Variable power and rate allocation using simple CQI for multiuser OFDMA-CDM systems

Authors:
Kwang Soon Kim;Yun Hee Kim
Affiliations:
Dept. of Electrical and Electronic Engineering, Yonsei University, Seoul, Korea;Dept. of Electronics and Radio Engineering, Kyung Hee University, Yongin, Korea
Venue:
IEEE Transactions on Wireless Communications
Year:
2009

Citing 5
Cited 0

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Abstract

This paper presents variable power and rate allocation (PRA) for a multiuser orthogonal frequency division multiple access code division multiplexing (OFDMA-CDM) system which exploits both orthogonality among users and symbol-level diversity. To predict the link performance, we analyze the post-processing SNR as the transmit power (TP) varies when the minimum mean square error combiner (MMSEC) is employed. It is shown from analysis that the MMSEC SNR is nonlinear in TP, but is bounded by the harmonic and the arithmetic means of the subcarrier SNRs. From the observation, we propose two variable PRA methods using a simple channel quality indication and a required TP estimation method. Simulation results show that the proposed methods not only guarantee the target performance but also increase the throughput at the same or slightly increased feedback overhead compared with the fixed TP allocation case.