The basic difference between gsm and cdma is that the gsm is a sim specific i. 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. The short code used in cdma system is based on a msequence created from a lfsr of 15 registers of length 215 1 32,767 codes. These papers concede that cdma networks are interference and reverselink limited in that the system ca.
Cdma uses spreadspectrum technology to minimize the problems. Wcdma wideband code division multiple access it uses the dscdma channel access method and the fdd duplexing method to achieve higher. The user of this ebook can download, read, print, or keep it for hisher. The gsm network identifies each cell via the cell global identity cgi number assigned to each cell. Theyre ways for people to cram multiple phone calls or internet connections into one radio channel. Comments on the national toxicology program bioassay on. Data transfer speed if you plan to use your cell phone or cellular terminal for more than voice transmission including surfing the web, downloading photos or transmitting video cdma is generally preferred because of its faster data transfer speed compared to gsm. Code division multiple access cdma is a digital air interface standard, claiming eight to fifteen times the capacity of analog. Fdma and tdma usually need reuse factors of 4 7 capacity increased 47 fold. Gsm phones always included a sim card slot and cdma cell phones lacked them. Frequency hopping is the easiest spread spectrum modulation to use.
The goal is to dramatically increase the number of essentially simultaneous users within a specific portion of radio spectrum. The whole idea behind cdma technology is to send digital information, ones and zeros, over the air. Although not available code channels are 64, it may not be possible to use a single time, since the cdma frequency is the same. Time division multiple access tdma is a more complex technique, for it needs a highly accurate. This information is sent by the mobile unit to the msc. The cell is the area given radio coverage by one base transceiver station. As a general note, the draft bioassay uses the terms mobile phone and cell phone interchangeably, and one term should be used consistently. Cdma is an example of multiple access, which is where several transmitters can send information simultaneously over a single communication channel multiple access in cdma. Gsm and cdma are competing wireless technologies with gsm enjoying about an 82% market share globally.
If multiple users transmit a spreadspectrum signal at the same time, the receiver will still be able to distinguish between users, provided that each user has a unique code that has a sufficiently low crosscorrelation with the other codes. Gsm and cdma are the most successful cell phone technologies present in world, cdma handsets are chip based where as gsm handsets uses sim cards, using. Gsm and cdma are the most successful cell phone technologies present in world, cdma handsets are chip based where as gsm. Cdma and gsm are both multiple access technologies. The worlds renowned mobile phone network technologies are gsm global system for. In 3g, the most prevalent technology was umts with cdma2000 in close contention all radio access technologies have to solve the same problems. It connects to the service providers network via broadband such as dsl or cable. Enhanced services can be provided to cdma one subscribers through cdma2000. Communication and cdma code division multiple access. Before explaining our comments on the current draft, as a general matter we wish to point out that the ntp bioassay on rf evaluates gsm and cdma technology but does. Cellular technology is what mobile phone networks are based on, and its the technology that gave mobile phones the name cell phones. Small cell technology small cell networks qualcomm. So, cdma capacity calculations should be very simple. Its hard to keep up with the 2gs and the 4gs and the xltes of the world.
What is code division multiple access 2000 cdma2000. Cdma cellular systems are deemed superior to fdma and tdma, which. Individual conversations are encoded with the help of pseudorandom digital sequence. Simplify all types of small cell deployment scenarios with ultrason technology from qualcomm technologies, inc. Cdma technology has given significant advantages over other parallel technologies in. The msc verifies the information and connects to the unit to the cell while it. Mobile cellular technologies explained daniel miessler. A broader term which is more widespread in the industry is small cell, with femtocell as a subset. The forward channel is the direction of the communication or mobiletocell.
If a user wished to upgrade to a new cell phone, it meant contacting the carrier through its customer service line and having their old phone. Ideally, tdma and cdma are transparent to each other. Short message service center or smsc the node that stores and forwards short messages to and from the. For browsing the web, to watch videos and to download music, cdma.
