Topology scanning in a multi-hop wireless network
In one embodiment, a method includes, by first network node of a multi-hop wireless network, transmitting one or more scan-request messages during a topology scanning, where the topology scanning is performed for a predetermined number of scan cycles, and where the first network node is connected to a central controller of the multi-hop wireless network, receiving a scan-response message sent using a transmission beam j by a second network node, where the second network node is unconnected to the central controller, storing information associated with the second network node, where the information comprises an indication that beam i is a beam for communications at the first network node, an indication that beam j is a beam for communications at the second network node, an identifier for the second network node, and the geo-location information associated with the second network node, and sending a network-ignition-request message to the second network node.
1. A method comprising:
by the first network node of a multi-hop wireless network, transmitting one or more scan-request messages during a topology scanning, wherein:
the topology scanning is performed for a particular number of scan cycles;
each scan cycle comprises n beamforming windows;
n corresponds to a predefined number of beams;
each beam corresponds to a predetermined configuration of beamforming weights of an array of beamforming antennae;
the first network node is connected to a central controller of the multi-hop wireless network;
the one or more scan-request messages are transmitted using a transmission beam i; and
each of the one or more scan-request messages comprises:
a broadcast address as a scan-request destination address; and
a first identifier identifying the first network node as a scan-request source address;
by the first network node, receiving a scan-response message sent using a transmission beam j by a second network node, wherein:
the second network node is unconnected to the central controller; and
the scan-response message comprises:
the first identifier as a scan-response destination address;
a second identifier identifying the second network node as a scan-response source address; and
one or more identifiers of one or more network nodes collocated with the second network node;
by the first network node, storing information associated with the second network node, wherein the information comprises:
an indication that beam i is a beam for communications at the first network node;
an indication that beam j is a beam for communications at the second network node;
the second identifier; and
the identifiers of the network nodes collocated with the second network node; and
by the first network node, sending a network-ignition-request message to the second network node.
2. The method of claim 1 , wherein the topology scanning is triggered when the first network node is configured as an initiator by the central controller.
3. The method of claim 1 , wherein the topology scanning is triggered when the first network node receives an explicit triggering message from the central controller.
4. The method of claim 1 , wherein each network node of the multi-hop wireless network comprises a plurality of arrays of beamforming antennae that are each operable to support a wireless connection between the network node and another network node of the multi-hop wireless network.
5. The method of claim 1 , wherein a beamforming window comprises n beamforming frames, and wherein a beamforming frame comprises a plurality of transmission slots and a plurality of reception slots.
6. The method of claim 5 , wherein the first network node transmits a scan-request message using the transmission beam i at each beamforming frame of beamforming window i in each scan cycle.
7. The method of claim 6 , wherein the first network node listens to signals using a reception beam i at each beamforming frame of beamforming window i+N in each scan cycle, wherein N is a predetermined constant number, and wherein the scan-response message received in beamforming window i+N is a response to one of the one or more scan-request messages sent in beamforming window i.
8. The method of claim 1 , wherein the first identifier is a media access control (MAC) address associated with the first network node.
9. The method of claim 1 , wherein the second identifier is a MAC address associated with the second network node.
10. The method of claim 1 , wherein the scan-response message further comprises geo-location information associated with the second network node, and wherein the geo-location information comprises global positioning system (GPS) coordinates.
11. The method of claim 5 , further comprising sending a scan-acknowledgement message to the second network node using transmission beam i.
12. A method comprising:
by a second network node of a multi-hop wireless network, acquiring, from a GPS module connected to the second network node, geo-location information, frequency and timing information, wherein:
the second network node is in a responder mode because the second network node is unconnected to a central controller of the multi-hop wireless network;
the second network node synchronizes to beamforming cycles based on the acquired frequency and timing information;
a beamforming cycle comprises n beamforming windows;
n corresponds to a predefined number of beams;
each beam corresponds to a predetermined configuration of beamforming weights of an array of beamforming antennae;
a beamforming window comprises n beamforming frames; and
the second node, while being in the responder mode, listens to signals using reception beam j at beamforming frame j of each beamforming window;
by the second network node, receiving, at beamforming frame j of beamforming window i, from a first network node, a scan-request message comprising a broadcast address as a scan-request destination address; and
by the second network node, sending, at a randomly selected beamforming frame of beamforming window i+N, a scan-response message using a transmission beam j, wherein N is a predetermined constant number.
13. The method of claim 12 , wherein, if the second network node receives a plurality of scan-request messages at more than one beamforming frames of the beamforming window i, the beamforming frame j is a beamforming frame associated with a highest reception signal strength.
14. The method of claim 12 , wherein the second network node sends the scan-response message at a randomly selected beamforming frame to reduce a probability of collisions.
15. The method of claim 12 , further comprising:
receiving a scan-acknowledgement message from the first network node; and
storing information associated with the first network node, wherein the information comprises:
an indication that beam i is a beam for communications at the first network node; and
an indication that beam j is a beam for communications at the second network node.
16. The method of claim 15 , wherein the second computing device ignores any scan-request message from the first network node received in beamforming window i of any following beamforming cycle.
17. A first network node comprising: one or more processors; and a non-transitory memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to:
transmit one or more scan-request messages during a topology scanning, wherein:
the topology scanning is performed for a particular number of scan cycles;
each scan cycle comprises n beamforming windows;
n corresponds to a predefined number of beams;
each beam corresponds to a predetermined configuration of beamforming weights of an array of beamforming antennae;
the first network node is connected to a central controller of the multi-hop wireless network;
the one or more scan-request messages are transmitted using a transmission beam i; and
each of the one or more scan-request messages comprises:
a broadcast address as a scan-request destination address; and
a first identifier identifying the first network node as a scan-request source address;
receive a scan-response message sent using a transmission beam j by a second network node, wherein:
the second network node is unconnected to the central controller; and
the scan-response message comprises:
the first identifier as a scan-response destination address;
a second identifier identifying the second network node as a scan-response source address; and
one or more identifiers of one or more network nodes collocated with the second network node;
store information associated with the second network node, wherein the information comprises:
an indication that beam i is a beam for communications at the first network node;
an indication that beam j is a beam for communications at the second network node;
the second identifier; and
the identifiers of the network nodes collocated with the second network node; and
send a network-ignition-request message to the second network node.
18. The first network node of claim 17 , wherein the topology scanning is triggered when the first network node is configured as an initiator by the central controller.
19. The first network node of claim 17 , wherein the topology scanning is triggered when the first network node receives an explicit triggering message from the central controller.
20. The first network node of claim 17 , wherein each network node of the multi-hop wireless network comprises a plurality of arrays of beamforming antennae that are each operable to support a wireless connection between the network node and another network node of the multi-hop wireless network.