12 thoughts on “Some help configuring GE864GPS-QUAD module to stay using the HPLMN Band when out of coverage”
I need to make sure the following functionality is implemented in our devices.
1) At first power up, the device should only attach to the Home PLMN. If I am correct setting AUTOBND=2 will ensure this occurs.
2) If our device has powered up, attached to the HPLMN correctly and at some stage goes into an area of land where there is no GSM coverage of any kind for the HPLMN, it should not attempt to try and find another band. We want it to stay using the band that it selected the first time it was powered up (i.e. the Home PLMN). The only time it should change band is when it is romaing in another country and tries an IMSI attach Procedure. When it is in the home country it should only ever stay using the Home PLMN.
I washoping that by setting the AUTOBND to 2 it would have ensured that the Telit module always stays on the HPLMN band whether it goes out of coverage or loses power but I am not so sure. I know AUTOBND relates to how the GE864GPS module searches for bands but I also know that how you set COPS also plays a part.
I did get an email from Telit support indicating that the module implements logic as per the ETSI 3GPP standards (ETSI 03.22 or 3GPP 23.122).
PLMN is choosen following the procedure as per section "4.4.3.1 At switch-on or recovery from lack of coverage",
A) The PLMN stored in the SIM, used during last valid registration. B) The home network if it is available (based on MCC and MNC from IMSI) C) then one on the list of networks from the Preferred PLMN List (EFPLMNSEL on SIM card) in priority order excluding the previously selected PLMN D) then PLMN with a received signal level above -85 dBm in random order excluding the previously selected PLMN E) then any other PLMN excluding the previously selected PLMN in order of decreasing signal strength or alternatively the previously selected PLMN may be chosen ignoring its signal strength. F) when a network is chosen, it will remain there unless the network loses the radio coverage. Even if the device is powered off.
At the moment I think our Telit module might be trying to find another band when it finds itself in a situation where there is no GSM coverage from the HPLMN. I think that it is finding a band of a competitor and staying on that band thereafter. The device that we have lost all communication with has AUTOBND=1.
Can I ask is my logic correct in saying that the Telit module will go looking for another band if GSM coverage of the existing band is lost. This is where AUTOBND is set to 1 and there is no Preferred list of other networks on the SIM and no blacklist. I think the cars in which we have the devices are driving to remote locations where the HPLMN does not have coverage and they are moving into an area where a competitors network has coverage.
as an FYI, we cannot configure the modules individually, they leave the manufacturers with a standard module configuration so I need the logic to stay in the Home PLMN (while in the home country) to be implemented from the AT configuration values that were set when we built the devices.
If anyone knows what configuration will provide the logic I need or any information about what is needed, I will be very grateful.
I need to make sure the following functionality is implemented in our devices.
1) At first power up, the device should only attach to the Home PLMN.
If I am correct setting AUTOBND=2 will ensure this occurs.
AUTOBND=2 means automatic selection of the bands 850/900/1800/1900MHz. By default the GE864-GPS works on EU bands only (900/1800), i.e. it cannot search for Americas bands (850/1900). So HPLMN is searched on one of the four bands, if not found, the module tries to get registered to another PLMN in roaming.
2) If our device has powered up, attached to the HPLMN correctly and at some stage goes into an area of land where there is no GSM coverage of any kind for the HPLMN, it should not attempt to try and find another band. We want it to stay using the band that it selected the first time it was powered up (i.e. the Home PLMN). The only time it should change band is when it is romaing in another country and tries an IMSI attach Procedure. When it is in the home country it should only ever stay using the Home PLMN.
I washoping that by setting the AUTOBND to 2 it would have ensured that the Telit module always stays on the HPLMN band whether it goes out of coverage or loses power but I am not so sure. I know AUTOBND relates to how the GE864GPS module searches for bands but I also know that how you set COPS also plays a part.
The band is the frequency range on which the module can operate. For each band there are several channels (e.g. 900MHz, ch 975 – 1023 and 0 – 124) and each channel can be allocated to one Network Operator (PLMN). So in a single band as 900MHz there could be different operators including the Home Network (HPLMN).
Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed.
This is how the module operates in AT+COPS=0 (automatic network selection).
If you want to select a specific operator, you have to set the manual selection AT+COPS=1,2,"mccmnc"
I did get an email from Telit support indicating that the module implements logic as per the ETSI 3GPP standards (ETSI 03.22 or 3GPP 23.122).
