Method for timing detection

• US 20060269018A1
• Filed: 05/04/2006
• Published: 11/30/2006
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Li, Guogang, Li, Qian, Jiang, Xuefeng
• Granted Patent: US 7,720,179 B2
• Time in Patent Office: Days
• US Class Current: 375/343
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H04J 3/0608 Detectors therefor, e.g. correlators, state machines
• CPC Class Codes: H04L 2027/0024 at the receiver end
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A wireless communication system comprises a sampling module that samples a first portion and a second portion of a channel using a sampling time. A correlator module selectively correlates the first portion and the second portion, generates correlation samples, and calculates an offset based on the correlation samples. A timing module selectively adjusts the sampling time based on the offset.

Claims

1. A wireless communication system, comprising:

a sampling module that samples a first portion and a second portion of a channel using a sampling time;

a correlator module that selectively correlates said first portion and said second portion, that generates correlation samples, and that calculates an offset based on said correlation samples;

a timing module that selectively adjusts said sampling time based on said offset.

2. The wireless communication system of claim 1 wherein said first portion is a preamble (PR) and said second portion is a unique word (UW).

3. The wireless communication system of claim 1 wherein said correlator module selectively correlates said first portion and said second portion when said channel is a traffic channel.

4. The wireless communication system of claim 1 wherein said timing module adjusts said sampling time based on said offset when said channel is a traffic channel.

5. The wireless communication system of claim 1 wherein said timing module adjusts said sampling time based on said first portion when said channel is a control channel.

6. The wireless communication system of claim 1 wherein said correlation module generates a correlation waveform using said correlation samples, determines a peak of said correlation waveform, and calculates said offset based on a distance of said peak from one of said correlation samples.

7. The wireless communication system of claim 1 wherein said correlation module generates a correlation waveform using said correlation samples and determines a peak of said correlation waveform using parabolic curve fitting, and calculates said offset based on a distance of said peak from one of said correlation samples.

8. The wireless communication system of claim 1 wherein said correlator module correlates said first portion and said second portion for each time slot of said channel.

9. The wireless communication system of claim 1 wherein said correlator module correlates using training symbols in said channel.

10. The wireless communication system of claim 1 wherein said channel comprises a plurality of time slots and wherein said timing module calculates said offset for each of said time slots.

11. The wireless communication system of claim 1 wherein said correlator module estimates a location of said second portion in a traffic channel based on said sampling time of a control channel and based on a burst detected in said control channel.

12. The wireless communication system of claim 1 further comprising a burst detector module that communicates with said sampling module, that detects a burst in a control channel, and that generates a burst-detect signal when a moving average of one of N phases is less than a predetermined threshold, wherein said one of N phases is an array of Nth sample of every symbol in a signal sampled at a sampling rate of N samples per symbol, and N is an integer greater than 1.

13. The wireless communication system of claim 12 wherein said burst-detect signal activates said timing module.

14. The wireless communication system of claim 12 further comprising a carrier offset estimator module that communicates with said burst detector module and that generates a carrier offset for a control channel when activated by said burst-detect signal.

15. The wireless communication system of claim 14 further comprising a carrier recovery module that communicates with said sampling module and that uses a phase-locked loop (PLL) to recover a carrier signal from a sample output by said sampling module.

16. The wireless communication system of claim 15 wherein said PLL is initialized with said carrier offset and wherein said carrier offset is update when said PLL locks for each time slot in said channel.

17. The wireless communication system of claim 15 further comprising a differential decoder module that communicates with said carrier recovery module and that decodes a symbol from said sample.

18. The wireless communication system of claim 1 wherein said sampling module uses one of a cubic interpolator and a parabolic interpolator.

19. The wireless communication system of claim 1 wherein an output sample rate of said sampling module is equal to a symbol rate and wherein an input sample rate of said sampling module is an integer multiple of said symbol rate.

20. A personal handy-phone system (PHS) receiver comprising the wireless communication system of claim 1.

21. A method for operating wireless communication system, comprising:

sampling a first portion and a second portion of a channel using a sampling time;

selectively correlating said first portion and said second portion;

generating correlation samples;

calculating an offset based on said correlation samples; and

selectively adjusting said sampling time based on said offset.

22. The method of claim 21 wherein said first portion is a preamble (PR) and said second portion is a unique word (UW).

23. The method of claim 21 further comprising selectively correlating said first portion and said second portion when said channel is a traffic channel.

24. The method of claim 21 further comprising adjusting said sampling time based on said offset when said channel is a traffic channel.

25. The method of claim 21 further comprising adjusting said sampling time based on said first portion when said channel is a control channel.

26. The method of claim 21 further comprising:

generating a correlation waveform using said correlation samples;

determining a peak of said correlation waveform; and

calculating said offset based on a distance of said peak from one of said correlation samples.

27. The method of claim 21 further comprising:

generating a correlation waveform using said correlation samples;

determining a peak of said correlation waveform using parabolic curve fitting, and

calculating said offset based on a distance of said peak from one of said correlation samples.

28. The method of claim 21 further comprising correlating said first portion and said second portion for each time slot of said channel.

29. The method of claim 21 further comprising correlating using training symbols in said channel.

30. The method of claim 21 wherein said channel comprises a plurality of time slots and further comprising calculating said offset for each of said time slots.

31. The method of claim 21 further comprising estimating a location of said second portion in a traffic channel based on said sampling time of a control channel and based on a burst detected in said control channel.

32. The method of claim 21 further comprising:

detecting a burst in a control channel; and

generating a burst-detect signal when a moving average of one of N phases is less than a predetermined threshold,

wherein said one of N phases is an array of Nth sample of every symbol in a signal sampled at a sampling rate of N samples per symbol, and N is an integer greater than 1.

33. The method of claim 32 further comprising adjusting said sampling time when said burst-detect signal occurs.

34. The method of claim 32 further comprising generating a carrier offset for a control channel when said burst-detect signal occurs.

35. The method of claim 34 further comprising using a phase-locked loop to recover a carrier signal from a sample output.

36. The method of claim 35 further comprising:

initializing said PLL with said carrier offset; and

updating said carrier offset when said PLL locks for each time slot in said channel.

37. The method of claim 35 further comprising decoding a symbol from said sample.

38. The method of claim 21 further comprising using one of a cubic interpolator and a parabolic interpolator.

39. The method of claim 21 further comprising:

setting an output sample rate equal to a symbol rate; and

setting an input sample rate equal to an integer multiple of said symbol rate.