Linear suppression of wideband data-like interference in DS/SS communications

In this paper, a linear receiver is proposed and its performance is analyzed for direct-sequence spread-spectrum communications with wideband data-like interference. Two groups of communicators employing generalized random spreading are considered, and the signals are assumed to have harmonically related cyclostationarity periods. First, the output signal-to-interference ratio (SIR) of a general correlation receiver is derived in the frequency domain, and the key system parameters that affect the structure of the interference are identified. Then, a linear interference suppression scheme based on the maximum SIR (MSIR) criterion is proposed, and a receiver structure similar to the cyclic Wiener filter is derived. Numerical results show that the proposed linear MSIR receiver significantly outperforms the conventional correlation receiver by effectively suppressing the wideband data-like interference.

I. Introduction

Direct-Sequence Spread-Spectrum (DS/SS) techniques successfully provide interference immunity to both military and commercial communication systems. with DS/SS, even a conventional correlation receiver that simply despreads the received signal can achieve a certain level of interference resistance characterized by the spreading gain [1], [2]. Since a larger spreading gain can only be obtained at the expense of system bandwidth, various signal processing techniques have been developed to achieve additional interference suppression without expanding the bandwidth [3]–[19].