The technology of Direct Sequence Code Division Multiple Access (DS-CDMA) has been chosen for mobile communication systems because of numerous advantages. A major advantage is that it can provide a better capacity compared to the other possible technologies of multiple access [1]. In a spread spectrum system, the signal bandwidth is increased to a value much larger than is needed to transmit th...

In recent years there has been great interest in using hybrid spread-spectrum (HSS) techniques for commercial applications, particularly in the Smart Grid, in addition to their inherent uses in military communications. This is because HSS can accommodate high data rates with high link integrity, even in the presence of significant multipath effects and interfering signals. A highly useful form ...

Cognitive radio is an encouraging technology for future wireless communication networks. Due to the rapid increase in wireless services, the RF spectrum is going through a scarcity problem. This has forced mobile operators to participate in multimillion dollar auctions to reserve some spectrum resources. Cognitive radio tries to solve this scarcity problem by effectively using the unused portio...

Recently there has been a growing interest in wireless communication in small devices Although Infrared is already widely implemented in small low cost devices there is rapid movement towards wireless communication in the Giga Hertz spectrum which allows for new concepts such as hidden computing The presentation rst describes some of the techniques used in transmitting information wirelessly It...

In the context of spectrum surveillance (non cooperative context), a robust synchronization procedure is presented, in order to estimate the period symbol and the timing o¤set of a direct sequence spread spectrum signal. Experimental results are given to illustrate the performances of the algorithm.

Assume that we are given a watermark (wm) embedding algorithm that performs well against generic benchmark-type attacks that comprise of simple operations that are independent of the algorithm and generally of the input as well. A natural question then is to ask for a nearly perfect cryptanalytic attack for the specific watermarking method. In this paper we present and analyze an attack on a st...

Spread spectrum techniques such as Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping (FH) have been commonly used for anti-jamming wireless communication. However, traditional spread spectrum techniques require that sender and receivers share a common secret in order to agree upon, for example, a common hopping sequence (in FH) or a common spreading code sequence (in DSSS). Such a re...

In this paper, different methods of modulation technique applicable in data transferring system over distribution line carries (DLC) system is investigated. Two type of modulation –analogue and digital – is evaluated completely. Different digital techniques such as direct-sequence spread spectrum (DSSS), Frequency-hopping spread spectrum (FHSS), time-hopping spread spectrum (THSS), and chirp sp...

With the ever-growing advancements in the field of technology, Digital communication systems are becoming increasingly attractive and flexible for a secure form of data communication. Spread Spectrum overcomes the severe levels of interference that are encountered in the transmission of the digital information and rely upon shift register codes. This paper is in accordance with the design of Sp...

Abstruct: Standard spread-spectrum techniques encounter a severe performance loss under channels with large doppler spread. It is shown that the novel spreadspectrum technique, called multi-canier (MC) CDMA, is dual to direct-sequence CDMA. This enables to derive that MC-CDMA is a signalling technique which allows optimum detection under severe doppler spread. The receiver for this is a RAKE re...