  Existing polar coding schemes for the two-user interference channel follow
the original idea of Han and Kobayashi, in which component messages are encoded
independently and then mapped by some deterministic functions (i.e.,
homogeneous superposition coding). In this paper, we propose a new polar coding
scheme for the interference channel based on the heterogeneous superposition
coding approach of Chong, Motani and Garg. We prove that fully-joint decoding
(the receivers simultaneously decode both senders' common messages and the
intended sender's private message) in the Han-Kobayashi strategy can be
simplified to two types of partially-joint decoding, which are friendly to
polar coding with practical decoding algorithms. The proposed coding scheme
requires less auxiliary random variables and no deterministic functions, and
can be efficiently constructed. Further, we extend this result to interference
networks and show that the proposed partially-joint decoding scheme is a
general method for designing heterogeneous superposition polar coding schemes
in interference networks.
