I have this GSM embedded device under linux, where depending on external factors I might chose to put a different sim card into. But in the configuration for the PPP, I have to give an APN, which changes depending on the network du jour. How can I automatize that?
It just downed on me that smartphones don't need explicit APN entry to work when changing the sim card (also, the APN is sometimes different in M2M and actual cell phone, not sure I can use the same trick).
(I know you are curious: it's deployed in the middle of nowhere, and we chose the least worst network at the last minute on the installation site)
You can detect the network operator from the IMSI of the SIM, and have in your device a table mapping operators to APNs.
There are several sites that will provide you an IMSI to operator listing or MCC and MNC to operator listing. The MCC (Mobile Country One) is the first three digits of the IMIS and the MNC (Mobile Network code) the next 2 or 3 digits. Some example links:
https://www.imei.info/carriers/
https://www.mcc-mnc.com
As an aside, if you want to be able to change to adapt to the best available network coverage over time, the way many M2M applications achieve this is to use a 'forgein' SIM which can then roam to the best available signal at a given time. If your data usage requirements are low this can be a good way to avoid being dependent on one operator in an area with poor coverage. There are quite a few companies who specialise in these type of M2M sims, depending on your target location.
Related
Carrier aggregation combines the existing spectrum, say if the carrier had previously 20MHz in the area, with the newly acquired spectrum of 20MHz, to give a wider pipe or bandwidth for data flow between the mobile device & the base station tower.
My question is, why don't they just operate the new bandwidth as a separate pipe? So that there would be two pipes of 20MHz each, instead of one aggregated pipe of 40MHz?
Benefits:
Carriers won't have to deal with the complexity of Carrier Aggregation technology, as the two bands are totally separate (2300MHz & 1800MHz). End-users can be divided over the two frequencies. Theoretically this should halve the load on one channel, providing double the speeds to connected users.
Many existing 4G devices use single antenna for 4G operation. The LTE-A tech needs MIMO support on both mobile & tower to work. Essentially it needs 2 antennas on both mobile & tower for operating 2 different frequencies, which only stresses the mobile device. Existing hardware cannot benefit from LTE-A, where speeds will continue to remain the same post upgradation. In fact, it may slightly decrease post LTE-A implementation, since newer LTE-A devices will share load on both the frequencies, but existing LTE users can only use one.
For those new, this simple image explains how Carrier Aggregation works. https://www.techtalkthai.com/wp-content/uploads/2014/12/qualcomm_carrier_aggregation.jpg
1) Assuming that the operator already has 2 bands, it is really not complex to enable and configure carrier aggregation. It is likely that they already have the ability as part of the latest LTE software upgrades and it is just a matter of configuring it and possibly paying for a license to use it.
The scenario you describe of using two separate pipes instead of a single CA pipe is not feasible (or may not be possible?). When a device establishes a connection in an LTE network, a default bearer is configured which would not be able to simultaneously use two radio connections without CA or other similar features. Multiple bearers can certainly be established simultaneously, however they serve different purposes (e.g. voice vs data). That said, really CA is using two different pipes, but they act as a single (logical) bearer. Another advantage of CA is that the control plane signaling takes place on only one of the component carriers and therefore the other component carriers can be fully dedicated to user plane traffic.
2) I'll clear a few things up:
MIMO has nothing to do with Carrier Aggregation.
Most 4G devices today transmit on a single antenna and receive on two antennas. (Although they most likely have at least 2 tx and 2 rx antennas, and many have 4 tx and 4 rx antennas, although 4x4 MIMO has not been implemented by most operators.)
Existing devices are already taking advantage of LTE-A features and some operators are currently rolling out 3-carrier CA, 4x4 MIMO as well as 256QAM.
Here is a recent news article which discusses LTE-A features which have already been implemented: https://newsroom.t-mobile.com/news-and-blogs/lte-advanced.htm
I have written and simulated a Verilog code in ISE Project Navigator 2013. this is an RTL model that describes the network-on-chip routers, buffers and links.
which device is better for synthesis and implementation?
