Welcome to Our WirelessAdvisor Community!

You are viewing our forums as a GUEST. Please join us so you can post and view all the pictures.
Registration is easy, fast and FREE!

Wireless Standards: What's the difference?

Discussion in 'GENERAL Wireless Discussion' started by Tralce, Aug 27, 2006.

  1. AG8000

    AG8000 Junior Member
    Junior Member

    Joined:
    Aug 4, 2006
    Messages:
    79
    Likes Received:
    0
    My Phone:
    T-Mobile MDA
    Wireless Provider(s):
    AT&T Mobility, Beyond Wireless GSM
    You need to get your facts straight. Where is evidence to back up this wonderful dream?
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  2. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
    GSM is a combination of Time and Frequency-Division Multiple Access (TDMA/FDMA). The FDMA part involves the division by frequency of the (maximum) 25 MHz bandwidth into 124 carrier frequencies spaced 200 kHz apart. Each of these carrier frequencies is then divided in time, using a TDMA scheme. The fundamental unit of time in this TDMA scheme is called a burst period and it lasts 15/26 ms (or approx. 0.577 ms). Eight burst periods are grouped into a TDMA frame (120/26 ms, or approx. 4.615 ms), which forms the basic unit for the definition of logical channels. One physical channel is one burst period per TDMA frame. Thus GSM allows eight simultaneous calls on the same radio frequency.


    HISTORY

    The GSM was originated in Europe (Global System for Mobile) in the year 1990 and gained world wide popularity because of its modern network features which are available to the individual mobile phone user. CDMA or code division multiple access was developed by Qualcomm Inc. and it became an international standard in 1995.

    TECHNICAL ISSUES

    As you know the mobile personal communication systems uses microwave frequencies above 800MHz for their transmission and reception purposes. They all are operating in some predefined or pre allocated frequency bands according to the international standards.

    For operating in these microwave frequencies they all need some access methods. And these methods are:

    1. Frequency division multiple access (FDMA)
    2.Time division multiple access (TDMA)
    3.Code division multiple access (CDMA)

    Thus CDMA is one access technology which cell phones uses to transmit and receive data. You can understand the meaning of FDMA, TDMA and CDMA eazily by just noting the word meaning for ezch letter. That is FDMA puts each call on a separate frequency and TDMA assigns each call a certain portion of time on a designated frequency for the above mentioned purpose. But CDMA gives a unique code to each call and spreads it over the available frequencies. All these are multiple access systems because more than one user can use the specified CELL ( not cell phone!) at a time.

    But GSM or Global System for Mobile uses the above mentioned TDMA ( Time Division Multiple Access ) for mobile communication purposes ! In other words GSM is a global standard based on TDMA and a very popular one in the entire Europe, Middle East, Asia and Africa and not an access code as CDMA but one global standard.( Remember it always....CDMA vs GSM is really misleading! it is CDMA vs TDMA..!)

    GSM operates in the 900 MHz band (890 MHz - 960 MHz) in Europe and Asia and in the 1900 MHz band in the United States. Besides these facts we must know the limitations and advantages of each systems in a brief way. All these facts are highly technical but i will try my best to write the details suite for all the mouthshut readers.

    First TDMA of GSM.
    The data transmission in TDMA is actually not continuous. It occurs in bursts. But the time between these bursts for a single mobile phone user is very very short, so that he never knows that the speech of the other person is discontinuous!

    As TDMA uses different time slots for transmission and reception your handset never need a duplexer. But it simply need a switch to transfer between transmission and reception sesseions!

    But the CDMA system has a soft capacity limit. That is increasing the number of users will decreases the system performance.( any comments Reliance users..?..!!).
    Channel data rates are very high in CDMA systems. But sel-jamming is a major problem.

    AND NOW SOME INTERESTING FACTS

    Above are the technical facts you must know. But as you are very familiar with GSM of BSNL, AIRTEL, ESCOTEL etc. and the CDMA of Relience i know you are also eager to know about some commonly misunderstood things.

