Bussgang-zero crossing equalization: An integrated HOS-SOS approach

In this paper, an integrated higher order statistics (HOS) and second order statistics (SOS) based equalization technique is presented as an extension of the Bussgang equalization algorithm. This extension allows the simultan eous taking into account of the statistical knowledge about the data source , as done in the conventional HOS approaches and, in particular, by Buss-ga ng-like equalization algorithms such as super exponential, constant modulus , etc., and the spectral redundancy usually present in pulse-amplitude modu lation (PAM) and quadrature-amplitude modulation (QAM) modulated signals, e xploited by SOS-based approaches. The technique presented here employs a ne w form of SOS equalization that naturally inserts into the Bussgang scheme. It is based on a zero crossing (ZC) property of the received signal when i t is passed through a suitable filter. The novel equalization scheme is pre sented in a Bayesian estimation framework, after illustration of the genera l Bussgang paradigm and of the principles of the ZC approach. From simulate d experiments, it results that the extended Bussgang-ZC equalizer not only outperforms conventional Bussgang equalizers but is also robust to situatio ns where HOS and SOS approaches individually fail.