A Utility-Based TMCR Scheduling Scheme for Downlink Multiuser MIMO-OFDMA Systems

Abstract

In this paper, a utility-based throughput maximization and complexity-reduction (U_TMCR) scheduling scheme is proposed for downlink multiuser multiple-input-multiple-output orthogonal frequency-division multiple-access (MIMO-OFDMA) systems. The U_TMCR scheme allocates subchannels, antenna sequence, and modulation order to multimedia users with goals not only to maximize system throughput under quality-of-service (QoS) guarantee but to reduce computational complexity as well. Based on the channel quality and the QoS requirements of each user, the U_TMCR scheme designs a utility function for every user and formulates the scheduling into an optimization problem of overall system utility function subject to system constraints. It also contains a heuristic TMCR algorithm to efficiently solve the optimization problem. Simulation results show that the U_TMCR scheme achieves system throughput very close to the optimal solution by exhaustive search and higher than conventional schemes such as adaptive radio resource allocation (ARRA) and cross-layer design of packet scheduling (CDPS) by about 8% and 21%, respectively. The U_TMCR scheme also has a QoS satisfaction ratio that is better than the ARRA and CDPS schemes. Moreover, the U_TMCR scheme can reduce computational complexity. Generally, the total number of allocation trials of the U_TMCR scheme in a frame is smaller than that of the ARRA scheme by 6.25%-29.2%.