IP Multicast Congestion Control via ECN and Packet Counting
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Solution Overview
Problem
Existing reliable IP multicast protocols are not optimized for radio-based transmission systems, leading to unnecessary reduction in transmission rates due to intermittent radio signal blockages, which can exacerbate congestion and decrease system throughput.
Innovation Solution
Implementing a congestion control method that adjusts transmission rates based on a count of congestion marked packets and dropped packets, using protocols like ECN and RED, to differentiate between light and heavy blockage conditions, thereby maintaining high channel transmission rates under light blockage and reducing rates under heavy blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP congestion control algorithms are used in existing reliable multicast protocols to determine transmission rates, then transmission rates are reduced in response to estimated round trip time increases, but this unnecessarily decreases system throughput under light blockage conditions
Solution Approach 1:
The patent changes the parameters used for congestion detection by introducing ECN marked packet counting and dropped packet counting as alternative or complementary metrics to round trip time estimation. This allows the system to differentiate between congestion-caused losses and blockage-caused losses, maintaining high transmission rates when blockages are the primary cause while still providing reliable transmission.
Solution Approach 2:
The patent implements feedback mechanisms where receiver devices send congestion status messages back to transmitter devices, containing information about ECN marked packets and dropped packets. This feedback loop enables transmitters to adjust transmission rates based on actual congestion conditions rather than relying solely on round trip time, which can be inflated by blockages.
2Reliability
If transmission rates are throttled back in response to radio signal blockages, then estimated round trip time increases are addressed, but transmission queue congestion is not cleared and system congestion is exacerbated
Solution Approach 1:
The patent segments the congestion control mechanism into distinct components: ECN marking at the network layer, separate packet counting at the application layer, and differentiated response strategies. This segmentation allows the system to handle congestion and blockage separately, using appropriate responses for each condition without requiring a completely new control mechanism.
Solution Approach 2:
The patent introduces ECN marking as an intermediary mechanism that provides explicit congestion notification without requiring full retransmission or rate reduction. ECN marked packets serve as a signal to the receiver to note congestion conditions, which are then reported back to the transmitter through congestion status messages, enabling fine-grained control without drastic rate changes.
3Adaptability or versatility
If existing reliable IP multicast protocols are used over radio-based transmission systems, then standardized protocols are implemented, but intermittent radio signal blockages have significant adverse impact on performance
Solution Approach 1:
The patent makes the congestion control mechanism universal by implementing it as an extension that works with existing standardized multicast protocols like NORM. The ECN marking and packet counting mechanisms can be applied to any TCP-friendly multicast protocol, providing improved reliability for radio-based systems without requiring protocol-specific customization.
Solution Approach 2:
The patent introduces dynamic adaptation by allowing the congestion control mechanism to adjust its behavior based on the detected cause of packet loss. When blockages are detected through ECN marking patterns and dropped packet counting, the system dynamically maintains higher transmission rates, whereas traditional protocols would statically reduce rates based on round trip time alone.
Data Source
AI summary
An IP multicast broadcast device, an IP multicast receiver device, and a method of congestion control in reliable IP multicast are described that mitigate the impact of signal blockage in radio-based IP multicast networks. In one example multicast network, the IP multicast broadcast device, and the IP multicast receiver devices may be configured to support an IGMP-based multicast protocol in which a NORM protocol, a congested packet marking protocol, e.g., such as the ECN protocol described above, and a router congestion prediction protocol, e.g., such as the RED protocol, have been implemented. In addition, the implemented NORM protocol may implement a TCP congestion control algorithm that generates adjusted transmission rates based, at least in part, on a count of ECN congestion marked packets and a count of dropped packets at a selected receiver. As a result, the generated transmission rates are not unduly affected blockage of the radio-based transmission signal.