Retransmission Priority Scheduling in TCP Media Transport
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Solution Overview
Problem
The transmission control protocol (TCP) causes out-of-order data packets due to retransmissions, leading to increased waiting delays and frame freezing during media playback in high-data-volume scenarios like ultra-high-definition video and virtual/augmented reality streaming.
Innovation Solution
A communication method involving user plane function network elements and access network elements to identify retransmitted data based on sequence number differences and priority scheduling, ensuring preferential transmission of retransmitted data to reduce waiting delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP in-sequence delivery is used to ensure reliable data transmission, then data reliability is improved, but waiting delay increases and frame freezing occurs during media playback
Solution Approach 1:
The patent segments the data transmission process into two independent queues: a retransmission queue for out-of-order packets and a normal transmission queue for in-order packets. This segmentation allows retransmitted packets to be sent immediately without blocking the entire data stream, thereby reducing waiting delay while maintaining TCP's reliable delivery mechanism.
Solution Approach 2:
The patent performs preliminary identification of retransmitted packets by comparing sequence numbers before they enter the normal transmission queue. By pre-classifying packets into retransmission or normal categories, the system avoids the need to wait for in-sequence delivery completion, enabling immediate transmission of retransmitted packets and reducing playback delay.
2Device complexity
If retransmitted data packets are sent through normal transmission queue, then network simplicity is maintained, but transmission delay increases and media playback freezes
Solution Approach 1:
The patent divides the transmission queue into two separate queues: a retransmission queue for out-of-order packets and a normal transmission queue for in-order packets. This segmentation enables differentiated transmission strategies - retransmitted packets are sent immediately from the retransmission queue without blocking the normal queue, thereby reducing transmission delay while maintaining manageable network complexity.
Solution Approach 2:
The patent applies different transmission qualities to different packet types: retransmitted packets receive priority treatment with immediate transmission, while normal packets follow standard TCP sequencing. This local quality differentiation ensures that retransmitted packets don't delay media playback without requiring complete system redesign, balancing performance improvement with implementation simplicity.
3Loss of time
If out-of-order data packets are transmitted immediately, then waiting delay is reduced, but TCP reliability mechanism is compromised
Solution Approach 1:
The patent segments packet handling into two independent paths: retransmitted packets are identified through sequence number comparison and routed to a dedicated retransmission queue, while normal packets continue through the standard TCP path. This segmentation allows immediate transmission of retransmitted packets without compromising TCP's reliability mechanism, as the normal in-sequence delivery remains intact.
Solution Approach 2:
The patent applies selective quality treatment locally to retransmitted packets by identifying them through sequence number analysis and directing them to priority transmission. This localized approach improves waiting delay for critical retransmitted packets while preserving the overall TCP reliability mechanism for normal packet delivery, achieving both goals simultaneously.
Data Source
AI summary
Embodiments of this application provide a communication method and apparatus, to reduce a waiting delay during transmission of retransmitted data and out-of-order data. In this method, a user plane function network element may receive first data and second data, determines a sending priority of the second data relative to the first data packet, and sends indication information to an access network network element. The indication information herein may indicate the sending priority of the second data relative to the first data packet. Based on this solution, the access network network element may send the first data and the second data based on the indication information, and may preferentially send the retransmitted data to reduce the waiting delay during data transmission.