MULTIPLE ACCESS INTERFERENCE CANCELLATION METHODS IN SYNCHRONOUS DS-CDMA SYSTEM

Abstract

The appearance of 3G communication standards represented by W-CDMA and CDMA2000 has overcome difficulties of previous systems about subscriber capacity, security, data rate, ... Interference cancellation methods for these systems have been researched carefully. Additive noise has less effect in DS-CDMA because these systems use modern spectrum spread technique because it has been spread in spectrum at receiver. The largest effect to quality of CDMA services is multiple access interference (MAI). MAI cancellation has been improved and processed by cell-shrinking in the previous system when the number of MSs registered into a BS surpasses over a threshold. This paper introduces linear MAI (decorrelating, MMSE) and nonlinear MAI (PIC, SIC) cancellation methods. These are basic MAI methods to improve many more efficient MAI cancellation algorithms. These methods are the application of using many modern detecting techniques to remove MAI in the received signsl significantly based on mathematic transforms and non-linear detecting techniques.