Processing for improved performance and reduced pilot

• US 6,516,022 B2
• Filed: 01/11/2002
• Issued: 02/04/2003
• Est. Priority Date: 05/14/1998
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Jacques, Alexander M., Mesecher, David K., Özlütürk, Fatih M.
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Tran, Khai
• Application Number:
  US10/043,850
• Publication Number:
  US 20020067760A1
• Time in Patent Office: 389 Days
• Field of Search: 375/152, 375/130, 375/147, 375/150, 375/376, 375/341, 375/316, 375/342, 375/320, 375/335, 375/441
• US Class Current: 375/152
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The present invention is a user equipment for carrier offset recovery during reception of a communication signal over an air interface using a plurality of channels in a pilot signal. The user equipment comprises an adaptive match filter for producing a filtered signal using a weighting signal, a rake receiver for producing a filter weighting signal, and a means for defining the filter weighting signal with a correction signal. A channel despreader is also included in the user equipment for despreading the filtered signal using a pseudo-noise signal for a selected channel to produce a despread channel signal of the selected channel. A pilot channel despreader is coupled to the adaptive match filter output for despreading the filter signal using a pseudo-noise signal generated for the pilot channel, producing a despread pilot signal of the pilot channel. A hard decision processor, associated with a complex conjugate processor, is also included in the user equipment for producing the correction signal. A phase lock loop, which uses the despread pilot signal, produces a phase correction signal, which is applied to produce phase corrected channel signals.

Claims

1. A user equipment (UE) for carrier-offset recovery during reception of a communication signal over an air interface using a plurality of channels and a pilot signal, comprising:

an adaptive matched filter for receiving demodulated communication signals producing a filtered signal by using a weighting signal;

a rake receiver for receiving the demodulated communication signals and a pseudo-noise signal generated for a selected channel and producing a filter weighting signal;

means for defining the filter weighting signal with a correction signal, said correction signal to produce the weighting signal used by said adaptive matched filter;

a channel despreader for said selected channel coupled to said adaptive matched filter output for despreading said filtered signal using the pseudo-noise signal generated for said selected channel to produce a despread channel signal of said selected channel;

a pilot channel despreader for a pilot channel coupled to said adaptive matched filter output for despreading said filtered signal using a pseudo-noise signal generated for said pilot channel to produce a despread pilot signal of said pilot channel;

a hard decision processor in association with a complex conjugate processor for receiving the despread channel signal of said selected channel and producing said correction signal; and

a phase-locked loop utilizing at least said despread pilot signal for producing a phase correction signal which is applied to produce phase-corrected channel signals.

2. The UE according to claim 1 further comprising a plurality of channel despreaders, each coupled to said adaptive matched filter output for despreading said filtered signal each using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

3. The UE according to claim 2 wherein the number of channel despreaders is three.

4. The UE according to claim 2 wherein said phase-locked loop phase correction signal is at a chip level and is applied to said demodulated communication signals.

5. The UE according to claim 2 wherein each of the plurality of channels is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data, said hard decision processor compares each despread channel signal symbol to one of four possible quadrature constellation points and assigns each of said symbols to a nearest constellation point, and said complex conjugate processor derotates each of said symbols by determining a complex conjugate of each of said assigned points to produce said correction signal.

6. The UE according to claim 2 wherein said phase-locked loop further comprises a plurality of inputs corresponding with said plurality of channel despreaders.

7. The UE according to claim 6 wherein said phase-locked loop further comprises:

a hard decision processor in association with said complex conjugate processor with a local feedback loop for each of said corresponding channel despreader inputs to produce an error estimate signal for a respective channel signal;

each said error estimate signal and said despreader pilot signal coupled to an inverse tangent processor to produce a corresponding phase correction signal; and

said respective channel phase correction signal and pilot phase correction signal coupled to a maximum likelihood combiner producing a combination correction signal coupled to an integrator to produce said phase correction signal.