How can I get the static and dynamic power consumption, a packet transfer delay, area and the other factors that indicates network performance, using ISE Project Navigator?
The question is very open ended so I will try to provide as general an answer as possible.
Now you have said that you have the code for a NOC Router in ISE. This would imply that you or the designer has a rough idea of the frequency at which the internal logic/system has to operate. The maximum clock tree frequency of your target device and would then be one of the key parameters that you need to check. If your design is running at around 150-200 MHz and is appropriately pipelined (small muxes, not more than 2-3 levels of logic between pipelining stages), then almost any of the currently available device families from both Xilinx and Altera should be suitable.
The next important consideration is of external connectivity. Does your design need high-speed serial connectivity with an external device. If that is true, then you would need to select a device that has high-speed SERDES IPs in-built. That would then limit your choice of devices.
Another factor to consider is interface to external SDRAM or RLDRAM. If your design needs to interface with such external devices, then you need to pick a device that has support either through a softcore or a Megafunction (Altera) or a hard IP block.
Finally you need to look at your logic utilization. You want to chose a device that is just big enough to satisfy your requirements, unless your design is part of a bigger project and there are modules that would be designed later and would sit alongside your NOC. You would have to make a rough guess of the number of LEs/LUTs that your design would need and pick a device 50% bigger than that. You can then run a trial synthesis run and check if your estimates are okay. If they are, and your device is less than 50% utilized, you could go in to a smaller device as need be.
There are also a few other considerations such as number of IOs, presence of a PLL/Clock manager that may affect your choice of device
My question is more specific to GSM mobile telephony networks and more or less about SS7/SigTran Protocol suite. So I am not asking the possibility of knowing SIM card details using IMEI number from an end user point of view as it is asked here.
Being a network operator is there anyway that I can retrieve the IMSI associated with IMEI number from MSC,VLR, HLR or any other network elements in the core network(I am excluding EIR on purpose as my current implementation does not include that)? The query should be just based on IMEI with an assumption that we are not interacting with the SIM or the device. Do any of these elements store IMEI-IMSI pair when it is used before.
In summary is it possible to retrieve IMSI from the database of any of the network elements provided just IMEI number. If yes, how? what are the messages (e.g. provideSubscriberInfo-req) that are needed and the ASN1 encoding scheme.
P.S: This is not handset specific such as the one mentioned here , more of network operator specific.
Well its not possible(not that I know off) from a standard GSM operation where you can input IMEI and receive IMSI. However you can get IMSI if you know the MSISDN by GSM Map operation Any_Time_Interrogation_Request. We are using a solution from sigtrangateway.com SigtranGateway.com for same purpose in a telco project and its working fine so far.
I have a small project (for my cell phone) on the go, and I believe I have found IO Control codes for what I want to accomplish (theres nothing at a higher level unless I can reverse engineer the dlls and call them).
However, the codes are from a different device from a different manufacturer (the board is the same - a snapdragon 8650)
Will those control codes be likely to work on my device, or is that going to be dependent on something manufacturer specific?
Am I likely to be able to do permanent damage to my phone by trying them?
The answer itself is manufacturer-dependent.
Having the same board, chances are at least some of the codes are the same.
And the likelihood of causing damage is low (unless you hit FLASH memory).
I'd give it a go, if it were my phone.
what is the relation between BTS and cell? I think one BTS hardware can cover few cells and also some cells could be covered by more than one BTS isn't it?
Is part of information, that mobile receives from GSM network identification of concrete BTS or mobile phone knows only cell-id?
Is part of information, that mobile receives from GSM network identification of BSC?
Ad 1: Typically one BTS can handle several cells. Common patterns are a one BTS covering a circular area with one round-radiating antenna or a three-sector BTS which covers three cells with sector-radiating antennas. One cell can only be handed by one BTS at a time. Two or more BTSes are not possible since the radio communication would interfere with each other. Note that this is completely different in WCDMA/UMTS since there is no concept of cells.