PLMN is choosen following the procedure as per section "4.4.3.1 At switch-on or recovery from lack of coverage",
A) The PLMN stored in the SIM, used during last valid registration. B) The home network if it is available (based on MCC and MNC from IMSI) C) then one on the list of networks from the Preferred PLMN List (EFPLMNSEL on SIM card) in priority order excluding the previously selected PLMN D) then PLMN with a received signal level above -85 dBm in random order excluding the previously selected PLMN E) then any other PLMN excluding the previously selected PLMN in order of decreasing signal strength or alternatively the previously selected PLMN may be chosen ignoring its signal strength. F) when a network is chosen, it will remain there unless the network loses the radio coverage. Even if the device is powered off.
At the moment I think our Telit module might be trying to find another band when it finds itself in a situation where there is no GSM coverage from the HPLMN. I think that it is finding a band of a competitor and staying on that band thereafter. The device that we have lost all communication with has AUTOBND=1.
Can I ask is my logic correct in saying that the Telit module will go looking for another band if GSM coverage of the existing band is lost. This is where AUTOBND is set to 1 and there is no Preferred list of other networks on the SIM and no blacklist. I think the cars in which we have the devices are driving to remote locations where the HPLMN does not have coverage and they are moving into an area where a competitors network has coverage.
as an FYI, we cannot configure the modules individually, they leave the manufacturers with a standard module configuration so I need the logic to stay in the Home PLMN (while in the home country) to be implemented from the AT configuration values that were set when we built the devices.
If anyone knows what configuration will provide the logic I need or any information about what is needed, I will be very grateful.
as I said is not a matter of bands or not only. The module can stay on the same band of the HPLMN and find another PLMN, if HPLM is not available.
About AUTOBND=1, at power on it searches for an available PLMN (based on 3GPP specs), starting from a couple of bands e.g. #BND=0 and switching to AT#BND=3 after 90s in case no PLMN has been found. Once it find a PLMN it stops the band scanning and stays on the BND selection ( 0 – 900/1800 or 3 -850/1900) till the module is powered off or reset.
It is obsolete and it should not be used specially in countries (Latin America) where operators use a mix of EU and US bands.
I need to make sure the following functionality is implemented in our devices.
1) At first power up, the device should only attach to the Home PLMN.
If I am correct setting AUTOBND=2 will ensure this occurs.
AUTOBND=2
means automatic selection of the bands 850/900/1800/1900MHz. By default
the GE864-GPS works on EU bands only (900/1800), i.e. it cannot search
for Americas bands (850/1900). So HPLMN is searched on one of the four
bands, if not found, the module tries to get registered to another PLMN
in roaming.
2) If our
device has powered up, attached to the HPLMN correctly and at some
stage goes into an area of land where there is no GSM coverage of any
kind for the HPLMN, it should not attempt to try and find another band.
We want it to stay using the band that it selected the first time it
was powered up (i.e. the Home PLMN). The only time it should change
band is when it is romaing in another country and tries an IMSI attach
Procedure. When it is in the home country it should only ever stay
using the Home PLMN.
I washoping that by
setting the AUTOBND to 2 it would have ensured that the Telit module
always stays on the HPLMN band whether it goes out of coverage or loses
power but I am not so sure. I know AUTOBND relates to how the GE864GPS
module searches for bands but I also know that how you set COPS also
plays a part.
The band is the frequency range
on which the module can operate. For each band there are several
channels (e.g. 900MHz, ch 975 – 1023 and 0 – 124) and each channel can
be allocated to one Network Operator (PLMN). So in a single band as
900MHz there could be different operators including the Home Network
(HPLMN).
Therefore when the module stays in its home
country (depending on the SIM), it will normally try to get registered
to the HPLMN. In case the HPLMN is not available, it will try to camp to
another PLMN in roaming. Since national roaming is not allowed by most
of the network operator, the module will camp in "emergency mode" to one
of the available PLMNs. Emergency mode means that only emergency calls
are allowed.
This is how the module operates in AT+COPS=0 (automatic network selection).
If you want to select a specific operator, you have to set the manual selection AT+COPS=1,2,"mccmnc"
I did get an email from Telit support indicating that the module
implements logic as per the ETSI 3GPP standards (ETSI 03.22 or 3GPP
23.122).
