Sparse Superimposed Vector Transmission for Short-Packet High-Mobility Communication

A sparse superimposed vector transmission (SSVT) scheme is proposed for short-packet ultra-reliable and low-latency communications (URLLC) in high-mobility scenarios. Unlike conventional pilot-less sparse vector coding (SVC) schemes, a small number of pilots are superimposed on top of data vector in SSVT to track time-varying channels, leading to high spectral efficiency. Two joint channel estimation and data decoding algorithms, called iterative interference cancellation (IIC) and iterative data-aided (IDA), are proposed to recover data from the received signal. The IIC algorithm accurately decodes data by iteratively canceling pilot and data interference, while the IDA algorithm further refines channel estimation by treating previously decoded data as pseudo-pilots. Simulation results show that the proposed SSVT scheme significantly outperforms conventional SVC schemes in terms of block error rate (BLER), and the proposed IIC and IDA algorithms show fast convergence speed.