Flexible Symbols in NR-U COT Structures
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Solution Overview
Problem
The challenge in wireless communication systems, particularly in New Radio (NR) systems operating on unlicensed spectrum, is to efficiently manage slot format indicators (SFIs) and channel occupancy time (COT) structures to ensure fair coexistence with other technologies and comply with regulatory restrictions.
Innovation Solution
The proposed solution involves a base station that generates and transmits a slot format indicator (SFI) associated with a channel occupancy time (COT) structure, indicating whether slots are for downlink (DL), uplink (UL), or flexible symbols. Flexible symbols create gaps in the COT structure if not overridden for DL or UL transmissions, allowing the base station to dynamically manage the COT duration within regulatory limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station continuously transmits DL symbols without gaps, then the channel occupancy time is maximized and spectrum efficiency is improved, but interference to other systems operating in the same unlicensed spectrum increases and regulatory compliance becomes difficult
Solution Approach 1:
The COT structure is segmented into multiple slots with flexible symbols that can create gaps between DL transmissions. These gaps allow the system to share the unlicensed spectrum fairly with other technologies while maintaining overall high efficiency through multiple DL/UL switching points within the shared COT.
2Adaptability or versatility
If gaps are inserted in the COT structure to ensure fair coexistence, then interference to other systems is reduced and regulatory compliance is improved, but the channel occupancy time duration decreases and spectrum efficiency is reduced
Solution Approach 1:
The flexible symbols in the COT structure are dynamically configurable to be overridden as DL or UL transmissions based on traffic requirements. This dynamic adjustment allows the system to optimize the balance between coexistence (gaps) and productivity (continuous transmission) in real-time according to network conditions.
3Adaptability or versatility
If multiple DL/UL switching points are implemented within a shared COT, then flexibility in resource allocation is improved and power consumption is optimized, but the complexity of managing slot formats increases
Solution Approach 1:
The flexible symbols serve multiple functions: they can create gaps for fair coexistence, be overridden as DL transmissions for high productivity, or be configured as UL transmissions for bidirectional communication. This multi-functionality simplifies the overall structure by using a single flexible symbol mechanism to handle diverse resource allocation requirements.
Data Source
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AI summary
There is provided a user equipment, UE, comprising: radio front end circuitry; and processor circuitry coupled to the radio front end circuitry. The processor circuitry is configured to: receive, using the radio front end circuitry and from a base station, a slot format indicator, SFI, associated with a channel occupancy time, COT, structure, wherein the SFI indicates whether one or more slots associated with the COT structure are to be used for downlink, DL, symbols, uplink, UL, symbols, or flexible symbols, wherein the flexible symbols form one or more gaps in the COT structure in response to the flexible symbols not being overridden as a DL transmission or a UL transmission, wherein a duration of the one or more gaps is counted toward a duration of the COT structure in response to the duration of the one or more gaps being less than or equal to a threshold and the duration of the one or more gaps is not counted toward a duration of the COT structure in response to the duration of the one or more gaps being greater than the threshold; and use the SFI for transmitting of the UL symbols or receiving of the DL symbols between the base station and UE.