The symmetric ergodic capacity of phase-fading interference channels to within a constant gap: 3 users in the strong and very strong regimes

Consider a three-user time-varying Gaussian interference channel under uniform phase fading. Prior work on ergodic interference alignment has shown that each user can simultaneously achieve half its interference-free rate. In this paper, we combine ideas from ergodic alignment and compute-and-forward to characterize the symmetric ergodic capacity of this channel in the strong and very strong regimes to within a constant gap.