On the symmetric capacity of the K-user symmetric cyclic Gaussian interference channel

The capacity region of Gaussian interference channel in the weak interference regime is an open problem. Recently, Etkin, Tse and Wang derived an outer bound for the two-user Gaussian interference channel and proved that a simple Han-Kobayashi signaling scheme can achieve within one bit of the capacity region for all values of channel parameters. In this paper, we extend their result to the K-user symmetric cyclic Gaussian interference channel. Our result shows that both the Etkin, Tse and Wang's upper bound and their one-bit achievability result on the symmetric rate continue to hold for the symmetric rate of the K-user symmetric cyclic channel using the same Han-Kobayashi strategy.