FEC Spatial Diversity for Video Packet Loss Recovery
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Solution Overview
Problem
Existing video delivery systems face challenges in providing loss-free video due to packet loss caused by congestion, link errors, and re-routing events, especially in packet-switched or label-switched core networks, where outages can take 50-500 milliseconds to recover, leading to lost packets during this time.
Innovation Solution
Implementing Forward Error Correction (FEC) spatial diversity by sending source packets over one media path and FEC repair packets over a different path, allowing for reduced repair packet overhead and faster recovery during network outages, while also providing load balancing and dynamic adaptation of FEC data based on monitored outage durations and latency budgets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Forward Error Correction (FEC) is used to repair packet loss, then video delivery reliability is improved, but repair packet overhead increases
Solution Approach 1:
The patent transitions from temporal diversity (sending source and repair packets over the same path at different times) to spatial diversity (sending source and repair packets over different media paths simultaneously). This dimensional change in packet transmission strategy reduces repair packet overhead by 50% while maintaining video delivery reliability, as source packets and repair packets can be lost independently on different paths.
2Device complexity
If temporal diversity is used to send source and repair packets over the same path, then implementation complexity is reduced, but repair packet overhead increases by 50%
Solution Approach 1:
The patent introduces spatial diversity by transmitting source packets and repair packets over different media paths rather than using temporal diversity on the same path. This dimensional change reduces repair packet overhead by 50% while the complexity increase is manageable through systematic path selection and monitoring mechanisms.
3Reliability
If network outages are handled with traditional re-routing, then path recovery is achieved, but packet loss occurs during the 50-500ms convergence time
Solution Approach 1:
The patent prepares repair packets in advance using Forward Error Correction encoding and transmits them proactively over alternative media paths before outages occur. When an outage is detected on the source packet path, the pre-positioned repair packets are already available on alternative paths, enabling immediate packet recovery without the 50-500ms convergence delay of traditional re-routing methods.
Solution Approach 2:
The patent introduces repair packets as intermediary elements that mediate between source packets and the receiver. These repair packets travel over alternative media paths and serve as substitutes for lost source packets, enabling continuous video delivery during network outages without requiring direct path recovery.
4Productivity
If selectivity retransmission is used to repair packet loss, then bandwidth efficiency is improved, but round-trip time must be very short
Solution Approach 1:
The patent performs preliminary encoding of repair packets using Forward Error Correction before transmission. This allows repair packets to be prepared and sent in advance over alternative paths, eliminating the need for interactive retransmission protocols and their associated round-trip time constraints, while maintaining bandwidth efficiency through selective transmission of only necessary repair packets.
Data Source
AI summary
A media source sends media packets over a first media path. Repair packets are encoded from the media source packets and sent over a second different media path. Sending the source packets and repair packet over different media paths is referred to as Forward Error Correction (FEC) spatial diversity and reduces the amount of repair packet overhead required for repairing the media source packets in case of a network outage or packet loss. To provide load balancing, a first set of media streams may be sent over the first media path and a second set of media streams may be sent over the second media path. If a fault is detected on one of the media paths, then the repair packets may no longer be transmitted and the one or more media streams from the disabled media path are transmitted over the working media path.