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A low complexity algorithm for dynamic fair resource allocation in OFDMA systems

by Cavalcanti Moreira, André Luis

Abstract (Summary)
The popularization of the Internet and the demand for high-speed access has ledthe development of Broadband Wireless Access. Despite its great potential, the wirelesscommunications impose some challenges. A main limitation is the transmission mediumitself because the inherently effects of radio propagation such as path loss, frequencyselective fading, Doppler spread and multipath delay-spread.In this context, OFDM is a promising technology because of its tolerance to lossand multipath problems. Due to the combination of independent channels, it is possible touse different modulation in each sub-carrier, according to the channel conditions, atechnique referred to as adaptive modulation and coding. Also, in a point-to-multipointarchitecture, multiple users can share the spectrum by dynamically assigning differentsets of sub-carriers to different users, taking advantage from an effect referred to as multiuserdiversity. In comparison to other multiple-access techniques, OFDMA allows anincreased exploration of multiuser diversity and scheduling with the possibility of finegrained allocation. A great deal of research has looked into adaptive techniques capableof improving network spectral efficiency in multi-user systems. They are usuallyformulated as a constraint optimization problem and know to be NP-hard complex.In this work, we adopt a heuristic approach to deal with this kind of problem. Themain objective is to design an allocation strategy that makes efficient use of availableresources and maximizes overall spectral efficiency. However, an allocation strategy thattargets only the higher spectral efficiency can generate a problem regarding the justice ofthe resource sharing strategy being used. Also, as the wireless systems networks arespreading, it is expected that they can support a wide variety of different services withdifferent requirements of QoS and bandwidth. Hence, we propose an algorithm that letthe network operator balance these requirements. By taking into account the QoSrequirement of the users or applications, the algorithm must give the maximumthroughput possible under these restrictions, established by the network operator or thesystem policies
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Djamel Fawzi Hadj Sadok

School:Universidade Federal de Pernambuco

School Location:Brazil

Source Type:Master's Thesis

Keywords:OFDMA systems Fair resource allocation QoS awareness Sistemas

ISBN:

Date of Publication:08/29/2008

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