QoS-aware routing based on capacity estimation for mobile ad hoc networks

Mobile ad hoc networks (MANETs) are rapidly evolving and the notion of ad hoc networking has become one of the most challenging research areas of wireless communications. The rising popularity of real-time applications among end users in MANETs has stimulated a surge of research in routing and providing quality of service (QoS) support in such networks. Capacity estimation is a key component of any admission control scheme required to support QoS provision in MANETs. A number of schemes have been previously proposed to estimate residual capacity that is derived from window-based measurements of channel estimation. In this paper, a new capacity-constrained QoS-aware routing scheme is proposed. The novel part of this scheme is a simple additional mechanism to estimate residual capacity in IEEE 802.11-based ad hoc networks. The scheme proposes the use of a `forgiveness factor' to weight these previous measurements and, it is shown through simulation-based evaluation to provide improved utilizations estimation and better available capacity based admission control.

I. Introduction

Bandwidth or more strictly speaking capacity estimation is a fundamental component in the provision of quality-of-service (QoS) in mobile ad hoc networks (MANETs). However, accurate capacity estimation can be difficult; because each host has only imprecise knowledge of the network status; thus an effective estimation scheme is highly desirable. Many previously proposed schemes [1]–[4] adopt ’Listen’-based estimation techniques derived from IEEE 802.11 MAC/PHY specification. The ’Listen’ scheme requires each node to listen to the channel and estimate the local residual capacity based on the measurement of the local channel utilization. Given the local channel utilization and the maximum achievable channel capacity , the local residual capacity is estimated using the following equation: $$C_{res}=(1-u(t)).C_{{\max}} \eqno\hbox{(1)}$$