The problem of non-stationary interference suppression in direct sequence spread-spectrum (DS-SS) systems is considered. The phase of interference is approximated by a polynomial within the considered interval. According to the local polynomial Fourier transform (LPFT) principle, the received signal is dechirped by using the obtained phase approximation and the interference is, in turn, suppres...

Tropospheric scintillation can seriously aaect satellite links operating at Ka-band. The average bit error probability for a multiuser binary direct-sequence spread-spectrum satellite communication network operating under amplitude scintillation is evaluated. Numerical results are presented to illustrate performance comparisons of systems operating under typical scintillation statistics. As in ...

The use of direct sequence spread spectrum (DS-SS) baseband modulation in a mobile communication system have proved to bring many advantages. In this paper a study of the DS-SS modulation and its performances in a multipath fading channel is presented, considering different parameters for the system and communication channel. A RAKE receiver is implemented to achieve diversity over the differen...

Spread spectrum signals have been used for secure communications for several decades [4]. Nowadays, they are also widely used outside the military domain, especially in Code Division Multiple Access (CDMA) systems [2]. Due to their low probability of interception, these signals increase the difficulty of spectrum surveillance. Direct-Sequence Spread Spectrum transmitters (DS-SS) use a periodica...

A microcellular local area network (LAN) for indoor communications is proposed using code division multiple access (CDMA) and DPSK for data modulation. The pseudonoise (PN) codes in the transmitters of the base station are mutually synchronized. For this purpose, sets of Gold code sequences having low cross correlation have been found by an exhaustive computer search. Together with wideband mea...

In this paper, we consider the performance of different coding schemes for direct-sequence spread spectrum (DS-SS) in a nonselective Rician faded channel. The Nordstrom–Robinson (NR) code, a nonlinear code that has large distance for a given rate combined with a trellis code, is examined. A bound is developed on the error probability for this trellis-coded NR (TCNR) code with noncoherent recept...

This paper presents a low-power structure of digital matched filters (DMFs), which is proposed for direct sequence spread spectrum systems. Traditionally, low-power approaches for DMFs are based on either the transposedform structure or the direct-form one. A new hybrid structure that employs the direct-form structure for local addition and the transposed-form structure for global addition is u...

Many techniques for calculating bit-error probabilities (BEPs) of direct-sequence spread-spectrum multiple-access systems (DS-SSMA) have been reported. Among them are the following three techniques: 1) the standard Gaussian approximation; 2) the improved Gaussian approximation; 3) and the simplified improved Gaussian approximation. We extend these techniques to derive the BEPs of multicode DS-S...

We propose robust acquisition schemes for chip time-synchronous direct-sequence spread-spectrum (DS/SS) signals in wide-band pulse jamming. To mitigate the performance degradation due to the impulse-like wide-band jamming signal, the received signal is preprocessed by employing simple order statistic filters. We consider the use of two types of median filtering schemes: a running median filter ...

In deriving the capacity of a direct sequence spread spectrum (DS/SS) multiple access system using the bit error rate (BER) [l], it is assumed that the receiver has already achieved chip synchronization with the spreading sequence used. In the absence of any other timing information [2] the acquisition based capacity, that is the maximum number of users that can be transmitting data while one o...