It is necessary to ensure that the data is carried efficiently over the available spectrum, and therefore maximum use is made of the available spectrum, and hence the. Also see cdma, cdma one, and cdma2000 w cdma wideband codedivision multiple access, an itu standard derived from codedivision multiple access, is officially known as imt2000 direct spread. The transmitted data is demodulated back to its original form at the receiving end. Performance evaluation of digital modulation techniques on. What is wideband code division multiple access wcdma. The move to digital modulation provides more information capacity, compatibility with digital data services, higher data security, better quality communications, and quicker system availability. Wcdma hspa basics for umts kari aho project and business development manager kari. Wcdma uplink physical channel uplink data is carried on the dedicated physical data channel dpdch and different data rate is realized using different spreading factor. Long and short type of scrambling codes are available.
This tutorial on umts covers spreading, scrambing and modulation concepts. Spreading, modulation and other physical layer procedures measurements and their provision to the upper layers ran2 covers, for instance. Tdscdma modulation overview principles of tdscdma time division synchronous code domain multiple access tdscdma time division synchronous code domain multiple access is a multiple access technology, which is a combination of code division multiple access cdma and time division multiple access tdma. All about modulation basic concepts, signal space, constellations and phase shift keying modulations psk, qpsk, oqpsk, mpsk. Modulation is the process of changing the parameters of the carrier signal, in accordance with the instantaneous values of the modulating signal. In ask the amplitude of the carrier signal is modified by the digital signal. The most major difference between cdma and wcdma is in the group of technology that it is grouped with. A tutorial, or overview of the basics of the umts, wcdma modulation formats or schemes used. To demonstrate these points, lets examine the uplink and downlink paths of a wcdma system, as specified in the 3gpp standard ts 25. It also mentions tutorial links on gsm and cdma useful to derive further difference between gsm and cdma. Coverage of wcdma network using different modulation techniques with soft and hard decision decoder 1. Digital modulation in communications systems an introduction. These modulation techniques are the basis of communications for systems like cable modems, dsl modems, cdma, 3g, wifi ieee. Rf lecture series modulation fundamentals introduction to.
Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. Umts system architecture ue user equipment that interfaces with the user utran umts terrestrial radio access network handles all radio related functionality wcdma is radio interface standard here. The first is the channelization operation, which transforms every data symbol into a number of chips, thus increasing the bandwidth of the signal. Recall that our goal is to transmit data over a commu nication link, which we achieve by mapping the. Wcdma was chosen as 3g technology in late 1997early 1998 by many forums like european telecommunications standards institute etsi. Cn core network is responsible for transport functions such as switching and routing calls and data, tracking users usim me. Hapter modulation and demodulation mit opencourseware.
The total number of phase quadruples is 2 s1 and s2. They have been developed to support voice as well as data communications between various subscribers located across the world. It only helps in separating signals from different sources. The application of the heterodyne principle to modulation is shown schematically in figure 143. The third generation 3g cellphone technology called wideband cdma wcdma uses a similar method with compressed voice and 3.
W cdma wideband codedivision multiple access, an itu standard derived from codedivision multiple access, is officially known as imt2000 direct spread. Example of how the data from three different users is spread using codes, combined and sent as a single waveform, and then how the data from each user is recovered using each userspecific code. Fundamentals of communications access technologies. Multilevel simulation of wcdma systems for thirdgeneration. Wcdma was adopted as a standard by the international mobile telecommunications. Scrambling using scrambling code scrambling does not change the bit rate.
The two components are summed in a modulator circuit. The left and right channels each limited to 15khz are multiplexed into a single baseband signal using amplitude modulation using frequency modulation to shift the baseband. The show transport channel settings check box enables you to specify the parameters corresponding to the wcdma tx channel coding scheme subsystem, the wcdma tx phch mapping subsystem, and its corresponding subsystems at the receiver side. A high speed 3g mobile wireless technology with capacity to offer higher data rate than cdma. Being wider than its competition cdma2000 which only used a 1. Input signal contains envelope and phase information.
Types of modulation 6 flynnkatz 7810 analog modulation amplitude modulation, am frequency modulation, fm double and single sideband, dsb and ssb digital modulation phase shift keying. Developers of communications systems face these constraints. From basics to adaptive trelliscoded, turboequalised and spacetime coded ofdm, cdma and mccdma systems by l. This chapter describes the essential principles behind. Umts spreading scrambling modulation umts tutorial. Wcdma signal eer wcdma signal is both amplitude and phase modulated contains am of cdma signal. Pdf universal mobile telecommunication systemumts is the. Wcdma is a 3g technology that is often used in tandem with gsm to provide both 2g and 3g capabilities within the same area of coverage. Different modulation methods corresponding to different transmitting abilities in air interface.
Generally, the modulation format of the rf demodulator follows the modulator. The baseband signals are incompatible for direct transmission. Codedivision multiple access cdma techniques using direct sequence ds spread spectrum techniques were embodied in the is95a cellular standard and are now the clearly accepted choice for thirdgeneration cellular 3g and pcs applications. Wcdma are widely described in 8 and in 3gpp specifications 7. Hsdpa and hsupa were introduced in 3gpp release 5 and 3gpp release 6, respectively. Due to coherent modulation, each users uplink requires an individual channel estimation. Second generation cellular cdma systems use what is called dual bpsk for.
