Difference Between Gsm And Cdma

difference between GSM-CDMA Well, I am no expert, but I can probably fill in a few details. 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. Anyway, I hope that gives you a basic overview. __________________ -Michael (not Mike) MobileBurn.com Michael View Public Profile Visit Michael's homepage! Find all posts by Michael #3 04-14-2004, 11:06 AM

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Huh? You mean countries that use CDMA don't use SIM cards? Then what's the equivalent of the SIM card in a CDMA network? Another stupid question: Then why are there different frequencies (eg. 900, 1800, 1900) in a GSM network? Can a mobile operator support 2 frequencies? Lastly in CDMA, does it also have different frequencies? 3ple4 View Public Profile Find all posts by 3ple4 #4 04-14-2004, 12:45 PM

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Quote: Originally posted by 3ple4 Huh? You mean countries that use CDMA don't use SIM cards? Then what's the equivalent of the SIM card in a CDMA network? The phones have something called an ESN programmed into them. A serial number, if you will. The network assigns an ESN to an account. If you want to change phones, you call them and tell them the ESN of the new phone. Quote: Originally posted by 3ple4 Another stupid question: Then why are there different frequencies (eg. 900, 1800, 1900) in a GSM network? Can a mobile operator support 2 frequencies? Lastly in CDMA, does it also have different frequencies? What do you mean? There are different frequencies because different areas of the world use different frequencies for different things. Mobile operators can support multiple frequencies, but it is not in their best interest to do so. This ususally only happens after a merger. And yes, CDMA works on different frequencies. Sprint uses 1900Mhz, Verizon 800Mhz, for example. __________________ -Michael (not Mike) MobileBurn.com Michael View Public Profile Visit Michael's homepage! Find all posts by Michael #5 04-14-2004, 02:08 PM

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In South America CDMA is generally 1900MHz, elsewhere generally 800MHz. Brazil seems to have nothing but 1800MHz GSM. ALL US mobile services (CDMA, iDEN, GSM, analog, whatever) are 800 or 1900 or both becuase those are the only licensed bands. In Eastern Europe there are plans to use licenses for an old 450MHz band for CDMA networks. Theoretically any technology can be made to work on any band. But there are other pratical issues in terms of band choice, licensing and availability of compatible phones. iDEN phones are only made to work at 800MHz becuase of the licensing the largest operator: Nextel, was able to obtain. Even iDEN networks in Israel are 800MHz despite the general trend in Israel to license radio the way Europe licenses radio. (GSM in Israel is 900/1800.) I thought with WCDMA everyone in the world was going to be using 2100MHz to simplify things, but apparently ATTWS is planning 1900MHz WCDMA. That would mean that to build a 3G truly world phone with a SIM card, you'd need to include 5 bands (4GSM bands and 2 WCDMA bands). That's just a little silly. Anyone know if the FCC is licensing for WCDMA 2100? That would be good news.

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. Roaming: For the most part, both networks have fairly concentrated coverage in major cities and along major highways. GSM carriers, however, have roaming contracts with other GSM carriers, allowing wider coverage of more rural areas, generally speaking, often without roaming charges to the customer. CDMA networks may not cover rural areas as well as GSM carriers, and though they may contract with GSM cells for roaming in more rural areas, the charge to the customer will generally be significantly higher. International Roaming: If you need to make calls to other countries, a GSM carrier can offer international roaming, as GSM networks dominate the world market. If you travel to other countries you can even use your GSM cell phone abroad, providing it is a quadband phone (850/900/1800/1900 MHz). By purchasing a SIM card with minutes and a

local number in the country you are visiting, you can make calls against the card to save yourself international roaming charges from your carrier back home. CDMA phones that are not card-enabled do not have this capability, however there are several countries that use CDMA networks. Check with your CDMA provider for your specific requirements. According CDG.org, CDMA networks support over 270 million subscribers worldwide, while GSM.org tallies up their score at over 1 billion. As CDMA phones become R-UIM enabled and roaming contracts between networks improve, integration of the standards might eventually make differences all but transparent to the consumer. The chief GSM carriers in the United States are Cingular Wireless, recently merged with AT&T Wireless, and T-Mobile USA. Major CDMA carriers are Sprint PCS, Verizon and Virgin Mobile. There are also several smaller cellular companies on both networks. •

