Wireless Ad Hoc and Sensor Networks

354 Wireless Ad Hoc and Sensor Networksfair allocation of bandwidth with a 10 to 20% increase in throughput andminimum end-to-end delays and delay variations, resulting in a better QoS.Next, the implementation of an ADFS scheme for WSNs is discussed.The objective is to evaluate the hardware capabilities and implementationviability. The results indicate where hardware constraints must be alleviated,thus providing direction for future hardware redesign that meetsthe requirements of the ADFS protocol. More topologies will be utilizedto evaluate the protocol.In the ADFS protocol, weights are updated, and the updated weightsare used in making the scheduling decisions and also in the calculationof the backoff intervals in the CSMA/CA paradigm. Initial weights areassigned to the flows based on the service they expect from the network.The effectiveness of the proposed ADFS protocol was evaluated throughhardware experimentation. The results show that the proposed protocolcan achieve fair allocation of bandwidth with a 13.3% increase in throughput,lower end-to-end delays, and delay variations reduced by 55% (standard),resulting in a better QoS. This shows the ability of the ADFSscheduler to be effectively applied to WSN systems to enhance networkperformance; however, further study is needed to address the current hardwareconstraints and improve overall performance of the implementation.This chapter also introduced the energy-aware and fair protocol forWSNs by taking into account the application considerations. This protocolenables higher throughput in the sensor network and consumesless energy per bit when compared to the standard 802.11. It was demonstratedthat the scheme allows fully DPC and has rendered betterperformance in the presence of radio channel uncertainties. Introductionof sleep mode has not decreased throughput of the network. Moreover,the protocol with the sleep-mode solution uses significantly less transmitterpower per bit compared to 802.11 or the original DPC implementation;hence, the energy is saved and lifetime of sensors extended.Second, the fair scheduling protocol is incorporated that ensures performancein the presence of unusual events for sensor networks. The performanceof the energy-aware scheme consisting of scheduling, DPCwith sleep mode is demonstrated in the presence of fading channels.Simulation results justify theoretical conclusions.ReferencesBennett, J.C.R. and Zhang, H., WF2Q: worst-case fair weighted fair queueing,Proceedings of the IEEE INFOCOM’96, Vol. 1, March 1996, pp. 120–128.Brogan, W.L., Modern Control Theory, 3rd ed., Prentice Hall, NJ, 1991.Demers, A., Keshav, S., and Shenker, S., Analysis and simulation of a fair queuingalgorithm, Proceedings of the IEEE INFOCOM, 2000.