Ultra wide band (UWB) synchronisation search

• US 20050185697A1
• Filed: 12/29/2004
• Published: 08/25/2005
• Est. Priority Date: 02/03/2004
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushi Kaisha Toshiba
• Inventors: Gargin, Douglas John
• Granted Patent: US 7,505,516 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04B 2001/6908 using time hopping

Abstract

The present invention relates to ultra wide band (UWB) applications such as radar, position tracking and communications for example Ground Penetrating Radar (GPR) and Wireless Personal Area Networking (WPANs). The present invention provides an apparatus for synchronising a receiver to a received UWB signal having a known hopping code, the apparatus comprising: means for determining a parameter of the signal in a number of time slots; means for adding the parameter associated with each time slot to a number of corresponding of time and code offset accumulators; means for determining the code and time offset accumulator having an accumulated value according to a predetermined accumulator metric as the code and time offset required to synchronise the receiver.

Claims

1. Apparatus for synchronising a receiver to a received UWB signal having a known hopping code, the apparatus comprising:

a determinor arranged to determine a parameter of the signal in a number of time slots;

an adder arranged to add the parameter associated with each time slot to a number of corresponding time and code offset accumulators; and

a selector arranged to select a time and code offset accumulator having an accumulated value corresponding to a predetermined accumulator metric, to provide the code and time offset required to synchronise the receiver.

2. An apparatus according to claim 1 wherein the predetermined accumulator metric is the largest value.

3. An apparatus according to claim 1 wherein the determiner comprises a template signal generator for providing a template signal at a second time offset, and a correlator to correlate said template signal with said received signal in order to provide said parameter.

4. An apparatus according to claim 1, wherein the number of accumulations corresponding to each time slot is two or more for all time slots.

5. An apparatus according to claim 4 wherein the number of accumulations corresponding to each time slot is equal to the code length.

6. An apparatus according to claim 1 wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of time frames, the relative position of the pulse in each transmitter time frame according to the hopping code;

and wherein the apparatus comprises two or more parameter determiners corresponding to two or more time slots in a frame.

7. An apparatus according to claim 1 wherein the apparatus comprises one parameter determinor for each time slot.

8. An apparatus according to claim 1 wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of time frames, the relative position of the pulse in each transmitter time frame being determined according to the hopping code;

and wherein the apparatus comprises one or more parameter determinors corresponding to one or more time slots in a frame, and an adjustor to adjust the time slot in each frame for the or each said parameter determining means.

9. An apparatus according to claim 1 wherein the corresponding accumulators are determined according to:

10. An apparatus according to claim 1 wherein the accumulators are individually addressed memory locations.

11. An apparatus according to claim 1 and further comprising:

a verifier arranged to determine the frame offset and code offsets having N accumulated parameter values according to a predetermined verification metric;

a parameter determiner arranged to determine said parameter of a signal corresponding to said received signal but generated according to the time and code offset associated with each of said N accumulator values;

an offset selector arranged to select one of said N time and code offsets according to said corresponding parameter.

12. An apparatus according to claim 11 wherein the verification metric is selected from the group consisting of:

the highest accumulator values, and

the one highest accumulator value and the accumulator values associated with a range of time slots on either side of said highest value.

13. An apparatus according to claim 11 wherein said offset selector is arranged to select the highest parameter.

14. An apparatus according to claim 11 wherein the parameter is the correlation of the generated signal with the received signal.

15. An apparatus according to claim 1 further comprising a terminator arranged to attempt to determine a training sequence modulated onto the received signal following said synchronisation, and if unsuccessful further determining said parameter for further time in order to provide an improved estimate.

16. An apparatus according to claim 1 wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of time frames, the relative position of the pulse in each transmitter time frame according to the hopping code;

and wherein said determinor is arranged to determine said parameter for one time slot per frame.

17. An apparatus according to claim 1 wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of time frames, the relative position of the pulse in each transmitter time frame according to the hopping code;

and wherein said determinor is arranged to determine said parameter for two or more time slots per frame.

