Abstract long term evolution lte is a significant project of 3rd generation partnership project 3gpp, initially proposed on the toronto conference of 3gpp in 2004 and officially started as. 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. Jun, 2015 lte for umts ofdma and sc fdma based radio access april 2009. Mobile class targets 100 mbps with high mobility and nomadic local area class targets 1 gbpswith low. Ofdma will be the predominant technology for the air interface of broadband mobile wireless systems for the next decades. A survey of long term evolution washington university in. Single carrierfdma is a recently developed single carrier multiple access technique which has similar structure and performance to ofdma. Performance analysis of lte system using ofdma and sc. Difference between ofdm and ofdma compare the difference. The tabular comparison between ofdm and ofdma are also outlined. Orthogonal frequency division multiple access an overview. In ofdmtdma, timeslots are attributed to each users and the whole ofdm symbol is dedicated to one user.
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. In this tutorial article, we discuss the reasons for the popularity of ofdma and outline some of the important concepts which are used in ofdma as applied to bcw systems. When a data is transmitted over a channel in a bandwidth it is distorted due to multipath this can be avoided by breaking the available bandwidth into number. Qualcomm products referenced on this page are products of qualcomm technologies, inc. Oct 05, 2016 ofdma scfdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. Ltea welldesigned mobile ofdma ip solution 5 lte performance and key features. Ofdma as 3gpp longterm evolution uplink friday december 4, 2009 ee359 project nima soltani 1. Ofdma can be seen as an alternative to combining ofdm with timedivision multiple access. Although lte uses a different form of radio interface using ofdmasc. Now a days it is a right core technology in wireless communication. Materials that are as of a specific date, including but not limited to press releases, presentations, blog posts and webcasts, may have been superseded by subsequent events or disclosures. In recent years, ofdmabased networks based on ieee 802. Introduction ofdma is used in lte downlink process.
Implementation of ofdma and multiple antenna techniques. We show that for a cellular system employing orthogonal frequencydivision multipleaccess ofdma, the optimization of physicallayer transmission strategies can be done efficiently by. I am looking for a clear and precise explanation of how an ofdma modulator in downlink lte operates. It 1 aug 2018 1 nonorthogonal multiple access for 5g and beyond yuanwei liu, member, ieee, zhijin qin, member, ieee, maged elkashlan, member, ieee, zhiguo ding, senior member, ieee, arumugam nallanathan, fellow, ieee, and lajos hanzo, fellow, ieee, abstract driven by the rapid escalation of the wireless capacity requirementsimposed by advanced multimedia. We also investigate the performance of ofdma in lte physical layer by considering different. Introduction in order to transition from todays 3rd generation 3g communications systems to meet the needs of 4th.
Multiple access is achieved in ofdma by assigning subsets of subcarriers to individual users. 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. Systems beyond imt2000 imtadvanced is set to introduce evolutionary path beyond 3g. The peak data rate for lte forecast that it has a downlink speed of 100 mbps and uplink speed of 50 mbps.
Ofdmascfdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. In ofdma, both time and frequency are distributed among users. Design and analysis of ofdma and scfdma for lte uplink. Idma and orthogonal frequency division multiple access ofdma street converged to omanonorthogonal multiple access noma square of fig. Performance analysis of ofdma in lte alaa deshar farhood. Ofdma orthogonal frequency division multiple access. Lte was designed from the ground up for mobility and high capacity, as well as for efficient delivery of realtime applications such as voice through voip. Ofdma principles in lte, there are several ways to transmit over the frequency band and to share the resource between several devices.
Pdf performance analysis of ofdma in lte researchgate. 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. Scfdma can be viewed as a special ofdma system with the users signal preencoded by discrete fourier transform dft, hence also known as dftprecoded ofdma or dftspread ofdma. Implementation of ofdma and multiple antenna techniques in. This multiplexing digital modulation scheme introduces newfound permeability into highly dense wifi traffic scenarios. Orthogonal frequencydivision multiple access ofdma is a multiuser version of the popular. Orthogonal frequency division multiple access ofdma.
Materials that are as of a specific date, including but not limited to press releases, presentations, blog posts and webcasts, may have been superseded by subsequent events or. While ofdm is used in many broadband technologies such as wimax16d16e, wlan11a11n11ac. The umts long term evolution lte is an emerging technology in the evolution of 3g cellular services. In ofdm systems, only a single user can transmit on all of the subcarriers at any given time. In recent years, ofdma based networks based on ieee 802. The process of modulating data symbols and combining them is equivalent to an inverse fourier transform operation ifft.
A survey of ofdma and scfdma in lte system ankita bhatia1, pooja sharma2 1 m. Performance evaluation of lte physical layer using sc. Jan 23, 20 single carrierfdma is a recently developed single carrier multiple access technique which has similar structure and performance to ofdma. Robust again narrowband interference ldisadvantages. Jul 31, 2014 pointtomultipoint fixed and mobile systems use ofdma and most emerging systems are using ofdma such as mobile wimax and lte. This page on the ofdm vs ofdma describes difference between ofdm and ofdma modulation schemes. Both ofdm and ofdma are used in many modern wireless systems including acmimo radio, 802. With lte joining umb and wimax in choosing ofdm as the underlying modulation technology, it could be. Although lte uses a different form of radio interface using ofdma sc. Sofdma, in simple words, is the orthogonal frequency division multiple access ofdma mode employed in mobile wimax outlined in ieee 802. The physics of broadband wireless forces the designers of ofdma to make choices, and those choices have tradeoffs. I have many books that explain it but each has its own way and do not answer my questions completely. Sep 08, 2016 ofdm ofdma in 4g lte part 1 how can we stream a full hd movies seamlessly.