Wcdma provides the ability to dynamically assign data rates and modulation format to match the individual user demand. Using amplitude modulation to shift the baseband signal fm radio 88mhz108 mhz. Spectrum inversion in ncdma to ensure compliance with. Modulation is the process of transforming the input data into a suitable format for the transmission medium. Overrides the automatic modulation detection and lets you specify the downlink hs pdsch or the uplink edpdch modulation scheme, to be used with the despread code channel for channel measurement results.
Wcdma spreading and modulation stanford university. This name was often used to refer to the whole system. Oct 31, 2016 16qam and 64qam have much tighter constellations than qpsk, so in order to use them you will need much better ci and consideration of multipath in order to be able to distinguish the symbols. Emphasis is placed on explaining the tradeoffs that are made to optimize efficiencies in system design. You must know wcdma which stands for wide band code division multiple access.
Systems beyond imt2000 imtadvanced is set to introduce evolutionary path beyond 3g. As qpsk is used for the modulation of the syncdl, the phases 5, 45, 225, 5 and 315, 225, 315, 45 are used. The proposed 3g wideband cdma systems are complex in nature. Wcdma has the capacity to easily handle bandwidthintensive applications such as video, data, and image transmission necessary for mobile internet services. Modulation scheme chooses how the vsa demodulates the hs pdsch high speed physical downlink shared channel corresponding to one channelization code of fixed. In case the presence of a pccpch is indicated, the next following subframe is the first subframe of the interleaving period. Uplink and downlink packet evolutions, hsupa and hsdpa respectively, to wcdma are introduced in detail in 8, 9 and 10. International journal of computer networking and communication ijcnacvol.
All about modulation part i basic concepts, signal space, constellations and phase shift keying modulations psk, qpsk, oqpsk, mpsk. Wideband code division multiple access wcdma is a thirdgeneration 3g standard that employs the directsequence code division multiple access dscdma channel access method and the frequencydivision duplexing fdd method to. Bpsk, qpsk, msk frequency shift keying, fsk quadrature amplitude modulation, qam. Each radio station is assigned 200 khz, to transmit a stereo audio. W cdma is a thirdgeneration 3g mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in todays market. One modulation technique that lends itself well to digital processes is called iq modulation, where i is the inphase component of the waveform, and q represents the quadrature component. Second generation 2g mobile communication standards were developed to provide higher bandwidth efficiency, security and digital modulation schemes. Pdf performance analysis of qpsk modulation technique in. Modulation modulation is the process of transforming the input data into a suitable format for the transmission medium. However, nokia and erickson have just signed an agreement with tmobile to upgrade to 3 rd generation wcdma from gsm. Rf lecture series modulation fundamentals introduction to wcdma.
When the box is selected, the dialog displays the following parameters. Parameters power control open and fast closed loop multirate variable spreading 4256 soft handover interfrequency handover handover qpsk bpsk fdd qpsk qpsk tdd modulation scheme dlul intercell synchronization asynchronous duplex scheme fdd and tdd carrier spacing flexible with 200 khz. Spectrum inversion in ncdma to ensure compliance with 3gpp2. Wideband code division multiple access wcdma is a thirdgeneration 3g standard that employs the directsequence code division multiple access dscdma channel access method and the frequencydivision duplexing fdd method to provide highspeed and highcapacity service. The gsm uses gaussian minimum shift keying gmsk modulation method. Using this bandwidth it has the capacity to carry over 100 simultaneous voice calls, or it is able to carry data at speeds up to 2 mbps in its original format. Myung 2 beyond 3g international mobile telecommunications imt2000 introduced global standard for 3g. We considered an example of amplitude modulation in chapter 6 that does this. For such a signal, to travel longer distances, its strength has to be increased by modulating with a high frequency. Basic wcdma studies1 free download as powerpoint presentation. 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. W cdma systems can employ the high order modulation mpsk or mqam to increase the transmission data rate with the link quality control. Wcdma is wideband cdma that still uses code division to divide the channels.
Applying spread spectrum modulation techniques to cellular communications allows for multiple users to share common spectrum. Meassetup w cdma3gpphspa demod properties channellayer tab default. Difference between cdma and wcdma difference between. Both the gsm and cdma are cellular wireless technologies. In its various forms, iq modulation is an efficient way to transfer information, and it also works well with digital formats.
Qpsk or 16qam the utran air interface uses qpsk modulation in the downlink, although hsdpa may also employ 16 quadrature amplitude modulation 16qam. Spreading principle user information bits are spread into a number of chips by multiplying them with a spreading code the chip rate for the system is 3. Mobile class targets 100 mbps with high mobility and nomadic local area class targets 1 gbpswith low. It is a third generation network developed by ntt docomo and from 2g network cdma.
Principles of communication modulation tutorialspoint. There are three basic ways to modulate a carrier signal in a digital sense. This tutorial on umts covers spreading, scrambing and modulation concepts scrambling using scrambling code scrambling does not change the bit rate. This and the data transport format is carried on thededicated physical. Coverage of wcdma network using different modulation techniques with soft and hard decision decoder j. Wcdma rf output envelope pa final stage and dsp i q downcon adc experimental envelope tracking amplifier high power rf stage f 2.
Wcdma wide band code division multiple access umts before we talk about 4g or gsm. Coverage of wcdma network using different modulation. Then the signal is multiplied by the carrier which is the second modulation. What is wcdma wideband codedivision multiple access. A datamodulation scheme defines how the data bits are mixed with the carrier signal, which is always a sine wave. Cdma is a 2g technology and is a direct competitor to gsm, which is the most widely deployed technology.
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