This is exclusively available in cdma technology only. This technology makes optimal use of available bandwidth and is based on spread spectrum technology. The technology is commonly used in ultrahighfrequency uhf cellular telephone systems, bands ranging between the 800mhz and 1. Comparisons of fdma, tdma, and cdma example control channelscell 2 2 2 capacity vs fdma 1 4 16. Basics idea about cdma technology and its applications. Performance analysis of cdma wll systems with imperfect. Using a scheme known as direct sequence spread spectrum, different ues have different codes and can all talk to the base station even though they are all on the same frequency. Cellular technology enables mobile communication because they use of a complex. Cellular technology basically refers to having many. Difference between gsm and cdma with comparison chart. Wireless local loop wll provides reliable, flexible, and economical access to the local telephone service using radio technology in the place of traditional wireline. In second and third generation wireless communication a protocol named cdma came into existence.
To permit this without undue interference between the users, cdma. 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. This tutorial provides a basic overview of cdma in a userfriendly way. But the two competing technologies differ in the way user sharing the common resource. 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 prof. Wide band cdma technology is selected for utran air interface. Code division multiple access 2000 cdma2000 is a third generation 3g standard developed by the international telecommunication union itu. In telecommunications, a femtocell is a small, lowpower cellular base station, typically designed for use in a home or small business. But the big question on the minds of engineers, manufacturers, and anyone else involved in iot is. Comparison of cdma and gsm mobile technology article pdf available. The gateway msc or gmsc the purpose of which is to query the hlr and determine the location of the subscriber. What does the cdma phaseout mean for my companys iot strategy in the longterm.
Cdma2000 also known as imt multicarrier imtmc is a family of 3g mobile technology standards, which use cdma channel access, to send voice, data, and signaling data between mobile phones and cell sites. Understanding the difference between gsm and cdma will allow you to choose a carrier that uses the preferable network technology for your needs. With the fast development in signal processing, it has become feasible to use the technology for wireless. All three principles allow multiple users to share the same physical channel. In 2010, carriers worldwide switched to lte, a 4g network that supports simultaneous voice and data use. The gsm association is an international organization of cellular carriers founded in 1987, provide coverage worldwide using the european etsi wireless standard gsm. Cdma networks that outperforms traditional techniques. In this paper, an analytical model is derived to evaluate the effect of both imperfect power control and imperfect sectorization on the performance of code division multiple access cdma wll systems. Multicell cdma network design vehicular technology, ieee. On the other hand, in cdma the network identifies a handset by the information stored in the internal memory and hence, its handset specific. Cdma technology is the basis for interim standard 95 is95 and operates in both the 800mhz and 1900mhz frequency bands. These codes are used for synchronization in the forward and reverse links and for cellbase station identification in the forward link.
Tdma allows the users to share the same frequency channel by dividing the signal into different time slots. In practice, highpower cdma signals raise the noise floor for tdma receivers, and highpower tdma signals can cause overloading and jamming of cdma receivers. Pdf many digital cellular and mobile systems are in use today. These are two very different methodologies use to accomplish the same task, use frequency spectrum much more efficiently than the traditional dedicated fixed frequency transmitting system. This allows several users to share a band of frequencies see bandwidth. 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. This protocol uses cdma access to send voice and data and signals between mobile phones and cell sites.
Remember tuning the dial and picking up a cell phone call. In general, this means that cdma is a standard for handsets, along with a phone number assigned for a particular phone. Whereas, cdma stands for code division multiple access. But the term cdma is also commonly used to refer to one specific family of.
Cdma stands for code division multiple access, so what were trying to do is to allow multiple independent streams of digital data. Base stations are referred to as nodeb and control equipment for. Cdma is a wireless transmission technology that was developed during world war ii by the english allies to avoid having their transmissions jammed. The worlds renowned mobile phone network technologies are gsm global system for mobile. Cdma technology has given significant advantages over other parallel. Global system for mobile communications gsm, around 8085% market share and is95 around 1015% market share were the two most prevalent 2g mobile communication technologies in 2007. One major problem in cdma technology is channel pollution, where signals from too many cell sites are present in the subscribers phone but none of them is dominant. When a unit is about to leave one cell area and travel to another it seeks out the strongest cell signal it can find. The cdma technology was then adopted as the national standard and the cdma mobile systems cms. Code division multiple access cdma is a sort of multiplexing that facilitates various signals to occupy a single transmission channel.
Development of cdma for cellular communications, 1989 citation. Code division multiple access cdma is a channel access method used by various radio communication technologies. Cdma is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. Introduction to cdma code division multiple access cdma is a radically new concept in wireless communications. These two technologies differ in the way calls and data travel over the mobile phone networks.
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