CDMA (2, 2.5, 2.75G)
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Emerging Technology » CDMA (2, 2.5, 2.75G)

 
Technology

CDMA (2, 2.5, 2.75G)

Full Name

Code Division Multiple Access

Description

Code division multiple access (CDMA) is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne, CDMA2000 (the 3G evolution of cdmaOne) and WCDMA (the 3G standard used by GSM carriers), which are often referred to as simply CDMA, and use CDMA as an underlying channel access method.

Origin/Facts

CDMA is a military technology, first used during World War II for jamming transmissions. The latter system was designed and built by Qualcomm, and became the seed which helped Qualcomm engineers to invent Sofxt Handoff and fast power control are the necessary technologies that made CDMA practical and efficient for terrestrial cellular communications.CDMA systems have been in commercial operation since 1995. The founders of QUALCOMM realized that CDMA technology could be used in commercial cellular communications to make even better use of the radio spectrum than other technologies. They developed the key advances that made CDMA suitable for cellular, then demonstrated a working prototype and began to license the technology to telecom equipment manufacturers. The first CDMA networks were commercially launched in 1995, and provided roughly 10 times more capacity than analog networks - far more than TDMA or GSM. Since then, CDMA has become the fastest-growing of all wireless technologies, with over 100 million subscribers worldwide. In addition to supporting more traffic, CDMA brings many other benefits to carriers and consumers, including better voice quality, broader coverage and stronger security.

Unit

Data Rates

CDMA IS-95 : 115.2 Kbps
CDMA 2000 1xRTT: 144 kbps (release 0),288 kbps (release A)
CDMA 2000 EV-DO(0): 2.4Mbps(DL),153kbps (UL)
CDMA 2000 EV-DO(A): 3.1Mbps(DL),1.8Mbps (UL)

Services Offered

Entertainment, Multimedia messaging services,Enterprise solutions,Push-to-Talk, SMS (Short Message Service), Web browsing, M-commerce, Location-based services, TV broadcasts video, audio downloads etc.

Range

Determined by many factors such as radiated power, power amplifier, type of antennas used and the height of their installation along with terrain. Approx 110 km .

Frequency/Channel

1900MHz, 800Mhz, 450MHz, 2100MHz

Advantages/Disadvantages

Advantages:
CDMA brings several major benefits over other similar technologies.
The transmission power is extremely small, so conversation is not only less radiation, but also longer battery life mobile phones.
The use of advanced soft-switching technology allows mobile phone is not GSM phones are dropped.
CDMA offers better call quality, almost no noise when making a call, in the case of large background noise, you can also get a better call quality
CDMA offers a high put-through rate. As military interference from CDMA systems, and the signal occupy the entire band, almost an ordinary narrow-band modulation efficiency of seven times, so for the same bandwidth, CDMA system is the GSM system capacity of 4 to 5 times the extent of its mesh-plug a significant decrease in Therefore, uptake rates are much higher.

Disadvanteges:
The code length has to be carefully selected. A large code length can induce delay or even cause interference.
Time synchronization is necessary.
Soft handoff increases use of radio resources and hence can reduce capacity.

Present/Future in SAMENA

The global users of CDMA based mobile phone services and fixed wireless services continue to grow.Code division multiple access (CDMA) technology faces an exciting future in Asia. Hard efforts of pro-CDMA vendors from Korea to North America, and the surprising success of CDMA-based 2.5G services in Japan, have created opportunities for the technology in both mature, increasingly data-centric markets and underdeveloped basic voice markets. The success of CDMA2000 projects in Asia will depend on favorable regulation, cheap handsets and the ability of CDMA operators to differentiate themselves from competitors.

Worldwide Customers

626 million

 
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