Repair Feedback Signaling for Point-to-Multipoint File Delivery
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Solution Overview
Problem
In point-to-multipoint transmission systems, existing protocols face challenges in reliable file delivery due to the inability to efficiently identify and retransmit missing data packets, particularly with FEC schemes that use rate-less codes like LT or Raptor codes, where the FEC Payload ID does not include SBN, making it difficult for receivers to signal specific packet losses.
Innovation Solution
A method where receivers signal the number of correctly received data packets to a repair server, allowing it to determine and transmit necessary repair data packets, reducing the need for exact packet identification and minimizing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If receivers use FEC schemes like Raptor codes without exact packet identification, then signaling overhead is reduced, but the ability to identify missing data packets is lost
Solution Approach 1:
The receiver sends feedback to the transmitter indicating the number of correctly received data packets. The transmitter uses this feedback to determine how many repair data packets to generate and transmits them accordingly. This feedback mechanism enables the system to operate without exact packet identification while maintaining efficient repair transmission.
Solution Approach 2:
The transmitter autonomously determines the number of repair data packets needed based on the feedback received about correctly received packets. Instead of requiring the receiver to precisely identify which packets are missing, the transmitter self-adjusts the repair transmission based on the quantitative feedback, eliminating the need for complex packet identification protocols.
2Reliability
If point-to-point ACK protocols like TCP are used for reliable file delivery, then delivery reliability is improved, but they are not feasible for point-to-multipoint scenarios
Solution Approach 1:
The invention segments the reliable delivery mechanism into two parts: (1) unidirectional FEC-based data transmission from transmitter to multiple receivers, and (2) simplified feedback from receivers to transmitter indicating only the count of correctly received packets. This segmentation adapts TCP-like reliability to point-to-multipoint by removing the need for complex per-packet acknowledgments while maintaining delivery assurance.
Solution Approach 2:
The feedback mechanism serves multiple functions: it informs the transmitter about reception status, enables automatic determination of repair packet needs, and works across point-to-multipoint scenarios without requiring protocol modifications. This universal feedback approach replaces protocol-specific ACK mechanisms with a scenario-agnostic solution.
3Manufacturing precision
If exact identification of missing data packets is implemented, then repair transmission precision is improved, but signaling overhead increases
Solution Approach 1:
Instead of providing exact packet identification information, the system uses partial information (the count of correctly received packets). The transmitter compensates for this partial information by generating and transmitting additional repair data packets that ensure reliable reconstruction, accepting some excess transmission in exchange for dramatically reduced signaling overhead.
Data Source
AI summary
This invention relates to a method, system, transmitter, network element, receiver and software application for a system capable of point-to-multipoint transmission, where one or more data packets are transmitted from a transmitter to one or more receivers, where at least at one specific receiver of said receivers, a reception of repair data packets is required, where repair information is signaled to a repair server in order to trigger a transmission of the repair data packets, and where the repair information comprises information related to the number of transmitted data packets correctly received at the specific receiver. The system may for instance be the 3GPP Multimedia Broadcast Multicast System, the transmission of data packets may for instance be controlled by the File Delivery Over Unidirectional Transport protocol and the signaling of the repair information may for instance be controlled by the Hypertext Transfer Protocol.