TCP Deadlock Resolution via Duplicate ACKs During Handover
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Solution Overview
Problem
Mobile devices experience significant data loss and delay during communication technology handovers due to differences in protocol standards, leading to TCP deadlocks and prolonged waiting periods for retransmissions.
Innovation Solution
A mobile device with a modem and TCP layer that detects changes in communication protocol standards and initiates the transmission of three duplicate ACK packets upon handover completion, directly communicating with the TCP layer to resume data transfer quickly and minimize delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile device waits for standard TCP retransmission timeout after packet loss during handover, then the TCP protocol stability is maintained, but the data transfer delay increases significantly
Solution Approach 1:
The mobile device proactively sends duplicate ACK packets immediately upon detecting handover completion, before the standard TCP retransmission timeout expires. This preliminary action prevents the timeout from occurring in the first place, thereby avoiding the delay while maintaining TCP protocol stability through proper acknowledgment of received packets.
Solution Approach 2:
The invention changes the acknowledgment behavior parameter by sending three duplicate ACK packets instead of waiting for the natural TCP retransmission timeout mechanism. This parameter change accelerates the resumption of data transfer after handover while still adhering to TCP protocol rules for packet acknowledgment.
2Productivity
If the mobile device sends duplicate ACK packets immediately after handover completion, then the data transfer resumption speed is improved, but the risk of spurious ACKs increases
Solution Approach 1:
The mobile device uses feedback from the handover completion detection to trigger the sending of duplicate ACK packets. The feedback mechanism ensures that duplicate ACKs are sent only when actually needed (after handover completion) rather than indiscriminately, reducing the risk of spurious ACKs while maintaining fast data transfer resumption.
Solution Approach 2:
By preparing and sending the duplicate ACK packets as a preliminary action immediately upon handover completion, the device ensures that the ACKs are sent at the precise moment when they are needed to resume data transfer, avoiding both premature sending (which could cause spurious ACKs) and delayed sending (which would reduce productivity).
Data Source
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AI summary
A mobile device comprises physical layer circuitry including a transceiver configured to communicate information via the cellular communication network; a modem of the mobile device configured to: control communication according to a first cellular communication protocol standard; detect a change in the communication to a second cellular communication protocol standard different from the first cellular communication protocol standard; and communicate an indication of completion of the change in the cellular communication protocol standard; and a transport control protocol (TCP) layer of the mobile device configured to initiate transmission of three duplicate acknowledgment (ACK) packets according to the second cellular communication protocol standard in response to receiving the indication of completion of the change in the cellular communication protocol standard.