Digital wireless communications system and a wireless radio station with timing error compensation based on an accumulated timing error between reception of messages

• US 6,154,642 A
• Filed: 10/16/1997
• Issued: 11/28/2000
• Est. Priority Date: 10/24/1996
• Status: Expired due to Fees

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Dumont, Frederik A. J., Schuur, Cornelis C. M., Vos, Hermanus J. M.
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): CHOW, CHARLES CHIANG
• Application Number:
  US08/951,702
• Time in Patent Office: 1,139 Days
• Field of Search: 455/574, 455/455, 455/38.3, 455/403, 455/343, 455/573, 455/502, 370/100.1, 370/505, 370/350, 370/311, 370/516, 370/517, 375/12, 375/356, 375/357, 375/371, 179/15
• US Class Current: 455/403
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically
• CPC Class Codes: H04W 56/003 Arrangements to increase tolerance to errors in transmission or reception timing
• CPC Class Codes: H04W 56/0035 detecting errors in frequency or phase
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In a time division multiple access wireless communication system, a wireless radio station performs a timing error compensation method. The wireless radio station receives messages including a synchronisation pattern. The wireless radio station adopts a power down mode between reception of messages, and accumulates a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, during a predetermined time interval between reception of successive messages and before an expected reception of a next message. Thereafter, the wireless radio station at least substantially undoes the accumulated timing error, before the expected reception of the next message such that the timing error is compensated before the expected reception of the next message.

Claims

1. A digital wireless communications system comprising a first wireless radio station coupled to a network and a second wireless radio station arranged for wireless communication with the first wireless station via at least one time slot of a communications frame, in which system the first station comprises a master clock and is arranged to transmit messages to the second station comprising a synchronisation pattern, and in which system the second station comprises power management circuitry, local timing circuitry, and is at least controllable so as to operate in an active reception mode and in a power down mode, whereby the power down mode is adopted between reception of messages outside the active mode, the second station comprises register means for accumulating a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, said timing error being accumulated during a predetermined time interval between reception of messages and before an expected reception of a next message, and the second station comprises means for at least substantially undoing the accumulated timing error before the expected reception of the next message by controlling the local timing circuitry in accordance with the accumulated timing error such that the timing error is compensated for just before the expected reception of the next message, said controlling of the local timing circuitry being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is close to one.

2. A digital wireless communications system according to claim 1, wherein a timing error is measured over at least one frame when the second station is in active mode, and as an initial estimation of the accumulated timing error the timing error measured during said one period is multiplied by the number of frames between the messages as received when the second station adopts the power down mode.

3. A digital wireless communications system according to claim 2, wherein a power down mode is stepwise and substantially prolonged after at least one compensation step at a time.

4. A digital wireless communications system according to claim 1, wherein a residual timing error is determined after a compensation step and after reception of a message, and is stored in the register means before further accumulation of the timing error to be compensated for before the next message.

5. A digital wireless communication system according to claim 1, wherein the means for undoing the accumulated timing error are configured to undo the accumulated timing error in a number of undoing steps.

6. A wireless radio station for use in a communications system arranged for wireless communication with another wireless radio station via at least one time slot of a communications frame, in which system the other radio station comprises a master clock and is arranged to transmit messages to the wireless station comprising a synchronisation pattern, and in which system the wireless radio station comprises power management circuitry, local timing circuitry, and is at least controllable so as to operate in an active reception mode and in a power down mode, whereby the power down mode is adopted between reception of messages outside the active mode, the wireless radio station comprises register means for accumulating a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, said timing error being accumulated during a predetermined time interval between reception of messages and before an expected reception of a next message, and the wireless radio station comprises means for at least substantially undoing the accumulated timing error before the expected reception of the next message by controlling the local timing circuitry in accordance with the accumulated timing error such that the timing error is compensated for just before the expected reception of the next message, said controlling of the local timing circuitry being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is close to one.

11. A wireless radio station as claimed in claim 6, wherein a residual timing error is determined after a compensation step and after reception of a message, and is stored in the register means before further accumulation of the timing error to be compensated for before the next message.

16. A wireless radio station as claimed in claim 6, wherein the means for undoing the accumulated timing error are configured to undo the accumulated timing error in a number of undoing steps.

