Congestion Control in Multihop Wireless Networks
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Solution Overview
Problem
In wireless multihopping networks, congestion control is unreliable due to the failure of existing methods to consistently distribute congestion information to source nodes, leading to persistent bottlenecks and network instability.
Innovation Solution
A system and method that distributes congestion information back to ingress points and traffic sources along the data flow path, allowing nodes to avoid bottleneck points without a central controller, using routing metrics and congestion warning messages to regulate traffic and maintain fairness and service differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suppression messages are broadcasted by devices in the network to reduce traffic, then congestion control is attempted, but the reliability of receiving these messages is low and they may not always be received by the sources
Solution Approach 1:
The patent implements feedback by having intermediate nodes send congestion notification messages back to source nodes along the reverse routing path. This feedback mechanism ensures that congestion information reaches the sources reliably, enabling them to adjust their traffic generation rates accordingly.
Solution Approach 2:
Instead of broadcasting suppression messages upstream from congested nodes (the conventional approach), the patent inverts the approach by having intermediate nodes send congestion notifications back to the sources along the reverse routing path. This inversion ensures more reliable message delivery to sources.
2Reliability
If nodes broadcast suppression messages to avoid congestion, then traffic reduction is attempted, but nodes may choose not to propagate messages if local network conditions are acceptable
Solution Approach 1:
The system establishes a feedback mechanism where intermediate nodes automatically send congestion notifications back to source nodes. This ensures consistent message propagation regardless of local network conditions, as the notification is triggered by the actual congestion state rather than node discretion.
Solution Approach 2:
The routing protocol pre-establishes reverse routing paths and congestion notification mechanisms before congestion occurs. When congestion is detected, the pre-configured feedback path is activated immediately, ensuring consistent and reliable message propagation without waiting for node decisions.
3Reliability
If a central controller is used to manage congestion, then congestion control would be more effective, but the system becomes more complex and less scalable
Solution Approach 1:
The patent implements self-service congestion control where individual nodes autonomously detect congestion conditions and send notifications along reverse routing paths. Source nodes independently receive these notifications and adjust their own traffic rates, eliminating the need for a central controller while maintaining effective congestion management.
Solution Approach 2:
The congestion control function is segmented into distributed operations at individual nodes rather than centralized control. Each intermediate node independently monitors its own congestion state and sends notifications, while source nodes independently process notifications and adjust traffic, creating a modular and scalable system.
Data Source
AI summary
A system and method to control congestion in a multihopping wireless communication network (100). The system and method distribute the congestion information back to the ingress points (106) and traffic source nodes (102, 106, 107) in the network (100) through the actual route of the data flow that contributes to the congestion. The system and method therefore avoid bottleneck points (102-5) in the network (100) to reduce congestion. The system and method can be used for packet-based, route-based or flow-based traffic shaping in a multihop wireless network (100) employing different media access control (MAC) and routing layer protocols. Moreover, the system and method is capable of distributing congestion and service differentiation information between different interfaces in the network (100).