Ofdma, orthogonal frequency division multiple access in the downlink and scfdma, single channel orthogonal frequency division multiple access in the uplink. Here we give a comparison of the advantages and disadvantages of ofdma ofdm and cdma is often necessary to choose the correct system. 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. Jul 05, 2016 ofdma can be used as a dl access scheme, with the mac layer assigning subchannels to the dl data destined to the various ues.
In the dl, nbiot employs orthogonal frequency division multipleaccess ofdma, using the same numerologies as lte in terms of. Scalable orthogonal frequency division multiple access. They have also evolved further along spatial division multiple access sdma and multifunctional antenna array street these solutions have found their way into the 4g ofdma systems. When multiple transmit and receive antennas are employed at a basestation, the ofdma symbol processing functions have to be implemented for each antenna stream. Ofdma incorporates elements of time division multiple access tdma so. Ofdma can be used as a dl access scheme, with the mac layer assigning subchannels to the dl data destined to the various ues. Orthogonal frequencydivision multiple access wikipedia. Fundamentals of communications access technologies. Finally, to allow the device receiver to perform coherent combining, it is. Performance analysis of lte system using ofdma and scfdma.
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. Using a large number of parallel narrowband subcarriers instead of a single wideband carrier to transport information ladvantages. The presentations are accompanied with an audio narration. I have many books that explain it but each has its own way and do not answer my questions comple.
Abstract long term evolution lte is a significant project of 3rd generation partnership project 3gpp, initially proposed on the toronto conference of 3gpp in 2004 and officially started as lte work item in 2006. This article gives an overview of the main challenges for the. Ofdm forms the basic signal format used within 4g lte. Ofdm ofdma in 4g lte part 1 how can we stream a full hd movies seamlessly. Performance evaluation of lte physical layer using scfdma. The 3gpp did choose the orthogonal frequency division multiple access as the radio access technology due to its simple implementation in receiver, high performance and high spectral efficiency. Lte for umts ofdma and sc fdma based radio access april 2009. Ofdma can also be used as an uplink access scheme, where specific subchannels are assigned to specific ues via mac messages sent on dls. This acronym designates protocols for allowing multiple users to the same radio channel. Myung 2 beyond 3g international mobile telecommunications imt2000 introduced global standard for 3g. Orthogonal frequency division multiple access ofdma is the multiuser variant of the. Key wordslte long term evolution, qos quality of service, prb physical resource block, tti transmit time interval, 3gpp third generation partnership project. Hi, is there any one can help answer the following question. Frequency division multiple access ofdma in downlink dl and single carrier frequency division multiple access scfdma for uplink ul, as shown in figure 3.
Lte employs ofdm for downlink data transmission and scfdma for uplink. Ofdma is the access technique used in longterm evolution lte cellular systems to accommodate multiple users in a given bandwidth. Pdf the lte employs ofdma for downlink data transmission because orthogonal. Tech scholar, gggi dinarpur, india 2assistant professor, gggi dinarpur, india abstract the modern digital transmission systems offer better reliability in noise environment comparing to their analog counterparts. The prime cause of this high speed of lte systems is the advancement in physical layer. Scfdma is widely used in lte subscriber terminals in the transmit path and its variant ofdma is used in the enodeb downlinkor receive path of lte subscribers. It can be explained by packet scheduling scheme like 802. Orthogonal frequency division multiplexing ofdm is a. Umb project, intended as a successor of cdma2000, but replaced by lte. Introduction the rapidly growing demand for high er data rates in wireless c ommunications systems has grown in order to support broadband services.
Myung 6 requirements of lte peak data rate 100 mbps dl 50 mbps ul within 20 mhz bandwidth. This allows simultaneous lowdatarate transmission from several users. 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. Being independent of the powerful access technologies based on cdma and ofdma, multipleinput multipleoutput. Ofdm, orthogonal frequency division multiplex is the basic format used and this is modified to provide the multiple access scheme. Now a days it is a right core technology in wireless. Scalable orthogonal frequency division multiple access sofdma refers to the air interface outlined for portable or mobile wimax systems by ieee, used in ieee 802. Jun 09, 2015 ofdma principles in lte, there are several ways to transmit over the frequency band and to share the resource between several devices. Ofdm technology has been incorporated into lte because it enables high data rates to. Lte, ofdma, scfdma, dft, idft, error rate, bandwidth. Orthogonal frequencydivision multiple access ofdma is a multiuser version of the popular orthogonal frequencydivision multiplexing ofdm digital modulation scheme.
For every advantage engineered, there is always a price. Supporting any mix of voice with data services on the. The various flavors of ofdma are about the demands of mobility and speed of handoffs, the size of the cell, spectrum range, channel sizes, and more. The detailed specification of lte is given in table 1.
593 1189 1084 1177 401 56 223 884 816 106 433 957 1272 525 130 840 530 839 290 671 869 1183 377 316 698 1214 1093 277 464 687 643 794