Performance of limited feedback schemes for downlink OFDMA with finite coherence time

Jieying Chen*, Randall A Berry, Michael L Honig

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

23 Scopus citations

Abstract

We consider the capacity or a downlink Orthogonal Frequency Division Multiple Access (OFDMA) system with limited feedback rate RF per sub-channel and finite coherence time T. The feedback is used to relay channel stale information (CSI) from K users to the base station. The order-optimal capacity growth with Rayleigh fading sub-channeLs is Θ(N log log K) as N and K increase with fixed ratio, where N is the number of sub-channels. However, to achieve this, previous work requires a feedback rate per subchannel that scales linearly with the system size. Here we explicitly include the feedback overhead when calculating the sum capacity, and study the tradeoff between feedback rate and sum capacity. We propose two limited feedback schemes, one based on sequential transmissions across users and the other based on random access, in which the each feedback bit requests the use of a sub-channel group containing multiple sub-channels. With fixed RFT, the sum capacity for both schemes with optimized sub-channel groups increases as Θ(N.). If RFT grows faster than log K, then both schemes can achieve the order-optimal capacity growth. We also show that when RFT is small, the random access scheme performs better than the sequential transmission scheme, whereas the reverse is true for large RFT.

Original languageEnglish (US)
Title of host publicationProceedings - 2007 IEEE International Symposium on Information Theory, ISIT 2007
Pages2751-2755
Number of pages5
DOIs
StatePublished - Dec 1 2007
Event2007 IEEE International Symposium on Information Theory, ISIT 2007 - Nice, France
Duration: Jun 24 2007Jun 29 2007

Other

Other2007 IEEE International Symposium on Information Theory, ISIT 2007
CountryFrance
CityNice
Period6/24/076/29/07

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Information Systems
  • Modeling and Simulation
  • Applied Mathematics

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