Throughput comparison between VSF-OFCDM and OFDM considering effect of sectorization in forward link broadband packet wireless access

This paper compares the forward link radio link capacity between variable spreading factor-orthogonal frequency and code division multiplexing (VSF-OFCDM) with one-cell frequency reuse and orthogonal frequency division multiplexing (OFDM) with conventional three-cell frequency reuse or with one-cell frequency reuse utilizing symbol repetition, considering the effect of sectorization and the adaptive modulation and channel coding (AMC) scheme in a multi-cell environment in a broadband multipath fading channel. Simulation results demonstrate that, although the achievable radio link capacity in VSF-OFCDM is approximately 1.5 fold greater compared to that in OFDM with three-cell frequency reuse, almost identical radio link capacity under full channel-load conditions is realized in VSF-OFCDM and OFDM with one-cell frequency reuse applying elaborate symbol repetition transmission to suppress other-cell interference. Meanwhile, to achieve a lower data rate channel than the peak rate, higher-quality transmission is possible in VSF-OFCDM employing two-dimensional spreading compared to OFDM, by utilizing the frequency diversity effect in frequency domain spreading. Consequently, we conclude that VSF-OFCDM is superior to OFDM in broadband wireless access, since the former provides higher-quality transmission and more flexible accommodation of the lower data rate channels, along with the flexibility in designing essential channels such as the control and pilot channels.