BWP Switching for Seamless MBS Reception in NR
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Solution Overview
Problem
In wireless communication systems, particularly in New Radio (NR) technology, there is a challenge in efficiently managing bandwidth parts (BWP) and common frequency resources during multicast/broadcast services, leading to disruptions in ongoing receptions when switching between unicast and multicast/broadcast bandwidths.
Innovation Solution
A method where a user equipment (UE) receives a physical downlink control channel (PDCCH) carrying downlink control information (DCI) for BWP switching, activates a new BWP, and switches to a new common frequency resource (CFR) associated with the new BWP, allowing seamless continuation of multicast/broadcast service data transmission by transmitting a negative acknowledgement (NACK) or acknowledgement (ACK) based on the active BWP before or after activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE switches from the first BWP to the second BWP during multicast/broadcast service reception, then the UE can access different frequency resources for unicast communication, but the ongoing multicast/broadcast service reception is disrupted
Solution Approach 1:
The patent segments the bandwidth into multiple BWPs (first BWP for multicast/broadcast, second BWP for unicast) and segments the frequency resources into first CFR and second CFR. By maintaining separate CFUs for each BWP type, the system allows independent operation of multicast/broadcast services and unicast communications, enabling BWP switching without disrupting ongoing services.
Solution Approach 2:
The patent performs preliminary configuration of multiple CFUs (first CFR associated with first BWP, second CFR associated with second BWP) before switching is needed. When BWP switching is indicated via DCI, the UE is already prepared with the second CFR configuration, allowing seamless switching without service disruption. The acknowledgment mechanism is also prepared in advance to handle retransmissions.
2Reliability
If the UE maintains the first CFR active during BWP switching to the second BWP, then multicast/broadcast service reception continues, but frequency resource allocation becomes inefficient
Solution Approach 1:
The patent implements dynamic CFR management where the active CFR changes based on the active BWP. When the UE switches from first BWP to second BWP, it dynamically switches from first CFR to second CFR. This dynamic adaptation ensures that frequency resources are efficiently allocated to the currently active service type, preventing waste while maintaining service continuity.
Solution Approach 2:
The patent changes the CFR parameter (frequency resource allocation) based on the active BWP state. When BWP switching is triggered, the UE changes from using first CFR to second CFR, optimizing frequency resource utilization for the new service type while maintaining continuous service reception through proper acknowledgment and retransmission handling.
3Reliability
If the UE transmits NACK for first MBS data before BWP switching, then retransmission can be requested, but the timing of retransmission reception becomes complex with BWP change
Solution Approach 1:
The patent uses the DCI (Downlink Control Information) as an intermediary to coordinate the complex interaction between NACK transmission, BWP switching, and retransmission scheduling. The DCI not only triggers BWP switching but also schedules the retransmission of MBS data in the new CFR, providing a unified mechanism that simplifies the overall process despite the multiple involved operations.
Solution Approach 2:
The DCI serves multiple functions: it triggers BWP switching, schedules retransmissions, and indicates CFR changes. This multi-functionality reduces the need for separate signaling mechanisms and simplifies the overall control structure, making the system more manageable despite the complexity of coordinating retransmissions with BWP switching.
Data Source
AI summary
According to an embodiment of the present invention a user equipment (UE) may receive, in a first common frequency resource (CFR) associated with a first bandwidth part (BWP) which is an active BWP of the UE, first multicast/broadcast service (MBS) data; receive, in the first BWP, a physical downlink control channel (PDCCH) carrying downlink control information (DCI) including information regarding BWP switching; activate a second BWP based on the DCI; and receive second MBS data, wherein, based on that the active BWP has been changed from the first BWP to the second BWP and a second CFR different from the first CFR is associated with the second BWP, the UE activates the second CFR and receives the second MBS data in the second CFR.