MAC CE Mobility Switching With Preconfigured PDCP Security
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Solution Overview
Problem
Existing wireless communication systems face high latency and interruption times during cell handover due to L3 measurements and signaling, which are not suitable for the demanding requirements of 5G systems.
Innovation Solution
Implementing L1/L2 Triggered Mobility (LTM) by using MAC Control Elements (CE) for UE mobility management, enabling lower layer triggered cell switching through early synchronization and configuration of PDCP entities with encryption keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3 measurements and RRC signaling are used for serving cell change, then mobility management is achieved, but latency and interruption time increase
Solution Approach 1:
The patent performs PDCP entity configuration and key derivation in advance before handover is triggered. The UE receives and stores PDCP configuration parameters (encryption keys, initialization vectors, sequence numbers) from the source cell, preparing security context beforehand. This preliminary configuration enables faster execution during actual handover, reducing latency and interruption time while maintaining reliable mobility management.
2Reliability
If complete L2 and L1 resets are performed during serving cell change, then security is maintained, but overhead and interruption time increase
Solution Approach 1:
The patent extracts the essential security functions from the complete L2 reset procedure. Instead of performing full L2 reset, the invention selectively maintains PDCP entity configurations and security contexts that are needed for continuity. By taking out only the necessary security maintenance operations and eliminating unnecessary reset steps, the patent reduces overhead while preserving security requirements.
3Reliability
If RRC signaling is used for reconfiguration, then mobility control is achieved, but the number of signaling messages and processing time increase
Solution Approach 1:
The patent introduces MAC Control Elements (MAC CEs) as an intermediary mechanism between RRC layer and physical layer for mobility control. MAC CEs provide a faster signaling path compared to traditional RRC messages, enabling quicker transmission of handover commands and configuration updates. This intermediary approach maintains mobility control reliability while significantly reducing signaling processing time and message overhead.
Data Source
AI summary
A method to enable efficient data transfer for cell switch in conjunction with LTM operation is provided. The method of the terminal includes receiving from a specific Medium Access Control (MAC) Control Element (CE), deriving a second key-derivation-key based on a specific first key-derivation-key, wherein the specific first key-derivation-key is determined based on the specific integer in the MAC CE, deriving a first encryption-key based on the second key-derivation-key, configuring a specific set of Packet Data Convergence Protocol (PDCP) entities with the first encryption-key and reestablishing the specific set of PDCP entities.