GSM protocols

hi,
i have a confusion about the activities of MOBILE just after the switch on…
means what are the procedureit go through for
1. PLMN selection
2. Cell selection
GSM 3.22 rec says that MS will first select PLMN and then suitable cell though logically its right but howcome an MS will select PLMN before camping on a cell .
also their is a restriction of scanning 30 RF channel for GSM so which 30 channel it will select?
if u clarify this whole proccedure that will be great help for me.
regards
suvendu

dear Mr BOKO,
is their any constrains of no of channel it will scan just after switch on and is their any relation with signal strength ?
if their is some formal procedure for network selection that pls tell me also

Hi Suvendu,

I would like to answer your query regarding formal procedure for network selection.Actually we have 2 choices of network selection either automatic or manual on the MS.But anyway ,I have copied the formal procedure as stated below.

Automatic Network selection; with information on preferred PLMN list
Description
If in automatic network selection mode, on being switched on, the MS shall perform an automatic network selection. The MS shall select the next available GSM network saved on the highest position of the Preferred PLMN list of the SIM card, when the HPLMN or the last registered PLMN is not available.
Related GSM core specifications
TS 22.011, subclause 3.2.2.2
Reason for test
To ensure that the automatic network selection procedure is correctly performed when roaming away from the HPLMN.
Initial configuration
MS is switched off, in automatic network selection mode, located outside the coverage area of the HPLMN, with a preferred PLMN list configured, and located on a VPLMN which it may select. The SIM card shall be a roaming SIM card with access to all available networks. The SIM card shall support preferably 50 (but not less than 32) entries on the Preferred PLMN list.
Before each test loop, the following data on the SIM card needs to be set to the following values:
Location Information (LOCI): FF FF FF FF FF FF FF FF 00 00 00 01
Forbidden PLMN: FF FF FF FF FF FF FF FF FF FF FF FF
Broadcast Control Channels: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PLMN Selector (Preferred PLMNs): MCC xxx / MNC yy on position 50 (32) or lower, all other fields are filled with network codes corresponding to networks not available at the test location.xxx and yy should be the MCC and MNC of one of the available networks.

Before each test loop, the MS shall perform successfully a location updating procedure at a System Simulator using a Simulator Test SIM card (001 01). The configuration of the System Simulator shall be MCC 001 and MNC 01 at ARFCN 124 (check that ARFCN 124 is not used by one of the networks in the field). After the successful location updating procedure the MS shall be turned off by its power button (not by removing the battery) to ensure that the simulator’s network information is stored in the mobile and test SIM card. This procedure shall ensure that the terminal is not containing any information about any GSM networks present in the field in its memory.
The test shall be carried out at a location, where not less than 3 networks are available with a field strength better than –85 dBm (preferably at least –70 dBm). For terminals supporting GSM900 only, ensure that not less than 2 networks are available on GSM900 frequencies with a field strength better than –85 dBm (preferably at least –70 dBm). This can be proved using a reference terminal with a network monitor.
Test procedure
1. Turn on the mobile, and ensure that the correct PLMN is selected.
The test shall be performed 5 times. The initial configuration has to be restored before each test loop.
If the terminal selects a network different from xxx-yy, stop the test and set the xxx-yy network on position 32 of the Preferred PLMN list. Then restart testing.
If the terminal again selects a network different from xxx-yy, stop the test and set the xxx-yy network on position 20 of the Preferred PLMN list (and so on).
If the Roaming SIM Card has got only 32 positions for the Preferred PLMN list, start the test on position 32 and then step down to position 20, 10 etc.
2. Repeat as necessary with different SIMs having different preferred PLMN lists.
Expected behaviour
After each procedure, the MS shall always select the xxx-yy network.
Some MS only support a limited number of preferred PLMN; in that case, report the number of PLMN considered by the MS in the table of Annex B.
2.2 Automatic Network selection; without information on preferred PLMN list, RXLev > -85dBm
Description
If in automatic network selection mode and without a preferred PLMN list and when the HPLMN or the last registered PLMN is not available, the MS shall randomly select a GSM network, chosen out of a list of networks in which all networks are represented with a field strength better than –85 dBm. (If the received field strength is less than –85 dBm, the network with the highest field strength shall be selected).
Related GSM core specifications
TS 22.011, subclause 3.2.2.2
Reason for test
To ensure that the automatic network selection procedure is correctly performed when roaming away from the HPLMN.
Initial configuration
MS switched off, in automatic selection mode, without a preferred PLMN list configured, and located on a VPLMN which it may select. The HPLMN or the last registered PLMN is not available. The SIM card shall be a roaming SIM card with access to all available networks. Before each test loop, the following data on the SIM card needs to be set to its default values:
Location Information (LOCI): FF FF FF FF FF FF FF FF 00 00 00 01
Forbidden PLMN: FF FF FF FF FF FF FF FF FF FF FF FF
Broadcast Control Channels: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PLMN Selector (Preferred PLMNs): All deleted (all set to ‘F’)

