Systems and methods for parallel signal cancellation Number:7,394,879 from the United States Patent and Trademark Office (PTO) owispatent The present invention provides systems and methods for parallel interference suppression. In one embodiment of the invention, a processing engine is used to substantially cancel a plurality of interfering signals within a received signal. The processing engine includes a plurality of matrix generators that are used to generate matrices, each matrix comprising elements of a unique interfering signal selected for cancellation. The processing engine also includes one or more processors that use the matrices to generate cancellation operators. A plurality of applicators applies the cancellation operators to parallel but not necessarily unique input signals to substantially cancel the interfering signals from the input signals. These input signals may include received signals, interference cancelled signals and/or PN codes. The embodiments disclosed herein may be particularly advantageous to systems employing CDMA (e.g., such as cdmaOne and cdma2000), Wideband CDMA, Broadband CDMA and Global Positioning Systems ("GPS") signals.<H cancellation, parallel, Systems, and, met, 7394879.html, Patent, pto, 7394879

Title: Systems and methods for parallel signal cancellation

Abstract: The present invention provides systems and methods for parallel interference suppression. In one embodiment of the invention, a processing engine is used to substantially cancel a plurality of interfering signals within a received signal. The processing engine includes a plurality of matrix generators that are used to generate matrices, each matrix comprising elements of a unique interfering signal selected for cancellation. The processing engine also includes one or more processors that use the matrices to generate cancellation operators. A plurality of applicators applies the cancellation operators to parallel but not necessarily unique input signals to substantially cancel the interfering signals from the input signals. These input signals may include received signals, interference cancelled signals and/or PN codes. The embodiments disclosed herein may be particularly advantageous to systems employing CDMA (e.g., such as cdmaOne and cdma2000), Wideband CDMA, Broadband CDMA and Global Positioning Systems ("GPS") signals.

Patent Number: 7,394,879 Issued on 07/01/2008 to Narayan, et al.

Inventors: Narayan; Anand P. (Boulder, CO), Thomas; John K. (Erie, CO), Olson; Eric S. (Boulder, CO)
Assignee: Tensorcomm, Inc. (Westminster, CO)

Appl. No.: 10/773,777

Filed: February 6, 2004

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
10763346	Jan., 2004	7039136
10686828	Oct., 2003
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Current U.S. Class: 375/346 ; 375/349

Current International Class: H03D 1/04 (20060101)

Field of Search: 375/148,144,346,348,349

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Primary Examiner: Bayard; Emmanuel
Attorney, Agent or Firm: Narayan; Anand P.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application 60/445,243 (filed Feb. 6, 2003), which is herein incorporated by reference. This application is also a continuation-in-part of U.S. patent application Ser. No. 10/669,954 (filed Sep. 23, 2003; the "'954 application"), Ser. No. 10/686,828 (filed Oct. 15, 2003; the "'828 application"), Ser. No. 10/686,829 (filed Oct. 15, 2003; the "'829 application"), Ser. No. 10/699,360 (filed Oct. 31, 2003; the "'360 application"), Ser. No. 10/294,834 (filed Nov. 15, 2002; now U.S. Pat. No. 7,200,183 the "'834 application"), Ser. No. 10/686,359 (filed Oct. 15, 2003; now U.S. Pat. No. 7,068,706 the "'359 application") and Ser. No. 10/763,346 (filed Jan. 23, 2004 now U.S. Pat. No. 7,039,136; the "'346 application"), which are all hereby incorporated by reference. This application is also related to Ser. No. 09/988,219 (filed Nov. 19, 2001; the "'219 application"), which is hereby incorporated by reference.

Claims

The invention claimed is:

1. A processing engine, comprising: a plurality of matrix generators, wherein each matrix generator is configured for generating a matrix comprising elements of an interfering signal selected for cancellation; a processor communicatively coupled to the matrix generators and configured for generating a cancellation operator from each matrix; and a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying at least one of the cancellation operators to an input signal to substantially cancel at least one of the interfering signals.

2. The processing engine of claim 1, wherein the processing engine is configurable with a receiver and wherein the processing engine further comprises a connection element configured for receiving output signals from the applicators and for selecting received said output signals as inputs to processing fingers of the receiver.

3. The processing engine of claim 2, wherein the connection element comprises a plurality of selectors wherein each selector is configured for receiving one of the output signals and for selecting said one of the output signals as one of the inputs to one of the processing fingers.

4. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Code Division Multiple Access signals as one of the inputs to one of the processing fingers.

5. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Wideband Code Division Multiple Access signals as one of the inputs to one of the, processing fingers.

6. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Global Positioning System signals as one of the inputs to one of the processing fingers.

