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CDMA Versus TDMA

Discussion in 'GENERAL Wireless Discussion' started by Waycole, Feb 28, 2002.

  1. Waycole

    Waycole New Member

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    CDMA or TDMA, Which is better and is the REALLY that much difference between the two?
     
  2. KevinJames

    KevinJames WA's 1st retired mod
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  3. Malial

    Malial Senior Member
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    << CDMA or TDMA, Which is better and is the REALLY that much difference between the two? >>



    Can open.....Worms everywhere[​IMG]

    This is the never ending debate...

    Here is a good article about the differences: CDMA vs. TDMA

    It's really a personal opinion...and it always comes down to who has the best coverage in the areas that you will be using your phone.
     
  4. BillRadio

    BillRadio Wireless Consultant
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    I have an opinion of CDMA vs TDMA, but there are two bigger players whose opinion should speak louder about TDMA technology. Both Cingular and AT&T Wireless, the two largest TDMA carriers, are converting to GSM technology. What does THAT say about TDMA?

    -Bill
     
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  5. Malial

    Malial Senior Member
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    << I have an opinion of CDMA vs TDMA, but there are two bigger players whose opinion should speak louder about TDMA technology. Both Cingular and AT&T Wireless, the two largest TDMA carriers, are converting to GSM technology. What does THAT say about TDMA?

    -Bill
    >>



    well...technically GSM is still TDMA technology, just taken to the next step.

    Besides that....the 3G solutions, WCDMA and CDMA 2000 are both based on CDMA...what does that say about TDMA?

    [​IMG]
     
  6. KevinJames

    KevinJames WA's 1st retired mod
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    Now, now girls. Lets not get into a cat fight. Yes, we all know that technology grows. I'm already reading articles about 4G and 5G. So what does THAT say about technology? It will never be perfect. It will always grow.
     
  7. Kenny

    Kenny Senior Member
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    I don't think there's much argument here...CDMA is a more advanced technology than the older TDMA technology -- handles more call volume and has better voice clarity. Now although GSM is a form of TDMA, it's nevertheless a more advanced implementation of TDMA and offers a better CODEC and thus offers better voice clarity. AT&T GSM users I have heard from in Chicago noticed that the voice clarity is much better over it's TDMA network.

    But both TDMA and GSM are also disadvantaged against CDMA when it comes to data/internet transmission because they are circuit-switched technologies versus the packet-based technology of CDMA. If you are knowledgeable about computers then you'd know what I'm talking about.

    Now, AT&T and Cingular's conversion/overlay of GSM is only a stepping stone to the eventual W-CDMA (Wideband spread sprectrum air interface). The first step in offering data/internet services for current or newly implemented GSM carriers is via GPRS (General Packet Radio Service)...an implementation that'll offer packet-based data transmission.

    But to offer the best wireless services takes more than just picking the best technology. There are other factors you need to consider such as the quantity and distribution of cell sites/towers to handle the call volume appropriately.
     
  8. MAC

    MAC New Member

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    And just where does one go to get that information (distribution/location of cell towers) when comparing service providers?
     
  9. Kenny

    Kenny Senior Member
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    Sorry I need to clarify something here which presents a problem to many cellphone users...quantity and distribution of cell sites/towers play a major role in the quality of cellphone reception but unfortunately I don't think you can get a hold of all that detailed information from the carriers. They are constantly upgrading and adding cell sites and so it's hard to keep up-to-date. There was an article I posted somewhere here in this forum whereby it focused on this very topic. Carriers aren't about to release detailed information they have on "dead spots."

    So I guess when I mentioned about "considering the quantity and distribution of cell sites/towers" I was speaking in the context of an engineering standpoint when comparing the different air interface technologies and which ultimately affects the quality of service and volume of calls that can be handled.
     
