DEVELOPMENT OF GRAPHICAL USER INTERFACE FOR MICROWAVE FILTER DESIGN

Microwave filters play a sterling role in wireless communication systems and they are used to discriminate between wanted and unwanted signal frequencies. Designing microwave filter is a long process in going from the given specification through the synthesis and simulation to the final prototype. However, due to the unavailability of synthesized theoretical values of reactive elements in the market, the result may disagree with the expected output. Moreover, the existing software tools cover only conventional filter topologies; modern microwave filter topologies such as Ultra Wideband (UWB) filter are not yet incorporated into these software tools. In addition, they are costly and not easy to us

DEVELOPMENT OF GRAPHICAL USER INTERFACE FOR MICROWAVE FILTER DESIGN

Microwave filters play a sterling role in wireless communication systems and they are used to discriminate between wanted and unwanted signal frequencies. Designing microwave filter is a long process in going from the given specification through the synthesis and simulation to the final prototype. However, due to the unavailability of synthesized theoretical values of reactive elements in the market, the result may disagree with the expected output. Moreover, the existing software tools cover only conventional filter topologies; modern microwave filter topologies such as Ultra Wideband (UWB) filter are not yet incorporated into these software tools. In addition, they are costly and not easy to us

Gelişmiş tek kutuplu optik ortogonal frekans bölmeli çoğullama (eU-OFDM) temelli röle-destekli görünür ışık haberleşmesi (VLC)

Thesis (M.A.)--Özyeğin University, Graduate School of Sciences and Engineering, Department of Electrical and Electronics Engineering, August 2016.Due to spectrum scarcity of the conventional radio frequency (RF) and the higher demand for wireless services, visible light communication (VLC) has emerged as a complementary solution to RF technology for ubiquitous wireless connectivity. In the first part of this thesis, we consider a relay-assisted VLC system in an indoor environment where an intermediate light source cooperates with the main light source through an orthogonal amplify-and-forward (OAF) relaying protocol in order to transmit high-speed data to the destination terminal. The optical channel considered in this scenario is based on the IEEE802.15.7r VLC reference channel model for an office space. The information source (ceiling light) is connected to the backbone network, desk light acts as a relaying terminal and the receiving terminal is a photodetector attached to a computer. All the three network terminals are equipped with signal processing units. The proposed relay-assisted VLC system employs the enhanced unipolar optical orthogonal frequency division multiplexing (eU-OFDM) modulation approach. Our performance results show that the relay-assisted system achieves a significant gain over the direct transmission. In the second part of this thesis, a serial multi-hop VLC network is considered. We evaluate the BER performance analysis of multi-hop VLC links through Monte Carlo simulation and validate the simulation results with their respective theoretical counterparts.Radyo frekansı (RF) spektrumu kablosuz servislere artan ihtiyacı karşılayamaz duruma gelmiş olup tamamlayıcı bir çözüm olarak görünür ışık haberleşmesi (Visible Light Communication – VLC), ortaya çıkmıştır. Tezin ilk kısmında, bir içmekanda çalışan röle-destekli VLC sistemi ele alınmıştır. Sözkonusu sistemde ortogonal yükselt-ve-gönder (amplify-and-forward – OAF) röleleme protokolu kullanılmakta ve bir ara ışık kaynağı ana ışık kaynağına yüksek hızda veri iletimi için yardımcı olmaktadır. Optik kanal modeli olarak ofis senaryoları için önerilmiş IEEE802.15.7r VLC referans kanal modeli kullanılmıştır. Bilgi kaynağı (tavan ışığı) omurga ağına bağlı olup, masa lambası ise röle terminali olarak görev almaktadır ve alıcı terminal bir bilgisayara yerleştirilmiş olan bir fotodetektördür. Üç ağ terminaline de birer sinyal işleme birimi konulmuştur. Önerilen röle-destekli VLC sistemi, gelişmiş tek kutuplu optik ortogonal frekans bölmeli çoğullama (enhanced unipolar optical orthogonal frequency division multiplexing – eU-OFDM) tekniği kullanmaktadır. Başarım sonuçlarımız önerilen röle destekli sistemin, doğrudan iletime göre ciddi ölçüde kazançlar sağladığını göstermektedir. Tezin ikinci kısımında, çok-atlamalı bir VLC ağı gözönüne alınmıştır. Çok atlamalı VLC ağı için bit hata oranı başarımı analizi yapılmış ve Monte Carlo simülasyon sonuçları ile doğrulanmıştır

eU-OFDM based multiple access for visible light communication networks

Due to copyright restrictions, the access to the full text of this article is only available via subscription.In this paper, we propose a novel protocol for cooperative multiple access in visible light communication (VLC) networks. The proposed protocol exploits the features of enhanced unipolar orthogonal frequency division multiplexing (eU-OFDM) scheme in order to enable user terminals to sequentially access the multi-hop network. The signal-to-noise ratios (SNRs) for user terminals within the network are derived and the individual bit-error-rate (BER) expressions are presented. We evaluate the BER performances of each user in the network through Monte Carlo simulation. The theoretical results validates the simulation results

Dual-band gemini-shaped microstrip patch antenna for C-band and X-band applications

Due to copyright restrictions, the access to the full text of this article is only available via subscription.In this paper, a novel single-layer Gemini-shaped patch antenna with dual-band characteristics is presented. The proposed patch antenna, with design operating frequencies of 6.53 GHz and 8.62 GHz, is targeted for applications in C-band and X-band. More importantly, the Gemini-shaped microstrip patch antenna exhibits a theta polarized radiation pattern with gains of 6.036 dBi and 9.556 dBi with corresponding reflection coefficients of -18.69 dB (VSWR = 1.263) and -24.31 dB (VSWR = 1.129) at 6.53 GHz and 8.62 GHz, respectively. The measurements of the fabricated patch antenna corroborate the simulation results obtained in Sonnet Suites version 16.52. This dual-resonance antenna, with comparatively high gain performance, can be easily integrated into systems for satellite and radar communications