Multiuser diversity with outdated channel feedback

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

5 Scopus citations


Inspired by the information theoretic results concerning multiuser diversity, we address practical issues in implementing multiuser diversity in a realistic multiple access wireless setting. Using the optimal channel-assigning policy that assigns the channel to only one user with the best channel gain [1], our emphasis is on the effects of channel feedback delay in downlink transmissions. A finite set of M-QAM constellations is adopted and a constant transmit power is assumed in this practical scenario. Based on the closed-form expressions for exact and approximate average BER and sum throughput we derive under the outdated channel feedback model, we illustrate the impact of channel feedback delay on the achievable multiuser diversity gain with the number of users. Simple and accurate asymptotic approximations are also provided in the limit of large number of users. A novel robust constant power, variable rate M-QAM scheme that is less sensitive to feedback delay is proposed using the optimal set of switching thresholds, which is derived to maximize the average sum throughput subject to an average BER constraint.

Original languageEnglish (US)
Title of host publication2004 IEEE Wireless Communications and Networking Conference, WCNC 2004
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages6
ISBN (Print)0780383443
StatePublished - Sep 27 2004
Event2004 IEEE Wireless Communications and Networking Conference, WCNC 2004 - Atlanta, GA, United States
Duration: Mar 21 2004Mar 25 2004


Other2004 IEEE Wireless Communications and Networking Conference, WCNC 2004
Country/TerritoryUnited States
CityAtlanta, GA

ASJC Scopus subject areas

  • General Engineering


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