The Relay Routing Mechanism In The Wireless Cooperative Communication System Research

Due to the broadcasting characteristic brought by wireless medium, how to employ space diversity efficiently has become a primary challenge for wireless cooperative communication system. The design of relay routing selection scheme plays an important role for end-to-end network performance. Aiming at the path selection variety and data redundancy issues caused by space diversity over the network, this thesis focuses on improving the end-to-end data transmission, network throughput and decreasing the network delay by developing multiple relays routing selection scheme. The main works are as follows:Firstly, to solve the complicated channel environment problem caused by broadcasting characteristic of wireless medium, an opportunistic multiple relays selection scheme based on the equivalent channel gain is proposed over the cluster-by-cluster transmission model. Bit error rate is used to obtain the equivalent channel gain derivation of formula, which reflects the overall channel quality of multiple wireless links. The relay nodes calculate the threshold of equivalent channel gain by outage probability. To select the relays with better performance, the recursive method is employed in the selection process, and the linear network coding is also used to decrease the data redundancy at the relays. Moreover, to ensure the balanced employment of network resources, the number of relay is quantified via the threshold and the number of encoded packets needed by destination.Secondly, according to the concurrency and randomness of data transmission over the network, a coding and interference-aware relay routing selection scheme is proposed, and the data transmission model of multiple sources and multiple destinations is modeling. According to the traffic pattern and network coding constructure, the condition of network coding and interference among nodes are defined. Focus on increasing the network throughput and decreasing the network delay, the encoding gain, degree of encoding and the degree of interference are used to formulate the relay routing selection metric. And the best path over the network is selected with the metric. Finally, performance evaluations of the proposed equivalent channel gain based opportunistic multiple relay routing selection scheme and coding and interference-aware relay routing scheme are taken under Matlab and NS2simulator respectively. The performances of end-to-end data transmission, network throughput and delay are analyzed, and the results show the reasonability and efficiency of our proposed schemes.