development of relay selection algorithms in cooperative communication for ad hoc network

Abstract

To address the limits in attaining MIMO gains in future wireless networks, new techniques beyond traditional point-to-point communication needs to be designed. Nodes present in the network can cooperate with one another to support distributed transmission and processing of the information. The node that cooperates with the source to transmit the information generated by the source is known as relay node. Cooperative communication is a new concept that generates independent paths between the source and the base station by employing a relay. Relay channel fades independently from that of the direct channel between the source and the destination, as the relay will be placed several wavelengths away from the source. This develops a full rank MIMO source- destination channel. Cooperative communication can be applied to wireless adhoc networks, where the relay node cooperates between source and destination nodes. newlineThe issue addressed in the first algorithm is about improving the quality of the audio, by incorporating a relay between source and destination, where the relay uses decode and forward technique before forwarding the information to the destination. Destination applies Maximal ratio combining(MRC), to combine the signal received from the source and the relay. This concept is called Cooperative communication. A location aware decentralized relay selection strategy is proposed in this work for a wireless ad-hoc network. Existing Request to sent(RTS) and Clear to send(CTS) frames of IEEE 802.11b are modified to incorporate the location information of the source and destination respectively. A new control frame called Ready to forward(RTF) is proposed for announcing the selected node as the relay node. newlineG.711 audio codec is considered to process the audio data. Received audio data is encoded and 4/16 QAM modulated. Propagation model considered here is Rayleigh faded channel having a uniform power delay profile and path loss depends on the distance travelled by the information. Rayleigh faded signal is add