Hopping pilot pattern for telecommunications

• US 20070133462A1
• Filed: 12/02/2005
• Published: 06/14/2007
• Est. Priority Date: 12/02/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Guey, Jiann-Ching
• Granted Patent: US 7,711,029 B2
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04J 13/0074 Code shifting or hopping
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0058 Allocation criteria

Abstract

A transmitter (22) of a telecommunications system transmits hopped pilot signals as a distinct (i.e., locally unique) time-frequency shift of a time frequency plane array wherein the pilot signals are hopped using a hopping sequence. Differing transmitters of the system (20) preferably transmit using different time-frequency shifts of the same time frequency plane array. The transmitter (22) knows which hopping sequence to employ to generate the time frequency plane array in view of its storage of the hopping sequence, and further knows how to perform its signature time-frequency shift the time frequency plane array thusly created in view of its storage of the time-frequency shift pattern. A receiver (24) identifies a transmitter from which the receiver obtains signals by detecting the particular time-frequency shift of the time frequency plane array and associating the particular time-frequency shift with the originating transmitter. Upon detecting the time frequency plane array of its received signals, the receiver (24), which knows the hopping sequence employed to generate the time frequency plane array, can determine how the time frequency plane array has been time-frequency shifted, and upon determining the pattern of the shift can associate the received signals with one of the transmitters for which the receiver (24) has stored time-frequency shift patterns in its library (86).

Claims

1. A transmitter which transmits hopped pilot signals as a locally unique time-frequency shift of a time frequency plane array wherein the pilot signals are hopped using a hopping sequence.

2. The apparatus of claim 1, wherein the transmitter is an orthogonal frequency division multiplexing (OFDM) transmitter which further comprises:

a modulator for using a data stream to generate plural modulated carriers;

an Inverse Fast Fourier Transform (IFFT) unit for transforming modulated carriers into a sequence of time domain samples;

means for applying the sequence of time domain samples to a channel;

means for combining user data and the pilot signals for generating the data stream applied to the modulator.

3. The apparatus of claim 2, wherein the combining means is a multiplexer.

4. The apparatus of claim 1, wherein the hopping sequence upon which the time frequency plane array is based is configured so that any two time-frequency shifts of the time frequency plane array has a predetermined number of coincidences.

5. The apparatus of claim 4, wherein the predetermined number of coincidences is a non-negative integer.

6. The apparatus of claim 1, wherein the hopping sequence upon which the time frequency plane array is based is a Costas sequence.

7. The apparatus of claim 6, wherein the hopping sequence upon which the time frequency plane array is based is a periodic hopping sequence wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

8. The apparatus of claim 1, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

9. The apparatus of claim 8, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

10. The apparatus of claim 1, wherein the pilot signals are for providing channel estimation and synchronization, and wherein the locally unique time-frequency shift of the time frequency plane array is configured for providing device identification.

11. The apparatus of claim 10, wherein a device identified the device identification is a radio access network node.

12. The apparatus of claim 10, wherein a device identified the device identification is a wireless mobile station.

13. The apparatus of claim 1, wherein the pilot signals are hopped with respect to one of time and frequency but not both.

14. A telecommunications system comprising plural communicating devices, and wherein each of the plural communicating devices are identified by a permutation of a time-frequency pattern of signals transmitted therefrom, the permutation resulting either in the time-frequency pattern or a cyclic shifting of the time-frequency pattern.

15. The apparatus of claim 14, wherein the time-frequency pattern includes hopped pilot signals.

16. The apparatus of claim 15, wherein the hopped pilot signals are hopped either in a frequency domain or a time domain.

17. The apparatus of claim 15, wherein the hopped pilot signals are hopped in accordance with a Costas sequence.

18. The apparatus of claim 15, wherein the hopped pilot signals are hopped in accordance with a Costas sequence, and wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

19. The apparatus of claim 15, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

20. The apparatus of claim 19, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

21. The apparatus of claim 14, wherein a device identified by the permutation of a time-frequency pattern is a radio access network node.

22. The apparatus of claim 14, wherein the device identified by the permutation of a time-frequency pattern is a wireless mobile station.

23. A telecommunications system comprising:

a first orthogonal frequency division multiplexing (OFDM) transmitter which transmits hopped pilot signals as a first locally unique time-frequency shift of a time frequency plane array wherein the pilot signals are hopped using a hopping sequence;

a second orthogonal frequency division multiplexing (OFDM) transmitter which transmits hopped pilot signals as a second locally unique time-frequency shift of the same time frequency plane array;

wherein the first locally unique time-frequency shift is different from the second locally unique time-frequency shift;

a receiver which identifies a transmitter from which it receives orthogonal frequency division multiplexing (OFDM) signals in accordance with whether received signals are those of the first locally unique time-frequency shift or the second locally unique time-frequency shift of the time frequency plane array.

24. The apparatus of claim 23, wherein the hopping sequence upon which the time frequency plane array is based is a Costas sequence.

