Design and Performance Evaluation of a Fuzzy-Based Traffic Conditioner for Mobile Ad Hoc Networks

A mobile ad hoc network is a collection of mobile hosts forming a temporary network on the fly, without using any fixed infrastructure. Characteristics of mobile ad hoc networks such as lack of central coordination, mobility of hosts, dynamically varying network topology, and limited availability of resources make QoS provisioning very challenging in such networks. In this paper, we introduce a fuzzy QoS traffic conditioner for mobile ad hoc networks. The proposed traffic conditioner consists of fuzzy admission control (FAC), fuzzy traffic rate controller (FTRC), and fuzzy scheduler (FS). The proposed FAC monitors the delay and available bandwidth and decides whether to accept or reject the request. The FTRC uses the additive increase multiplicative decrease (AIMD) rate control algorithm as a base, in which a node increments its transmission rate when the observed delay is below the predefined threshold, with an increment rate of c Kbps and decreases its transmission rate by r% when the delay passes the threshold. FTRC accepts the packet delay and the "delay-threshold d" as inputs and calculates c and r by using a set of fuzzy rules. The third part of the proposed traffic conditioner is FS, which is based on the traditional weighted round robin (WRR) mechanism. FS monitors the packet drop and delay of each queue and adjusts the queue weights by using a fuzzy inference engine.