Efficient Time-Based Topology-Dependent Scheduling for Radio Packet Networks∗

In Radio Packet Network (RPN), unconstrained transmission may lead to collision of two or more packets. Time Division Multiple Access (TDMA) protocol is a common used protocol to schedule collision-free transmission for such networks. TDMA transmission allows a number of users to access a single radio channel without interference by allocating unique time slots to each user. In TDMA network, time is divided into frames and a frame consists of time slots. For fully connected networks where each node is a neighbor for all the other nodes, each node should assign a different time slot in TDMA frame to transmit in it to have collision-free transmission. Typically, those time slots are ended by guard times for propagation delays. Those guard times are fixed for all time slots regardless the actual needed propagation delays. In this paper, we propose a topology-dependent algorithm that automatically schedules collision-free channel access and specify the time instant when a node is to send a packet. We use variable guard times, instead of the fixed ones, calculated using the actual needed propagation delays between sources and destinations. We show that with such scheduling algorithm, a 90% saving in the original guard times is achieved.