Cross Layer Scheduling in Wireless Networks

Wireless channel poses significant challenges to resource management due to multipath fading. In this chapter, we review the impact of wireless channel on the design of scheduling algorithms at the link and network layers. It has been well recognized now that significant performance gains can be obtained by designing channel aware scheduling algorithms. Various scheduling schemes catering to different Quality of Service (QoS) objectives such as maximizing throughput, minimizing delay, or minimizing energy have been proposed in the literature. Most of these algorithms can be formulated as control problems within the framework of Constrained Markov Decision Processes. We examine some of the representative work in this area with a specific focus on centralized scheduling in a single cell scenario with single antenna system. Over the past decade, there has been a large scale proliferation of wireless communications technologies. While the first and second generation (1G and 2G) cellular systems were driven primarily by voice based cellular telephony, the recent years have witnessed a phenomenal increase in packet data applications like email, web browsing, peer to peer and multimedia applications. These applications require Quality of Service (QoS) guarantees in terms of rate, delay, packet loss etc. The time varying nature of the wireless channel due to multipath fading poses significant challenges to radio resource management for providing QoS. In this chapter, we focus on packet scheduling aspect of resource management. Recent results suggest that significant performance gains can be obtained by exploiting wireless channel characteristics for the design of scheduling algorithms at the link and network layers. These algorithms are referred to as cross layer scheduling. Cross layer scheduling algorithms can be formulated as optimization problems Nitin Salodkar Department of Computer Science and Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India Abhay Karandikar Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India. This work was supported by TTSL-IIT Bombay Center for Excellence in Telecom.