Multiuser receiver for DS-CDMA signals in multipath channels: an enhanced multisurface method

Area of Science:

• Electrical Engineering
• Telecommunications
• Signal Processing

Background:

• Direct-sequence code-division multiple-access (DS-CDMA) systems face performance degradation in multipath environments.
• Existing multiuser detectors are categorized into linear (low-complexity, poor performance) and nonlinear (high-complexity, good performance).
• Multipath propagation severely impacts the performance of linear detectors by destroying code sequence orthogonality.

Purpose of the Study:

• To propose an Enhanced Multisurface Method (EMSM) for improved multiuser detection in DS-CDMA systems operating in multipath channels.
• To evaluate the performance of EMSM against existing linear and nonlinear multiuser detection schemes.
• To offer a detection scheme with complexity linear to the number of users and near-optimal performance.

Main Methods:

• Developed the Enhanced Multisurface Method (EMSM), a piecewise linear detection scheme.
• Compared EMSM's bit error rate (BER) performance against linear detectors, a nonlinear radial basis function detector, and Verdu's optimal detector.
• Conducted simulations in both synchronous and asynchronous multipath channel conditions.

Main Results:

• EMSM consistently outperformed all evaluated linear multiuser detectors in multipath environments.
• The proposed EMSM achieved bit error rate performance comparable to advanced nonlinear detectors.
• EMSM demonstrated a linear run-time complexity concerning the number of users.

Conclusions:

• The Enhanced Multisurface Method (EMSM) provides a robust and efficient solution for multiuser detection in DS-CDMA systems with multipath interference.
• EMSM represents a significant advancement, bridging the performance gap between linear and nonlinear detectors.
• EMSM is a practical approach for enhancing DS-CDMA system performance in real-world wireless communication scenarios.