Throughput-delay characteristics of OCUM protocol for media access in multihop wireless networks with buffers

Abstract

In this paper, we present the throughput and delay performance of a busy tone-based media access protocol in wireless networks with buffers at each node for the queueing of messages. Partially connected static topologies with a finite number of nodes that are globally synchronized to the slot duration are considered. Each node has unlimited buffer resources for transit messages and limited buffer capacity for newly arriving entry messages. The input buffer limiting policy rejects new message arrivals when the total number of queued messages (including entry and transit messages) exceeds a finite buffer threshold L at each node. Messages are serviced on a first-come-first-served basis. Simulation results for fully connected, ring, bus, multiconnected ring, square lattice and other arbitrary topologies are presented. The protocol offers constant throughput of the order of 0.8–0.9 at high arrival rates in a fully connected network. Throughput is found to improve at low arrival rates as the value of L is increased. However, the improvement becomes marginal for L > 4. For other multihop topologies like ring, bus, multiconnected ring and square lattice, the throughput performance improves beyond unity due to spatial reuse.