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- 09-12-2006, 01:20 AM #1Guest
I want to know how a gsm mobile gets connected to its network for the
first time when it powered up for the first time given there are six
other gsm operators working. Can anyone help me out?
› See More: GSM Booting sequence
- 09-12-2006, 01:52 AM #2Jonathan WilsonGuest
Re: GSM Booting sequence
[email protected] wrote:
> I want to know how a gsm mobile gets connected to its network for the
> first time when it powered up for the first time given there are six
> other gsm operators working. Can anyone help me out?
The SIM card contains unique information identifying the specific operator
which the phone uses to connect to that operators towers.
- 09-12-2006, 04:51 AM #3k00LGuest
Re: GSM Booting sequence
thanks but on which channel the mobile send the information
Jonathan Wilson wrote:
> [email protected] wrote:
> > I want to know how a gsm mobile gets connected to its network for the
> > first time when it powered up for the first time given there are six
> > other gsm operators working. Can anyone help me out?
> The SIM card contains unique information identifying the specific operator
> which the phone uses to connect to that operators towers.
- 09-12-2006, 06:01 AM #4Jeremy QuirkeGuest
Re: GSM Booting sequence
"k00L" <[email protected]> wrote in message
news:[email protected]...
> thanks but on which channel the mobile send the information
> Jonathan Wilson wrote:
>> [email protected] wrote:
>> > I want to know how a gsm mobile gets connected to its network for the
>> > first time when it powered up for the first time given there are six
>> > other gsm operators working. Can anyone help me out?
>> The SIM card contains unique information identifying the specific
>> operator
>> which the phone uses to connect to that operators towers.
>
I'd tell you to do your own homework but with the state of Australian
universities these days no doubt you'll just plagiarise it from somewhere
else. And others here may be interested.
GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
down to is that the SIM keeps a 'cache' of the last known location area and
allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
The SIM also has a stored preferred and forbidden PLMN list of network codes
to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
With a smartcard reader you can also inspect the contents of the EFBCCH file
to see what ARFCN channel numbers (frequencies) your network uses.
Basically, when your phone is turned on, all of these cached parameters are
used in some way to optimize the search for the home network. If this
network can't be found, then the phone tries other networks until it
successfully is able to IMSI-attach ("login") to one of them. This is how
roaming works.
As for which channels the mobile uses for 'connecting' to the GSM network
(which is not really the correct term, as at most a location update is
performed and then the mobile returns to idle mode) - there are several
used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
technically involved. However, the two main channels of interest are the
BCCH where all sorts of information about the network is constantly
broadcast over and over again (allowing mobiles to decide which cells to
camp on, whose network it is, etc, etc) - this is how the MS identifies a
candidate cell. Then, when it wishes to IMSI-attach/location update, it will
do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
for most non-voice/data connections (mobility functions, SMS, setting up a
voice call, etc).
- 09-12-2006, 06:03 PM #5Nole BoadayGuest
Re: GSM Booting sequence
Jeremy Quirke wrote:
> "k00L" <[email protected]> wrote in message
> news:[email protected]...
>> thanks but on which channel the mobile send the information
>> Jonathan Wilson wrote:
>>> [email protected] wrote:
>>>> I want to know how a gsm mobile gets connected to its network for the
>>>> first time when it powered up for the first time given there are six
>>>> other gsm operators working. Can anyone help me out?
>>> The SIM card contains unique information identifying the specific
>>> operator
>>> which the phone uses to connect to that operators towers.
>
> I'd tell you to do your own homework but with the state of Australian
> universities these days no doubt you'll just plagiarise it from somewhere
> else. And others here may be interested.
>
> GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
> down to is that the SIM keeps a 'cache' of the last known location area and
> allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
> The SIM also has a stored preferred and forbidden PLMN list of network codes
> to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
> the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
> With a smartcard reader you can also inspect the contents of the EFBCCH file
> to see what ARFCN channel numbers (frequencies) your network uses.
