5.1 INTRODUCTION

A mobile ad hoc network (MANET) consists of a number of mobile devices that form a network on demand without support from any existing network infrastructure or central administration. In a MANET, mobile devices are connected by wireless links, and every device acts as a router, forwarding data packets for other nodes. Its characteristics include dynamic topology, scarce energy, limited bandwidth, and time-varying link rate [1]. In the past, MANETs have mainly been used in battlefields and disaster areas, where a centralized infrastructure is expensive or even impossible. Nowadays, they are becoming an essential part of the ubiquitous computing environment, but there are several challenges, particularly with respect to improving performance and providing application quality of services (QoS).

Cross-layer design has recently emerged as an important design methodology to cope with the performance issues in the wireless computing environment. To make the concept of cross-layer design clearer, let us review layered network architectures first. One of them is the hybrid reference model, which is used in the Internet [2]. The hybrid reference model is divided into five layers according to the overall networking tasks. Each layer provides certain services to the upper layer while hiding the upper layer from the detailed implementation. Direct communication between nonadjacent layers in the architecture is not allowed and communication between adjacent layers is provided ...

Get Mobile Intelligence now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.