Performance Analysis of Early-HARQ for Finite Block-Length Packet Transmission

Traditional retransmission protocols require the receiver to decode the entire packet before sending feedback signals, which may not be a viable solution for ultra-reliable and low-latency communications (URLLC) as it may cause a significant delay. To address this issue, early hybrid automatic repeat request (E-HARQ) has been proposed as an alternative to reduce the processing time at the receiver and send the feedback signal as quickly as possible. In this work, we present a framework for analyzing the performance of ARQ protocols considering URLLC requirements for finite block-length packet transmission and use it to evaluate the performance of E-HARQ from an information theory perspective, comparing it to simple ARQ. The results show that this new class of retransmission protocols can significantly improve the performance of URLLC systems.