Signal detection for cooperative cellular systems with 4 relay nodes under imperfect synchronization

Signal detection for an asynchronous 4-relay-node cooperative cellular system using Distributed Space-Time Coding (DSTBC) on the uplink is investigated in this paper, where co-channel interference (CCI) limits the system capacity more than thermal noise and inter-symbol-interference (ISI) caused by the imperfectly synchronized cooperating relays greatly degrades the system performance. Most research has so far focused on applying DSTBC with 2 relay nodes to cooperative communications on individual links rather than in a cellular environment, and assumed perfect synchronization among all the relays. This paper derives a signal detector based on parallel interference cancellation and successive interference cancellation to remove the CCI and ISI within an asynchronous cooperative cellular system. Simulation results demonstrate the effectiveness of the proposed scheme in suppressing the impact of co-channel interference and imperfect synchronization.