PLMN is choosen following the procedure as per section "4.4.3.1 At switch-on or recovery from lack of coverage",
A) The PLMN stored in the SIM, used during last valid registration. B) The home network if it is available (based on MCC and MNC from IMSI) C)
then one on the list of networks from the Preferred PLMN List
(EFPLMNSEL on SIM card) in priority order excluding the previously
selected PLMN D) then PLMN with a received signal level above -85 dBm in random order excluding the previously selected PLMN E)
then any other PLMN excluding the previously selected PLMN in order of
decreasing signal strength or alternatively the previously selected
PLMN may be chosen ignoring its signal strength. F) when a network
is chosen, it will remain there unless the network loses the radio
coverage. Even if the device is powered off.
At
the moment I think our Telit module might be trying to find another
band when it finds itself in a situation where there is no GSM coverage
from the HPLMN. I think that it is finding a band of a competitor and
staying on that band thereafter. The device that we have lost all
communication with has AUTOBND=1.
Can I ask is my
logic correct in saying that the Telit module will go looking for
another band if GSM coverage of the existing band is lost. This is
where AUTOBND is set to 1 and there is no Preferred list of other
networks on the SIM and no blacklist. I think the cars in which we have
the devices are driving to remote locations where the HPLMN does not
have coverage and they are moving into an area where a competitors
network has coverage.
as an FYI, we cannot
configure the modules individually, they leave the manufacturers with a
standard module configuration so I need the logic to stay in the Home
PLMN (while in the home country) to be implemented from the AT
configuration values that were set when we built the devices.
If
anyone knows what configuration will provide the logic I need or any
information about what is needed, I will be very grateful.
as
I said is not a matter of bands or not only. The module can stay on the
same band of the HPLMN and find another PLMN, if HPLM is not available.
About
AUTOBND=1, at power on it searches for an available PLMN (based on 3GPP
specs), starting from a couple of bands e.g. #BND=0 and switching to
AT#BND=3 after 90s in case no PLMN has been found. Once it find a PLMN
it stops the band scanning and stays on the BND selection ( 0 – 900/1800
or 3 -850/1900) till the module is powered off or reset.
It is obsolete and it should not be used specially in countries (Latin America) where operators use a mix of EU and US bands.
Andrea,
Thank you for the update.
On the AUTOBND=1, we have modified this to be AUTOBND=2.
we also have COPS=0 for automatic network selection.
In the section where you clarified the behaviour of the module when the HPLMN isnt available,
"Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed."
Can i ask, will the device stays camped in "emergency mode" to one of the other available PLMN bands, does the Telit module try to move back to the band of the Home PLMN when it comes back into coverage (where the HPLMn frequency is again available). For a device that has AUTOBND=1, I think that we are staying in that emergency mode on the other network operatoes band. This would explain why we have lost communication with the device.
If we reset the module to AUTOBND=2, I am hoping that this will cause the module to always move back to the HPLMN and out of emergency mode whenever the Home PLMN is again available.
I thik I am close to understanding exactly what the problem is so thank you for your help so far. any help answering my other few questions would be very much appreciated.
Regards
Hi Andrea,
thank for for the information.
We have already begun to reset out AUTOBND=2 and we use COP=0 (Automatic Network selection)
where you stated
"Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed."
can i ask, if we have a device with AUTOBND=1 will the Telit module try to re-establish a connection on the HPLMN when it comes back into coverage or will it stay camped on the another networks band. I think this is exactly the problem we are having.
I am also hoping that with AUTOBND=2 that if our devivce ever goes out of coverage and and the telit odule does camp on another network to support emergencty calls, that it will go back to the Home PLMN when it returns to an area of coverage. I am not sure how this is detected but I think our problem is that we are staying camped on the other network and we are not moving back to the HPLMN band.
thank you for the support so far.
regards
Paul.
mhmm it depends on which is the home network and in which country is operating the module.
e.g.1) the module is in Ireland where only 900/1800MHz bands are available. With AT#AUTOBND=1 the module at power on will start searching for first couple of bands (by default will start from #BND=0 – 900/1800), it will find the HPLMN (e.g. Vodafone) and it will stay working on BND=0. In case Vodafone is no more available it will camp to another operator e.g. O2 in emergency and periodically it will scan for HPLM on 900/1800MHz bands
e.g.2) the module is in Brasil where 850/900/1800/1900MHz bands are available. With AT#AUTOBND=1 the module at power on starts serching for first couple of bands (by default will start from #BND=0 – 900/1800). If TIM Brasil (HPLM) which is covered on 1800MHz band only is not available, module will scan for other PLMNs on #BND=0. If after 90s, no PLMNs are found, it will switch to #BND=3 start searching on 850/1900 bands. If it find an operator e.g. VIVO on 1900MHz it will stop band searching and stay on #BND=3 selection 8500/1900MHz bands. In case the module won’t be able to scan again on 900/1800 bands searching for TIM operator unless it is reset on power cycled.