Before each test loop, the MS shall perform successfully a location updating procedure at the System Simulator using a Simulator Test SIM card (001 01). The configuration of the System Simulator shall be MCC 001 and MNC 01 at ARFCN 124 (check that ARFCN 124 is not used by one of the networks in the field). After the location updating procedure the MS shall be turned off by its power button (not by removing the battery) to ensure that the simulator’s network information is stored in the mobile and test SIM card. This procedure shall ensure that the terminal is not containing any information about any GSM networks present in the field in its memory.
The test shall be carried out at a location, where not less than 3 networks are available with a field strength better than –85 dBm (preferably at least –70 dBm). For terminals supporting GSM900 only, ensure that not less than 2 networks are available on GSM900 frequencies with a field strength better than –85 dBm (preferably at least –70 dBm). This can be proved using a reference terminal with a network monitor.
Test procedure
The test shall be performed 5 times per network available with a field strength of better than –85 dBm. If no random balance can be seen, the test shall be repeated another 5 times per available network. The initial configuration has to be restored before each test loop.
Expected behaviour
After each procedure, the MS performs an automatic network selection. Automatic network selection shall ensure that the selection is random if RXLEV >-85 dBm.
2.3 Periodic HPLMN searching when in National Roaming
Description
If in automatic network selection mode, and roaming on a VPLMN in the home country, the MS should periodically attempt to select the HPLMN.
Related GSM core specifications
TS 23.122, subclause 4.4.3.3
Reason for test
To ensure that the periodic home network searching procedure is correctly performed when in national roaming.
Initial configuration
MS is switched on, in automatic network selection mode, located outside the coverage area of the HPLMN, and registered on a VPLMN in the home country. The SIM card shall have a national roaming access to another national network; the SIM card shall have the HPLMN timer set to a value between 6 and 30 minutes.
Test procedure
Move the terminal to an area where the HPLMN is present, while it is still in coverage of the VPLMN.
Expected behaviour
The terminal shall select the HPLMN in a time not greater than the time settled on the HPLMN timer.
2.4 Automatic network selection; available network stored in EFLOCI
Description
If in automatic network selection mode, and roaming in a foreign country where there are different suitable PLMNs, the MS shall select on power on the last used PLMN (that is stored in the EFLOCI field on the SIM card), irrespective of the configuration of the preferred PLMN list and the availability of the HPLMN.
Related GSM core specifications
TS 23.122, subclause 4.4.3.1
Reason for test
To ensure that the last used PLMN is automatically selected at power when in international roaming.
Initial configuration
MS is switched on, in automatic network selection mode, registered on a VPLMN, which is not stored on the preferred PLMN list, in a foreign country. The SIM card shall have an international roaming access to different suitable networks in the visited country. Both, networks on the preferred PLMN list and the HPLMN shall be available.
Test procedure
1. Switch off the MS, then switch it on. Verify that the last used PLMN is selected.
2. Switch off the MS, then move to an area where the last used PLMN is received with a signal strength less than that of other PLMNs. Switch on the MS and verify that the last used PLMN is selected.
3. Switch off the MS, then move to an area covered by another cell of the last used PLMN. Switch on the MS and verify that the last used PLMN is selected.
4. Switch off the MS, then move to an area covered by a cell in another location area of the last used PLMN. Switch on the MS and verify that the last used PLMN is selected.
5. Switch off the MS, then move to an area covered by a cell which is in a different band of the last used PLMN. Switch on the MS and verify that the last used PLMN is selected (applicable to dual-band mobiles only).
6. Switch off the MS, then move to an area covered by a cell which has channels in the EGSM band of the last used PLMN. Switch on the MS and verify that the last used PLMN is selected (applicable to EGSM mobiles only).
Expected behaviour
After each procedure, the MS shall always select the last used PLMN.
2.5 Manual Network selection
Description
If in manual network selection mode, the MS shall list all available PLMNs. This behaviour is independent from the content of the preferred PLMN list.
Related GSM core specifications
TS 22.011, subclause 3.2.2.2
Reason for test
To ensure that the correct list of PLMNs is displayed for the purposes of manual PLMN selection.
Initial configuration
MS switched on, in automatic selection mode.
Test procedure
1. Select the manual network selection mode on the MS and ensure that the list of all available PLMNs is displayed, and that the displayed networks can be selected, even if on the forbidden list.
2. Check that the preferred PLMN list is not changed after the manual network selection.
3. Repeat the test with different entries in the preferred PLMN lists, including the empty list and lists of more than 32 entries.
Expected behaviour
The MS shall display all available PLMNs and it shall perform manual network selection on the chosen network. The preferred PLMN list is not changed after the manual network selection.
2.6 Selection mode following switch off
Description
The MS shall be retain its configuration of automatic and manual network selection modes when switched off.
Related GSM core specifications
TS 22.011, subclause 3.2.2.2
Reason for test
To ensure that the MS retains its configuration of manual and automatic selection modes when switched off.
Initial configuration
MS in idle mode, with automatic network selection mode configured.
Test procedure
1. Change to manual network selection. Turn the MS off and on again. Check that the manual network selection mode is in use.
2. Change to automatic network selection. Turn the MS off and on again. Check that the automatic network selection mode is in use.
Expected behaviour
The MS has the same selection mode when switched on that it had when switched off.

