In fact, ofdm was the key technology of other standards like dbvt. Ofdm is used by epoc, a wire coaxial cable technology, see ieee 802. Lte is designed to meet carrier needs for highspeed data and media transport as well as highcapacity voice support well into the next decade. Ofdma orthogonal frequency division multiple access. Oct 05, 2016 ofdmasc fdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. Ofdmasc fdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. Overview of the 3gpp long term evolution physical layer 1 1 introduction the 3gpp long term evolution lte represents a major advance in cellular technology.
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 associated access schemes, ofdma orthogonal frequency division multiple access and scfdma single carrier frequency division multiple access. With ofdm, a wideband carrier is transmitted as narrowband subcarriers. An introduction to orthogonal frequency division multiplex ofdm. 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. An example is used to compare and contrast single carrier vs. First part of the preamble is exactly the same with the second part use crosscorrelation to detect the preamble. Keysight technologies ofdma introduction and overview for. In the present scenario, high data rate are provided by wlan, wimax and lte lteadvanced ltea. Wireless tutorial wifi, 4g, 3g, white spaces and beyond. Orthogonal frequency division multiplex ofdm, dmt download.
One of the key elements of lte is the use of ofdm orthogonal frequency division multiplex as the. Ofdm splits data into small subcarriers, also known as data streams, on neighboring frequencies, over a single channel. 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 ofdm s associated access schemes, ofdma orthogonal frequency division multiple access and scfdma single carrier frequency division multiple access. The evolved version of long term evolution is lteadvanced which is being developed by the. Techniques for peaktoaverage power ratio reduction, time and frequency synchronization, and channel estimation will be discussed. Lte ofdm technology to overcome the effect of multi path fading problem available in umts, lte uses orthogonal frequency division multiplexing ofdm. Lte qos lte architecture supports hard qos, with endtoend quality of service and guaranteed bit rate gbr for radio bearers. The magnitude of each carrier is 1, but it could be scaled to any value. Tutorial 22 orthogonal frequency division multiplex ofdm, dmt posted on december 17, 2012 by charan l. Lte or 4g provides a series of improvements over umts universal mobile telecommunications system and it is introduced from 3gpp 3rd generation partnership project. The toolbox accelerates lte algorithm and physical layer phy development, supports golden reference verification and conformance testing, and enables test waveform. This report investigates the performance of ofdma and various mimo configurations of lte. Jun 17, 2019 ofdm is used by epoc, a wire coaxial cable technology, see ieee 802. Lte uses ofdm as the basic signal format ofdma in the downlink and sc fdma in the uplink with various modulation.
Lte history and context lte s study phase began in late 2004. The main focus is on the singlecarrier frequency division multiple access scfdma scheme which has been selected as the multipleaccess scheme of the lte uplink. The demand for increased channel capacity in wireless and mobile communication has been rapidly increasing due to multi fold increase in demands of mobile data and multimedia services. Ofdm orthogonal frequency division multiplexing is the radio science behind huge bandwidth capabilities we see in lte. Ofdm transmitter in this example consists of fec encoder, bpsk modulator and 256 point ifft. In telecommunications, orthogonal frequencydivision multiplexing ofdm is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. Ofdm ofdma in 4g lte part 1 how can we stream a full hd movies seamlessly. Orthogonal frequency division multiplexing ofdm is the basis of lte. It looks like lte ofdm formular is much more complicated. The high peaktoaverage power ratio papr associated with ofdm led 3gpp to look for a different modulation scheme for the lte uplink. Overview of the 3gpp long term evolution physical layer nxp. Multicarrier transmission over mobile radio channels.
