Joint BWP Switching for Cross-Link Interference Control
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Solution Overview
Problem
Cross-link interference (CLI) occurs when a first UE transmits to a base station while a second UE receives from the base station, especially if their frequency bands are too close, necessitating mechanisms to manage this interference.
Innovation Solution
A base station assigns bandwidth parts (BWPs) for victim and aggressor UEs with minimum guard bands, signals these assignments via downlink messaging, and directs UEs to switch BWPs using group common DCI, with a common reference SCS for delay determination, and manages BWP switches to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bandwidth parts are assigned to victim UEs and aggressor UEs with minimum guard bands to reduce cross-link interference, then interference management is improved, but frequency resource utilization deteriorates
Solution Approach 1:
The patent implements dynamic BWP switching where the base station can reassign bandwidth parts to victim and aggressor UEs based on real-time interference conditions. The minimum guard band requirements are not fixed but adapt through joint BWP switching, allowing the system to optimize the balance between interference protection and resource utilization dynamically rather than statically allocating frequencies with fixed guard bands.
Solution Approach 2:
The patent changes the frequency allocation parameters by switching BWPs for groups of UEs jointly. By modifying the BWP assignments and guard band configurations through base station control, the system can adjust the frequency separation between victim and aggressor UEs, thereby optimizing the trade-off between interference reduction and resource efficiency.
2Productivity
If a group of UEs is directed to switch bandwidth parts using group common DCI, then switching coordination is improved, but control signaling overhead increases
Solution Approach 1:
The patent merges the control signaling for multiple UEs into a single group common DCI message. Instead of sending individual BWP switching commands to each UE, the base station combines the switching instructions for a group of UEs (including both victim and aggressor UEs) into one unified control message, reducing the total number of control signals while maintaining coordinated switching.
Solution Approach 2:
The group common DCI serves multiple functions simultaneously: it directs BWP switching for multiple UEs, coordinates interference management, and maintains synchronization across the group. This multi-functional approach reduces overall signaling overhead compared to separate dedicated control messages for each UE.
3Reliability
If joint bandwidth part switching is implemented for victim and aggressor UEs, then cross-link interference reduction is improved, but system complexity increases
Solution Approach 1:
The base station performs preliminary assessment of interference conditions by identifying victim and aggressor UEs before executing joint BWP switching. By pre-determining which UEs require coordinated switching and calculating appropriate guard band requirements in advance, the system reduces the complexity of real-time processing while ensuring effective interference avoidance.
Solution Approach 2:
The base station acts as an intermediary that coordinates BWP switching between victim and aggressor UEs. It receives minimum guard band requirements from victim UEs, determines appropriate BWP assignments, and manages the switching process centrally, thereby simplifying the overall system architecture compared to distributed interference management approaches.
Data Source
AI summary
A base station may transmit a message to a group of user equipments (UEs), directing the UEs to change their respective bandwidth parts (BWPs). For each of the UEs of the group, the message may include a corresponding new BWP. In response to receiving the message, each UE of the group may switch to the corresponding new bandwidth part. The message may be transmitted as part of a group common DCI message. The UE may signal its required minimum guard band size to the base station. Alternatively, the UE may respond to the message with an acknowledgement message. The base station may configure a virtual common downlink BWP for the group of UEs. The UEs drop transmission/reception repetitions that occurs during its BWP switch delay period.