Achieving Marton's Region for Broadcast Channels Using Polar Codes

We present polar coding schemes for the 2-user discrete memoryless broadcast channel (DM-BC) which achieve Marton's region with both common and private messages. This is the best achievable rate region up to date, and it is tight for all classes of 2-user DM-BCs whose capacity regions are known. Due to space limitations, this paper describes polar codes for the superposition strategy. The scheme for the achievability of Marton's region is presented in the longer version [1], and it is based on a combination of superposition coding and binning. We follow the lead of the recent work by Goela, Abbe, and Gastpar, who introduce polar codes emulating these two information-theoretic techniques. In order to align the polar indices, for both schemes, their solution involves some degradedness constraints that are assumed to hold between the auxiliary random variables and the channel outputs. To remove these constraints, we consider the transmission of k blocks, and employ chaining constructions that guarantee the proper alignment of polarized indices. The techniques described in this work are quite general, and they can be adopted in many other multi-terminal scenarios whenever there is the need for the aligning of polar indices.