Joint Evaluation of Reduced Feedback Scheme, Scheduling, and Rate Adaptation in OFDMA Systems with Feedback Delays

Guharoy, Subhojit and Mehta, Neelesh B (2012) Joint Evaluation of Reduced Feedback Scheme, Scheduling, and Rate Adaptation in OFDMA Systems with Feedback Delays. In: IEEE Global Telecommunications Conference (Globecom), DEC 03-07, 2012 , Anaheim, California, USA, pp. 4566-4571.

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Abstract

Orthogonal frequency division multiple access (OFDMA) systems exploit multiuser diversity and frequency-selectivity to achieve high spectral efficiencies. However, they require considerable feedback for scheduling and rate adaptation, and are sensitive to feedback delays. We develop a comprehensive analysis of the OFDMA system throughput as a function of the feedback scheme, frequency-domain scheduler, and discrete rate adaptation rule in the presence of feedback delays. We analyze the popular best-n and threshold-based feedback schemes. We show that for both the greedy and round-robin schedulers, the throughput degradation, given a feedback delay, depends primarily on the fraction of feedback reduced by the feedback scheme and not the feedback scheme itself. Even small feedback delays at low vehicular speeds are shown to significantly degrade the throughput. We also show that optimizing the link adaptation thresholds as a function of the feedback delay can effectively counteract the detrimental effect of delays.

Item Type:	Conference Proceedings
Publisher:	IEEE
Additional Information:	IEEE Global Communications Conference (GLOBECOM), Anaheim, CA, DEC 03-07, 2012
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	12 Dec 2013 10:10
Last Modified:	12 Dec 2013 10:10
URI:	http://eprints.iisc.ac.in/id/eprint/47861

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