Research On Downlink Capacity For Broadband Wireless Access - VSFOFCDM

Variable spreading factor-orthogonal frequency and code division multiplexing (VSF-OFCDM) is not only a CDMA network, but also the integration of MC-CDMA, OFDM, VSF and time and frequency two-dimensional spreading code. The complicated configuration is a challenge to traditional CDMA network planning-capacity planning. Detailed theory analysis of capacity is proposed and we develop expression of capacity for VSF-OFCDM in downlink from the viewpoint of multi-cell and isolated-cell environment. Through extremum of a multivariate function, which is proposed by Lagrange multipliers, we get the maximum capacity of voice and data in downlink, respectively. Simulation results show that in downlink, throughput performance of voice can achieve 38.9 Mbit/s while the throughput performance of data can achieve 56.8 Mbit/s from the viewpoint of multi-cell. In isolated-cell environment, throughput performance of the whole system can reach higher capacity because of none other-sell interference