Research On Cooperative Communications Using LDPC In The Relay Environment

In wireless communications system, diversity is a kind of effective technique to resistmulti-path fading and channel interference. Cooperative relay is mainly based on the nature ofbroadcast, which can reduce the consumption of energy, bandwidth of the terminal, and canalso significantly improve the spectral efficiency, throughput, and the capacity of the system.LDPC codes come to be one of the best coding technologies because of their low-complicityiterative decoding algorithm and capacity approaching performance, and they attract more andmore in recent years.Firstly, the basic principle and basic protocol of collaborative communication, LDPCcodes’principle are introduced.Secondly, based on relay communication theory and relay communication model, LDPCcode and coded cooperation diversity are combined. It discussed the single-relay and multiplerelays. Then it discussed the best relay node position in the AF mode and DF mode.Finally, the thesis combines the merit of amplify-and-forward (AF) relaying anddecode-and-forward (DF), proposed the hybrid and forward cooperative model based onLDPC codes. When the channel state is bad, the relay uses decode amplification forwardmode, and when the correctly decodes completely, the relay switches to decode forward mode.The simulation results show that performance of LDPC codes coopera tive model based on thehybrid-and-forward is superior to the AF mode and DF mode.