Finally, the main differences between lte tdd and fdd modes are examined and hspa evolution in 3gpp releases 7 and 8 is described. Pdf performance analysis of ofdma in lte researchgate. The operator license can be shared highly efficiently between lte and gsm portions with the rf sharing solution. The detailed specification of lte is given in table 1. Performance analysis of scfdma and ofdma in lte frame structure. Introduction to orthogonal frequency division multiplexing ofdm cyclic prefix cp and circul. Ofdma, orthogonal frequency division multiple access in the downlink and scfdma, single channel orthogonal frequency division multiple access in the uplink. The scalable or sofdma versions encompass the 128 fft, 512 fft, and 1024 fft as promoted by intel and others. The ofdma 2048 fft version was conceived as a fixed fft and is supported in both 802. To minimize papr, lte has adapted sc fdma single carrier frequency division multiple access in the uplink. In ofdma, both time and frequency are distributed among users.
Typical values for each system bw is as follows system bw number of rbs n ifft binsifft 1. 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. Request pdf orthogonal frequency division multiple access ofdma summaryofdm is the modulation of choice for the lte downlink, the key advantages being the low complexity of the receiver. Apr 01, 2009 lte for umts is one of the first books to provide a comprehensive guide to the standards and technologies of lte. Figure 2 illustrates the concepts of ofdma and scfdma.
Within the basic lte ofdm signal format a variety of modulation formats are used including psk and qam. Aug 22, 2014 lte for umts ofdma and scfdma based radio access lte for umts ofdma and scfdma based radio access pdf, epub ebook d0wnl0ad from the editors of the highly successful wcdma for umts, this new book gives a complete and uptodate overview of long term evolution lte in a systematic and clear manner. Orthogonal frequencydivision multiple access ofdma is a multiuser version of the popular orthogonal frequencydivision multiplexing ofdm digital modulation scheme. This chapter presents an overview of the theoretical background of ofdm together with its parameterization for lte. Lte is a candidate technology for public safety broadband wireless service, perhaps in a modified core network form a discussion of the acronym ridden lte standard is timely given the united states government priority on expanding availability of broadband services to the entire population a number of wireless technologies will compete. Introduction in order to transition from todays 3rd generation 3g communications systems to meet the needs of 4th. Implementation of ofdma and multiple antenna techniques in. One company in the forefront of this type of ofdma technology is runcom.
Both ofdm and ofdma are used in many modern wireless systems including acmimo radio, 802. Although it is mandatory for the mobiles to have capability to be able to receive all 2048 subcarriers, not all need to be transmitted by the base station which only needs to be able to support the transmission. Ofdma as 3gpp longterm evolution uplink friday december 4, 2009 ee359 project nima soltani 1. Ofdma physical layer basics mobile wimax physical layer. In addition to ofdma technology, different mimo transmission methods are used to achieve data rate compliance with the lte standards. Ofdm forms the basic signal format used within 4g lte. Radio imt advanced based on lte release 10 and beyond. Umts long term evolution lte technology introduction.
Lte is designed to meet carrier needs for highspeed data and media transport as well as highcapacity voice support well into the next decade. The umts long term evolution lte is an emerging technology in the evolution of 3g cellular services. Lte for umts is one of the first books to provide a comprehensive guide to the standards and technologies of lte. Orthogonal frequency division multiple access as the radio access technology due to its simple implementation in receiver, high performance and high spectral efficiency. Each of these subcarriers is independently modulated by a low rate data. Robust again narrowband interference ldisadvantages. A variant is used in lte ofdma only for the downlink does this sound familiar. Pdf the lte employs ofdma for downlink data transmission because orthogonal frequency division multiple access ofdma scheme. Ofdm is the modulation of choice for the lte downlink, the key advantages being the low complexity of the receiver, high spectral efficiency and avoidance of inter. Orthogonal frequencydivision multiple access ofdma is a feature of wifi 6 802. Later, orthogonal frequencydivision multiple access ofdma was adopted by the wimax forum for mobile wimax systems and more recently by the 3gpp for the downlink of long term evolution lte. This page on the ofdm vs ofdma describes difference between ofdm and ofdma modulation schemes.
