Subcarrier allocation in OFDMA systems: beyond water-filling

• Published in: 2004 38th Asilomar Conference on Signals, Systems and Computers Vol. 1; pp. 334 - 338 Vol.1
• Main Authors: Kittipiyakul, S., Javidi, T.
• Format: Conference Proceeding
• Language: English
• Published: Piscataway NJ IEEE 2004
• Subjects: Applied sciences; Computational modeling; Counting circuits; Delay; Detection, estimation, filtering, equalization, prediction; Diversity methods; Exact sciences and technology; Fading; Information, signal and communications theory; Multiplexing; Numerical simulation; OFDM; Organization, operation and development plans; Radiocommunications; Real time systems; Signal and communications theory; Signal, noise; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Throughput; Time varying systems; Transmission and modulation (techniques and equipments); Performance evaluation; Parameter estimation; Frequency division multiple access; Frequency allocation; Information rate; Teletraffic; Subcarrier; Algorithm; Information transmission; Time variation; Implementation; Arrival time; Idling; Queueing system; Optimal allocation; Channel estimation; Traffic management; Orthogonal frequency division multiplexing; Traffic control; Numerical simulation; Delay time; Comparative study
• ISBN: 0780386221; 9780780386228
• DOI: 10.1109/ACSSC.2004.1399148

This paper considers the issue of optimal subcarrier allocation in OFDMA. When including time-varying packet arrivals and channels, we show, via a counter example, that water-filling-based subcarrier allocation policies, contrary to conventional wisdom, fail to provide rate-stability for an otherwise stabilizable OFDMA system. We briefly discuss the long-run throughput optimality in OFDM as demonstrated in (S. Kittipiyakul et al., 2004). In particular under a simple channel model, we consider a nonidling policy which balances the queues and outperforms water-filling policies by achieving the minimum average delay. In this paper, we provide simple computation algorithms for implementing such policies and provide simulations for a numerical comparative study.