Hybrid ARQ Schemes
Amitav Mukherjee · Wiley 5G Ref · 2020
Abstract Hybrid automatic repeat request (HARQ) is a fundamental feature of modern mobile broadband networks such as fourth‐generation Long‐Term Evolution (LTE) and fifth‐generation New Radio (NR). HARQ schemes leverage a combination of error‐correction coding, error detection, and coherent combining of time‐domain repetitions to ensure reliable and robust delivery of data packets. This article provides an overview of general HARQ principles. This is followed by a detailed analysis of the HARQ mechanisms in LTE and NR and how HARQ feedback is generated and transmitted on uplink control channels.