  10. Guest

    Guest Guest

    GSM has the best voice quality and security due to the SIM card (a tiny card microchip inside the mobile phone) which other competing standard don't have. [​IMG][​IMG]
     
  11. UWS

    UWS New Member

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    &lt;&lt;GSM has the best voice quality and security due to the SIM card (a tiny card microchip inside the mobile phone) which other competing standard don't have.&gt;&gt;Text

    I agree on GSM has the best voice quuality.. only if the phone has good signal. And about the security due to the SIM card. what if you have nice fancy tri-band world phone you purchase couple days ago.. If you lost the phone.. whoever also has the GSM service.. =) oh well... all he gotta do is take the SIM card out and put his card in the phone.. All other service provider has phone lock down system. which if you lost the phone or anything happends to it they will lock the ESN so that no one else can use the phone...
     
  12. CDANMA

    CDANMA Junior Member
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    Well I think the TDMA vs. CDMA is pretty cut and dry, but there ara alot of other thing to take into play with voice quality.

    Either in TDMA,CDMA and GSM.I will have to agree with Kenny on the fact of cell tower placement and coverage % make a really big deal. I will also tell you that even if you have towers every 1/2 mile in the city that doesn't mean that will be the better network. Optimization of there network is key.....

    In the CDMA world you have to worry about frame error rates to have great call quality. Also VoCoder rates make a big difference. There are three major Vocoder rate in CDMA 13k, 8k and EVRC. EVRC being the best overall quality process.TDMA also has it's problems,but much more simple than CDMA.

    Remember TDMA is based in AMPS and CDMA on Packet switching,so which do you really thing is better???
     
  13. Guest

    Guest Guest

    CDANMA,

    Huh!?
    Your comments make NO sense -- and the last one is simply flat out WRONG!

    AMPS is an analog FREQUENCY separated technology. TDMA is a digital TIME separated technology. They have nothing to do with each other. You can use TDMA over any transport -- ie PCS or even baseband.

    And I have no idea what CDMA and packet switching have to do with each other. CDMA is an air interface/transmission technology. Packet switching has to do with how the message is carried through the telephone network.
     
  14. Apoc

    Apoc Senior Member
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    I say depends on what market you live in!!
     
  15. CDANMA

    CDANMA Junior Member
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    Anonymous,
    I'm not going to try to argue with you,but I will explain how TDMA works in the real world.....
    I agree that TDMA is a Time based technology,never said it wasn't.
    But a TDMA cell site was derived from AMPS technology.
    1. Amps has Control channels ,TDMA has digital control channels to set the call up.
    2. AMPS uses different Freq. between cells ,same way with TDMA
    3.TDMA actually uses the same radios in the cellsite that AMPS use
    TDMA took an analog radio and found a way to put multiple digital call in the same radio(using time slots to do it)


    CDMA now......
    1. Each CDMA carrier (freq.) i.e. F1 or F2 and so on use one freq per carrier. A Band F1 primary (283), B Band primary (384) (Not sure about PCS!!!)
    2. FER (frame error rate) in CDMA FER is important to keep it low because you loss data between the site and the phone,causing drops or even what we call digital garbage...
    3.Vocoder rate do many things and one of them is improve voice quaility(EVRC in basic terms is a variable data rate and when you are not talking it inserts blank air in its place,that also increases call volume of the cell.)
    4.Also I find it funny that Lucent calls the trunk group between the cell and the MTSO a Packet Pipe
    CDMA(I will give you in loose terms) is based on packet data.

    One other thing, I have worked on Nortel MTX switch,Lucent 5ESS switch and both AMPS and CDMA cell sites, so I have the real world outlook in this.
    So I don't concern myself with King's thery in CDMA or IS-136 protocol in TDMA. I look at it from the equipment side(cellsite,Switch) of it......
     
