Optimization of Time Domain Windowing and Guardband Size for Cellular OFDM Systems

OFDM signals have sidelobes in the spectrum, causing interference to the neighboring frequency channels in a cellular system. The sidelobes can be suppressed by raised cosine (RC) windowing in time domain, while the inter-cell interference can be suppressed by reserving a guardband between neighboring frequency channels. A higher roll-off factor (ROF) of the RC window leads to better sidelobe suppression and allows a smaller guardband size, increasing the spectral efficiency. However, higher ROF implies longer symbol duration and reduced data rate. Therefore, there exist a tradeoff between the ROF and the guardband size. In this paper, a joint optimization technique for the ROF and guardband size is presented, which maximizes the data rate.