Phil flikkemas usf briefing introduction to spread spectrum pdf about the capacity of a ds spread spectrum cdma cellular system pdf overview of modulation techniques for wireless pdf. Figure 1 a binary information signal to modulate this signal, we would multiply this sequence with a sinusoid and its. The voice has to be digitalize pulse code modulation pcm then compressed each user is given a unique pn code. 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. Cdma2000 represents a family of imt2000 3g standards providing highquality voice and broadband data services over wireless networks.
Ericsson products are scheduled for delivery in late 2002 as part of cms 11 r4. An introduction to the access technologies that allow multiple users to share a common communications channel. 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. The umts world is an 3g mobile system news and information provider. A free powerpoint ppt presentation displayed as a flash slide show on id. Cdma code division multiple access or cdma has its roots in wwii era spread spectrum technology. This video explains the lte technology basics, ofdma and lte frame structures and types. So cdma is known to cover more area with fewer towers. Soft handoff a soft handoff is applied to an ms that starts communication with a new bts while still connected to another bts makebeforebreak hard handoff a ms is disconnected from one bts and is switched to another breakbeforemake softer handoff a special soft handoff between sectors in the same bts idle handoff an idle handoff is. Cdma and mc dscdma are the same as wide as that dscdma, and the mtcdma schemes has almost the twice bandwidth as the dscdma scheme. The receiver, knowing the code sequence of the user, decodes the received signal and recovers the original data. This cdma tutorial describes cdma basics by explaining pn sequence codes, walsh codes,cdma physical layer for base station and mobile subscriber.
Cdma issues so far, cdma looks like a step backwards. Codedivision multiple access cdma is a channel access method used by various radio communication technologies. Learn how to use powerpoint for mac, from beginner basics to advanced techniques, with online video tutorials taught by industry experts. Communication systems following this concept are spread spectrum systems. While in landline based telecommunication systems the users can be very conveniently divided by independent wire lines,in cellular communications since the medium of communication is air interface the subscribers have to be separated with respect to the radio frequency that they are using for. Access method cdma cdma code division multiple access qall terminals send on same frequency at the same time using all the bandwidth of transmission channel qeach sender has a unique random number, sender xors the signal with this random number qthe receiver can tune into this signal if it knows the pseudo random number disadvantages.
Nov 12, 2014 the major difference between wire line and wireless networks is the choice of access techniques. The major difference between wire line and wireless networks is the choice of access techniques. Similarly, a combination of open loop and closed loop power control is used on the forward link downlink to keep snr at the mobile almost constant. What is frequency hopping code division multiple access. Cdma is the short form of code division multiple access.
Jeanpaul linnartz, 2007 cdma the basics of code division multiple access jeanpaul m. Individual conversations are encoded with the help of pseudorandom digital sequence. Cdma2000 success story in japan as of nov, 2003 total 3g sub. Cdmabased mac protocol for wireless ad hoc networks.
Fundamentals of 3g basics of wcdma for umts duration. Lte basics part i ofdma and lte frame structures youtube. Presentation layer is basically a means of data definition and preparation before. Code division multiple access each user is assigned a binary, direct sequence code during a call. The technicality of cdma technology has given significant advantages over other parallel technologies in terms of spectrum efficiency and overall performance. While in landline based telecommunication systems the users can be very conveniently divided by independent wire lines,in cellular communications since the medium of communication is air interface the subscribers have to be separated with respect to the radio frequency that they are using. They also have a single autocorrelation peak at zero, just like ordinary pn sequences. Cdma basics free download as powerpoint presentation. The advanced transmission techniques of ofdm, applied in wireless lans and in digital and video broadcasting, and cdma, the foundation of 3g mobile communications, have been part of almost every communication system that has been. Basic diagram of cdma there exist a new dimension with time and frequency. Fdma, tdma, cdma, ofdma, and sdma an introduction to the access technologies that allow multiple users to share a common communications channel. Basics idea about cdma technology and its applications. Computer programming concepts and visual basic ebook free download pdf. Tight synchronization is required to use orthogonal codes, which then break in a multipath channel anyway quasiorthogonal codes cause selfinterference, which dominates the performance in most cdma systems nearfar problem is a serious hindrance, requiring fast and.
Lets take a simple analogy to understand the concept of cdma. But, the downlink detection strategies for mt cdma and mc dscdma havent proposed yet. It is used to cover wide area and used to provide higher throughput. Basics of cdma basic properties of cdma systems basic properties of cdma systems cdma is one of the applications of spread spectrum communications which is used in civilian, commercial and military communication. Technical introduction to cdma course outline basic cdma principles coding forward and reverse channels cdma operational details multiplexing, forward and reverse. Ppt technical introduction to cdma powerpoint presentation. Microsoft powerpoint 2016 is primed for use on tablets and phones, so you can swipe and tap your way through presentations.