Orthogonal frequencydivision multiplexing wikipedia. 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 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. Lte toolbox provides standardcompliant functions and apps for the design, simulation, and verification of lte, lteadvanced, and lteadvanced pro communications systems. Orthogonal frequency division multiplexing ofdm has become attractive for. Because the lte mac is fully scheduled, qos is a natural fit. I put the ltenb ofdm waveform generation formula and lte formula toghether for comparision. Ofdm has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, dsl internet access, wireless networks, power line networks, and 4g. The lectures also cover channel mapping and ue categories. The best way to learn about ofdm basic facts is to look at a good ofdm video tutorial.
Ofdm receiver part consists of fft, bpsk demodulator and viterbi decoder. Chang in 1966 at bell labs but has been widely used for only the last 15 years. Tutorial 22 orthogonal frequency division multiplex. Jul 05, 2016 in fact, ofdm was the key technology of other standards like dbvt. In multiuser channel spread mimo ofdm provides more capacity than the other schemes. This is followed by lectures that cover lte frequency bands, ofdm, ofdma, scfdma and lte signaling. The bandwidth is 258 mhz 1218 mhz splitted in 5 channels. As in normal lte, ltenb downlink is using ofdm waveform as well. To overcome the effect of multi path fading problem available in umts, lte uses orthogonal frequency division multiplexing ofdm for the downlink that is, from the base station to the terminal to transmit the data over many narrow band careers of 180 khz each instead of spreading one signal over the complete 5mhz career bandwidth ie. Audience this tutorial has been designed for audiences with a need to understand the. Ofdm, orthogonal frequency division multiplexing has gained a significant presence in the wireless market place. It allows sending more data than through single carrier modulation techniques, and at a higher rate.
Lte uses orthogonal frequency division multiplexing ofdm as its radio access technology, together with advanced antenna technologies. In this tutorial, we present the basic principles of ofdm and discuss the problems, and some of the potential solutions, in implementing an ofdm system. Wireless tutorial wifi, 3g, 4g, white spaces and beyond. The ofdm matlab code for the above block schematic is provided below for download. Ofdma, orthogonal frequency division multiple access in the downlink and scfdma, single channel orthogonal frequency division multiple access in the uplink. Many methods employed in lte are relatively new in cellular applications. For this example, there are 4 carriers, the ifft bin size is 64, and there is only 1 bit per symbol.
Overview of the 3gpp long term evolution physical layer. 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. The technical specifications approved by 3gpp for the lte project include the use of orthogonal frequency division multiplexing ofdm and advanced antenna technologies such as mimo multiple input multiple output. The term ofdm for wireless, the terms dmt and ofdm for wire ofdm for large bandwidth 250 mhz, dmt otherwise. Ofdm, orthogonal frequency division multiplex is the basic format used and this is modified to provide the multiple access scheme. Systems beyond imt2000 imtadvanced is set to introduce evolutionary path beyond 3g. Lte tutorial for beginners learn lte online training.
Mimo technologies in 3gpp lte and lteadvanced article pdf available in eurasip journal on wireless communications and networking 20091 january. Prerequisites basic understanding on any of the network technologies like gprs, gsm, core network, radio interfaces etc is expected before diving into the tutorial. Mimo and single carrier frequency division multiple. Ofdm, 10 db mccdma, 20 db 30 db mccdma, 10 db ofdm, 20 db ofdm, 30 db localmean ber for bpsk, versus antenna speed. Ofdm introduction ee225c introduction to ofdm lbasic idea. The symbol time and bandwidth of ofdm subcarriers is. In addition to ofdm, lte implements multipleantenna techniques such as mimo multiple input. An introduction to orthogonal frequency division multiplex. Ofdm technology was used for the signal format for lte because it enabled high data bandwidths to be transmitted efficiently while still providing a high degree of resilience to reflections and interference. Scfdma was chosen since it combines the low papr techniques of singlecarrier transmission systems, such as gsm and cdma, with the multipath resistance and flexible frequency allocation of ofdma. Orthogonal frequencydivision multiplexing for beginners.
