Lossless Handover via Target Node Data Buffering
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Solution Overview
Problem
Current 3GPP handover procedures in mobile telecommunications networks often result in data loss or delayed delivery of downlink data packets during handover, which is considered inevitable due to operating constraints, but it is desirable to avoid such losses without increasing signaling complexity or overhead.
Innovation Solution
Implementing a lossless handover procedure by buffering received user data packets at the target node during handover, where the source node stops transmitting data before sending a handover command and continues receiving data, and the mobile device stops transmitting data after receiving the command, allowing for seamless packet forwarding to the target node once a communication link is established.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data packets are forwarded from source eNodeB to target eNodeB during handover execution, then data loss is avoided, but signaling complexity and overhead increase
Solution Approach 1:
The source eNodeB performs preliminary actions by stopping downlink data transmission before sending the handover command, and by buffering any received downlink data packets. This preliminary stopping and buffering prevents data loss during handover without requiring complex forwarding mechanisms, as the data is already prepared and held ready for transmission to the target eNodeB after handover completion.
Solution Approach 2:
The patent extracts the data forwarding function from the handover signaling process. Instead of integrating data forwarding into the handover signaling (which would increase signaling complexity), the data forwarding is separated as an independent function that occurs after handover completion. The source eNodeB buffers data and forwards it separately through the X2 interface, decoupling these two operations.
2Reliability
If data packets are forwarded from source eNodeB to target eNodeB during handover execution, then data loss is avoided, but handover delay increases
Solution Approach 1:
The source eNodeB performs preliminary actions by stopping downlink data transmission before sending the handover command, and by buffering any received downlink data packets. This preliminary stopping and buffering prevents data loss during handover without requiring complex forwarding mechanisms, as the data is already prepared and held ready for transmission to the target eNodeB after handover completion.
3Adaptability or versatility
If different mechanisms are applied for real-time and non-real-time services during handover, then service-specific requirements are met, but system complexity increases
Solution Approach 1:
The patent applies a universal handover procedure that works for both real-time and non-real-time services. The source eNodeB stops downlink transmission and buffers data regardless of service type, and the target eNodeB forwards this buffered data after handover completion. This unified approach eliminates the need for service-specific mechanisms while still meeting the requirements of different service types through the common data forwarding mechanism.
Data Source
AI summary
A target node includes an S1 interface which includes an interface between the target node and a gateway, an X2 interface which includes an interface between a source node and the target node, and a transceiver which receives data from the S1 interface and data from the X2 interface. The transceiver sends the data from the X2 interface before sending the data from the S1 interface to a mobile device after the mobile device completes a handover from the source node to the target node.