Journal of Communications, Vol 6, No 4 (2011), 306-311, Jul 2011
doi:10.4304/jcm.6.4.306-311

Impact of CSI on Radio Resource Management Techniques for the OFDMA downlink

Leonidas Sivridis, Xinheng Wang, Jinho Choi

Abstract


Adaptive resource allocation can drastically increase the throughput of an Orthogonal Frequency Division Multiple Access (OFDMA) system when the Channel State Information (CSI) is accurately known. Unfortunately, in practice, perfect  CSI is rarely possible. In this paper, we consider adaptive sub-carrier assignment for downlink multiuser OFDMA systems, where the transmitter has no knowledge of the instantaneous channel realizations. The problem we address is  maximizing the sum-capacity of the system subject to user  Quality of Service (QoS) requirements.  A heuristic algorithm presented in \cite{Zhang06} is modified in order to provide an enhanced sub-optimal solution.  Numerical results show that resources can be adaptively allocated using statistical CSI (SCSI) and that such an approach allows for an important number of user QoS requirements to be met. Comparisons between the instantaneous CSI (ICSI) and SCSI based resource allocation schemes demonstrate that their performance difference is highly dependent on the number of active users present in the cell, the QoS constraint,
and the transmit power.


Keywords


OFDMA;Radio Resource Management;CSI; statistical CSI.

References


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