Configured Grant HARQ Timer Management in NR-U
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Solution Overview
Problem
In the context of New Radio (NR) unlicensed spectrum operations, there are challenges in managing timers and pending transmission blocks (TBs) associated with non-idle Hybrid Automatic Repeat Request (HARQ) processes during configured grant activation, reactivation, or deactivation, which affects configuration flexibility, resource utilization, and Quality of Service (QoS) satisfaction for different services sharing resources, as well as causing misalignment between gNB and UE in terms of NDI and timer states.
Innovation Solution
Introducing new timers and procedures for handling configured grants, such as the configuredGrantTimer and CGretransmissionTimer, to manage retransmissions, prioritize HARQ processes, and align UE and gNB states, allowing for flexible configuration and improved resource management, including autonomous retransmissions and handling of multiple active configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If new timers and procedures are introduced to manage HARQ processes during configured grant activation, then configuration flexibility and resource utilization are improved, but device complexity increases
Solution Approach 1:
The patent segments the HARQ management process by introducing separate timers (configuredGrantTimer and CGretransmissionTimer) for different functional purposes. The configuredGrantTimer manages the overall configured grant activation state, while the CGretransmissionTimer specifically handles retransmission operations. This segmentation allows independent control of different HARQ management aspects, improving configuration flexibility without requiring complete redesign of the entire HARQ mechanism.
Solution Approach 2:
The patent implements preliminary action by pre-configuring timer parameters and HARQ process states before actual transmission occurs. The configuredGrantTimer is activated in advance to prepare the system for potential retransmissions, and HARQ process IDs are pre-allocated and tracked. This preliminary setup enables rapid response to transmission failures without requiring complex real-time decision-making, thus improving resource utilization while keeping device complexity manageable.
2Productivity
If timers are maintained for non-idle HARQ processes during CG activation, then resource utilization improves, but misalignment between gNB and UE increases
Solution Approach 1:
The patent implements feedback mechanisms where the UE monitors the configuredGrantTimer and CGretransmissionTimer states and reports HARQ process status to the gNB. The gNB similarly tracks these timers and uses the feedback to synchronize its understanding of the HARQ process states. This bidirectional feedback ensures that both gNB and UE maintain consistent views of which timers are active and which HARQ processes are non-idle, preventing misalignment while allowing continuous resource utilization.
Solution Approach 2:
The patent creates equipotentiality by ensuring that both gNB and UE operate from the same timer configuration parameters and state machine definitions. The configuredGrantTimer and CGretransmissionTimer are configured with identical parameters at both ends, and the same timer management logic is applied. This equipotential operating condition ensures that when the UE maintains timers for non-idle HARQ processes, the gNB simultaneously maintains corresponding timers, eliminating state misalignment while maximizing resource utilization.
3Reliability
If HARQ processes are prioritized and managed with multiple timers, then QoS satisfaction improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different timer characteristics and priorities to different HARQ processes based on their QoS requirements. High-priority services (e.g., ultra-reliable low-latency communications) are assigned shorter timer values and higher priority handling, while best-effort services use longer timer values. The configuredGrantTimer and CGretransmissionTimer are selectively applied to specific HARQ processes based on their QoS class, allowing differentiated QoS satisfaction without requiring complete complexity for all processes.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting timer values and HARQ process priorities based on service type and QoS requirements. The configuredGrantTimer duration and CGretransmissionTimer thresholds are configured as adjustable parameters that can be modified according to the active service's QoS needs. This parameter-based control allows the system to optimize QoS satisfaction for different services without requiring fundamentally different timer mechanisms, thereby managing device complexity through configurable parameters rather than hard-coded complex logic.
Data Source
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AI summary
A wireless device operating in a communication network can, responsive to receiving a downlink control indication ("DCI") command to activate or reactivate a configured grant ("CG") configuration that is associated with a first transmission block ("TB") having a first transmission block size ("TBS"), handling a non-idle hybrid automatic repeat request ("HARQ") process on the CG configuration based on whether the first TBS is different than a second TBS of a second TB associated with the non-idle HARQ process. The non-idle HARQ process can include a process of retransmitting the second TB using the CG for which an associated media access control ("MAC") protocol data unit ("PDU") has been submitted to lower layers for transmission to a network node, but for which successful reception acknowledgment has not been received from the network node.