NR-U Slot Format Determination via Target Time Window
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Solution Overview
Problem
The New Radio (NR) system based on unlicensed spectrum (NR-U) lacks a clear definition for determining slot formats, which is crucial for opportunistic communication due to the Listen Before Talk (LBT) principle, leading to inefficiencies in channel usage and data transmission.
Innovation Solution
A method and apparatus that dynamically determine slot formats in the NR-U system by using a target time window, which includes a Discovery Reference Signal (DRS) transmission window or a Channel Occupancy Time (COT) window, allowing terminal devices to determine the slot format based on these windows for effective channel utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Listen Before Talk (LBT) principle is applied for unlicensed spectrum communication, then channel collision is avoided and fair spectrum sharing is achieved, but channel utilization efficiency deteriorates due to opportunistic transmission constraints
Solution Approach 1:
The patent applies dynamics by making the slot format configurable and adaptable based on channel conditions and LBT outcomes. The network can dynamically adjust the slot format (downlink, uplink, or flexible symbol combinations) according to actual channel availability, transforming the rigid slot structure into a flexible one that responds to real-time spectrum conditions, thereby resolving the contradiction between reliable LBT-based access and efficient channel utilization
Solution Approach 2:
The patent changes the slot format parameters (downlink symbols, uplink symbols, flexible symbols) based on channel occupancy time and LBT results. By adjusting these parameters dynamically, the system can optimize channel utilization while maintaining LBT compliance, directly addressing the contradiction between reliability and productivity in unlicensed spectrum communication
2Device complexity
If a fixed slot format is used in NR-U system, then system complexity is reduced and implementation is simplified, but adaptability to varying channel conditions deteriorates
Solution Approach 1:
The patent transforms the static slot format into a dynamic one that can be adjusted according to channel occupancy time and LBT outcomes. The network device determines the slot format based on actual channel conditions, allowing the system to adapt to varying spectrum availability without requiring complex manual configuration, thus balancing adaptability with manageable system complexity
Solution Approach 2:
The system performs self-configuration of slot formats based on automatically detected channel conditions and LBT results. The network device autonomously determines the appropriate slot format without external intervention, reducing the complexity of manual configuration while maintaining high adaptability to changing channel conditions
3Measurement precision
If slot format determination is delayed until channel availability is confirmed, then transmission accuracy is improved by avoiding collisions, but transmission latency increases
Solution Approach 1:
The patent applies preliminary action by performing channel listening and determining slot formats in advance before actual data transmission. The network device executes LBT and configures slot formats proactively during idle periods or before channel occupancy begins, so that when transmission opportunities arise, the slot formats are already determined and ready, thereby reducing transmission latency while maintaining accurate channel detection
Solution Approach 2:
The system prepares slot format configurations in advance as a buffer for future transmission opportunities. By determining slot formats before actual channel occupancy, the system creates a time cushion that prevents transmission delays, ensuring that when LBT succeeds and channel becomes available, the slot format is already configured and transmission can begin immediately without additional determination delay
Data Source
AI summary
The implementations of the present disclosure relate to a method and apparatus for determining a slot format. The method includes: a terminal device determining a target time window on a first carrier, wherein the target time window includes at least one of the following: a discovery reference signal (DRS) transmission window and a channel occupancy time (COT) window, the DRS transmission window being used for transmitting a synchronization signal block (SSB); and the terminal device determining a slot format on the first carrier according to the target time window.