HARQ Timing Configuration for Flexible Wireless Communication
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Solution Overview
Problem
Future wireless communication systems, such as LTE-A, require flexible HARQ timing relationships due to diverse UE capabilities and reduced decoding processing times, necessitating a heterogeneous HARQ timing approach that differs from conventional systems.
Innovation Solution
A method and apparatus for performing HARQ in a wireless communication system, where data is transmitted with a selected second transmission time interval from a set of predetermined intervals, allowing for flexible acknowledgement and retransmission timing, enabling heterogeneous HARQ processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional fixed HARQ period of 8 subframes is used, then system compatibility and simplicity are maintained, but flexibility to adapt to diverse UE capabilities and reduced decoding processing times is lost
Solution Approach 1:
The patent applies dynamics by making the HARQ period configurable rather than fixed. The base station can dynamically select from multiple predetermined HARQ periods (e.g., 4, 5, 6, 7, 8, 9, 10 subframes) based on UE capabilities and network conditions. This allows the system to adapt HARQ timing flexibly while maintaining a manageable configuration framework through pre-defined options and RRC signaling.
Solution Approach 2:
The patent implements parameter changes by introducing multiple configurable HARQ period parameters. Instead of a single fixed 8-subframe period, the system allows changing the HARQ period parameter to match different UE capabilities and processing speeds. The base station configures appropriate HARQ period values through RRC signaling, enabling parameter optimization without system redesign.
2Productivity
If heterogeneous HARQ timing relationships are implemented to support diverse UE capabilities, then adaptability improves, but system complexity and signaling overhead increase
Solution Approach 1:
The patent applies segmentation by dividing the HARQ configuration into multiple independent parameters including HARQ period, ACK/NACK transmission timing, and retransmission timing. Each parameter can be independently configured based on UE capabilities. This segmentation allows flexible customization of HARQ timing without requiring complete redesign of the HARQ mechanism, thus improving transmission efficiency while managing complexity through modular configuration.
Solution Approach 2:
The patent implements universality by designing a configurable HARQ framework that can accommodate multiple UE capabilities and network scenarios through a unified RRC signaling mechanism. The same base station and UE architecture can support both conventional fixed HARQ (8 subframes) and various heterogeneous HARQ configurations, making the system multi-functional and adaptable to different productivity requirements without increasing fundamental system complexity.
3Loss of time
If shorter HARQ periods are used to reduce latency, then transmission speed improves, but decoding processing time requirements become more stringent
Solution Approach 1:
The patent addresses this contradiction through parameter changes by allowing the HARQ period to be configured based on UE decoding capabilities. For UEs with faster processing, shorter HARQ periods (e.g., 4-6 subframes) can be selected to reduce latency. For UEs requiring more processing time, longer periods (e.g., 8-10 subframes) are configured to maintain decoding precision. This parameter-based adaptation optimizes both time loss and processing precision according to actual UE capabilities.
4Reliability
If longer HARQ periods are used to accommodate relay stations and MIMO, then reliability improves, but transmission latency increases
Solution Approach 1:
The patent applies dynamics by enabling the base station to dynamically select HARQ period lengths based on the specific communication scenario. For relay stations and MIMO configurations requiring higher reliability, longer HARQ periods are configured to ensure proper acknowledgment reception. For direct UE communications where latency is critical, shorter periods are used. This dynamic adaptation allows the system to optimize the reliability-latency tradeoff for different operational contexts.
Data Source
AI summary
A method of performing hybrid automatic repeat request (HARQ) by a source station in a wireless communication system is provided. The method includes: transmitting data to a destination station at a transmission start time; receiving an acknowledgment (ACK) or negative-acknowledgement (NACK) signal for the data from the destination station after a first transmission time interval elapses from the transmission start time; and upon receiving the NACK signal, retransmitting the data after a second transmission time interval elapses from the transmission start time, wherein the second transmission time interval is one transmission time interval selected from a plurality of predetermined transmission time intervals. Accordingly, the wireless communication system can perform a heterogeneous HARQ process in which an HARQ period, an ACK/NACK transmission start time, and the like are different.