Enabling the Multi-User Generalized Degrees of Freedom in Cellular Interference Networks with Multi-User Coding

Recent investigations have shown that multi-user gain can be enabled in frequency-flat, time-invariant, single-antenna interfering multiple access channels. This chapter will provide an overview of results, which lead to these recent key results. We will present conclusions of two deterministic approximation models and discuss the advantages and disadvantages. We start with results which were obtained with the linear deterministic model and show the necessity to use a richer model, the lower triangular deterministic model. Moreover, we shine a light on the connection to the interfering broadcast channel and therefore duality for the linear deterministic setting. We will see, that considerable multi-user gain can be enabled through signal-scale based coding in both deterministic approximations. We show that the multi-user gain of the linear deterministic model can be achieved in the Gaussian model as well, but is not optimal at all points. At the end, we discuss the possible transfer to Gaussian channels and give an outlook on ongoing research into the lower triangular deterministic model, where the upper bound can be reached at all points.