7. The processing engine of claim 3, wherein the output signals are interference cancelled signals.

8. The processing engine of claim 1, wherein each cancellation operator is a projection operator configured for projecting a selected signal substantially orthogonal to one of the interfering signals.

9. The processing engine of claim 8, wherein the projection operator comprises the form: P.sub.s.sup.195 =I-S(S.sup.TS).sup.-1S.sup.T, where P.sub.s.sup..perp. is the projection operator, I is an identity matrix, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

10. The processing engine of claim 1, wherein each of the cancellation operators comprises the form: y'=y-S(S.sup.TS).sup.-1S.sup.Ty, where y' is an output cancelled signal, y is a received signal, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

11. The processing engine of claim 1, further comprising an interference selector configured for selecting the interfering signals as inputs to the matrix generators.

12. The processing engine of claim 11, wherein the interference selector is further configured for providing on-time interfering PN codes of the interfering signals to the matrix generators.

13. The processing engine of claim 11, wherein the interference selector selects the interfering signals based on a pre-determined criteria selected from a group consisting of amplitude, timing offset, phase and code sequence.

14. A method of canceling interference, comprising: generating a plurality of matrices, each matrix comprising elements of an interference signal selected for cancellation; generating a cancellation operator from each of the matrices; and applying each cancellation operator in parallel to an input signal to substantially cancel at least one of the interference signals.

15. The method of claim 14, wherein generating the cancellation operator comprises generating a projection operator having a form: P.sub.s.sup.195 =I-S(S.sup.TS).sup.-1S.sup.T, where P.sub.s.sup..perp. is the projection operator, I is an identity matrix, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

16. The method of claim 14, wherein applying comprises substantially canceling said one of the interfering signals according to the form: y'=y-S(S.sup.TS).sup.-1S.sup.Ty, where y' is an output cancelled signal, y is a received signal, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

17. The method of claim 14, further comprising selecting the interference signals for input to the matrices.

18. The method of claim 17, further comprising providing on-time interfering PN codes of the interfering signals to the matrices in response to selecting.

19. The method of claim 14, further comprising selecting output signals generated in response to applying, for assignment of the output signals to processing fingers of a receiver.

20. The method of claim 19, further comprising transferring the output signals to the processing fingers in response to selecting said output signals as input signals to the processing fingers.

21. The method of claim 19, wherein the output signals are interference cancelled signals.

22. The method of claim 14, further comprising receiving a Code Division Multiple Access signal.

23. The method of claim 14, further comprising receiving a Wideband Code Division Multiple Access signal.

24. The method of claim 14, further comprising receiving a Global Positioning System signal.

25. A system for canceling interference, comprising: means for generating a plurality of matrices, each matrix comprising elements of an interference signal selected for cancellation; means for generating a cancellation operator from each of the matrices; and means for applying each cancellation operator in parallel to an input signal to substantially cancel at least one of the interference signals.

26. The system of claim 25, wherein the means for generating the cancellation operator comprises means for generating a projection operator having a form: P.sub.s.sup.195 =I-S(S.sup.TS).sup.-1S.sup.T, where P.sub.s.sup.195 is the projection operator, I is an identity matrix, S is one of the matrices and S.sup.T is a transpose of the one of the matrices.

27. The system of claim 25, wherein the means for applying comprises means for substantially canceling said one of the interfering signals according to the form: y'=y-S(S.sup.TS).sup.-1S.sup.Ty, where y' is an output cancelled signal, y is a received signal, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

28. The system of claim 25, further comprising means for selecting the interference signals for input to the matrices.

29. The system of claim 25, further comprising means for providing on-time interfering PN codes of the interfering signals to the matrices in response to selecting.

30. The system of claim 25, further comprising means for selecting output signals generated in response to applying, for assignment of the output signals to processing fingers of a receiver.

31. The system of claim 30, further comprising means for transferring the output signals to the processing fingers in response to selecting said output signals.

32. The system of claim 30, wherein the output signals are interference cancelled signals.

33. The system of claim 25, further comprising means for receiving a Code Division Multiple Access signal.

34. The system of claim 25, further comprising means for receiving a Wideband Code Division Multiple Access signal.

35. The system of claim 25, further comprising means for receiving a Global Positioning System signal.

36. A mobile handset, comprising: a receiver configured for receiving a radio signal; and a processing engine communicatively coupled to the receiver and comprising a plurality of matrix generators, wherein each matrix generator is configured for generating a matrix comprising elements of an interfering signal selected for cancellation, a processor communicatively coupled to the matrix generators and configured for generating a cancellation operator from each matrix, and a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying at least one of the cancellation operators to an input signal to substantially cancel at least one of the interfering signals.

37. The mobile handset of claim 36, wherein the processing engine further comprises a connection element configured for receiving output signals from the applicators and for selecting received said output signals as inputs to processing fingers of the receiver.

