Space-division multi-access (SDMA) and Orthogonal Frequency Division Multiplexing (OFDM) have been considered as an effective solution to increase channel efficiency for supporting high data rate transmission in the future communication system. To further increase system throughput, resource allocation scheme should also be considered. Since the channel conditions in wireless communication system are varying, it is wasteful if the resources are allocated to channels with poor conditions. Hence, in this thesis, to fully utilize the system resources under the limitation of the scarce spectrum, we will integrate the SDMA with OFDM system and present an optimal way to allocate the resources algorithm in the systems....[ Read more ]

Space-division multi-access (SDMA) and Orthogonal Frequency Division Multiplexing (OFDM) have been considered as an effective solution to increase channel efficiency for supporting high data rate transmission in the future communication system. To further increase system throughput, resource allocation scheme should also be considered. Since the channel conditions in wireless communication system are varying, it is wasteful if the resources are allocated to channels with poor conditions. Hence, in this thesis, to fully utilize the system resources under the limitation of the scarce spectrum, we will integrate the SDMA with OFDM system and present an optimal way to allocate the resources algorithm in the systems.

In this thesis, we first present an opportunistic transmission scheme whose objective function is to maximize the total system data rate subject to total power constraint and each user's Quality-of-Service (QoS) requirement. We try looking at the problem from different angles and re-formulate the hard maximization problem into a convex optimization problem and obtain the optimal solution. Through a careful observation of the solution, a fast-converging but complexity-manageable algorithm is derived. Simulation shows that our proposed algorithm outperforms all the existing schemes within a few iterations.

We further extend the opportunistic transmission scheme for fair transmission and multimedia transmission. The opportunistic scheme basically allocates all resource to the users with best channel conditions, not allowing the users with poor channel gains to transmit. This is unfair to the latter. Also, the opportunistic transmission scheme does not have data rate guarantee. Sometimes, users may get higher rates but at later times they may get zero rates. This fluctuation in the data rate is not suitable for multimedia transmission. To tackle the above problems, we will propose an optimal resource allocation algorithm with minimum rate guarantee.