Sparse Superimposed Coding for Short-Packet URLLC

Abstract

Sparse vector coding (SVC) is emerging as a key enabler for short packet ultra-reliable and low latency communications (URLLC), since it displays good block error rate (BLER) performance and can achieve low transmission latency. In this paper, we propose a SVC-based sparse superimposed transmission (SVC-ST) coding scheme to further enhance the BLER performance of SVC scheme. At the encoding side, a portion of transmission bits is represented by non-zero position indices of sparse vector. The remaining bits are equally split into multiple streams and then mapped into the non-zero positions of sparse vector via quadrature amplitude modulation (QAM) with constellation rotation (CR). We afterwards adopt the multipath matching pursuit-based soft decoding (MMP-SD) to recover the transmission packet. The BLER and bit error rate (BER) analysis of SVC-ST scheme demonstrate the validity and rationality of our study. Moreover, we find from the simulation results that the proposed SVC-ST scheme outperforms SVC and its enhanced version (ESVC) schemes in terms of BLER and latency performance.