Impact of CSI on radio resource management techniques for the OFDMA Downlink

Leonidas Sivridis*, Xinheng Wang, Jinho Choi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 subcarrier 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 [1] 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.

Original languageEnglish
Pages (from-to)306-311
Number of pages6
JournalJournal of Communications
Issue number4
Publication statusPublished - 2011
Externally publishedYes


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