Research Of Full-rate Multi-hop Wireless Cooperative Relay Transmission Scheme

With the continuous progress of wireless communication technology, the MIMO (Multiple Input Multiple Output) technology and OFDM (Orthogonal Frequency Division, Multiplexing) technology, which have made a significant breakthrough in the development, have become two major technologies of constructing and popularizing the4G network, and will demonstrate broader application prospects. Because the application of MIMO technology is limited by user antenna and transmission channel conditions in practical scenarios, the theory is often difficult to realize in practice. Cooperative communication is aimed at resolving the difficulties of MIMO in practical applications and improving the communication capacity and performance.The design of reasonable space time frequency coding scheme, is the key of the cooperative communication network to obtain diversity gain, to improve system performance, and to reduce detection complexity. The construction of the appropriate system transmission model is an important component of the cooperative communication technology applied to the actual scenarios. Therefore, researchers have studied cooperative communication with a particular focus on the design of coding and transmission scheme in these years.This thesis will study the FDFR (Full Diversity Full Rate) space-time coding scheme based on the LCF (Linear Complex Field) pre-code, and space-frequency coding scheme based on the CDD(Cyclic Delay Diversity), then will rationally combine the idea of the two coding scheme, design for cooperative communication network space time frequency coding, in order to improve the bit error rate performance, to reduce system redundancy, while obtaining full diversity gain of the system and increasing the transmission rate. On the basis of analyzing the application of the full-rate full-diversity coding scheme in the traditional three-point model and the dual-link two-hop transmission model, this thesis will design and propose a full-rate wireless cooperative relay transmission scheme with low detection complexity based on the multi-hop and multi-link cooperative communication network.The scheme will use the OFDM technology, and take the transmission data of the source node pre-coded by a reasonable simplified LCF. Then the pre-coding data will be sent one by one in three consecutive time slots, the relay nodes will amplify the received data and transmit them to the next node with cyclic delay form until the data are received by the destination node. The thesis will take the theoretical analysis and simulation to prove the advantages of the scheme which adopted the full-rate space-time frequency coding and transmission models. The scheme will achieve a reasonable extension of the transmission link and relay number, become capable of obtaining full diversity gain, while significantly reducing the detection complexity by the receiver structure of the destination node It will also achieve the long-distance transmission of the signal in the cooperative communication network in the actual scenarios.