نتایج جستجو برای: ofdm
تعداد نتایج: 10315 فیلتر نتایج به سال:
Orthogonal frequency division multiplexing (OFDM) is used in order to provide immunity against very hostile multipath channels in many modern communication systems.. The OFDM technique divides the total available frequency bandwidth into several narrow bands. In conventional OFDM, FFT algorithm is used to provide orthogonal subcarriers. Intersymbol interference (ISI) and intercarrier interferen...
This paper investigates the Multi-band OFDM (MB-OFDM) based physical (PHY) layer proposal for IEEE 802.15.3a working group on short-range high data-rate Ultra-wide-Band (UWB) communications. An overview of the MB-OFDM PHY layer architecture with its various parameters is presented and the optimal choice of critical parameters is discussed. Next, we derive the theoretical un-coded Bit Error Rate...
orthogonal frequency division multiplexing (ofdm) has become a promising method for many wireless communication applications. however, one main drawback of ofdm systems is the high peak-to-average power ratio (papr). selected mapping (slm) is a well-known technique to decrease the problem of high papr in ofdm systems. in this method, transmitter is obliged to send some bits named side informati...
یک روش جدید و مؤثر پهنای باند، برای انجام در مدولاسیون تقسیمات چندگانه فرکانس متعامد (OFDM)، روی کانالهای نوری IM/DD (آشکارسازی مستقیم شدت نور مدوله شده)، OFDM نوری تجزیه طیفی (SFO-OFDM) است. در اینجا نشان میدهیم که شرایط لازم و کافی برای سیگنال پریودیک باند محدود برای همهی زمانها، مثبت بودن آن است که به شکل ضرائب فرکانسی دنبالههای وابسته میباشد. به جای فرستادن دادهها به صورت مستقیم روی ...
this paper investigates the multi-band ofdm (mb-ofdm) based physical (phy) layer proposal for ieee 802.15.3a working group on short-range high data-rate ultra-wide-band (uwb) communications. an overview of the mb-ofdm phy layer architecture with its various parameters is presented and the optimal choice of critical parameters is discussed. next, we derive the theoretical un-coded bit error rate...
Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPT-OFDM) have been introduced to wired and wireless communication fields as efficient Multicarrier Modulation (MCM) techniques. The wavelets have interesting features such as flexibility, compatibility and localization in both time and frequency domains with no need to use ...
Tone Reservation (TR) is one of the well-known methods for PAPR reduction of Orthogonal Frequency Division Multiplexing (OFDM) systems. In this method some sub-carriers are reserved for PAPR reduction and the symbols in these sub-carriers are selected such that the PAPR of the OFDM frame is minimized. In this paper, the iterative algorithm introduced earlier for TR method in single antenna OFDM...
This paper presents an empirical mode decomposition (EMD) based adaptive filter (AF) for channel estimation in OFDM system. In this method, length of channel impulse response (CIR) is first approximated using Akaike information criterion (AIC). Then, CIR is estimated using adaptive filter with EMD decomposed IMF of the received OFDM symbol. The correlation and kurtosis measures are used to sel...
Orthogonal frequency division multiplexing (OFDM) has become a promising method for many wireless communication applications. However, one main drawback of OFDM systems is the high peak-to-average power ratio (PAPR). Selected mapping (SLM) is a well-known technique to decrease the problem of high PAPR in OFDM systems. In this method, transmitter is obliged to send some bits named side informati...
The high Peak to Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) and MIMO-OFDM systems reduces the system efficiency. In this paper, an extension of Tone Reservation (TR) method is introduced for PAPR reduction in Space Frequency Block Coded OFDM (SFBC-OFDM) systems. The proposed algorithm is based on a time domain kernel which is added to the signal of the anten...
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