8. The UE according to claim 7 wherein the number of channel despreaders is three.

9. The UE according to claim 1 wherein said phase-locked loop phase correction signal is at a symbol level and is applied to said filter weighting signal and to said despread channel signals of said channel and pilot channel despreaders.

10. The UE according to claim 9 further comprising a plurality of channel despreaders, each coupled to said adaptive matched filter output for despreading said filtered signal using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

11. The UE according to claim 10 wherein the number of channel despreaders is three.

12. The UE according to claim 10 wherein said phase-locked loop further comprises a plurality of signal inputs corresponding with said plurality of channel despreaders.

13. The UE according to claim 12 wherein said phase-locked loop further comprises:

a hard decision processor in association with a complex conjugate processor with a local feedback loop for each of said plurality of signal inputs, each producing an error estimate for a respective channel signal;

each of said channel error estimates and said despreader pilot signal coupled to an inverse tangent processor outputting a channel phase correction signal; and

said channel and pilot phase correction signals coupled to a maximum likelihood combiner producing a combination correction signal coupled to an integrator to produce said phase correction signal.

14. The UE according to claim 13 wherein the number of channel despreaders is three.

15. A base station for carrier-offset recovery during reception of a communication signal over an air interface using a plurality of channels and a pilot signal, the receiver comprising:

an adaptive matched filter for receiving demodulated communication signals producing a filtered signal by using a weighting signal;

a rake receiver for receiving the demodulated communication signals and a pseudo-noise signal generated for a selected channel and producing a filter weighting signal;

means for defining the filter weighting signal with a correction signal, said correction signal to produce the weighting signal used by said adaptive matched filter;

a channel despreader for said selected channel coupled to said adaptive matched filter output for despreading said filtered signal using the pseudo-noise signal generated for said selected channel to produce a despread channel signal of said selected channel;

a pilot channel despreader for a pilot channel coupled to said adaptive matched filter output for despreading said filtered signal using a pseudo-noise signal generated for said pilot channel to produce a despread pilot signal of said pilot channel;

a hard decision processor in association with a complex conjugate processor for receiving the despread channel signal of said selected channel and producing said correction signal; and

a phase-locked loop utilizing at least said despread pilot signal for producing a phase correction signal which is applied to produce phase-corrected channel signals.

16. The base station according to claim 15 further comprising a plurality of channel despreaders, each coupled to said adaptive matched filter output for despreading said filtered signal each using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

17. The base station according to claim 16 wherein the number of channel despreaders is three.

18. The base station according to claim 16 wherein said phase-locked loop phase correction signal is at a chip level and is applied to said demodulated communication signals.

19. The base station according to claim 16 wherein each of the plurality of channels is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data, said hard decision processor compares each despread channel signal symbol to one of four possible quadrature constellation points and assigns each of said symbols to a nearest constellation point, and said complex conjugate processor derotates each of said symbols by determining a complex conjugate of each of said assigned points to produce said correction signal.

20. The base station according to claim 16 wherein said phase-locked loop further comprises a plurality of inputs corresponding with said plurality of channel despreaders.

21. The base station according to claim 20 wherein said phase-locked loop further comprises:

a hard decision processor in association with said complex conjugate processor with a local feedback loop for each of said corresponding channel despreader inputs to produce an error estimate signal for a respective channel signal;

each said error estimate signal and said despreader pilot signal coupled to an inverse tangent processor to produce a corresponding phase correction signal; and

said respective channel phase correction signal and pilot phase correction signal coupled to a maximum likelihood combiner producing a combination correction signal coupled to an integrator to produce said phase correction signal.

22. The base station according to claim 21 wherein the number of channel despreaders is three.

23. The base station according to claim 15 wherein said phase-locked loop phase correction signal is at a symbol level and is applied to said filter weighting signal and to said despread channel signals of said channel and pilot channel despreaders.

24. The base station according to claim 23 further comprising a plurality of channel despreaders, each coupled to said adaptive matched filter output for despreading said filtered signal using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

25. The base station according to claim 24 wherein the number of channel despreaders is three.

26. The base station according to claim 24 wherein said phase-locked loop further comprises a plurality of signal inputs corresponding with said plurality of channel despreaders.

