Introduction to cdma code division multiple access cdma is a radically new concept in wireless communications. The first generation cdma technology has been used in both 2g and 3g mobile cellular standards and it. Fitzek universita di ferraracode division multiple accessfrank h. Fitzek04 february 2003lecture 2the following text is taken partially from my phd thesis. This is done in gsm via gaussian minimum shift keying gmsk. Basic note on spread spectrum cdma signals 4 in the receiver, the received signal is multiplied again by the same synchronized pn code. When they both are used together, they will be termed as 3g cdma. The only reason people are still using cdma services is because it provides better coverage than gsm. Code division multiple access cdma the telecom generations. Code division multiple access cdma is a type of multiplexing that allows various signals to occupy a single transmission channel. By the year 2001 there will be more than 500 million internet users and 600 millions. The whole idea behind cdma technology is to send digital information, ones and zeros, over the air. Thus, there is improved voice and data communication. Towards a comprehensive comparison of ofdm and cdma.
Capacity of cdma systems vijaya chandran ramasami kuid 698659 abstract. Cdma, which stands for code division multiple access, is a competing cell phone service technology to gsm, the worlds most widely used cell phone standard. Now both types of networks are making a transition to thirdgeneration 3g systems around the globe, offering yet more capacity and data services. Perhaps its a good idea to first explain what tdma really means. Overview of cellular cdma vehicular technology, ieee. Overview of code division multiple access technology for wireless. Code division multiple access cdma is a channel access method normally used by 3g radio communication technology as well as in some other technologies. Enhanced services can be provided to cdma one subscribers through cdma2000. Cdma code division multiple access is a secondgeneration digital mobile telephone standard which takes a different approach to the other, competing standards.
Cdma, or code division multiple access, was a standard designed and patented by qualcomm, but subsequently used as the basis for the cdma2000 and wcdma standards for 3g. It is developed by 3gpp2 as a backwardscompatible successor to secondgeneration cdmaone is95 set of standards and used especially in north america and. Time division multiple access is a technique in which different users share access to the radio medium in a dime domain each user gets a time slot during which it is allowed to ei. Multiple users are assigned radio resources using spread spectrum techniques. While understanding the cdma it should be mixed with the different mobile standard with matching names along with the figure around such as.
Pdf the authors present an overview of new multiple access schemes based on a combination of code division and multicarrier techniques. The need to support highspeed burst traffic has already posed a great challenge to all currently available airlink technologies based either on tdma or cdma. We want equal number of two 0s and 1s, a length of three 0s and 1s. After the war ended, qualcomm patented the technology and made it commercially available as a digital cellular technology. Although all users are transmitting in the same rf band, individual users are separated from each other via the use of orthogonal codes. This paper will briefly describe the origins of cdma technology and the emergence of 3g imple. Wideband cdma radio transmission technology the university. The technology is commonly used in ultrahighfrequency uhf cellular telephone systems, bands ranging between the 800mhz and 1. Mc is a family of 3g mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites.
The individual mobile stations cyclically assign a frequency for the exclusive use of a time interval. Several competing digital wireless access technologies including ct2, dect ct3, gsm, tdma, and is95 cdma have been used for providing the low tier and. Cdma technology has given significant advantages over other parallel technologies in. Future wireless communication systems should be operating mainly, if not completely, on burst data services carrying multimedia traffic. Cdma, code division multiple access an implementation of direct sequence spread spectrum, dsss, and was used almost universally for 3g mobile communications standards as it provided an excellent format as a multiple access scheme. It has gained widespread international acceptance by cellular radio system operators as an upgrade that will dramatically increase both their system capacity and the service quality. Code division multiple access cdma is a sort of multiplexing that facilitates various signals to occupy a single transmission channel. The first generation cdma technology has been used in both 2g and 3g mobile cellular. Cdma is a form of spreadspectrum, a family of digital communication techniques that have been used in military applications for many years. Professor, quantum school of technology, mandawar, roorkee dehradun highway, roorkee, uk. Cdma can be implemented in several ways, two of which are frequency hopping and direct sequencing.
In the past decade, it has been shown that cdma is the most suitable multiple access transmission technology for mobile communications and all the. The receiver, knowing the code sequence of the user, decodes the received signal and recovers the original data. Cdma, like gsm, has seen incremental improvements in capacity throughout this period. In 1985, the fcc allocated three frequency bands to spread spectrum communications. Introduction to code division multiple access cdma duration. The generation is generally utilized in ultraexcessivefrequency uhf cellular smartphone systems, bands ranging among the 800mhz and 1. What is code division multiple access 2000 cdma2000. Cdma technology in cdma tutorial 03 may 2020 learn cdma. Cdma technology is known as a spreadspectrum technique which allows many users to occupy the same time and frequency allocations in a given band and space. Code division multiple access cdma technology was chosen for the air interface of the upcoming third generation wireless systems 3g.
The preferred technology for thirdgeneration systems depends. Prasad, overview of air interface multiple access for imt. Cdma is95 code division multiple access global telecoms. Incremental progress 1g amps data capabilities 30 khz. For cdma spreading code, we need a random sequence that passes certain quality criterion for randomness. Time division multiple access tdma is a complex technology, because it requires an accurate synchronization between the transmitter and the receiver.
The speech quality provided by the cdma systems is far superior to any other digital technology particularly in difficult radio environments such as dense urban areas and. The development of code division multiple access cdma enabled thirdgeneration 3g mobile system is also. Nov 15, 2016 code division multiple access cdma is a digital cellular network standard that utilizes spreadspectrum technology. I have seen it myself that in crowded and conjusted area. Cdma2000 builds on the inherent advantages of cdma technologies and introduces other enhancements, such as orthogonal frequency division multiplexing ofdm, advanced control and signaling mechanisms, improved interference management techniques, endtoend. The next generation cdma technologies hsiaohwa chen. The analysis of power control schemes in cdma is an original work.