3 Handover
3.1 Handover during an active call
Description
The MS shall correctly perform handover when commanded to by the network.
Related GSM core specifications
GSM 04.18 subclause 3
Reason for test
To ensure that the MS correctly performs handover and does not drop the call or interrupt transmission.
Initial configuration
MS with an active voice call in progress
Test procedure
Move from the coverage area of one cell to another. Ensure that the call is not dropped and that voice transmission is maintained in both directions.
Where possible, this procedure should be repeated in different locations to check that the different types handover that the network can command, involving as many as possible of the following combinations of features
1. Operation on different frequency bands
2. Handover between different codec types/rates
3. Handover between cells with and without frequency hopping
4. Finely synchronised, non-synchronised, pseudo-synchronised and pre-synchronised cells
5. Handover moving between the coverage areas of two different MSCs
6. Any possible combinations of the above.
7. Any combination of the above, but with a circuit-switched call in progress for other services, such as data or fax.
NOTE: To achieve the best possible coverage of these combinations may require co-operation from the network operator.
Expected behaviour
After the handover, the MS maintains a connection on the traffic channel (speech or data) in both directions, and does not drop the call within 30 seconds of the handover.

Hi Boko,

In connection to your question,I guess yes there is periodic, it depends on the PLMN that acquires the highest signal level ,therefore your roaming sim searches,and the MS should preferred the PLMN which has the highest signal level.

Carlos,

That’s an interesting question… I’m not sure about this either. Anyone knows ?

Thanks

call mature ? what is it ?

hi arvin it seems that u involved in some type of gsm testing job
r u?

looking for ur reply

regards