Ad 2: Since one cell is covered by exactly one BTS, the cell id uniquely identified the concrete BTS.
Ad 3: Since the BTS does not contain any control logic, the mobile communicates directly with the BSC, e.g. about radio resources.
Edit after comment:
1/ The BTS is "dumb" to say it simply. It does only what the BSC instructs it to do. E.g. The BSC tells the BTS as well as the mobile which frequencies to use for the radio communication. A BTS does not route traffic as it is hooked to exactly one BSC. It even does not route traffic to one of several mobiles attached to the BTS as this is done by the BSC. Think of the BTS as a Um-to-Abis physical layer and protocol transcoder.
2/ Actually my earlier statement that UMTS has no cell concept is not exactly true, it's just different.
GSM is FTDMA (frequency and time division multiple access). The radio channel is shared by using different frequecies (per cell) and timeslots (per mobile). Since radio frequency is used to distinguish participants, great care must be taken that not two GSM participants use the same frequency at the same time at the same location. The solution to this is cells, where geographic areas have different frequencies assigned. Network planning must ensure that no two neighbouring cells use the same frequencies as this may lead to interference since you cannot control exactly the size of a cell (e.g. due to absorption and reflection). In GSM, a BTS has a fixed number of radio transmission channels, the number depends on the BTS hardware configuration. If all channels are in use, the cell is full, this is indpendent of the location of a mobile in the cell.
UMTS is CDMA (code division multiple access). The radio channel is shared by encoding the payload in a way that allows to decode it later even if several senders use the same frequency range. That requires coding schemes which are collision free (all codes are different from each other to avoid senders using too similar codes) and a great deal of signal processing. As an analogy: on a party you can understand someone accross the room, even if ten people are talking. The more senders communicate within the cell, the smaller the cell gets in order to allow the BTS/Node-B distinguishing between senders. Therefore, in UMTS a cell size is not geographically fixed. The cell "breathes" depending on its load.
OK, this thread is quite old, but requires some further clarifications for next generations.
When talking about GSM physical network architecture, the term BTS (Base Transceiver System) refers to the physical site itself - the 'small house with the tower' (although modern small BTSs are just boxes hanged on walls or placed on roof tops).
Each such physical site can host one omni-directional cell, or several sector cells.
In GSM logical network architecture, there is some confusion.
The terms 'Cell' and 'Base Station' actually refer to the same physical entity (a set of transceiver units, each used to receive and transmit one of the paired UL/DL carrier frequencies allocated in the BA frequency set). Let's call this entity 'physical cell' just for clarification.
The term Base Station is used for radio resource management. A BSIC (BS Id Code, or BTS Id Code) is allocated for the 'physical cell' and is used in the radio-related conversations between the MS (Mobile Station) and the BSS (BTS and BSC), e.g. for measurement reports.
The BSIC is composed of 'local' parameters - Network Color Code (NCC) and BS Color Code (BCC), and is therefore unknown outside the network.
This is where the term Cell comes in:
The term Cell is used for Mobility Management. A Cell Identity (CI) is defined as a refinement of the Routing Area - one RA will include several cells in it.
The Global Cell Identifier (GCI) is composed of network, RA and CI, and is used for handovers inside and outside the network.
It is up to the BSC to convert the BSIC to the Cell Identity (the BSC may convert the BSIC directly to GCI, or the BSC converts to CI, and the MSC will convert it to GCI).
Hope that helps a bit.
BTS means different at different place！
MS, BTS, BSC, when these words appear together, BTS means something between your phone and the MSC.
Sometimes we call a site (a small house and a tower) as a BTS.
In NOKIA gsm equipment，cell is called segment. Every cell has at least one BTS，different BTS has different functions，Eg：BTS1 provide voice service，BTS2 provide EDGE service。
Phone get BCCH(freq)/NCC/BCC to identificate different cells. Decode the information from BCCH to get CI, LAC...etc.