COMMUNICATING TIMING INFORMATION FOR A NEXT DIO TRANSMISSION

• US 20190182774A1
• Filed: 12/07/2017
• Published: 06/13/2019
• Est. Priority Date: 12/07/2017
• Status: Active Grant

• Current Assignee: Landis+Gyr Technology, Inc. (Landis+Gyr Group AG)
• Original Assignee: Landis+Gyr Innovations Incorporated (Landis+Gyr Group AG)
• Inventors: Jain, Saurabh, Singh, Shobhit Kumar
• Granted Patent: US 10,448,335 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• 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 network using a routing protocol for low-power and lossy networks (“RPL”) can provide timing information for a next destination oriented directed acyclic graph (“DODAG”) information object (“DIO”) packet by including DIO timing information in an RPL packet or a beacon. When a low energy node receives the RPL packet, it may use the DIO timing information to determine a wake time which corresponds to the timing of the next DIO packet. The low energy node may enter a sleep state after determining the wake time and remain in the sleep state until the wake time when it enters an active state and listens for the next DIO packet. Alternatively, DIO slots in a DIO slot frame may be allocated for communicating DIO packets.

Claims

1. A network using a routing protocol for low-power and lossy networks (“

RPL”

), the network comprising;

a first node including a trickle timer for determining a plurality of transmission intervals for a plurality of destination oriented directed acyclic graph (“

DODAG”

) information object (“

DIO”

) packets, wherein each transmission interval is based on a current state of the network, wherein the first node is operable to transmit a first DIO packet based upon the trickle timer and the first DIO packet includes DIO timing information for a second DIO packet; and

a second node communicatively coupled to the first node via the network, the second node operable to;

receive the first DIO packet from the first node at a first time;

using the DIO timing information in the first DIO packet, determine a second time corresponding to the second DIO packet;

enter a sleep state subsequent to determining the second time, the second node having reduced power consumption while in the sleep state as compared to an active state;

enter the active state from the sleep state prior to the second time; and

listen for the second DIO packet from the first node at the second time.

2. The network of claim 1, wherein the second node is further operable to:

receive the second DIO packet from the first node, wherein the second DIO packet includes DIO timing information for a third DIO packet;

determine a third time based on the DIO timing information in the second DIO packet; and

enter the sleep state subsequent to determining the third time; and

enter the active state from the sleep state prior to the third time,

wherein a length of the sleep state between the first time and the second time is different than a length of the sleep state between the second time and the third time.

3. The network of claim 1, wherein the second node is further operable to:

when the second node fails to receive the second DIO packet at the second time, continue to listen for the second DIO packet for a predetermined amount of time; and

when the second node fails to receive the second DIO packet after the predetermined amount of time, then listen for a beacon.

4. The network of claim 1, wherein the first DIO packet includes a DIO timing information option that specifies a value for an amount of time and a value for a type of time.

5. The network of claim 4, wherein the first node is a parent node for the second node, and the second node is further operable to:

after the second node receives the second DIO packet, analyze a DIO rank indicator in the second DIO packet;

when the DIO rank indicator indicates that the first node is unjoined from the network, then analyze the value for the amount of time in the DIO timing information option; and

when the value for the amount of time in the DIO timing information option is a predetermined value, then search for a new parent node.

6. The network of claim 1, further comprising:

a router node communicatively coupled to the first node via the network, wherein the router node is operable to;

receive the first DIO packet from the first node;

using the DIO timing information in the first DIO packet, determine a second time corresponding to the second DIO packet;

when the router node fails to receive the second DIO packet, continue to listen for the second DIO packet for a predetermined amount of time; and

when the router node fails to receive the second DIO packet after the predetermined amount of time, then send a DODAG Information Solicitation (“

DIS”

) to the first node.

7. The network of claim 4, further comprising:

a router node communicatively coupled to the first node via the network, wherein the first node is a parent node for the router node, the router node operable to;

receive the second DIO packet;

after receiving the second DIO packet, analyze a DIO rank indicator in the second DIO packet;

when the DIO rank indicator indicates that the first node is unjoined from the network, then search for a new parent node; and

when the DIO rank indicator indicates that the first node is joined to the network, then using DIO timing information in the second DIO packet to determine a third time corresponding to a third DIO packet.

