System and method for achieving continuous connectivity to an access point or gateway in a wireless network following an on-demand routing protocol, and to perform smooth handoff of mobile terminals between fixed terminals in the network

• US 20040143842A1
• Filed: 01/13/2004
• Published: 07/22/2004
• Est. Priority Date: 01/13/2003
• Status: Active Grant

• Current Assignee: Strong Force IoT Portfolio 2016, LLC (Strong Force Intellectual Capital, LLC)
• Original Assignee: MeshNetworks, Inc. (Motorola Solutions, Inc.)
• Inventors: Joshi, Avinash
• Granted Patent: US 7,522,537 B2
• Time in Patent Office: Days
• US Class Current: 725/32
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/28 for reactive routing
• CPC Class Codes: H04W 40/30 for proactive routing
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system and method for enabling an ad-hoc communication network to maintain connectivity with the mobile nodes in the network in an effective and efficient manner with minimal overhead. The system and method enables an ad-hoc communication network to maintain connectivity between intelligent access points of the network and mobile nodes in the network while performing an on-demand protocol. The system and method further uses an improved distance vector routing algorithm and unicast messages, to thus avoid an increase routing advertisement frequency in the network while keeping network overhead at a minimum. The system and method also modifies the Ad Hoc On-Demand Distance Vector Routing (AODV) protocol to facilitate smooth handoff of subscriber devices in an ad-hoc communication network while also eliminating unidirectional links between nodes in the network.

Claims

1. A method for maintaining a route to an access point in a wireless communication network, the method comprising:

transmitting an access point advertisement from the access point to at least one node of the network in a broadcast range of the access point;

transmitting a route request message from said at least one node to the access point upon receipt of the access point advertisement with desired criteria by said at least one node;

transmitting a reply message from the access point to said at least one node upon receipt of the route request message by the access point;

rebroadcasting the access point advertisement from said at least one node to at least one other node of the network in a broadcast range of said at least one node;

transmitting a route request message from said at least one other node to said at least one node upon receipt of the rebroadcast access point advertisement with desired criteria by said at least one other node;

if a destination only flag of the route request message from said at least one other node is not set, the transmitting a reply message from said at least one node to said at least one other node, and a gratuitous reply message from said at least one node to the access point, upon receipt of the route request message by said at least one node; and

if the destination only flag of the route request message is set, then forwarding the route request message from said at least one node to the access point.

2. A method as claimed in claim 1, wherein:

the network is a wireless ad-hoc peer-to-peer network, and said at least one node and said at least one other node communicate in the wireless ad-hoc peer-to-peer network.

3. A method as claimed in claim 1, wherein:

the gratuitous reply message indicates to the access point a route from the access point to the at least one other node.

4. A method as claimed in claim 1, wherein:

the access point advertisement transmitting step transmits the access point advertisement from the access point to a plurality of said nodes of the network in a broadcast range of the access point;

the first route request message transmitting step transmits a respective said route request message from each of said plurality of nodes to the access point upon their respective receipt of the access point advertisement with desired criteria;

the first reply message transmitting step transmits a reply message from the access point to each of said plurality of nodes upon receipt of the respective route request messages by the access point;

the rebroadcasting step rebroadcasts the access point advertisement from each of said plurality of nodes to respective said other nodes of the network in a respective broadcast range of each of said plurality of nodes;

the second route request message transmitting step transmits a respective said route request message from each respective said other node to the one of said plurality of nodes from which it received the rebroadcast access point advertisement with desired criteria;

the second reply message transmitting step transmits a respective said reply message from each of said plurality of nodes that received a said route request message whose destination only flag is not set to said respective other nodes within their broadcast range, and a respective said gratuitous reply message from said each of said plurality of nodes to the access point, upon their respective receipt of the respective route request messages whose destination only flag is not set; and

the forwarding step forwards those route request messages whose destination only flag is set from said respective nodes at which they were received to the access point.

5. A method as claimed in claim 4, wherein:

each respective said gratuitous reply message indicates to the access point a respective route from the access point to a respective said other node.

6. A method as claimed in claim 1, wherein:

said access point advertisement includes information indicating a number of active nodes in the network associated with the access point.

7. A wireless communication network, comprising:

an access point, adapted to provide access to a portion of the network; and

a plurality of wireless nodes, adapted to communicate with each other and gain access to said portion of said network via the access point;

the access point being further adapted to transmit an access point advertisement to said nodes which are in its broadcast range, the nodes being further adapted to transmit a respective route request message to the access point upon receipt of the access point advertisement with desired criteria, and the access point being further adapted to transmit a respective reply message to the nodes upon receipt of the respective route request messages; and

each of the nodes being adapted to rebroadcast the access point advertisement to other nodes of the network in its respective broadcast range, to receive a respective route request message from each of said other nodes that received the rebroadcast access point advertisement, and, upon receipt of the respective route request messages, to transmit a respective reply message to the respective other nodes and a respective gratuitous reply message to the access point for those of said respective route request messages whose destination only flag is not set, and to instead forward to the access point those of said respective route request messages whose destination only flag is set.

