An Inner Bound of Capacity Region for the Gaussian Interference Channel

An inner bound of capacity region for the Gaussian interference channel is derived using Sato´s modified frequency division multiplexing idea (Sato, 1978) and a special case of Han and Kobayashi´s rate region (denoted by G´ in Han and Kobayashi (1981)). We show that the new inner bound includes G´, Sason´s rate region D (Sason, 2004), as well as the achievable region via TDM/FDM (Carleial, 1978), as its subsets. The advantage of this improved inner bound over G´ arises due to its inherent ability to utilize the whole transmit power range on the real line without violating the power constraint. We also provide analysis to show that the new achievable region strictly extends G´ if max(R₁, R₂)_isinG´{R₁ + kR₂} is nonconcave for some k isin 0, +infin, where R₁ and R₂ are the rates of the two users.