Ofdma will be the predominant technology for the air interface of broadband mobile wireless systems for the next decades. Lte ofdma in the downlink the ofdm signal used in lte comprises a maximum of 2048 different subcarriers having a spacing of 15 khz. This is to compensate for a drawback with normal ofdm, which has a very high peak to average power ratio papr. 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. In ofdmtdma, timeslots are attributed to each users and the whole ofdm symbol is dedicated to one user. For practicality, sc ofdma is implemented in lte using a discrete fourier transform spread ofdm. Overview of the 3gpp long term evolution physical layer nxp. High papr requires expensive and inefficient power amplifiers with high requirements on linearity. This article provides a comprehensive overview of the implementation of orthogonal frequency division multiple access along with multiple antenna schemes in the two dominant 4g standards, wimax and. Nokia siemens networks lte 1800 mhz introducing lte with.
As an ofdma technology lte assumes small nominal guard band 10 %, excluding 1. Orthogonal frequency division multiple access ofdma scheme is the transmission scheme used for lte fdd and lte tdd operational modes in the downlink. Lte physical layer fundamentals and test requirements. Although lte uses a different form of radio interface using ofdma sc. Although there are major step changes between lte and its 3g predecessors, it is nevertheless looked upon as an evolution of the umts3gpp 3g standards as shown in the table 1. Oct 05, 2016 ofdmasc fdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. I am looking for a clear and precise explanation of how an ofdma modulator in downlink lte operates. In recent years, ofdma based networks based on ieee 802. Long term evolution is a new advancement in the era of cellular technology emerged in recent decade that can accommodate the features of quite efficient radio access with high peak data rates as well as high capacity for voice links.
Furthermore, mimo antenna schemes form an essential part of lte. 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. Ofdma orthogonal frequency division multiple access in downlink and scfdma single carrier frequency division multiple access in uplink. The prime cause of this high speed of lte systems is the advancement in physical layer. Performing an idft converts the frequencyshifted signal to the time domain and inserting the cp provides the fundamental robustness of ofdma against multipath. Lte long term evolution is one of such area research have been carried on to fulfill the above. The present document is part 50 of a multipart deliverable. This article describes ofdma basics, ofdma frame structure, ofdma symbol, ofdma physical layer as per ieee 802. Difference between ofdm and ofdma compare the difference. It also explains ofdma tdd frame which consists of pusc, fusc and amc zones in the downlink and puscamc zones in the uplink.
Covers all the key aspects of lte in a systematic manner presents full description of 3gpp release 8 lte examines the expected performance of lte written by experts actively involved in the 3gpp. Further updates and modification were later made in release 9 in 2009 and lte advanced introduced in release 10 in 2011. Ofdm, orthogonal frequency division multiplex is the basic format used and this is modified to provide the multiple access scheme. This allows simultaneous lowdatarate transmission from several users. Lte for umts ofdma and scfdma based radio access lte for umts ofdma and scfdma based radio access pdf, epub ebook d0wnl0ad from the editors of the highly successful wcdma for umts, this new book gives a complete and uptodate overview of long term evolution lte in a systematic and clear manner. The relationship between scfdma and ofdma is illustrated in figure 2. Mimo and single carrier frequency division multiple.
Then well have to allocate the information to send it. Lte an optimized ofdma solution for wider bandwidth spectrum. Ofdma physical layer basics mobile wimax physical layer as. Introduction long term evolution lte enhances the susceptibility and. The resource blocks have a total size of 180khz in the frequency domain and 0. 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. Performance evaluation of lte physical layer using scfdma. Lte uses a precoded version of ofdm called single carrier frequency division multiple access sc. You can use this syntax for lte, singletone nbiot, and multitone nbiot configurations. Lte, the ofdma is used as downlink and scfdma as uplink modulation. Lte, ofdma, scfdma, dft, idft, error rate, bandwidth.
