IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
UP-0363778
(2006-02-28)
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등록번호 |
US-7697456
(2010-05-20)
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발명자
/ 주소 |
- Ekl, Randy L.
- Johnson, Mark J.
- Metke, Anthony R.
- Pandey, Aparna
- Phillips, Joseph E.
- Ware, Christopher G.
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
4 인용 특허 :
10 |
초록
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Techniques are provided for selecting a root node in an ad hoc network that contains a plurality of nodes including a first node. According to one implementation of these techniques, a first node can receive a message from at least one of the other nodes. Each message includes a number of primary fa
Techniques are provided for selecting a root node in an ad hoc network that contains a plurality of nodes including a first node. According to one implementation of these techniques, a first node can receive a message from at least one of the other nodes. Each message includes a number of primary factors associated with a particular node regarding capabilities of the particular node. The primary factors associated with each node can then be evaluated, and an attempt can be made to select the root node based on the primary factors associated with each node. If the first node is unable to select the root node based on the primary factors associated with each node, then the root node can be selected based on secondary factors associated with each node.
대표청구항
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We claim: 1. A method of selecting a root node in an ad hoc network comprising a plurality of nodes including candidate root nodes, the method comprising at each node of the plurality of nodes: deciding, using primary factors regarding capabilities of the node, whether or not to nominate itself as
We claim: 1. A method of selecting a root node in an ad hoc network comprising a plurality of nodes including candidate root nodes, the method comprising at each node of the plurality of nodes: deciding, using primary factors regarding capabilities of the node, whether or not to nominate itself as a candidate root node, only candidate root nodes deciding to nominate themselves transmitting a candidate message to the other nodes of the plurality of nodes in the ad hoc network; receiving the message from each candidate root node, wherein each message comprises the primary factors associated with an originating node from which the message originates regarding capabilities of the originating node; adding each of the candidate root nodes to a candidate list; comparing the primary factors associated with each of the candidate root nodes in the candidate list; and attempting to select the root node based on the primary factors associated with each of the candidate root nodes, wherein each of the plurality of nodes deciding whether or not to nominate itself as a candidate root node comprises each node designating itself as being a priority node in which the node has priority in being selected as the root node, a non-priority node in which the node is permitted to be selected as the root node but does not have priority in being selected as the root node, or an excluded node in which the node is precluded as being selected as the root node, the primary factors including whether the originating node is a priority node or non-priority node, wherein comparing the primary factors comprises: determining, at each of the nodes, whether a number of priority nodes in the candidate list is greater than, less than or equal to one, and removing nodes other than the priority nodes from the candidate list, at each of the nodes, if the number of priority nodes is greater than one, and wherein attempting to select the root node comprises choosing the priority node as a root node, if the number of priority nodes is equal to one. 2. A method according to claim 1, wherein if the number of priority nodes is not one: wherein comparing primary factors associated with each of the nodes further comprises: determining a first number of nodes in the candidate list which are powered nodes, if the number of priority root nodes is zero or more than one; and removing nodes other than the powered nodes from the candidate list, if the number of powered nodes is greater than one; and wherein selecting the root node further comprises choosing the powered node as the root node, if the number of powered nodes is equal to one. 3. A method according to claim 2, wherein if the number of powered nodes is not one: wherein comparing primary factors associated with each of the nodes further comprises: determining a second number of nodes in the candidate list which are fixed nodes, if the number of powered nodes is zero or more than one; and removing nodes other than the fixed nodes from the candidate list, if the number of fixed nodes is greater than one; and wherein selecting the root node, further comprises choosing the fixed node as the root node, if the number of fixed nodes is equal to one. 4. A method according to claim 1, wherein the candidate nodes comprises a current root node. 5. A method according to claim 1, further comprising prior to selecting the root node, a current root node renouncing its root node status after a predetermined period of time from being selected as the current root node by announcing expiration of its root node status to neighbor nodes. 