A user-independent serial interference cancellation based coding scheme for the unsourced random access Gaussian channel

Abstract

We propose a novel coding scheme for the unsourced multiple access channel model introduced by Polyanskiy [1]. This new paradigm is composed of four main ingredients: (i) the transmission period is partitioned into sub-blocks, thereby instituting a slotted framework; (ii) The message (data) is split into two parts and one part chooses an interleaver for a low density parity check (LDPC) type code. This part of the message is encoded using spreading sequences or codewords that are designed to be decoded by a compressed sensing type decoder; (iii) The other part of the message is encoded using a low density parity check (LDPC) type code and decoded using a joint message passing decoding algorithm designed for the T-user binary input real adder channel; (iv) users repeat their codeword in multiple sub-blocks, with the transmission pattern being a deterministic function of message content and independent of the identity of the user. When this coding scheme is combined with serial interference cancellation, the ensuing communication infrastructure can offer significant performance improvements compared to the recently proposed coding scheme in [2] and results in the best performing coding scheme to date.