Cross-Layer Design for QoS Support in Multihop Wireless Networks

Due to such features as low cost, ease of deployment, increased coverage, and enhanced capacity, multihop wireless networks such as ad hoc networks, mesh networks, and sensor networks that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. Providing efficient quality of service (QoS) support is essential for such networks, as they need to deliver real-time services like video, audio, and voice over IP besides the traditional data service. Various solutions have been proposed to provide soft QoS over multihop wireless networks from different layers in the network protocol stack. However, the layered concept was primarily created for wired networks, and multihop wireless networks oppose strict layered design because of their dynamic nature, infrastructureless architecture, and time-varying unstable links and topology. The concept of cross-layer design is based on architecture where different layers can exchange information in order to improve the overall network performance. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. This paper aims to review the present study on the cross-layer paradigm for QoS support in multihop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. Realizing the new trends for wireless networking, such as cooperative communication and networking, opportunistic transmission, real system performance evaluation, etc., several open issues related to cross-layer design for QoS support over multihop wireless networks are also discussed in the paper.