Two-user Gaussian interference channels: An information theoretic point of view

The purpose of this monograph is to introduce up-to-date capacity theorems for the two-user Gaussian interference channel, including both single-antenna and multiple-antenna cases. The monograph starts with the single antenna case and introduces the Han and Kobayashi achievable rate region and its various subregions. Several capacity outer bounds are then presented; these outer bounds, together with the achievable rate region, yield several capacity results for the single-antenna Gaussian interference channel. They include the capacity region for strong interference and the sum-rate capacity for Z interference, noisy interference, mixed interference, and degraded interference. For the more complex multiple-antenna case, the interference state is no longer determined solely by the interference strength, as is the case for the single-antenna Gaussian interference channel. Instead, the structure of the interference in different multi-dimensional subspaces plays an equally important role. As a result of this multiple-dimensional signaling, new interference states, including generally strong, generally noisy, and generally mixed interference, are introduced to obtain capacity theorems that generalize those for the single-antenna case.