Line of sight determination between nodes of a wireless network

• US 20070201411A1
• Filed: 02/27/2006
• Published: 08/30/2007
• Est. Priority Date: 02/27/2006
• Status: Abandoned Application

• Current Assignee: Tropos Networks Incorporated (ABB Limited)
• Original Assignee: Tropos Networks Incorporated (ABB Limited)
• Inventors: Behroozi, Cyrus
• Application Number:
  US11/362,937
• Publication Number:
  US 20070201411A1
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 40/04 based on wireless node resources
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for determining line of sight between nodes of a wireless network is disclosed. The method includes identifying line-of-sight links between nodes within the wireless mesh network, and communicating the line-of-sight links between nodes to the system operator, allowing the system operator to selectively replace non-line-of-sight technology nodes with higher capacity line-of-sight nodes.

Claims

1. A method of allowing a wireless mesh network system operator to improve capacity of a non-line-of-sight technology wireless mesh network, comprising:

deploying the wireless mesh network with access nodes having non-line-of sight technology links;

identifying line-of-sight links between nodes within the wireless mesh network;

communicating the line-of-sight links between nodes to the system operator, allowing the system operator to selectively replace non-line-of-sight technology nodes with higher capacity nodes that include line-of-sight technology.

2. The method of claim 1, wherein identifying line-of-sight links between nodes within the wireless mesh network comprises:

transmitting a signal over a predetermined channel from a first node to a second node;

the second node comparing a signal amplitude of a corresponding received signal with an expected line-of-sight signal amplitude.

3. The method of claim 2, wherein a link between the first node and the second node is designated a line-of-sight link if the signal amplitude of the received signal is within a predetermined margin of the expected line-of-sight signal amplitude.

4. The method of claim 2, wherein the expected line-of-sight signal amplitude is determined by determining a distance between the first node and the second node, and calculating the expected line-of-sight signal amplitude based upon the distance.

5. The method of claim 1, wherein identifying line-of-sight links between nodes within the wireless mesh network comprises:

transmitting a signal over a predetermined channel from a first node to a second node;

the second node comparing a signal delay spread of a corresponding received signal with an expected line-of-sight signal delay spread.

6. The method of claim 1, wherein identifying line-of-sight links between nodes within the wireless mesh network comprises identifying links that maintain line-of-site for a predetermined duration of time.

7. The method of claim 1, wherein identifying line-of-sight links between nodes within the wireless mesh network comprises:

identifying nodes within the mesh network that are in communication with each other;

for each of the identified nodes, transmitting a signal over a predetermined channel from a transmitting node to a receiving node;

each receiving node comparing a signal amplitude of a received signal with an expected line-of-sight signal amplitude;

designating nodes that have a received signal amplitude that is within a predetermined margin of an expected line-of-sight signal amplitude, as line-of-sight nodes.

8. The method of claim 7, wherein a list of line of sight nodes are communicated to the wireless mesh network system operator.

9. The method of claim 7, wherein identifying nodes within the mesh network that are in communication with each other comprises identifying nodes that receive routing packets from another node.

10. The method of claim 1, wherein after upgrading by the system operator, selecting routing paths through the mesh network comprises:

access nodes receiving routing beacons from upstream devices;

each access node selecting an upstream link based on whether the link is a line-of-sight links or a non-line of sight link;

when selecting between similar technology links, each access node selecting the link that provides routing beacons having a highest reception persistence.

11. The method of claim 10, wherein line-of-sight links are given routing path selection preference over non-line-of-sight links.

12. The method of claim 10, wherein the upstream device is at least one of a gateway and an upstream access node.

13. The method of claim 10, wherein the reception persistence is a measure of a number of successfully received routing beacons per unit of time.

14. The method of claim 10, wherein gateways originate and broadcast routing beacons, and access nodes rebroadcast modified routing beacons of selected upstream links.

15. A method of determining which links of a mesh network can be upgrade to a higher capacity link, comprising:

identifying links between access nodes of the mesh network;

determining which of the links are line-of-sight links;

providing a network manager with information regarding the links that are line-of-sight links.

16. The method of claim 15, wherein identifying links between access nodes of the mesh network comprises determining which non-line-of-sight technology links of the access nodes allow transmission of packets.

17. The method of claim 15, wherein determining which of the links are line-of-sight links comprises comparing a received signal power with an expected line-of-sight signal power.

18. The method of claim 17 wherein the expected line-of-sight signal power is determined by knowing distances between the access nodes.

19. The method of claim 15, wherein determining which of the links are line-of-sight links comprises:

for each of the identified links, transmitting a signal over a predetermined channel from a transmitting node to a receiving node;

each receiving node comparing a signal amplitude of a received signal with an expected line-of-sight signal amplitude;

designating nodes that have a received signal amplitude that is within a predetermined margin of an expected line-of-sight signal amplitude, as line-of-sight nodes.

20. A wireless mesh network comprising:

means for identifying nodes within the mesh network that are in communication with each other;

means for transmitting a signal over a predetermined channel from a transmitting node to a receiving node for each of the identified nodes;

means for comparing a signal amplitude of a received signal with an expected line-of-sight signal amplitude for each receiving node;

means for designating nodes that have a received signal amplitude that is within a predetermined margin of an expected line-of-sight signal amplitude, as line-of-sight nodes;

means for communicating the line-of-sight links to a network manager.