Browsing by Author "Safaraliev, Sadi"
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Conference paperPublication Metadata only Effect of LED wiring and cabling topologies on visible light communication channels(IEEE, 2018-01-19) Safaraliev, Sadi; Miramirkhani, Farshad; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Safaraliev, Sadi; Miramirkhani, FarshadVisible light communication (VLC) is an emerging short-range wireless access technology. It involves the dual use of illumination infrastructure for communication purposes and builds upon the principle of modulating light emitting diodes (LEDs) at very high speeds that are not noticeable to the human eye. Although there has been a growing literature on VLC channel modeling, the existing works mainly overlook the effects of wiring and cabling topologies. Wiring topology refers to how LED chips are connected within the luminaire while cabling topology refers to how the luminaires are connected to the communication access point. In this paper, we adopt ray-tracing based VLC channel modeling approach and consider various cabling/wiring topologies. For each topology, we obtain channel impulse responses (CIRs) and quantify the impact of wiring and cabling delays.ArticlePublication Open Access Effect of wiring and cabling topologies on the performance of distributed MIMO OFDM VLC systems(IEEE, 2019) Narmanlıoğlu, Ömer; Kızılırmak, R. Ç.; Miramirkhani, Farshad; Safaraliev, Sadi; Sait, S. M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Narmanlıoğlu, Ömer; Miramirkhani, Farshad; Safaraliev, SadiSince most indoor spaces have multiple luminaires for illumination, for visible light communication (VLC) systems, multiple-input multiple-output (MIMO) communication emerges as a natural solution to improve the data rates and/or the link reliability. The existing works on MIMO VLC systems, however, overlook the characteristics of the lighting infrastructure and the luminaire design, which might have implications for the VLC system design. A luminaire typically consists of multiple LED chips. The wiring topology refers to how the LED chips are connected within the luminaire. The cabling topology, on the other hand, refers to how the luminaires are connected to the communication access point (AP). Based on the type and length of cabling and wiring, significant delays can be introduced, which should be taken into account in channel modeling. In this paper, we adopt the non-sequential ray tracing to model the distributed MIMO VLC channels for various practical wiring and cabling topologies. Based on the developed channel models, we provide a comparative performance analysis of repetition coding (RC), spatial multiplexing (SMUX), and spatial modulation (SMOD) MIMO modes. Our results quantify the effect of wiring/cabling delays and provide insights into the optimized design of lighting infrastructure and luminaires for the support of VLC as an add-on service.Master ThesisPublication Metadata only Lighting design considerations and channel modeling for visible light communications(2019-06-10) Safaraliev, Sadi; Uysal, Murat; Uysal, Murat; Tekin, Ahmet; Baykas, T.; Department of Electrical and Electronics Engineering; Safaraliev, SadiThere has been an extensive work on visible light communication (VLC) mainly due to scarcity in radio frequency (RF) spectrum and urgent need for a new wireless communication system in the near future. VLC considers the dual use of LED luminaires as the light sources for illumination as well as signal sources for wireless communication applications. However, to the best of our knowledge, the existing works mainly overlook lighting design considerations which might have significant effects on the performance of VLC systems. In addition, there is a lack of proper VLC channel models which take into account wiring and cabling topologies. In the first part of this thesis, we discuss some main indoor lighting design considerations and their implications for VLC applications. In particular, we consider some practical cabling topologies of LED luminaires and wiring topologies of LED chips within the luminaires. Based on non-sequential ray tracing, we obtain channel impulse responses (CIRs) and quantify the impact of cabling and wiring delays. In the second part of thesis, we consider outdoor applications of VLC. We first discuss outdoor lighting design considerations and their possible implications on VLC system design. Based on ray-tracing approach, we obtain CIRs for an infrastructure-to-pedestrian (I2P) outdoor VLC scenario. Using these CIRs, we calculate channel DC gain, path loss, root mean square (RMS) delay spread and mean excess delay values.