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An investigation of dynamic subcarrier allocation in MIMO–OFDMA systems

Research output: Research - peer-reviewArticle

Original languageEnglish
Pages (from-to)2990 - 3005
Number of pages16
JournalIEEE Transactions on Vehicular Technology
Issue number5, part 2
StatePublished - Sep 2007


In this paper, orthogonal frequency-division multiple-access (OFDMA) systems with dynamic deterministic (as opposed to pseudorandom) allocation of subcarriers to users to exploit multiuser diversity are investigated. Previously published work on dynamic multiuser subcarrrier allocation for OFDMA systems with single-input-single-output (SISO) channels are surveyed. A near-optimal low-complexity algorithm for SISO systems, which is structurally similar to the algorithm by Rhee and Cioffi, is extended to the case of multiple-input-multiple-output (MIMO) systems in this paper. The optimality and adaptability of this algorithm are analyzed by formulating an assignment problem and comparing with one optimal and two extended suboptimal strategies proposed based on previous work. Consideration of a MIMO channel creates further issues for the subcarrier-allocation process. In particular, methods whereby an appropriate subcarrier allocation may be exploited to minimize the effects of correlation in MIMO channels are of considerable interest. Several novel variants of the algorithm (referred to as ldquoschemesrdquo) are proposed and evaluated for MIMO systems employing both space-time block coding (STBC) and spatial multiplexing (SM) in both uncorrelated and correlated fading channels. Simulation results identify the most suitable schemes for both STBC and SM and, in particular, show that substantial improvements in performance (in terms of bit-error rate) in correlated channels can be achieved by means of suitable subcarrier allocation. In uncorrelated channels, the best scheme can offer approximately 7-dB gain over the conventional MIMO channel; in highly correlated channels, even more substantial improvements (>11-dB gain for STBC, >20-dB gain for SM) in performance can also be achieved, demonstrating the ability of a well-designed subcarrier-allocation scheme to mitigate the debilitating effects of correlation on MIMO systems

Additional information

Publisher: Institute of Electrical and Electronics Engineers (IEEE) Rose publication type: Journal article Sponsorship: This work was supported by Kyocera R&D Terms of use: Copyright © 2007 IEEE. Reprinted from IEEE Transactions on Vehicular Technology. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Bristol's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

    Research areas

  • single input single output (SISO), space-time block coding (STBC), subcarrier allocation, multiple input multiple output (MIMO), orthogonal frequency-division multiple access (OFDMA), spatial multiplexing (SM)

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