Adjustment of period of real-time slow drift correction of alignment of handset's local oscillator for a cordless telephone

• US 20040137962A1
• Filed: 01/08/2004
• Published: 07/15/2004
• Est. Priority Date: 11/23/1999
• Status: Active Grant

• Current Assignee: Auctnyc 7 LLC (Intellectual Ventures LLC)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Mooney, Philip D., Cannon, Joseph M.
• Granted Patent: US 6,925,314 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus to perform a real-time drift correction of a remote handset'"'"'s local oscillator in a digital cordless telephone. The remote handset begins in a standby (sniff) mode. The remote handset periodically wakes from a sleep mode and goes into a normal link verification mode. Once in the link verification mode, the remote handset enters a time division duplexing (TDD) mode and attempts to establish a link with a base unit based on the timing of the TDD data frame. After the remote handset establishes a link with the base unit, the remote handset requests a security word from the base unit. Upon receiving the requested security word, the remote handset determines if the requested security word matches a security word of the remote handset. The remote handset implements a software frequency adjustment of its local oscillator. Once per frame, the remote handset enters a timing recovery state where the current state of the frame is compared with a previous state. When the cumulative timing slip is greater than a designated threshold, a frequency adjustment is made. During this exchange of commands between the remote handset and base unit, the remote handset continuously adjusts its local oscillator to achieve frequency alignment within, e.g., 1 part per million (ppm). Alternatively, frequency alignment may be achieved to a specified value. The period of the frequency alignment can be lengthened (or even suspended) during certain power critical modes to reduce power consumption. For example, the period of the link verify operations (and thus the frequency alignment) can be lengthened or suspended when the remote handset is being quick charged. Moreover, the period of the link verify operations can be adjusted based on a voltage level of the battery in the remote handset.

Claims

1. A link verification controller for a wireless device, comprising:

a default link verify period setting to establish a first period for a link verification operation between a remote device and a matching base unit during normal operations; and

a controller to adjust said established first period for said link verification based on a status of a battery of said remote device.

2. The link verification controller for a wireless device according to claim 1, further comprising:

a second link verify period setting to establish a second period for said link verification corresponding to a reduced power mode for said wireless device.

3. The link verification controller for a wireless device according to claim 1, wherein:

said second period is greater than said first period.

4. The link verification controller for a wireless device according to claim 1, wherein:

said second period is a suspension of said link verification operation.

5. The link verification controller for a wireless device according to claim 1, further comprising:

a link verification module to adjust an alignment of a timing signal in said remote device in accordance with a timing slip of a data frame received by at least one of said remote device and said base unit.

6. The link verification controller for a wireless device according to claim 5, wherein:

said timing slip is determined by a data frame received by said remote device.

7. The link verification controller for a wireless device according to claim 6, wherein:

said wireless device is a digital cordless telephone.

8. A method of determining a period for an operation between a remote unit and a matching base unit, said method comprising:

detecting a charging to a remote handset from a base unit; and

adjusting a period between a check of frequency alignment between said remote handset and said base unit based on a battery voltage level in said remote handset.

9. The method of determining a period for an operation between a remote unit and a matching base unit according to claim 8, further comprising:

suspending said check of said frequency alignment when said remote handset is in a predetermined mode.

10. The method of determining a period for an operation between a remote unit and a matching base unit according to claim 9, wherein:

said predetermined mode is a quick charge mode.

11. The method of determining a period for an operation between a remote unit and a matching base unit according to claim 8, wherein:

said period is adjusted between a predetermined maximum period and a predetermined minimum period.

12. Apparatus for determining a period for an operation between a remote unit and a matching base unit, comprising:

means for detecting a charging to a remote handset from a base unit; and

means for adjusting a period between a check of frequency alignment between said remote handset and said base unit based on a battery voltage level in said remote handset.

13. The apparatus for determining a period for an operation between a remote unit and a matching base unit according to claim 12, further comprising:

means for suspending said check of said frequency alignment when said remote handset is in a predetermined mode.

14. The apparatus for determining a period for an operation between a remote unit and a matching base unit according to claim 13, wherein:

said predetermined mode is a quick charge mode.

15. The apparatus for determining a period for an operation between a remote unit and a matching base unit according to claim 12, wherein:

said period is adjusted between a predetermined maximum period and a predetermined minimum period.