Overhead signaling in a wireless communication system

• US 8,005,158 B2
• Filed: 07/14/2006
• Issued: 08/23/2011
• Est. Priority Date: 04/14/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jin, Hui, Laroia, Rajiv, Li, Junyi, Srinivasan, Murari, Leonidov, Alexander
• Primary Examiner(s): Payne; David C.
• Assistant Examiner(s): Perez; James M
• Application Number:
  US11/487,260
• Publication Number:
  US 20070242639A1
• Time in Patent Office: 1,866 Days
• Field of Search: 375/130, 375132-137, 375259-261
• US Class Current: 375/261
• CPC Class Codes: N/A

Abstract

Improved ways of communicating assignment signals using flash signaling are described, e.g., for wireless terminals with low SNR, that are more robust against large variation of channel gains due to e.g., frequency selective fading and fast fading in time. Coding and modulation methods and apparatus that have excellent properties against symbol erasures are described. The use of flash signaling provides an improved assignment channel having strong performance on the fading channel without compromising the performance on the AWGN channel. In one exemplary embodiment, the coding and modulation method can tolerate up to 5 erased symbols out of 8 transmitted symbols. One embodiment reduces or minimizes the sector interference on the flash assignment by improving or maximizing orthogonality between different sectors. In addition, one embodiment describes improved ways of swapping flash assignment tone-symbols in the presence other high priority signals, like sector pilots and sector null pilots.

Claims

1. A method of communicating information bits in a wireless communication system, the method comprising:

dividing the information bits into at least one modulation symbol bit and at least one position bit;

identifying modulation symbols based on the at least one modulation symbol bit;

determining a subset of tone symbols based on the at least one position bit;

determining whether any of the subset of tone symbols is reserved for use by any one of a plurality of higher priority channels;

when it is determined that one of the subset of tone symbols is reserved for use by any one of the plurality of higher priority channels, modifying the subset of tone symbols by performing one operation from the group of operations consisting of;

i) a tone symbol replacement operation and ii) a tone symbol dropping operation; and

modulating the modulation symbols to the subset of tone symbols.

2. The method of claim 1, wherein the modulation symbols comprises quadrature phase shift keying modulation symbols and wherein a ratio of a position bit number of position bits to a modulation symbol bit number of modulation symbol bits is two to five.

3. The method of claim 1, wherein said step of modifying the subset of tone symbols includes:

i) replacing the one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels with a substitute tone symbol when a substitute tone symbol is available; and

ii) dropping said one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels from said subset when a substitute tone symbol is not available.

4. The method of claim 3, wherein the higher priority channels include a pilot channel and a sector null channel.

5. The method of claim 3, further comprising:

performing a search of a predetermined set of substitute tone symbols for an available substitute tone symbol.

6. The method of claim 5, further comprising:

identifying at least one of the substitute tone symbols as a reserved tone symbol reserved for use by a second sector; and

wherein the performing a search of a predetermined set of substitute tone symbols comprises searching other substitute tone symbols before searching the identified at least one substitute tone symbol.

7. The method of claim 1, wherein the modulation symbols are high power modulation symbols, each high power modulation symbol being a modulation symbol that is to be transmitted at least 3 dB above an average per symbol transmission power used to transmit modulation symbols used to communicate traffic channel information;

and

wherein said method includes dropping at least one of the subset of tone symbols prior to performing said modulating.

8. A method of communicating information bits in a wireless communication system, the method comprising:

dividing the information bits into at least one modulation symbol bit and at least one position bit;

identifying modulation symbols based on the at least one modulation symbol bit by;

i) performing a vector matrix multiplication operation on a bit vector u comprising the modulation symbol bits, the matrix multiplication operation including multiplying the bit vector by a matrix G to produce a vector of coded bits, wherein;

9. The method of claim 8, further comprising:

transmitting each of the quadrature phase shift keying modulation symbols in one tone symbol of the determined subset of tone symbols.

