Exploiting multiuser diversity with contention-based opportunistic feedback in wireless communication systems

Hang Li

    Research output: ThesisDoctoral Thesis

    111 Downloads (Pure)

    Abstract

    For multi-user wireless communications, information theory has demonstrated that system performance can be significantly improved by exploiting multi-user diversity, where the channel is always scheduled to the user with the best instantaneous channel gain. For achieving the benefit of multi-user diversity, conventionally, all users' channel state information (CSI) must be available at the Base Station (BS), thereby inducing enormous system overhead. In a wireless communication system with a large number of users, the overhead induced by polling CSIs may overshadow the multiuser diversity gain. The first part of this dissertation (Chapters 2 and 3) proposes a user identification approach (UIDA) to handle the overhead issue in a generic wireless network exploiting multiuser diversity, and demonstrates two user identification (UID) design methods and application in the orthogonal frequency-division multiplexing (OFDM) system and the multiple-input multiple-output OFDM (MIMO-OFDM) system. Then, we present a theoretical upper bound of the throughput of the system with the UIDA over general channels. In addition, a modified UIDA is proposed to effectively trade off throughput and fairness performances. In comparison with Medium Access Diversity and Multiuser Diversity with Capture (two alternative approaches in the literature for exploiting multiuser diversity), the proposed UIDA achieves better throughput performance when there are a reasonably large number of users. Following the above work, a simplified UIDA for multiuser diversity with enhanced throughput is proposed in Chapter 3 to reduce the overhead further by allowing a small degree of outage to occur.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2013

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