Optimal resource allocation in SDMA/multiinput-single-output/OFDM systems under QoS and power constraints

This paper considers the resource allocation in space-division multiple access (SDMA)/multiinput-single-output (MISO)/OFDM downlink transmission system. Our objective function is to maximize the total system data rate subject to total power constraint and each user´s quality-of-service (QoS) requirement The QoS requirement can be BER requirement or SER requirement for any modulation schemes. Our earlier results in (Y. M. Tsang et al., 2004) showed that a significant improvement on total data rate can be obtained by optimizing the number of users in each subcarrier of the system. However, the solution presented in (Y. M. Tsang et al., 2004) is suboptimal. In this paper, we will exploit the properties of this rate maximization problem to reformulate it as a convex optimization problem and obtain the optimal solution.