Remote Presentation Transport Using ARQ and FEC on Lossy Networks
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Solution Overview
Problem
Remote presentation protocols over wide area networks face delays and data packet loss due to high round trip time and data packet loss, leading to negative impacts on real-time user experience, such as tearing and jitter.
Innovation Solution
Integration of the remote presentation protocol with a datagram-based transport that supports lossless or reduced loss transport using Retransmission (ARQ) combined with Forward Error Correction (FEC), dynamic evaluation of loss probability, congestion management, and fast data transmission rate ramp-up, allowing for in-order data delivery or reporting of data loss or out-of-order delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP-type connection is used for remote presentation protocol, then reliable data delivery is achieved, but round trip time and data packet loss cause delays that negatively impact real-time user experience
Solution Approach 1:
The patent segments the data transmission into multiple parallel channels including a first channel for control data and a second channel for presentation data. This segmentation allows different types of data to be transmitted with different reliability requirements, reducing the overall impact of retransmission delays on real-time user experience while maintaining necessary reliability for control functions.
Solution Approach 2:
The patent introduces an intermediary mechanism by using UDP as the transport protocol instead of TCP, combined with application-level reliability mechanisms. This intermediary approach decouples the transport layer from the reliability guarantee layer, allowing faster transmission while maintaining necessary reliability through selective acknowledgment and retransmission only when needed.
2Reliability
If retransmission (ARQ) is used for lossless transport, then packet loss is reduced, but transmission delay increases due to waiting for acknowledgments
Solution Approach 1:
The patent applies partial retransmission by selectively retransmitting only the lost presentation data packets rather than all transmitted packets. This partial action approach reduces the overall retransmission delay compared to full retransmission while still achieving lossless transport for the critical presentation data, thereby resolving the contradiction between reliability and transmission delay.
Solution Approach 2:
The patent implements preliminary action by sending forward error correction (FEC) packets along with the data packets. These FEC packets are prepared in advance and can be used to recover from packet loss without requiring retransmission, thus reducing transmission delay while maintaining reliability for time-sensitive presentation data.
3Speed
If datagram based transport is used for faster transmission, then real-time performance improves, but data packet loss and out-of-order delivery increase
Solution Approach 1:
The patent applies local quality by implementing different reliability mechanisms for different types of data. Control data transmitted over the first channel uses standard UDP with minimal reliability measures for speed, while presentation data over the second channel uses selective acknowledgment and retransmission mechanisms. This local differentiation allows fast transmission overall while maintaining reliability where needed, resolving the speed-reliability contradiction.
Solution Approach 2:
The patent implements feedback mechanisms through selective acknowledgment packets sent from the client to the server. This feedback allows the server to identify which presentation data packets were lost and retransmit only those specific packets, thereby reducing packet loss rate while maintaining the fast datagram-based transmission for real-time performance.
Data Source
AI summary
In various embodiments, methods and systems are disclosed for integrating a remote presentation protocol with a datagram based transport. In one embodiment, an integrated protocol is configured to support lossless or reduced loss transport based on Retransmission (ARQ) combined with Forward Error Correction (FEC). The protocol involves encoding and decoding of data packets including feedback headers and FEC packets, continuous measurement of RTT, RTO and packet delay, dynamically evaluating loss probability to determine and adjust the ratio of FEC, congestion management based on dynamically detecting increase in packet delay, and fast data transmission rate ramp-up based on detecting a decrease in packet delay.