Direct sequence spread spectrum (DS-SS) technique is widely used in modern telecommunications and it represents the latest advancement in radio control signal protection. One of the most widely used unmanned aerial vehicle (UAV) radio control systems is the binary pulse-position modulated (PPM) control system. In this paper, two structures of rake-like receiver for improvement of DS-SS binary P...

Direct Sequence/Spread-Spectrum (DSSS) signals are characterized by a wide bandwidth and a low-power spectral density. These characteristics make them very robust with respect to the jamming. The Jamming represents one of the main concerns for secure communication and communication in a crowded spectrum. When the jamming to signal power ratio is greater than the Process Gain, even the use of DS...

For a direct-sequence spread-spectrum (DS-SS) system we pose and solve the problem of maximum-likelihood (ML) sequence estimation in the presence of narrowband interference, using the expectation-maximization (EM) algorithm. It is seen that the iterative EM algorithm obtains at each iteration an estimate of the interference which is then subtracted from the data before a new sequence estimate i...

A RAKE receiver accomplishing joint blind multipath diversity combining and PN code timing recovery is proposed for direct-sequence spread-spectrum signaling over a frequency-selective fading channel. In this technique, an improved known modulus adaptive algorithm is exploited to perform multipath diversity combining in the blind mode, while a modified PN code timing recovery technique based on...

The frequency diversity of multicarrier direct-sequence signaling can potentially offer robust performance in frequency-selective channels. This paper focuses on the acquisition of multicarrier signals in channels containing fading and partial-band interference. The maximumlikelihood decision rule for parallel acquisition in frequency-selective fading and partial-band interference is derived. S...

Security has long been a challenging problem in wireless networks, mainly due to its broadcast nature of communication. This opens up simple yet effective measures to thwart useful communications between legitimate radios. Spread spectrum technologies, such as direct sequence spread spectrum (DSSS), have been developed as effective countermeasures against, for example, jamming attacks. This pap...

Multiuser underwater acoustic communication is one of the enabling technologies for the autonomous ocean-sampling network (AOSN). Multiuser communication allows vehicles, moorings, and bottom instruments to interact without human intervention to perform adaptive sampling tasks. In addition, multiuser communication may be used to send data from many autonomous users to one buoy with RF communica...

To accommodate high-speed data transmissions, it may be necessary to substantially reduce the processing gain of a direct-sequence spread-spectrum (DSSS) system. As a result, intersymbol interference effects may become more severe. In this paper, we present a new structure for maximum-likelihood sequence estimation equalization of DSSS signals on a multipath fading channel that performs the fun...