27. The base station according to claim 26 wherein said phase-locked loop further comprises:

a hard decision processor in association with a complex conjugate processor with a local feedback loop for each of said plurality of signal inputs, each producing an error estimate for a respective channel signal;

each of said channel error estimates and said despreader pilot signal coupled to an inverse tangent processor outputting a channel phase correction signal; and

said channel and pilot phase correction signals coupled to a maximum likelihood combiner producing a combination correction signal coupled to an integrator to produce said phase correction signal.

28. The base station according to claim 27 wherein the number of channel despreaders is three.

29. A user equipment (UE) for carrier-offset recovery during reception of a communication signal over an air interface using a plurality of channels and a pilot signal, comprising:

a means for receiving demodulated communication signals and producing a filtered signal by using a weighting signal;

a means for receiving the demodulated communication signals and a pseudo-noise signal generated for a selected channel and producing a filter weighting signal;

means for defining the filter weighting signal with a correction signal, said correction signal to produce the weighting signal used by said adaptive matched filter;

a channel despreading means for said selected channel, coupled to said means for producing the filtered signal output, for despreading said filtered signal using the pseudo-noise signal generated for said selected channel to produce a despread channel signal of said selected channel;

a pilot channel despreading means for a pilot channel, coupled to said means for producing the filtered signal output, for despreading said filtered signal using a pseudo-noise signal generated for said pilot channel to produce a despread pilot signal of said pilot channel;

means for receiving the despread channel signal of said selected channel and producing said correction signal; and

means for producing a phase correction signal utilizing at least said despread pilot signal, which is applied to produce phase-corrected channel signals.

30. The UE according to claim 29 further comprising a plurality of channel despreading means, each coupled to said means for producing the filtered signal output, for despreading said filtered signal each using an associated pseudo-noise signal generating means to produce a plurality of despread channel signals.

31. The UE according to claim 30 wherein the number of channel despreading means is three.

32. The UE according to claim 30 wherein said phase correction signal is at a chip level and is applied to said demodulated communication signals.

33. The UE according to claim 30 wherein each of the plurality of channels is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data.

34. The UE according to claim 33 wherein said means for producing said connection signal includes:

a decision means for comparing each despread channel signal symbol to one of four possible quadrature constellation points and assigning each of said symbols to a nearest constellation point; and

a processing means for derotating each of said symbols by determining a complex conjugate of each of said assigned points to produce said correction signal.

35. The UE according to claim 30 wherein said means for producing said phase correction signal comprises a plurality of inputs corresponding with said plurality of channel despreading means.

36. The UE according to claim 35 wherein said means for producing said phase correction signal further comprises:

a decision means in association with a processing means with a local feedback loop for each of said corresponding channel despreading means inputs to produce an error estimate signal for a respective channel signal;

each said error estimate signal and said despreader pilot signal coupled to an inverse tangent processing means to produce a corresponding phase correction signal; and

said respective channel phase correction signal and pilot phase correction signal coupled to a combining means producing a combination correction signal coupled to an integrating means to produce said phase correction signal.

37. The UE according to claim 36 wherein the number of channel despreading means is three.

38. The UE according to claim 29 wherein said phase correction signal is at a symbol level and is applied to said filter weighting signal and to said despread channel signals of said channel and pilot channel despreading means.

39. The UE according to claim 38 further comprising a plurality of channel despreading means, each coupled to said means for producing the filtered signal output for despreading said filtered signal using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

40. The UE according to claim 39 wherein the number of channel despreading means is three.

41. The UE according to claim 39 wherein said means for producing the phase correction signal further comprises a plurality of signal inputs corresponding with said plurality of channel despreading means.

42. The UE according to claim 41 wherein said means for producing the phase correction signal further comprises:

a decision means in association with a processing means with a local feedback loop for each of said plurality of signal inputs, each producing an error estimate for a respective channel signal;

each of said channel error estimates and said despreader pilot signal coupled to an inverse tangent processing means outputting a channel phase correction signal; and

said channel and pilot phase correction signals coupled to a maximum likelihood combiner producing a combining means correction signal coupled to an integrating means to produce said phase correction signal.