Do not confuse band selection with network selection.
Network selection is handled by AT+COPS in automatic or manual mode. In automatic mode, network timers are defined to periodically start a new network scan in order to perform a location update procedure (registration).
mhmm it depends on which is the home network and in which country is operating the module.
e.g.1)
the module is in Ireland where only 900/1800MHz bands are available.
With AT#AUTOBND=1 the module at power on will start searching for first
couple of bands (by default will start from #BND=0 – 900/1800), it will
find the HPLMN (e.g. Vodafone) and it will stay working on BND=0. In
case Vodafone is no more available it will camp to another operator e.g.
O2 in emergency and periodically it will scan for HPLM on 900/1800MHz
bands
e.g.2) the module is in Brasil where
850/900/1800/1900MHz bands are available. With AT#AUTOBND=1 the module
at power on starts serching for first couple of bands (by default will
start from #BND=0 – 900/1800). If TIM Brasil (HPLM) which is covered on
1800MHz band only is not available, module will scan for other PLMNs on
#BND=0. If after 90s, no PLMNs are found, it will switch to #BND=3 start
searching on 850/1900 bands. If it find an operator e.g. VIVO on
1900MHz it will stop band searching and stay on #BND=3 selection
8500/1900MHz bands. In case the module won’t be able to scan again on
900/1800 bands searching for TIM operator unless it is reset on power
cycled.
Do not confuse band selection with network selection.
Network
selection is handled by AT+COPS in automatic or manual mode. In
automatic mode, network timers are defined to periodically start a new
network scan in order to perform a location update procedure
(registration).
Andrea,
It is St Lucia and the Home PLMN has 900/1800 and 1900 bands. The other operator is using 850MHz.
I am getting confirmation from the home plmn to see if 900 is the 2G band.
My understanding of AUTOBND=1 in that country is that it will start at the 900MHz band. It will succeed in an IMSI attach Procedure to that network and then it stays there having succesfully established the IMSI attach. This is akin to you saying ithat is stays working on #BND=0. We know this works becuase the devices were communicating successfully on the 900/1800 band (BND=0)
the other operator is using 850MHz.so I wondering if, when the module goes out of BND-0 coverage, it camps on the 850MHz band (BND=3) to enable "emergency calls" but I think we could be staying camped on that 850MHz band either becuase we ahave configured AUTOBND=1. I still dont understand if AUTOBND=2 will keep BND=0 (i.e. the HPLMN band) and revert back to this when it comes back into a coverage area.
Ideally I would like the module to revert back to BND-0 after it had supported emergency calls on a BND-3 network (when out of coverage of the HPLMN)
cheers.
Andrea,
I had forgot to mention,
when we ship our devices they can go to any country to be deployed. This is why we do not specifically use AT+COPS=1,2,"mccmnc" and instead opt for automatic Network Selection.
When indicated "Network selection is handled by AT+COPS in automatic or manual mode. In automatic mode, network timers are defined to periodically start a new network scan in order to perform a location update procedure (registration)."
are the network timers indicated by the network to whom the device attaces? I am assuming this is something the networks do to periodically to refresh the actual location (BSS, cell-site, VLR back to the HLR). If this is the case, does it mean the module goes through a list of available ntworks at the band that it settled on and picks the HPLMN if avauilable, before attemtping another operator.
from one of your previous responses I also noted "The module can stay on the same band of the HPLMN and find another PLMN, if HPLM is not available.". does this relate to what you were saying above.
cheers
Andrea,
It is St Lucia and the Home PLMN has 900/1800 and 1900 bands. The other operator is using 850MHz.
I am getting confirmation from the home plmn to see if 900 is the 2G band.
