On the Design and Deployment of Low-cost Wireless Infrastructure

Abstract: In this thesis, we investigate different methods forreducing the infrastructure deployment costs of wirelessnetworks that should transmit very high data rates.Today,wireless local area networks (WLANs) are usuallyconsidered as the typical paradigm for a low-cost,high datarate wireless communication system. WLANs are becomingincreasingly common as a complement to, or a replacementof,wired LANs in offices or private homes.We will study different design approaches and deploymentstrategies for such networks,specially for possible futuresystems, operating at frequencies up to 60 GHz. The goal is toidentify potential bottlenecks and propose suitable solutionsfor increasing the user data rates,while keeping the overallinstallation and operation costs low.We show that simple installation methods, such as theproposed user deployment and grid installation approaches, canconsiderably reduce the infrastructure costs. The former avoidsnetwork planning completely and the access points are set upwherever it is convenient for the user, whereas the latterrequires some basic coverage planning with the help of atopographic map or a foor plan. Both methods can often achievereliable coverage and data rates comparable to carefullyplanned networks. However, sophisticated network planning is insome situations advantageous. Hence, we also study differentoptimization methods with the objective to find simple, yeteffective algorithms for finding the optimal positioning of APssuch that both the coverage area and the network capacity aremaximized.The performance of the proposed deployment methods andoptimization algorithms is evaluated in a number of typicalenvironments, i.e. places where high data rate wirelessservices are likely being used. Estimates for the requiredinfrastructure densities are obtained from system-levelsimulations. The results show that the installation method hasonly a moderate influence on the network capacity, compared toother fundamental system design choices,suc h as multipleaccess schemes or radio resource management.In this thesis, we focus on studying unlicensed parts of theradio spectrum. Unlicensed operation creates significantchallenges for the radio resource management, which should bedistributed,robust, yet very effective. Autonomous channelassignment schemes and power control strategies are thereforestudied and compared for the different deployment methods. Theresults indicate that relatively simple schemes generallysuffice and achieve an acceptable performance. However,sophisticated system designs and advanced RRM schemes cansubstantially enhance the network capacity or, moreimportantly, allow reducing the infrastructure costs if thecapacity is kept constant. Improvements by a factor of 2 seempossible in both cases.