The orthogonal frequency division multiple access ofdma based systems are being adopted for use in different flavors of bcw systems 1. Long term evolution lte, frequency division duplex fdd, time division duplex tdd, single carrier frequency division multiple access scfdma, orthogonal frequency division multiple access ofdma, additive white gaussian noise awgn 1. The concept was first introduced in the release 8 document series of 3gpp in the 4th quarter of 2008. In an ofdm system, the total available spectrum is divided into multiple carriers. Burr, lingyang song, yan zhang and thomas michael bohnert citation. Orthogonal frequencydivision multiple access wikipedia. Higher order modulation is used to achieve the higher. Long term evolution lte is a wireless communication standard developed by the 3rd generation partnership project 3gpp. In the uncoordinated case it is 3gpp recommended practice that the center. Jul 27, 2016 ofdm for lte tdd subframe structure type 1 first ofdm symbol within a slot is little bit longer than other ofdm symbols. Resource optimisation for 3rd generation partnership project. This page covers excel sheets 11n data rate table, fixed wimax bandwidth table, mobile wimax bw with fs, 16e data rate calculator, evm conversions, pdf ppt files ofdm versus ofdma,osi,rrh,11a physical layer,router, beamforming and projects in matlab and simulink. Many methods employed in lte are relatively new in cellular applications. Orthogonal frequency division multiple access ofdma.
Apr 07, 2017 one of the key features driving this connectivity improvement is orthogonal frequencydivision multiple access ofdma. Ofdma introduction and overview for aerospace and defense. The next generation 3gpp longterm evolution lte mobile system will use orthogonal frequency division multiplexing access ofdma as the key technology to improve the spectrum efficiency and. Inphase addition of subcarriers creates peaks in the ofdm signal. The tabular comparison between ofdm and ofdma are also outlined. Lte a welldesigned mobile ofdma ip solution qualcomm. This multiplexing digital modulation scheme introduces newfound permeability into highly dense wifi traffic scenarios. The other file return a 60x15 matrix 60 subchannels x 15 ofdma symbols and it is said on that matrix which user has to transmit in each slot. Using a large number of parallel narrowband subcarriers instead of a single wideband carrier to transport information ladvantages.
Frequency selective rayleigh fading channel is considered as a model for real life scenario of the lte evaluation, operating in 5 mhz downlink bandwidth of ofdma parameters as proposed in the standard. To complete scfdma signal generation, the process follows the same steps as for ofdma. I know it is a very basic file but it might help someone if he wants to improve that file. I have many books that explain it but each has its own way and do not answer my questions completely. Ofdma signal mapping process file exchange matlab central. The voice solution and voice capacity in lte are also illustrated. Multiple access is achieved in ofdma by assigning subsets of subcarriers to individual users. Ofdma architectures, protocols, and applications authors. Overview of the 3gpp long term evolution physical layer. Ofdma follows a set of rules created for the transmission of data between more than one terminal any device at the end of a transmission channel, such as a computer or phone over a transmission medium such as a wireless network. Ofdm support multiple users multiple access via tdma basis only, while ofdma support either on tdma or fdma basis or both at the same time. 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. Orthogonal frequency division multipleaccess ofdma is used for the downlink, and scfdma is used for the uplink as multipleaccess schemes in the lte system.
Rf chipset verification for lte with smu200a and fsq ver1. Lte performs in the frequency ranges from 1,4 mhz to 20 mhz and supports mimo antennas which allow to increase the datarate and coverage. 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 noise. In ofdm systems, only a single user can transmit on all of the subcarriers at any given time. The lte air interface is well scalable in terms of bandwidth. We will go through mobile wimax ofdma physical layer which. Jul 31, 2014 pointtomultipoint fixed and mobile systems use ofdma and most emerging systems are using ofdma such as mobile wimax and lte. Jul 05, 2016 as it was mentioned earlier, lte uses ofdma orthogonal frequency division multiple access in the radio interface, which works with a large number of orthogonal subcarriers very close between them. Frequency division multiple access ofdma in downlink dl and single carrier frequency division multiple access scfdma for uplink ul, as shown in figure 3. One of the key features driving this connectivity improvement is orthogonal frequencydivision multiple access ofdma. Design and analysis of ofdma and scfdma for lte uplink.