Channel coding method for enhancing transmission quality of fountain code on wireless channel

Abstract

The invention discloses a channel coding method for enhancing the transmission quality of a fountain code on a wireless channel, which comprises the following steps of: when coding an IBRC channel, sequentially displacing input code words firstly by an IBRC coder circularly through taking each element in two displacement vectors as the amplitude of the circular displacement of each time sequentially, then carrying out modular two addition on all the obtained code words after displacing circularly to obtain two code words totally, afterwards cascading the two code words to obtain coding code words, modulating by using BPSK and transmitting; when decoding the IBRC channel, dividing the received code words into a front section and a back section after carrying out BPSK demodulation on the received code words by an IBRC decoder, then carrying out modular two addition, afterwards carrying out reverse circular displacement, determining whether IBRC code words are erroneous in the transmission process or not on the basis of the code words obtained after displacing circularly, and outputting the code words directly if the IBRC code words are not erroneous; otherwise, setting an erroneous bit number sequentially within a certain range, decoding under the setting, and outputting a decoding result if the decoding is successful; and if the set erroneous bit number is still not decoded successfully after the set erroneous bit number samples all integers in the range, outputting all-zero code words by the IBRC decoder.

Description

technical field [0001] The invention relates to a fountain code and a channel coding method of a wireless channel, belonging to the field of wireless data transmission. Background technique [0002] After LT codes and Raptor codes were proposed and studied as two implementation forms of fountain codes, fountain codes proved to be a data encoding method with excellent transmission performance and low complexity implementation process, so fountain codes were also It is regarded as an ideal means of transmission for realizing large-scale data broadcasting, and has been listed as a specific relevant standard of 3GPP and DVB-H. The key to this technology is to generate an infinite number of encoded codewords called LT codes from K source data packets through the core LT encoder, and the LT decoder at the receiving end only needs to correctly receive any code words slightly larger than K The N LT codes of N LT codes can recover about K source data packets. [0003] The tradition...

AI Technical Summary

Problems solved by technology

[0004] However, only in a wired environment, the lack of fountain codes does not necessarily have the good performance on the erasure channel mentioned earlier, that is because the wireless channel is not an erasure channel but an interference channel, so the receiving end receives in the wireless channel The LT codes may contain errors

According to the encoding method of the LT encoder, once the wrong LT codes enter the LT decoder, a series of LT decoding errors (error propagation) will be caused, and the final source data packet cannot be completely recovered correctly.

Although an ordinary Forward Error Correction Encoder (FEC) can be cascaded behind the LT encoder at the sending end to channel encode the generated LT codes, and then perform FEC decoding on the interfered data packets received on the channel through the receiving end , in order to reduce the possibility of the LT decoder at the receiving end receiving wrong LT codes to a certain extent, but in an environment with poor channel conditions, the limited error correction capability of FEC cannot cope with interference caused by noise or fading. When the receiving end When the received data packet contains too many errors caused by channel interference and cannot be recovered correctly, the ordinary FEC decoder will decode the data packet into a wrong LT code, and ultimately cannot effectively prevent the error LT codes enter the LT decoder

To sum up, even if ordinary FEC is used for auxiliary channel coding, it still cannot bring enough improvement to the transmission performance of fountain codes on wireless channels, so it is necessary to find LT codes that can effectively prevent errors from entering the LT decoder A special channel coding method to ensure that the fountain code can perform reliable data transmission on the wireless channel

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