Thomasphd candidate university of texas at dallas 2. Ofdm technique and its simulation using matlab youtube. Orthogonal frequency division multiplexing multicarrier modulation scheme fftbased. Ofdm receiver part consists of fft, bpsk demodulator and viterbi decoder. Implementing ofdm modulation for wireless communications next generation wireless systems fe ature highly dynamic configurations, where the cyclic prefix length changes according to the transmission mode, frame structure, and higher level protocol.
It is being used because of its peak data rate and spectral efficiency. Ofdm introduction ee225c introduction to ofdm lbasic idea. Capacity limit for fasterthannyquist nonorthogonal frequency. 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. Lte uses ofdma orthogonal frequency division multiple access technology for radio transmission and reception in downlink.
Concepts of orthogonal frequency division multiplexing. Ofdm basic transmitter receiver matlab code ofdm matlab. In case of dispute, the reference shall be the printing on etsi printers of the pdf version kept on a specific network drive within etsi secretariat. Lte is based on orthogonal frequency division multiplexing ofdm with cyclic prefix cp in the downlink, and on singlecarrier frequency division multiple access scfdma with cyclic prefix in the uplink. Orthogonality gives the carriers a valid reason to be closely spaced, even overlapped. Lte uses orthogonal frequency division multiplexing ofdm as its radio technology in downlink. Within cp ofdm the last part of data of ofdm frame is appended at the beginning of the ofdm frame and length of cyclic prefix is chosen to be greater than channel delay spread. As a result, devices with designs optimized for cp ofdm.
Orthogonal frequency division multiplexing is a multicarrier digital communication scheme to solve both issues. I am currently working on a dissertation on lte, namely the creation of a simulation model of ofdm and ocdm on matlab. High papr requires expensive and inefficient power amplifiers with high requirements on linearity. Number of samples in each symbol and cp varies with sampling rate. The faculty of engineering and science department of electronic systems. Synchronization for general ofdm systems has been investigated. Expected in the 2008 time frame, lte is a 3gpp standard that provides for an uplink speed of up to 50 megabits per second mbps and a downlink speed of up to 100 mbps.
The specific version of ofdm used in 5g nr downlink is cyclic prefix ofdm, cp ofdm and it is the same waveform lte has adopted for the downlink signal. 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. Within the basic lte ofdm signal format a variety of modulation formats are used including psk and qam. It brought a new foundational air interface design based on ofdm 5 waveforms and multiple access with ofdma 6 downlink and scfdma 7 uplink. Lte uses a precoded version of ofdm called single carrier frequency division multiple access sc. This is to compensate for a drawback with normal ofdm, which has a very high peak to average power ratio papr. The ofdm matlab code for the above block schematic is provided below for download. For instance, the cyclic prefix configuration for 3gpp lte chan ges within each sl ot, as shown in. Higher order modulation is used to achieve the higher data rates. Pdf probability density function psk phase shift keying qam quadrature amplitude modulation qpp quadratic permutation polynomial. 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.
Basics of osi and tcpip layers pdf file function of router ofdm versus ofdma main difference remote radio head or rrh 11a physical layer inside. Introduction the evolution of internet and the growing demand of high data rate users have given dynamic spectrum access networks a widespread attention in the recent years. Lte or long term evolution is the brand name given to the efforts of 3gpp 4th. Ofdm baseband receiver design for wireless communications tzidar chiueh and peiyun tsai. Different to the common fractional fourier transformbased nofdm frftnofdm signal, frctbased nofdm. Ip ofdm lte tx description ip ofdm lte tx is used to accelerate the hardware implementation of the 3gpp lte physical layer on virtex5 and virtex6 fpgas. Ten paired and four unpaired spectrum bands have so far been. Concepts of orthogonal frequency division multiplexing ofdm and 802. Orthogonal frequency division multiplexing ofdm is a multicarrier broadband modulation technique for transmitting large amounts of digital data.
