Département Réseau, Sécurité et Multimédia Rapport d'Activités 2008

Radio Resource Management in WirelessNetworksWiMAX Radio Resources Management and Capacity EstimationResearch Staff : Xavier Lagrange, Patrick Maillé, Loutfi Nuaymi – Ph.D. Student: Aymen BelghithKeywords : WiMAX, scheduling, QoS, capacity estimation, resource management, pricingApplications : Wireless Internet AccessPartners & Funding : Region BretagneIntroductionWiMAX (Worldwide Interoperability forMicrowave Access) Broadband Wireless AccessTechnology is based on 802.16-2004 standardand its amendment 802.16e [1].This standard defines the physical (PHY) andmedium access control (MAC) layer for fixedand mobile broadband wireless accesssystems. Devices set up a so-called serviceflow to transfer data. A service flow is a MACtransport service that provides unidirectionaltransport of packets with a given quality ofservice either on uplink (packets transmittedby the SS, Subscriber Station) or on downlink(packets transmitted by the BS, Base Station).The dynamic service management is used toadd a new service flow, change the QoSparameters of an existing flow service anddelete an existing service flow.WiMAX radio resource system is very open andmany algorithms are important for capacity:admission control, scheduling, power control,pricing, etc. In this work, we intend to studysome parts of WiMAX radio resourcemanagement and then propose estimations ofWiMAX capacity for some scenarios andenvironments. This work is made in theframework of a PhD study with partial fundingof Région Bretagne.includes many tools. Classical schedulingalgorithms such as Round Robin, Max SIR(Signal-to-Interference Ratio) can be adaptedor associated with other algorithms forWIMAX. Another trend is to define schedulingalgorithms specifically for WiMAX.An important software development effortallowed the integration of various MACfunctionalities in an existing NS-2 (NetworkSimulator) WiMAX module [2]. We introducedseveral WiMAX QoS features and theimplementation of some schedulers and theevaluation of some parameters. Our modifiedWiMAX NS-2 module is described in detail in[3]. New interesting simulation results aboutWiMAX scheduling were obtained and will bepublished in [4]. The spectrum efficiency andmean sojourn time performance measures aredetermined through simulations. Spectrumefficiency is plotted for different schedulers(see Fig.1). We verify that scheduling based onthe maximum SIR (mSiR)) scheduler providesthe highest spectrum efficiency and the worstdelay to deliver data frames, independently ofthe quality of the channel.RealizationFirst, a study of dynamic service managementhas been realized. The power control in theWirelessMAN-OFDM PHY layer has beenstudied. The power control has two stages: theinitial calibration and the periodic adjustmentprocedure. Then, a review of WiMAXscheduling techniques has been made. TheWiMAX scheduling environment as defined inthe IEEE 802.16 standard is very open andFuture WorkFig.1: Spectrum efficiencyOther WiMAX scheduling studies are currentlyfinalized and will be submitted to two Researchconferences.Pracom’s Annual Report 2008 17