A Blind Interference Management Technique for the K-User Interference Channel with ISI: Interference-Free OFDM

This paper considers a K-user single-input-single-output interference channel with inter-symbol interference (ISI), in which the channel coefficients are assumed to be linear time-invariant with finite-length impulse response. The primary finding of this paper is that, with no channel state information at a transmitter (CSIT), the sum-spectral efficiency can be made to scale linearly with K, provided that the desired links have longer impulse response than do the interfering links. This linear gain is achieved by a novel multi-carrier communication scheme which we call interference-free orthogonal frequency division multiplexing (IF-OFDM). A major implication of the derived results is that separate encoding across subcarriers per link is sufficient to linearly increase the sum-spectral efficiency with K in the interference channel with ISI. Simulation results support this claim.