Multiple-Mode Sparse Superposed Code With Low Block Error Rate for Short Packet URLLC

Sparse superposed code (SSC) is one of the most promising techniques to support the ultra-reliable and low-latency communication (URLLC). Compared with the conventional sparse vector code (SVC), quadrature amplitude modulation (QAM) symbols are exploited to carry information bits in SSC. By such an approach, the dimension of the codebook in SSC can be significantly reduced, which results in a lower block error rate (BLER) of the multi-path matching pursuit (MMP)-based decoder. In similar spirit, a multiple-mode SSC (MSSC) is proposed to further reduce BLER. On the encoding side, the information bits are divided into three parts. The first two parts are the same as traditional SSC, while the remaining information bits are mapped as the permutation of the constellation alphabets. On the decoding side, an enhanced MMP-based decoder is developed, where the extra constellation alphabet permutation detection is realized. Simulation results reveal that the proposed MSSC outperforms the conventional SSC significantly.