GSM Handoff Question

Discussion in 'OT Technology' started by YelloWRX, Nov 30, 2004.

  1. YelloWRX

    YelloWRX Sonic Yellow...Bitch!

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    I read somewhere that the Specs of CDMA require a soft handoff...That a signal is verified on an approaching tower before the present tower is left. I read that TDMA and GSM just "throw" the signal over to the next tower with no verification whether or not that tower can accept the call.

    Is this true? If so, why hasn't soft handoff been incorporated into the standard?
     
  2. skooter

    skooter Guest

    I have heard this to be true, although I could not find a verified source to reference, to my understanding a GSM signal sends two timeslots out to the towers for a better chance of getting through. I have never understood why GSM repeatedly is lax on security, because that doesn’t sound secure or efficient, extra timeslots could easily be engaged at other towers taking up slots that could be used for another subscriber.

    I had GSM service before and if this is true then it would explain the 10 second lag times I would experience most of the time while trying to make calls.
    GSM is a dead end standard, CDMA is the future.
     
  3. YelloWRX

    YelloWRX Sonic Yellow...Bitch!

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    Not sure what you mean about security...I thought they were both encrypted... I was just wondering if the hard handoff had something to do with more dropped calls on TMob/Cing
     
  4. DaveyD

    DaveyD Fuck Ohio State, son

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    If this is true, why is Cingular dumping all their advertsing money into the GSM network? Why is it that almost everywhere in the world uses GSM? Why is that some companies do not offer CDMA/TDMA services anymore? If you need info about cell phones, check out www.howardforums.com
     
  5. skooter

    skooter Guest

    I found this on another forum.

    Since "OFF-Time Slots" are efficiently handled in CDMA, the voice would be clear in reception if same bandwidth is allocated for bot GSM And CDMA. These "OFF-Time Slots" can be described as time when no-one on either line is speaking anything.
    ... For a part of conversation please think something like this..
    A: Please write my address.
    B: One Moment.
    ............silene, B is searching for a pen.....
    B: Yes please continue,
    A: abcdefthijk
    ..........(after some silence) .....
    B Continue....

    These silent slots can be used to increase sound clarity.


    GSM Mobile phones can be jammed, they use FDMA, and TDMA simultaneously, This FDMA (Frequency Division Multiple Access) can be found to find recent elevation in power level in a frequency band and that band can be Flooded with random digital high power signal to increase BitErrorRate beyond limit to remove phone off network. CDMA has got Code Division Multiple Access, using spread spectrum. So no specific frequency band can be received to decode the signal.


    Security.
    CDMA is secure. Since frequency Hops, and Code Division (The Code being the encryption Key ) The received signal can not be decrypted. This is not the case with GSM. A directional Antennae can find the probable bit pattern.


    SIM
    CDMA Mobile phones do not use SIM, because, the R-UIM used for authenticity has more space within to store. The encryption algorithms, etc.


    Recovering Bit Erros.
    CDMA Uses Viterbi code compression algorithm and hence has got an upper edge to recover Bit Error from Data. GSM only relies on CheckSum.
     
  6. grue

    grue New Member

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    CDMA = lose. No SIM card, no care.
     

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