A Distributed MAC Protocol for Multi-Packet Reception Wireless Networks

In this paper we propose a decentralized medium access control (MAC) scheme to coordinate the access of multiple transmitters adopting a multi-packet reception (MPR) physical (PHY) layer. MPR receivers are able to decode multiple transmissions, and depending on the technique adopted at the PHY-layer, there is an optimal number of simultaneous transmissions that maximize the number of packets successfully decoded in a simultaneous way. The proposed MAC scheme admits an MPR PHY-layer and is divided in two stages. In the first one the nodes indicate their willingness to transmit, while in the second one they jointly transmit. Adopting a generic model for the PHY-layer, we characterize the throughput achieved by the proposed MAC when both MAC and PHY layers are considered. The formal characterization of the throughput is then used to optimize the duration of the first stage of the MAC scheme in order to optimize the throughput. In this way, the number of transmitters is regulated to optimize the cross-layer operation, taking into consideration the features of the MPR PHY-layer and the maximum performance achieved with the proposed MAC design. Several results obtained through simulation are presented, which validate the numerical results obtained with the proposed characterization. The proposed scheme is a first step to develop MAC protocols specifically designed to distributed MPR systems that operate in a cross-layer and improve the exploitation of current and future MPR techniques proposed for the PHY-layer.