what is the main difference between GSMand CDMA in telecommunication ?  

well, Traditional traffic in mobile cellular communication systems has been circuit switched voice data where a permanent link is set up between the communicating parties. In the future, it is envisaged that data communication will increasesubstantially and typically the requirements for a remote terminal to transmit data will not be continuous, but will be at irregular intervals. Consequently it is inefficient to have a continuous link set up between users. Instead a significantincrease in packet based data traffic is expected, where the transmitting remote terminal seeks to transmit the data in discrete data packets when necessary. An example of a packet based system is the General Packet Radio Service (GPRS) introduced forthe Global System for Mobile communication (GSM). Further details on data packet systems can be found in `Understanding data communications: from fundamentals to networking.
between the subscriber units and the base stations. This spectrum must be shared between all subscriber units simultaneously using the system.

One method of sharing this spectrum is by a technique known as Time Division Multiple Access (TDMA). In a TDMA communication system, the frequency spectrum is typically divided into a number of separate frequency channels or carriers and foreach of these carriers a plurality of subscriber units are served by being allocated distinct time intervals. Thus in the example of the IDMA communication system GSM, the frequency spectrum is divided into 200 kHz frequency channels each of which isdivided into eight separate time slots. A subscriber unit is allocated a specific time slot on a given frequency channel for communication with the serving base station. Further details of GSM can be found in `The GSM System for Mobile Communications.
source site: http://www.patentgenius.com/patent/ 7120437.html

Answered by Nidhi Singh at 6:19 PM on October 01, 2008

well, let's talk a little more about these two tecnologies:

CDMA: stands for Code Division Multiple Access. Both data and voice are separated from signals using codes and then transmited using a wide frequency range. Because of this, there are more space left for data transfer (this was one of the reasons why CDMA is the prefered technology for the 3G generation, which is broadband access and the use of big multimedia messages). 14% of the worldwide market goes to CDMA. For the 3G generation CDMA uses 1x EV-DO and EV-DV. It has a lot of users in Asia, specially in South Korea.
GSM: stands for Global System Mobile. Even though it is sold as "the latest technology" in several countries, this technology is older than CDMA (and also TDMA). But keep in mind that this doesn't mean that GSM is inferior or worse than CDMA. Roaming readiness and fraud prevention are two major advantages from this technology. GSM is the most used cell phone technology in the world, with 73% of the worldwide market. It has a very strong presence in Europe.

TDMA technology is the less used from the three main digital technologies (GSM, CDMA and TDMA) and we think it will gradually be replaced to CDMA or GSM. That's why the GSM vs CDMA war. At one corner, GSM operators say it is better "because it uses a SIM chip, it is the most used technology worldwide, it is more secure and it is more advanced". On the other corner, CDMA followers say it is better "because it is the 3G generation chosen technology and GSM will migrate to CDMA since CDMA is more advanced..."

But which one of these statements are correct? Acordingly to Nokia, "this discussion is not about technology anymore, but about market". We think this is the best way to describe the war between these two cell phone technologies.
source site: http://www.hardwaresecrets.com/arti cle/151

Answered by Romi at 4:48 PM on September 25, 2008

Home > Business > Special

CDMA Vs GSM - What's in it for you?

Thomas K Thomas | March 11, 2003

When Reliance India Mobile released its first ads, the deal looked like a steal. STD at 40 paise a minute, free handset, just Rs 500 a month, et al. Now that other mobile services companies are into price-cutting themselves, it's time for a rethink.

If you are among those who still cannot decide whether to go in for Reliance's Code Division Multiple Access (CDMA)-based 'limited mobility' phones or the 'full-fledged' cellular phone services provided by GSM (Global System for Mobile) operators, welcome to the club.

Which one is cheaper, which one better? While a number of issues still need clarity from the regulatory angle, let us take a close look at what Reliance is offering compared to a GSM phone.

First, the service: one of the limitations of a WLL (limited mobility) phone is that the user cannot go beyond a short distance charging area (SDCA) - which is roughly a radius of 25 km.

