LTE Paging Handling for Circuit Switched Fallback in Connected Mode
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Solution Overview
Problem
Mobile wireless devices can miss incoming voice connections due to misaligned radio resource control (RRC) connection states with LTE wireless networks, leading to failed circuit switched fallback (CSFB) procedures when transitioning from packet switched to circuit switched connections.
Innovation Solution
The mobile wireless device implements a method to respond to paging messages by disconnecting from an LTE network and establishing a connection to a legacy network for CS voice connections, even when in an RRC connected state, by identifying unique information elements and releasing RRC connections to redirect to a non-LTE network for CS voice establishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile wireless device follows standardized CSFB procedures assuming RRC idle state, then the network can page the device correctly, but the device may miss incoming voice connections if it is actually in RRC connected state
Solution Approach 1:
The mobile device monitors paging messages from the network and detects discrepancies between its internal RRC state and the network's expected state. When a paging message is received while in RRC connected state, the device recognizes this as a state misalignment feedback signal and automatically transitions to RRC idle state to resolve the contradiction.
Solution Approach 2:
The device dynamically adjusts its RRC connection state based on received paging messages. Instead of maintaining a fixed state assumption, the device transitions from static RRC connected state to RRC idle state when paging is detected, allowing adaptive response to network expectations and ensuring reliable voice connection establishment.
2Productivity
If the mobile wireless device maintains RRC connected state for data connections, then data transmission efficiency is improved, but the device cannot properly respond to CSFB paging messages
Solution Approach 1:
The device periodically checks for paging messages during data connections and uses this periodic monitoring to detect when state alignment is needed. The periodic paging message reception serves as a trigger to transition from RRC connected to RRC idle state, allowing the device to maintain high data efficiency while periodically ensuring voice connection readiness.
Solution Approach 2:
The device performs a preliminary state transition to RRC idle when paging is detected, before attempting to establish voice connections. This preliminary action ensures the device is in the correct state to respond to CSFB procedures, preventing future connection failures and avoiding the need for more complex recovery procedures later.
3Stability of the object's composition
If the mobile wireless device ignores paging messages in RRC connected state, then data connection stability is maintained, but incoming voice connections are missed
Solution Approach 1:
The paging message acts as an intermediary signal that mediates between the device's desire to maintain stable RRC connected state and the network's need to establish voice connections. Upon receiving this intermediary signal, the device temporarily transitions to RRC idle state, allowing voice connections to be established while minimizing disruption to overall connection stability.
Solution Approach 2:
The device changes its RRC connection state parameter from connected to idle when paging messages are detected. This parameter change allows the device to respond appropriately to CSFB procedures while maintaining overall connection stability through controlled, conditional state transitions rather than continuous instability.
Data Source
AI summary
Methods, apparatuses and computer readable media are described that analyze and communicate signaling messages between a mobile wireless device and a wireless access network to realize a circuit switched fallback (CSFB) procedure when the mobile wireless device is initially in a radio resource control connected mode with the wireless network. A set of information elements of a paging message is analyzed, and based on contents of the set of information elements and an internal state of the mobile wireless device, connections between the mobile wireless device and first and second wireless access networks are changed to realize the CSFB procedure.