10. A non-transitory computer readable medium embodying computer executable instructions for controlling a communications device in a wireless OFDM communication system, to perform the steps of:

dividing information bits into at least one modulation symbol bit and at least one position bit;

identifying modulation symbols based on the at least one modulation symbol bits;

determining a subset of tone symbols based on the at least one position bits;

determining whether any of the subset of tone symbols is reserved for use by any one of a plurality of higher priority channels;

when it is determined that one of the subset of tone symbols is reserved for use by any one of the plurality of higher priority channels, modifying the subset of tone symbols by performing one operation from the group of operations consisting of;

i) a tone symbol replacement operation and ii) a tone symbol dropping operation; and

modulating the modulation symbols to the subset of tone symbols.

11. The non-transitory computer readable medium of claim 10, wherein the modulation symbols comprise quadrature phase shift keying modulation symbols and wherein a ratio of a position bit number of position bits to a modulation symbol bit number of modulation symbol bits is two to five.

12. The non-transitory computer readable medium of claim 10, wherein said step of modifying the subset of tone symbols includes:

i) replacing the one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels with a substitute tone symbol when a substitute tone symbol is available; and

ii) dropping said one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels from said subset when a substitute tone symbol is not available.

13. The non-transitory computer readable medium of claim 12, wherein the higher priority channels include a pilot channel and a sector null channel.

14. The non-transitory computer readable medium of claim 12, wherein the computer executable instructions further control the communications device to perform the step of:

performing a search of a predetermined set of substitute tone symbols for an available substitute tone symbol.

15. The non-transitory computer readable medium of claim 14, wherein the computer executable instructions further control the communications device to perform the step of:

identifying at least one of the substitute tone symbols as a reserved for use by a second sector; and

wherein the performing a search of a predetermined set of substitute tone symbols comprises searching other substitute tone symbols before searching the identified at least one substitute tone symbol.

16. The non-transitory computer readable medium of claim 10, wherein the modulation symbols are high power modulation symbols, each high power modulation symbol being a modulation symbol that is to be transmitted at least 3 dB above an average per symbol transmission power used to transmit modulation symbols used to communicate traffic channel information.

17. A non-transitory computer readable medium embodying computer executable instructions for controlling a communications device in a wireless OFDM communication system to perform the steps of:

dividing information bits into at least one modulation symbol bit and at least one position bit;

identifying modulation symbols based on the at least one modulation symbol bits by;

i) performing a vector matrix multiplication operation on a bit vector u comprising the modulation symbol bits, the matrix multiplication operation including multiplying the bit vector by a matrix G to produce a vector of coded bits, wherein;

18. The non-transitory computer readable medium of claim 17, wherein the computer executable instructions further control the communications device to perform the step of:

transmitting each of the quadrature phase shift keying modulation symbols in one tone symbol of the determined subset of tone symbols.

19. A wireless communication device for communicating information bits in a wireless OFDM communication system, the wireless communication device comprising:

means for dividing the information bits into at least one modulation symbol bit and at least one position bit;

means for identifying modulation symbols based on the at least one modulation symbol bits;

means for determining a subset of tone symbols based on the at least one position bits;

means for determining whether any of the subset of tone symbols is reserved for use by any one of a plurality of higher priority channels;

means for modifying the subset of tone symbols by performing one operation from the group of operations consisting of;

i) a tone symbol replacement operation and ii) a tone symbol dropping operation, when it is determined that one of the subset of tone symbols is reserved for use by any one of the plurality of higher priority channels; and

means for modulating the modulation symbols to the subset of tone symbols.

20. The wireless communication device of claim 19, wherein the modulation symbols comprise quadrature phase shift keying modulation symbols and wherein a ratio of a position bit number of position bits to a modulation symbol bit number of modulation symbol bits is two to five.