My understanding of AUTOBND=1 in that country is that it will start at the 900MHz band. It will succeed in an IMSI attach Procedure to that network and then it stays there having succesfully established the IMSI attach. This is akin to you saying ithat is stays working on #BND=0. We know this works becuase the devices were communicating successfully on the 900/1800 band (BND=0)
the other operator is using 850MHz.so I wondering if, when the module goes out of BND-0 coverage, it camps on the 850MHz band (BND=3) to enable "emergency calls" but I think we could be staying camped on that 850MHz band either becuase we ahave configured AUTOBND=1. I still dont understand if AUTOBND=2 will keep BND=0 (i.e. the HPLMN band) and revert back to this when it comes back into a coverage area.
No, in AUTOBND=1 mode, the module remains in the bands he found at power on, so in case it was #BND=0, it cannot get registered to 850MHz band unless the module is reset,
Refering to the above networks, it is also possible that the module at power on get registered to Digitel at 1900MHz ( in case that area is covered only by this frequency). In this case the module will keep #BND=3 setting, and it will never register to Digitel on 900/1800.
AT#AUTOBND=2 doesn’t consider #BND settings. It is a real full band detection that allows the module to work on all the 4 GSM bands in any condition.
Ideally I would like the module to revert back to BND-0 after it had supported emergency calls on a BND-3 network (when out of coverage of the HPLMN)
cheers.
Andrea,
We retrived the device from the country where the connection was lost. As expected the module was camped on Band 0 (900MHz/1800MHz). This is consistent with the device working for a few works without issue on the HPLMN.
The problem seem sto be with Network Selection (once the band is established).
We have AT=COPS=0 for automatic network selection.
Our engineering team are in europe and we expected the device to be able to register on a local PLMN (other devices sent back for analysis do this no problem) but the device failed to register on any of the available networks.
We took out the SIM in the moduile (from the originating country where the issue occured) and put in another SIM from another country in the same region. This time the Device registered on a local network and established a GPRs connection.
The team then put the first SIM into a normal Mobile phone and it too could not register on any local network.
From this my assumption is that either the SIM subscription doesnt allow internaional roaming (which could cause a failed registeration) or there is something possibly wrong with the SIM that doesnt allow any other network other than the HPLMN to connect. I have asked the operator to check the SIM for any barring profiles. If they have an international barring service turned on, I have asked for them to turn that off to see if the SIM does find a local network when roaming,
My issue is stil around when the device goes out of coverage and why it doesnt come back into coverage. With COPS=0 the device should select the HPLMN when it comes back into coverage and, if roaming shuld be able to select a foreign PLMN.
Can i get your thoughts on this please to see if my understanding is correct.
Regards
Paul.
Hi Paul,
I assume roaming service depends on the SIM contract you have.
Yes COPS=0 automatic mode, the module selects and attempts to perform a Location Registration on the registered PLMN (latest one), if not available it should select other PLMNs in the following order: i) HPLMN (if not previously selected); ii) each PLMN in the "PLMN Selector" data field in the SIM (in priority order); iii) other PLMNs with received signal level above -85 dBm in random order; iv) all other PLMNs in order of decreasing signal strength.
Without at least a log it is quite impossible to know why the devise doesn’t come back into coverage.
I need to make sure the following functionality is implemented in our devices.
1) At first power up, the device should only attach to the Home PLMN. If I am correct setting AUTOBND=2 will ensure this occurs.
2) If our device has powered up, attached to the HPLMN correctly and at some stage goes into an area of land where there is no GSM coverage of any kind for the HPLMN, it should not attempt to try and find another band. We want it to stay using the band that it selected the first time it was powered up (i.e. the Home PLMN). The only time it should change band is when it is romaing in another country and tries an IMSI attach Procedure. When it is in the home country it should only ever stay using the Home PLMN.
I washoping that by setting the AUTOBND to 2 it would have ensured that the Telit module always stays on the HPLMN band whether it goes out of coverage or loses power but I am not so sure. I know AUTOBND relates to how the GE864GPS module searches for bands but I also know that how you set COPS also plays a part.
I did get an email from Telit support indicating that the module implements logic as per the ETSI 3GPP standards (ETSI 03.22 or 3GPP 23.122).
PLMN is choosen following the procedure as per section "4.4.3.1 At switch-on or recovery from lack of coverage",
A) The PLMN stored in the SIM, used during last valid registration.
B) The home network if it is available (based on MCC and MNC from IMSI)
C) then one on the list of networks from the Preferred PLMN List (EFPLMNSEL on SIM card) in priority order excluding the previously selected PLMN
D) then PLMN with a received signal level above -85 dBm in random order excluding the previously selected PLMN
E) then any other PLMN excluding the previously selected PLMN in order of decreasing signal strength or alternatively the previously selected PLMN may be chosen ignoring its signal strength.
