ASAND: Asynchronous Slot Assignment and Neighbor Discovery Protocol for Wireless Networks

Slot assignment is crucial for time-multiplexed channel access schemes. All existing approaches for slot assignment assume that the network nodes are synchronized with high precision, which is costly to maintain. We propose a novel slot assignment protocol which does not rely on time synchronization among nodes in the network. As a byproduct, each node discovers its neighbors along with a local schedule of their channel access times, which is a crucial piece of information for many networking protocols. We describe our approach, present the Asynchronous Slot Assignment and Neighbor Discovery protocol (ASAND), and then provide the OPNET Modeler implementations and simulation results for our protocol. ASAND works in a completely distributed manner and assigns a time interval for each node in the network which is collision-free in its 2-neighborhood. Hence, it eliminates the collisions between neighbor nodes and the hidden-terminals without any explicit time synchronization in the network.