GSM is also known as Global System for Mobile Communications, or simply Global System for Mobile. A technology started development in 1985 by a French company formerly known as Groupe Spécial Mobile. It's main competetor is CDMA, currently in use by Bell Mobility, Telus Mobility and Mobility Canada carriers. Currently, only two main carriers in Canada are operating GSM networks. Microcell (Fido, Cityfone) and Rogers Wireless. Fido was the first carrier to start utilising this technology, followed by Rogers Wireless mainstream around 2001. Several companies in the United States have adopted GSM and it's spreading fast among AT&T Wireless, T-Mobile. GSM operates on 4 different frequencies worldwide. However, only two are which are used in Canada, which are GSM-850 and GSM-1900.GSM-850 and GSM-1900 which operate at 1.9Ghz. GSM calls are either based on data or voice. Voice calls use audio codecs called half-rate, full-rate and enhanced full-rate. Data calls can turn the cell phone into a modem operating at 9600 bps. An extended GSM feature is high speed circuit switched data, allowing the phone to transmit upto around 40 kbps. GPRS GPRS or General Packet Radio Service is an extended service of GSM Network adding the ability to surf the Internet on your phone at slightly higher speeds. GPRS Internet surfing is comparable to dial-up Internet service in it's speed, operating at around 4 to 5 Kilobytes per second. Surfing the net on your mobile isn't exactly cheap compared to residential Internet services. It is generally billed by how much data you transfer and it can get costly! We would not recommend the consumer use GPRS technology in place of a desktop computer with an Internet connection. It's just too expensive.

No real difference, just better coverage area because of type of phone. I guess what I am trying to find out, is one better or worse than the other and if there are any differences what are they." The coverage is a matter of terrain, number of towers, condition of the equipment and of course the handset plays a role too. There is NOTHING in the CDMA or GSM that dictates one will give you better than the other here for that issue. As I noted, if they implement it correctly, either will work for the end-users.

What is this "they are the same" dance you are doing. "If Implemented properly"... my a**. GSM phones are all super-sweet it seems, but hey, no towers! TDMA and CDMA are almost all over the country. I get CDMA service underneath the freakin Hudson river (seriously, if you don't know, the NJ Transit tunnels, and Holland and Lincoln Tunnels ge service, not sure about PATH haven't been there in awhile but it wasn't hot a year ago) I am not particularly a huge fan of Verizon, but at least when I get stranded on a skiing trip somewhere in Vermont I'll be able to pick up an AMPS signal. CDMA beats GSM anytime! I agree with you! I live in Charlotte but grew up in the lakes region of NH. I use to have Cingular(gsm). When I drove from Charlotte to NH, once I hit the VA state line, I'd have no service for over 200 miles. Service would come back around the West VA line, but was spotty. Once I got to my destination in NH, no service!! I switched to Alltell(CDMA) and I always have service! Occasionally I will lose service in remote areas for a few miles, but all and all I alwaus have good service. CDMA rules in the US! With GSM the cell sites know about your network With CDMA your handset has what is called a Primary Roaming List referred to as PRL, You the user are responsable for keeping this list up to date. With Verizon it is easy you dial *228 option 2 with Sprint PCS you have to call custormer service and request it (real PITA) I do mine every month when I pay the bill Other than that from the providers point of view CDMA cell sites are more expensive to build than GSM but they can handle more calls.

To be honest, I had AT&T Wireless and then moved to Verizon went Cingular ignored me. Verizon had better coverage than Cingular. Also, with 3g networks, Cingulat and TMobile are supossed to move to WCDMA (BASED ON CDMA). WHy doesn't everyone

move to Verizon or Sprint. CDMA has better coverage in the States. Altough when it comes to international, GSM takes it. Go with what suited you. I have a Unicel Phone and my I say that it is the best phone I have ever owned, and many people I know say the same. I live in Bennington Vermont and I have great coverage with the GSM, I know people that have Us cellular (CDMA) and get no service were I live, when I get FULL BARS. I dont believe it makes much difference if you have CDMA or GSM, I believe it only makes a difference if the company has the towers. I do know that you will get better service in Vermont with Verizon, if you compare it to Us cellular,but if you were to visit me I know I would have much better service with Unicel. Exactly. I'm not totally biased here, but I do work for Verizon Wireless. CDMA is more secure (i.e. output is coded in packets of data). It really just depends on the person who is using the service. I mean, some people LOVE T-Mobile. Personally, I had Verizon Wireless for years before I worked there. I switched to T-Mobile because my wife wanted a sidekick for her birthday. I got her one and myself one and was completely let down. I live in Phoenix, so it is a major metropolitan area, but the damn sidekicks' coverage sucks. Whenever she calls me from her kick the signal breaks up and it's horrible. When I started working there, I got us both the LG V. We now have kicks and V's and she even praises the V's coverage and has been preaching it to her friends. I will say that the functionality when it comes to Internet navigating is better with the kick, but slower. GSM is huge overseas, and they have a lot more features over there. The problem is that GSM in the U.S. is slightly different than the GSM the rest of the world uses. If you live in the United States, CDMA is the most secure and best for coverage. However, some locals will differ. YOu are almost correct about the countries that use CDMA. GSM is used here in the US and Europe mainly. China is split between the two. Australia ia mostly GSM. Japan is split between CDMA and their own digital network. CDMA is prodominate in S. America & India. GSM is a little older and doesn't have the potential for the future data applications. GSM speeds have just about peaked with the EDGE technology while CDMA speeds will reach DSL speeds in many markets this year. I am convinced the future is CDMA because of this. GSM is great for voice, but the future is in data and voice over IP(VOIP)applications and CDMA is far ahead in that arena. Often when a new member of the Brighthand forum asks for advice on which device to buy, one of the questions that trips them up has to do with cell phone technologies: which is better, and what these various acronyms and technologies even mean. CDMA and GSM are the names of competing cellular phone standards. They're about equal in the U.S. in terms of users, but overseas there's only GSM other than a few places like Japan, India, and Korea. Out of the four national carriers in the U.S., two -- Sprint and Verizon -- use CDMA, the other two--AT&T and T-Mobile -- use GSM.