F) when a network is chosen, it will remain there unless the network loses the radio coverage. Even if the device is powered off.
At the moment I think our Telit module might be trying to find another band when it finds itself in a situation where there is no GSM coverage from the HPLMN. I think that it is finding a band of a competitor and staying on that band thereafter. The device that we have lost all communication with has AUTOBND=1.
Can I ask is my logic correct in saying that the Telit module will go looking for another band if GSM coverage of the existing band is lost. This is where AUTOBND is set to 1 and there is no Preferred list of other networks on the SIM and no blacklist. I think the cars in which we have the devices are driving to remote locations where the HPLMN does not have coverage and they are moving into an area where a competitors network has coverage.
as an FYI, we cannot configure the modules individually, they leave the manufacturers with a standard module configuration so I need the logic to stay in the Home PLMN (while in the home country) to be implemented from the AT configuration values that were set when we built the devices.
If anyone knows what configuration will provide the logic I need or any information about what is needed, I will be very grateful.
AUTOBND=2 means automatic selection of the bands 850/900/1800/1900MHz. By default the GE864-GPS works on EU bands only (900/1800), i.e. it cannot search for Americas bands (850/1900). So HPLMN is searched on one of the four bands, if not found, the module tries to get registered to another PLMN in roaming.
The band is the frequency range on which the module can operate. For each band there are several channels (e.g. 900MHz, ch 975 – 1023 and 0 – 124) and each channel can be allocated to one Network Operator (PLMN). So in a single band as 900MHz there could be different operators including the Home Network (HPLMN).
Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed.
This is how the module operates in AT+COPS=0 (automatic network selection).
If you want to select a specific operator, you have to set the manual selection AT+COPS=1,2,"mccmnc"
as I said is not a matter of bands or not only. The module can stay on the same band of the HPLMN and find another PLMN, if HPLM is not available.
About AUTOBND=1, at power on it searches for an available PLMN (based on 3GPP specs), starting from a couple of bands e.g. #BND=0 and switching to AT#BND=3 after 90s in case no PLMN has been found. Once it find a PLMN it stops the band scanning and stays on the BND selection ( 0 – 900/1800 or 3 -850/1900) till the module is powered off or reset.
It is obsolete and it should not be used specially in countries (Latin America) where operators use a mix of EU and US bands.
AUTOBND=2
means automatic selection of the bands 850/900/1800/1900MHz. By default
the GE864-GPS works on EU bands only (900/1800), i.e. it cannot search
for Americas bands (850/1900). So HPLMN is searched on one of the four
bands, if not found, the module tries to get registered to another PLMN
in roaming.
The band is the frequency range
on which the module can operate. For each band there are several
channels (e.g. 900MHz, ch 975 – 1023 and 0 – 124) and each channel can
be allocated to one Network Operator (PLMN). So in a single band as
900MHz there could be different operators including the Home Network
(HPLMN).
Therefore when the module stays in its home
country (depending on the SIM), it will normally try to get registered
to the HPLMN. In case the HPLMN is not available, it will try to camp to
another PLMN in roaming. Since national roaming is not allowed by most
of the network operator, the module will camp in "emergency mode" to one
of the available PLMNs. Emergency mode means that only emergency calls
are allowed.
This is how the module operates in AT+COPS=0 (automatic network selection).
If you want to select a specific operator, you have to set the manual selection AT+COPS=1,2,"mccmnc"
as
I said is not a matter of bands or not only. The module can stay on the
same band of the HPLMN and find another PLMN, if HPLM is not available.
About
AUTOBND=1, at power on it searches for an available PLMN (based on 3GPP
specs), starting from a couple of bands e.g. #BND=0 and switching to
AT#BND=3 after 90s in case no PLMN has been found. Once it find a PLMN
it stops the band scanning and stays on the BND selection ( 0 – 900/1800
or 3 -850/1900) till the module is powered off or reset.
It is obsolete and it should not be used specially in countries (Latin America) where operators use a mix of EU and US bands.
Andrea,
Thank you for the update.
On the AUTOBND=1, we have modified this to be AUTOBND=2.
we also have COPS=0 for automatic network selection.
In the section where you clarified the behaviour of the module when the HPLMN isnt available,
"Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed."
