RLC Length Indicator PLMN ID Signaling
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Solution Overview
Problem
Current communication systems lack a mechanism for a mobile station to indicate its preferred Public Land Mobile Network (PLMN) ID to the Radio Access Network (RAN) when accessing the Packet Switched domain, leading to increased signaling load and potential hijacking risks.
Innovation Solution
A mobile station includes its chosen PLMN ID in a Radio Link Control (RLC) data block using a reserved value in the Length Indicator field, allowing the RAN to identify and extract the ID without modifying existing NAS messages, thereby conveying the PLMN selection to the RAN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new RLC/MAC message is introduced to send PLMN ID from MS to RAN, then the PLMN ID can be conveyed to the RAN, but the device complexity and signaling load increase
Solution Approach 1:
The invention reuses the existing RLC data block structure and its length indicator field for a new purpose (carrying PLMN ID), rather than creating a dedicated new message type. This allows the existing RLC mechanism to serve multiple functions: both its original data transmission role and the new PLMN ID indication role, thereby avoiding increased device complexity while maintaining reliability
2Reliability
If PLMN ID is included in NAS messages, then the PLMN ID can be conveyed to the CN, but the RAN cannot reliably identify the preferred PLMN due to message transparency and random selection
Solution Approach 1:
The invention extracts the PLMN ID indication from the transparent NAS message tunneling approach and places it directly in the RLC data block at the RAN level. This extraction allows the RAN to directly access and reliably identify the PLMN ID without having to randomly select or decode through transparent NAS messages, thereby preventing information loss and ensuring accurate PLMN identification
3Loss of energy
If PLMN ID is transmitted via existing RLC data blocks without modification, then the air interface load is not increased, but there is no mechanism to indicate the presence of PLMN ID in the data block
Solution Approach 1:
The invention changes the parameter values in the existing RLC data block structure by using reserved or pre-defined values in the length indicator field to signal the presence of PLMN ID. This parameter change approach allows the system to convey additional information (PLMN ID presence) without modifying the fundamental RLC data block structure or increasing air interface load, as the same field is reused with different value meanings
Data Source
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AI summary
A mobile station (110) for use in a Radio Access Network, RAN (102), connected to a core network (101 ) in which there is one or more Public Land Mobile Networks, PLMNs (103, 104, 105). The mobile station (11 0) is arranged to select one of said PLMNs (103, 104, 105), and is arranged to communicate with its RAN (102) by means of Radio Link Control, RLC, data blocks. The mobile station is arranged to include the identity, I D, of its selected PLMN in an RLC data block, and to inform the RAN (102) of the presence of the ID of the chosen PLMN in the RLC data block by means of including a reserved or pre-defined value in the length indication field of the RLC data block.