While Reliance has attempted to overcome the problem by offering multiple registrations, this still is not the equivalent of the roaming services offered by cellular operators.

For instance, if a subscriber in Delhi travels frequently to Mumbai, Reliance will register the subscriber in both the cities at an additional cost of Rs 20 to Rs 30.

So when the subscriber is in Mumbai, all calls landing on the user's Delhi phone number will be forwarded to a pre-allocated number in Mumbai. The user does not have to change the handset or put in a new SIM card for availing this facility.

However, when the user is in transit between the two cities, the phone does not work, unlike a GSM phone which offers roaming anywhere in the world.

Reliance is also offering text messaging services to cash in on the popularity of SMS. However, for the moment, any text message sent by a Reliance phone user can only be received by another Reliance user as GSM operators do not recognise this as a legal service. Even Tata Teleservices, another WLL operator, is awaiting clarity on this issue.

When it comes to data services, there is not much difference between GSM cellular operators and Reliance in terms of offerings.

Subscribers on either network will be able to send and receive e-mail, surf the Net, watch video clippings, send multimedia messages, and download games and ringtones.

The difference here is that while Reliance offers these services to all its subscribers, cellular operators offer such services only to those subscribers who have taken a General Packet Radio System (GPRS) connection - which requires a GPRS-enabled handset. The difference is also in the way the services are priced.

While Reliance is charging a regular talk-time rate of 40 paise a minute and a monthly fee of Rs 100 (under the club membership head), cellular subscribers have to pay a monthly fee ranging from Rs 250 to Rs 600, depending on the offerings, in addition to specified tariffs for each service.

For sending a multimedia message (MMS), cell users pay Rs 3 per MMS. For making voice calls, Reliance is charging 40 paise a minute. The finer print here is that this tariff is applicable only for calls made to another Reliance WLL subscriber.

Reliance is also offering STD calls at 40 paise a minute, but this too applies only to Reliance-to-Reliance calls.

If, for instance, you wish to call up a BSNL subscriber, you pay the standard Rs 4.80 per minute. The proposition looks strong only when you consider that Reliance is hoping to get one crore subscribers. But that may be some time away.

Initially at least, the WLL subscribers will end up making most of their calls outside the Reliance network and for this the user will have to pay an additional access charge, which ranges from 30 paise to 50 paise a minute, as specified by the Trai.

Answered by Madhurima at 6:30 PM on September 17, 2008

One of the basic things that differentiates GSM (based on TDMA) and CDMA is the way the carve up bandwidth.

Each bit of radio spectrum used by a handset has to be shared with other people in the area. It is more or less the same as multiplexing for normal data land lines.

The major difference between GSM/TDMA and CDMA is in the way they divide up those signals between multiple users.

GSM/TDMA uses a Time Division method. TDMA, in fact, stands for Time Division Multiple Access. Simply put, this means that each device on the local network is allocated a time slice where it "owns" the bandwidth, and it can send/receive its data.

So lets just pick a number and say there are 30 available time slices in a given cycle. Each phone would then get 1/30th of every cycle that it could send and receive data (aka, voice).

CDMA uses a different method, called Code Division Multiple Access. The specifics of how it breaks the cycle up are beyond me, but how it works out is that the phones only get a slice of the bandwidth cycle when they actually need one. So if you are not talking, and the other person is not talking, nothing is transmitted.

With GSM/TDMA, each phone is transmitting and receiving during its slices of the bandwidth cycle, whether it needs it or not.

Since most coversations are comprised largely of silence, the end result is that CDMA phones have to transmit less data. They don't have to send silence, like GSM/TDMA phones do.

This means a few things. More CDMA calls can be fit into a given amount of frequency spectrum (ie. it is more efficient for the network), less radiation is being created from the phone towards the user (you only get radiation when you are talking, basically), and battery power is conserved since the handset only transmits when it actually has something to send.

There are other differences, too, that I can't get into. For one, it is harder to implement a CDMA network. The tower placement is more difficult. Dealing with hills is more difficult than with GSM/TDMA. Things like that.