21. The wireless communication device of claim 19, wherein said means for modifying the subset of tone symbols includes:

i) means for replacing the one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels with a substitute tone symbol when a substitute tone symbol is available; and

ii) means for dropping said one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels from said subset when a substitute tone symbol is not available.

22. The wireless communication device of claim 21, wherein the higher priority channels include a pilot channel and a sector null channel.

23. The wireless communication device of claim 21, further comprising:

means for performing a search of a predetermined set of substitute tone symbols for an available substitute tone symbol.

24. The wireless communication device of claim 23, further comprising:

means for identifying at least one of the substitute tone symbols as a reserved for use by a second sector; and

wherein the performing a search of a predetermined set of substitute tone symbols comprises searching other substitute tone symbols before searching the identified at least one substitute tone symbol.

25. The wireless communication device of claim 19, wherein the modulation symbols are high power modulation symbols, each high power modulation symbol being a modulation symbol that is to be transmitted at least 3 dB above an average per symbol transmission power used to transmit modulation symbols used to communicate traffic channel information.

26. A wireless communication device for communicating information bits in a wireless OFDM communication system, the wireless communication device comprising:

means for dividing the information bits into at least one modulation symbol bit and at least one position bit;

means for identifying modulation symbols based on the at least one modulation symbol bits, said means for identifying modulation symbols including;

i) means for performing a vector matrix multiplication operation on a bit vector u comprising the modulation symbol bits, the matrix multiplication operation including multiplying the bit vector by a matrix G to produce a vector of coded bits, wherein;

27. The wireless communication device of claim 26, further comprising:

means for transmitting each of the quadrature phase shift keying modulation symbols in one tone symbol of the determined subset of tone symbols.

28. A wireless communication device for communicating information bits in a wireless OFDM communication system, the wireless communication device comprising:

a processor configured to;

divide the information bits into at least one modulation symbol bit and at least one position bit;

identify modulation symbols based on the at least one modulation symbol bits;

determine a subset of tone symbols based on the at least one position bits;

determine whether any of the subset of tone symbols is reserved for use by any one of a plurality of higher priority channels;

when it is determined that one of the subset of tone symbols is reserved for use by any one of the plurality of higher priority channels, modify the subset of tone symbols by performing one operation from the group of operations consisting of;

i) a tone symbol replacement operation and ii) a tone symbol dropping operation; and

modulate the modulation symbols to the subset of tone symbols.

29. The wireless communication device of claim 28, wherein the modulation symbols comprise quadrature phase shift keying modulation symbols and wherein a ratio of a position bit number of position bits to a modulation symbol bit number of modulation symbol bits is two to five.

30. The wireless communication device of claim 28, wherein said processor is configured to:

i) replace the one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels with a substitute tone symbol when a substitute tone symbol is available; and

ii) drop said one of the subset of tone symbols in the subset reserved for use by one of the plurality of higher priority channels from said subset when a substitute tone symbol is not available,

as part of being configured to modify the subset of tone symbols.

31. The wireless communication device of claim 30, wherein the higher priority channels include a pilot channel and a sector null channel.

32. The wireless communication device of claim 30, wherein said processor is further configured to:

perform a search of a predetermined set of substitute tone symbols for an available substitute tone symbol.

33. The wireless communication device of claim 32, wherein said processor is further configured to:

identify at least one of the substitute tone symbols as a reserved for use by a second sector; and

wherein the performing a search of a predetermined set of substitute tone symbols comprises searching other substitute tone symbols before searching the identified at least one substitute tone symbol.

34. The wireless communication device of claim 28, wherein the modulation symbols are high power modulation symbols, each high power modulation symbol being a modulation symbol that is to be transmitted at least 3 dB above an average per symbol transmission power used to transmit modulation symbols used to communicate traffic channel information.

37. The wireless communication device of claim 28, further comprising:

a memory device connected to the processor for storing an indicator of the subset of tone symbols.

