Hybrid Automatic Repeat Request Protocols in Wireless Communication Systems
Summary
Hybrid Automatic Repeat Request (HARQ) protocols blend error-detection and error-correction techniques to improve reliability and spectral efficiency in modern wireless networks. By combining forward error correction with selective retransmission, HARQ schemes can dynamically exploit time, frequency and spatial diversity. Chase combining HARQ repeats the same coded packet upon detection of errors, offering simplicity at the cost of throughput, whereas incremental redundancy HARQ transmits complementary parity information across multiple rounds, enhancing coding gain. These protocols underpin the reliability of cellular standards such as LTE and 5G New Radio, support ultra-reliable low-latency communications for industrial automation, and facilitate energy-constrained Internet of Things deployments. Advances in adaptive power allocation, cross-layer feedback and multi-antenna designs have further refined HARQ performance, enabling its application in satellite links, unmanned aerial vehicle networks and full-duplex relay systems. The global significance of HARQ lies in its ability to balance throughput, latency and energy consumption, making it a cornerstone of next-generation wireless ecosystems.
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Hybrid Automatic Repeat Request Protocols in Wireless Communication Systems publication trend
The graph below shows the total number of articles in hybrid automatic repeat request protocols in wireless communication systems across all publications each year (not limited to Nature Index journals).
Technical terms
Automatic Repeat Request (ARQ): An error-control method in which failed packets are retransmitted upon request.
Hybrid ARQ (HARQ): A protocol combining ARQ with forward error correction to improve reliability and efficiency.
Chase Combining (CC): A HARQ variant that retransmits identical coded packets and combines received signals to boost decoding.
Incremental Redundancy (IR): A HARQ strategy that sends additional parity bits in each retransmission to enhance coding gain.
Log-Likelihood Ratio (LLR): A metric representing the confidence of received bits, used in soft-decision decoding.
Multiple-Input Multiple-Output (MIMO): A technique employing multiple antennas at transmitter and receiver ends to exploit spatial diversity.
Simultaneous Wireless Information and Power Transfer (SWIPT): A framework in which energy and data are transmitted concurrently, enabling energy harvesting at the receiver.
References
- Performance Analysis of Hybrid ARQ for Ultra-Reliable Low Latency Communications. IEEE Sensors Journal (2019).
- Performance Evaluation of HARQ Schemes for the Internet of Things †. Computers (2018).
- Reliable and Energy-Efficient LEO Satellite Communication with IR-HARQ via Power Allocation. Sensors (2022).
- Post-Cancellation-Based LLR Refining for MIMO Multiple ARQ Systems. Electronics (2024).
- Throughput Analysis of HARQ Scheme Based on Full-Duplex Two-Way AF SWIPT Relay. Computers Materials & Continua (2023).
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