Loop-Free Ad-Hoc Routing via Distributed Ordered Sequence
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Solution Overview
Problem
Existing wireless ad-hoc networks face challenges in maintaining loop-free and stable routes due to dynamic network topology changes, with existing routing schemes prone to looping, oscillation, convergence failure, and label space overflow.
Innovation Solution
The Distributed Ordered Sequence (DOS) routing procedure ensures loop-free routing by using distributed ordered sequences for each destination, maintaining node labels in a strict topological order, and employing six procedures for passing routing messages, including node initialization, route-query initiation, and route-reply handling, to prevent loop formation and allow easy addition of nodes to existing routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If link-state routing (TBRPF/OLSR) is used to maintain routes for all destinations, then routing coverage is improved, but routing loops occur
Solution Approach 1:
The patent changes the parameter of route selection by introducing sequence numbers that nodes must strictly decrease along the routing path. This parameter change ensures loop-free routing while maintaining comprehensive destination coverage, resolving the contradiction between routing coverage and loop-free operation.
Solution Approach 2:
The patent replaces the traditional link-state routing mechanism with an on-demand routing approach using sequence numbers. Instead of maintaining complete topology information, nodes only maintain routes to destinations with traffic, substituting the mechanical link-state system with a more efficient sequence-number-based system that prevents loops.
2Loss of energy
If on-demand routing (AODV/DYMO) is used to reduce network overhead, then network load is reduced, but route recovery causes loops or oscillation
Solution Approach 1:
The patent introduces sequence numbers as a new parameter that strictly decreases along routing paths. This parameter ensures that route recovery operations cannot create loops or oscillation, while maintaining the low network load characteristics of on-demand routing by only maintaining routes to active destinations.
Solution Approach 2:
The patent implements feedback through sequence number verification at each routing decision point. Nodes check that sequence numbers decrease along the path, providing continuous feedback that prevents loop formation during route recovery, thereby improving route stability without increasing network load.
3Adaptability or versatility
If DSR path-recovery technique is used to adapt to topology changes, then route adaptability is improved, but routing loops occur
Solution Approach 1:
The patent changes the route recovery mechanism by requiring strict sequence number decrease along the path. This parameter constraint ensures that even when nodes dynamically join or leave routes, the path-recovery process cannot create loops, maintaining both adaptability and loop-free operation.
4Reliability
If AODV/DYMO use sequence numbers for loop prevention, then loop-free routing is achieved, but label space overflow occurs during route recovery
Solution Approach 1:
The patent modifies the sequence number usage by requiring strict decrease rather than just increase. This parameter change prevents label space overflow during route recovery while maintaining loop-free routing, as nodes cannot accumulate unlimited sequence numbers along paths.
Data Source
AI summary
One embodiment of the present invention provides a system that facilitates loop-free ad-hoc routing in a wireless network. During operation, the system advertises a local sequence number associated with a local node for a destination node, and receives a first route request at the local node, wherein the route request specifies a source node, the destination node, and a first sequence number. The system further selectively maintains a record, which indicates the source node, the destination node, the first sequence number, and a node from which the route request is received. The system also selectively forwards a second route request based on the received route request, wherein the second route request specifies the source node, the destination node, and a second sequence number which is less than the first sequence number and less than or equal to the advertised local sequence number.