Orthogonal frequency division multiplexing is a multicarrier digital communication scheme to solve both issues. Figures 25 from 3 present the results of that paper. Introduction to orthogonal frequency division multiplexing ofdm cyclic prefix cp and circul. The overall goal was to select technology that would keep 3gpps universal mobile telecommunications system umts at the forefront of mobile wireless well into the next decade. Ofdm basic transmitter receiver matlab code ofdm matlab. Myung 2 beyond 3g international mobile telecommunications imt2000 introduced global standard for 3g.
Nov 26, 2007 globecom 2007 tutorial mujtaba, winters 2 outline ofdm basics mimo basics 3gpp lte standard ieee 802. In multiuser channel spread mimoofdm provides more capacity than the other schemes. It provides enough depth into the concepts of lte technology which can lead to higher level of expertise. Ofdm is a particular form of multicarrier transmission and is suited for frequency selective channels and high data. Introduction to ofdm orthogonal frequency division. It specifies downlink peak speeds of 326mbps and uplink peak speeds of 86mbps, both in a 20 mhz bandwidth. Ofdm modulation is applied in the frequency domain. Scfdma and lte uplink physical layer design burcu hanta 02. The combination of high data capacity, high spectral efficiency, and its resilience to interference as a result of multipath effects means that it is ideal for the high data applications that have become a major factor in todays. Comparison between mccdma and uncoded ofdm for fc 4 ghz frame durationts 896s fft size. Ofdm has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, dsl internet. In this section, we cover the basics of ofdm and provide an overview of the lte physical layer. However, you will probably find the following article useful to learn some basic ofdm information.
The paper starts with a brief introduction to the ofdm. Error mmse haven been evaluated for different channel models in lte. May 20, 2015 ofdm orthogonal frequency division multiplexing is the radio science behind huge bandwidth capabilities we see in lte. Introduction to ofdm orthogonal frequency division multiplexing.
For practicality, scofdma is implemented in lte using a discrete fourier transform spread ofdm transmission. Examples of standards that use ofdm are lte, lte advanced, wimax, digital audio and video broadcast, wlan, and adsl. This seems reasonable since ofdm with long enough cyclic prefix is a powerful mean to mitigate multipath. Robust again narrowband interference ldisadvantages. December 2009 abstract the long term evolution lte physical layer design is covered as the main topic in this report.
Oct 29, 2012 the best way to learn about ofdm basic facts is to look at a good ofdm video tutorial. Lte uses ofdm as the basic signal format ofdma in the downlink and scfdma in the uplink with various modulation. Using a large number of parallel narrowband subcarriers instead of a single wideband carrier to transport information ladvantages. I put the lte nb ofdm waveform generation formula and lte formula toghether for comparision. You may think there is a big difference between the two, but actually not so much difference. It combines a large number of low data rate carriers to construct a composite high data rate communication system. Figure 2 and figure 3 give an example of modulated ofdm carriers for one symbol period, prior to ifft. Abstractthis tutorial paper addresses the physical layer security concerns and resiliency of orthogonal frequency division multiplexing ofdm communications. In particular, many wireless standards wimax, ieee802. As in normal lte, lte nb downlink is using ofdm waveform as well. 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 first cell phones. Ofdm and scfdma lectures ofdm and multicarrier modulation. Mimo technologies in 3gpp lte and lteadvanced article pdf available in eurasip journal on wireless communications and networking 20091 january 2009 with 1,356 reads how we measure reads.
The downlink physical layer of lte is based on ofdma. Ofdm forms the basic signal format used within 4g lte. Technology for high speed wireless transmission abstract. Orthogonality gives the carriers a valid reason to be closely spaced, even overlapped. Just as ethernet and the internet have different types of qos, for example, various levels of qos can be applied to lte traffic for different applications. 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, scfdma, along with. Mobile class targets 100 mbps with high mobility and nomadic local area class targets 1 gbpswith low. Ofdm is a special form of the frequencydivision multiplexing fdm multicarrier modulation technique.
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