6. A method according to claim 1, further comprising prior to selecting the root node, a current root node renouncing its root node status based on changes in its primary factors by announcing expiration of its root node status to neighbor nodes. 7. A method according to claim 1, further comprising each of the nodes waiting for an evaluation period after selecting the root node before attempting to select a new root node, wherein unless the root node leaves the ad hoc network another new root node cannot be selected until the evaluation period elapses. 8. A method according to claim 1, further comprising selecting a backup root node at the same time as selecting the root node, the backup root node being selected using the same characteristics to select the root node but excluding the root node, wherein when the root node recognizes that it will no longer be a member of the ad hoc network in the imminent future, the root node sends a renunciation message indicating that the root node is no longer going to be available to the network prior to no longer being a member of the network, the backup root node taking over as the root node after the renunciation message is transmitted by the root node. 9. A method according to claim 1, further comprising selecting a backup root node at the same time as selecting the root node, only an immediate neighbor of the new root node being able to be selected as the backup root node, wherein when the root node recognizes that it will no longer be a member of the ad hoc network in the imminent future, the root node sends a renunciation message indicating that the root node is no longer going to be available to the network prior to no longer being a member of the network, the backup root node taking over as the root node after the renunciation message is transmitted by the root node. 10. A method according to claim 9, further comprising selecting a plurality of backup root nodes, the root node prioritizing the backup root nodes such that when the root node is no longer available, a highest priority backup node assumes the role of the root node and each backup root node of lower priority than the highest priority backup node assumes the role of the backup root node of immediately higher priority. 11. A method according to claim 10, further comprising each backup root node monitoring its own parameters, determining whether certain parameters fall below a predetermined threshold, and, if so, then transmitting a message indicating that it is no longer one of the backup root nodes. 12. A method according to claim 1, wherein each candidate root node broadcasts its message periodically. 13. A method according to claim 1, wherein each candidate nodes broadcasts its message after at least one of its primary factors has changed significantly. 14. A method according to claim 1, wherein each of the plurality of nodes deciding whether or not to nominate itself as a candidate root node comprises each node designating itself as being a priority node in which the node has priority in being selected as the root node, a non-priority node in which the node is permitted to be selected as the root node but does not have priority in being selected as the root node, or an excluded node in which the node is precluded as being selected as the root node, the primary factors including whether the originating node is a priority node or non-priority node, wherein the primary factors comprise the number of priority nodes, the number of powered nodes, and the number of fixed nodes, each of the primary factors having a ranking, wherein comparing the primary factors comprises: determining, at each of the nodes, whether the number of nodes in the candidate list satisfying a highest ranking primary factor is greater than, less than or equal to one; and if the number of nodes satisfying the highest ranking primary factor is greater than one, removing nodes other than the nodes satisfying the highest ranking primary factor from the candidate list; wherein selecting the root node comprises: choosing the node satisfying the highest ranking primary factor as the root node, if the number of nodes satisfying the highest ranking primary factor is equal to one; and repeating the comparing and selecting for lower ranking primary factors in order of the ranking if the number of nodes satisfying each higher ranking primary factor is not one. 15. In an ad hoc network comprising a plurality of nodes configured to select a root node for the ad hoc network, the plurality of nodes comprising candidate root nodes, wherein each node comprises: a receiver configured to receive a message from each of the candidate root nodes, wherein each message comprises at least one of a number of primary factors associated with an originating node from which the message originates regarding capabilities of the originating node; and a processor configured to: compare primary factors associated with each of the candidate root nodes, attempt to select a new root node based on a result of comparing the primary factors associated with each of the candidate root nodes, decide, using its primary factors, whether or not to nominate itself as a root node candidate, the receiver receiving messages only from those nodes that have nominated themselves as root node candidates, determine from the message whether the originating node is a priority node in which the node has priority in being selected as the root node or a non-priority node in which the node is permitted to be selected as the root node but does not have priority in being selected as the root node, store each of the nodes which is