نتایج جستجو برای: ofdm

تعداد نتایج: 10315  

Journal: :CoRR 2017
Hirofumi Tsuda Ken Umeno

Orthogonal Frequency Division Multiplexing (OFDM) systems have been widely used as a communication system. In OFDM systems, there are two main problems. One of them is that OFDM signals have high Peak-to-Average Power Ratio (PAPR). The other problem is that OFDM signals have large side-lobes. In particular, to reduce side-lobes, UniversalFiltered OFDM (UF-OFDM) systems have been proposed. In th...

2012
K. Dhuness B. T. Maharaj

A method called offset modulation (OM-OFDM) is proposed to control the peak-to-average power ratio (PAPR) of an OFDM signal. The authors demonstrate the significant modulation, structural and performance differences between an OM-OFDM and CE-OFDM method. The OM-OFDM method in addition is able to accurately control the PAPR of a transmission for a targeted BER, which is currently not possible wi...

2013
Archana Ogale Shubhangi Chaudhary Anil J Patil

Multiple Transmit and receive antenna are now popularly used to form multiple input, multiple output (MIMO) channels to increase the capacity as well as to reduce the Bit Error Rate (BER). This paper describes the performance of Hybrid MIMO-OFDM (Orthogonal Frequency Division Multiplexing) models, which are developed & analyzed in Matlab ® Simulink. In this study 2×2 STBC-OFDM and 2×2 SM-OFDM s...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه بیرجند - دانشکده برق و کامپیوتر 1391

با پدیدار شدن تکنولوژی های جدید مخابراتی و با افزایش تعداد سیستم های بی سیم، طیف رادیویی هر روز کمیاب می شود. مطالعات نشان می دهد که رنج وسیعی از طیف به صورت بهینه استفاده نمی شود. از این رو، در سال های اخیر شبکه های رادیو شناختگر با هدف استفاده ی بهینه ازطیف فرکانسی در زمان و مکان به طور گسترده ای مورد توجه قرار گرفته اند. در این شبکه ها طراحی تکنیک های لایه فیزیکی، به دلیل این که کاربر ثانوی...

2013
Prakash Shanmuga priyan

In this paper, the high spectral efficiency of a transmission scheme called Time frequency training (TFT) Orthogonal frequency division multiplexing (OFDM) using MIMO system is proposed. The time frequency joint channel estimation for TFT-OFDM utilizes the time-domain training sequence without interference cancellation to merely acquire the time delay profile of the channel, while the path coef...

2010
V. K. Dwivedi S. Tripathi V. S. Tripathi R. Tripathi S. Tiwari

High peak-to-average power ratio (PAPR) of the transmit signal is a major drawback of multicarrier (MC) transmission such as orthogonal frequency division multiplexing (OFDM) system. This paper presents a novel Reed-Solomon (RS) codes based MC transmission scheme for reduction of PAPR called RS Turbo coded OFDM system. The reduction of PAPR of OFDM signal is obtained through a proper selection ...

2017
Sher Ali Cheema Jianshu Zhang Mario Huemer Martin Haardt

Unique word orthogonal frequency division multiplexing (UW-OFDM) is a new signaling concept which has better spectral properties and also a superior bit error ratio (BER) performance over conventional cyclic prefix (CP) based OFDM. In UW-OFDM, the CPs are replaced by deterministic sequences, the so-called unique words (UWs). So far, the performance of UW-OFDM has been well investigated for sing...

2012
S. Venkateswara Rao

–One of the biggest drawbacks of OFDM is its high peak to average power ratio (PAPR). High PAPR of OFDM makes it unusable in non-linear systems. So the clipping signals scheme is one useful and simple method to reduce the PAR. This paper presents a new receive algorithm called MIMO CI-OFDM has been implemented. From the simulation results, it is shown that MIMO SFBC CI-OFDM reduces PAPR signifi...

نسبت توان اوج به متوسط (PAPR) بالا یک عیب مهم سامانه MIMO-OFDM شناخته می‌شود. PAPR بالا در فرستنده ممکن است تقویت‌کننده را به اشباع ببرد و به اعوجاج غیرخطی به دلیل عناصر غیرخطی بیانجامد. همچنین می‌تواند پیچیدگی مبدل‌های دیجیتال به آنالوگ را افزایش دهد. این مقاله یک روش کاهش PAPR برای سامانه MIMO-OFDM پیشنهاد می‌کند. ایده اصلی، تولید چندین سیگنال نامزد حاوی اطلاعات یکسان و ارسال سیگنال دارای کمت...

2014
N. Manikanda Devarajan

The orthogonal frequency division multiplexing is used in wireless communication due to high data rate. OFDM are robustness against multi-path fading, frequency selective fading, and narrow band interference. Wavelet analysis has strong advantages over fourier transform and also allows time-frequency domain operation with flexibility. Wavelet is applied in various fields of wireless communicati...

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