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

• Published in: 2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall) pp. 1 - 5
• Main Authors: Lim, Wen Jun, Shirvanimoghaddam, Mahyar, Abbas, Rana, Li, Yonghui, Vucetic, Branka
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.09.2019
• Subjects: AWGN channels; Complexity theory; Maximum likelihood decoding; Reliability; Signal to noise ratio
• ISSN: 2577-2465
• DOI: 10.1109/VTCFall.2019.8891550

Analog fountain code (AFC) is a seamless rate adaptation strategy and was recently shown to closely approach the channel capacity without the channel state information at the transmitter side. The code was mainly designed for large block lengths and therefore the design for short packet communications which is one of the communication scenarios in 5G ultra-reliable and low latency communications (URLLC), is still not clear. We tackle this problem in this work and particularly focus on the design of the precoder which is shown to significantly affects 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.