7. In a digital wireless communication system comprising a first wireless radio station coupled to a network and a second wireless radio station arranged for wireless communication with the first wireless station through at least one time slot of a communication frame, said second wireless radio station being controllable so as to operate in an active reception mode and a power down mode, a method for undoing a timing error, said method being used in said second wireless radio station and said method comprising:

receiving messages comprising a synchronisation pattern;

adopting said power down mode between reception of messages;

accumulating a timing error representing an accumulated difference between expected times of arrival of said synchronisation patterns and actual times of arrival of said synchronisation patterns, during a predetermined time interval between reception of successive messages and before an expected reception of a next message; and

at least substantially undoing said timing error before said expected reception of said next message such that said timing error is compensated before said expected reception of said next message, said undoing being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is close to one.

13. A method as claimed in claim 7, determining a residual timing error after a compensation step and after reception of a message, and storing said residual timing error before further accumulation of the timing error to be compensated for before the next message.

18. A method as claimed in claim 7, undoing the accumulated timing error in a number of undoing steps.

8. A digital wireless communications system comprising a first wireless radio station coupled to a network and a second wireless radio station arranged for wireless communication with the first wireless station via at least one time slot of a communications frame, in which system the first station comprises a master clock and is arranged to transmit messages to the second station comprising a synchronisation pattern, and in which system the second station comprises power management circuitry, local timing circuitry, and is at least controllable so as to operate in an active reception mode and in a power down mode, whereby the power down mode is adopted between reception of messages outside the active mode, the second station comprises register means for accumulating a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, said timing error being accumulated during a predetermined time interval between reception of messages and before an expected reception of a next message, and the second station comprises means for at least substantially undoing the accumulated timing error before the expected reception of the next message by controlling the local timing circuitry in accordance with the accumulated timing error such that the timing error is compensated for just before the expected reception of the next message, said controlling of the local timing circuitry being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is substantially smaller than one.

14. A digital wireless communication system as claimed in claim 8, wherein a residual timing error is determined after a compensation step and after reception of a message, and is stored in the register means before further accumulation of the timing error to be compensated for before the next message.

19. A digital wireless communication system as claimed in claim 8, wherein the means for undoing the accumulated timing error are configured to undo the accumulated timing error in a number of undoing steps.

9. A wireless radio station for use in a communications system arranged for wireless communication with another wireless radio station via at least one time slot of a communications frame, in which system the other radio station comprises a master clock and is arranged to transmit messages to the wireless station comprising a synchronisation pattern, and in which system the wireless radio station comprises power management circuitry, local timing circuitry, and is at least controllable so as to operate in an active reception mode and in a power down mode, whereby the power down mode is adopted between reception of messages outside the active mode, the wireless radio station comprises register means for accumulating a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, said timing error being accumulated during a predetermined time interval between reception of messages and before an expected reception of a next message, and the wireless radio station comprises means for at least substantially undoing the accumulated timing error before the expected reception of the next message by controlling the local timing circuitry in accordance with the accumulated timing error such that the timing error is compensated for just before the expected reception of the next message, said controlling of the local timing circuitry being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is substantially smaller than one.

12. A wireless radio station as claimed in claim 9, wherein a residual timing error is determined after a compensation step and after reception of a message, and is stored in the register means before further accumulation of the timing error to be compensated for before the next message.

17. A wireless radio station as claimed in claim 9, wherein the means for undoing the accumulated timing error are configured to undo the accumulated timing error in a number of undoing steps.

10. In a digital wireless communication system comprising a first wireless radio station coupled to a network and a second wireless radio station arranged for wireless communication with the first wireless station through at least one time slot of a communication frame, said second wireless radio station being controllable so as to operate in an active reception mode and a power down mode, a method for undoing a timing error, said method being used in said second wireless radio station and said method comprising:

receiving messages comprising a synchronisation pattern;

adopting said power down mode between reception of messages;

accumulating a timing error representing an accumulated difference between expected times of arrival of said synchronisation patterns and actual times of arrival of said synchronisation patterns, during a predetermined time interval between reception of successive messages and before an expected reception of a next message; and

at least substantially undoing said timing error before said expected reception of said next message such that said timing error is compensated before said expected reception of said next message, said undoing being performed within a first time period that is short with respect to a second time period between two successive messages, and said first time period ending at an instant before the expected reception of the next message, said instant being such that a ratio of a difference between said instant and a reception instant of a message preceding the next message, and of a difference between a reception instant of the next message and the reception instant of the message preceding the next message is substantially smaller than one.

15. A method as claimed in claim 10, determining a residual timing error is determined after a compensation step and after reception of a message, and storing said residual timing error before further accumulation of the timing error to be compensated for before the next message.

20. A method as claimed in claim 10, undoing the accumulated timing error in a number of undoing steps.