query on 2 G and 3G communication systems.

[explorick]

According to me2G technologies are CDMA and GSM. It is given that GSM,d-AMPS,PDC are 2G communication systems in some manuals. Then where is CDMA in these communication systems
Is it true that 3GPP is an extension of GSM and WCDMA is an extension of CDMA then what is UMTS. Can anyone clarify regarding this.

 

[dchandresh]

according to my understanding the GSM which we are using right now is 2.5G & CDMA is also belongs to 2.5G.
But WCDMA and UMTS etc belongs to 3G, as 3G/4G basically provides an advantage of multimedia content delivery over these networks; is the main advantage.

 

[jjohn]

Code division multiple access (CDMA) is a form of multiplexing (not a modulation scheme) and a method of multiple access that does not divide up the channel by time (as in TDMA), or frequency (as in FDMA), but instead encodes data with a special code associated with each channel and uses the constructive interference properties of the special codes to perform the multiplexing. CDMA also refers to digital cellular telephony systems that make use of this multiple access scheme, such as those pioneered by Qualcomm, or W-CDMA.

CDMA is a military technology first used during World War II by English allies to foil German attempts at jamming transmissions. The allies decided to transmit over several frequencies, instead of one, making it difficult for the Germans to pick up the complete signal.

CDMA has since been used in many communications systems, including the Global Positioning System (GPS) and in the OmniTRACS satellite system for transportation logistics. The latter system was designed and built by Qualcomm, and became the seed which helped Qualcomm engineers to invent Soft Handoff and fast power control, the necessary technologies that made CDMA practical and efficient for terrestrial cellular communications.







The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 210 countries and territories [1] [2]. The ubiquity of the GSM standard makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are Digital call quality, which means that it is considered a second generation (2G) mobile phone system. This fact has also meant that data communication was built into the system from very early on. GSM is an open standard which is currently developed by the 3rd Generation Partnership Project (3GPP).
The GSM logo is used to identify compatible handsets and equipment
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The GSM logo is used to identify compatible handsets and equipment

From the point of view of the consumer, the key advantage of GSM systems has been higher digital voice quality and low cost alternatives to making calls such as text messaging. The advantage for network operators has been the ability to deploy equipment from different vendors because the open standard allows easy inter-operability. Like other cellular standards GSM allows network operators to offer roaming services which mean subscribers can use their phones all over the world.

As the GSM standard continued to develop, it retained backward compatibility with the original GSM phones; for example, packet data capabilities were added in the Release '97 version of the standard, by means of GPRS. Higher speed data transmission has also been introduced with EDGE in the

 

[explorick]

could u suggest me any papers or any brief manuals explaining these technologies mainly 3G.

Added after 2 minutes:

Also I have seen modules called as HSDPA Modem which is used for data communication i.e; they carry only data but not voice. Why these modules are supporting only data but not voice

 

[manojkrshukla]

see this material.