Cancellation of interference in a communication system with application to S-CDMA
First Claim
1. An apparatus, comprising:
- a vector de-spreader that is operable to employ a first plurality of codes and a second plurality of codes to de-spread a spread signal that is received from a communication channel, wherein the spread signal includes interference;
a weight computation block that is operable to determine a plurality of complex-valued combining weights using at least one of the spread signal and the interference;
a plurality of scaling blocks that is operable to scale a first plurality of de-spread signal portions of the spread signal, using the plurality of complex-valued combining weights, that is de-spread using the first plurality of codes; and
a linear combiner that is operable selectively to sum the first plurality of de-spread signal portions, after having undergone scaling by the plurality of scaling blocks, and at least one de-spread signal portion of the spread signal that is de-spread using a selected code of the second plurality of codes to perform interference cancellation on the at least one de-spread signal portion of the spread signal that that is de-spread using the selected code of the second plurality of codes.
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Accused Products
Abstract
Cancellation of interference in a communication system with application to S-CDMA. A relatively straight-forward implemented and computationally efficient approach of selecting a predetermined number of unused codes is used to perform weighted linear combination selectively with each of the input spread signals in a multiple access communication system. If desired, the predetermined number of unused codes is always the same in each implementation. Alternatively, the predetermined number of unused codes is selected from within a reordered code matrix using knowledge that is shared between the two ends of a communication system, such as between the CMs and a CMTS. While the context of an S-CDMA communication system having CMs and a CMTS is used, the solution is generally applicable to any communication system that seeks to cancel narrowband interference. Several embodiments are also described that show the generic applicability of the solution across a wide variety of systems.
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Citations
20 Claims
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1. An apparatus, comprising:
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a vector de-spreader that is operable to employ a first plurality of codes and a second plurality of codes to de-spread a spread signal that is received from a communication channel, wherein the spread signal includes interference;
a weight computation block that is operable to determine a plurality of complex-valued combining weights using at least one of the spread signal and the interference;
a plurality of scaling blocks that is operable to scale a first plurality of de-spread signal portions of the spread signal, using the plurality of complex-valued combining weights, that is de-spread using the first plurality of codes; and
a linear combiner that is operable selectively to sum the first plurality of de-spread signal portions, after having undergone scaling by the plurality of scaling blocks, and at least one de-spread signal portion of the spread signal that is de-spread using a selected code of the second plurality of codes to perform interference cancellation on the at least one de-spread signal portion of the spread signal that that is de-spread using the selected code of the second plurality of codes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method comprising:
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employing a first plurality of codes to de-spread a spread signal that is received from an S-CDMA (Synchronous Code Division Multiple Access) communication channel thereby generating a first plurality of de-spread signal portions, wherein the spread signal includes interference;
employing at least one code of a second plurality of codes to de-spread the spread signal that is received from the S-CDMA communication channel thereby generating a second de-spread signal portion;
determining a plurality of complex-valued combining weights;
scaling the first plurality of de-spread signal portions using the plurality of complex-valued combining weights; and
selectively summing the first plurality of de-spread signal portions, after having undergone scaling, and the second de-spread signal portion to perform interference cancellation on the second de-spread signal portion. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method, comprising:
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employing a first plurality of codes to de-spread a spread signal that is received from an S-CDMA (Synchronous Code Division Multiple Access) communication channel thereby generating a first plurality of de-spread signal portions, wherein;
the spread signal includes interference; and
the first plurality of codes is employed to spread a plurality of predetermined symbols thereby generating a portion of the spread signal;
employing at least one code of a second plurality of codes to de-spread the spread signal that is received from the S-CDMA communication channel thereby generating a second de-spread signal portion;
calculating a plurality of complex-valued combining weights using at least one of the spread signal and the interference by employing at least one of least means square processing and least square processing;
scaling the first plurality of de-spread signal portions using the plurality of complex-valued combining weights; and
selectively summing the first plurality of de-spread signal portions, after having undergone scaling, and the second de-spread signal portion to perform interference cancellation on the second de-spread signal portion. - View Dependent Claims (19, 20)
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Specification