7138

6648

كارشناسي ارشد

مخابرات

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق وكامپيوتر

1390

يازده، 85ص: جدول، نمودار

ص.ع. به فارسي وانگليسي

جمال الدين گلستاني

3/8/91

1396/09/20

كتابنامه

برق وكامپيوتر

مهندسي برق و كامپيوتر

ID6648

به فارسي وانگليسي:قابل رويت درنسخه ديجيتالي

Exploiting Multi User Diversity in Wireless Systems in the Presence of Fairness Constraint Babak Siabi b siabi@ec iut ac ir Date of Submission October 15 2011 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Jamaloddin Golestani golestani@sharif eduAbstract Increasing users tendency to high data rate applications motivated researchers in various fields ofcommunications to intensively look for inherent abilities of the communication systems which are useful toincrease the system efficiency Multi user diversity is the interesting and unique characteristic of the multi user wireless systems such as cellular networks In such systems at the same time that some usersexperience deep fading there may be some other users whose channel condition is good As a consequence at any time in a large network a network with many users with high probability there is a user whosechannel is near its peak By utilizing this concept the total throughput of a multi user system is increasable There is a simple channel assignment policy that fully exploits the existing multi user diversity At eachtime the policy assigns the channel to the user who has the best channel condition at that time This policyis called opportunistic channel assignment Opportunistic channel assignment is unfair in the sense that the user with a poor channel condition haslittle chance to be served even in a long time interval Since fairness is an important requirement of manymulti user scenarios it is desirable to find channel assignment policies which make proper compromisebetween utilizing multi user diversity and fairness Adding fairness constraint to multi user diversityutilization makes the channel assignment problem complicated In this thesis we study the channel assignment problem in multi channel wireless systems We try tofind solutions to the channel assignment problem with the objective of utilizing multi user diversity underfairness constraint Toward this goal different definitions of fairness are considered and under eachdefinition channel assignment problem is expressed as an optimization problem We propose two channelassignment policies for multi channel wireless systems and prove the optimality of them Each policycorresponds to a specific fairness definition and by optimality of a policy we mean the highest throughputamong all policies which provide corresponding fairness We adapt our policies to practical applications anddemonstrate their efficiencies through simulations Moreover we investigate the trade off between utilizingmulti user diversity and fairness through some appropriate simulation results Key Words Wireless Communications Systems Multi User Diversity ChannelAssignment Fairness

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