>
> Basically, when your phone is turned on, all of these cached parameters are
> used in some way to optimize the search for the home network. If this
> network can't be found, then the phone tries other networks until it
> successfully is able to IMSI-attach ("login") to one of them. This is how
> roaming works.
>
> As for which channels the mobile uses for 'connecting' to the GSM network
> (which is not really the correct term, as at most a location update is
> performed and then the mobile returns to idle mode) - there are several
> used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
> technically involved. However, the two main channels of interest are the
> BCCH where all sorts of information about the network is constantly
> broadcast over and over again (allowing mobiles to decide which cells to
> camp on, whose network it is, etc, etc) - this is how the MS identifies a
> candidate cell. Then, when it wishes to IMSI-attach/location update, it will
> do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
> for most non-voice/data connections (mobility functions, SMS, setting up a
> voice call, etc).
>
I'm curious as well on this topic. So there's a specific
frequency/channel that is shared between all mobile providers around the
world in which they continually broadcast their network details?
I’ve always been curious as to how you can take your GSM phone to a
different country, with different networks running of different
frequencies (well, deviations from ~900Mhz say), and still pick one of
them up.
- 09-12-2006, 07:58 PM #6Jeremy QuirkeGuest
Re: GSM Booting sequence
Nole Boaday wrote:
> Jeremy Quirke wrote:
> > "k00L" <[email protected]> wrote in message
> > news:[email protected]...
> >> thanks but on which channel the mobile send the information
> >> Jonathan Wilson wrote:
> >>> [email protected] wrote:
> >>>> I want to know how a gsm mobile gets connected to its network for the
> >>>> first time when it powered up for the first time given there are six
> >>>> other gsm operators working. Can anyone help me out?
> >>> The SIM card contains unique information identifying the specific
> >>> operator
> >>> which the phone uses to connect to that operators towers.
> >
> > I'd tell you to do your own homework but with the state of Australian
> > universities these days no doubt you'll just plagiarise it from somewhere
> > else. And others here may be interested.
> >
> > GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
> > down to is that the SIM keeps a 'cache' of the last known location area and
> > allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
> > The SIM also has a stored preferred and forbidden PLMN list of network codes
> > to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
> > the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
> > With a smartcard reader you can also inspect the contents of the EFBCCH file
> > to see what ARFCN channel numbers (frequencies) your network uses.
> >
> > Basically, when your phone is turned on, all of these cached parameters are
> > used in some way to optimize the search for the home network. If this
> > network can't be found, then the phone tries other networks until it
> > successfully is able to IMSI-attach ("login") to one of them. This is how
> > roaming works.
> >
> > As for which channels the mobile uses for 'connecting' to the GSM network
> > (which is not really the correct term, as at most a location update is
> > performed and then the mobile returns to idle mode) - there are several
> > used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
> > technically involved. However, the two main channels of interest are the
> > BCCH where all sorts of information about the network is constantly
> > broadcast over and over again (allowing mobiles to decide which cells to
> > camp on, whose network it is, etc, etc) - this is how the MS identifies a
> > candidate cell. Then, when it wishes to IMSI-attach/location update, it will
> > do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
> > for most non-voice/data connections (mobility functions, SMS, setting up a
> > voice call, etc).
> >
>
> I'm curious as well on this topic. So there's a specific
> frequency/channel that is shared between all mobile providers around the
> world in which they continually broadcast their network details?
>
Not quite. Each base station (well cell really, since a base station
has multiple cells usually) has a dedicated timeslot on a fixed (i.e.
non hopping) frequency which constantly broadcasts parameters about the
network and that particular cell, over and over.
Thus the mobile has to scan the bands constantly looking for other
cells to use even if it has found a cell, or to find an initial cell.
This means searching all channels of the MSes supported bands (900,
1800, 1900, etc).
As mentioned before however some of the broadcast (known as BCCH)
information contains hints about channels and bands to search for this
network, to speed up search. And the network may have policies on what
frequencies can carry a BCCH, to further speed up search (or for other
reasons). For example, Optus in Australia (at least a while back)
generally used every other physical channel number in their 900
spectrum (i.e. 41, 43, ..., 79, 81).
