PREAMBLE STRUCTURE AND ACQUISITION FOR A WIRELESS COMMUNICATION SYSTEM

• US 20080279220A1
• Filed: 05/09/2007
• Published: 11/13/2008
• Est. Priority Date: 05/09/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wang, Michael Mao
• Granted Patent: US 8,929,353 B2
• Time in Patent Office: Days
• US Class Current: 370/500
• CPC Class Codes: H04J 3/02 Details electronic switching or gating H03K17/00
• CPC Class Codes: H04L 2027/0034 using hypothesis testing
• CPC Class Codes: H04L 2027/0095 in a preamble or similar structure
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657
• CPC Class Codes: H04L 27/2604 Multiresolution systems by means of multiresolution subcarriers H04L27/183, H04L27/3488
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

Techniques for sending sector/system information in TDM pilots using a hierarchical pilot structure are described. A base station sends multiple sets of bits for the sector/system information in multiple TDM pilots. The set of bits sent in a given TDM pilot may include bits sent in earlier TDM pilots. In one design, the base station generates a first TDM pilot based on a first set of bits, generates a second TDM pilot based on a second set of bits that includes the first set, generates a third TDM pilot based on all bits for the information, and sends the TDM pilots. A terminal performs detection to obtain a first detected value for the first TDM pilot, performs detection based on the first detected value to obtain a second detected value for the second TDM pilot, and performs detection based on the first and second detected values to obtain a third detected value for the third TDM pilot.

Claims

1. An apparatus comprising:

at least one processor configured to generate a plurality of pilots based on different sets of bits for information being sent in the plurality of pilots, each set including some or all bits of the information being sent, and to send the plurality of pilots in a plurality of time intervals; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the plurality of pilots are sent in sequential order and carry overlapping sets of bits for the information, with the set of bits for each pilot comprising bits for pilots sent earlier, if any, and at least one additional bit not yet sent.

3. The apparatus of claim 1, wherein the plurality of pilots carry non-overlapping sets of bits for the information.

4. The apparatus of claim 1, wherein the at least one processor is configured to generate a first pilot based on some of the bits for the information, to generate a second pilot based on all of the bits for the information, and to send the first and second pilots in first and second time intervals, respectively.

5. The apparatus of claim 1, wherein the at least one processor is configured to generate a first pilot based on a first set of bits for the information, to generate a second pilot based on a second set of bits for the information, the second set comprising the first set, to generate a third pilot based on all of the bits for the information, and to send the first, second, and third pilots in first, second, and third time intervals, respectively.

6. The apparatus of claim 5, wherein the information comprises 12 bits, the first set comprises 2 bits, and the second set comprises 8 bits and includes the 2 bits in the first set.

7. The apparatus of claim 1, wherein the at least one processor is configured to generate a pseudo-random number (PN) sequence for each pilot based on the set of bits being sent in the pilot, and to generate each pilot based on the PN sequence for the pilot.

8. The apparatus of claim 1, wherein for each of the plurality of pilots, the at least one processor is configured to generate a pseudo-random number (PN) sequence based on the set of bits being sent in the pilot, to generate pilot symbols based on the PN sequence, to map the pilot symbols to subcarriers used for the pilot, and to transform the mapped pilot symbols to obtain a sequence of samples for the pilot.

9. The apparatus of claim 1, wherein a pilot sent first in time among the plurality of pilots comprises multiple copies of a waveform.

10. The apparatus of claim 1, wherein each of the plurality of pilots is a time division multiplexed (TDM) pilot sent in a respective one of the plurality of time intervals.

11. The apparatus of claim 1, wherein the information being sent in the plurality of pilots comprises sector-specific information, or system information, or both.

12. A method comprising:

generating a plurality of pilots based on different sets of bits for information being sent in the plurality of pilots, each set including some or all bits of the information being sent; and

sending the plurality of pilots in a plurality of time intervals.

13. The method of claim 12, wherein the generating the plurality of pilots comprises

generating a first pilot based on some of the bits for the information, and

generating a second pilot based on all of the bits for the information.

14. The method of claim 12, wherein the generating the plurality of pilots comprises

generating a first pilot based on a first set of bits for the information,

generating a second pilot based on a second set of bits for the information, the second set comprising the first set, and

generating a third pilot based on all of the bits for the information.

15. The method of claim 12, wherein the generating the plurality of pilots comprises

generating a pseudo-random number (PN) sequence for each pilot based on the set of bits being sent in the pilot, and

generating each pilot based on the PN sequence for the pilot.

16. An apparatus comprising:

means for generating a plurality of pilots based on different sets of bits for information being sent in the plurality of pilots, each set including some or all bits of the information being sent; and

means for sending the plurality of pilots in a plurality of time intervals.

17. The apparatus of claim 16, wherein the means for generating the plurality of pilots comprises

means for generating a first pilot based on some of the bits for the information, and

means for generating a second pilot based on all of the bits for the information.

18. The apparatus of claim 16, wherein the means for generating the plurality of pilots comprises

means for generating a first pilot based on a first set of bits for the information,

means for generating a second pilot based on a second set of bits for the information, the second set comprising the first set, and

means for generating a third pilot based on all of the bits for the information.

19. The apparatus of claim 16, wherein the means for generating the plurality of pilots comprises

means for generating a pseudo-random number (PN) sequence for each pilot based on the set of bits being sent in the pilot, and

means for generating each pilot based on the PN sequence for the pilot.

20. A processor-readable medium including instructions stored thereon, comprising:

a first instruction set for generating a plurality of pilots based on different sets of bits for information being sent in the plurality of pilots, each set including some or all bits of the information being sent; and

a second instruction set for sending the plurality of pilots in a plurality of time intervals.

