HARQ Feedback Timing for Early Unresponsive UE Release
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Solution Overview
Problem
Existing cellular communication systems face challenges in detecting unresponsive user equipment (UE), leading to inefficient use of radio resources and battery drain due to continuous data transmission to non-responsive UEs, and prolonged detection times for radio link failures.
Innovation Solution
Implementing a method to detect unresponsive UE using Hybrid Automatic Repeat Request (HARQ) feedback, where a gNB initiates a UE release transaction upon expiration of a timer (T_HARQ_DTX) if consecutive HARQ feedback is not received, based on parameters n310, t310, and T_EVALUATE_OUT_SSB, indicating poor channel quality or loss of synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous data transmission is performed to user equipment, then communication service is maintained, but radio resources are wasted and battery drain occurs when the equipment is unresponsive
Solution Approach 1:
The system performs preliminary detection by monitoring HARQ feedback before declaring a radio link failure. A timer (T_HARQ_DTX) is started when HARQ feedback is not received, and only after this timer expires does the system initiate the release procedure. This preliminary action allows the system to distinguish between temporary transmission issues and actual unresponsive equipment, releasing resources only when necessary.
2Reliability
If traditional radio link failure detection methods are used, then unresponsive user equipment is detected, but detection time is prolonged leading to delayed resource release
Solution Approach 1:
The system starts a timer (T_HARQ_DTX) immediately when HARQ feedback is not received, performing the detection action in advance. This timer-based preliminary detection mechanism allows the system to quickly identify unresponsive equipment without waiting for traditional RLC or higher-layer protocols, significantly reducing detection time while maintaining reliability through the configured timer threshold.
Solution Approach 2:
The system changes the detection parameter from traditional RLC-level or higher-layer acknowledgments to HARQ feedback timing. By monitoring whether HARQ feedback is received within a specific time window (T_HARQ_DTX) and using configurable parameters (n310, t310, T_EVALUATE_OUT_SSB), the system achieves faster detection with adjustable sensitivity, optimizing the balance between detection speed and accuracy.
3Productivity
If HARQ feedback monitoring is implemented with timer-based detection, then unresponsive user equipment is detected early, but system complexity increases
Solution Approach 1:
The system uses the existing HARQ feedback mechanism, which is already part of the standard cellular protocol stack, for dual purposes: both for data transmission acknowledgment and for detecting unresponsive equipment. The same HARQ processes and timing mechanisms used for normal communication are repurposed for detection, avoiding the need for separate detection infrastructure and minimizing additional complexity.
Solution Approach 2:
The system leverages its own existing timing and monitoring infrastructure to perform detection. The timer mechanism (T_HARQ_DTX) uses the same time-synchronization and counting capabilities already present for HARQ operation. The system essentially monitors its own communication state using built-in resources, eliminating the need for external detection devices or complex additional processing systems.
Data Source
AI summary
A system can communicate broadband cellular communications with a user equipment. The system can perform iterations of scheduling downlink data for the user equipment as part of the broadband cellular communications. The system can, in response to determining that hybrid automatic repeat request feedback, which corresponds to downlink data of the iterations of scheduling downlink data, has not been received within a defined time period, initiate a user equipment release transaction with regard to the user equipment, and send a user equipment context release request to a centralized unit of a base station of the system.