Lte stands for long term evolution and it was started as a project in 2004 by telecommunication body known as the third generation partnership project 3gpp. The bandwidth is 258 mhz 1218 mhz splitted in 5 channels. Tutorial 22 orthogonal frequency division multiplex. One of the key elements of lte is the use of ofdm orthogonal frequency division multiplex as the. Implementing ofdm modulation for wireless communications next generation wireless systems fe ature highly dynamic configurations, where the cyclic prefix length changes according to the. Introduction to orthogonal frequency division multiplexing ofdm cyclic prefix cp and circul. Dftspread ofdm with frequency domain reference symbols alphan sahin, erdem bala, rui yang, robert l. Unlike ofdm which allocates all the subcarriers of the ofdm symbol to one user, ofdma allocates subset of subcarriers to different users. While the basic concepts of ofdm are used, it has naturally been tailored to meet. Overview of the 3gpp long term evolution physical layer. Ofdma orthogonal frequency division multiple access one of the key elements of lte is the use of ofdm orthogonal frequency division multiplex as the signal bearer, as well as ofdms. Lte evolved from an earlier 3gpp system known as the universal mobile telecommunication system umts, which in turn evolved from the global system for mobile communications gsm.
Orthogonal frequency division multiplexing 10 data serial to parallel ifft foundation to ofdm synthesis cyclic prefix cp insertion windowing filtering 0s 0s to rf simplified ofdm waveform. Ofdm splits data into small subcarriers, also known as data. Dftspread ofdm with frequency domain reference symbols. For practicality, scofdma is implemented in lte using a discrete fourier transform spread ofdm transmission. Concepts of orthogonal frequency division multiplexing ofdm and 802. The orthogonal frequency division modulation ofdm demodulator system object demodulates an ofdm input signal by using an fft operation that results in n parallel data streams. Ofdm ofdma in 4g lte part 1 how can we stream a full hd movies seamlessly. Orthogonal frequency division multiplex ofdm tutorial 1 intuitive guide to principles of communications orthogonal frequency division multiplexing ofdm modulation a mapping of the information on changes in the carrier phase, frequency or amplitude or combination. Ofdm ppt orthogonal frequency division multiplexing mimo.
Many methods employed in lte are relatively new in cellular applications. Peaktoaverage power ratio an overview sciencedirect. Mimo and single carrier frequency division multiple. Ofdm stands for orthogonal frequency division multiplexing.
Concepts of orthogonal frequency division multiplexing. This report investigates the performance of ofdma and various mimo configurations of lte. Designing of lteadvanced downlink transceiver on a. Ofdm ofdma 4g mimo u ghput i i wimax lte 3g ieee 802 c ity thro cdma w ff 2g umtshsxpa e less capa amps gsm wir.
Overview of the 3gpp long term evolution physical layer nxp. Mobile class targets 100 mbps with high mobility and nomadic local area class targets 1 gbpswith low. It combines a large number of low data rate carriers to construct a. It is variation of fdm technique in which orthogonal subcarriers are closely spaced to have efficient utilization of. Nov 26, 2007 globecom 2007 tutorial mujtaba, winters 2 outline ofdm basics mimo basics 3gpp lte standard ieee 802. Its important to have a fundamental understanding of orthogonal frequency division multiplexing ofdm. Ofdm introduction ee225c introduction to ofdm lbasic idea. It provides enough depth into the concepts of lte technology which can lead to higher level of expertise. Sae system architecture evolution is the corresponding evolution of the gprs3g packet core network evolution. Ofdm is a spectrally efficient version of multicarrier modulation, where the subcarriers are selected such that they are all orthogonal to one another over the symbol duration, thereby avoiding the need to have nonoverlapping subcarrier channels to eliminate intercarrier interference. Ofdm technology was used for the signal format for lte because it enabled high data. Lte physical layer which in itself is a very large and featurerich topic, particularly as there are different modes of operation fddtdd and different downlink and uplink access technologies ofdma. Lte ofdm technology to overcome the effect of multi path fading problem available in umts, lte uses orthogonal frequency division multiplexing ofdm. Lte fundamentals free download as powerpoint presentation.
Ofdma orthogonal frequency division multiple access. Abstractthis tutorial paper addresses the physical layer security concerns and resiliency of orthogonal frequency division multiplexing ofdm communications. The high peaktoaverage power ratio papr associated with ofdm led 3gpp to look for a different modulation scheme for the lte uplink. Multicarrier transmission over mobile radio channels. The peaktoaverage power ratio papr for a singlecarrier modulation signal depends on its constellation and the pulse shaping filter rolloff factor. Ofdm orthogonal frequency division multiplexing is the radio science behind huge bandwidth capabilities we see in lte. Ofdm introduction ee225c introduction to ofdm lbasic idea using a large number of parallel narrowband subcarriers instead of a single wideband carrier to transport information ladvantages very easy and efficient in dealing with multipath robust again narrowband interference ldisadvantages sensitive to frequency offset and phase. Myung 2 beyond 3g international mobile telecommunications imt2000 introduced global standard for 3g. The evolved version of long term evolution is lteadvanced which is being developed by the. Tutorial 22 orthogonal frequency division multiplex ofdm, dmt posted on december 17, 2012 by charan l.
In fact, ofdm was the key technology of other standards like dbvt. Two competing factors in determining the right ofdm symbol time. With ofdm, a wideband carrier is transmitted as narrowband subcarriers. Higher spectral utilization makes ofdm a suitable candidate for future data transmission schemes like lte, power line communications, wimax and wran. Also, the use of multiple antennas to enhance spectral efficiency and reliability is. Orthogonal frequency division multiplex ofdm tutorial 1 intuitive guide to principles of communications orthogonal frequency division multiplexing ofdm. Systems beyond imt2000 imtadvanced is set to introduce evolutionary path beyond 3g. Orthogonal frequency division multiplexing ofdm is the basis of lte.
Introduction to ofdm orthogonal frequency division. Lte tutorial for beginners learn lte online training. Orthogonal frequency division multiplexing is a multicarrier digital communication scheme to solve both issues. Lte uses orthogonal frequency division multiplexing ofdm as its radio. Ofdm is used by epoc, a wire coaxial cable technology, see ieee 802. This is followed by lectures that cover lte frequency bands. Overview of the 3gpp long term evolution physical layer 1 1 introduction the 3gpp long term evolution lte represents a major advance in cellular. The term lte is typically used to represent both lte and sae.
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