Distributed Beam Forming Techniques for Dual-hop Decode-and-Forward based Cooperative Relay Networks

Abstract

In this paper, it has been proved that the transmission rate can be increased substantially by alleviating cochannel interference by use of beamforming techniques at relay stations. In this setup, the downlink transmission segment is taken into consideration from the Base Station (BS) to two Mobile Stations (MS). The data is transmitted concurrently through two Relay Stations (RS) using the same frequency channel. It is assumed that the RSs use decode-and-forward (DF) strategy. In this technique of beamforming, pre-coding vectors are used at the RS to alleviate co-channel interferences. Due to this strategy, each user will be able to get its own data sans interference. Two pre-coding techniques which incarnate two different transmission protocols have been proposed. Simulations results show that such type of schemas outperforms their counterpart brethren schemas.