SSB Beam Switching for Soft PCI Change Without Resynchronization
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently transitioning between physical cell identifiers (PCIs) without causing collisions and maintaining timing synchronization and channel estimation, particularly in heterogeneous networks.
Innovation Solution
A network node optimizes transmission beams by transitioning from one PCI to another while continuing to transmit signals on both PCIs during a transition period, then ceasing transmission on the original PCI, guided by configuration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the physical cell identifier (PCI) is changed to resolve PCI confusion, then PCI confusion is eliminated, but uplink synchronization is lost and random access procedure is required
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple SSB beams with different PCI values before the handover occurs. The target gNB prepares alternative SSB beams with different PCIs in advance, so when PCI confusion is detected, the UE can immediately switch to a pre-prepared alternative beam without needing to perform random access procedure, thus maintaining uplink synchronization while resolving PCI confusion.
Solution Approach 2:
The patent implements dynamics by making the SSB beam configuration dynamic and adjustable. Instead of using a fixed PCI for the target cell, the system dynamically selects and switches between multiple SSB beams with different PCI values based on real-time conditions. This dynamic beam switching capability allows the system to adapt to PCI confusion situations by selecting an alternative beam that does not cause confusion, thereby resolving the contradiction between eliminating PCI confusion and maintaining uplink synchronization.
2Reliability
If the SSB beam is switched to resolve PCI confusion, then PCI confusion is eliminated, but beam switching complexity increases
Solution Approach 1:
The patent reduces beam switching complexity through preliminary action by having the target gNB pre-configure and signal multiple alternative SSB beam identifiers to the source gNB before handover. The source gNB then provides these pre-signalized beam identifiers to the UE in the handover command. This approach simplifies the switching process because the UE only needs to select from a pre-approved list of alternative beams rather than performing complex real-time beam selection, thereby eliminating PCI confusion while keeping device complexity manageable.
3Reliability
If random access procedure is performed after PCI change, then uplink synchronization is restored, but handover time increases
Solution Approach 1:
The patent applies preliminary action by maintaining uplink synchronization continuously throughout the handover process. The target gNB pre-configures alternative SSB beams with different PCIs and ensures that uplink synchronization resources are already allocated and ready. When PCI confusion is detected, the UE can switch to an alternative pre-synchronized beam immediately without needing to perform the time-consuming random access procedure, thus restoring and maintaining uplink synchronization while minimizing handover time.
Solution Approach 2:
The patent implements continuity of useful action by maintaining continuous uplink synchronization during the handover process. Instead of breaking synchronization and requiring re-establishment through random access, the system continuously maintains synchronization by having the UE switch between pre-configured SSB beams. This continuous synchronization approach eliminates the time loss associated with random access procedures while ensuring reliable uplink connection throughout the handover.
Data Source
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AI summary
Aspects of disclosure relate to a network node for changing a physical cell identifier (PCI). The network node transmits a first signal based on a first PCI during a first synchronization signal block (SSB) occasion, transmits a second signal based on the first PCI during a second SSB occasion, and transitions from the first PCI to a second PCI. During a transition period, the network node transmits the first signal based on the second PCI during the first SSB occasion, and continues to transmit the second signal based on the first PCI during the second SSB occasion. After an end of the transition period, the network node continues to transmit the first signal based on the second PCI during the first SSB occasion, and ceases transmission of the second signal based on the first PCI during the second SSB occasion. Other aspects and features are also claimed and described.