Tone diversity for OFDMA in broadband wireless communications
This paper presents two group-based tone diversity schemes, namely, group-orthogonal tone-combining-diversity (GO-TCD) and group-optimal tone-selection-diversity (GO-TSD), for orthogonal frequency division multiple access (OFDMA) system in broadband wireless communications. In both schemes, the entire frequency band of N sub-carriers is divided into N-G = N/L-f sub-carrier groups with each having L-f sub-carriers. When the channel knowledge is not available at the transmitter, GO-TCD, which has a split-and-group structure to reduce the peak-toaverage ratio (PAR) and employs the multi-user detection for maximum-likelihood (ML) estimation to increase the number of active users, is proposed and shown to provide a lower PAR and similar performance as compared with the group-orthogonal multi-carrier CDMA, and outperforms the random-hopping (RH)-OFDMA and matched-filter based MC-CDMA. When the channel knowledge is available at the transmitter, GO-TSD can be used to select the best sub-carrier in a given sub-carrier group for any active user and shown to offer a throughput comparable to the optimal tone selection but with much less complexity. Copyright (c) 2006 John Wiley & Sons, Ltd.
tone diversity ofdma group-orthogonal multiple-access reduced par