On carrier nulling approaches for channel shortening in OFDMA systems

This paper considers blind and semiblind channel shortening methods based on carrier nulling criteria to mitigate the effect of inter-block interference in uplink OFDMA systems. We derive a sufficient condition that states that if the number of subcarriers unused by a desired user exceeds a given threshold then uplink channels can be shortened perfectly. Simulation results are shown to verify the analytical result.