tailieunhanh - Báo cáo hóa học: " Research Article Joint Throughput Maximization and Fair Uplink Transmission Scheduling in CDMA Systems"

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 Joint Throughput Maximization and Fair Uplink Transmission Scheduling in CDMA Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 564692 15 pages doi 2009 564692 Research Article Joint Throughput Maximization and Fair Uplink Transmission Scheduling in CDMA Systems Symeon Papavassiliou1 2 and Chengzhou Li3 1Network Management and Optimal Design Laboratory NETMODE Institute of Communications and Computer Systems ICCS 9 Iroon Polytechniou Street Zografou 157 73 Athens Greece 2School of Electrical and Computer Engineering National Technical University of Athens NTUA 9Iroon Polytechniou Street Zografou 157 73 Athens Greece 3LSI Corporation 1110 American Parkway NE Allentown PA 18109 USA Correspondence should be addressed to Symeon Papavassiliou papavass@ Received 9 July 2008 Revised 10 December 2008 Accepted 20 February 2009 Recommended by Alagan Anpalagan We study the fundamental problem of optimal transmission scheduling in a code-division multiple-access wireless system in order to maximize the uplink system throughput while satisfying the users quality-of-service QoS requirements and maintaining fairness among them. The corresponding problem is expressed as a weighted throughput maximization problem under certain power and QoS constraints where the weights are the control parameters reflecting the fairness constraints. With the introduction of the power index capacity it is shown that this optimization problem can be converted into a binary knapsack problem where all the corresponding constraints are replaced by the power index capacities at some certain system power index. A two-step approach is followed to obtain the optimal solution. First a simple method is proposed to find the optimal set of users to receive service for a given fixed target system load and then the optimal solution is obtained as a global search within a certain range. Furthermore a stochastic approximation method is presented to effectively identify the required control parameters. The .