Electrical Engineering (ABSTRACT) In digital communication systems, several types of impairments may be introduced to the signal. These impairments result in degraded system performance; for example, high bit-error-rate or power penalty. For optical communication systems, in this thesis, these impairments are categorized into four types; that is, thermal noise, shot noise, signal-dependent nois...

Information revolution implies that multimedia networks need high bandwidth real-time communication services. At present, optical fibre is the only transmission medium offering such large bandwidth with low loss communication links. To amplify an optical signal with a conventional repeater, one performs photon to electron conversion, electrical amplification, retiming, pulse shaping, and then e...

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In this paper, a two-dimensional true time delay optical beamforming network (OBFN) has been proposed with sub partitioning capability for 3X3 phased array antenna (PAA) operating frequency in X-Band. The architecture is based on raised cosine apodised chirp fiber Bragg grating (CFBG) and Mach-Zehnder interferometer (MZDI). Compared to unapodised CFBG, apodization drastically reduces the ripple...

In this letter, we extend our investigation of generalized multicarrier direct-sequence code-division multiple access by considering two additional types of chip waveforms, namely, the time-domain half-sine and raised-cosine chip waveforms, in addition to the rectangular chip waveform. A range of closed-form equations are provided for quantifying the effect of both the multipath interference an...

This paper summarizes the main results of an early investigation on desirable signal structures for the European &Galileo' civil satellite navigation system. Stemming from the requirements for increased accuracy, reduced time-to-"rst-"x and integrity information provision, the report describes the logical steps and the related numerical results leading to a novel &Galileo' signal de"nition. Alt...

We describe a method for local time-adaptation of the spectrogram of audio signals: it is based on the decomposition of a signal within a Gabor multi-frame of raised cosine windows through the STFT operator. The sparsity of the analyses in every single frame of the multiframe is evaluated through the Rényi entropies measures. We give an analytical expression for the entropy of the spectrogram o...

We derive here a simple and accurate theoretical method for computing the bit-error-probability (BEP) of a direct-sequence spread spectrum (DS-SS) receiver using maximum ratio combiner (MRC), in the presence of code synchronization errors, root raised cosine (RRC) pulse shaping, and Rayleigh fading channels with correlated paths. Theoretical BEP curves with QPSK modulation are validated by link...

In this paper, the effects of Bragg scattering on ultrawideband (UWB) signal transmission from periodic surfaces are reported. First, the frequency dispersive property of Bragg scattering is theoretically and experimentally confirmed. Next, the transfer function of both specular path and Bragg scattering are extracted. Then direct sequence UWB (DS-UWB) transmission simulations are conducted by ...