Understanding GSM MAP Anytime Interrogation (ATI)

With MAP ATI, the Service Control Point (SCP) will send a MAP Any Time Interrogation (ATI) message to the HLR requesting location information.  The HLR will in turn query the appropriate MSC (shown here as a SSP) to perform a VLR look-up.

The MAP ATI query comes from the Location Management Function (LMF), which may or may not be a traditional SCP.  One of the key things to note about MAP ATI is that is does not always provide the most current Cell ID, but always provides the accurate Location Area.

GSM_MAP_ATI

GSM MAP ATI

While the MAP ATI is advantageous regarding no need for GPS on the hand-set and no need for other potentially expensive positioning solutions such as T-DOA, it is disadvantageous from a network management perspective.   The HLR is the heart of the mobile operator network and is capacity sensitive.  Therefore, most network planners do not allow access to the HLR or “pinging” it, on any scale, let alone for LBS applications that may scale to cause many queries per second.

For more information, see: http://www.mindcommerce.com/

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Analysis of telecom and ICT infrastructure, technologies, and applications.
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4 Responses to Understanding GSM MAP Anytime Interrogation (ATI)

  1. Jee Loo says:

    “One of the key things to note about MAP ATI is that is does not always provide the most current Cell ID, but always provides the accurate Location Area.” — Doh, I wasn’t aware of that. Under which conditions does it happen that a cell other than the current one is returned?

    Thank you!
    Jee Loo

    • Mind Commerce says:

      The issue is that the VLR knows what Cell ID the BS enters into the LA, but does not track every Cell ID within the LA as the BS moves. Therefore, if the BS comes into a LA, and never moves (to another Cell ID), it knows with 100% accuracy, but BS’s move, so the reality is that one cannot be sure what Cell ID is actual one (based on query to VLR alone)

  2. Victor Sandoval says:

    Mind Commerce, in the context of your response I think you mean to say, MS (mobile station) enters the LA and moves or stays in a particular cell.

  3. Billy Lau says:

    if you want to know the subscribers status, some information must add-in to the ATI
    Location information
    1. Subscriber State (will triiger Paging subscriber, then you know the Cell ID)
    2. Current Location (this is a must parameter).

    Then PSI will go to MSC/SGSN/MME for retrieve subscriber information . and it return to HSS.
    Try to use Application Context Version V3 to sending ATI. You can get cell id of the subscriber.

    Remark:
    ATI can choose to query which domain (CS, PS)

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