18. Use of an apparatus for synchronising a receiver to a received UWB signal having a known hopping code wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of transmitter time frames, the relative position of the pulse in each transmitter time frame is one of N_c time slots relative to the time frame start and is governed according to the hopping code;

and wherein the time hopping code ensures that all N_c time slots are stimulated one or more times.

19. Use of an apparatus according to claim 18 wherein the time hopping code further ensures that the numerical difference modulo N_c between consecutive hop code values is always unique for the entirety of the code except the numerical difference between the last and first code value.

20. Use of an apparatus according to claim 18 wherein the maximum distance, in terms of the number of frames, between any numerically identical code values within the code structure is equal to N_c frame durations.

21. Use of an apparatus according to claim 18 wherein the apparatus comprises:

a determiner arranged to determine a parameter of the signal in a number of time slots;

an adder arranged to add the parameter associated with each time slot to a number of corresponding time and code offset accumulators; and

a selector arranged to select a time and code offset accumulator having an accumulated value corresponding to a predetermined accumulator metric, to provide the code and time offset required to synchronise the receiver.

22. An apparatus for transmitting a UWB signal having a known hopping code, wherein the UWB signal comprises a series of pulses transmitted over a corresponding series of transmitter time frames, the relative position of the pulse in each transmitter time frame is one of N_c time slots relative to the time frame start and is governed according to the hopping code;

and wherein the time hopping code ensures that all N_c time slots are stimulated one or more times.

23. An apparatus according to claim 22 the time hopping code further ensures that the numerical difference modulo N_c between consecutive hop code values is always unique for the entirety of the code except the numerical difference between the last and first code value.

24. An apparatus according to claim 22 wherein the maximum distance, in terms of the number of frames, between any numerically identical code values within the code structure is equal to N_c frame durations.

25. A method for synchronising a receiver to a received UWB signal having a known hopping code, the method comprising:

determining a parameter of the signal in a number of time slots;

adding the parameter associated with each time slot to a number of corresponding of time and code offset accumulators;

determining the code and time offset accumulator having an accumulated value according to a predetermined accumulator metric as the code and time offset required to synchronise the receiver.

26. A method according to claim 25 wherein the predetermined accumulator metric is the largest value.

27. A method according to claim 25 wherein the parameter determining comprises generating a template signal at a second time offset, and correlating said template signal with said received signal in order to provide said parameter.

28. A method according to claim 25 wherein the number of accumulations corresponding to each time slot is two or more for all time slots.

29. A method according to claim 28 wherein the number of accumulations corresponding to each time slot is equal to the code length.

30. A method according to claim 25 wherein the corresponding accumulators are determined according to:

31. A method according to claim 25 and further comprising:

determining the frame offset and code offsets having N accumulated parameter values according to a predetermined verification metric;

determining said parameter of a signal corresponding to said received signal but generated according to the time and code offset associated with each of said N accumulator values;

selecting one of said N time and code offsets according to said corresponding parameter.

32. A method according to claim 31 wherein the verification metric is the highest accumulator values, or the one highest accumulator value and the accumulator values associated with a range of time slots on either side of said highest value.

33. A method according to claim 31 wherein said selection is arranged to select the highest parameter.

34. A method according to claim 31 wherein the parameter is the correlation of the generated signal with the received signal.

35. A method according to claim 25 further comprising attempting to determine a training sequence modulated onto the received signal following said synchronisation, and if unsuccessful further determining said parameter for further time in order to provide an improved estimate.

36. A carrier medium carrying processor control code for implementing a method/apparatus according to claim 25.

37. Apparatus for synchronising a receiver to a received UWB signal having a known hopping code, the apparatus comprising:

means for determining a parameter of the signal in a number of time slots;

means for adding the parameter associated with each time slot to a number of corresponding of time and code offset accumulators; and

means for determining the time and code offset accumulator having an accumulated value according to a predetermined accumulator metric as the code and time offset required to synchronise the receiver.