Open Access

Throughput Maximization under Rate Requirements for the OFDMA Downlink Channel with Limited Feedback

  • Gerhard Wunder1Email author,
  • Chan Zhou1,
  • Hajo-Erich Bakker2 and
  • Stephen Kaminski2
EURASIP Journal on Wireless Communications and Networking20072008:437921

DOI: 10.1155/2008/437921

Received: 1 May 2007

Accepted: 26 August 2007

Published: 5 September 2007

Abstract

The purpose of this paper is to show the potential of UMTS long-term evolution using OFDM modulation by adopting a combined perspective on feedback channel design and resource allocation for OFDMA multiuser downlink channel. First, we provide an efficient feedback scheme that we call mobility-dependent successive refinement that enormously reduces the necessary feedback capacity demand. The main idea is not to report the complete frequency response all at once but in subsequent parts. Subsequent parts will be further refined in this process. After a predefined number of time slots, outdated parts are updated depending on the reported mobility class of the users. It is shown that this scheme requires very low feedback capacity and works even within the strict feedback capacity requirements of standard HSDPA. Then, by using this feedback scheme, we present a scheduling strategy which solves a weighted sum rate maximization problem for given rate requirements. This is a discrete optimization problem with nondifferentiable nonconvex objective due to the discrete properties of practical systems. In order to efficiently solve this problem, we present an algorithm which is motivated by a weight matching strategy stemming from a Lagrangian approach. We evaluate this algorithm and show that it outperforms a standard algorithm which is based on the well-known Hungarian algorithm both in achieved throughput, delay, and computational complexity.

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Authors’ Affiliations

(1)
Fraunhofer German-Sino Lab for Mobile Communications, Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut
(2)
Alcatel-Lucent Research & Innovation

Copyright

© Gerhard Wunder et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.