8. The network of claim 3, wherein the second node is further operable to:

when the second node fails to receive the beacon prior to expiration of an EBR (enhanced beacon request) time, transmit an EBR that includes a request for DIO timing information.

9. The network of claim 1, wherein the first node is further operable to:

transmit a beacon that includes a DIO timing information element for a subsequent DIO packet.

10. The network of claim 9, wherein the second node is further operable to:

receive the beacon that includes the DIO timing information element for a subsequent DIO packet.

11. The network of claim 1, wherein the first node is further operable to:

receive an enhanced beacon request (“

EBR”

) that includes a request for a DIO timing information element.

12. A method for a node communicatively coupled to a network using a routing protocol for low-power and lossy networks (“

RPL”

), the method comprising;

using a trickle timer to determine a plurality of transmission intervals for a plurality of destination oriented directed acyclic graph (“

DODAG”

) information object (“

DIO”

) packets, wherein each transmission interval is based on a current state of the network;

determine DIO timing information for a second DIO packet;

transmitting a first DIO packet based on the trickle timer, wherein the first DIO packet includes the DIO timing information for the second DIO packet and DIO rank information for the node; and

after the node is unjoined from the network, transmitting a third DIO packet that includes DIO timing information for a fourth DIO packet and DIO rank information indicating that the node is unjoined from the network.

13. The method of claim 12, wherein a DIO timing option in the first DIO packet specifies a value for an amount of time and a value for a type of time.

14. The method of claim 13, wherein so long as the node remains unjoined from the network, transmitting additional DIO packets, each additional DIO packet includes DIO timing information for a next additional DIO packet and the DIO rank information indicating that the node is unjoined from the network.

15. The method of claim 14, wherein after the node remains unjoined for a predetermined amount of time, the additional DIO packet includes DIO timing information with the value for the amount of time set to a predetermined value.

16. The method of claim 13, wherein the value for the amount of time corresponds to an absolute slot number when the value for the type of time corresponds to a slot number.

17. The method of claim 13, wherein the value for the amount of time corresponds to a time interval when the value for the type of time corresponds to a relative time.

18. The method of claim 12, wherein transmitting a first DIO packet based on the trickle timer comprises transmitting the first DIO packet during an allocated DIO time slot.

19. A method for a node communicatively coupled to a network using a routing protocol for low-power and lossy networks (“

RPL”

), the method comprising;

receiving DIO slot allocation information from a coordinator node, wherein the DIO slot allocation information allocates a main DIO slot and at least one additional DIO slot per DIO slot frame to the node;

providing a trickle timer for determining a plurality of transmission intervals for a plurality of DIO packets wherein each transmission interval is based on a current state of the network;

determining DIO timing information for a second DIO packet, wherein the DIO timing information for the second DIO packet indicates a transmission time for the second DIO packet;

transmitting a first DIO packet, wherein the first DIO packet includes DIO timing information for the second DIO packet;

when the DIO timing information for the second DIO packet is greater than a duration of the DIO slot frame, then transmitting the second DIO packet during a next main DIO slot following the transmission time for the second DIO packet; and

when the DIO timing information for the second DIO packet is less than the duration of the DIO slot frame, then transmitting the second DIO packet during a next allocated DIO slot following the transmission time for the second DIO packet.

20. The method of claim 19, wherein a length of the DIO slot frame is based on a minimum trickle interval for the trickle timer.

21. The method of claim 19, further comprising:

resetting the trickle timer; and

in response to resetting the trickle timer, discontinuing transmissions of the DIO packets using the transmission intervals, determining a new transmission schedule, and transmitting information corresponding to the new transmission schedule in DIO timing information for a third DIO packet.

22. The method of claim 19, further comprising:

generating the first DIO packet at a first layer in a protocol stack of the node; and

sending the first DIO packet and DIO slot information to a second layer in the protocol stack, wherein the DIO slot information indicates whether to transmit the first DIO packet during the next main DIO slot or the next DIO slot.