Block detection receiver

• US 6,668,011 B1
• Filed: 06/18/1999
• Issued: 12/23/2003
• Est. Priority Date: 12/21/1998
• Status: Expired due to Term

• Current Assignee: Blackberry Limited
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Li, Bin, Tong, Wen
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Kim, Kevin
• Application Number:
  US09/335,845
• Time in Patent Office: 1,649 Days
• Field of Search: 375/130, 375/140, 375/147, 375/149, 370/209, 370/342, 370/441
• US Class Current: 375/147
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

A method and block detection receiver for detecting codes carried in a received signal processed into blocks of values. The method includes the steps of arranging the blocks into non-overlapping sets of at least two blocks per set; and for each set, executing a code detection operation over combinations of values, each combination containing one value from each block in the set. A single- or dual-maxima metric generator may be used. Preferably, the number of combinations of values is restricted and the values in a combination are weighted. The block detection receiver executes a form of sequence estimator. Accordingly, performance of the receiver is close to that of coherent detection and is much better than that of the conventional receivers which do not consider more than one consecutive block.

Claims

1. A method of detecting codes carried in a received signal processed into blocks of values, each block being associated with a respective time interval of the received signal, the method comprising:

arranging the blocks into non-overlapping sets of at least two blocks per set; and

for each set, executing a code detection operation over combinations of values, each combination containing one value from each block in the set.

2. A method as claimed in claim 1, wherein each combination is associated with a sequence of codes, one code for each block in the set, and wherein the code detection operation comprises, for each set of blocks:

for each combination, summing the values in the combination to produce a summed value;

for each summed value, determining the presence of a characteristic therein;

identifying the combination having a summed value with the strongest presence of said characteristic; and

selecting the sequence of codes associated with the combination so identified.

3. A method as claimed in claim 2, wherein the values and summed values are complex with a modulus, and wherein said characteristic is the square modulus.

4. A method as claimed in claim 2, wherein the values and summed values are complex with a modulus, and wherein said characteristic is a monotonic function of the modulus.

5. A method as claimed in claim 2, wherein each code has an associated index symbol, further comprising:

selecting the index symbols associated with the codes in the selected sequence of codes to generate soft decision data.

6. A method as claimed in claim 5, wherein each code has an associated index symbol, further comprising:

scaling the soft decision data in accordance with the summed value of the combination associated with the selected sequence of codes.

7. A method as claimed in claim 6, further comprising:

deinterleaving the soft decision data; and

decoding the deinterleaved soft decision data into digital traffic data bits.

8. A method as claimed in claim 2, wherein the codes are Walsh codes.

9. A method as claimed in claim 2, wherein the codes are orthogonal codes.

10. A method as claimed in claim 2 for use in a demodulator, wherein said values are transformed values of de-spread samples of the received signal.

11. A method as claimed in claim 1, wherein each combination is associated with a sequence of multi-bit index symbols and wherein the code detection operation comprises, for each set of blocks:

for each combination, summing the values in the combination to produce a summed value;

for each summed value, determining the presence of a characteristic therein; and

for each possible bit position in a multi-bit index symbol;

in a subset of combinations consisting of those combinations whose associated multi-bit index symbol has a logical “

1”

in said bit position, identifying the combination having a summed value with the strongest presence of said characteristic, that combination being a first combination;

in a subset of combinations consisting of those combinations whose associated multi-bit index symbol has a logical “

0”

in said bit position, identifying the combination having a summed value with the strongest presence of said characteristic, that combination being a second combination; and

generating soft decision data based on the multi-bit index symbols and summed values associated with the first and second combination corresponding to each bit position.

12. A method as claimed in claim 11, further comprising:

deinterleaving the soft decision data; and

decoding the deinterleaved soft decision data into digital traffic data bits.

13. A method as claimed in claim 11, wherein the codes are Walsh codes.

14. A method as claimed in claim 11, wherein the codes are orthogonal codes.

15. A method as claimed in claim 11 for use in a demodulator, wherein said values are transformed values of de-spread samples of the received signal.

