Scheduling for Energy Conservation and Quality Enhancement in Multi-hop Wireless Networks

Download or read book Scheduling for Energy Conservation and Quality Enhancement in Multi-hop Wireless Networks written by Ashima Gupta and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks and devices are ubiquitous today. This is primarily due to the increased mobility, flexibility and connectivity as well as high speed and low cost deployment that they provide. However quality of service, capacity, spectral efficiency and battery lifetime are some major concerns of wireless devices and networks. The broadcast nature of wireless media makes them prone to losses and high bit error rates. These variabilities make it challenging to guarantee quality of service parameters like rate, latency and jitter. Wireless devices consume more power than corresponding wired devices. These devices function on limited battery capacity to facilitate portability and mobility. Hence, their operational lifecycle is governed by the efficiency of their battery usage. The objective of this thesis is to analyze and apply novel application aware cross-layer scheduling techniques for energy conservation and quality enhancement in multi-hop wireless networks. We focus on scheduling techniques as many of these can integrated with existing systems and incorporated in new designs. Application awareness helps to identify the constraints and requirements at lower network layers (network and MAC layer). This facilitates the lower layers to perform prioritized scheduling to optimize bandwidth utilization for class differentiated flows and devise adaptive sleep-awake scheduling while minimizing the impact on quality of service. Specifically, we identify three applications: OFDMA based multi-hop networks, Sensor networks and Voice over Internet Protocol (VoIP). We model QoS aware centralized slot allocation scheme for prioritized flows in OFDMA based networks as an ILP that maximizes the described Flow Admittance metric. Several computationally tractable heuristics are compared for efficiency using different topologies and workloads. We enhance this solution for IEEE 802.16j networks making it scalable and adaptive to rate changes and link demands. We illustrate how a multi-channel sensor network scheduling scheme results in considerable energy savings when used to model a moving phenomenon or to deploy a heterogeneous sensor network. This is achieved without significant degradation in data gathering: quality or latency. Finally, we show how an adaptive scanning technique utilizing the sleep-awake scheduling in Wi-Fi networks is used to conserve energy and increase battery lifetime in VoIP Wi-Fi devices.