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Alamouti-type space-time block coding is studied for optical wireless communication systems using coherent detection over atmospheric turbulence channels. Atmospheric turbulence-induced fading and phase noise are known to impair the performance of coherent optical wireless systems. Two new Alamouti-type space-time coded architectures are proposed to(More)
A detailed analysis and comparison is carried out for optical wireless communications (OWCs) with coherent and subcarrier-intensity-modulation-based systems, which are the two major implementations for detection-threshold-free operation without irreducible error floors. Error rate performance is studied for communications with binary phase-shift keying,(More)
A coherent multiple-input multiple-output architecture is proposed for optical wireless communications (OWCs) to mitigate atmospheric turbulence effects. Transmitter optical signals operate at distinct carrier frequencies to allow the received optical signals to be separately processed. The accumulated phase noise in each transmission branch can then be(More)
Wireless optical communication systems with coherent detection are analyzed for Gamma-Gamma distributed turbulence channels. In addition to the shot noise, we consider the impacts of both turbulence amplitude fluctuations and phase fluctuations on the error performance. Error rate analyses of predetection and postdetection equal gain combining (EGC) are(More)
Diversity reception can be used over free-space optical links to mitigate atmospheric turbulence effects on system performance. In this paper, we present the error rate analysis for equal gain combining with heterodyne detection in coherent free-space optical communication systems over K-distributed atmospheric turbulence channels. The signal-to-noise ratio(More)
Space-time codes are of great interest for wireless communication systems as they can be used to improve the system performance. For optical wireless communications using coherent detection, atmospheric channels can induce fading as well as phase noise to degrade wireless link performance. In this paper, a space-time coded communication system is studied(More)