نتایج جستجو برای: مودم ofdm
تعداد نتایج: 10350 فیلتر نتایج به سال:
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...
–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...
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...
In this paper, orthogonal frequency-division multiplexing–code-division multiplexing (OFDM-CDM) is presented and investigated as alternative to conventional OFDM for high rate data transmission. An additional multipath diversity gain can be obtained with OFDM-CDM by spreading each data symbol in frequency and time. The optimum reliability information for the Viterbi decoder is derived for OFDM-...
1. Mrs.Veena M.B. Dr.M.N.ShanmukhaSwamy,“Performance analysis of DWT based OFDM over FFT based OFDM and implementing on FPGA” International Journal of VLSI design & Communication Systems (VLSICS) Vol.2, No.3, September 2011. 2. Deepak Gupta, Vipin B Vats, Kamal K. Garg, “Performance Analysis of DFT-OFDM, DCT-OFDM, and DWT-OFDM Systems in AWGN Channel” International Conference on Wireless and Mo...
در این پایان نامه عملکرد ber سیستم ofdm و سیستم ofdm مبتنی بر ویولت گسسته ((dwt-ofdm در حالت خطی و در حضور تقویت کنندههای غیرخطی قدرت ، با هم مقایسه میشود. مهمترین اِشکال سیستمهای چند کاریری حساسیت بالای آنها نسبت به موارد غیر خطی و آفست فرکانس است. در این رساله همچنین ber سیستم ofdm و dwt-ofdm در حضور آفست فرکانس بررسی میگردد
The Orthogonal Frequency Division Multiplexed (OFDM) system introduced here, termed Interference Suppressing OFDM (IS-OFDM), has the capabilities of suppressing narrow-band interference in wide band wireless applications. The IS-OFDM encodes each transmitted symbol in all frequency bins. Each frequency bin will then “contain” all transmitted symbols which are distinguished and separated from ea...
N -continuous OFDM is a modulation technique that has a lower sidelobe than the original OFDM as a result of the continuous connection with its higher-order derivatives between the OFDM symbols. However, N -continuous OFDM has a high symbol error rate. In the present paper, we improve N -continuous OFDM without increasing the symbol error rate by using a selected mapping technique.
Orthogonal frequency division multiplexing (OFDM) is particularly divided to three varieties. Cyclic prefix OFDM, zero padding OFDM, and time domain synchronous OFDM. Compared to CP OFDM, TDS-OFDM has higher spectral efficiency and faster synchronization. This paper reviewed however efficiently uses the compressive sensing (CS) theory to resolve those problems. During this paper, a noise cancel...
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