Basics of cdma

Interface between different entities 3. It stores all related information of mobile subscribers that enter its coverage area, which enables MSC to set up incoming and outgoing calls. It is a static database.

Basics of cdma

It is also gaining a third name. This would be based upon the GSM core networks and the radio access technologies that they support i. It employs a 5 MHz channel bandwidth.

Using this bandwidth it has the capacity to carry over simultaneous voice calls, or it is able to carry data at speeds up to 2 Mbps in its original format.

The Technology Behind CDMA vs. GSM

However with the later enhancements of HSDPA and HSUPA described in other articles accessible from the cellular telecommunications menu page included in later releases of the standard the data transmission speeds have been increased to In this way the investment required is kept to a minimum.

The first modes to be employed are FDD modes where the uplink and downlink are on different frequencies. The spacing between them is MHz for Band 1 networks being currently used and rolled out. However the TDD mode where the uplink and downlink are split in time with the base stations and then the mobiles transmitting alternately on the same frequency is particularly suited to a variety of applications.

3G UMTS capabilities

Obviously where spectrum is limited and paired bands suitably spaced are not available. It also performs well where small cells are to be used. As a guard time is required between transmit and receive, this will be smaller when transit times are smaller as a result of the shorter distances being covered.

A further advantage arises from the fact that it is found that far more data is carried in the downlink as a result of internet surfing, video downloads and the like. This means that it is often better to allocate more capacity to the downlink. Where paired spectrum is used this is not possible.

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. In CDMA all sites use the same frequency. Soft handovers require less power. hence it is possible to make the connection to the new cell before leaving the current cell (Make before break). and then the connection to the new cell is made. the connection is made . cdma It is also known as spread spectrum because it takes the digitized version of an analog signal and spreads it out over a wider bandwidth at a lower power level.

However when a TDD system is used it is possible to alter the balance between downlink and uplink transmissions to accommodate this imbalance and thereby improve the efficiency. In this way TDD systems can be highly efficient when used in picocells for carrying Internet data.

The TDD systems have not been widely deployed, but this may occur more in the future.

CDMA Basics - DolceraWiki

Some of these key areas include: The UMTS radio interface provides the basic definition of the radio signal. 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 Read more about the code division multiple access.

Basics of cdma

The architecture for a UMTS network was designed to enable packet data to be carried over the network, whilst still enabling it to support circuit switched voice. All the usual functions enabling access toth e network, roaming and the like are also supported. Read more about the UMTS network architecture.

Within the CDMA signal format, a variety of forms of modulation are used. These are typically forms of phase shift keying. Read more about the modulation schemes.CDMA is interference limited multiple access system.

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

Basics Of Electronics and Communication Engineering: Basics of CDMA

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

CDMA is the short form of Code Division Multiple Access. It is the technique by which same frequency and time interval is used by Mobile subscribers/ Base Stations by way of unique digital codes. 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.

Basics of cdma

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. CDMA spread spectrum basics The key element of code division multiple access CDMA is its use of a form of transmission known as direct sequence spread spectrum, DSSS.

Direct sequence spread spectrum is a form of transmission that looks very similar to white noise over the bandwidth of the transmission.

Basics of Cdma Essay | Free Essays on Parson's College