16. A method as claimed in claim 1, further comprising, between the steps of arranging the blocks and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of values having one value from each block in the set;

wherein the code detection operation is carried out over only the combinations of values in said subset.

17. A method as claimed in claim 16, wherein the values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each value in at least one designated block in the set, determining the square modulus of said value;

selecting only those combinations whose values from a designated block have moduli among the L largest for values in that block.

18. A method as claimed in claim 2, further comprising, between the steps of arranging the blocks and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of values having one value from each block in the set;

wherein the code detection operation is carried out over only the combinations of values in said subset.

19. A method as claimed in claim 18, wherein the values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each value in at least one designated block in the set, determining the square modulus of said value;

selecting only those combinations whose values from a designated block have moduli among the L largest for values in that block.

20. A method as claimed in claim 11, further comprising, between the steps of arranging the blocks and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of values having one value from each block in the set;

wherein the code detection operation is carried out over only the combinations of values in said subset.

21. A method as claimed in claim 20, wherein the values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each value in at least one designated block in the set, determining the square modulus of said value;

selecting only those combinations whose values from a designated block have moduli among the L largest for values in that block.

22. A method as claimed in claim 2, further comprising, prior to the step of summing:

for each combination of values, scaling each value in the combination on the basis of the block from which each value originates.

23. A method as claimed in claim 11, further comprising, prior to the step of summing:

for each combination of values, scaling each value in the combination on the basis of the block from which each value originates.

24. A method as claimed in claim 18, further comprising, prior to the step of summing:

for each combination of values, scaling each value in the combination on the basis of the block from which each value originates.

25. A method as claimed in claim 20, further comprising, prior to the step of summing:

for each combination of values, scaling each value in the combination on the basis of the block from which each value originates.

26. A method of detecting codes carried in a received signal processed into blocks of values, each block being associated with a respective time interval of the received signal, the method comprising:

for each stream of blocks, arranging the blocks into non-overlapping sets of at least two blocks per set, thereby to produce a respective stream of sets of blocks;

combining the values from sets of blocks in different streams to form sets of blocks of combined values; and

for each set of blocks of combined values, executing a code detection operation over combinations of combined values, each combination containing one combined value from each block in the set.

27. A method as claimed in claim 26, wherein each combination is associated with a sequence of codes, one code for each block in the set, and wherein the code detection operation comprises, for each set of blocks:

for each combination, summing the combined values in the combination to produce a summed value;

for each summed value, determining the presence of a characteristic therein;

identifying the combination having a summed value with the strongest presence of said characteristic; and

selecting the sequence of codes associated with the combination so identified.

28. A method as claimed in claim 27, wherein the values, combined values and summed values are complex with a modulus, and wherein said characteristic is the square modulus.

29. A method as claimed in claim 27, wherein the values, combined values and summed values are complex with a modulus, and wherein said characteristic is a monotonic function of the modulus.

30. A method as claimed in claim 27, wherein each code has an associated index symbol, further comprising:

selecting the index symbols associated with the codes in the selected sequence of codes to generate soft decision data.

31. A method as claimed in claim 30, wherein each code has an associated index symbol, further comprising:

scaling the soft decision data in accordance with the summed value of the combination associated with the selected sequence of codes.

32. A method as claimed in claim 31, further comprising:

deinterleaving the soft decision data; and

decoding the deinterleaved soft decision data into digital traffic data bits.

33. A method as claimed in claim 27, wherein the codes are Walsh codes.

34. A method as claimed in claim 27, wherein the codes are orthogonal codes.

35. A method as claimed in claim 27 for use in a demodulator, wherein each stream of blocks of values is associated with a finger and wherein the values are transformed values of de-spread samples of the received signal.

36. A method as claimed in claim 26, wherein each combination is associated with a sequence of multi-bit index symbols and wherein the code detection operation comprises, for each set of blocks:

for each combination, summing the combined values in the combination to produce a summed value;

for each summed value, determining the presence of a characteristic therein; and

for each possible bit position in a multi-bit index symbol;

in a subset of combinations consisting of those combinations whose associated multi-bit index symbol has a logical “

1”

in said bit position, identifying the combination having a summed value with the strongest presence of said characteristic, that combination being a first combination;

in a subset of combinations consisting of those combinations whose associated multi-bit index symbol has a logical “

0”

in said bit position, identifying the combination having a summed value with the strongest presence of said characteristic, that combination being a second combination; and

generating soft decision data based on the multi-bit index symbols and summed values associated with the first and second combination corresponding to each bit position.

