Intercarrier Interference Suppression for OFDMA Uplink in Time and Frequency Selective Rayleigh Fading Channels

This paper investigates inter-carrier interference (ICI) suppression for the uplink of an orthogonal frequency division multiple access (OFDMA) system in a time and frequency selective Rayleigh fading channel. In such a doubly selective channel, channel variation within each OFDMA block disrupts the orthogonality among subcarriers, leading to ICI. We formulate the signal model for OFDMA uplink in a doubly selective Rayleigh fading channel, and then propose a MMSE and a MMSE successive detection (MMSE-SD) scheme to suppress ICI. It is shown that the MMSE scheme is the optimal linear scheme in terms of achievable data rate, while the MMSE-SD scheme is able to further remove ICI and exploit the Doppler diversity embedded in time-varying channels. Simulation results are presented to illustrate the performance improvements that can be obtained from using the proposed suppression schemes.