding step is larger than the possible bit error rate of the estimated bit error rate channel, and the coding method is based on the Farr code method.

The method for estimating the bit error rate of the wireless channel in the digital mobile communication system provided by the present invention is a concise and effective test method that basically does not occupy system resources, and has been tested in practice. There are broad application prospects in the field of communication. In other words, the method of the present invention has obvious flexibility compared with the traditional channel bit error rate measurement method, and it is characterized in that it does not need to carry out the sending and receiving loopback test on the fixed test pattern, that is, it can use the characteristics of various channel codecs to flexibly estimate out communication quality.

Description of drawings

Fig. 1 is a schematic diagram illustrating the signal data process when the method of the present invention is applied in the GSM system.

Detailed ways

The origin, characteristics and application of the method of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The method for estimating the bit error rate of the wireless channel in the digital mobile communication system provided by the invention is applicable to all digital communication systems. Now take the GSM digital cellular communication system as an example to describe in detail.

As shown in Figure 1, in the GSM system, information is transmitted in frames, and the digital information A received by the base station is demodulated by the demodulator 100 and then converted into demodulated information M, which is sent to the channel decoder 200 to obtain the decoded information The signal sequence B of code, the core that the method of the present invention carries out communication quality estimation to the uplink channel is to the result (signal sequence B) of channel decoding and then do the encoding processing corresponding to described decoding by encoder 300 again, through this Comparing the coding result (signal sequence N) with the original received sequence (signal M) of the decoder 200, the bit error rate of the current frame without channel coding (200) can be calculated, and the result can be extended to a wireless channel communication quality.

A prerequisite for making this method of the present invention effective is to assume that the result of decoding is the completely correct result we expect. This assumption is obviously reasonable for codes with strong error-correcting capabilities. Here, we might as well take the Fire codes that are commonly used in digital communication as examples to illustrate them.

Fire code itself is a kind of linear block code, which is characterized in that as long as the error is within its error correction range, it can definitely ensure that the decoding result is completely the expected correct value through error detection and error correction. Then the correct decoding result can be used as the basis for comparison with the original input information received by the decoder after being encoded by Fire code. By comparing the two sequences M and N, the number of different symbols can be obtained, and the result of dividing the total number of symbols of this sequence by the number of different symbols is the bit error rate of digital information passing through this wireless channel . Here, the input sequence of the decoder is M, and after the decoding is completed, the sequence obtained by encoding the decoding result again is N. Then, the formula for calculating the bit error rate of the wireless channel is as follows:

Obviously, as long as the channel bit error rate is within the error correction range of the Fire code, we must be able to calculate the current channel bit error rate in real time in this way.

Obviously, this scheme is extremely valuable in digital wireless communication. Taking the GSM cellular system as an example, the quality of the channel is an important basis for judging whether handover is required. In fact, we can only obtain the communication quality of the downlink channel through the channel quality information reported by the mobile phone. It is impossible to calculate its exact channel bit error rate in real time. The above method provided by the present invention effectively solves such problems.

Claims (2)

1. A method for estimating the bit error rate of a wireless channel in a digital mobile communication system, characterized in that, after the channel receiving end performs demodulation and decoding steps, it also encodes, and the encoding method adopted in the encoding step corrects The error range is greater than the possible bit error rate of the estimated bit error rate channel, and the encoded signal sequence N is compared with the signal sequence M after demodulation and before decoding, so as to calculate the bit error rate of the wireless channel as follows 2. The method for estimating channel bit error rate in a digital communication system according to claim 1, characterized in that said encoding step is performed based on a Fire code encoding method.

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