Interference Management without CSIT: A Broadcast Approach

Abstract

Effective interference management in the multiuser interference channel strongly hinges on the availability of the channel state information at the transmitters (CSIT). In a broad range of emerging large-scale and distributed networks (e.g., the Internet of Things), however, acquiring the CSIT is prohibitive, due to the extensive information exchange that it imposes. In such circumstances, as a result, the interference management approaches that rely on the CSIT lose their effectiveness. This paper focuses on the two-user interference channel, and proposes a broadcast approach to interference management. Its hallmark is that the transmitters, unlike the receivers, are completely oblivious to instantaneous channel states. Each transmitter splits its message into multiple superimposed encoded information layers, where each layer is adapted to a given possible state for the combined states of all channels. Depending on the relative strengths of the direct and interfering channels, each receiver opportunistically decodes a subset of the received layers from both transmitters. An average achievable rate region is delineated serving as an inner bound on the average capacity region of the Gaussian interference channel in the absence of CSIT. Finally, it characterizes the gap between the achievable average sum-rate and the sum-rate capacity with the full CSIT in the asymptote of high signal-to-noise ratio. Numerical evaluations show that the cost of lacking CSIT is often insignificant.

Broadcast Approach to Uplink NOMA: Queuing Delay Analysis

“…This is generally referred to as the broadcast approach [ 12 ]. Furthermore, the studies in [ 13 ] extended the broadcast approach to the energy harvesting settings, those in [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ] to random and multi-access channel models, and those in [ 21 , 22 ] to the multiuser interference channel. Aside from analyzing the achievable rate regions of multi-layer superposition coding [ 17 , 23 ], the average delay performance has only been studied for the single-user fading channel in [ 24 ].…”