Bluetooth scan modes

• US 8,649,734 B1
• Filed: 09/05/2012
• Issued: 02/11/2014
• Est. Priority Date: 08/13/2007
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Lin, Yui, Tse, Lawrence, Leong, Poh Boon, Tsai, Minko, Mack, Robert, Hsu, Yungping
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US13/604,563
• Time in Patent Office: 524 Days
• Field of Search: 455/41.2, 455/574, 455/343.1, 455/343.2, 455/343.5, 455/522, 455/434, 455/454
• US Class Current: 455/41.2
• CPC Class Codes: H03J 1/0091 provided with means for scanning over a band of frequencies H03J1/0058 takes precedence
• CPC Class Codes: H04B 7/2612 Arrangements for wireless medium access control, e.g. by allocating physical layer transmission capacity H04B7/2615 - H04B7/2643 take precedence; provision for broadband connection H04Q11/0478

Abstract

Different scan modes are provided for Bluetooth devices. In at least some embodiments, a narrowband scanning mode looks for signal energy on individual transmission frequencies at a time. By looking for signal energy rather than decoding transmitted packets, at least some of the components in a Bluetooth device can remain in an idle or rest state. A midband scanning mode looks for signal energy across multiple different frequencies at a time. Again, by looking for signal energy across multiple different frequencies rather than decoding transmitted packets, at least some of the components in a Bluetooth device can remain in an idle or rest state. A wideband scanning mode looks for signal energies across all relevant frequencies at a time. At least some embodiments enable a Bluetooth device to switch between scanning modes.

Claims

1. A method comprising:

initiating a scan mode in a Bluetooth slave device, the scan mode being one other than a full receive mode;

receiving a signal over one or more Bluetooth frequencies;

ascertaining whether an energy pattern corresponding to a Bluetooth master device is detected within the received signal, the receiving and ascertaining performed when a medium access control component (MAC) of the Bluetooth slave device is in an idle state; and

if the energy pattern corresponding to a Bluetooth master device is detected, entering the full receive mode.

2. The method of claim 1, wherein receiving the signal receives, over a period of time, energy from multiple transmissions.

3. The method of claim 2, wherein the period of time corresponds to a full Bluetooth frame or a portion of a Bluetooth frame.

4. The method of claim 2, further comprising building, based on the energy of the multiple transmissions, a histogram useful to detect the energy pattern that corresponds to the Bluetooth master device.

5. The method of claim 4, wherein building the histogram includes storing information associated with the energy of the multiple transmissions in a memory element or an accumulator.

6. The method of claim 1, wherein the receiving and ascertaining are performed when a digital signal processor (DSP) and an analog-to-digital converter of the Bluetooth slave device are idle.

7. The method of claim 6, wherein the full receive mode is entered responsive to generating an interrupt signal that wakes up one or more idle components of the Bluetooth slave device.

8. The method of claim 7, wherein the interrupt signal wakes up the MAC, the DSP, or the analog-to-digital converter of the Bluetooth slave device.

9. A Bluetooth device comprising circuitry configured to:

initiate a scan mode of the Bluetooth device, the scan mode being one other than a full receive mode;

receive, while the Bluetooth device is in the scan mode, a signal over one or more Bluetooth frequencies;

ascertain whether an energy pattern corresponding to a Bluetooth master device is detected within the received signal, the receiving and ascertaining performed when a medium access control component (MAC) of the Bluetooth device is in an idle state; and

if the energy pattern corresponding to the Bluetooth master device is detected, enter the full receive mode.

10. The Bluetooth device of claim 9, wherein the energy pattern corresponding to the Bluetooth master device includes one or more energy receptions having a duration of approximately 68 microseconds.

11. The Bluetooth device of claim 10, wherein the energy pattern corresponding to the Bluetooth device master includes intervals between the energy receptions of approximately 312 microseconds.

12. The Bluetooth device of claim 9, wherein the received signal includes energy from multiple transmissions received over a same frequency.

13. The Bluetooth device of claim 9, wherein the circuitry is configured to enter the full receive mode by generating an interrupt signal that wakes up one or more idle components on the Bluetooth device.

14. The Bluetooth device of claim 13, wherein the interrupt signal wakes up the MAC, a digital signal processor (DSP), or an analog-to-digital converter of the Bluetooth device.

15. A method comprising:

initiating a scan mode in a Bluetooth slave device, the scan mode not a full receive mode;

receiving a signal over one or more Bluetooth frequencies;

ascertaining whether an energy pattern of the received signal exceeds a first threshold indicating a presence of a Bluetooth master device or a second threshold indicating noise in one or more of the Bluetooth frequencies, the receiving and ascertaining performed when a medium access control component (MAC) of the Bluetooth slave device is in an idle state; and

if the energy pattern exceeds the first threshold, entering the full receive mode;

or

if the energy pattern exceeds the second threshold, entering another scan mode, the other scan mode not the full receive mode.

16. The method of claim 15, wherein the scan mode is a wide-band scan mode and the other scan mode is a narrow-band or medium-band scan mode.

17. The method of claim 15, further comprising waking up the MAC of the Bluetooth device when entering the full receive mode or the other scan mode.

18. The method of claim 15, wherein the scan mode scans approximately 80 MHz of bandwidth.

19. The Bluetooth device of claim 15, wherein the scan mode is implemented using a peak detector for energy detection.

20. The Bluetooth device of claim 15, further comprising building a histogram based on energy of the received signal to provide the energy pattern useful to perform the ascertaining.