Research On The Combination Of OVCDM And Cooperative Communications

Cooperative Communications, one of implementation of MIMO, can increase thetransmission reliability by using cooperative diversity. Traditional high-order modulation canincrease the spectrum efficiency, but it also increases the system complexity and decreases thesystem performance. Overlapped Code Division Multiplexing (OVCDM) is a convolutioncode in complex domain which combines coding and modulation. It can obtain high spectrumefficiency with low order modulation and get some coding gains. This paper mainly studiesthe combination of OVCDM and Cooperative Communications. The works are as follow:(1) Cooperative Communications, OVCDM coding theory and Viterbi decodingalgorithm are described briefly, and the simulation and analysis of Amplify and Forward (AF),Decoded and Forward (DF) strategy and OVCDM system are given.(2) Research the strategy of combination of OVCDM and AF, DF, respectively. Simulateand analyze the performance of the combined system. The experiment results show that thecombined system can obtain higher spectrum efficiency than the traditional CooperativeCommunications.(3) Research the strategy of concatenated OVCDM with AF, DF respectively andsimulate and analyze their performance. The experiment results show that, the concatenatedOVCDM AF and DF system can get a higher performance compared with thenon-concatenated ones; Because of the efficiency of the outer code, the OVCDM DF systemcan better adjust to the channel between source and cooperative node; The concatenatedOVCDM Cooperative Communications system can perform well only in middle and highSNR situation when comparing with the traditional concatenated ones.(4) Research the combination of OVCDM with Cooperative Network Coding andsimulate and analyze the combined system. The experiment results show that the combinedsystem can get a better performance.