AG Kommunikationstheorie


Thema:

Power and Rate Allocation for Heterogeneous Transmission in Wireless Multiuser OFDM Systems

Abstract:

In the thesis, resource allocation problems for heterogeneous services in multiuser orthogonal frequency division multiplex (OFDM) systems are investigated. Given the total transmission power limit, the goal is to maximize the data rate of rate-adaptive services while satisfying the rate requirements for margin-adaptive services. Fairness among rate-adaptive services are additionally considered. Towards this, we firstly go over the necessary background knowledge from wireless communications and optimization theory that is related to the tasks. Then, optimization problems are formulated mathematically. The dual optimum solutions are derived for the concerning problems. However, since the complexity of the dual method is still too high to be applied in practical systems, heuristic methods are proposed to balance the computational efficiency and the performance. In the proposed heuristic method, the resources, consisting of subcarriers and transmit power, are adaptively allocated to the users according to their service requirements and channel conditions over two sequential steps. First, the rate requirements for margin-adaptive and rate-adaptive services are fulfilled with the minimized resource usage. Then, the remaining resource is allocated to the rate-adaptive services in order to maximize their total data rate. Simulations show that the proposed heuristic method has much lower computational complexity with small performance loss compared to the dual method.



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