Dynamic HARQ Field Configuration for NTN Reliability
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G NR, face challenges in managing Hybrid Automatic Repeat Request (HARQ) processes and Adaptive Modulation and Coding (AMC) due to long round trip times in Non-Terrestrial Networks (NTN) scenarios, leading to inefficiencies in data transmission and reliability.
Innovation Solution
The method involves configuring specific parameters in the RRC configuration for UE to manage HARQ processes and AMC, including disabling HARQ feedback, adjusting the number of bits in HARQ fields, and using new BLER and MCS tables tailored for NTN scenarios, as well as enabling polarization mismatch compensation to enhance CQI reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of bits in HARQ process ID field is increased to support more HARQ processes in NTN, then the reliability of data transmission is improved, but the device complexity and signaling overhead increase
Solution Approach 1:
The patent implements dynamic configuration of the HARQ process ID field bit width through RRC parameters. The network can adaptively adjust the number of bits based on the specific NTN scenario requirements, allowing the system to optimize between reliability and complexity dynamically rather than using a fixed configuration
Solution Approach 2:
The patent introduces configurable parameters (nrofHARQ-ProcessesForPDSCH, harq-ProcessNumberFieldWidth) that allow changing the HARQ field characteristics. By modifying these parameters, the system can support different numbers of HARQ processes (e.g., 16, 32, 64, or more) without changing the fundamental protocol structure, thus resolving the contradiction between reliability needs and system complexity
2Speed
If HARQ feedback is disabled to reduce latency in NTN scenarios, then the transmission speed is improved, but the reliability of data transmission deteriorates
Solution Approach 1:
The patent enables dynamic control of HARQ feedback through the harq-FeedbackLessRetransmission parameter. The network can switch between feedback-based and feedback-less retransmission modes depending on the specific transmission conditions, allowing optimization of both speed and reliability for different scenarios rather than using a fixed approach
Solution Approach 2:
The patent segments the retransmission mechanism into two distinct paths: traditional HARQ feedback-based retransmission and feedback-less retransmission. This segmentation allows the system to select the appropriate path based on latency requirements and reliability needs, resolving the contradiction between speed and reliability
3Measurement precision
If polarization mismatch compensation is enabled to improve CQI reporting accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies polarization mismatch compensation specifically to CQI measurements when configured through the circularPolarization parameter. Instead of applying complex processing universally, the system selectively enables compensation only where needed (in NTN scenarios with circular polarization), thus improving measurement precision without unnecessarily increasing complexity in all cases
Data Source
AI summary
A user equipment (UE) and a method for wireless communication are provided. The method includes: receiving a radio resource control (RRC) configuration from a base station (BS); determining whether a first parameter is configured in the RRC configuration; receiving first downlink control information (DCI) from the BS, the first DCI including a first field indicating a first Hybrid Automatic Repeat Request (HARD) process identifier (ID); determining that a number of bits in the first field is a default number in a case that the first parameter is not configured in the RRC configuration; and determining that the number of bits in the first field is a specific number greater than the default number in a case that the first parameter is configured in the RRC configuration.