Cancellation of interference in a communication system with application to s-cdma

An apparatus, comprising:

• 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.

A method, comprising:

• 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.