Cellular Handover Access Using TAU on Forbidden PLMN Nodes
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Solution Overview
Problem
Electronic devices experience communication degradation and temporary connection releases when attempting to handover to nodes listed in a forbidden public land mobile network (FPLMN) list due to temporary network errors, leading to repeated RRC connection releases and access rejections.
Innovation Solution
The electronic device includes a communication processor that identifies whether a target node for handover is on the FPLMN list based on system information and transmits a tracking area update (TAU) request signal, allowing access when an accept message is received, and adds the node to a list for measurement reporting failure if the accept message is not received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electronic device adds a node to the FPLMN list after access rejection, then access to that node is blocked, but this prevents successful handover when the rejection was due to temporary network error
Solution Approach 1:
The patent makes the FPLMN list dynamic by introducing a timer mechanism. When a node is added to the FPLMN list, a timer is started. If the timer expires before the node is successfully accessed, the node is removed from the FPLMN list. This dynamic adjustment allows the system to adapt to temporary network errors while maintaining access control for persistent forbidden networks.
Solution Approach 2:
The patent prepares for potential temporary network errors by implementing a timer-based protection mechanism before permanently blocking a node. The timer acts as a cushioning period that allows temporary access attempts, preventing premature addition to the FPLMN list due to transient errors, thus cushioning against false positives in access control.
2Reliability
If the electronic device repeatedly attempts handover to nodes on the FPLMN list, then access control is maintained, but communication quality degrades and connections are temporarily released
Solution Approach 1:
The system dynamically adjusts access control by implementing a timer mechanism that automatically removes nodes from the FPLMN list after a predetermined period. This prevents indefinite blocking of nodes that may have become accessible due to resolved temporary errors, thereby reducing communication degradation while maintaining access control reliability during the timer period.
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors handover attempts to nodes on the FPLMN list. When access is successfully established or the timer expires, the node is removed from the FPLMN list. This feedback loop prevents continuous failed access attempts that would degrade communication quality, while still enforcing access control during the monitoring period.
3Loss of energy
If the electronic device blocks access to nodes on the FPLMN list, then unnecessary signal transmissions are reduced, but this prevents successful handover when the block is due to temporary errors
Solution Approach 1:
The patent implements a dynamic FPLMN list management system with a timer mechanism. Nodes are temporarily blocked with an associated timer, and if the timer expires before successful access, the block is automatically removed. This dynamic approach reduces unnecessary signal transmissions during the timer period while allowing handover completion when temporary errors have resolved, optimizing the balance between energy loss and productivity.
Data Source
AI summary
An electronic device and method of operating an electronic device are provided. The electronic device includes a memory storing a forbidden public land mobile network (FPLMN) list including a node to which access of the electronic device is blocked, a communication circuit, and a communication processor configured to receive, through a first node, a handover command signal, search for a second node to which handover is to be performed, based on information included in the handover command signal, identify whether the second node is in the FPLMN list, based on system information broadcast by the second node and including information of multiple public land mobile networks (PLMNs), in case the second node is included in the FPLMN list, transmit a tracking area update (TAU) request signal to the second node, and connect to the second node according to reception of an accept message corresponding to the TAU request signal.