Performance Improvement of Proportional Fairness-Based Resource Allocation in OFDMA Downlink Systems

Nararat RUANGCHAIJATUPON  Yusheng JI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A   No.9   pp.2191-2199
Publication Date: 2009/09/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.2191
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Multi-dimensional Mobile Information Networks)
Category: Broadband Wireless Access System
Keyword: 
OFDMA,  cross-layer scheduling,  proportional fairness,  multiuser diversity,  multichannel,  IEEE 802.16,  WiMAX,  

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Summary: 
We have developed a novel downlink packet scheduling scheme for a multiuser OFDMA system in which a subchannel can be time-multiplexed among multiple users. This scheme which is called Matrixed-based Proportional Fairness can provide a high system throughput while ensuring fairness. The scheme is based on a Proportional Fairness (PF) utility function and can be applied to any of the PF-based schedulers. Our scheduler explores multichannel multiuser diversity by using a two-dimensional matrix combining user selection, subchannel assignment, and time slot allocation. Furthermore, unlike other PF-based schemes, our scheme considers finitely backlogged queues during the time slot allocation. By doing so, it can exploit multichannel multiuser diversity to utilize bandwidth efficiently and with throughput fairness. Additionally, fairness in the time domain is enhanced by limiting the number of allocated time slots. Intensive simulations considering finitely backlogged queues and user mobility prove the scheme's effectiveness.