Improved Subcarrier Allocation in Multi-User OFDM Systems

Won Joon LEE  Jaeyoon LEE  Dongweon YOON  Sang Kyu PARK  

IEICE TRANSACTIONS on Communications   Vol.E91-B    No.12    pp.4030-4033
Publication Date: 2008/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.12.4030
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
OFDM,  subcarrier allocation,  outage probability,  spectral efficiency,  

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In a multi-user orthogonal frequency division multiplexing (OFDM) system, efficient resource allocation is required to provide service to more users. In this letter, we propose an improved subcarrier allocation algorithm that can increase the spectral efficiency and the number of total transmission bits even if the number of users is too large. The proposed algorithm is divided into two stages. In the first stage, a group of users who are eligible for services is determined by using the bit error rate (BER), the users' minimum data rate requirement, and channel information. In the second stage, subcarriers are first allocated to the users on the basis of channel state, and then the reallocation is performed so that resource waste is minimized. We show that the proposed algorithm outperforms the conventional one on the basis of outage probability, spectral efficiency, and the number of total transmission bits through a computer simulation.