System and method for controlling congestion in multihopping wireless networks
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 ).
1. A method for controlling congestion in an ad-hoc wireless communication network, the method comprising:
establishing a communication route from a source node to a destination node, at least one of the source node and destination node being in the ad-hoc wireless communication network;
detecting congestion by a congested node, along the communication route, based on dynamic behavior of the congested node and at least one neighboring node associated with the congested node, and channel and traffic characteristics of the ad-hoc wireless communication network;
when congestion is detected at the congested node, operating the congested node to send a congestion warning message for delivery to a source node via at least one intermediate node in the route that forward packets addressed to the destination node through the congested node, wherein the congestion warning message includes a congestion metric, and further wherein the congestion warning message informs the source node and the at least one intermediate node to regulate packet flow that contributes to the congestion in the communication route; and
operating the source node, and the at least one intermediate node to each set a timeout value representing a duration of congestion at the congestion node based on information included in the congestion warning message.
2. The method of claim 1 , wherein:
the step of operating the congested node when congestion is detected at the congested node comprises operating the congested node to send the congestion warning message to a precursor node for which the congested node acts as a next hop for packets addressed to the destination node that are transmitted by the precursor node.
3. The method as claimed in claim 2 , further comprising:
after the congested node sends the congestion warning message to the precursor node, operating the nodes in the route to continue to forward the congestion warning message along a reverse route to the source node.
4. The method as claimed in claim 1 , wherein:
the step of operating the congested node when congestion is detected at the congested node comprises operating the congested node to unicast or broadcast the congestion warning message along a reverse route to the source node.
5. The method as claimed in claim 1 , further comprising:
operating the nodes in the route that receive the congestion warning message to control packet traffic to the congested node.
6. The method as claimed in claim 1 , further comprising:
operating the nodes in the route that receive the congestion warning message to change the route to avoid the congested node.
7. The method as claimed in claim 1 , wherein:
one of the source node and the destination node is in the ad-hoc wireless communication network, and one of the source node and the destination node is in a different network, and one of the nodes in the route is an ingress node between the ad-hoc wireless network and the different network; and
the method further comprises operating the ingress node to perform traffic control in response to the congestion warning message.
8. The method as claimed in claim 1 , further comprising:
operating the nodes in the route that receive the congestion warning message to set the timeout value representing the duration of the congestion at the congested node.
9. The method as claimed in claim 1 , wherein:
at least one node in the route comprises multiple transceivers; and
the method further comprises operating the multiple transceiver node to control traffic through the interface between the multiple transceivers in response to the congestion warning message.
10. The method as claimed in claim 1 , wherein:
the congestion warning message comprises at least one of an address of the destination node and the congestion metric representing congestion at the congested node.
11. An ad-hoc wireless communication network, comprising:
a plurality of nodes, comprising a source node and a destination node, the source node operating to communicate with the destination node via a route comprising at least one of the plurality of nodes;
each node in the route operating to identify whether it is a congested node based on dynamic behavior of the congested node and at least one neighboring node associated with the congested node, and channel and traffic characteristics of the ad-hoc wireless communication network and, in response, sending a congestion warning message for delivery to the source node via at least one other node in the route that forwards packets addressed to the destination node through the congested node, wherein the congestion warning message, includes a congestion metric, and further wherein the congestion warning message informs the source node and the at least one other node, to regulate packet flow that contributes to the congestion in the communication route; and
the source node and the at least one other node in the route, operating to each set a timeout value representing a duration of congestion at the congestion node based on information included in the congestion warning message.
12. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
the congested node is further sends the congestion warning message to a precursor node for which the congested node acts as a next hop for packets addressed to the destination node that are transmitted by the precursor node.
13. The ad-hoc wireless communication network as claimed in claim 12 , wherein:
the at least one other node in the route continues to forward the congestion warning message along a reverse route to the source node.
14. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
the congested node unicasts or broadcasts the congestion warning message along a reverse route to the source node.
15. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
each node in the route and the source node that receives the congestion warning message control packet traffic to the congested node.
16. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
each node in the route and the source node that receives the congestion warning message change the route to avoid the congested node.
17. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
one of the source node and the destination node is in the wireless communication network and one of the source node and the destination node is in a different network, and one of the nodes in the route is an ingress node between the wireless network and the different network; and
the ingress node performs traffic control in response to the congestion warning message.
18. The ad-hoc wireless communication network as claimed in claim 11 , further comprising:
said at least one other node in the route that receives the congestion warning message sets the timeout value representing the duration of the congestion at the congested node.
19. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
at least one node in the route comprises multiple transceivers; and
the node comprising the multiple transceivers controls traffic through the interface between the multiple transceivers in response to the congestion warning message.
20. The ad-hoc wireless communication network as claimed in claim 11 , wherein:
the congestion warning message comprises at least one of an address of the destination node and a congestion metric representing congestion at the congested node.