CDMA Network Explained

Mod · Joined: 12 May 2004 Posts: 855

A somewhat newer cellular technologies, many cellular companies are adopting the CDMA structure due to its range. Short for Code-Division Multiple Access, this is a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems that use TDMA, such as GSM, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum.

Individual conversations are encoded with a pseudo-random digital sequence. Many conversations are carried simultaneously by sending all communications in groups of bits mixed together, and tagging each group belonging to a specific communication with a different code. Each communication can therefore be reassembled in the correct order at the other end, using the unique codes attached to particular groups of bits.

CDMA is the most common and most recent digital cellular technology in North America.

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nokiamod · Joined: 21 Jan 2005 Posts: 105

I wouldn't say it's the MOST common.....anyways here's some more info:

CDMA employs analog-to-digital conversion in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern, so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. There are trillions of possible frequency-sequencing codes; this enhances privacy and makes cloning difficult.
The CDMA channel is nominally 1.23 MHz wide. CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another. The combination of digital and spread-spectrum modes supports several times as many signals per unit bandwidth as analog modes.

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Mod · Joined: 12 May 2004 Posts: 855

A bit of info: The first step in the evolution to 3G is cdma2000 1X, which improves packet data transmission capabilities and speeds in the network, and also boosts voice capacity. (Speed of up to 307 kbps.)

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Mod · Joined: 12 May 2004 Posts: 855

CDMA2000 1XEV-DO: (Evolution Data-Only). CDMA2000 1XEV represents the second step in the evolution of CDMA2000. Commercially launched in 2001, offers data speeds of up to 2.4 Mbps. CDMA2000 1XEV-DV: (Evolution Data-Voice).

CDMA2000 1XEV represents the next step in the evolution of CDMA2000. Approved by the International Telecommunications Union (ITU), a standards body based in Geneva, as a 3G technology to provide data and voice services together, with data rates of up to 3.09 Mbps.

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Arubiano · Joined: 24 Apr 2006 Posts: 1

Hi, im new to this and trying to find out more about CDMA,
Is CDMA in ur opinion better then GSM and is it true that it supports both data and voice unlike GSM...

As little as i know is that its a different format and therefore the current phones dont work on CDMA i think this will make it rather hard to compete with GSM since nowaydays almost all the phones are manufacered for the GSM network...

gio

Barry · Joined: 12 May 2004 Posts: 1473

[font "Verdana,Arial,Helvetica"][black][size 2]CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Therefore, hypothetically it should be better, but if it doesn't have enough network share (towers etc.) you could have them side by side with GSM phones and they won't be better. CDMA is a 'newar' technology but the biggest cell phone companies aroudn the world are GSM and the majority of the world providers are GSM.

You also can't easily switch over your SIM card in CDMA (there is no SIM card) therefore getting new unlocked phones is a no no. Phones need to be manufactured specifically for one network. THere are maybe 1 or 2 phones that switch between both (smartphone? maybe none...)
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Mod · Joined: 12 May 2004 Posts: 855

there are a few 'world' phones that do operate on both CDMA and GSM (not at the same time though)

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