A New Polar Coding Scheme for the Interference Channel.

We consider the problem of polar coding for the 2-user discrete memoryless interference channel (DM-IC) to achieve the Han-Kobayashi region, the best achievable rate region to date. Existing schemes are designed according to the original description of the Han-Kobayashi region, in which two deterministic functions that map auxiliary random variables to channel inputs are assumed to be known. Inspired by Chong et al.u0027s compact description of the Han-Kobayashi region, which uses joint distributions of random variables instead of deterministic functions, we find that the Han-Kobayashi region can be achieved in a simpler way. The original Han-Kobayashi strategy requires joint decoding of the intended senderu0027s private message and both sendersu0027 common messages at each receiver. In this paper, we show that all corner points of the Han-Kobayashi region can be achieved using partially joint decoders, i.e., each receiver only needs to jointly decode two of the three messages, either both sendersu0027 common messages, or the unintended senderu0027s common message and the intended senderu0027s private message. Based on this finding and enlightened by Goela et al.u0027s superposition polar coding schemes for the broadcast channels, we design two types of polar coding schemes, which can be seen as extensions of Carleialu0027s superposition coding scheme for the DM-IC with more powerful joint decoders, and show that every corner point can be achieved using one of the proposed schemes. The joint decoders and the corresponding code constructions are implemented using the 2-user multiple access channel (MAC) polarization technique based on Arikanu0027s monotone chain rule expansions, which has similar complexity to the single-user case. The chaining method which has already been widely used for constructing universal polar codes is adopted to solve the problem of alignment of polar indices.