Can i ask, will the device stays camped in "emergency mode" to one of the other available PLMN bands, does the Telit module try to move back to the band of the Home PLMN when it comes back into coverage (where the HPLMn frequency is again available). For a device that has AUTOBND=1, I think that we are staying in that emergency mode on the other network operatoes band. This would explain why we have lost communication with the device.
If we reset the module to AUTOBND=2, I am hoping that this will cause the module to always move back to the HPLMN and out of emergency mode whenever the Home PLMN is again available.
I thik I am close to understanding exactly what the problem is so thank you for your help so far. any help answering my other few questions would be very much appreciated.
Regards
Hi Andrea,
thank for for the information.
We have already begun to reset out AUTOBND=2 and we use COP=0 (Automatic Network selection)
where you stated
"Therefore when the module stays in its home country (depending on the SIM), it will normally try to get registered to the HPLMN. In case the HPLMN is not available, it will try to camp to another PLMN in roaming. Since national roaming is not allowed by most of the network operator, the module will camp in "emergency mode" to one of the available PLMNs. Emergency mode means that only emergency calls are allowed."
can i ask, if we have a device with AUTOBND=1 will the Telit module try to re-establish a connection on the HPLMN when it comes back into coverage or will it stay camped on the another networks band. I think this is exactly the problem we are having.
I am also hoping that with AUTOBND=2 that if our devivce ever goes out of coverage and and the telit odule does camp on another network to support emergencty calls, that it will go back to the Home PLMN when it returns to an area of coverage. I am not sure how this is detected but I think our problem is that we are staying camped on the other network and we are not moving back to the HPLMN band.
thank you for the support so far.
regards
Paul.
mhmm it depends on which is the home network and in which country is operating the module.
e.g.1) the module is in Ireland where only 900/1800MHz bands are available. With AT#AUTOBND=1 the module at power on will start searching for first couple of bands (by default will start from #BND=0 – 900/1800), it will find the HPLMN (e.g. Vodafone) and it will stay working on BND=0. In case Vodafone is no more available it will camp to another operator e.g. O2 in emergency and periodically it will scan for HPLM on 900/1800MHz bands
e.g.2) the module is in Brasil where 850/900/1800/1900MHz bands are available. With AT#AUTOBND=1 the module at power on starts serching for first couple of bands (by default will start from #BND=0 – 900/1800). If TIM Brasil (HPLM) which is covered on 1800MHz band only is not available, module will scan for other PLMNs on #BND=0. If after 90s, no PLMNs are found, it will switch to #BND=3 start searching on 850/1900 bands. If it find an operator e.g. VIVO on 1900MHz it will stop band searching and stay on #BND=3 selection 8500/1900MHz bands. In case the module won’t be able to scan again on 900/1800 bands searching for TIM operator unless it is reset on power cycled.
Do not confuse band selection with network selection.
Network selection is handled by AT+COPS in automatic or manual mode. In automatic mode, network timers are defined to periodically start a new network scan in order to perform a location update procedure (registration).
mhmm it depends on which is the home network and in which country is operating the module.
e.g.1)
the module is in Ireland where only 900/1800MHz bands are available.
With AT#AUTOBND=1 the module at power on will start searching for first
couple of bands (by default will start from #BND=0 – 900/1800), it will
find the HPLMN (e.g. Vodafone) and it will stay working on BND=0. In
case Vodafone is no more available it will camp to another operator e.g.
O2 in emergency and periodically it will scan for HPLM on 900/1800MHz
bands
e.g.2) the module is in Brasil where
850/900/1800/1900MHz bands are available. With AT#AUTOBND=1 the module
at power on starts serching for first couple of bands (by default will
start from #BND=0 – 900/1800). If TIM Brasil (HPLM) which is covered on
1800MHz band only is not available, module will scan for other PLMNs on
#BND=0. If after 90s, no PLMNs are found, it will switch to #BND=3 start
searching on 850/1900 bands. If it find an operator e.g. VIVO on
1900MHz it will stop band searching and stay on #BND=3 selection
8500/1900MHz bands. In case the module won’t be able to scan again on
900/1800 bands searching for TIM operator unless it is reset on power
cycled.
Do not confuse band selection with network selection.
Network
selection is handled by AT+COPS in automatic or manual mode. In
automatic mode, network timers are defined to periodically start a new
network scan in order to perform a location update procedure
(registration).
Andrea,
It is St Lucia and the Home PLMN has 900/1800 and 1900 bands. The other operator is using 850MHz.
