Cellular Network Basics Frequency Division Multiple Access (FDMA); Time Division Multiple Access (TDMA); Code Division Multiple Access (CDMA). 3G CDMA – WCDMA and cdma Rodger E. Ziemer. IEEE Communications Society. Distinguished Lecturer Program. May June1, 2. Rules for. Preface Code division multiple access (CDMA) has proven itself to be a viable technique for enabling the simultaneous transmission and reception of data over .

Author: Mezishicage Felmaran
Country: Switzerland
Language: English (Spanish)
Genre: Business
Published (Last): 11 April 2012
Pages: 177
PDF File Size: 1.24 Mb
ePub File Size: 8.96 Mb
ISBN: 580-8-20175-676-1
Downloads: 93793
Price: Free* [*Free Regsitration Required]
Uploader: Guramar

The bandwidth of the CDMA spread spectrum signal will be much wider than the original data stream. This would have appeared as noise in the system.

Its development lead xdma to the CDMA series of standards. Each bit in the spreading sequence is called a chip, and this is much shorter than each information bit. Data produced by other dispreading codes would appear as noise and can be discarded as it would be lower in value. The resulting data stream has a higher data rate than the data itself.

CDMA Tutorial | Code Division Multiple Access Basics |

The spreading sequence or chip sequence has the same data rate as the final output from the spreading multiplier. In this way a base station can communicate with several mobiles on a single channel. It has a number of distinguishing features that are key to spread spectrum transmission technologies:. Vasics electronics technology improved, it started bascis be used for covert military transmissions in view of the facts that the transmissions look like noise, it is difficult to decipher without the knowledge of the right codes, and furthermore it is difficult to jam.

CDMA technology gave some significant advantages when compared to the technologies used for previous in terms of overall performance and specifically in terms of spectrum efficiency. Power absics RF technology Test Wireless. As a result this it was possible to start writing a specification for CDMA in This enabled the process to be visualised more easily. To decode the signal and receive the original data, the CDMA signal is first demodulated from the carrier to reconstitute the high speed data stream.


Direct sequence spread spectrum is a form of transmission that looks very similar to white noise over the bandwidth of the transmission. This is because, signals with filety;e data rates occupy wider signal bandwidths than those with low data rates. Essentially Fiketype is a form of spread spectrum transmission which uses spreading codes to spread the signal out over a wider bandwidth then would normally be required.

Similarly several mobiles can communicate with a single base station, provided that in each case an independent spreading code is used.

By using CDMA spread spectrum technology, many users are able to use the same channel and gain access to the system without causing undue interference to each other. Latest news LoRa technology integrated in utility metering solution Four-in-one environmental sensor saves space and power MACOM debuts new ultra low phase noise amplifier Ericsson and Panasonic Avionics bringing connectivity to the skies Beeline chooses Broadpeak Solutions for TV Everywhere service.

Build More-Effective Smart Devices: The spreading code used in this example was only four bits long. CDMA is a form of spread spectrum transmission technology. The first part of the process is to generate the CDMA spread spectrum signal. This is multiplied with the spreading code to regenerate the original data. CDMA technology has been used in all the 3G cellular telecommunications systems in one form or another and has enabled significant improvements to be gained over previously technologies used in 2G systems, for example.

When transmitting a CDMA spread spectrum signal, the required data signal is multiplied with what is known as a spreading or chip code data stream.

In this way, CDMA is different to the previous schemes used to provide different cellular users with access to the radio network.

Broadcast technology Embedded Design principles Distribution Formulae. Had another code been used to regenerate the CDMA spread spectrum signal, then it would have resulted in a random sequence after de-spreading.

Mark Patrick Mouser Electronics Long-range low-power wireless network have the potential to bzsics the Internet of Agricultural Things The application of technology has always driven an increase in productivity, the two are inextricably linked because it is often the demand for higher productivity that provides cdmx motivation for achieving basisc breakthroughs; necessity is the mother of invention, after all.


Although as the number of users increases care has to be taken to ensure that interference levels do not rise to the extent that performance falls, it is still possible to provide access to a large number of different users and allow them access.

CDMA or Code Division Multiple Access fdma a form of access scheme that has been widely used within 3G cellular telecommunications systems as well as being used in a number of other technologies as well.

The same code must be sued within generation and decoding of the CDMA spread spectrum signal to enable the data to pass unchanged through the system.

CDMA spread spectrum basics

CDMA is based around the use of direct sequence spread spectrum techniques. For each data bit, the complete spreading code is used to multiple the fjletype, and in this way, for each data bits, the spread or expanded signal consists of four bits. The principle behind CDMA spread spectrum communications is relatively straightforward.

CDMA has been a particularly successful technology.

CDMA technology basics tutorial

basicz When this is done, then only the data with that was generated with the same spreading code is regenerated, all the other data that is generated from different spreading code streams is ignored. CDMA uses spread spectrum technology with the use of different codes to separate between different stations or users rather than different frequencies of time slots as in the case of previous access technologies. Latest news LoRa technology integrated in utility metering solution Four-in-one environmental sensor saves space and power MACOM debuts new ultra low phase noise amplifier Ericsson and Panasonic Avionics bringing connectivity to the skies Beeline chooses Broadpeak Solutions for TV Everywhere service.

Broadcast technology Embedded Design principles Distribution Formulae.