نتایج جستجو برای: مودم ofdm

تعداد نتایج: 10350  

2014
A.KISHORE S.CHANDRAKANTH M.IMTHIAZ BASHA

This contribution presents low computational complexity versions of orthogonal frequency division multiplexing (OFDM) modulation scheme for the implementation of clustered-OFDM systems for data transmission in the pass band frequency. Among the proposed schemes, which are named Hermitian symmetric OFDM (HS-OFDM) I and HS-OFDM II, the HS-OFDM II can offer computational complexity reduction in co...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تهران 1379

در این پروژه تلاش شده است با انجام مطالعات لازم در محل یک فراهم گر خدمات اینترنتی، مسائل و مشکلات عدیده مودمهای مورد استفاده برای ارتباط با کاربران شناسایی شود و ضمن ارائه راه حلهایی برای آنها با طراحی و ساخت یک کارت کنترلی که در سرخط مودم قرار می گیرد، وضعیتهای مختلف این خط تشخیص داده شود و مونیتور گردد تا ناظر شبکه بتواند در هر لحظه اطلاع دقیقی از وضعیت خط داشته باشد. بدین ترتیب با تحلیل این ...

Journal: :International Journal of Power Electronics and Drive Systems 2021

In this article, different forms of optical orthogonal frequency division multiplexing (OFDM) were observed which suitable for camera communication (OCC) systems. This research aims to establish the bit error rate (BER) versus signal-to-noise ratio (SNR) OCC system. will focus on systems and design that produces noise clipping but gain SNR as a whole if an optimum factor is chosen. The BER anal...

Journal: :EURASIP J. Wireless Comm. and Networking 2012
Zhenhua Yu Robert J. Baxley G. Tong Zhou

Orthogonal frequency division multiplexing (OFDM) has been considered for visible light communication (VLC) thanks to its ability to boost data rates as well as its robustness against frequency-selective fading channels. A major disadvantage of OFDM is the large dynamic range of its time-domain waveforms, making OFDM vulnerable to nonlinearity of light emitting diodes (LEDs). DC biased optical ...

Journal: :Bulletin of Electrical Engineering and Informatics 2021

Wireless communications became an integrated part of the human life. Fifth generation (5G) is modern communication which provides enhanced mobile broadband (eMBB), ultra reliable low latency (URLLC), and massive machine type (mMTC). Thus, 5G have to provide coverage multi-numerology devices, therefore, modulation access schemes are suggested in literature such as cyclic prefix orthogonal freque...

Journal: :IEEE Communications Letters 2023

The nonlinear distortion introduced by the dead time strongly limits throughput of highly sensitive SPAD-based optical wireless communication (OWC) systems. Optical OFDM can be employed in systems with SPAD arrays to improve spectral efficiency. In this work, a theoretical performance analysis OWC system asymmetrically-clipped (ACO-OFDM) is presented. impact nonlinearity on investigated. additi...

Journal: :Optics letters 2014
Zizheng Cao Henrie P A van den Boom Eduward Tangdiongga Ton Koonen

A novel group of interleaved orthogonal frequency division multiplexing (IL-OFDM) and partial transmission IL-OFDM (PT-IL-OFDM) schemes are proposed for optical coherent detection. In the interleaved operation, the odd (or even) subcarriers of an OFDM symbol are reserved (closed). Such an interleaved arrangement can gain the tolerance toward phase noise induced interchannel interference (PN-ICI...

Journal: :IEEE Communications Surveys and Tutorials 2021

Optical Orthogonal Frequency-Division Multiplexing (O-OFDM) is eminently suitable for mitigating the multi-path and chromatic dispersion in both Visible Light Communications (VLC) Fiber Communications. We commence our discourse by surveying conception historic evolution of O-OFDM designed VLC optical fiber, culminating birth its most flexible design alternative, namely Layered Asymmetrically Cl...

در دهه ی اخیر مخابرات نوری فضای آزاد جذابیت زیادی پیدا کرده است و کاربردهای بالقوه ای برای این تکنولوژی پیشنهاد شده است. از بین مدولاسیون های دیجیتال نظیر MDPIM , DPIM , PPM , OOK که در مخابرات نوری فضای آزاد به کار می روند، DPIM مزیت هایی در زمینه ی ظرفیت انتقال، پهنای باند مورد نیاز، توان مصرفی مورد نیاز و طراحی آن دارد. مدولاسیون DPIM با حذف اسلات های خالی ("صفر") که در هر سمبلPPM بلا استفاد...

Journal: :International Journal of Integrated Engineering 2021

Fifth generation (5G) wireless technology is a new communication system that must meet different complementary needs: the high data rate for mobile services, low energy consumption and long-range connected objects, latency to ensure real-time critical applications and, spectral efficiency improve overall capacity. The waveforms associated signal processing present real challenge in implementati...

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