43. The UE according to claim 42 wherein the number of channel despreading means is three.

44. A base station for carrier-offset recovery during reception of a communication signal over an air interface using a plurality of channels and a pilot signal, comprising:

a means for receiving demodulated communication signals and producing a filtered signal by using a weighting signal;

a means for receiving the demodulated communication signals and a pseudo-noise signal generated for a selected channel and producing a filter weighting signal;

means for defining the filter weighting signal with a correction signal, said correction signal to produce the weighting signal used by said adaptive matched filter;

a channel despreading means for said selected channel, coupled to said means for producing the filtered signal output, for despreading said filtered signal using the pseudo-noise signal generated for said selected channel to produce a despread channel signal of said selected channel;

a pilot channel despreading means for a pilot channel, coupled to said means for producing the filtered signal output, for despreading said filtered signal using a pseudo-noise signal generated for said pilot channel to produce a despread pilot signal of said pilot channel;

means for receiving the despread channel signal of said selected channel and producing said correction signal; and

means for producing a phase correction signal utilizing at least said despread pilot signal, which is applied to produce phase-corrected channel signals.

45. The base station according to claim 44 further comprising a plurality of channel despreading means, each coupled to said means for producing the filtered signal output, for despreading said filtered signal each using an associated pseudo-noise signal generating means to produce a plurality of despread channel signals.

46. The base station according to claim 45 wherein the number of channel despreading means is three.

47. The base station according to claim 45 wherein said means for producing the phase correction signal is at a chip level and is applied to said demodulated communication signals.

48. The base station according to claim 45 wherein each of the plurality of channels is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data.

49. The base station according to claim 48 wherein said means for producing said connection signal includes:

a decision means for comparing each despread channel signal symbol to one of four possible quadrature constellation points and assigning each of said symbols to a nearest constellation point; and

a processing means for derotating each of said symbols by determining a complex conjugate of each of said assigned points to produce said correction signal.

50. The base station according to claim 45 wherein said means for producing said phase correction signal comprises a plurality of inputs corresponding with said plurality of channel despreading means.

51. The base station according to claim 50 wherein said means for producing said phase correction signal further comprises:

a decision means in association with a processing means with a local feedback loop for each of said corresponding channel despreading means inputs to produce an error estimate signal for a respective channel signal;

each said error estimate signal and said despreader pilot signal coupled to an inverse tangent processing means to produce a corresponding phase correction signal; and

said respective channel phase correction signal and pilot phase correction signal coupled to a combining means producing a combination correction signal coupled to an integrating means to produce said phase correction signal.

52. The base station according to claim 51 wherein the number of channel despreading means is three.

53. The base station according to claim 44 wherein said phase correction signal is at a symbol level and is applied to said filter weighting signal and to said despread channel signals of said channel and pilot channel despreading means.

54. The base station according to claim 53 further comprising a plurality of channel despreading means, each coupled to said means for producing the filtered signal output for despreading said filtered signal using an associated pseudo-noise signal generator to produce a plurality of despread channel signals.

55. The base station according to claim 54 wherein the number of channel despreading means is three.

56. The base station according to claim 54 wherein said means for producing the phase correction signal further comprises a plurality of signal inputs corresponding with said plurality of channel despreading means.

57. The base station according to claim 56 wherein said means for producing the phase correction signal further comprises:

a decision means in association with a processing means with a local feedback loop for each of said plurality of signal inputs, each producing an error estimate for a respective channel signal;

each of said channel error estimates and said despreader pilot signal coupled to an inverse tangent processing means outputting a channel phase correction signal; and

said channel and pilot phase correction signals coupled to a maximum likelihood combiner producing a combining means correction signal coupled to an integrating means to produce said phase correction signal.

58. The base station according to claim 57 wherein the number of channel despreading means is three.