Research On A Distributed Network Of Wireless Two-way Multi-hop Differential Transmission Scheme

With the rapid development of wireless multimedia services and a sharp increase in applications, the capacities of wireless cooperative communication systems are also facing unprecedented challenges.In this situation, distributed multi-antenna technology was proposed. In recent years, various communication nodes located in different geographical locations are used to structure suitable "virtual multi-antenna" systems. Wireless cooperative communication systems which can corporately achieve information exchange have emerged then. At present, these wireless cooperative communication systems mainly adopt non-coherent and coherent communication to communicate. Because the non-coherent communication system does not need to estimate channel state information, it is widely applied in some complex multi-hop wireless communication system, especially in the differential transmission. The study of two-way differential transmission scheme is still in its infancy, and the two-way multi-hop differential transmission scheme to realize the remote communication is rarely reported in the high-speed mobile communication environment. For this issue, the thesis based on a two-way multi-hop transmission model presents a two-way multi-hop differential transmission program which can achieve long-distance communication in the two-way wireless distributed networks.In the multi-hop differential transmission scheme of two-way wireless distributed networks, what the two end nodes transmit are respectively differentially encoding information symbols. The relay nodes of the edge position only amplify and forward the information it receives from the upper stage and transmit until the information reach the relay nodes in the intermediate position. The received signal from the first two stages is first carried out through a Hadamard product of the operation by relay node in the intermediate position. Cyclic delay processing is conducted after it is blended into an information symbol. Then amplify and forward the message in the reverse manner to the relay node of the adjacent edge position. In the process of reverse transmission, relay node in the edge position only amplify and forward the information it receives from the previous phase until the signal reaches the corresponding terminal node.Derivation formula analysis confirmed the feasibility of multi-hop differential transmission scheme of two-way wireless distributed network. Through MATLAB simulation, BER performance of transmission scheme is presented under different experimental environments. The results show that multi-hop differential transmission scheme of two-way wireless distributed network the thesis proposes, it is possible to increase the signal transmission distance because of the increased number of slots the signal may span. As a result of differential encoding, no estimate channel state information. As the cyclic delay diversity technique is introduced, the detection complex degree of the receiving end will not increase when the number of relay nodes increase. And the scheme can be utilized in the scenarios with any number of relay nodes.