Green Cooperative Transmission Scheme for Estimate-and-Forward Relay Based Wireless Communication Systems

Energy efficiency in wireless communication is a contemporary research area especially in cooperative communication systems as it can be effectively used in cellular communication, vehicular access networks and sensor networks. This paper addresses power savings in estimate-and-forward (EF) relaying system which is a simplified version of the decode-and-forward relaying technique. EF relay does not detect any error in the decoding process but rather forwards an error-containing version of the signal to the destination. The destination combines the error-containing signal from the relay with the signal from the source to realize cooperative diversity. This paper addresses a power efficient relay communication by using a power limiter at the relay. We propose a novel power-adaptive scheme at the relay for an EF relaying system. It is shown that a large portion of the transmit power is wasted by the clipper at the diversity combiner of the destination in the existing scheme. We propose to use of a power limiter at the relay to control the relay transmit power according to the error status of the source-relay link. We compute the average waste of the proposed scheme and show that it outperforms the the power waste of the existing scheme with negligible BER degradation. We further propose to reuse the saved power at the source to improve the BER performance of the system.