Method For Fast Synchronization and Frequency Hop Sequence Detection in Wireless Sensor Networks

• US 20100034239A1
• Filed: 08/08/2008
• Published: 02/11/2010
• Est. Priority Date: 08/08/2008
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Keshavarzian, Abtin, Manjeshwar, Arati
• Granted Patent: US 8,054,864 B2
• Time in Patent Office: Days
• US Class Current: 375/134
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04B 2001/71563 Acquisition
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA

Abstract

A method of synchronizing wireless devices includes establishing a recurring sequence of frequency channels at which the wireless devices are to communicate. The frequency channels are divided into a plurality of groups. Synchronization information is transmitted at a respective first frequency channel in each of the groups of frequency channels during a first sampling time period. One of the groups of frequency channels is selected. A wireless device is used to sample each of the frequency channels in the selected group during the first sampling time period. Non-synchronization information is transmitted after the first sampling time period. Synchronization information is transmitted at a next respective frequency channel in each of the groups of frequency channels during a next sampling time period. The next sampling time period occurs after the transmitting of the non-synchronization information.

Claims

1. A method of synchronizing wireless devices, the method comprising the steps of:

establishing a recurring sequence of frequency channels at which the wireless devices are to communicate;

dividing the frequency channels into a plurality of groups;

transmitting synchronization information at a respective first frequency channel in each of the groups of frequency channels during a first sampling time period;

selecting one of the groups of frequency channels;

using one of the wireless devices to sample each of the frequency channels in the selected group during the first sampling time period;

transmitting non-synchronization information after the first sampling time period; and

transmitting synchronization information at a next respective frequency channel in each of the groups of frequency channels during a next sampling time period, the next sampling time period occurring after the transmitting of the non-synchronization information.

2. The method of claim 1 comprising the further step of transmitting non-synchronization information after the next sampling time period.

3. The method of claim 2 wherein the steps of transmitting synchronization information at a next respective frequency channel and transmitting the non-synchronization information are repeated until synchronization information has been transmitted in each of the frequency channels in each of the groups of frequency channels.

4. The method of claim 3 wherein, after synchronization information has been transmitted in each of the frequency channels in each of the groups of frequency channels, the transmitting steps are repeated until synchronization information has again been transmitted in each of the frequency channels in each of the groups of frequency channels.

5. The method of claim 4, comprising the further steps of:

selecting an other one of the groups of frequency channels; and

using an other one of the wireless devices to sample each of the frequency channels in the selected other group during one of the sampling time periods.

6. The method of claim 1 wherein the frequency channels are in at least one of frequency bands 902 to 928 MHz and 2400 to 2483.4 MHz.

7. The method of claim 1 wherein the synchronization information comprises a time period and a frequency channel associated with transmission of non-synchronization information.

8. A method of synchronizing wireless devices, the method comprising the steps of:

establishing a recurring sequence of frequency channels at which the wireless devices are to communicate;

dividing the frequency channels into a plurality of groups;

transmitting synchronization information at a respective first frequency channel in each of the groups of frequency channels during a first sampling time period;

using a wireless device to select one of the groups of frequency channels;

using one of the wireless devices to sample each of the frequency channels in the selected group for the synchronization information, the sampling occurring during the first sampling time period;

transmitting non-synchronization information after the first sampling time period;

transmitting synchronization information at a next respective frequency channel in each of the groups of frequency channels during a next sampling time period, the next sampling time period occurring after the transmitting of the non-synchronization information;

transmitting non-synchronization information after the next sampling period; and

repeating the steps of transmitting synchronization information at a next respective frequency channel and transmitting the non-synchronization information until synchronization information has been transmitted in each of the frequency channels in each of the groups of frequency channels.

9. The method of claim 8 comprising the further step of adding a preamble to the synchronization information, a time duration of the preamble being approximately equal to an amount of time needed to sample each of the frequency channels in the selected group.

10. The method of claim 8 comprising the further step of informing each of the wireless devices of the recurring sequence of frequency channels at which the wireless devices are to communicate.

11. The method of claim 8 wherein, after synchronization information has been transmitted in each frequency channel in each of the groups of frequency channels, the transmitting steps are repeated until synchronization information has again been transmitted in each of the frequency channels in each of the groups of frequency channels.

12. The method of claim 11, comprising the further steps of:

selecting an other one of the groups of frequency channels; and

using an other wireless device to sample each of the frequency channels in the selected other group during one of the first sampling periods.

13. The method of claim 8 wherein the frequency channels are in at least one of frequency bands 902 to 928 MHz and 2400 to 2483.4 MHz.

14. The method of claim 8 wherein the synchronization information comprises a time period and a frequency channel associated with transmission of non-synchronization information.

15. A method of synchronizing wireless devices, the method comprising the steps of:

informing each of the wireless devices of a frequency channel hop sequence at which non-synchronization information is to be transmitted;

transmitting synchronization information sequentially to each of a plurality of frequency channels in a first subset of the frequency channels included in the hop sequence;

using one of the wireless devices to sample each of the frequency channels in a second subset of the frequency channels, the second subset including one frequency channel included in the first subset and at least one frequency channel omitted from the first subset;

transmitting non-synchronization information after the sampling of the frequency channels in the second subset; and

transmitting synchronization information sequentially to each of a plurality of frequency channels in a third subset of the frequency channels, the third subset including one of the frequency channels in the second subset and none of the frequency channels in the first subset.

16. The method of claim 15, wherein the transmitting of the synchronization information to the third subset of frequency channels occurs after the transmitting of the non-synchronization information.

17. The method of claim 15 comprising the further step of transmitting non-synchronization information after the transmitting of the synchronization information to the third subset of frequency channels.

18. The method of claim 17 wherein steps of transmitting synchronization information and subsequently transmitting non-synchronization information are repeated until synchronization information has been transmitted in each of the frequency channels in the hop sequence.

19. The method of claim 18 wherein, after synchronization information has been transmitted in each of the frequency channels in the hop sequence, the transmitting steps are repeated until synchronization information has again been transmitted in each of the frequency channels in the hop sequence.

20. The method of claim 15 wherein the synchronization information comprises a time period and a frequency channel associated with transmission of non-synchronization information.