Hard Handoff Blackout Reduction via Early Target Connection
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Solution Overview
Problem
Current wireless broadband data communications systems experience data blackouts during hard handoffs due to the interruption of data flow between access terminals and access networks, which is unacceptable for delay-sensitive applications like VoIP and Video Telephony, as existing technologies do not effectively minimize data loss during this transition.
Innovation Solution
A method is introduced where a communications path between the target access network and a packet data node is established prior to traffic channel assignment, allowing for bicasting or unicasting of user data packets, and the use of tunneling to relay data packets from the source to the target access network, thereby reducing the blackout period by initiating the target RP connection before traffic channel assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hard handoff procedure is used in HRPD systems, then connection switching between access networks is achieved, but data blackout period occurs during handoff
Solution Approach 1:
The patent applies preliminary action by establishing the target RP connection (between target PCF and PDSN) before the source RP connection is released. This is achieved through early A11 registration request messaging from the target AN to the PDSN, creating a forwarding path in advance. Data packets are forwarded through this pre-established target connection during the handoff transition, eliminating the traditional data blackout period that occurs when the source connection is terminated first.
Solution Approach 2:
The patent introduces a forwarding path as an intermediary mechanism between the PDSN and the target AN. This forwarding path acts as a mediator that temporarily carries data packets during the handoff transition. The forwarding path receives data from the PDSN and forwards it to the target AN before the regular data path is fully established, thus maintaining continuous data flow throughout the handoff process.
2Productivity
If source RP connection is released before target RP connection is established, then resource cleanup is achieved, but data loss occurs during handoff
Solution Approach 1:
The patent reverses the traditional sequence by performing preliminary action to establish the target RP connection before releasing the source RP connection. The target AN sends an A11 registration request to the PDSN in advance, and the PDSN sets up a forwarding path. This ensures that a valid data path exists before the old connection is torn down, preventing data loss while maintaining resource cleanup efficiency.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining data flow throughout the entire handoff process. The forwarding path continues to carry data packets from the PDSN to the target AN even as the source connection is being released. This continuous data transmission eliminates gaps in data delivery, ensuring reliability while resources are being reallocated.
Data Source
AI summary
Various embodiments are described to assist in reducing handoff delays and the blackout period(s) associated with inter AN (access network) hard handoffs. The hard handoff procedure of method disclosed herein establishes or initiates a connection (A10-type connection) between a target AN and a packet data serving node (PDSN), unlike known hard handoff approaches that wait until traffic channel assignment to establish or initiate such connection. The PDSN may optionally bicast data packets to both the source and target ANs since each is communicatively coupled to the PDSN during a given time period. In the event bicasting is unavailable or unused, a communication tunnel between the source and target ANs may be created and used to transmit data packets between them.