The two biggest differences between these standards are international compatibility, and how the networks handle activating phones. Outside the U.S. and Canada, most GSM phones will still work, while almost all CDMA phones simply can't be used overseas. The only ones that can are those that also have a GSM radio. These are sold for people regularly traveling overseas on business, and are priced accordingly. CDMA phones are activated remotely, by the carrier, using the phone's serial number, known as the ESN. Since each carrier has a database of all the ESNs that are approved for its network, this lets most CDMA carriers refuse to activate phones not originally intended for their network. GSM phones are activated differently. Each account is associated with what's called a SIM card, or Subscriber Identity Module. This card, about the size of a fingertip and the thickness of a piece of paperboard, carries an encrypted version of all the information needed to identify your wireless account to the network. You slip it into the appropriate slot on a GSM phone (usually under the battery) and that phone is ready to use. Naturally, this means that you can use pretty much any compatible phone on a GSM network, with or without the carrier's permission. This is limited only by the phone supporting the right radio frequencies (850 and 1900 MHz for North America, 900 and 1800 MHz for overseas), and on the phone not being "locked" to a provider other than the one you're trying to use it with. Not only can you use a wider variety of phones with your service, it also allows you to take any GSM hardware and make it "your phone" instantly, including the ability to carry your contacts right on the SIM card. You could literally take your phone, smash it with a hammer, extract the SIM card, and with a backup phone in your glove compartment be back up and running in 30 seconds. Or you could carry a pre-paid SIM with you and pop it into your phone in case there was ever a time when you wanted to have phone service but not be reachable by your usual number. GSM's strength is in its flexibility. That's not to say CDMA providers don't have advantages. In the U.S., at least, Sprint and Verizon are well ahead of AT&T and T-Mobile on deploying high-speed Internet: both of the CDMA carriers have reasonably extensive wireless broadband footprints, while AT&T's is relatively small, and T-Mobile is still preparing to launch such a system. Thus, some users in the U.S. have to chose whether flexibility now is worth having to wait for the broadband coverage to catch up.

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GSM is also known as Global System for Mobile Communications, or simply Global System for Mobile. A technology started development in 1985 by a French company formerly known as Groupe Spécial Mobile. It's main competetor is CDMA, currently in use by Bell Mobility, Telus Mobility and Mobility Canada carriers.

Currently, only two main carriers in Canada are operating GSM networks. Microcell (Fido, Cityfone) and Rogers Wireless. Fido was the first carrier to start utilising this technology, followed by Rogers Wireless mainstream around 2001. Several companies in the United States have adopted GSM and it's spreading fast among AT&T Wireless, T-Mobile. GSM operates on 4 different frequencies worldwide. However, only two are which are used in Canada, which are GSM-850 and GSM-1900.GSM-850 and GSM-1900 which operate at 1.9Ghz. GSM calls are either based on data or voice. Voice calls use audio codecs called half-rate, full-rate and enhanced full-rate. Data calls can turn the cell phone into a modem operating at 9600 bps. An extended GSM feature is high speed circuit switched data, allowing the phone to transmit upto around 40 kbps. GPRS GPRS or General Packet Radio Service is an extended service of GSM Network adding the ability to surf the Internet on your phone at slightly higher speeds. GPRS Internet surfing is comparable to dial-up Internet service in it's speed, operating at around 4 to 5 Kilobytes per second. Surfing the net on your mobile isn't exactly cheap compared to residential Internet services. It is generally billed by how much data you transfer and it can get costly!

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We would not recommend the consumer use GPRS technology in place of a desktop computer with an Internet connection. It's just too expensive. The basic difference in GSM and CDMA technology is how they send communication signals to the base tower from a cell phone. GSM is well developed and widely accepted for mobile. Where CDMA is newer technology and users are reluctant to accept it. GSM is mainly working on 850, 900, 1800 and 1900 MHz. and good for voice and low data carried out on this compared to CDMA. CDMA is more advantageous for data with high speed. GSM is consuming more bandwidth and energy for same application to CDMA. GSM are compensating data speed with GPRS and EDGE and 3G technology. Still this technology is expensive and waiting for good public acceptance. Above are main points and that can be elaborated.

