Simplified Han-Kobayashi region for one-sided and mixed Gaussian interference channels

The Han-Kobayashi (HK) encoding scheme is simplified for the one-sided Gaussian interference channel and a class of mixed interference channels, with Gaussian codebooks. The simplified region significantly decreases the computational complexity of the HK region. It also provides better insight into how to use the HK scheme for these channels. It shows that time-sharing with power allocation over two dimensions is enough to achieve the border of the HK inner bound, for these channels. Moreover, a new representation of the HK region for these channels is introduced.