35. A wireless communication device for communicating information bits in a wireless OFDM communication system, the wireless communication device comprising:

a processor configured to;

divide the information bits into at least one modulation symbol bit and at least one position bit;

identify modulation symbols based on the at least one modulation symbol bits by;

i) performing a vector matrix multiplication operation on a bit vector u comprising the modulation symbol bits, the matrix multiplication operation including multiplying the bit vector by a matrix G to produce a vector of coded bits, wherein;

36. The wireless communication device of claim 35, further comprising:

a transmitter connected to the processor for transmitting each of the quadrature phase shift keying modulation symbols in one tone symbol of the determined subset of tone symbols.

38. A method of demodulating a received signal including a plurality of modulation symbols in a wireless communication system, the method comprising:

receiving the plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment,

identifying a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

calculating at least one position information bit based at least in part on the identified tone symbol set;

determining that at least one of the plurality of modulation symbols received in the segment is a pilot symbol;

identifying a substitute tone symbol in a predetermined substitute tone symbol set that is a subset of the received segment, responsive to the determining that at least one of the plurality of modulation symbols received in the segment is the pilot symbol;

replacing the at least one of the plurality of modulation symbols received in the segment that is the pilot symbol with the modulation symbol received in the substitute tone symbol; and

decoding at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit.

39. The method of claim 38, further comprising:

calculating the total energy of the modulation symbols received in all the tone symbols of each of the plurality of predetermined tone symbol sets;

determining one of the plurality of predetermined tone symbol sets corresponding to the tone symbol set having the maximum total energy; and

calculating at least one position information bit as a function of the determined tone symbol set.

40. The method of claim 38, wherein each of the plurality of predetermined tone symbol sets consists of eight tone symbols.

41. The method of claim 38, wherein there are four predetermined tone symbol sets.

42. A method of demodulating a received signal including a plurality of modulation symbols in a wireless communication system, the method comprising:

receiving the plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment;

identifying a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

calculating at least one position information bit based at least in part on the identified tone symbol set; and

decoding at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit;

wherein the decoding the at least one modulation symbol to determine the at least one modulation symbol information bit comprises;

discarding as erasures between one and five modulation symbols received in the eight tone symbols of the identified tone symbol set; and

decoding at least five modulation information bits from at least three modulation symbols that are not discarded in the identified tone symbol set.

43. A non-transitory computer readable medium embodying computer executable instructions for controlling a wireless communications device in a wireless communication system to perform the steps of:

receiving a plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment;

identifying a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

calculating at least one position information bit based at least in part on the identified tone symbol set;

determining that at least one of the plurality of modulation symbols received in the segment is a pilot symbol;

identifying a substitute tone symbol in a predetermined substitute tone symbol set that is a subset of the received segment, responsive to the determining that at least one of the plurality of modulation symbols received in the segment is the pilot symbol;

replacing the at least one of the plurality of modulation symbols received in the segment that is the pilot symbol with the modulation symbol received in the substitute tone symbol; and

decoding at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit.

44. The non-transitory computer readable medium of claim 43, wherein the computer executable instructions further control the wireless communications device to perform the steps of:

calculating the total energy of the modulation symbols received in all the tone symbols of each of the plurality of predetermined tone symbol sets;

determining one of the plurality of predetermined tone symbol sets corresponding to the tone symbol set having the maximum total energy; and

calculating at least one position information bit as a function of the determined tone symbol set.

45. The non-transitory computer readable medium of claim 43, wherein each of the plurality of predetermined tone symbol sets consists of eight tone symbols.

46. The non-transitory computer readable medium of claim 43, wherein there are four predetermined tone symbol sets.

47. The non-transitory computer readable medium of claim 45, wherein the decoding the at least one modulation symbol to determine the at least one modulation symbol information bit comprises:

discarding as erasures between one and five modulation symbols received in the eight tone symbols of the identified tone symbol set; and

decoding at least five modulation information bits from at least three modulation symbols that are not discarded in the identified tone symbol set.

