NR-U PUSCH Time-Domain Allocation Under LBT Uncertainty
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Solution Overview
Problem
The challenge in 5G NR-U (New Radio-Unlicensed) spectrum access is how to effectively allocate time domain resources using slots and mini-slots to manage interference and improve uplink transmission success rates and spectrum efficiency.
Innovation Solution
A method for allocating time domain resources is provided, where a base station transmits DCI signaling to indicate the use of slots and/or mini-slots for PUSCH transmission, specifying starting and ending symbols, redundancy versions, and LBT monitoring positions to optimize resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LBT mechanism is used to monitor PUSCH channel idle status, then interference from neighboring base stations is avoided, but uplink transmission success rate is reduced due to channel access uncertainty
Solution Approach 1:
The time domain resource is segmented into multiple slots and mini-slots, allowing the terminal to perform PUSCH transmission in multiple segmented time units. This segmentation enables the system to accommodate LBT uncertainties by providing multiple transmission opportunities within the same scheduled resource, thereby improving transmission success rate while maintaining interference avoidance through LBT monitoring.
2Productivity
If multiple subframes are scheduled with LAA uplink scheduling mode, then spectrum efficiency is improved, but configuration complexity of redundancy version increases
Solution Approach 1:
The redundancy version configuration is made dynamic by associating it with slot indicators rather than fixed subframe configurations. The DCI signaling dynamically indicates the slot where PUSCH transmission should start and the corresponding redundancy version to use, allowing flexible adaptation to channel conditions and LBT outcomes while maintaining manageable configuration complexity through dynamic signaling.
3Device complexity
If time domain resources are allocated using only slots, then resource allocation is simple, but transmission flexibility is reduced
Solution Approach 1:
The time domain resource structure is segmented into slots and mini-slots, where a slot can contain one or more mini-slots. This hierarchical segmentation provides transmission flexibility by allowing the system to schedule PUSCH at different granularities (full slot or partial mini-slot) while maintaining relatively simple resource allocation through the parent slot structure. The DCI signaling can indicate either slot-based or mini-slot-based transmission starts.
Data Source
AI summary
A base station transmits downlink control information, DCI, signaling. The DCI signaling indicates a time domain resource to be used to perform physical uplink shared channel, PUSCH, by a terminal. The time domain resource includes at least one slot, at least one mini-slot, or both the at least one slot and at least one mini-slot.