    GSM is a widely spread standard and CDMA is a patented technology. That is you must pay a royalty for using CDMA! Also GSM covers the entire Europe , Asia except Korea, Africa and Middle East. So being a GSM user you have virtually an international roaming. You can eazily use a GSM phone in any of these countries while roaming.

    GSM users are almost 8 times in number than CDMA users worldwide. By being a GSM user you will be part of the largest mibile community.
    And coming to voice quality GSM is far better than CDMA, as i mentioned it earlier. CDMA base stations consumes less power than GSM and also covers a large distance. That is the cell size in CDMA is larger compared to GSM.

    In general i say both GSM and CDMA are frontier technologies and both have good and bad qualities. And in the case of mobile handsets the fact is that GSM handsets are very popular and many of the new facilties are readily available in GSM phones with lesser price. The reason is simple...nokia and motorola needs profit...and they will invest more in GSM because GSM has 8 times more users than CDMA.

    In the case of data rates also GSM is nowadays improving with their new GPRS. With GPRS it is expected that a data rate of about 171 kbps may be provided however on a shared basis between multiple users. GPRS enables an existing GSM system to communicate with any application or network that uses packet switching. GPRS thus allows subscribers to connect to the Internet to access applications as web browsing, mail and FTP.
     
  3. AG8000

    AG8000 Junior Member
    Junior Member

    Joined:
    Aug 4, 2006
    Messages:
    79
    Likes Received:
    0
    My Phone:
    T-Mobile MDA
    Wireless Provider(s):
    AT&T Mobility, Beyond Wireless GSM
    :loony: Yeah, a channel that's seven times as large as the one used for IS-136.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  4. hillbilly44

    hillbilly44 Senior Member
    Senior Member

    Joined:
    Mar 4, 2003
    Messages:
    713
    Likes Received:
    0
    AG;

    I guess you don't understand basic math then? The channel sizes are for TDMA & GSM are both 200Khz wide. As wireles said you can make 8 calls on GSM vs 4 on TDMA.That's why it more efficient:lmao:
     
  5. nKrypteD1

    nKrypteD1 Software Architect
    Senior Member

    Joined:
    Jun 21, 2006
    Messages:
    1,606
    Cell Tower Picture Gallery:
    4
    Likes Received:
    0
    Location:
    Atlanta, GA
    My Phone:
    Motorola Droid X
    Wireless Provider(s):
    Verizon
    ok let's see, 8 calls on 7 times the frequency, wouldn't that mean a 8 to 7 ratio that is far more effective? Again basic math.

    Personally I think there's really no room for this bickering between CDMA, TDMA here, the point of this post was to help understand the technological differences between the standards NOT PERSONAL OPINION. Both standards are fairly efficient and both have their pro's and con's. If you two wish to continue arguing please take it in private.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  6. walkguru

    walkguru Wireless Guru
    Senior Member

    Joined:
    Dec 26, 2005
    Messages:
    6,084
    Cell Tower Picture Gallery:
    28
    Likes Received:
    2
    Location:
    Oklahoma
    My Phone:
    iphone 3gs 32black
    Wireless Provider(s):
    cingular,family plan w/4 lines
    yep, sad but true, :browani:
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  7. hillbilly44

    hillbilly44 Senior Member
    Senior Member

    Joined:
    Mar 4, 2003
    Messages:
    713
    Likes Received:
    0
    nKrypteD1; I wasn't chosing the argument just trying to explan to AG the facts that he couldn't or wouldn't understand. :loony:
     
  8. nKrypteD1

    nKrypteD1 Software Architect
    Senior Member

    Joined:
    Jun 21, 2006
    Messages:
    1,606
    Cell Tower Picture Gallery:
    4
    Likes Received:
    0
    Location:
    Atlanta, GA
    My Phone:
    Motorola Droid X
    Wireless Provider(s):
    Verizon
    I'm not debating it, but the point remains the arguement in this thread is pointless, we all have our own personal preferences for whatever reason and I think we should put those aside to give valid information. I'm personally a large GSM fan myself and do mention that from time to time but it should come into play when giving out information, I constantly recommend alltel in areas where GSM penetration is weak as an example. I'm just asking that basically we accept each others differences here and don't let them come into play in areas where there really is no need. I appreciate your understanding in this and hope others follow suit.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  9. COtech