But in general, CDMA is vastly superior technology. Not surprising since Qualcomm's version of it (that which is used in CDMA and WCDMA phones) is newer technology, even if the basics were in use by the US military as far back as the 40s.

The important thing for me, though, is the SIM card. Had CDMA implemented the use of a SIM card (something it very easily could have done), then the North American market would be very different today, and there would be more CDMA networks in other countries. The SIM card allows people to easily switch phones, and that helps the market.

Answered by Shobhit at 7:05 PM on September 16, 2008

In cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). Cellular carriers including Sprint PCS, Cingular Wireless, Verizon and T-Mobile use one or the other. Understanding the difference between GSM and CDMA will allow you to choose a carrier that uses the preferable network technology for your needs.
The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.
Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.
Data Transfer Speed: With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies.
EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready.
GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required.
In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance.
Subscriber Identity Module (SIM) cards: In the United States only GSM phones use SIM cards. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention. The SIM itself is tied to the network, rather than the actual phone. Phones that are card-enabled can be used with any GSM carrier.
The CDMA equivalent, a R-UIM card, is only available in parts of Asia but remains on the horizon for the U.S. market. CDMA carriers in the U.S. require proprietary handsets that are linked to one carrier only and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one. The old phone becomes useless.

Answered by ayisha at 11:24 PM on September 15, 2008

In cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA).

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.

The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.

Answered by Shishir at 6:28 PM on September 15, 2008

CDMA is by a service providerm such as Verizon, Sprint, AT&T, and so fourth. GSM is by a third-party service, so if your a big tech guy, you can basically create your own service. (which is very expensive. Hope this helps an good luck!

CDMA:

code division multiple access is one of the method in encrypt a code.like FDMA.

GSM:

global system monitor is a system which used to send a data in wide range.

Answered by Nagendra at 1:58 PM on September 15, 2008

clearity of sound is more in cdma Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply "CDMA"), that use CDMA as their underlying channel access method.An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages.
The ubiquity of the GSM standard has been an advantage to both consumers (who benefit from the ability to roam and switch carriers without switching phones) and also to network operators (who can choose equipment from any of the many vendors implementing GSM[4]). GSM also pioneered a low-cost, to the network carrier, alternative to voice calls, the Short message service (SMS, also called "text messaging"), which is now supported on other mobile standards as well. Another advantage is that the standard includes one worldwide Emergency telephone number, 112. This makes it easier for international travellers to connect to emergency services without knowing the local emergency number.

Answered by ani at 1:47 PM on September 15, 2008

In cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). Cellular carriers including Sprint PCS, Cingular Wireless, Verizon and T-Mobile use one or the other. Understanding the difference between GSM and CDMA will allow you to choose a carrier that uses the preferable network technology for your needs.

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.

Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.

Answered by Sandeep at 1:02 PM on September 15, 2008

hi sekhar
CDMA and GSM are Radio technologies and mobile Phone is just an Antenna to recieve these Radio Signals. Since both the technologies work on different frequency range and has different modulation shemes therfore the mobile phones for both are different.

Apart from this 3G tehchnology which is combination of both GSM and CDMA (WCDMA) is compatible with both GSM and CDMA. So a 3G mobile can serve for both GSM and CDMA radio signals.

SIM (Subcriber Idendity Module) is consists of Credential for network authorization. Since Both GSM and CDMA technologies has different Authorization functions and parameters hence both SIMs are different.

Note: In CDMA technology SIM is often called as RUIM (Removable User Idendity Module)

CDMA uses Different Frequencies than GSM. CDMA also does not require a SIM card.

CDMA can hold more calls per channel on their towers, while GSM drops alot of calls. That is why people are always complaining about T-Mobile and At&t dropped calls. GSM is used internationally while CDMA is mostly used in the domestic United States. CDMA carriers are Verizon, Alltel, Sprint, Cricket....while GSM carriers here in the U.S. are T-Mobile and At&t.

http://doiop.com/pinkiphon e
http://doiop.com/cellware

hope this inf helps

Answered by LAKSHMI V at 12:42 PM on September 15, 2008