The performance of random CSMA networks with threshold scheduling
Abstract: Wireless ad-hoc networks (WANET) are networks with no pre-existing infrastructure, where each user can reach its destination directly, or through other users (multiple hops transmission). This type of networks, have attracted growing interest in recent years, an interest which comes from their ability to provide instant wireless networking solutions in situations where infrastructure is missing or is expensive to establish (such as military battle fields, emergency operations, sensor networks), offering simplicity, scalability and flexibility.
The performance of wireless ad-hoc networks (WANETs) is typically limited by the mutual interference between its nodes. Two of the important approaches to reduce the mutual interference are medium access control protocols and smart power allocation schemes.
In this work, we consider the utilization of a threshold scheduling scheme in a slotted CSMA WANETs, and investigate its influence on the network performance. The work is motivated by the fact that both mechanisms can cause a node to back-off. Threshold scheduling causes backoff due to channel conditions, while CSMA causes back-off due to interference conditions. Our focus is on the analysis of the behavior of such network under the constraint of a total backoff probability. In particular we study the optimal division of this probability between the two mechanisms.
In our work, we present a closed form analytic expression for the optimal division of the back-off probability between the threshold scheduling scheme and the CSMA in the low back-off regime. This expression presents the trade-off between the CSMA mechanism and the threshold scheduling scheme and enables the evaluation of the optimal performance. It enables us to examine the system performance as a function of some of the system parameters, such as the channel decay factor and the system rate value.
* M.Sc. thesis directed by Dr. Itsik Bergel