a root node candidate in a candidate list at each of the nodes, determine whether the number of priority nodes in the candidate list is greater than, less than or equal to one, remove nodes other than the priority nodes from the candidate list if the number of priority nodes is greater than one, and select the priority node as the new root node, if the number of priority nodes is equal to one. 16. The nodes according to claim 15, wherein, if the number of priority root nodes is zero or more than one, the processor is further configured to: determine from a first number of nodes in the candidate list which ones are powered nodes, remove nodes other than the powered nodes from the candidate list, if the number of powered nodes is greater than one, and select the powered node as the root node, if the number of powered nodes is equal to one. 17. The nodes according to claim 16, wherein, if the number of powered nodes is zero or more than one, the processor is further configured to: determine a second number of nodes in the candidate list which are fixed nodes, remove nodes other than the fixed nodes from the candidate list, if the number of fixed nodes is greater than one, and select the fixed node as the root node, if the number of fixed nodes is equal to one. 18. The nodes according to claim 15, wherein the candidate nodes comprises a current root node. 19. The nodes according to claim 15, wherein each of the nodes is configured to wait for an evaluation period after selecting the new root node before attempting to select another new root node in the ad hoc network. 20. The nodes according to claim 15, wherein prior to each of the nodes selecting the new root node, a current root node renounces its status as a root node after a predetermined period of time from being selected as the current root node by announcing expiration of its root node status to neighbor nodes. 21. The nodes according to claim 15, wherein prior to each of the nodes selecting the new root node, a current root node renouncing its status as a root node based on changes in its primary factors by announcing expiration of its root node status to neighbor nodes. 22. The nodes according to claim 15, wherein each of the nodes selects a backup root node at the same time as selecting the new root node, the backup root node being selected using the same characteristics to select the new root node but excluding the new root node, wherein when the new root node recognizes that it will no longer be a member of the ad hoc network in the imminent future, the new root node sends a renunciation message indicating that the new root node is no longer going to be available to the network prior to no longer being a member of the network, the backup root node taking over as the new root node after the renunciation message is transmitted by the new root node. 23. The nodes according to claim 15, wherein each of the nodes selects a backup root node at the same time as selecting the new root node, only an immediate neighbor of the new root node being able to be selected as the backup root node, wherein when the new root node recognizes that it will no longer be a member of the ad hoc network in the imminent future, the new root node sends a renunciation message indicating that the new root node is no longer going to be available to the network prior to no longer being a member of the network, the backup root node taking over as the new root node after the renunciation message is transmitted by the new root node. 24. The nodes according to claim 23, wherein each of the nodes selects a plurality of backup root nodes, the new root node prioritizing the backup root nodes such that when the new root node is no longer available, a highest priority backup node assumes the role of the new root node and each backup root node of lower priority than the highest priority backup node assumes the role of the backup root node of immediately higher priority. 25. The nodes according to claim 24, further comprising each backup root node monitors its own parameters, determining whether certain parameters fall below a predetermined threshold, and, if so, then transmits a message indicating that it is no longer one of the backup root nodes. 26. A method of selecting a root node in an ad hoc network comprising a plurality of nodes including candidate root nodes, the method comprising at each node of the plurality of nodes: deciding, using primary factors regarding capabilities of the node, whether or not to nominate itself as a candidate root node, only candidate root nodes deciding to nominate themselves transmitting a candidate message to the other nodes of the plurality of nodes in the ad hoc network; receiving the message from each candidate root node, wherein each message comprises the primary factors associated with an originating node from which the message originates regarding capabilities of the originating node; adding each of the candidate root nodes to a candidate list; comparing the primary factors associated with each of the candidate root nodes in the candidate list; attempting to select the root node based on the primary factors associated with each of the candidate root nodes; and prior to selecting the root node, a current root node renouncing its root node status, either after a predetermined period of time from being selected as the current root node or based on changes in its primary factors, by announcing expiration of its root node status to neighbor nodes.
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