Poster Abstract: Formalizing Packet Level Incoordination in IEEE 802.11 Ad Hoc Networks: 1-Hop Broadcast Performance Analysis

Assume a communication scenario in wireless ad hoc and sensor networks where each node periodically sends out status information as a 1-hop broadcast to inform neighboring nodes. These scenarios are typical for monitoring and safety related applications where each node needs information about its neighborhood, e.g., in vehicular ad hoc networks. In IEEE 802.11 based ad hoc networks, one reason not to receive a packet is due to collisions caused by the well known hidden terminal problem (stressed in the addressed scenario where RTS/CTS mechanism is not applicable). It is also well known that wireless communication protocols may achieve different performance results when assuming different radio propagation models and implementations [1]. While the effect of the hidden terminal problem is well understood when utilizing a deterministic1 radio propagation model, it has a new ‘flavor’ with the utilization of more realistic2 ones, which do not experience a fixed Carrier Sense range (CS). Our contribution in this document is a formalization of a metric able to characterize the effect of different propagation models on IEEE 802.11 networks, and its evaluation (using the ns-2.28 simulator) with respect to packet reception rates. The new metric, which we name Packet Level Incoordination (PLI), is based on the CSMA/CA principle and measures the inability of CSMA/CA of correctly coordinate the nodes on a network from a specific node’s perspective (see Fig. 1). This new metric can assist researchers to understand the details of wireless communications, and thus, in the process to find the best strategies (e.g., power control) when designing optimal protocols. The reminder of the paper is the following: Section II briefly presents radio propagation principles, and the way they and the physical layer are implemented in the used simulator. In Section III, we provide the general definition of PLI and the simulation results. Section IV concludes the paper.