Throughput Maximization of Downlink MC-CDMA Systems
Motivated by the increasing popularity of multi- carrier code division multiple access (MC-CDMA) systems, this letter studies the throughput maximization of MC-CDMA as a downlink multi-carrier multiple-access scheme and presents the theoretical analysis for the optimal solution to throughput optimization problem of downlink MC-CDMA systems. Then, a low-complexity allocation method is proposed with negligible throughput loss. Finally, several resource allocation principles are presented. I. INTRODUCTION In the third-generation (3G) communication systems, code division multiple access (CDMA) (1)-(3) has been adopted as a major multiple access technique. Meanwhile, in a wideband channel, multi-carrier transmission realized by orthogonal frequency-division multiplexing (OFDM) has become popu- lar due to its robustness to multipath interference and high spectral efficiency. Therefore, CDMA has been considered to be involved with a multi-carrier transmission to exploit the benefits of the two techniques. Several multiple access schemes that combine CDMA and multi-carrier transmission have been proposed for the future fourth generation (4G) wireless communication systems (4). Among these schemes, multi-carrier code division multiple access (MC-CDMA) has drawn a lot of attention as a good candidate for the 4G