Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article CDIT-Based Constrained Resource Allocation for Mobile WiMAX Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 425367 8 pages doi 2009 425367 Research Article CDIT-Based Constrained Resource Allocation for Mobile WiMAX Systems Felix Brah Jerome Louveaux and Luc Vandendorpe Ecole Polytechnique de Louvain Universite Catholique de Louvain Place du Levant 2 1348 Louvain-la-Neuve Belgium Correspondence should be addressed to Felix Brah Received 1 July 2008 Accepted 31 October 2008 Recommended by Ekram Hossain Adaptive resource allocation has been shown to provide substantial performance gain in OFDMA-based wireless systems such as WiMAX when full channel state information CSI is available at the transmitter. However in some fading environments . fast fading there may not be a feedback link sufficiently fast to convey the CSI to the transmitter. In this paper we consider resource allocation strategies for downlink multiuser mobile WiMAX systems where the transmitter has only the channel distribution information CDI but no knowledge of the instantaneous channel realization. We address the problem of subchannel assignment and power allocation to maximize the ergodic weighted-sum rate under long-term fairness minimum data rate requirement and power budget constraints. This problem is formulated as a nonlinear stochastic constrained optimization problem. We provide an analytical solution based on the Lagrange dual decomposition framework. The proposed method has a complexity of Ỡ KM for K users and M subchannels. Simulation results are provided to compare the performance of this method with other allocation schemes and to illustrate the tradeoff between maximized weighted-sum rate and the constraints. Copyright 2009 Felix Brah et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly .
