CDMA Full Form
CDMA Full Form - Code Division Multiple Access
- Code Division Multiple Access may be a channel access method used by several radio communication technologies.
- It's a digital cellular technology and an example of multiple access. It's generally used for mobile communication.
- Multiple access means several transmitters can send information simultaneously over one channel.
- During this system, different CDMA codes are assigned to different users and therefore the user can access the entire bandwidth for the entire duration.
- It optimizes the use of accessible bandwidth because it transmits over the whole frequency range and doesn't limit the user's frequency range.
- CDMA allows several users to share a band of frequencies without undue interference between the users. It's used as an access method in many mobile standards.
- CDMA technology was developed in World War 2. It had been developed by English allies to protect their wireless transmissions from jamming.
- When the war ended, QUALCOMM patented this technology and made it commercially available. The primary CDMA system was launched in September 1995 in Hong Kong by Hutchison telephone co.
Features of CDMA
- At a defined time, it enables more users to speak and thus offers enhanced capacity for voice and digital communication.
- Many of the channels in CDMA use an entire spectrum.
- To reduce interference & noise and thereby increase the efficiency of the network, CDMA systems make use of power control.
- To protect its signals, CDMA encodes user transmissions into separate and special codes.
- The same frequency also can be used by all cells in CDMA systems.
- There is also no fixed limit to the amount of participants during a CDMA system, but performance degrades with an increment within the number of participants.
Applications of CDMA
- CDMA is used within the GPS (Global Positioning System)
- Several cell phone firms use this technology
- The UTMS 3G cell phone standard uses W-CDMA.
- CDMA was utilized in the OmniTRACS transportation satellite system.
Categories of CDMA
- Synchronous CDMA (orthogonal codes)
- Asynchronous CDMA (pseudorandom codes)
Difference between CDMA and GSM
CDMA vs GSM
|Technology||CDMA is based on spread-spectrum technology which makes
the optimum use of available bandwidth.
|GSM operates on the wedge spectrum. It uses both time division multiple access (TDMA) and frequency division multiple access (FDMA). TDMA provide multi-user access by cutting up the channel into different time slice and FDMA provides the multi-user access by separating the used frequency.|
|Security||CDMA is more secure than GSM.||GSM is less secure than CDMA.|
|Global reach||CDMA is used in USA and some part of Canada and japan.
CDMA is used only by 24% of the users worldwide.
|GSM is used over 80% of the world network in over 210 countries. GSM is used 76% of the users worldwide.|
|Data transfer rate||CDMA has faster data transfer as compared to GSM.||GSM has slower data transfer as compared to CDMA.|
|Radiation exposure||CDMA phones emits less radiation than GSM phones.||GSM phones emits continuous wave pulses and emits almost 28 times more radiation than CDMA phones.|