  16. ILUVSOCAL

    ILUVSOCAL Banned
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    I personally have used/do use TDMA, GSM, and CMDA and when the connection is good and I have a good phone, I cannot tell the difference between them. Even under less that perfect circumstances, I still find it hard to tell the difference. The only difference I have noticed is that CDMA seems to warble and drop words sometimes when I am moving in a car. I really could care less who is better than the other, as long as they work well, and sound good. That, after all, is what's important. Now I have to say that in my opinion, GSM is the most full featured and secure of the three, CDMA is the most efficient, and TDMA is the most field proven. Now about TDMA being old and at the end of it's usefullness, that is probably true, but that doesn't meant it's suddenly no good. Look at the railroads, who used Steam well into the diesel age, and airlines who used props extensively into the jet age. It's called phasing out. I look forward to the day of 3G, when we will have one good digital technology that will work worldwide, regardless of where you're at. It will be secure, sound great, and have features such as video on demand and video conferencing standard. What technolgy will that be? Who knows, but it will come, and it will take the best from the past and make the future better [​IMG]
     
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  17. Guest

    Guest Guest

    GSM means you can send a Text Message to Bangladesh where most people can't afford to buy a PC and calling them is expensive. Also you can send it outside the States.

    CDMA you can't send a Text Message to 3rd world countries or outside the USA it will NOT work. You can only send Text Messages in the USA since the cell phones don't have an EMAIL address.
    [​IMG]
     
  18. Guest

    Guest Guest

    GSM means you can send a Text Message to Bangladesh where most people can't afford to buy a PC and calling them is expensive. Also you can send it outside the States.

    CDMA you can't send a Text Message to 3rd world countries or outside the USA it will NOT work. You can only send Text Messages in the USA since the cell phones outside the USA don't have an EMAIL address.
    [​IMG]
     
  19. Guest

    Guest Guest

    If you lost the phone.. whoever also has the GSM service.. =) oh well... all he gotta do is take the SIM card out and put his card in the phone.. All other service provider has phone lock down system. which if you lost the phone or anything happends to it they will lock the ESN so that no one else can use the phone...

    This is true, in fact this triggered phone theft in Europe. But the manufacturers did something on GSM phones that if you are using a stolen phone the carrier will know.
     
  20. theyallstink

    theyallstink Junior Member
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    CDMA vs TDMA vs GSM

    First off, the best service is the one that has good signal strength where you'll be using it. Selecting a carrier based on technology and then finding out you have no service at home is a bad decision. One point where CDMA should excel is its ability to send/receive calls in weak signal locations, slightly better than GSM/TDMA. This might not be the case in all situations. GSM is a good choice if travelling to Europe or many other regions of the world. GSM is not the best choice today for travelling in America. In another 12-18 months that might change.

    Assuming all things were equal, I would select CDMA. IMO, the voice quality is the best if using a newer phone, though many GSM users would argue that. It really depends on your carrier, some CDMA systems will sound better than others and some areas will be better. This is due to setup of towers and how many users they provision for the towers, etc... This is all adjustable by the carrier. With GSM, some carriers employ FDMA as well (frequency division) and some don't. Also, I've found that GSM warbles in weak signal areas, CDMA stays relatively stable up until the point its close to dropping the call.

    CDMA also has soft handoffs so no more hearing a click or pause (or dropped call) when switching between towers.

    I've had little reason to complain about the voice quality on Verizon or Sprint. For the most part it sounds like a land line. Theoretcially CDMA carriers should reach true 3G data speeds before GSM carriers. CDMA has a proven technology path to faster data speeds. One such network already runs in Japan. GSM speeds above 144K are iffy as of today. GSM is relying on a vaporware technology called EDGE that might or might not work as planned. In the end all carriers worldwide will be on W-CDMA in about 5 years.
     
  21. IdiOTeQnoLogY

    IdiOTeQnoLogY Bronze Senior Member
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    nice summary of all the three main techs.

    wcdma is havin probs right now though it is a less proven tech than cdma2000 so they should be ironed out and working soon.

    the article on wcdma problems is in this forum just a slightly earlier thread bout 10 down [​IMG]
     
  22. bobolito

    bobolito Diamond Senior Member
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