Mobile IP Session Transition via Preliminary Agent Solicitation
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Solution Overview
Problem
Current cdma2000 wireless IP networks lack a mechanism for a mobile device in a dormant SIP session to transition to a MIP session when it reconnects to a network that supports MIP, leading to potential service disruptions and inability to maintain 'always-on' connectivity.
Innovation Solution
A method and device for detecting new systems requiring packet data service reconnection, storing MIP support information, and attempting to establish a MIP session if previously supported, or falling back to SIP if not, by sending unsolicited agent solicitations and managing session types based on network parameters and IPCP configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mobile device uses SIP protocol with geographically dependent IP addresses, then the device can be assigned IP addresses dynamically by visited PDSN, but the device cannot maintain consistent connectivity for push services when moving between networks
Solution Approach 1:
The mobile device proactively sends an unsolicited Agent Solicitation message when detecting a new system, before the network can assign a new SIP IP address. This preliminary action allows the device to discover MIP-capable networks and establish MIP sessions in advance, ensuring continuous connectivity for push services without waiting for network-initiated address assignment changes.
Solution Approach 2:
The patent introduces an intermediary mechanism (Agent Solicitation/Advertisement exchange) between the mobile device and the network to discover MIP capabilities. This intermediary process enables the device to identify MIP-capable PDSNs and transition from SIP to MIP protocol, serving as a bridge that maintains connectivity consistency while adapting to different network environments.
2Duration of action of stationary object
If a mobile device maintains dormant PPP connectivity in SIP mode, then the device can preserve link layer connectivity, but the PDSN may tear down the PPP session when the device is out of coverage, breaking push services
Solution Approach 1:
When the mobile device detects a new system while in dormant state, it proactively initiates an Agent Solicitation to discover MIP capabilities before the PDSN can tear down the PPP session. This preliminary discovery action allows the device to transition to MIP mode in advance, preventing the PDSN from unilaterally terminating the connection and ensuring push service continuity.
Solution Approach 2:
The patent enables dynamic protocol switching between SIP and MIP based on network capabilities. The mobile device adapts its IP protocol dynamically - using SIP when appropriate but switching to MIP when MIP-capable networks are detected, particularly in dormant state. This dynamic adaptation allows the device to maintain reliable push services by selecting the appropriate protocol based on real-time network conditions.
3Ease of operation
If the IS-835 standard requires falling back to SIP mode when MIP session establishment fails, then the device can establish a data session, but the device loses the ability to maintain always-on connectivity when visiting MIP-capable networks
Solution Approach 1:
The mobile device performs preliminary MIP capability discovery by sending an unsolicited Agent Solicitation message before attempting data session establishment. This preliminary action allows the device to identify MIP-capable networks in advance and initiate MIP session establishment proactively, rather than defaulting to SIP mode and losing always-on connectivity capabilities.
Solution Approach 2:
The patent inverts the conventional approach by having the mobile device initiate MIP capability discovery (sending Agent Solicitation) rather than waiting for the network to offer MIP services. This inversion allows the device to actively seek out and establish MIP sessions on MIP-capable networks, reversing the traditional SIP-first fallback behavior and enabling always-on connectivity when MIP is available.
Data Source
AI summary
Methods are provided for transitioning between SIP and MIP. Mobile devices, upon detecting a new system, automatically attempt a MIP session to avoid the default position of SIP. A history is maintained of systems visited, and for systems that did not support MIP in the past, a MIP session is not attempted, but rather SIP is initiated from the start.