With the rapid growth of multimedia services, wireless communications require higher data rates and more reliable transmission link. One of the solution is Multiple-input multiple-output (MIMO) antenna systems yielding multiplexing and diversity gains without increasing bandwidth and power. But the size of the mobile devices , requirement on the distance between antennas, the propagation environment, hardware complexity and cost may pose limitations on the deployment of MIMO sytems. These limitations of MIMO systems can be overcome by Cooperative Communication. A cooperative communication system is a system where the conventional STBC designed for co-located MIMO system is implemented via the relay nodes in a distributed manner. Relay nodes are located at different places and each has its own local oscillator. In order to achieve the original designed diversity gain, synchronization must be done among the source node, relay nodes and the destination node which could introduce a significant overhead. The signals as broadcasted from the source are received by the R relays distributed in space. These signals are cooperatively transmitted as Distributed Space Time Block Codes(DSTBC) using the linear dispersion structure to the receiver. The cooperative communications network are basically asynchronous in nature. To deal with the timing errors among the relay nodes, the codewords are padded with guard intervals, so that the adjacent codewords do not overlap with each other. The padding length must be longer than the maximum delay.