Browsing by Author "Mostaani, Zohreh"

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    Conference paperPublicationMetadata only
    Gamma-gamma türbülans kanallarında tüm-optik rölelemeli FSO sistemleri için röle seçimi
    (IEEE, 2014) Mostaani, Zohreh; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Mostaani, Zohreh
    Bu bildiride, tüm-optiksel çoklu-röle kablosuz optik haberleşme sistemleri için Gamma-Gamma atmosferik türbülans kanalı varsayımı altında servis dışı kalma başarımı incelenmiştir. Röleler arası katı senkronizasyon ihtiyacından kurtulmak adına, röle seçim tekniginden faydalanılmış ve röleleme aşamasında sadece seçilen bir röle kullanılmıştır. Başarım sonuçları, röle seçiminin tüm rölelerin aktif oldugu işbirliği protokolüne göre belirgin seviyede iyileştirme sağladığını göstermektedir.
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    Outage performance of MIMO free-space optical systems in gamma-gamma fading channels
    (IEEE, 2013) Kazemi, Hossein; Mostaani, Zohreh; Uysal, Murat; Ghassemlooy, Z.; Electrical & Electronics Engineering; UYSAL, Murat; Kazemi, Hossein; Mostaani, Zohreh
    In this paper, we consider a MIMO Free-Space Optical (FSO) communication system over gamma-gamma turbulence channels and derive a closed-form analytical expression for the outage probability taking into account the effects of both the inner scale size of optical channel and the aperture averaging. Our results demonstrate that by increasing the number of transmit and/or receive apertures, the degrading effect of the inner scale size is effectively reduced by extracting the spatial diversity gain of the MIMO scheme. We further provide Monte Carlo simulation results to confirm the validity of the derived expression.
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    Master ThesisPublicationEmbargo
    Performance analysis of multi-relay free space optical communication systems
    (2015-01) Mostaani, Zohreh; Uysal, Murat; Uysal, Murat; Demiroğlu, Cenk; Odabaşoğlu, N.; Department of Electrical and Electronics Engineering; Mostaani, Zohreh
    Free space optical (FSO) communication has attracted a great attention in recent years because of their high bandwidth capacity in unregulated spectrum which makes them a cost-effective and easy-to-install alternative to fiber optics. Moreover they provide high immunity to interference and jamming due to directional and narrow beams. FSO systems are appealing for number of applications including last-mile access, fiber back-up, back-haul for wireless cellular networks, and disaster recovery among others. The major degrading factor in these systems is atmospheric turbulence induced fading particularly for long range links. Relay-assisted FSO systems provide significant performance gains by using the advantage of shorter hops and the fact that fading variance is distance dependent in FSO channels. In this thesis, we investigate the performance of multi-relay FSO systems in various settings. In the first part of thesis, we consider an all-optical relaying system to remove the need for optical -electrical- optical conversions. We explore the benefits of relay selection and investigate its outage performance over Gamma-Gamma distributed turbulence channels. In the second part of thesis, we assume that source is equipped with multiple transmit apertures employing the so-called spatial pulse position amplitude modulation (SPPAM). We investigate an upper bound for bit error rate of this system with multiple parallel relays over log-normal distributed channels.