Superposed CDMA Relay Cooperation in Wireless Sensor Networks

This paper adresses the problem of cooperation application in an existing non-cooperative wireless sensor network. Sensors are low-energy and low-data rate devices. They transmit small independent individually-encoded information packets to the same destination. The cooperation scheme is based on a product code distributed among sources and relays and turbodecoded at the destination. We propose a system where a relay code division multiple access-based transmission is superposed with the sources time division multiple access-scheduled transmissions. A relay interference cancelation algorithm is defined and the whole system is simulated considering source-destination and relaydestination AWGN channels. The source-relay channel is assumed error-free. An optimized energy allocation between the sources and the relay is extracted from simulations.