Relay No-linear Precoder in Asynchronous Cooperative Systems with Insufficient Cyclic Prefix
Liu Pin · Computer Technology and Development · 2015
In the asynchronous cooperative OFDM system,Orthogonal Frequency Division M ultiplexing( OFDM) technology is applied to combat the time delays from the relay nodes. Channel from relay nodes to the destination node are treated as multipath channel,when the Cyclic Prefix( CP) is not less than time-delay length,Inter-Symbol Interference( ISI) caused by the time delay can be effectively avoided. Actually,the time delays from relay nodes may vary and depend on a particular scenario in a cooperative system,thus time-delay cannot be know n in advance,and adding cyclic prefix will reduce code transmission rate. Therefore,it is necessary to research transmission scheme for asynchronous cooperative OFDM system with insufficient CP. However,when the CP length is less than the length of the time-delay,inter-symbol interference cannot be completely eliminated. In order to solve this problem,design a scheme of no-linear precoder in relay node. Simulation results show that the scheme of no-linear precoder in relay node can significantly low er bit error rate,improve the utilization rate of system bandw idth,and prove the performance of the scheme is better than the scheme of decision feedback equalizer in receiver.