Information-theoretic considerations for symmetric, cellular, multiple-access fading channels. I

A simple idealized linear (and planar) uplink cellular multiple-access communication model, where only adjacent cell interference is present and all signals may experience fading, is considered. Shannon theoretic arguments are invoked to gain insight into the implications on performance of the main system parameters and multiple-access techniques. We specialize to the linear model and address the case of practical importance where the cell-site receiver processes only the signals received at this cell site, and where the actively interfering users assigned to other cells (but not those within the cell) are interpreted as Gaussian noise (worst case assumption). We assume that the cell-site receiver is aware of the instantaneous signal-to-noise ratios for all users assigned to that cell while the users' transmitters do not have access to this side information. We first investigate several different scenarios and focus on the effect of fading and intercell interference and then provide a general formulation for an achievable rate region (inner-bound) of which all the different scenarios are special cases. The features of TDMA and wideband (WB) intracell multiple-access techniques are examined as well as the role of (optimized) fractional intercell time-sharing (ICTS) protocol. The cases of: no fading, fading where intercell interference is not dominant, and fading where intercell interference is present, are discussed.