The 3x standard has now been superseded by a twophase strategy called cdma2000 1xev. In this paper defined an overview of cdma correlation techniques in 3g systems. So, in the us the fcc settled on a dualmode route that required either gsm or cdma. Lee, fellow, ieee abstractthis paper is a general description of code division multiple access cdma. Such standards included cdma ds, cdma mc, and some tdd technologies. Introduction to spread spectrum technology cdma ds. Nov 24, 2019 cdma, which stands for code division multiple access, is a competing cell phone service technology to gsm, the worlds most widely used cell phone standard. Cdma i about the tutorial code division multiple access cdma is a channel access method normally used by 3g radio communication technology as well as in some other technologies. It uses multiplexing techniques including code division multiple access cdma as well as timedivision multiple access to maximize both individual. This technology does not constrict bandwidths digital signals or frequencies but spreads it over a fullyavailable spectrum or across multiple channels via division. It is known that ofdm and cdma modulation techniques are used in modern wireless. On 7 november 1989, qualcomm publicly demonstrated a digital cellular radio system based on code division multiple access cdma spread spectrum technology, which increased capacity, improved service quality, and extended battery life. They were both developed in the early nineties for 2g connectivity. You can find the guidelines for evaluation, known as m.
Code division multiple access cdma is a digital cellular network standard that utilizes spreadspectrum technology. Cdma stands for the code division multiple access its basically the telecommunication technology that is use by the various radio communicating companies for accessing the channels in the minimum time. Capacity of a cellular cdma, ieee transactions on vehicular technology, vol. Gsm global system for mobile communications and tdma time division multiple access. Introduction to code division multiple access cdma. Cdma 2000 is mostly an orthogonal cdma system gold sequences have only three crosscorrelation peaks, which tend to get less important as the length of the code increases. Ds cdma, cdma2000, mc cdma and mimo cdma 2,3 are the different versions of same technology. Invented by hedy lamarr and george antheil in the 1940s, it was used to control the movement of torpedoes by means of using multiple radio frequencies. Youve probably heard of these acronyms when you were told that you cant use a certain phone on your mobile network because theyre using different technologies that are not compatible. Basics idea about cdma technology and its applications. This technology makes optimal use of available bandwidth and is based on spread spectrum technology. Communication and cdma code division multiple access.
Cdma technology and its several versions are also popular for communication. Cdma2000 1xevdo evolutiondata optimized, often abbreviated as evdo or ev, is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband internet access. Explaining cdma codedivision multiple access technology is very difficult as it involves some pretty complex math. Cdma, ask latest information, abstract, report, presentation pdf,doc,ppt,cdma technology discussion,cdma paper presentation details,cdma, ppt, pdf, report. Cdma code division multiple access or cdma has its roots in wwii era spread spectrum technology. Code division multiple access cdma is a digital technique for sharing the frequency spectrum. It is cellular technology in which there are two main systems viz. The bandwidth of the coded data signal is chosen to be much larger. Individual conversations are encoded with the help of pseudorandom digital sequence.
Codedivision multiple access cdma is a channel access method used by various radio communication technologies. Cdma is a wireless transmission technology that was developed during world war ii by the english allies to avoid having their transmissions jammed. Cdma, ask latest information, abstract, report, presentation pdf,doc,ppt, cdma technology discussion, cdma paper presentation details, cdma, ppt, pdf, report. But engineers couldnt agree on which one was the best.
The cdma technology was then adopted as the national standard and the cdma mobile systems cms. Abdullah and others published an overview of cdma techniques for mobile communications find, read and. It can also be exploited for a wide range of applications including range measurement, material penetration and low probability of interception. Development of cdma for cellular communications, 1989. Gsm and cdma are different technologies that phones use to connect. This allows several users to share a band of frequencies see bandwidth. Code division multiple access 2000 cdma2000 is a third generation 3g standard developed by the international telecommunication union itu. They also have a single autocorrelation peak at zero, just like ordinary pn sequences. Gold sequences are in useful in nonorthogonal cdma. Pdf an overview of cdma techniques for mobile communications. The technicality of cdma technology has given significant advantages over other parallel technologies in terms of spectrum efficiency and overall performance. An overview of code division multiple access cdma applied to. However, the main focus is to differentiate between 3g and cdma.
Cdma is a modulation and multiple access scheme based on spread spectrum communications techniques, a well established technology that has been. It represents the endto end wireless system and all the necessary specifications that govern its operation. This protocol uses cdma access to send voice and data and signals between mobile phones and cell sites. In second and third generation wireless communication a protocol named cdma came into existence. The core principle of spread spectrum is the use of noiselike carrier waves, and, as the name implies, bandwidths. Cdma is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. Towards a comprehensive comparison of ofdm and cdma techniques dimitrios a.
The itur went through an evaluation process of them all. As very important key technologies of beyond 3g systems, mc cdma is the method combined ofdm and cdma has being received more and more attention recently, because it can provide many advantages, such as larger capacity, high data rate, frequency and time diversity, etc. The core principle of spread spectrum is the use of noiselike carrier waves, and. Ijcat international journal of computing and technology, volume 1, issue 8, september 2014 issn. Cdma2000 represents a family of imt2000 3g standards providing highquality voice and broadband data services over wireless networks. Tdmafdma, cell frequency planning is more tedium task as frequency and time planning need to be carried out in cdma frequency planning is minimal. Brief summary about cdma technology and how it is used. These two technologies differ in the way calls and data travel over the mobile phone networks. This report presents an overview of the capacity of code division multiple access cdma systems.
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