BWP Switch Failure Detection in 5G NR Uplink
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 5G NR systems face challenges in detecting and handling bandwidth part (BWP) switch failures, which can lead to uplink outages and call drops due to missed PDCCH transmissions and BWP mismatches, especially in multi-SIM modes, where UEs may tune away from the network, causing synchronization issues and prolonged recovery times.
Innovation Solution
A method is implemented in a network node to detect BWP switch failures by monitoring BLER, tune away events, and uplink grants within a detection window, allowing for prompt failure handling through RACH procedures or RLF recovery, ensuring quick resynchronization and minimizing data disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE performs BWP switch from first BWP to second BWP based on DCI, then the system can support flexible bandwidth adaptation, but BWP switch failure may occur leading to uplink outages and call drops
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors for downlink grants in the second BWP after switching. If no grant is received within a detection window, the UE determines the BWP switch failed and triggers recovery procedures. This feedback loop enables the system to detect and correct BWP switch failures, resolving the contradiction between bandwidth adaptation flexibility and uplink connection stability.
2Adaptability or versatility
If the UE tunes away from the network in multi-SIM mode, then the UE can handle multiple network subscriptions, but synchronization issues occur causing prolonged recovery times
Solution Approach 1:
The patent applies preliminary action by having the UE proactively monitor for downlink grants in the new BWP immediately after switching, before actual data transmission occurs. The UE sets a detection window and actively checks for grants during this period. This preliminary monitoring allows the UE to detect BWP switch failures early, especially important in multi-SIM mode where tune-away events can cause synchronization loss, thereby reducing recovery time.
3Device complexity
If the UE does not monitor for BWP switch failure, then the system operation is simple, but missed PDCCH transmissions occur leading to BWP mismatches
Solution Approach 1:
The patent implements self-service by having the UE autonomously monitor its own BWP switch status by checking for downlink grants in the target BWP. The UE independently determines whether the BWP switch was successful based on whether it receives expected grants, and autonomously triggers recovery procedures if failure is detected. This self-monitoring mechanism prevents PDCCH transmission loss and BWP mismatches without requiring complex external monitoring infrastructure.
Data Source
AI summary
A first network node (e.g., a UE) may receive, from a second BS network node (e.g., a base station), DCI. The first network node may perform, based on the DCI, a BWP switch from a first BWP to a second BWP. The first network node may perform, after the BWP switch, a BWP switch failure detection procedure that results in a first determination or a second determination. The first determination may be indicative that the BWP switch was successful and the second determination may be indicative that the BWP switch was not successful. To perform the BWP switch failure detection procedure, the first network node may determine whether one or more failure conditions are satisfied. The one or more failure conditions may include at least one of a BLER greater than a threshold, occurrence of one or more tune away events, or non-receipt of an uplink grant on the second BWP.