Parallelized Block-Based Distribution Matching

Probabilistic shaping (PS) techniques, when combined with forward error correction, enable reliable transmission at rates close to capacity by inducing a favorable probability distribution on channel input symbols. In this paper, we introduce the parallelized block-based distribution matching (PB-DM) shaping architecture. To facilitate high-throughput PS, the method operates by combining blocks of bits, generated in parallel by multiple binary distribution matchers, and mapping them to blocks of symbols from a non-binary alphabet. The sizes of bit and symbol blocks, and the mapping rule between such blocks, are key design parameters. The parameters bestow the PB-DM architecture with a high degree of customizability, which distinguishes it from other PS schemes. In particular, different PB-DM instances - each characterized by a particular trade-off between shaping performance, latency and memory footprint - can be constructed. Considering a scenario in which constraints are imposed on the allowable latency and memory usage, we propose a heuristic approach to determine design parameters that produce well-performing PB-DM schemes that satisfy the given constraints. We present simulation results over the additive white Gaussian noise channel, demonstrating the performance-complexity trade-offs realizable by different short-blocklength PB-DM designs, and compare them against the trade-offs achieved by other commonly used schemes.