HARQ Codebook Generation for NTN Latency Optimization
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Solution Overview
Problem
The challenge in non-terrestrial networks (NTN) is the inefficiency of HARQ operation due to long round trip times (RTT), which increases the number of parallel HARQ processes required, leading to high latency and increased costs for retransmissions in latency-sensitive applications.
Innovation Solution
A method for performing HARQ codebook generation that excludes the HARQ state for PDSCH receptions with disabled HARQ feedback, allowing for dynamic configuration of HARQ-less operation and optimizing power control by adjusting the number of Uplink Control Information (UCI) bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ operation is enabled with long RTT in NTN, then reliability of data transmission is improved, but latency increases and operational costs increase
Solution Approach 1:
The patent applies dynamic configuration of HARQ operation based on service type and network conditions. The system can switch between HARQ-enabled and HARQ-less modes dynamically, allowing optimization of latency for latency-sensitive services while maintaining reliability for other services. This dynamic adaptation resolves the contradiction by making the system flexible rather than fixed.
Solution Approach 2:
The patent changes the operational parameters of HARQ processes based on configuration signals. By modifying parameters such as HARQ feedback timing, codebook size, and process activation status, the system can reduce latency impact while maintaining necessary reliability. The parameter changes allow the system to adapt to different service requirements in NTN environments.
2Productivity
If number of parallel HARQ processes is increased to maintain physical resource occupation time, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent applies partial HARQ operation by selectively enabling HARQ processes only when needed based on configuration signals. Instead of maintaining a fixed large number of parallel processes, the system activates only the necessary number of HARQ processes for current transmissions, reducing complexity while maintaining productivity when required.
Solution Approach 2:
The system dynamically adjusts the number and status of HARQ processes based on real-time configuration. This dynamic management allows the system to optimize between productivity and complexity by having fewer active processes most of the time while being able to scale up when necessary, rather than maintaining a complex fixed architecture.
3Measurement precision
If HARQ codebook size is increased to include all PDSCH receptions, then measurement precision of feedback is improved, but power control performance deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different PDSCH receptions in the codebook. Instead of uniformly including all receptions, the system selectively includes only those PDSCH receptions that have HARQ feedback enabled, creating a localized codebook that optimizes for power control while maintaining necessary feedback precision for active transmissions.
Solution Approach 2:
The codebook composition is dynamically adjusted based on configuration signals indicating which PDSCH receptions should be included. This dynamic codebook generation allows optimization of power control parameters by matching the codebook size and composition to the actual active transmissions, rather than using a fixed comprehensive codebook.
Data Source
AI summary
A method for a user equipment (UE) for performing a hybrid automatic repeat request (HARQ) codebook generation operation for downlink transmission(s) is disclosed. The method comprises receiving, from a base station, a dynamic scheduling configuration for HARQ feedback operation; receiving, from the base station, a scheduling signaling for a first physical downlink shared channel (PDSCH) reception with a first HARQ state feedback for the first PDSCH reception being disabled; and generating, for the HARQ feedback operation, a HARQ codebook excluding a first HARQ state for the first PDSCH reception.