Uplink Downlink COT Sharing in NR-U
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Solution Overview
Problem
Wireless communication systems face challenges in efficiently sharing channel occupancy time (COT) in frequency spectra shared by multiple network operating entities, particularly in unlicensed or shared spectrum environments, leading to potential collisions and inefficiencies in data transmission.
Innovation Solution
A method where a base station (BS) transmits a UL scheduling grant to a user equipment (UE) for a UL schedule outside of its COT, allowing the UE to perform a CAT4 LBT to acquire a COT for UL transmission, and includes COT sharing information in the UL communication signal to enable the BS to share the UE's COT for DL communications, optimizing resource utilization and reducing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BS schedules UL transmission outside its COT, then the BS can maintain its COT for DL communications, but the UE must perform CAT4 LBT which increases transmission latency
Solution Approach 1:
The patent implements dynamic COT sharing where the BS can flexibly schedule UL transmissions either within or outside its COT based on real-time channel conditions and traffic requirements. The system dynamically adjusts scheduling decisions to optimize both latency and reliability trade-offs
Solution Approach 2:
The patent changes the LBT category parameter dynamically - using CAT2 LBT when UL transmission is scheduled within BS COT (reducing latency) and CAT4 LBT when scheduled outside COT (ensuring reliability). This parameter adaptation resolves the contradiction between speed and reliability
2Reliability
If the UE performs CAT4 LBT to acquire COT for UL transmission, then the UE can ensure clear channel access, but the COT duration is extended reducing spectrum sharing efficiency
Solution Approach 1:
The patent applies partial LBT action by using CAT2 LBT (simplified version) when the UE transmits within BS COT, avoiding the full CAT4 LBT procedure. This partial action maintains sufficient reliability while significantly reducing the COT duration and improving spectrum sharing efficiency
Solution Approach 2:
The patent segments the COT into different portions - a first portion for UL transmission and a second portion for DL transmission. This segmentation allows the UE to use a shorter COT for UL while the BS can utilize the remaining time for DL communications, improving overall spectrum efficiency
3Productivity
If the BS schedules DL transmission within the UE's COT, then the BS can utilize the shared COT for DL communications, but the BS must perform CAT2 LBT which may cause collisions
Solution Approach 1:
The patent implements feedback mechanisms where the BS receives UL transmissions from the UE and uses this feedback to determine appropriate DL scheduling decisions. The BS adjusts its DL transmission timing and LBT requirements based on the UL transmission characteristics and channel conditions, resolving collisions dynamically
Solution Approach 2:
The patent applies preliminary action by having the UE include COT sharing information in its UL transmission signal, which provides advance notice to the BS about the COT duration and characteristics. This allows the BS to perform preliminary scheduling calculations and avoid collisions before DL transmission occurs
Data Source
AI summary
Wireless communications systems and methods related to sharing a channel occupancy time (COT) associated with a scheduled UL transmission in a frequency spectrum shared by multiple network operating entities are provided. A first wireless communication device communicates, with a second wireless communication device, a first uplink (UL) scheduling grant. The first wireless communication device communicates, with second wireless communication device, a first UL communication signal based on the first UL scheduling grant during a first COT, the first COT based on an extended clear channel assessment (eCCA) associated with the first UL communication signal. The first wireless communication device communicates, with the second wireless communication device, a downlink (DL) communication signal during the first COT based on COT sharing information associated with the first COT.