The Han-Kobayashi region for a class of Gaussian interference channels with mixed interference

A simple encoding scheme based on Sato´s non-naive frequency division is proposed for a class of Gaussian interference channels with mixed interference. The achievable region is shown to be equivalent to that of Costa´s noiseberg region for the onesided Gaussian interference channel. This allows for an indirect proof that this simple achievable rate region is indeed equivalent to the Han-Kobayashi (HK) region with Gaussian input and with time sharing for this class of Gaussian interference channels with mixed interference.