I am getting confirmation from the home plmn to see if 900 is the 2G band.
My understanding of AUTOBND=1 in that country is that it will start at the 900MHz band. It will succeed in an IMSI attach Procedure to that network and then it stays there having succesfully established the IMSI attach. This is akin to you saying ithat is stays working on #BND=0. We know this works becuase the devices were communicating successfully on the 900/1800 band (BND=0)
the other operator is using 850MHz.so I wondering if, when the module goes out of BND-0 coverage, it camps on the 850MHz band (BND=3) to enable "emergency calls" but I think we could be staying camped on that 850MHz band either becuase we ahave configured AUTOBND=1. I still dont understand if AUTOBND=2 will keep BND=0 (i.e. the HPLMN band) and revert back to this when it comes back into a coverage area.
Ideally I would like the module to revert back to BND-0 after it had supported emergency calls on a BND-3 network (when out of coverage of the HPLMN)
cheers.
Andrea,
I had forgot to mention,
when we ship our devices they can go to any country to be deployed. This is why we do not specifically use AT+COPS=1,2,"mccmnc" and instead opt for automatic Network Selection.
When indicated "Network selection is handled by AT+COPS in automatic or manual mode. In automatic mode, network timers are defined to periodically start a new network scan in order to perform a location update procedure (registration)."
are the network timers indicated by the network to whom the device attaces? I am assuming this is something the networks do to periodically to refresh the actual location (BSS, cell-site, VLR back to the HLR). If this is the case, does it mean the module goes through a list of available ntworks at the band that it settled on and picks the HPLMN if avauilable, before attemtping another operator.
from one of your previous responses I also noted "The module can stay on the same band of the HPLMN and find another PLMN, if HPLM is not available.". does this relate to what you were saying above.
cheers
there is only 2G coverage in Saint Lucia: http://maps.mobileworldlive.com/network.php?cid=159&cname=Saint%20Lucia
No, in AUTOBND=1 mode, the module remains in the bands he found at power on, so in case it was #BND=0, it cannot get registered to 850MHz band unless the module is reset,
Refering to the above networks, it is also possible that the module at power on get registered to Digitel at 1900MHz ( in case that area is covered only by this frequency). In this case the module will keep #BND=3 setting, and it will never register to Digitel on 900/1800.
AT#AUTOBND=2 doesn’t consider #BND settings. It is a real full band detection that allows the module to work on all the 4 GSM bands in any condition.
Andrea,
We retrived the device from the country where the connection was lost. As expected the module was camped on Band 0 (900MHz/1800MHz). This is consistent with the device working for a few works without issue on the HPLMN.
The problem seem sto be with Network Selection (once the band is established).
We have AT=COPS=0 for automatic network selection.
Our engineering team are in europe and we expected the device to be able to register on a local PLMN (other devices sent back for analysis do this no problem) but the device failed to register on any of the available networks.
We took out the SIM in the moduile (from the originating country where the issue occured) and put in another SIM from another country in the same region. This time the Device registered on a local network and established a GPRs connection.
The team then put the first SIM into a normal Mobile phone and it too could not register on any local network.
From this my assumption is that either the SIM subscription doesnt allow internaional roaming (which could cause a failed registeration) or there is something possibly wrong with the SIM that doesnt allow any other network other than the HPLMN to connect. I have asked the operator to check the SIM for any barring profiles. If they have an international barring service turned on, I have asked for them to turn that off to see if the SIM does find a local network when roaming,
My issue is stil around when the device goes out of coverage and why it doesnt come back into coverage. With COPS=0 the device should select the HPLMN when it comes back into coverage and, if roaming shuld be able to select a foreign PLMN.
Can i get your thoughts on this please to see if my understanding is correct.
Regards
Paul.
Hi Paul,
I assume roaming service depends on the SIM contract you have.
http://www.digicelstlucia.com/en/coverage_roaming/roaming-partners
Yes COPS=0 automatic mode, the module selects and attempts to perform a Location Registration on the registered PLMN (latest one), if not available it should select other PLMNs in the following order:
i) HPLMN (if not previously selected);
ii) each PLMN in the "PLMN Selector" data field in the SIM (in priority order);
iii) other PLMNs with received signal level above -85 dBm in random order;
iv) all other PLMNs in order of decreasing signal strength.
Without at least a log it is quite impossible to know why the devise doesn’t come back into coverage.