The Capacity Region Of Z-interference Channel With A Digital Communication Link

Research of Gaussian Z-interference channel and deterministic Z channel has a lot of guidanceand practical significance for wireless network communications. Firstly, it can enable the better useof the radio spectrum resources; Secondly, capacity regions of some channel models, which are thetheoretical limits of the transmission performance can be derived; Thirdly, it can improve theefficiency of the network information transmission; Finally, a variety of new methods、new conceptsand new ideas which come from multi-user information theory can be used in wireless networksystem, thereby can directly promote the wireless network communications technology forward.This paper firstly considers a2-user Gaussian Z-interference channel with a noiseless andbidirectional digital communication link between the receivers. The two receiving nodes areallowed to cooperate by means of the bidirectional noiseless link with finite capacity. Theachievable rate region is achieved by utilizing rate-splitting and superposition encoding technique.One of the key assumptions is that the conferencing link from the interference-free receiver to theinterfered receiver has sufficient capacity to accommodate the binning rate for the “private”message of the interference-free receiver, allowing for the successive decoding at the interferedreceiver.An outer bound for the Gaussian Z-interference channel researched above is derived and inthe very strong interference regime, the capacity region is achieved, which is identical to a recentresult by Zhou and Yu for a similar scenario, however, with a unidirectional communication linkbetween the receivers. Moreover, in the weak interference regime, the achievable rate region thispaper achieved includes the achievable rate region researched by Zhou and Yu for a unidirectionalcommunication link.In the following the paper considers a class of deterministic Z channels with a noiseless andunidirectional digital relay link between the receivers where two nodes want to send threeindependent messages to the other two nodes，and an outerbound for this model is derived. If we setW12to be zero, the outerbound here is identical to the capacity region achieved by Liu and Gunduzfor a similar scenario.