CANCELLATION OF INTERFERENCE IN A COMMUNICATION SYSTEM WITH APPLICATION TO S-CDMA
First Claim
1. An apparatus, comprising:
- an equalizer that is operable to;
receive a signal from a communication channel, wherein the signal includes additive white noise and a frequency response of the communication channel includes a null at a frequency; and
equalize the signal using an inverse, zero forcing response that includes a peak at approximately the frequency of the null within the frequency response of the communication channel thereby transforming white noise within the signal to become colored noise located at approximately the frequency; and
a canceller that is operable to perform interference cancellation on the colored noise located at approximately the frequency.
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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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an equalizer that is operable to; receive a signal from a communication channel, wherein the signal includes additive white noise and a frequency response of the communication channel includes a null at a frequency; and equalize the signal using an inverse, zero forcing response that includes a peak at approximately the frequency of the null within the frequency response of the communication channel thereby transforming white noise within the signal to become colored noise located at approximately the frequency; and a canceller that is operable to perform interference cancellation on the colored noise located at approximately the frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus, comprising:
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an equalizer that is operable to; receive a spread signal from a communication channel, wherein the spread signal includes additive white noise and a frequency response of the communication channel includes a null at a frequency; and equalize the signal using an inverse, zero forcing response that includes a peak at approximately the frequency of the null within the frequency response of the communication channel thereby transforming white noise within the signal to become colored noise located at approximately the frequency; and a canceller, that includes a vector de-spreader, a weight computation block, and a linear combiner, that is operable to perform interference cancellation on the colored noise located at approximately the frequency; and
wherein;the vector de-spreader is operable to employ a first plurality of codes and a second plurality of codes to de-spread the spread signal that is received from the equalizer thereby generating a first plurality of de-spread signal portions and a second plurality of de-spread signal portions; the weight computation block is operable to determine a plurality of complex-valued combining weights using at least one portion of the de-spread signal and the colored noise located at approximately the frequency; and the linear combiner is operable to; scale the first plurality of de-spread signal portions using the plurality of complex-valued combining weights; and combine the scaled, plurality of de-spread signal portions with one signal portion that is de-spread using one code of the second plurality of codes thereby performing the interference cancellation on the one signal portion that is de-spread using one code of the second plurality of codes that corresponds to the colored noise located at approximately the frequency; and the apparatus is operable to be implemented within an S-CDMA (Synchronous Code Division Multiple Access) communication system. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method, comprising:
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receiving a spread signal from an S-CDMA (Synchronous Code Division Multiple Access) communication channel, wherein the spread signal includes additive white noise and a frequency response of the communication channel includes a null at a frequency; equalizing the signal using an inverse, zero forcing response that includes a peak at approximately the frequency of the null within the frequency response of the S-CDMA communication channel thereby transforming white noise within the signal to become colored noise located at approximately the frequency; and performing interference cancellation on the colored noise located at approximately the frequency. - View Dependent Claims (18, 19, 20)
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Specification