A Novel Cooperative MAC Protocol for WSN Based on NDMA

A novel MAC protocol based on network-assisted diversity multiple access (NDMA) is proposed for wireless sensor networks (WSN) in this paper. We view WSN as a spatially distributed antenna with antenna elements linked via the wireless channel. The proposed scheme exploits cooperative diversity to overcome multipath fading and selects relay nodes according to a new predetermined order that can effectively limit the times of retransmission. In the slots following the collision, a set of nodes designated as relays will cooperate with source nodes and destination node to form virtual antenna array and retransmit the signals that they received during the collision slot. By processing the originally collided packets and the signals forwarded by the relays, the destination node can recover the original packets. The proposed scheme also considers some practical problems in WSN, i.e. throughput efficiency, fairness, channel condition, which enable WSN to be robust to the wireless channel and achieves higher throughput than existing techniques that allow for multiple packet reception (MPR)