38. The mobile handset of claim 37, wherein the connection element comprises a plurality of selectors wherein each selector is configured for receiving one of the output signals and for selecting said one of the output signals as one of the inputs to one of the processing fingers.

39. The mobile handset of claim 38, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Code Division Multiple Access signals as one of the inputs to one of the processing fingers.

40. The mobile handset of claim 38, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Wideband Code Division Multiple Access signals as one of the inputs to one of the processing fingers.

41. The mobile handset of claim 38, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Global Positioning System signals as one of the inputs to one of the processing fingers.

42. The mobile handset of claim 38, wherein the output signals are interference cancelled signals.

43. The mobile handset of claim 36, wherein each cancellation operator is a projection operator configured for projecting a selected signal substantially orthogonal to one of the interfering signals.

44. The mobile handset of claim 43, wherein the projection operator comprises the form: P.sub.s.sup.195 =I-S(S.sup.TS).sup.-1S.sup.T, where P.sub.s.sup..perp. is the projection operator, I is an identity matrix, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

45. The mobile handset of claim 36, wherein each of the cancellation operators comprises the form: y'=y-S(S.sup.TS).sup.-1S.sup.Ty, where y' is an output cancelled signal, y is a received signal, S is one of the matrices and S.sup.T is a transpose of said one of the matrices.

46. The mobile handset of claim 36, further comprising an interference selector configured for selecting the interfering signals as inputs to the matrix generators.

47. The mobile handset of claim 46, wherein the interference selector is further configured for providing on-time interfering PN codes of the interfering signals to the matrix generators.

48. The mobile handset of claim 46, wherein the interference selector selects the interfering signals based on a pre-determined criteria selected from a group consisting of amplitude, timing offset, phase and code sequence.

49. The mobile handset of claim 36, wherein the radio signal comprises a Code Division Multiple Access signal.

50. The mobile handset of claim 36, wherein the radio signal comprises a Wideband Code Division Multiple Access signal.

51. The mobile handset of claim 36, wherein the radio signal comprises a Global Positioning System signal.

Description

BACKGROUND

1. Field of the Invention

The invention generally relates to the field of communications. More specifically the invention is related to interference suppression for use in coded signal communications, such as Code Division Multiple Access ("CDMA") communications.

2. Discussion of the Related Art

Interference in communications obstructs the intended reception of a signal and is a persistent problem. Interference may exist in many forms. In CDMA communications, for example, interference is typically the result of receiving one or more unwanted signals simultaneously with a selected signal. These unwanted signals may disrupt the reception of the selected signal because of mutual interference. This disruption of the selected signal is typical in CDMA telephony systems and may corrupt data retrieval processes of a selected signal.

In CDMA telephony, a communications system typically includes a plurality of "base stations" providing a coverage area within a geographic region. These base stations communicate with mobile telephones and/or other CDMA devices operating within the coverage area. To illustrate, a base station provides a coverage "cell" within the overall communication coverage area maintained by the communications system. While within a particular cell, a mobile telephone, or "handset", can communicate with the base station providing the coverage for that cell. As the mobile telephone moves to the cell of another base station, communications between the mobile telephone and the base station providing the initial cell coverage can be transferred via a "hand off" to the other base station.

Each base station within a CDMA telephony system uses coded signals to communicate with mobile telephones. For example, typical CDMA telephony systems use pseudorandom number (PN) spreading codes, sometimes referred to as "short codes," to encode data signals. These encoded data signals are transmitted to and from mobile telephones to convey digitized voice and/or other forms of communication. PN codes are known to those skilled in the art. The terms coded signals and encoded signals are interchangeably used herein.

To encode the data signals, the base station applies a PN code to the data at a rate faster than that of the data. For example, the PN code is applied to the data such that there are multiple "chips" of the code for any given element of data. Such an application of the PN code is commonly referred to as direct sequence spreading of the data. Chips and their associated chip rates are known to those skilled in the art.

Sometimes, each base station is assigned a particular timing offset of the short code to differentiate between base stations. Mobile telephones may therefore determine the identity of a particular base station based on the timing offset of the short code. Additionally, the data signals are often further encoded with a unique "covering" code. Such covering codes provide "channelization" for a signal that increases the number of unique communication channels. For example, data encoded with a covering code can further differentiate signals thereby improving detection and subsequent processing of a selected signal.

These covering codes are often used in CDMA telephony systems and typically include families of codes that are orthogonal (e.g., Walsh codes) or codes that are substantially orthogonal (e.g. quasi-orthogonal functions ("QOF")). Orthogonal covering codes and QOF covering codes have properties that allow for the differentiation of unwanted signals and are known to those skilled in the art. Walsh codes are also known to those skilled in th