| Cooperation communication is a hot research topic in wireless communication presently. As one of its key technologies, cooperative diversity can realize a virtual MIMO system through relay macro cooperation based on the relay channel theory and therefore expand the application scenarios of MIMO system achieving space diversity gain and improving the reliability of the wireless communication. As a new research field, cooperative diversity has very broad application prospects. It can be applied to cellular mobile communication system, wireless Ad hoc network, wireless Mesh network, wireless LAN, wireless sensor network and other occasions.A new diversity technology—cooperative diversity are analyzed, and several cooperative diversity schemes are realized based on binary modulation and higher modulation order. The cooperative diversity schemes in binary modulation system are analyzed firstly with the emphasis on the coded cooperation and its performance. In coded cooperation, cooperative coding between users is used instead of the repetitive coding before and every group of codeword is fragmented into segments and each segment is transmitted over independent fading channel respectively. For fast Rayleigh fading channel, space-time coding is introduced called space-time cooperation. Theoretical analysis and simulation show that the system performance is improved further. However, coding in binary modulation cooperation system may result in bandwidth expansion. To solve this problem, bit-interleaved coded modulation technology is brought in cooperative diversity and two bandwidth-efficient coded cooperation schemes are realized based on RCPC and Turbo coding respectively. Simulation results show that for slow Rayleigh fading channel, the fraction of repeated codeword and higher modulation order can be used for bandwidth-performance tradeoff. As a result, performance of the whole system is improved and the bit error probability is decreased with guaranteed bandwidth efficiency. |
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