Uplink Channel Access Priority Class Determination in 5G NR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In 3GPP 5G new radio (NR) systems, base stations (BSs) face challenges in accurately determining the Channel Access Priority Class (CAPC) value for uplink data transmission on unlicensed spectrum, leading to misunderstandings and unnecessary complexity due to lack of knowledge about buffer status and traffic Quality of Service (QoS) of user equipment (UE) data, and incorrect channel access procedures.
Innovation Solution
The proposed solution involves a method where User Equipment (UE) determines the CAPC value based on uplink traffic data, with base stations (BSs) indicating the CAPC value used for initiating channel occupancy, and UE performing appropriate channel access procedures such as LBT Cat. 2 or LBT Cat. 4, depending on the scheduled PUSCH transmission being inside or outside of the BS-initiated Channel Occupancy Time (COT), thereby simplifying the signaling and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station determines the CAPC value independently, then the UE can perform channel access procedures, but the BS lacks knowledge of UE buffer status and traffic QoS leading to incorrect channel access
Solution Approach 1:
The patent introduces an intermediary signaling mechanism where the UE reports its buffer status and traffic QoS information to the BS, and the BS uses this information to determine the appropriate CAPC value. This intermediary information exchange resolves the information asymmetry between BS and UE, enabling accurate CAPC determination while maintaining BS control over channel access procedures.
2Reliability
If the UE determines the CAPC value based on buffer status, then accurate channel access can be achieved, but increased signaling complexity is required
Solution Approach 1:
The patent makes the buffer status report signaling multi-functional by having it serve both as standard uplink data transmission and as the basis for CAPC determination. The existing uplink shared channel resources are used to convey both data and buffer status information, eliminating the need for separate dedicated signaling and reducing overall signaling complexity.
Solution Approach 2:
The UE autonomously determines the CAPC value based on its own buffer status and traffic QoS information without requiring explicit CAPC assignment from the BS. This self-service approach reduces signaling overhead while maintaining accurate channel access, as the UE uses its local knowledge to make appropriate channel access decisions.
3Reliability
If LBT Cat. 4 with random backoff is used, then fair channel access is achieved, but transmission delay increases
Solution Approach 1:
The patent dynamically selects the LBT category based on the determined CAPC value and current channel conditions. When the CAPC indicates low priority or congested conditions, LBT Cat. 4 with random backoff is used for fairness. When CAPC indicates high priority or favorable conditions, LBT Cat. 2 or Cat. 1 is used to reduce delay. This dynamic adaptation resolves the contradiction between fairness and delay.
Solution Approach 2:
The patent changes the LBT parameters (category selection, backoff window size, contention resolution mechanism) based on the CAPC value determined from buffer status and QoS requirements. Different CAPC values map to different LBT parameter sets, allowing the system to adjust channel access behavior to match traffic priorities and reduce unnecessary delays for time-sensitive data.
Data Source
AI summary
The present application relates to a method and apparatus for uplink data transmission or reception. One embodiment of the subject application provides a method for uplink data transmission performed by a User Equipment (UE), comprising: receiving, from a base station (BS), a first signalling indicating a first channel access priority class value, wherein the first channel access priority class value is used by the BS for initiating a channel occupancy; receiving, from the BS, a second signalling scheduling a Physical Uplink Shared Channel (PUSCH) for transmitting uplink data; performing a channel access procedure; and transmitting, to the BS, the uplink data on the PUSCH in response to the channel access procedure being successful.