37. A method as claimed in claim 36, further comprising:

deinterleaving the soft decision data; and

decoding the deinterleaved soft decision data into digital traffic data bits.

38. A method as claimed in claim 36, wherein the codes are Walsh codes.

39. A method as claimed in claim 36, wherein the codes are orthogonal codes.

40. A method as claimed in claim 36 for use in a demodulator, wherein said values are transformed values of de-spread samples of the received signal.

41. A method as claimed in claim 26, further comprising, between the steps of combining and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of combined values having one combined value from each block in the set;

wherein the code detection operation is carried out over only the combinations of combined values in said subset.

42. A method as claimed in claim 41, wherein the combined values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each combined value in at least one designated block in the set, determining the square modulus of said combined value;

selecting only those combinations whose combined values from a designated block have moduli among the L largest for combined values in that block.

43. A method as claimed in claim 27, further comprising, between the steps of combining and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of combined values having one combined value from each block in the set;

wherein the code detection operation is carried out over only the combinations of combined values in said subset.

44. A method as claimed in claim 43, wherein the combined values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each combined value in at least one designated block in the set, determining the square modulus of said combined value;

selecting only those combinations whose combined values from a designated block have moduli among the L largest for combined values in that block.

45. A method as claimed in claim 36, further comprising, between the steps of combining and executing a code detection operation, the step of:

for each set of blocks, identifying a subset of combinations among all possible combinations of combined values having one combined value from each block in the set;

wherein the code detection operation is carried out over only the combinations of combined values in said subset.

46. A method as claimed in claim 45, wherein the combined values in each block are complex with a modulus and wherein the step of identifying a subset comprises, for each set of blocks:

for each combined value in at least one designated block in the set, determining the square modulus of said combined value;

selecting only those combinations whose combined values from a designated block have moduli among the L largest for combined values in that block.

47. A method as claimed in claim 27, further comprising, prior to the step of summing:

for each combination of combined values, scaling each combined value in the combination on the basis of the blocks from which each combined value is derived.

48. A method as claimed in claim 36, further comprising, prior to the step of summing:

for each combination of combined values, scaling each combined value in the combination on the basis of the blocks from which each combined value is derived.

49. A method as claimed in claim 43, further comprising, prior to the step of summing:

for each combination of combined values, scaling each combined value in the combination on the basis of the blocks from which each combined value is derived.

50. A method as claimed in claim 45, further comprising, prior to the step of summing:

for each combination of combined values, scaling each combined value in the combination on the basis of the blocks from which each combined value is derived.

51. A block detection receiver, comprising:

at least one finger, each finger comprising means for processing a received signal to provide sets of non-overlapping blocks of processed values, each block being associated with a respective time interval of the received signal;

means connected to the fingers, for combining a set of blocks of processed values from each finger into a set of blocks of combined processed values; and

a metric generator connected to the combining means, for executing a code detection operation over combinations of processed values in each set, said combinations having one processed value from each block in the set.

52. A block detection receiver as claimed in claim 51, wherein the metric generator comprises a selection unit operable to identify a subset of combinations among all possible combinations of processed values having one processed value from each block in a set and processing only those combinations so identified.

53. A block detection receiver as claimed in claim 51, wherein the metric generator comprises a weighting unit operable to scale each processed value in a combination of processed values on the basis of the block from which the processed value is taken.

54. A block detection receiver as claimed in claim 52, wherein the metric generator comprises a weighting unit operable to scale each processed value in a combination of processed values on the basis of the block from which the processed value is taken.

56. A block detection receiver as claimed in claim 52, wherein the processing means comprises:

first circuitry connected to the buffer, for summing the values in each combination in each set of blocks to produce a respective summed value and determining, for each said summed value, the presence of a characteristic therein;

second circuitry connected to the first circuitry, for identifying the combination in a set of blocks having a summed value with the strongest presence of said characteristic and selecting the sequence of codes associated with the combination so identified.