In code division multiple access cdma systems all users transmit in the same bandwidth. Fundamentals of communications access technologies. The advanced transmission techniques of ofdm, applied in wireless lans and in digital and video broadcasting, and cdma, the foundation of 3g mobile communications, have been part of almost every communication system that. Multiple users occupying the same band by having different codes is known as cdma code division multiple access system let w spread bandwidth in hz r 1tb date rate s received power of the desired signal in w j received power for undesired signals like multiple access users, multipath. Features of cdma one,wireless and mobile communication,free pdf download. The basics of code division multiple access jeanpaul m. In 1985, the fcc allocated three frequency bands to spread spectrum communications. Multiple accesses multiplexing for short enable multiple signals to occupy a single communications channel. Frequency hopping code division multiple access fhcdma is a basic modulation technique used in spread spectrum signal transmission. Umts overview david tipper associate professor graduate telecommunications and networking program university of pittsburgh 2720 slides 12 telcom 2720 2 umts etsi proposed gsmnatdma gprs evolution under name universal mobile telecom. Here, multiple access is explained with the example of wifi hotspot.
This is a brief tutorial that describes all the technical terms in a simple language to make it understandable for all the interested readers. Introduction to cdma code division multiple access cdma is a radically new concept in wireless communications. It is the technique by which same frequency and time interval is used by mobile subscribers base stations by way of unique digital codes. This allows several users to share a band of frequencies see bandwidth. Prepared by ibrahim alobida 816 code division multiple access cdma cdma features. There is no restriction on time and frequency in this scheme. There are many features which make the new powerpoint attractive. 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. Gold sequences are in useful in nonorthogonal cdma. This helps to reduce the strength of electronic warfare, that is, the.
Cdma is the base on which access methods such as cdmaone, cdma2000, and wcdma are built. Home of rf and wireless vendors and resources rf wireless world. Mac protocol for a wireless lan based on ofdmcdma article in ieee communications magazine 389. Cdma2000 cdmaone figure 1 cdma standards evolution. Alaa muqattash and marwan krunz department of electrical and computer engineering the unniversity of arizona. Microsoft powerpoint 2016 for mac free download and. Cdma as one of the major problems facing the development of telecommunications, bandwidth demand has driven the search for protocols that could be used to maximize bandwidth efficiency. All the users can transmit at all times and at all frequencies. Also severe problem for cdmanetworks precise power control needed. All users use same frequency and may transmit simultaneously narrowband message signal multiplied by wideband spreading signal, or codeword each user has its own pseudocodeword orthogonal to others.
The ds code is a signal generated by linear modulation with wideband pseudorandorn noise pn sequences. Services umts most of 3g licenses in europe required operator to deploy. There are several way by which we can use multiple access technique such as tdma, fdma, cdma, wcdma, sdma, ofdma, scma. Fdma, tdma, cdma, ofdma, and sdma an introduction to the access technologies that allow multiple users to share a. 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. The pcs1900 licenses already cover approximately half of the us population, and it is likely that this will increase to close to full coverage as remaining li t d. Cdma cellular systems are deemed superior to fdma and tdma, which is why cdma plays a critical role in building efficient, robust, and secure radio communication systems. Mac protocol for a wireless lan based on ofdmcdma request pdf. For the detection methods, a lot of strategies have been proposed for downlink channel of mccdma. Cdma can be implemented in several ways, two of which are frequency hopping and direct sequencing. In code division multiple access cdma systems all users transmit in the same bandwidth simultaneously. As a result, ds cdma uses much wider signals than those used in other technologies. The new dimension represent the code which provided by the operator for the user. Comprehensive coverage of umts 3g news, licensing, business developments, 3g wcdma telecommunication technology, multi media mobile phones and future communications.
Jeanpaul linnartz, 2007 cdma outline multiple access methods fdma, tdma, cdma spread spectrum methods frequency hopping direct sequence more on code sequences. View tdma, cdma,fdma ppts online, safely and virusfree. The bandwidth of the coded data signal is chosen to be much larger. Introduction fdma is the division of the frequency bands allocated for wireless cellular telephone communication into channels. Because users are isolated by code, they can share the same carrier frequency, eliminating the frequency reuse problem encountered in other technologies. Physical and medium access control mac for ieee 802. Cdma is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. 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. Global reach gsm is in use over 80% of the worlds mobile networks in over 210 countries as compared to cdma.
To permit this without undue interference between the users, cdma. Powerpoint for mac online courses, classes, training. Giunta for the academic course of digital signal processing of the third university of rome rome, may 2000. Code division multiple access cdma linkedin slideshare. 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. Code division multiple access cdma the concept of signal spreading and its uses in communications lets take a stright forward binary signal of symbol rate 2. It is used to designate fifth generation of mobile technologies. The evolution of cellular technologies from offering only voice services to enabling mobile data services took a major milestone after the introduction of third generation 3g networks.
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