Research Article
Optimal Subcarrier Sharing for Weighted Sum of Rates Maximization in Multiuser-OFDM Systems
@INPROCEEDINGS{10.1109/WIOPT.2007.4480090, author={Ayman Alsawah and Inbar Fijalkow}, title={Optimal Subcarrier Sharing for Weighted Sum of Rates Maximization in Multiuser-OFDM Systems}, proceedings={3rd International ICST Workshop on Resource Allocation in Wireless Networks}, publisher={IEEE}, proceedings_a={RAWNET}, year={2008}, month={3}, keywords={Bit error rate Dispersion Diversity methods Downlink Interference constraints Laboratories Local area networks OFDM modulation Quality of service WiMAX}, doi={10.1109/WIOPT.2007.4480090} }- Ayman Alsawah
Inbar Fijalkow
Year: 2008
Optimal Subcarrier Sharing for Weighted Sum of Rates Maximization in Multiuser-OFDM Systems
RAWNET
IEEE
DOI: 10.1109/WIOPT.2007.4480090
Abstract
We consider the maximization of the weighted sum of rates in a multiuser OFDM system with dynamic subcarrier allocation and subcarrier-wise adaptive modulation and power. We assume a total peak power constraint and a target bit error rate (BER). We allow each subcarrier to be shared by more than one user. This sharing implies an interference which the receivers deal with as noise. In this paper, we show that the resulting non-convex optimization problem can be decomposed into two tractable subproblems: a subcarrier assignment and a power allocation. We prove that the optimal subcarrier assignment is exclusive, i.e. each subcarrier has to be allocated to one user only. The optimal power allocation corresponds to a multilevel water-filling. Since the solutions to these two subproblems are mutually dependent, one can use exhaustive search to explicit the optimal subcarrier assignment. To avoid the burden of exhaustive search, we show that a close-to-optimal low-complexity solution is obtained if the total power is equally partitioned among the subcarriers. Finally, simulation results show that the proposed suboptimal solution yields a significant gain in terms of average weighted sum of rates compared to a traditional static subcarrier allocation.
