EURASIP Journal on Wireless Communications and Networking
Volume 2009 (2009), Article ID 298451, 9 pages
doi:10.1155/2009/298451
Research Article

Dynamic Subcarrier Allocation for Real-Time Traffic over Multiuser OFDM Systems

Fanglei Sun,1 Mingli You,1 and Victor O. K. Li2

1Research and Innovation Center, Alcatel-Lucent Shanghai Bell Co., Ltd, Shanghai 201206, China
2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong

Received 24 January 2009; Accepted 14 April 2009

Academic Editor: Dmitri Moltchanov

Copyright © 2009 Fanglei Sun et al. 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.

Abstract

A dynamic resource allocation algorithm to satisfy the packet delay requirements for real-time services, while maximizing the system capacity in multiuser orthogonal frequency division multiplexing (OFDM) systems is introduced. Our proposed cross-layer algorithm, called Dynamic Subcarrier Allocation algorithm for Real-time Traffic (DSA-RT), consists of two interactive components. In the medium access control (MAC) layer, the users' expected transmission rates in terms of the number of subcarriers per symbol and their corresponding transmission priorities are evaluated. With the above MAC-layer information and the detected subcarriers' channel gains, in the physical (PHY) layer, a modified Kuhn-Munkres algorithm is developed to minimize the system power for a certain subcarrier allocation, then a PHY-layer resource allocation scheme is proposed to optimally allocate the subcarriers under the system signal-to-noise ratio (SNR) and power constraints. In a system where the number of mobile users changes dynamically, our developed MAC-layer access control and removal schemes can guarantee the quality of service (QoS) of the existing users in the system and fully utilize the bandwidth resource. The numerical results show that DSA-RT significantly improves the system performance in terms of the bandwidth efficiency and delay performance for real-time services.