BER analysis of variable sub-carrier bandwidth OFDMA systems

OFDMA is the preferred multiple access technique to provide high data rate services in mobile environment due its resilience against multipath propagation impairment and flexibility to provide multi-rate data services. However, it also has issue with susceptibility to ICI (inter-carrier interference) caused by frequency offset and Doppler spread due to mobility. Thus, OFDMA with certain number of sub-carriers will only be optimum over a certain range of mobility. Recently, a VSB-OFDMA (variable sub-carrier OFDMA), system has been proposed to relax the effect of ICI. Although it suffers from non-orthogonality caused by different sub-carrier sizes, as ICI is inversely proportional to the sub-carrier bandwidth, it rakes in benefit from reduced ICI in mix-mobility environment. It has been shown to produce higher system capacity under mix-mobility environment. In this paper we have performed comparison based on computer simulation to gauge the advantage offered by VSB-OFDMA in terms of BER.