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| A capacity-maximization-based adaptive modulation and power allocation algorighm fo multicarrier systems |
| Zhao Yahong; Zhang Zhongpei; Wu Weiling |
| ①School of Info. Eng., Beijing Univ. of Posts and Telecommunications Beijing 100876 China;②State Key Lab on Microwave & Digital Comm., Tsinghua University Beijing 100084 China |
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Abstract In this paper, the optimization of channel capacity (equivalent to data throughput) is proposed for variable-rate service, which is solved with the Lagrangian multiplier method based on a simplified BER formula for m-QAM modulation. The closed-form solution for the optimization problem is given and the practical constraint of positive power and modulation mode allocation is solved by null transmission on those deep-faded subcarriers. Finally discrete modulation mode (0, QPSK, 16QAM and 64QAM) is used to approach the optimally allocated continuous modulation mode, and simulation results demonstrate that the capacity loss from this approaching is negligible and QoS is guaranteed.
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Received: 26 October 2001
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2003, Vol. 25 
