POWER CONSERVATION AND LATENCY MINIMIZATION IN FREQUENCY HOPPING COMMUNICATION NETWORKS

• US 20130016759A1
• Filed: 07/12/2011
• Published: 01/17/2013
• Est. Priority Date: 07/12/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Systems, Inc.
• Inventors: Hui, Jonathan W., Hong, Wei, Woo, Lik Chuen Alec
• Granted Patent: US 9,450,642 B2
• Time in Patent Office: Days
• US Class Current: 375/135
• CPC Class Codes: H04B 1/713 using frequency hopping

Abstract

In one embodiment, a communication device samples a particular frequency hopping sequence during only a particular specified sub-timeslot of a timeslot. If a transmission energy is not detected during the specified sub-timeslot, the device turns off its receiver for a remainder of the timeslot. Otherwise, it continues to sample the particular frequency hopping sequence for at least one or more additional sub-timeslots of the remainder of the timeslot. In another embodiment, a communication device determines whether a neighboring communication device is operating in a first mode or a second mode. If in the second mode, it transmits a transmission to the neighboring communication device starting at any sub-timeslot of the plurality of sub-timeslots. If in the first mode, it transmits the transmission to the neighboring communication device while ensuring that the transmission is actively energized during a particular specified sub-timeslot.

Claims

1. A method, comprising:

operating a communication device according to a particular frequency hopping sequence in a communication network, the particular frequency hopping sequence having a plurality of timeslots each corresponding to a particular frequency within the frequency hopping sequence, each timeslot divided into a plurality of sub-timeslots; and

operating the communication device in a first mode, wherein the first mode comprises;

sampling the particular frequency hopping sequence by a receiver of the communication device during only a particular specified sub-timeslot of a timeslot;

detecting whether a transmission energy is detected during the specified sub-timeslot;

in response to detecting that there is no transmission energy during the specified sub-timeslot, turning off the receiver for a remainder of the timeslot; and

is in response to detecting that there is transmission energy during the specified sub-timeslot, continuing to sample the particular frequency hopping sequence for at least one or more additional sub-timeslots of the remainder of the timeslot.

2. The method as in claim 1, wherein sampling during only the specified sub-timeslot comprises sampling an initial sub-timeslot of each timeslot of the particular frequency hopping sequence.

3. The method as in claim 1, wherein sampling during only the specified sub-timeslot comprises sampling the specified sub-timeslot of only certain timeslots of the particular frequency hopping sequence.

4. The method as in claim 1, wherein continuing to sample the particular frequency hopping sequence for at least one or more additional sub-timeslots of the remainder of the timeslot comprises:

determining whether the transmission energy is from a transmission meant for the communication device;

keeping the receiver on for at least a duration of the transmission in response to the transmission being meant for the communication device; and

turning off the receiver in response to the transmission not being meant for the communication device.

5. The method as in claim 1, further comprising:

selecting operation of the communication device between the first mode and a second mode; and

operating the communication device in the second mode, wherein the second mode comprises;

sampling the particular frequency hopping sequence by the receiver of the communication device during all non-transmitting sub-timeslots of the particular frequency hopping sequence.

6. The method as in claim 5, wherein selecting comprises:

selecting the first mode in response to a power reduction at the communication device.

7. The method as in claim 1, further comprising:

informing one or more neighboring devices that the communication device is operating according to the first mode.

8. The method as in claim 7, wherein informing comprises:

including an indication within a message selected from a group consisting of;

an explicit indication message having the indication;

an outgoing message having the indication piggybacked therein; and

an outgoing acknowledgement message having the indication piggybacked therein.

9. A method, comprising:

operating a communication device according to a particular frequency hopping sequence in a communication network, the particular frequency hopping sequence having a plurality of timeslots each corresponding to a particular frequency within the frequency hopping sequence, each timeslot divided into a plurality of sub-timeslots; and

determining whether a neighboring communication device is operating in a first mode or a second mode;

in response to determining that the neighboring communication device is operating in the second mode, transmitting a transmission to the neighboring communication device starting at any sub-timeslot of the plurality of sub-timeslots; and

in response to determining that the neighboring communication device is operating in the first mode, transmitting the transmission to the neighboring communication device while ensuring that the transmission is actively energized during a particular specified sub-timeslot.

10. The method as in claim 9, wherein the specified sub-timeslot is an initial sub-timeslot of a particular timeslot.

11. The method as in claim 9, wherein determining whether the neighboring communication device is operating in the first mode or the second mode comprises:

assuming that the neighboring communication device is operating in the second mode as a default mode.

12. The method as in claim 11, wherein determining that the neighboring communication device is operating in the first mode comprises:

transmitting the transmission to the neighboring communication device starting at any sub-timeslot of the plurality of sub-timeslots;

determining that no acknowledgement for the transmission is received from the neighboring communication device; and

assuming that the neighboring communication device is operating in the first mode based on determining that no acknowledgement for the transmission is received from the neighboring communication device.