    COtech Bronze Senior Member
    Senior Member

    Joined:
    Sep 2, 2002
    Messages:
    1,043
    Likes Received:
    21
    Location:
    Memphis, TN
    My Phone:
    Sam. Galaxy SII Skyrocket
    Wireless Provider(s):
    AT&T Mobility
    IS-136 (TDMA) or D-AMPS, uses the same channel size as AMPS--30 kHz, and timeslices three calls in. You have the GSM numbers correct, 200 kHz and 8 calls.

    Since we need two-way audio, each end needs paired transmit and receive channels (reversed at each end). 25 MHz/2 = 12.5 MHz one way

    IS-136
    12.5 MHz / (30 kHz/channel) = 416 channels (and some guardband left over)
    That's 416 AMPS calls or 416 channels * (3 calls/channel) = 1248 TDMA calls.

    GSM
    12.5 MHz / (200 kHz/channel) = 62 channels (and some guardband left over)
    62 channels * (8 calls/channel) = 496 calls.

    Let the discussion resume, with numbers.

    COtech
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  10. jones

    jones Silver Senior Member
    Senior Member

    Joined:
    Nov 27, 2002
    Messages:
    3,424
    Likes Received:
    0
    China Mobile is the Biggest GSM Carrier.
    China Mobile added 48.6m customers over the past twelve months or almost 10% of the world total
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
    #40 jones, Oct 31, 2006
    Last edited: Oct 31, 2006
  11. gubak

    gubak Junior Member
    Junior Member

    Joined:
    Nov 15, 2006
    Messages:
    61
    Likes Received:
    0
  12. Bugwart

    Bugwart Bronze Senior Member
    Senior Member

    Joined:
    Feb 27, 2003
    Messages:
    952
    Likes Received:
    0
    Location:
    Eastern Pennsylvania
    My Phone:
    Samsung SCH i760,
    Wireless Provider(s):
    SKT, Verizon, China Mobile, EPlus
    wirles,
    The letters "GSM" come from Groupe Speciale Mobile. There was no "Global" in the original group that developed GSM.

     
  13. Bugwart

    Bugwart Bronze Senior Member
    Senior Member

    Joined:
    Feb 27, 2003
    Messages:
    952
    Likes Received:
    0
    Location:
    Eastern Pennsylvania
    My Phone:
    Samsung SCH i760,
    Wireless Provider(s):
    SKT, Verizon, China Mobile, EPlus
    China Mobile has been the world's largest cellular provider for quite a few years. Their largest competitor, Unicom, is the number 2 cellular provider not only in China, but also in the world.

    The point that I was making is that in many parts of Shanghai, China Mobile has bandwidth problems. My GSM phones all have 900 and 1800 MHz bands, thus this is not a frequency based problem, but rather a usage (over usage) problem.
     
  14. nKrypteD1

    nKrypteD1 Software Architect
    Senior Member

    Joined:
    Jun 21, 2006
    Messages:
    1,606
    Cell Tower Picture Gallery:
    4
    Likes Received:
    0
    Location:
    Atlanta, GA
    My Phone:
    Motorola Droid X
    Wireless Provider(s):
    Verizon
    True, Groupe Speciale Mobile translates (roughly) into Special Mobile Group, however, in US translation Global Standard for Mobile is adequate and true enough.


    Pure example of what problems all carriers face, client expansion at greater rates than capacity...

    Btw guys I'd like to throw another standard into this discussion ring because I think it's important to at least roughly mention, 802.11x. Ok the reason I bring this up, I've seen this question quite a few times and aside for the Security reasons the answer is roughly the same for the standards we're discussing.

