On the Generalized Degrees of Freedom of Noncoherent Interference Channel

We study the generalized degrees of freedom (gDoF) of the block-fading noncoherent 2-user interference channel (IC) with a coherence time of T symbol durations and symmetric fading statistics. We demonstrate that a natural training-based scheme, to operate the noncoherent IC, is suboptimal in several regimes. As an alternate scheme, we propose a new noncoherent rate-splitting scheme. We also consider treating interference-as-noise (TIN) scheme and a time division multiplexing (TDM) scheme. We observe that a standard training-based scheme for IC is outperformed by one of these schemes in several regimes: our results demonstrate that for low average interference-to-noise ratio (INR), TIN is best; for high INR, TDM and the noncoherent rate-splitting give better performance. We also study the noncoherent IC with feedback and propose a noncoherent rate-splitting scheme. Again for the feedback case as well, our results demonstrate that a natural training-based scheme can be outperformed by other schemes.Comment: Simplified the proof