25. The apparatus of claim 24, wherein the hopping sequence upon which the time frequency plane array is based is a periodic hopping sequence wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

26. The apparatus of claim 23, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

27. The apparatus of claim 26, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

28. The apparatus of claim 23, wherein the pilot signals are for providing channel estimation and synchronization, and wherein the locally unique time-frequency shift of the time frequency plane array is configured for providing device identification.

29. The apparatus of claim 28, wherein a device identified the device identification is a radio access network node.

30. The apparatus of claim 28, wherein a device identified the device identification is a wireless mobile station.

31. A telecommunications node comprising:

a first antenna which transmits hopped pilot signals as a first locally unique time-frequency shift of a time frequency plane array wherein the pilot signals are hopped using a hopping sequence;

a second antenna which transmits hopped pilot signals as a second locally unique time-frequency shift of the same time frequency plane array;

wherein the first locally unique time-frequency shift is different from the second locally unique time-frequency shift.

32. The apparatus of claim 31, wherein the hopping sequence upon which the time frequency plane array is based is a Costas sequence.

33. The apparatus of claim 32, wherein the hopping sequence upon which the time frequency plane array is based is a periodic hopping sequence wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

34. The apparatus of claim 31, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

35. The apparatus of claim 34, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

36. The apparatus of claim 31, wherein the pilot signals are for providing channel estimation and synchronization, and wherein the locally unique time-frequency shift of the time frequency plane array is configured for providing device identification.

37. The apparatus of claim 36, wherein the node is a radio access network node.

38. The apparatus of claim 36, wherein the node is a wireless mobile station.

39. A method of operating a telecommunications system comprising:

transmitting, from a first transmitter, hopped pilot signals as a first locally unique time-frequency shift of a time frequency plane array wherein the pilot signals are hopped using a hopping sequence;

transmitting, from a second transmitter, hopped pilot signals as a second locally unique time-frequency shift of the same time frequency plane array, wherein the first locally unique time-frequency shift is different from the second locally unique time-frequency shift; and

,

identifying a transmitter from which a receiver receives signals in accordance with whether received signals are those of the first locally unique time-frequency shift or the second locally unique time-frequency shift of the time frequency plane array.

40. The method of claim 39, wherein the hopping sequence upon which the time frequency plane array is based is a Costas sequence.

41. The method of claim 40, wherein the hopping sequence upon which the time frequency plane array is based is a periodic hopping sequence wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

42. The method of claim 39, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

43. The method of claim 42, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

44. The method of claim 39, wherein the pilot signals are for providing channel estimation and synchronization, and wherein the locally unique time-frequency shift of the time frequency plane array is configured for providing device identification.

45. The method of claim 44, wherein a device identified the device identification is a radio access network node.

46. The method of claim 44, wherein a device identified the device identification is a wireless mobile station.

47. The method of claim 39, wherein the first transmitter is a first orthogonal frequency division multiplexing (OFDM) transmitter and the second transmitter is a second orthogonal frequency division multiplexing (OFDM) transmitter, and wherein the method further comprises:

transmitting, from the first orthogonal frequency division multiplexing (OFDM) transmitter, data and the hopped pilot signals as the first locally unique time-frequency shift of the time frequency plane array;

transmitting, from the second orthogonal frequency division multiplexing (OFDM) transmitter, data and the hopped pilot signals as the second locally unique time-frequency shift of the time frequency plane array.

48. A receiver which identifies a transmitter from which it receives signals in accordance with a time-frequency shift of a time frequency plane array which includes the received signals, a pattern of pilot signals in the time frequency plane array reflecting hopping of the pilot signals in accordance with a hopping sequence.

49. The apparatus of claim 48, wherein the receiver receives orthogonal frequency division multiplexing (OFDM) signals in accordance with the time-frequency shift of the time frequency plane array which includes the received signals, the time frequency plane array being an expression of a combination of pilot signals and user data.

50. The apparatus of claim 48, wherein the hopping sequence upon which the time frequency plane array is based is a Costas sequence.

51. The apparatus of claim 50, wherein the hopping sequence upon which the time frequency plane array is based is a periodic hopping sequence wherein the Costas sequence repeats for one or more periods to accommodate a number of pilot signals in one of the time domain and the frequency domain.

52. The apparatus of claim 48, wherein the hopping sequence upon which the time frequency plane array is based is a perfect periodic Costas sequence.

53. The apparatus of claim 52, wherein the perfect periodic Costas sequence is configured by augmenting a Welsh-constructed periodic Costas array with an empty row or an empty column.

54. The apparatus of claim 48, wherein the pilot signals are for providing channel estimation and synchronization, and wherein the locally unique time-frequency shift of the time frequency plane array is configured for providing device identification.

55. The apparatus of claim 54, wherein a device identified the device identification is a radio access network node.

56. The apparatus of claim 54, wherein a device identified the device identification is a wireless mobile station.