On the Design of Analog Fountain Codes for Short Packet Communications in 5G URLLC

In this paper we consider the design of Analog fountain code (AFC) for 5G ultra-reliable and low latency communications (URLLC). We particularly focus on the design of the precoder which is shown to significantly affect the overall performance of the AFC in the short block length regime. We consider BCH codes as the precoder, and determine the rate of the code in order to maximize the realized rate under a given block error rate constraint. Simulation is performed to investigate the effect of choices for BCH precoder on the overall performance of BCH-AFC in terms of reliability and latency. We show that by selecting the appropriate BCH code as the AFC precoder, AFC performs closely to the normal approximation benchmark. We further proposed a threshold-based decoder to reduce the decoding complexity which is of significant importance in URLLC scenarios.