Ofdma, orthogonal frequency division multiple access in the downlink and scfdma, single channel orthogonal frequency division multiple access in the uplink. Multiplexing method of sharing a bandwidth with other independent data channels. It supports both fdd and tdd duplex modes for transmission on. Fbmc, ofdm, multicarrier, prototype filter, 5g, lte 1. Since these new waveforms are different from the cp ofdm waveform used in lte lte advanced, papr and spectrum shape are also different. Lte also supports both fdd frequency division duplex and tdd. Papr reduction techniques in ofdm signal file exchange. Overview of the 3gpp long term evolution physical layer. Dynamic range test case for a 5 mhz lte signal the following example describes a dynamic range test case for a 5 mhz lte signal. Lte history and context lte s study phase began in late 2004. In ultra wideband technology uwb multiband concept is used which is the division of the total band. Carrier frequency synchronization in the downlink of 3gpp lte. Wcdma and ltewcdma and lte synchronization aspectssynchronization aspects the 6th international telecom sync forum, itsf munich, november 2008.
Lte technology has been covered most of the end user demands in terms of better spectral efficiency and maximum throughput. In a faucet all water comes in one big stream and cannot be subdivided. Scribd is the worlds largest social reading and publishing site. Robust again narrowband interference ldisadvantages. Trafficaware user association in heterogeneous lte.
Ofdm is a combination of modulation and multiplexing. The mathematical expression shows that ftn nofdm signal has the. Lte uses orthogonal frequency division multiplexing ofdm as its radio access technology, together with advanced antenna technologies. Orthogonal frequency division multiplexing ofdm modulation a mapping of the information on changes in the carrier phase, frequency or amplitude or combination. Capacity limit for fasterthannyquist nonorthogonal.
Mimo ofdm for lte, wifi and wimax coherent versus noncoherent and cooperative turbotransceivers prof. These methods offer to improve cp ofdm using subcarrier filtering but each filtering method is different. Ofdm forms the basic signal format used within 4g lte. 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. Ofdm, orthogonal frequency division multiplex is the basic format used and this is modified to provide the multiple access scheme. Long term evolution lte 1 has been standardized as the successor of the universal mobile telecommunication system.
Efficient fastconvolution based waveform processing for. Ming jiang currently with new postcom equipment co. Its important to have a fundamental understanding of orthogonal frequency division multiplexing ofdm because this technology is a basic building block for many of the current modulation schemes including. According to 1 the desired lte signal will be raised to 70. It is the latest wireless communication standard, which is developed by third generation partnership project 3gpp. Lte is designed to meet carrier needs for highspeed data and media transport as well as highcapacity voice support well into the next decade. As an analogy, a fdm channel is like water flow out of a faucet, in contrast the ofdm signal is like a shower. It combines a large number of low data rate carriers to construct a composite high data rate communication system. Ofdm presentation contentsspeaker biographyintroduction to ofdmofdm system modelofdm mathematical modelcharacteristics of ofdm advantages disadvantagesusage of ofdm 3. 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. Long term evolution lte is known as the 4th generation cellular technology. The mathematical expression shows that ftn nofdm signal has the potential to achieve a higher capacity limit compared to nyquist signal.
Ofdm transmitter in this example consists of fec encoder, bpsk modulator and 256 point ifft. Impact of channel models in mimo ofdm for lte aalborg university may 2012. This core implements that frontend vectorsignal generator for ofdm transmit functions for cyclic prefix generation, signal generation, and windowing used in lte applications. Using a large number of parallel narrowband subcarriers instead of a single wideband carrier to transport information ladvantages. Lte long term evolution is the latest technology in wireless communication.
In the dsa networks, multiple nodes contend to employ a shared frequency. In this paper, we propose a fasterthannyquist ftn nonorthogonal frequencydivision multiplexing nofdm scheme for visible. Choose a web site to get translated content where available and see local events and offers. Enhancement of the utra optimisation of the utran architecture to ensure the continued competitiveness of the 3gpp technologies for the future lte was the first and only technology recognized by the next generation mobile network alliance to meet its broad requirements target deployment in 2010. Long term evolution lte is the result of the standardization work done by 3gpp to achieve a high speed.
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