    The question I've seen quite a bit, why do companies still hardwire their networks instead of using wifi (802.11x)? The answer is simple, there's a limited amount of bandwith available when you use wireless, anybody that has a 802.11g router is aware of this, 54Mbps, well what nobody usually notices is that everybody things it's 54Mbps per computer, it's not, the limit is for the entire spread of the wireless network. The frequency range (spectrum) is well defined and very limited, and that's how the 4 frequencies are all alike, irregardless. With GSM, CDMA, 802.11x, etc, there are limited frequency ranges, and those all have a specific capacity, even with all frequencies on a GSM network, 850, 900, 1800, 1900, the capacity per cell would still be limited, and furthermore you can't push cells too close to one another as it creates signal bleed, that's why microcell's have gained such popularity and things such as Tmobiles @home service are being pushed out quickly, by diversifying the way the phones operate, furthermore making them more "spotted/local" carriers greatly increase their networks capacity.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  15. jones

    jones Silver Senior Member
    Senior Member

    Joined:
    Nov 27, 2002
    Messages:
    3,424
    Likes Received:
    0
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  16. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
  17. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
    Exactly. It is physics. The channelized transmission is only capable of carrying a specific amount of information. The first way around this limit to increase bandwidth on wireless channels was the use of Frequency Hopping Spread Spectrum (FHSS). FHSS is one of two types of spread spectrum radio, the other being direct-sequence spread spectrum. FHSS is a transmission technology used in LAWN transmissions where the data signal is modulated with a narrowband carrier signal that "hops" in a random but predictable sequence from frequency to frequency as a function of time over a wide band of frequencies. The signal energy is spread in time domain rather than chopping each bit into small pieces in the frequency domain. This technique reduces interference because a signal from a narrowband system will only affect the spread spectrum signal if both are transmitting at the same frequency at the same time. If synchronized properly, a single logical channel is maintained.
     
  18. cpichrscp

    cpichrscp New Member

    Joined:
    Nov 19, 2006
    Messages:
    4
    Likes Received:
    0
  19. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
    cpich: Looks like an very detailed board you're starting there. Is it safe to assume by the content, you are a Fujistu employee?
     
  20. jones

    jones Silver Senior Member
    Senior Member

    Joined:
    Nov 27, 2002
    Messages:
    3,424
    Likes Received:
    0
    the discussion is the Difference bet GSM and CDMA
    and the Diffrence is:
    2.1 Billion GSM Users VS 300 Million CDMA Users .
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  21. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
    I submit that it is more related to the technological differences, not the business differences, but I digress.
     
  22. jones

    jones Silver Senior Member
    Senior Member

    Joined:
    Nov 27, 2002
    Messages:
    3,424
    Likes Received:
    0
    Technological Difference is also One,
    or Difference in Numbers like
    2.1 Billion (GSM Users) - 300 Million (CDMA Users) = 1.8 Billion
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  23. jones

    jones Silver Senior Member
    Senior Member

    Joined:
    Nov 27, 2002
    Messages:
    3,424
    Likes Received:
    0
    P.S.
    There are other Differences between GSM and CDMA:
    1. Diff. in Battery Life
    2. Diff. in Voice Quality
    3. Diff. in Coverage.
    4. Diff. in Phone Pricing
    And a whole Lot More,
    Not just Technological Difference.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  24. cpichrscp

    cpichrscp New Member

    Joined:
    Nov 19, 2006
    Messages:
    4
    Likes Received:
    0
    wirles: I m not a Fujitsu employee, but in wireless telecommunications industry.

     
  25. Bugwart

    Bugwart Bronze Senior Member
    Senior Member

    Joined:
    Feb 27, 2003
    Messages:
    952
    Likes Received:
    0
    Location:
    Eastern Pennsylvania
    My Phone:
    Samsung SCH i760,
    Wireless Provider(s):
    SKT, Verizon, China Mobile, EPlus
    "GSM" was not translated into "Global System for Mobile Communication" unless you are trying to tell us that "Marketing" is a new language.
     
