Beam Indication in L1/2 Triggered Mobility for Fast Handover
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing beamforming and handover processes during mobility procedures, particularly in heterogeneous networks, leading to suboptimal performance and increased latency.
Innovation Solution
Implementing a layer 1/2 triggered mobility procedure that utilizes early time alignment and beam indication for seamless handovers, enabling efficient beam management and reducing the need for random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional handover procedures are used in heterogeneous networks, then network connectivity is maintained, but latency increases and mobility performance deteriorates
Solution Approach 1:
The patent applies preliminary action by performing time alignment and beam indication procedures before the actual handover occurs. The network configures and transmits timing advance values and beam information to the UE in advance, so that when handover is triggered, the UE can immediately apply these pre-configured parameters without waiting for measurement and configuration during the handover execution phase, thereby reducing handover latency while maintaining connectivity reliability
Solution Approach 2:
The patent segments the handover procedure into distinct phases: configuration phase (where time alignment and beam parameters are pre-configured), trigger phase (where handover is initiated based on measurements), and execution phase (where pre-configured parameters are applied). This segmentation allows the time-consuming configuration operations to occur separately before handover, reducing the critical path latency during actual mobility events while ensuring reliable parameter availability
2Reliability
If beam management is performed during handover, then beamforming performance is optimized, but procedure complexity and processing overhead increase
Solution Approach 1:
The patent applies preliminary action by performing beam management operations in advance of the handover event. The network configures beam parameters, performs beam measurements, and determines optimal beam directions before handover is triggered. This allows beamforming optimization to be completed beforehand, so that during actual handover, the UE simply applies pre-determined beam parameters without complex real-time beam management, thereby maintaining beamforming performance while reducing procedure complexity
Solution Approach 2:
The patent enables self-service by having the UE autonomously measure reference signals, evaluate beam qualities, and report measurements to the network without extensive network control during the measurement and evaluation phase. The network then uses these self-generated measurements to make beam selection decisions, reducing the signaling overhead and processing complexity required for coordinated beam management during handover
3Loss of time
If random access procedures are performed during handover, then uplink synchronization is achieved, but handover time and service interruption increase
Solution Approach 1:
The patent applies preliminary action by having the network configure and provide timing advance values to the UE before handover execution. The UE uses these pre-configured timing advance parameters to achieve uplink synchronization with the target cell without needing to perform a full random access procedure, thereby reducing handover time while maintaining uplink synchronization reliability
Solution Approach 2:
The patent extracts the essential synchronization function from the complete random access procedure. Instead of performing the entire random access sequence (preamble transmission, random access response, contention resolution), the patent isolates and applies only the timing synchronization aspect using pre-configured parameters, removing the unnecessary overhead and delay of the full random access procedure while maintaining the critical uplink synchronization function
Data Source
AI summary
A method may include receiving, by a wireless device, one or more radio resource control (RRC) messages. The messages may include first parameters of a first list of transmission configuration indicator (TCI) states of a first cell for LTM, and second parameters of a second list of TCI states of the cell. The method may also include receiving an LTM cell switch command MAC CE indicating an LTM cell switch. The command comprises a first field indicating the first cell as a target cell, and a second field comprising a TCI state ID indicating activation of a first TCI state of the first list for the first cell. The method may further include communicating with a base station and via the first cell, signals or channels using the first TCI state indicated in the MAC CE. The first TCI state is used in a time duration after receiving the one or more RRC messages and before applying a second TCI state, indicated by an activation command, from the second list for the first cell.