The Distributed Wireless Communication Coordination Fountain Decoding Technology Research

Fountain Codes are a new class of erasure codes, which can generate infinite encoded symbols and can control rate flexibly. In implementation, fountain codes adopt a simplex mechanism of asynchronous transfer, which possesses high-efficiency and low-delay, adapts the time-variant of channel easily. In addition, its complexity of encoding and decoding is low and symbol packets do not require to be continuous. Therefore, it is very consistent with characteristics of deep space link easy to break. But performance of fountain codes greatly affected by the code length, the good performance of fountain codes must be used longer code length. In the deep space communications, the device in relays and stars is source energy limited. It is necessary to design short frame length with good performance of fountain codes. Under this basis, we extend cooperative communications concept to long-distance on the deep space channel code, thus arise the concept of distributed fountain codes. It is the fact that system performance can be improved by distributed coding. In order to improve the performance of the cooperative communications system, the distributed LT codes are designed in this paper.In this paper, firstly we introduce fountain codes and cooperative communication background and encoding and decoding process of LT codes that is a kind of good performance fountain code in detail. Extend simulations are given for LT codes with various code lengths under the different delete the probability. For relay transmission LT codes can find the new application. After introducing fundamentals of distributed foundtain codes, including deconvolution of LT codes, the encoding rules at the source and consolidation rules at the relay, the distributed LT codes for the scenarios in which two sources or four sources communicate with a common sink through a relay are described in detail. Analyzing and comparion results of LT code, two-source distributed LT codes and four-source distributed LT codes are provided. The results show that distributed LT codes can offer a significant performance improvement. At last, we compare the transmission efficiency of HARQ error control system with those of system with LT codes.