Opportunistic Random Access Scheme Design for OFDMA-based Indoor PLC Networks
Résumé
Multi-user systems can benefit from multi-user diversity by assigning channels to users with best
channel conditions at different time instants. In this paper, we present an opportunistic random access
scheme for OFDMA-based indoor PLC systems, based on time- and frequency-varying channel conditions,
to exploit multi-user diversity. The proposed scheme dynamically adjusts the backoff time of
each user according to its own channel state variations in both time and frequency domains during
the contention procedure, and thus ’better’ users have higher priority to contend over their favorable
subchannels. Moreover, subchannels are assigned to users with best channel conditions in order to
further enhance the system throughput. In addition, an analytical throughput model for such a multiuser
and multi-channel system is derived to obtain the optimal parameter settings of the proposed
access scheme. Simulation results show that the proposed scheme provides significant improvement in
the system throughput even in the case where the number of users highly exceeds that of subchannels.
Origine : Accord explicite pour ce dépôt
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