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Title: Improved link adaptation for beyond 3G systems
Author: Tougheed, Hassan
ISNI:       0000 0004 2708 2077
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2011
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Adaptive Modulation and Coding (AMC) is an essential feature in the forward link of beyond 3G cellular networks. AMC requires up to date knowledge of channel conditions at the base station. The latency in AMC loop due to measurement and reporting of channel quality feedback by mobile and the scheduling delay at base station makes this feedback outdated at the time of its usage, especially for significant mobility. This work proposes two novel techniques to mitigate the effect of above-mentioned latency. In the first method, a moving average of channel quality reports is performed at the base station in order to select modulation scheme and coding rate. In the second approach, the terminal reports a linearly predicted channel quality estimate, in a lookahead manner, instead of reporting the most recent estimate. The two schemes are substantiated by simulations performed for an HSDPA (High Speed Downlink Packet Access) FDD (Frequency Division Duplex) system. Both schemes are shown to provide significant improvement in link throughput that is more pronounced for the channel environments where mobile speed is medium to high and/or there is lack of multipath diversity. Finally moderate complexity equalizer structures are discussed for WCDMA (Wideband Code Division Multiple Access) based HSDPA air interface. Simulation results have been used to obtain quantitative measure of combined advantage of proposed AMC improvements and equalization to conclude the benefits of both are complementary.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available