48. A wireless communication device for demodulating a received signal including a plurality of modulation symbols in a wireless communication system, the wireless communication device comprising:

means for receiving the plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment;

means for identifying a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

means for calculating at least one position information bit based at least in part on the identified tone symbol set;

means for determining that at least one of the plurality of modulation symbols received in the segment is a pilot symbol;

means for identifying a substitute tone symbol in a predetermined substitute tone symbol set that is a subset of the received segment, responsive to the determining that at least one of the plurality of modulation symbols received in the segment is the pilot symbol;

means for replacing the at least one of the plurality of modulation symbols received in the segment that is the pilot symbol with the modulation symbol received in the substitute tone symbol; and

means for decoding at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit.

49. The wireless communication device of claim 48, further comprising:

means for calculating the total energy of the modulation symbols received in all the tone symbols of each of the plurality of predetermined tone symbol sets;

means for determining one of the plurality of predetermined tone symbol sets corresponding to the tone symbol set having the maximum total energy; and

means for calculating at least one position information bit as a function of the determined tone symbol set.

50. The wireless communication device of claim 48, wherein each of the plurality of predetermined tone symbol sets consists of eight tone symbols.

51. The wireless communication device of claim 48, wherein there are four predetermined tone symbol sets.

52. A wireless communication device for demodulating a received signal including a plurality of modulation symbols in a wireless communication system, the wireless communication device comprising:

means for receiving the plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment;

means for identifying a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

means for calculating at least one position information bit based at least in part on the identified tone symbol set; and

means for decoding at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit; and

wherein the means for decoding the at least one modulation symbol to determine the at least one modulation symbol information bit comprises;

means for discarding as erasures between one and five modulation symbols received in eight tone symbols of the identified tone symbol set; and

means for decoding at least five modulation information bits from at least three modulation symbols that are not discarded in the identified tone symbol set.

53. A wireless communication device for demodulating a received signal including a plurality of modulation symbols in a wireless communication system, the wireless communication device comprising:

a processor configured to;

receive the plurality of modulation symbols wherein each modulation symbol is received in a tone symbol of a communication segment;

identify a set of tone symbols from a plurality of predetermined tone symbol sets, wherein each predetermined tone symbol set is a subset of the segment;

calculate at least one position information bit based at least in part on the identified tone symbol set;

determine that at least one of the plurality of modulation symbols received in the segment is a pilot symbol;

identify a substitute tone symbol in a predetermined substitute tone symbol set that is a subset of the received segment, responsive to determining that at least one of the plurality of modulation symbols received in the segment is the pilot symbol;

replace the at least one of the plurality of modulation symbols received in the segment that is the pilot symbol with the modulation symbol received in the substitute tone symbol; and

decode at least one modulation symbol received in the identified set of tone symbols to determine at least one modulation symbol information bit.

54. The wireless communication device of claim 53, wherein the processor is further configured to:

calculate the total energy of the modulation symbols received in all the tone symbols of each of the plurality of predetermined tone symbol sets;

determine one of the plurality of predetermined tone symbol sets corresponding to the tone symbol set having the maximum total energy; and

calculate at least one position information bit as a function of the determined tone symbol set.

55. The wireless communication device of claim 53, wherein each of the plurality of predetermined tone symbol sets consists of eight tone symbols.

56. The wireless communication device of claim 55, wherein the processor is further configured, as part of being configured to decode the at least one modulation symbol, to:

discard as erasures between one and five modulation symbols received in the eight tone symbols of the identified tone symbol set; and

decode at least five modulation information bits from at least three modulation symbols that are not discarded in the identified tone symbol set, to determine the at least one modulation symbol information bit.

57. The wireless communication device of claim 53, wherein there are four predetermined tone symbol sets.

58. The wireless communication device of claim 53, further comprising:

a memory device connected to the processor for storing at least one indicator of at least one of the predetermined tone symbols sets.