HARQ Feedback Control for Speed and Reliability Trade-off
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Solution Overview
Problem
Current LTE systems face challenges with the reliability, flexibility, and speed of hybrid ARQ (HARQ) feedback procedures, particularly due to the inflexibility of the HARQ protocol and the overhead added by the higher layer RLC AM for ensuring reliability.
Innovation Solution
A method is introduced to selectively employ two HARQ feedback processes: a self-contained HARQ feedback process for faster feedback and a scheduled HARQ feedback process for more reliable feedback. The choice between these processes is based on the required level of reliability and timing constraints, allowing for a combination of both processes if both low latency and high reliability are needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a self-contained HARQ feedback process is used, then feedback speed is improved, but feedback reliability deteriorates
Solution Approach 1:
The feedback process is segmented into two distinct HARQ feedback processes: a self-contained process for fast feedback and a scheduled process for reliable feedback. This segmentation allows the system to select the appropriate process based on specific requirements, resolving the contradiction between speed and reliability by providing specialized paths for each objective.
Solution Approach 2:
The system dynamically selects between the self-contained and scheduled HARQ feedback processes based on real-time requirements for speed and reliability. This dynamic adaptability allows the system to optimize performance by choosing the most appropriate feedback mechanism for each specific transmission scenario.
2Stability of the object's composition
If the HARQ protocol uses strict timing relations, then feedback synchronization is improved, but system flexibility deteriorates
Solution Approach 1:
The system employs dynamic timing configurations for the scheduled HARQ feedback process, allowing timing relations to be adjusted based on specific communication scenarios. This dynamic approach maintains synchronization stability while providing the flexibility needed for different operational requirements.
3Reliability
If RLC AM layer is added to ensure reliability, then delivery reliability is improved, but protocol complexity and overhead increase
Solution Approach 1:
The invention extracts the reliability assurance function from the higher-layer RLC AM protocol and implements it directly within the MAC layer HARQ feedback processes. This extraction eliminates the need for the complex RLC AM layer while maintaining delivery reliability, as the dual HARQ feedback mechanisms provide sufficient reliability guarantees at the MAC layer.
4Stability of the object's composition
If synchronous HARQ timing operation is used, then feedback timing consistency is improved, but adaptability to dynamic TDD deteriorates
Solution Approach 1:
The system implements dynamic timing adjustments for the scheduled HARQ feedback process to adapt to different TDD configurations. This allows the system to maintain feedback timing consistency within each configuration while being adaptable to dynamic changes in TDD patterns, resolving the contradiction between consistency and adaptability.
Data Source
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AI summary
Methods and devices, particularly radio base station and communication terminal, for controlling a feedback process in a communication between nodes of a communication system, comprising selectively employing one or both of a first feedback process which provides fast feedback and a second feedback process which provides reliable feedback, wherein the first and second feedback processes operate at least partly on the same transmission buffers or queues.