what is Frequency hopping

Archived from groups: alt.cellular.gsm (More info?)

Hello,
Can anyone please kindly explain me what is called frequency hopping in
GSM.
Thank you
With warm regards,
DD
5 answers Last reply
More about what frequency hopping
  1. Archived from groups: alt.cellular.gsm (More info?)

    On 26 May 2005 22:22:28 -0700, "dd" <duttdharm@yahoo.com> wrote:

    >Hello,
    >Can anyone please kindly explain me what is called frequency hopping in
    >GSM.

    http://ccnga.uwaterloo.ca/~jscouria/GSM/gsmreport.html#4.6

    Frequency hopping
    The mobile station already has to be frequency agile, meaning it can
    move between a transmit, receive, and monitor time slot within one
    TDMA frame, which normally are on different frequencies. GSM makes use
    of this inherent frequency agility to implement slow frequency
    hopping, where the mobile and BTS transmit each TDMA frame on a
    different carrier frequency. The frequency hopping algorithm is
    broadcast on the Broadcast Control Channel. Since multipath fading is
    dependent on carrier frequency, slow frequency hopping helps alleviate
    the problem. In addition, co-channel interference is in effect
    randomized.


    --

    Regards

    John Riggs
  2. Archived from groups: alt.cellular.gsm (More info?)

    On 26 May 2005 22:22:28 -0700, "dd" <duttdharm@yahoo.com> wrote:

    >Hello,
    >Can anyone please kindly explain me what is called frequency hopping in
    >GSM.
    >Thank you
    >With warm regards,
    >DD
    GSM is not known for frequency hopping, the only time it happens is
    when your call is handed from one cell to another, the phone changes
    channels to a channel on the new BTS.

    By contreast CDMA is based upon splattering your call over 1.23 Mhz of
    bandwidth. The Shannon theorem tells us that spread spectrum operation
    is very hard to jam, and can operate with exceptionally poor S/N
    ratios.
  3. Archived from groups: alt.cellular.gsm (More info?)

    matt weber a présenté l'énoncé suivant :
    > GSM is not known for frequency hopping, the only time it happens is
    > when your call is handed from one cell to another, the phone changes
    > channels to a channel on the new BTS.

    bullshit

    --
    Christophe

    Couverture GSM Oléron 2003
    http://chantoine3.free.fr
  4. Archived from groups: alt.cellular.gsm (More info?)

    On Sat, 28 May 2005 10:39:43 +0200, "C Antoine"
    <chantoine99marreduspam@riendutoo.fr> wrote:

    >matt weber a présenté l'énoncé suivant :
    >> GSM is not known for frequency hopping, the only time it happens is
    >> when your call is handed from one cell to another, the phone changes
    >> channels to a channel on the new BTS.
    >
    >bullshit

    Hm..
    GSM broadcasts on a fixed channel that is 200Khz wide, that is time
    shared with up to 15 other calls (usuallh 7 other calls), using
    Gaussian Phase Shift Keying.

    Please tell me why you think transmitting with fixed bandwidth on a
    fixed channel is frequency hopping?
  5. Quote:
    Hm..
    GSM broadcasts on a fixed channel that is 200Khz wide, that is time
    shared with up to 15 other calls (usuallh 7 other calls), using
    Gaussian Phase Shift Keying.

    Please tell me why you think transmitting with fixed bandwidth on a
    fixed channel is frequency hopping?


    the usage of frequency hopping in GSM is optional; nevertheless its there. TDMA+freq hop is used to address the problem of channel fading.
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