Basics of cdma

All the users can transmit at all times and at all frequencies. Because users are isolated by code, they can share the same carrier frequency, eliminating the frequency reuse problem encountered in other technologies.

Basics of cdma

Basics of cdma

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. 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.

In this way, CDMA is different to the previous schemes used to provide different cellular users with access to the radio network. The CDMA history can be directly linked back to the s when this form of transmission was first envisaged. As electronics technology improved, it started to 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, Basics of cdma furthermore it is difficult to jam.

With the revolution in cellular telecommunications that occurred in the s a then little know company named Qualcomm working on DSSS transmissions started to look at this as the basis for a cellular telecommunications multiple access scheme - CDMA - code division multiple access.

As a result this it was possible to start writing a specification for CDMA in This was only one cellular telecommunications system, although it was the first.

Its development lead on to the CDMA series of standards. It has a number of distinguishing features that are key to spread spectrum transmission technologies: Use of wide bandwidth: CDMA, like other spread spectrum technologies uses a wider bandwidth than would otherwise be needed for the transmission of the data.

This results in a number of advantages including an increased immunity to interference or jamming, and multiple user access. In order to achieve the increased bandwidth, the data is spread by use of a code which is independent of the data.

In order to receive the data, the receiver must have a knowledge of the spreading code, without this it is not possible to decipher the transmitted data, and this gives a measure of security. The use of the spreading codes which are independent for each user along with synchronous reception allow multiple users to access the same channel simultaneously.

One of the chief claims for CDMA is that it gives significant improvements in network capacity. Original expectations for some of the proponents of CDMA technology were for some very significant improvements: This in itself was a significant improvement.

Using CDMA it is possible for a terminal to communicate with two base stations at once. As a result, the old link only needs to be broken when the new one is firmly established. CDMA has been a particularly successful technology.

CDMA history

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.CDMA is interference limited multiple access system.

Because all users transmit on the same frequency, internal interference generated by the system is the most .

CDMA technology allows users to occupy the same frequency allocations in a given band at the same time and article give its working, types and applications. 11 CDMA Basics (1) z Each station is assigned a unique m-bit code (chip sequence) z To send bit 1, station sends chip sequence. z To send bit 0, station sends the complement. Code Division Multiplexing (CDMA): Instead of splitting the RF channel in to sub-channels or time slots. whole time slot is divided among different users so that at a time only one user is accessing the channel.

CDMA or Code Division Multiple Access is 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.

CDMA or Code Division Multiple Access is 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.

Basics of CDMA In Code Division Multiple Access (CDMA) systems the narrowband message signals are multiplied by spreading signals. All users in CDMA uses same carrier frequency and can transmit simultaneously.

CDMA Tutorial Introduction: This CDMA tutorial describes CDMA basics by explaining PN Sequence codes, Walsh codes,CDMA Physical layer for Base Station and Mobile Subscriber.

Basics of cdma

CDMA is the short form of Code Division Multiple Access. 3G UMTS / WCDMA Basics Tutorial - a tutorial, or overview of the basics of UMTS, Universal Mobile Telecommunications System, using WCDMA technology run under the auspices of 3GPP.

Basics Of Electronics and Communication Engineering: Basics of CDMA