13. The method as in claim 12, further comprising:

determining that no acknowledgement for the transmission is received from the neighboring communication device in response to transmitting the transmission to the neighboring communication device while ensuring that the transmission is actively energized during a particular specified sub-timeslot according to the first mode; and

in response, declaring the neighboring communication device unreachable.

14. The method as in claim 9, wherein determining that the neighboring communication device is operating in the first mode comprises:

determining that the neighboring communication device is operating in the first mode in response to receiving an indication within a message received from the neighboring communication device that informs the communication device that the neighboring communication device is operating according to the first mode.

15. The method as in claim 9, wherein ensuring that the transmission is actively energized during a particular specified sub-timeslot comprises:

transmitting one or more contiguous wake-up transmissions prior to the specified sub-timeslot and during the specified sub-timeslot to account for potential clock-drift of the neighboring communication device.

16. An apparatus, comprising:

a processor; and

a receiver configured to communicate in a communication network according to a particular frequency hopping sequence, the particular frequency hopping sequence having a plurality of timeslots each corresponding to a particular frequency within the frequency hopping sequence, each timeslot divided into a plurality of sub-timeslots according to a first mode;

wherein the receiver is configured to operate in a first mode, wherein the receiver and processor when operated in the first mode are operable to;

sample the particular frequency hopping sequence during only a particular specified sub-timeslot of a timeslot;

detect whether a transmission energy is detected during the specified sub-timeslot; and

in response to detecting that there is no transmission energy during the specified sub-timeslot, turn off the receiver for a remainder of the timeslot; and

in response to detecting that there is transmission energy during the specified sub-timeslot, continue to sample the particular frequency hopping sequence for at least one or more additional sub-timeslots of the remainder of the timeslot.

17. The apparatus as in claim 16, wherein the receiver and processor, when operated in the first mode to sample during only the specified sub-timeslot, are further operable to:

sample an initial sub-timeslot of each timeslot of the particular frequency hopping sequence.

18. The apparatus as in claim 16, wherein the receiver and processor, when operated in the first mode to continue to sample the particular frequency hopping sequence for at least one or more additional sub-timeslots of the remainder of the timeslot, are further operable to:

determine whether the transmission energy is from a transmission meant for the receiver;

keep the receiver on for at least a duration of the transmission in response to the transmission being meant for the receiver; and

turn off the receiver in response to the transmission not being meant for the receiver.

19. The apparatus as in claim 16, wherein the receiver and processor are further operable to:

select operation of the receiver between the first mode and a second mode; and

wherein the receiver and processor when operated in the second mode are operable to;

sample the particular frequency hopping sequence by the receiver during all non-transmitting sub-timeslots of the particular frequency hopping sequence.

20. The apparatus as in claim 19, wherein the receiver and processor, when operable to select, are further operable to:

select the first mode in response to a power reduction at the apparatus.

21. An apparatus, comprising:

a processor; and

a transmitter configured to communicate in a communication network according to a particular frequency hopping sequence, the particular frequency hopping sequence having a plurality of timeslots each corresponding to a particular frequency within the frequency hopping sequence, each timeslot divided into a plurality of sub-timeslots according to a first mode;

wherein the transmitter and processor when operated are operable to;

determine whether a neighboring communication device is operating in a first mode or a second mode;

in response to determining that the neighboring communication device is operating in the second mode, transmit a transmission to the neighboring communication device starting at any sub-timeslot of the plurality of sub-timeslots; and

in response to determining that the neighboring communication device is operating in the first mode, transmit the transmission to the neighboring communication device while ensuring that the transmission is actively energized during a particular specified sub-timeslot.

22. The apparatus as in claim 21, wherein the transmitter and processor, when operable to determine whether the neighboring communication device is operating in the first mode or the second mode, are further operable to:

assume that the neighboring communication device is operating in the second mode as a default mode.

23. The apparatus as in claim 22, wherein the transmitter and processor, when operable to determine whether the neighboring communication device is operating in the first mode or the second mode, are further operable to:

transmit the transmission to the neighboring communication device starting at any sub-timeslot of the plurality of sub-timeslots;

determine that no acknowledgement for the transmission is received from the neighboring communication device; and

assume that the neighboring communication device is operating in the first mode based on determining that no acknowledgement for the transmission is received from the neighboring communication device; and

declare the neighboring communication device unreachable in response to determining that no acknowledgement for the transmission is received from the neighboring communication device in response to transmitting the transmission to the neighboring communication device while ensuring that the transmission is actively is energized during a particular specified sub-timeslot according to the first mode.

24. The apparatus as in claim 21, wherein the transmitter and processor, when operable to determine that the neighboring communication device is operating in the first mode, are further operable to:

determine that the neighboring communication device is operating in the first mode in response to an indication within a message received from the neighboring communication device that informs the apparatus that the neighboring communication device is operating according to the first mode.

25. The apparatus as in claim 21, wherein the transmitter and processor, when operable to ensure that the transmission is actively energized during a particular specified sub-timeslot, are further operable to:

transmit one or more contiguous wake-up transmissions prior to the specified sub-timeslot and during the specified sub-timeslot to account for potential clock-drift of the neighboring communication device.