Iterative Detection and Decoding of Finite-Length Polar Codes in Gaussian Multiple Access Channels [article]

Moustafa Ebada, Sebastian Cammerer, Ahmed Elkelesh, Marvin Geiselhart, Stephan ten Brink
2020 arXiv   pre-print
We consider the usage of finite-length polar codes for the Gaussian multiple access channel (GMAC) with a finite number of users. Based on the interleave-division multipleaccess (IDMA) concept, we implement an iterative detection and decoding non-orthogonal multiple access (NOMA) receiver that benefits from a low complexity, while scaling (almost) linearly with the amount of active users. We further show the conceptual simplicity of the belief propagation (BP)-based decoder in a step-by-step
more » ... ustration of its construction. Beyond its conceptual simplicity, this approach benefits from an improved performance when compared to some recent work tackling the same problem, namely the setup of finite-length forward errorcorrection (FEC) codes for finite-number of users. We consider the 5th generation mobile communication (5G) polar code with a block length N = 512 applied to both a two-user and a four-user GMAC scenario with a sum-rate of R_sum = 0.5 and R_sum = 1, respectively. Simulation results show that a BP-based soft interference cancellation (SoIC) receiver outperforms a joint successive cancellation (JSC) scheme. Finally, we investigate the effect of a concatenated repetition code which suggests that alternative polar code design rules are required in multi-user scenarios.
arXiv:2012.01075v2 fatcat:ckll7r4wqbf3tplcpgrn6fzg3u