Extended Generalized DoF Optimality Regime of Treating Interference as Noise in the X Channel

The simple scheme of treating interference as noise (TIN) is studied in this paper for the 3 x 2 X channel. A new sum-capacity upper bound is derived. This upper bound is transformed into a generalized degrees-of-freedom (GDoF) upper bound, and is shown to coincide with the achievable GDoF of scheme that combines TDMA and TIN for some conditions on the channel parameters. These conditions specify a noisy interference regime which extends noisy interference regimes available in literature. As a by-product, the sum-capacity of the 3 x 2 X channel is characterized within a constant gap in the given noisy interference regime.