  26. Bugwart

    Bugwart Bronze Senior Member
    Senior Member

    Joined:
    Feb 27, 2003
    Messages:
    952
    Likes Received:
    0
    Location:
    Eastern Pennsylvania
    My Phone:
    Samsung SCH i760,
    Wireless Provider(s):
    SKT, Verizon, China Mobile, EPlus
    We have answered all of these previously but it does no good to explain things to you.
     
  27. wirles

    wirles I'm baaaaaaaaaack
    Senior Member

    Joined:
    Jul 6, 2006
    Messages:
    723
    Cell Tower Picture Gallery:
    5
    Likes Received:
    1
    Location:
    In a SCIF
    My Phone:
    iPhone 4S
    Wireless Provider(s):
    All of the above
    Let's address your 'list' from the consumer perspective:

    1. Diff. in Battery Life - More dependent on individual handset features than the technology that it's based on.
    2. Diff. in Voice Quality - More dependent on the network design and coverage
    3. Diff. in Coverage. - See number 2
    4. Diff. in Phone Pricing - Not really a function of technology. More often a function of carrier business models. A RAZR for GSM is basically the same price as a RAZR for CDMA.

    Do you have any that truly are fundamental differences aside from the physical/electrical differences of the technologies from a scientific perspective that have been discussed ad nauseum already? How about you tell us the difference based on press releases. :cool:
     
  28. gubak

    gubak Junior Member
    Junior Member

    Joined:
    Nov 15, 2006
    Messages:
    61
    Likes Received:
    0
    Nice topic, thanks!
     
  29. strunke

    strunke .:|Always Covered|:.
    Senior Member

    Joined:
    May 28, 2005
    Messages:
    1,794
    Likes Received:
    6
    Location:
    BVR
    My Phone:
    Blackberry 8230, KRZR K1m
    Wireless Provider(s):
    Alltel, T-Mobile, Sprint, Centennial
    I'd like to say something else. Just because GSM has more users does not make it better then CDMA. That is like saying McDonald's taste better because more people eat there then Red Lobster. Okay, not quite, but you get my drift.

    And echoing wirles none of the list jones made has anything to do with what technology is being used. Coverage might be an issue but only in terms of how many carriers have each one, but technology wise it doesn't matter. If one is built out on the same frequency and on the same tower, it doesn't matter. They are the same.

    However here are a couple things that can be attributed to the technology....

    1. Call capacity and bandwidth
    2. Data speeds, correct me if I'm wrong.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  30. WirelessBeachBum

    WirelessBeachBum Soylent Green is People
    Senior Member

    Joined:
    Jul 10, 2002
    Messages:
    2,790
    Likes Received:
    16
    Location:
    Hilton Head Island, SC
    My Phone:
    Thunderbolt...still
    Wireless Provider(s):
    VZW
    My preference for cdma comes from working with cdma companies, and in my region cdma carriers dominate the landscape with generally better coverage.

    Hargray CDMA
    Alltel CDMA
    Verizon CDMA
    Sprint CDMA & IDEN
    Suncom Was GSM
    TMobile GSM
    Cingular GSM
    Southern Linc IDEN

    Suncom, TMobile, Cingular all have the spottiest coverage in my area, hence even if I was a GSM fanboy, I would still choose a CDMA carrier to have better coverage.

    Which is why most fans of one technology choose their service in the first place, coverage. (I don't care how many billions of people use a technology most wireless decisions are made on the local market level.)

    So the true difference in which one works best is personal preference and local market....if I lived in China I would not carry a CDMA phone...
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...

Share This Page

Copyright 1997-2022 Wireless Advisor™, LLC. All rights reserved. All registered and unregistered trademarks are the property of their respective holders.
WirelessAdvisor.com is not associated by ownership or membership with any cellular, PCS or wireless service provider companies and is not meant to be an endorsement of any company or service. Some links on these pages may be paid advertising or paid affiliate programs.

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice