Multi-USIM Paging with Busy Token Signaling for Service Continuity
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Solution Overview
Problem
Existing methods for handling mobile terminated (MT) services in terminal devices with multiple USIMs cause unnecessary interruptions in currently-connected systems or waste resources in non-currently-connected systems due to the lack of flexible and secure mechanisms for indicating a busy state, and existing NAS messages require changes to carry busy indications.
Innovation Solution
A method where terminal devices with multiple USIMs generate and send a first message based on a busy token to inform the core network of their busy state without modifying existing NAS messages, using integrity protection and encryption to secure the busy indication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a terminal device with multiple USIMs responds to paging requests from non-currently-connected systems, then the device can maintain communication availability across multiple systems, but it may interrupt ongoing services in currently-connected systems
Solution Approach 1:
The terminal device performs preliminary assessment before responding to paging requests by checking whether it is currently busy in the currently-connected system. The device determines its availability status in advance and only responds to paging requests when not busy, preventing service interruption while maintaining communication availability across multiple systems
2Device complexity
If existing security mechanisms for busy indications are used, then implementation is simple, but they are vulnerable to attacks leading to resource wastage and security threats
Solution Approach 1:
The security mechanism is segmented into multiple independent components: busy token generation, busy token verification, and availability determination. Each component performs a specific security function, making the overall system more robust against attacks while maintaining manageable complexity through modular design
Solution Approach 2:
A busy token is introduced as an intermediary security element between the terminal device and the network. The token serves as a verified indicator of device availability status, protecting against attacks by requiring proper token verification before the network can determine device availability, thus enhancing security without significantly increasing complexity
3Measurement precision
If the terminal device sends detailed busy indication messages, then the core network can accurately determine availability, but message transmission overhead increases
Solution Approach 1:
The essential availability information is extracted from complex busy indication messages and condensed into a simple busy token. The token contains only the critical availability status verification needed by the core network, eliminating unnecessary message overhead while maintaining accurate availability determination through the verification process
Data Source
AI summary
A paging method includes: receiving, by a terminal device, a busy token forwarded by an access network device; receiving by a terminal device, a paging request from a non-currently-connected system forwarded by the access network device; generating, by a terminal device, a first message according to the busy token; and sending, by a terminal device, the first message to a core network device via the access network device.