57. A block detection receiver as claimed in claim 56, wherein the transformed values and summed values are complex with a modulus, wherein said characteristic is the square modulus and wherein said second circuitry is a single-maxima metric generator.

60. A block detection receiver as claimed in claim 56, wherein the processing means comprises a selection unit operable to identify a subset of combinations among all possible combinations of transformed values having one transformed value from each block in a set and processing only those combinations so identified.

63. A block detection receiver as claimed in claim 56, wherein the processing means comprises a weighting unit operable to scaling each transformed value in a combination on the basis of the block from which said transformed value is taken.

55. A block detection receiver, comprising:

a transformer for performing block-wise correlations between a received signal and a plurality of codes, thereby to generate blocks of transformed values, each block being associated with a respective time interval of the received signal;

a buffer connected to the transformer, for arranging the blocks into a stream of non-overlapping sets of blocks of transformed values of at least two blocks per set, the at least two blocks per set being associated with distinct time intervals of the received signal; and

processing means connected to the buffer, for executing a code detection operation over combinations of transformed values, each combination containing one transformed value from each block in a set.

58. A block detection receiver as claimed in claim 55, wherein the processing means comprises:

a summer connected to the buffer, for adding the values in each combination in a set of blocks to produce respective summed values;

circuitry connected to the summer, for determining the square modulus of each summed value corresponding to a set of blocks; and

a dual-maxima metric generator connected to said circuitry, for generating soft decision data based on the square moduli received from said circuitry.

59. A block detection receiver as claimed in claim 55, wherein the processing means comprises a selection unit operable to identify a subset of combinations among all possible combinations of transformed values having one transformed value from each block in a set and processing only those combinations so identified.

61. A block detection receiver as claimed in claim 58, wherein the processing means comprises a selection unit operable to identify a subset of combinations among all possible combinations of transformed values having one transformed value from each block in a set and processing only those combinations so identified.

62. A block detection receiver as claimed in claim 55, wherein the processing means comprises a weighting unit operable to scaling each transformed value in a combination on the basis of the block from which said transformed value is taken.

64. A block detection receiver as claimed in claim 58, wherein the processing means comprises a weighting unit operable to scaling each transformed value in a combination on the basis of the block from which said transformed value is taken.

65. A block detection receiver, comprising:

a plurality of transformers for performing block-wise correlations between a received signal and a plurality of codes, thereby to generate blocks of transformed values for each transformer;

a plurality of buffers, each buffer connected to a respective transformer, for arranging the blocks received from the respective transformer into a respective stream of non-overlapping sets of blocks of transformed values of at least two blocks per set;

a plurality of energy detectors, each energy detector connected to a respective one of the buffers, for detecting the energy of each transformed value in a set of blocks of transformed values received from the respective buffer and producing a respective set of energy values;

combining means connected to the energy detectors, for combining the energy values from each energy detector into a stream of combined energy values; and

processing means connected to the combining means, for processing the combined energy values and executing a code detection operation over combinations combined energy values, each combination of combined energy values having one combined energy value corresponding to each block in a set.

66. A computer-readable storage medium which, when read by a computer, executes a sequence of steps to detect codes carried in a received signal processed into blocks of values, each block being associated with a respective time intervals of the received signal, the steps comprising:

arranging the blocks into non-overlapping sets of at least two blocks per set; and

for each set, executing a code detection operation over combinations of values, each combination containing one value from each block in the set.

67. A computer-readable storage medium which, when read by a computer, executes a sequence of steps to detect codes carried in a received signal processed into a plurality of streams of blocks of values, each blocks being associated with a respective time interval of the received signal, the steps comprising:

for each stream of blocks, arranging the blocks into non-overlapping sets of at least two blocks per set, thereby to produce a respective stream of sets of blocks;

combining the values from sets of blocks in different streams to form sets of blocks of combined values; and

for each set of blocks of combined values, executing a code detection operation over combinations of combined values, each combination containing one combined value from each block in the set.