نتایج جستجو برای: سیستم ofdm

تعداد نتایج: 84420  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده مهندسی برق و کامپیوتر 1386

مدولاسیون ofdm امروزه به عنوان روشی مقبول در ارسال بی سیم اطلاعات با نرخ بالا مطرح است. با تقسیم یک کانال محوشدگی باند پهن به کانالهای باریک و تخت، ofdm با استفاده از همسانسازی ساده یک شیره قادر به مقابله با اثرات مخرب پدیده محوشدگی کانال است. یکی از موضوعاتی که در این تحقیق مورد بررسی قرار می گیرد تخمین کانال بی سیم با استفاده از الگوریتم کالمن است. الگوریتم کالمن برای تخمین فرآیندهایی که بر ...

2003
Himal A. Suraweera Jean Armstrong

In this paper we address the issue of OFDM and PCC-OFDM systems impaired by phase noise (PN). PCC-OFDM is a variation of OFDM in which data is mapped onto adjacent subcarrier pairs. As a result intercarrier interference (ICI) in adjacent subcarriers is cancelled. Phase noise in OFDM causes both ICI and common phase error (CPE). PCC-OFDM reduces the ICI component, but the CPE is unchanged. Theor...

Journal: :EURASIP J. Adv. Sig. Proc. 2004
Neng Wang Steven D. Blostein

We present a novel bandwidth (BW) efficient orthogonal frequency division multiplexing (OFDM) scheme with adaptive zeropadding (AZP-OFDM) for wireless transmission. Redundancy issues in OFDM based on cyclic prefix (CP), zero-padding (ZP), as well as no guard interval (NGI) systems are analyzed. A novel system design criterion based on the channel matrix condition is studied and applied to the d...

2011
Ranjan Bala Jain

It is necessary to consider fast varying channel for Orthogonal Frequency Division Multiplexing (OFDM) system when OFDM symbols are transmitted over a frequency selective time varying fading channel. The time variations of channel during one OFDM symbol destroy the orthogonality of different subcarriers and result Inter Carrier Interference (ICI), which results in degradation of system performa...

2006
X. Yuan T. Abhayapala

In Cyclix Prefix OFDM (CP) systems, synchronization to the maximal multipath signal generally causes no problem, however, inter carrier interference (ICI) will be introduced in Zero-padding OFDM (ZP-OFDM) systems, e.g, multiband OFDM UWB (MB-OFDM) systems. In this paper, based on the overlap-and-add (ZP-OFDM-OLA) method typically applied in MB-OFDM, we analyze the cause of the ICI and the perfo...

2000
Bertrand Muquet Marc de Courville Georgios B. Giannakis Z. Wang Pierre Duhamel

The widespread application of OFDM for local area mobile wireless broadband systems is strongly motivated by the simple equalization it a ords. OFDM's bottleneck of channel-dependent performance was only recently addressed by replacing the cyclic pre x (CP) with trailing zeros (TZ). Such zero-padded OFDM transmissions enable FIR channel-irrespective symbol recovery which results in signi cant B...

Journal: :IEEE Communications Letters 2021

Unique Word Orthogonal Frequency Division multiplexing (UW-OFDM) is a variant of the multicarrier technique that has shown better bit error performance compared to cyclic prefixed (CP-)OFDM. Like other techniques, UW-OFDM suffers from high peak-to-average-power ratio (PAPR) problem, which an obstacle ahead practical implementation UW-OFDM. In this letter, generator matrix, inherent UW-OFDM, not...

2014
T. V. Ramesh A. Jaya Prakash

orthogonal frequency division multiplexing (OFDM) is the most popular modulation technique in modern wireless communication systems. Even though there are many advantages of OFDM, it has two main drawbacks: High peak-to-average power ratio (PAPR) and frequency offset. In this paper the issue of PAPR in OFDM is discussed. Due to the large number of subcarriers used, OFDM systems have a large dyn...

2012
Sanjeev Kumar

This paper discuss the Low Complexity Post-Coded MIMO OFDM (PC-MIMO OFDM) Systems: Design and performance analysis. The signal is propagating from the transmitter to receiver along number of different paths, referred as multipath in wireless environment. Path loss, macroscopic fading and microscopic fading are propagating signal power drops. Orthogonal Frequency Division Multiplexing (OFDM) pro...

2013
A. SenthilKumar

Orthogonal frequency-division multiplexing (OFDM) is a well-known technique for transmission of high rate data over broadband frequency-selective channels that mitigates intersymbol interference (ISI) caused by the delay spread of wireless channels. Space Frequency Block Coded technique (SFBC) is a spatial diversity technique used to achieve full transmission diversity with higher capacity. The...

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