This paper presents a new blind identification method of nonminimum phase FIR systems and an adaptive blind equalization for PAM/QAM inputs without employing higher-order statistics. They are based on the observation that the absolute mean of a second-order white sequence can measure whether the sequence is higher-order white or not. The proposed methods are new alternatives to many higher-order statistics approaches. Some computer simulations show that the absolute mean is exactly estimated and the proposed methods can overcome the disadvantages of the higher-order statistics approaches.

In this paper, we analyze the multiple access interference of a variable processing gain DS/CDMA system and define discrete partial crosscorrelation functions. We also evaluate the bit error rate of the system using Gaussian approximation and bounding technique. Three kinds of spreading codes (long, short, and random codes) are considered in the analysis of the system. It is shown that the bit error rate of a user is not relevant to the processing gain of interfering users: it is relevant only to the processing gain of the user, transmitted powers, PN sequences, and spreading codes. The performance of short codes turns out to be better than that of long and random codes as in other systems.