Software-defined radio architectures for interference cancellation in DS-CDMA systems

Third-generation wireless systems call for strategies that can improve achievable performance and data rates while providing flexibility and affordability. Software-defined radio technology is promising to provide the required flexibility in radio frequency, intermediate frequency, and baseband signal processing stages. Baseband signal processing techniques such as interference cancellation for direct-sequence code-division multiple access systems have the potential to provide the higher performance requirements of 3G systems. With advances in digital signal processor technology, the gap between the complexity of interference cancellation algorithms and available processing speeds is narrowing. However, 3G system requirements are ever pushing the envelope of signal processing algorithms required, including multi-user detection schemes, that are considered to be attractive and viable candidates. WINLAB has been working on an attractive SDR solution, to provide flexibility and handle the processing speeds required of 3G radio receivers. The approach is based on SDR architectures that partition radio receiver processing into two core technologies (field programmable gate arrays and DSP devices). We present a summary of the SDR work at WINLAB that is based on using this mixed signal processing approach for implementation of nonlinear interference cancellation and linear multi-user detection algorithms.