Packet Filter Synchronization for Seamless VoIP Handover
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Solution Overview
Problem
In wireless communications, especially during handovers from VoIP over EV-DO to circuit switched voice networks, the existing packet filters become obsolete due to changes in data connection end points, leading to potential data misdirection and loss, as the media gateway is interposed between hybrid access terminals, necessitating synchronized updates of packet filters to maintain quality of service.
Innovation Solution
A method is implemented to synchronize packet filters by establishing a new packet flow with a remote data connection end point, adding a new packet filter specifying the remote end point, and then removing the original filter, ensuring seamless handover and maintaining quality of service by using RSVP messages to manage packet filters at packet data serving nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a media gateway is interposed in the RTP path during handover, then handover from VoIP to circuit switched voice is enabled, but the original packet filter becomes obsolete and data loss occurs during the transition interval
Solution Approach 1:
The system performs preliminary actions by establishing the new packet filter at the PDSN before the old packet filter is removed. The new packet filter is configured with the media gateway's address and port number in advance, so that when the handover occurs, packets are already routed through the correct path, preventing data loss during the transition interval.
Solution Approach 2:
The system uses feedback mechanisms where the mobile station notifies the PDSN about the handover event and the new packet filter configuration. This feedback loop ensures that the PDSN updates its packet filters synchronously with the media gateway interposition, maintaining consistency between the control plane and data plane.
2Productivity
If packet filters are updated during the interval between media gateway interposition and RTP packet transmission, then the packet filter reflects the new routing, but packets may be misdirected during this interval
Solution Approach 1:
The packet filter update is performed as a preliminary action before the actual handover completion. The PDSN receives notification of the upcoming handover and proactively updates the packet filter to point to the media gateway, ensuring that no packets are misdirected during the transition period.
Solution Approach 2:
The system introduces an intermediary notification mechanism between the media gateway interposition event and the packet filter update. The mobile station acts as an intermediary, receiving the handover command and then notifying the PDSN to update the packet filter, ensuring synchronized updates without packet loss.
3Adaptability or versatility
If the RTP endpoint changes during a call, then dynamic anchoring model handover is achieved, but seamless service continuity cannot be provided without synchronized packet filter updates
Solution Approach 1:
The system implements feedback mechanisms where the mobile station informs the PDSN about RTP endpoint changes. The PDSN receives this feedback and synchronously updates the packet filter to reflect the new media gateway endpoint, ensuring seamless service continuity without requiring complex manual configurations.
Solution Approach 2:
The packet filter synchronization is performed as a preliminary action in response to the RTP endpoint change notification. The PDSN updates the packet filter before the handover is fully completed, ensuring that service continuity is maintained without interruption or data loss.
Data Source
AI summary
A method including establishing a first packet flow over a network between a first mobile device and a second mobile device said first mobile device coupled to a node having a first packet filter including an identifier and specifying a second mobile device as a first end point, interposing a remote data connection end point between said first and second mobile device, adding a second packet filter at said node including said identifier and specifying said remote data connection end point as a second end point, establishing a second packet flow between said first and second mobile devices via said remote data connection end point, and removing said first packet filter.