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This paper presents an improvement for a bit error rate (BER) performance in a free-space optical communication system over log-normal fading channel and misalignment effect, by using single-input multiple-output (SIMO) technique with maximal ratio combining. Differential phase shift keying with subcarrier intensity modulation is applied. The BER closed-form expression is obtained and compared to...
In general, a free space optical (FSO) communication system is prone to three main impairments, 1) atmospheric turbulence induced fading, 2) additive noise, and 3) the random radial displacement of optical beam. The commonly adopted statistical models for these random impairments are Gamma-Gamma distribution, Gaussian distribution, and the Rayleigh distribution, respectively. Considering the aforementioned...
In this paper, average bit error rate (BER) and outage probability are analysed in the free-space optical (FSO) system employing subcarrier intensity modulation (SIM) with differential phase shift keying (DPSK). The FSO channel is described by the lognormal atmospheric turbulence and the pointing error effects. Closed-form analytical expressions for the average BER and outage probability are proposed...
We propose spatial pulse position amplitude modulation (SPPAM) as a novel optical signaling scheme with the capability of having higher power and spectral efficiencies than those of conventional optical modulation techniques. We evaluate the performance of SPPAM in free space optical (FSO) communication systems over weak-to-moderate and moderate-to-strong atmospheric turbulence channels and provide...
In this paper, we propose a new probability distribution function which accurately describes turbulence-induced fading under a wide range of turbulence conditions. The proposed model, termed Double GG distribution, is based on a doubly stochastic theory of scintillation and developed via the product of two Generalized Gamma (GG) distributions. The proposed Double GG distribution generalizes many existing...
Free space optical communications have potential applications in the future global communication network. However, performance of free space optical communication is degraded by atmospheric turbulence. In this paper, we derive closed-form expressions of outage probability for the cases when the scintillation is lognormal probability ditribution over weak atmospheric turbulence channels and gamma-gamma...
Airborne and space-borne imaging systems are often limited in resolution by image degradation resulting from mechanical vibrations during image exposures. A new image stabilization method using digital motion estimation and micro-mechanical compensation is presented. Motion estimation is accomplished by an auxiliary high-speed camera using modified real-time digital image stabilization (DIS) algorithm...
Accelerated high level phase contrast theory is established. Global design adaptive concept, integrated principle, system strategy, spatiotemporal characteristics simulation and evaluation is studied. Accelerated system integrated technique, especially on optical design and modeling, is achieved.
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