8. A network as claimed in claim 7, wherein:

the network is a wireless ad-hoc peer-to-peer network, and said nodes and said other nodes are adapted to communicate in the wireless ad-hoc peer-to-peer network.

9. A network as claimed in claim 7, wherein:

said access point advertisement includes information indicating a number of active nodes in the network associated with the access point.

10. A method for performing handoff of a mobile subscriber device between first and second wireless routers in a communication network, the method comprising:

when the subscriber device is moving from a coverage area of the first wireless router to a coverage area of the second wireless router, unicast transmitting a routing advertisement, including information identifying the subscriber device, from the subscriber device to the second wireless router;

updating a routing table of the second wireless router in accordance with the information included in the routing advertisement when the second wireless router receives the routing advertisement; and

unicast transmitting another routing advertisement, including information identifying the subscriber device, along a path of communication between the second wireless router and an access point via which the second wireless router gains access to a portion of the network, to inform the access point of the subscriber device.

11. A method as claimed in claim 10, wherein:

the network is a wireless ad-hoc peer-to-peer network, and the first and second wireless routers and the subscriber device communicate in the wireless ad-hoc peer-to-peer network.

12. A method as claimed in claim 10, wherein:

the unicast transmitting step unicast transmits said another routing advertisement along said path which includes a plurality of wireless routers via which said another routing advertisement travels to reach the access point.

13. A wireless communication network, comprising:

a plurality of wireless routers associated with an access point via which the wireless routers gain access to a portion of the network; and

a mobile subscriber device, adapted to communicate with any said wireless router within its broadcast range;

wherein when the subscriber device is moving from a coverage area of a first wireless router to a coverage area of a second wireless router, the subscriber device unicast transmits a routing advertisement, including information identifying the subscriber device, to the second wireless router, and when the second wireless router receives the routing advertisement, the second wireless router updates its routing table in accordance with the information included in the routing advertisement, and unicast transmits another routing advertisement, including information identifying the subscriber device, along a path of communication between the second wireless router and the access point, to inform the access point of the subscriber device.

14. A network as claimed in claim 13, wherein:

the network is a wireless ad-hoc peer-to-peer network, and the wireless routers, the access point and the subscriber device communicate in the wireless ad-hoc peer-to-peer network.

15. A network as claimed in claim 13, wherein:

the second wireless router unicast transmits said another routing advertisement along said path which includes a plurality of wireless routers via which said another routing advertisement travels to reach the access point.

16. A method for performing handoff of a mobile subscriber device between wireless routers in a communication network, the method comprising:

controlling the mobile subscriber device to transmit at a periodic rate a routing request message for an associated access point to the communication network;

receiving the routing request message at one of the wireless routers; and

providing the routing request message from the wireless router at which it was received to the associated access point to inform the associated access point of a route to the mobile subscriber device.

17. A method as claimed in claim 16, wherein:

the periodic rate is based on a speed at which the mobile subscriber device is moving.

18. A method as claimed in claim 16, wherein:

the network is a wireless ad-hoc peer-to-peer network, and the wireless routers, the access point and the subscriber device communicate in the wireless ad-hoc peer-to-peer network.

19. A wireless communication network, comprising:

a plurality of wireless routers associated with an access point via which the wireless routers gain access to a portion of the network; and

a mobile subscriber device, adapted to communicate with any said wireless router within its broadcast range, to transmit at a periodic rate a routing request message for an associated said access point to said any wireless router, which is adapted to provide the routing request message to the associated access point to inform the associated access point of a route to the mobile subscriber device.

20. A wireless communication network as claimed in claim 19, wherein:

the periodic rate is based on a speed at which the mobile subscriber device is moving.

21. A method as claimed in claim 19, wherein:

the network is a wireless ad-hoc peer-to-peer network, and the wireless routers, the access point and the subscriber device communicate in the wireless ad-hoc peer-to-peer network.

22. A method for performing handoff of a mobile subscriber device between wireless routers in a communication network, the method comprising:

controlling the mobile subscriber device to evaluate respective routing metrics associated with the respective wireless routers as the mobile subscriber device is moving; and

controlling the mobile subscriber device to send a routing request message to the wireless router whose respective said routing metrics meet a desired criteria.

23. A method as claimed in claim 22, wherein:

the respective routing metrics including information pertaining to factors which affect an ability of the mobile subscriber device to communicate with its associated access point of the network via a respective said wireless router.

24. A method as claimed in claim 22, wherein:

the network is a wireless ad-hoc peer-to-peer network, and the wireless routers, the access point and the subscriber device communicate in the wireless ad-hoc peer-to-peer network.