The Research Of Power Allocation Algorithm In Cooperative Communication Systems

With the development of wireless communication, speech communication is no longer the only business people need. The higher data transmission speed and better communication quality are required in the services. According to the characteristics of wireless channel fading, the mobile terminal size, researchers have proposed the cooperative communication technology, With the introduction of cooperative relay, a single antenna mobile users can mutually adjacent cooperative forwarding information, form a virtual multiple-input multiple-output (Multiple Input Multiple Output. MIMO) system, provides a feasible scheme for the problem that mobile terminal unable to install multiple antennas due to size or propagation environment can not support the MIMO systems, Information in Cooperative communication is transmitted by the source and relay nodes, so the source node and the relay power allocation scheme for cooperative communication between nodes system has important influence and significance. This paper is mainly on the aspects of power allocation of cooperative communication.This paper first describes the research status of coordinated communication and related technologies, analyzes the amplify-and-forward relaying protocol (Amplify and Forward, AF) protocol and decode-and-forward (Decoded and Forward. DF) protocol. Then use the system symbol error rate (Symbol Error Rate, SFR) as the criterion, in single relay model separately on the SER performance of AF protocol and DF protocol are analyzed, obtained in the M-PSK and M-QAM modulation of the SER asymptotic approximation expression, and according to the asymptotic solution of the optimal power allocation for SER minimizations based on, and simulated by MATEAB, analyzes the different relay protocol, different modulation of the power and the optimal power allocation scheme and simulation. Analysis and simulation show that, the optimal power allocation outperforms the equal power allocation; cooperative DF protocol performance is not worse than AF cooperative agreement, modulation and channel quality have a significant effect on the performance of different the complexity of cooperative agreement; The complexity of AF is lowwer than that of DF protocol. Finally, this paper gives a multi-node cooperative communication systems in the AF protocol based on the power allocation of SER standards. According to the results of analysis, put forward the optimization strategy of a SER for the objective of minimizing the adaptive relay selection and power allocation based on the signal-to-noise ratio and channel quality, election relaying protocol, different the relay node number and modulation. The simulation results show that system performance optimization scheme has greatly improvements compared with the fixed by a cooperative protocol.