GSM Versus CDMA The Global Standards for Mobile is based on Time Divided Multiple Access and CDMA/WiLL is based on Code division. OK. What does this all mean for a common person? I put below my understanding and the results on seeing websites and opinions of my friends (including many MS brethren)

Superior Technology GSM and CDMA are apples and Oranges. Both offer the same quality and data access speed. Saying one is superior still gets debated (like the Microsoft or Java debates – never ending and never getting conclusive). The Packet Divided access in Japan (i-mode) is technologically the most superior with Voice, Data and Pictures travel in the same channel in different packets. Of course this makes sense when you have the infrastructure in place. Japanese have their own chain of Japanese Content Providers, Switch/Infrastructure Providers, and Handset Providers. So, they have become a hi-tech cocoon in their own way. Relevance of Technology Now, this is where CDMA has a clear advantage. They use the entire frequency spectrum and hence can have the broadcast happen at very high signal strength spread over bigger radius. For a city like chennai (a typical Indian city), the GSM grids requires something like 130 base stations to cover the city. The time slicing circuit is indeed costly and my friend working in BATATA tells me it costs 96 Lakhs for a base station. WiLL requires some 10 base stations in chennai as they beam all frequencies received by everyone (something similar to Ethernet broadcast in LAN where every computer listens to every packet and the intended recipient makes sense of message and acts upon it). Only the Handset, which incorporates the code, can decipher the signal and transmit too. WLL uses CDMA to loop to mobile phones. CDMA is a proprietary of Qualcomm and is in use where the Mobile service provider will have to serve bigger area like US. GSM is preferred where concentration of mobile phone providers across geographic area is more (More than 2 Service Providers in a 500 Km radius) and individual base stations are the best option – Europe. WiLL is invented by Ashok Jhunjhunwala a professor of IIT who is noted for his indianisation of technologies. Cost The GSM calls for heavy capital investment in the form of costly base stations with negligible operating cost. All the cost we pay them is their capital cost. WiLL have very less base stations, cheaper equipment and Shared costs on linking stations like optical fibres etc. This reduction in initial investment enables them to offer mobile outgoing at 1.20 per minute and incoming free (better position to negotiate calling-party-pays formula). In WiLL, the mobile handset cannot be reused when you switch suppliers. You are getting an unwritten commitment from the subscriber, which leads to further reduction of charges.

This tells us why Skycell went out of business because they cannot manage funds to counter reducing prices and how Reliance is pumping funds from RIL reserves to Infocomm and of course BSNL (Hee Hee unlimited tax payer’s funds J They have fixed line profits diverted) Since capital costs are manipulated in the era of diminishing interest rates, we will never get true picture. Data Transfer Negligible difference in data transfers rates between a GPRS (GSM) and CDMA. In India CDMA have not started data services yet. In fact, if you get a GPRS phone and activate 4 inward and one outward channel, the instrument is very fast in accessing WAP sites. Security Every software developer will vouch for this. More open a standard, more chances of bugs being pointed out and rectified. This applies for security. More open the security framework, less chances of a hole in it. GSM has this 800 page key encryption algos a secret. Basically there are 2 levels of encryption, one is for the frequency (so that any guy with a radio transmitter cannot detect the frequency which is set dynamically) and the other is for content (Even if you receive the frequency, you cannot demodulate to voice). The algos are noted as A3 and Kc respectively. It is POSSIBLE for someone to put fake base station (Employees of GSM provider???) and it is only a matter of time before a good hacker cracks these mathematical algos. Just like internet is hackable, GSM is clonable. This means somebody can then recreate the SIM card codes and can make and receive calls on your behalf. This prevents development of m-commerce in a big way. CDMA on the other hand says it plainly. I have the code. You can crack this provided you try ‘1 followed by 33 zeros’ times. Since it uses entire spectrum, base station snooping is not possible. I am not saying somebody can make over-the-air hack attack and clone your Airtel phone but GSM refused to give a declaration saying it CANNOT be done. This I would say is a fundamental flaw on the part of standards governing body. Bottom line Cut the jargons man. Tell me do I go for CDMA or GSM. Simple question but I ‘m afraid the answer may not be one. If you already have a GSM – don’t invest on new handset (Hope you are not gullible to read between the lines of reliance offer of free handset) The Plan of RPG/Airtel/Hutch allows you to have free receiving, mobile to mobile free and mobile to land line 2 Rs/min with 350 Rs/month. It’s a good offer

If you don’t already have a GSM, go for Cell One or Reliance. But note that GSM prices are expected to comedown next year as you are just paying capital cost. Sticking to Reliance (according to me) may not be prudent. But then you never know.