Wireless Device IMS Transfer Address Selection for Handover
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Solution Overview
Problem
Wireless communication devices (WCDs) configured to support both single radio voice call continuity (SRVCC) and dual radio voice call continuity (DRVCC) face handover failures due to receiving different IMS transfer-addresses from the IMS when transitioning between RANs, leading to incorrect routing of signaling messages.
Innovation Solution
A method and system where the WCD maintains and selects between two IMS transfer-addresses, one for single-radio transitions and another for dual-radio transitions, ensuring the appropriate address is used for seamless handover during RAN changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the WCD receives different IMS transfer-addresses from the IMS when transitioning between RANs for SRVCC and DRVCC, then the WCD can support both single-radio and dual-radio voice call continuity, but handover failures occur due to incorrect routing of signaling messages
Solution Approach 1:
The patent segments the single IMS transfer-address into two distinct addresses: one for SRVCC (single-radio voice call continuity) and one for DRVCC (dual-radio voice call continuity). This segmentation allows the system to maintain separate routing paths for different handover types, eliminating the conflict that arises when a single address must serve multiple purposes. The WCD now has dedicated addresses for each handover mode, ensuring correct routing without interference.
2Device complexity
If the WCD uses a single IMS transfer-address for all handovers, then the device complexity is reduced, but handover failures occur when transitioning between different RAN types
Solution Approach 1:
The patent implements a dynamic address selection mechanism where the WCD automatically chooses the appropriate IMS transfer-address based on the current handover scenario. The system dynamically determines whether SRVCC or DRVCC is being performed and selects the corresponding address. This dynamic adaptation allows the system to maintain simplicity in operation (the WCD doesn't need to manually configure addresses) while achieving high reliability through context-aware address selection.
3Reliability
If the WCD stores multiple IMS transfer-addresses for different handover types, then handover reliability is improved, but the device complexity increases
Solution Approach 1:
The patent enables the WCD to autonomously manage multiple IMS transfer-addresses without requiring complex external configuration or intervention. The device automatically receives the appropriate addresses from the network, stores them in association with their respective handover types (SRVCC/DRVCC), and independently selects the correct address during handover operations. This self-service capability allows the WCD to handle the complexity of multiple addresses internally while presenting a simple interface to the user and network.
4Ease of operation
If the WCD selects the wrong IMS transfer-address during handover, then signaling messages are incorrectly routed, but the WCD could otherwise support seamless handover
Solution Approach 1:
The patent implements a feedback mechanism where the WCD determines the appropriate handover type (SRVCC or DRVCC) based on current network conditions and device state, then uses this information to select the corresponding IMS transfer-address. The system continuously monitors handover requirements and adjusts address selection accordingly, ensuring that the correct routing information is always used. This feedback loop prevents the loss of routing information by actively matching the selected address to the actual handover scenario.
Data Source
AI summary
A wireless communication device (WCD) is configured to receive and maintain concurrently in data storage at least two different IMS transfer-addresses, such as one for use when the WCD's transition between radio access networks (RANs) is a single-radio transition and the other for use when the WCD's transition between RANs is a dual-radio transition, and/or one for use when the WCD's transition between RANs is packet-to-packet and the other for use when the WCD's transition between RANs is packet-to-circuit. Upon transitioning between RANs, the WCD may then select the appropriate one of these IMS transfer-addresses and transmit the selected IMS transfer-address to a network node to facilitate handover of an ongoing call to be via the WCD's new serving RAN.