21. The processor-readable medium of claim 20, wherein the first instruction set comprises

a third instruction set for generating a first pilot based on some of the bits for the information, and

a fourth instruction set for generating a second pilot based on all of the bits for the information.

22. The processor-readable medium of claim 20, wherein the first instruction set comprises

a third instruction set for generating a first pilot based on a first set of bits for the information,

a fourth instruction set for generating a second pilot based on a second set of bits for the information, the second set comprising the first set, and

a fifth instruction set for generating a third pilot based on all of the bits for the information.

23. An apparatus comprising:

at least one processor configured to receive a plurality of pilots in a plurality of time intervals, the plurality of pilots carrying different sets of bits for information sent in the pilots, each set including some or all bits of the information, and to perform detection to recover a set of bits sent in each of the plurality of pilots; and

a memory coupled to the at least one processor.

24. The apparatus of claim 23, wherein the at least one processor is configured to perform detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot, and to perform detection for a second pilot based on the first detected value to obtain a second detected value for all bits of the information.

25. The apparatus of claim 23, wherein the at least one processor is configured to perform detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot, to perform detection for a second pilot based on the first detected value to obtain a second detected value for a second set of bits sent in the second pilot, the second set comprising the first set, and to perform detection for a third pilot based on the first and second detected values to obtain a third detected value for all bits of the information.

26. The apparatus of claim 23, wherein the at least one processor is configured to perform detection for each of the plurality of pilots based on detected values for pilots previously detected, if any, to obtain a detected value for the set of bits sent in the pilot being detected.

27. The apparatus of claim 23, wherein for each of the plurality of pilots, the at least one processor is configured to determine a detection metric for each of a plurality of hypothesized values for the pilot, and to provide a hypothesized value associated with a largest detection metric as a detected value for the set of bits sent in the pilot.

28. The apparatus of claim 27, wherein each hypothesized value for the pilot being detected comprises a first part for detected values for pilots previously detected, if any, and a second part for an unknown value for at least one additional bit sent in the pilot being detected.

29. The apparatus of claim 23, wherein for each of the plurality of pilots, the at least one processor is configured to derive a noise estimate based on captured samples for the pilot, to generate a plurality of pseudo-random number (PN) sequences for a plurality of hypothesized values for the pilot, to descramble the captured samples based on the plurality of PN sequences to obtain a plurality of sequences of descrambled samples for the plurality of hypothesized values, to derive a plurality of detection metrics for the plurality of hypothesized values based on the plurality of sequences of descrambled samples and the noise estimate, and to provide a hypothesized value associated with a largest detection metric as a detected value for the set of bits sent in the pilot.

30. The apparatus of claim 29, wherein for each of the plurality of pilots, the at least one processor is configured to transform the captured samples to frequency domain to obtain received symbols, to remove modulation in the received symbols based on the PN sequence for each hypothesized value to obtain descrambled symbols for the hypothesized value, and to transform the descrambled symbols for each hypothesized value to obtain a sequence of descrambled samples for the hypothesized value.

31. The apparatus of claim 29, wherein to derive a detection metric for a hypothesized value, the at least one processor is configured to compute energy of each descrambled sample in a sequence of descrambled samples for the hypothesized value, and to compute the detection metric based on energies for the sequence of descrambled samples and the noise estimate.

32. A method comprising:

receiving a plurality of pilots in a plurality of time intervals, the plurality of pilots carrying different sets of bits for information sent in the pilots, each set including some or all bits of the information; and

performing detection to recover a set of bits sent in each of the plurality of pilots.

33. The method of claim 32, wherein the performing detection comprises

performing detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot, and

performing detection for a second pilot based on the first detected value to obtain a second detected value for all bits of the information.

34. The method of claim 32, wherein the performing detection comprises

performing detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot,

performing detection for a second pilot based on the first detected value to obtain a second detected value for a second set of bits sent in the second pilot, the second set comprising the first set, and

performing detection for a third pilot based on the first and second detected values to obtain a third detected value for all bits of the information.

35. The method of claim 32, wherein the performing detection comprises, for each of the plurality of pilots,

determining a detection metric for each of a plurality of hypothesized values for the pilot, and

providing a hypothesized value associated with a largest detection metric as a detected value for the set of bits sent in the pilot.

36. An apparatus comprising:

means for receiving a plurality of pilots in a plurality of time intervals, the plurality of pilots carrying different sets of bits for information sent in the pilots, each set including some or all bits of the information; and

means for performing detection to recover a set of bits sent in each of the plurality of pilots.

37. The apparatus of claim 36, wherein the means for performing detection comprises

means for performing detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot, and

means for performing detection for a second pilot based on the first detected value to obtain a second detected value for all bits of the information.

38. The apparatus of claim 36, wherein the means for performing detection comprises

means for performing detection for a first pilot to obtain a first detected value for a first set of bits sent in the first pilot,

means for performing detection for a second pilot based on the first detected value to obtain a second detected value for a second set of bits sent in the second pilot, the second set comprising the first set, and

means for performing detection for a third pilot based on the first and second detected values to obtain a third detected value for all bits of the information.

39. The apparatus of claim 36, wherein the means for performing detection comprises, for each of the plurality of pilots,

means for determining a detection metric for each of a plurality of hypothesized values for the pilot, and

means for providing a hypothesized value associated with a largest detection metric as a detected value for the set of bits sent in the pilot.

40. A processor-readable medium including instructions stored thereon, comprising:

first instructions for receiving a plurality of pilots in a plurality of time intervals, the plurality of pilots carrying different sets of bits for information sent in the pilots, each set including some or all bits of the information; and

second instructions set for performing detection to recover a set of bits sent in each of the plurality of pilots.