> I've always been curious as to how you can take your GSM phone to a
> different country, with different networks running of different
> frequencies (well, deviations from ~900Mhz say), and still pick one of
> them up.
Again, normally the MS will keep trying until a network accepts its
IMSI-attach request.
- 09-13-2006, 04:08 AM #7FreakyAyeGuest
Re: GSM Booting sequence
thanks for taht info, where can we read more?
--
FreakyAye
- 09-13-2006, 04:08 AM #8FreakyAyeGuest
Re: GSM Booting sequence
thanks for taht info, where can we read more?
--
FreakyAye
- 09-13-2006, 08:23 AM #9Jeremy QuirkeGuest
Re: GSM Booting sequence
"FreakyAye" <[email protected]> wrote in message
news:[email protected]...
>
> thanks for taht info, where can we read more?
>
>
> --
> FreakyAye
"GSM 03.22, 04.08 and 05.02 are the best places to start."
More generally start with the 02 series documents and work up, as you get
higher it generally gets more complex and increases the "depth" of
information.
03 is a general overview of the system
04 is protocol & procedures details
05 is radio layer stuff
06 is codecs etc
And you get the idea =)
- 09-13-2006, 08:23 AM #10Jeremy QuirkeGuest
Re: GSM Booting sequence
"FreakyAye" <[email protected]> wrote in message
news:[email protected]...
>
> thanks for taht info, where can we read more?
>
>
> --
> FreakyAye
"GSM 03.22, 04.08 and 05.02 are the best places to start."
More generally start with the 02 series documents and work up, as you get
higher it generally gets more complex and increases the "depth" of
information.
03 is a general overview of the system
04 is protocol & procedures details
05 is radio layer stuff
06 is codecs etc
And you get the idea =)
- 09-13-2006, 11:59 PM #11Kralizec CraigGuest
Re: GSM Booting sequence
[email protected] writes:
>I want to know how a gsm mobile gets connected to its network for the
>first time when it powered up for the first time given there are six
>other gsm operators working. Can anyone help me out?
There are only three GSM operators - Telstra, Optus and Vodafone. All the
other companies re-sell access to one of those core networks.
Craig.
--
SUN RIPENED KERNELS - Surplus Sun Microsystems Equipment, Parts + Accessories
Location: Sydney, Australia - Phone: 02-9520-2547 - Fax: 02-9520-2557
Web: http://www.sunrk.com.au - Ebay: http://stores.ebay.com.au/id=19975645
Forums: http://www.sunshack.org/phpBB2/portal.php - Mobile: 04-2163-0547
- 09-14-2006, 04:51 AM #12Jeremy QuirkeGuest
Re: GSM Booting sequence
"Kralizec Craig" <[email protected]> wrote in message
news:[email protected]...
> [email protected] writes:
>
>>I want to know how a gsm mobile gets connected to its network for the
>>first time when it powered up for the first time given there are six
>>other gsm operators working. Can anyone help me out?
>
> There are only three GSM operators - Telstra, Optus and Vodafone. All the
> other companies re-sell access to one of those core networks.
>
> Craig.
>
He may have just been illustrating a point of how does an MS locate the
correct network when there are numerous networks.
- 09-14-2006, 04:51 AM #13Jeremy QuirkeGuest
Re: GSM Booting sequence
"Kralizec Craig" <[email protected]> wrote in message
news:[email protected]...
> [email protected] writes:
>
>>I want to know how a gsm mobile gets connected to its network for the
>>first time when it powered up for the first time given there are six
>>other gsm operators working. Can anyone help me out?
>
> There are only three GSM operators - Telstra, Optus and Vodafone. All the
> other companies re-sell access to one of those core networks.
>
> Craig.
>
He may have just been illustrating a point of how does an MS locate the
correct network when there are numerous networks.
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