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MAP (Mobile Application Part)

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The Mobile Application Part (MAP) is a protocol used in the telecommunication network that connects Mobile Switching Centers (MSC) and Home Location Registers (HLR) in a GSM/UMTS/LTE network. MAP is responsible for providing signaling support for various applications that are used in mobile communication such as SMS, location-based services, and voice call services.

The MAP protocol is part of the SS7 protocol stack and is used for communication between the MSC and the HLR. The MSC is responsible for handling the voice and data communication for a mobile subscriber while the HLR is a database that stores information about the subscriber, including their location, billing information, and service profiles. The MAP protocol allows these two network elements to communicate with each other to ensure that the subscriber can receive and make calls, and that their location information is accurately maintained.

In this article, we will discuss the architecture, features, and functions of the MAP protocol, as well as its role in providing various mobile services.

MAP Architecture

The MAP protocol is a layered architecture that comprises three layers: the MAP user layer, the MAP service layer, and the MAP transport layer. Each layer is responsible for specific tasks, as shown in the figure below:

  1. MAP User Layer: The MAP user layer is the topmost layer in the MAP architecture and is responsible for providing the interface between the MAP protocol and the applications that use it. The MAP user layer communicates with the MAP service layer to initiate or terminate MAP signaling messages.
  2. MAP Service Layer: The MAP service layer is the middle layer of the MAP architecture and is responsible for providing the actual services that use MAP signaling. The MAP service layer communicates with the MAP transport layer to send and receive MAP messages. The MAP service layer includes various services such as SMS, Location-Based Services (LBS), Call Control, and Roaming.
  3. MAP Transport Layer: The MAP transport layer is the lowest layer in the MAP architecture and is responsible for providing the transport mechanism for MAP messages between the MSC and the HLR. The MAP transport layer uses the SS7 protocol stack to transmit MAP messages over the Signaling Transfer Point (STP) in the SS7 network.

MAP Features and Functions

The MAP protocol provides several features and functions that enable the provision of various mobile services. Some of the key features and functions of MAP are discussed below:

  1. Call Control: MAP enables call control functions such as call setup, call routing, and call teardown. The MAP protocol provides signaling messages for call establishment, which include location updates, subscriber authentication, and call routing.
  2. Short Message Service (SMS): MAP provides signaling support for SMS messages, including SMS transmission, delivery, and acknowledgement. The MAP protocol allows the MSC and HLR to communicate with each other to ensure that the SMS messages are delivered to the intended recipient.
  3. Location-Based Services (LBS): MAP enables location-based services such as Mobile Location Center (MLC) and Gateway Mobile Location Center (GMLC). The MLC and GMLC are responsible for providing location information about a subscriber to other network elements, such as applications or emergency services.
  4. Roaming: MAP enables roaming services by allowing the MSC to communicate with the HLR of a visiting network. The MSC sends a request to the visited HLR to obtain information about the subscriber, including their location and service profile. The visited HLR then provides this information to the MSC, enabling the subscriber to use their mobile services in the visited network.
  5. Authentication and Authorization: MAP provides signaling messages for subscriber authentication and authorization. The MAP protocol uses the Authentication Center (AuC) to authenticate the subscriber and the Home Subscriber Server (HSS) to authorize the subscriber's access to network services. The MSC sends a request to the HLR, which then forwards the request to the HSS to authorize the subscriber's access to specific network services.
  6. Subscriber Profile Management: MAP provides signaling messages for subscriber profile management, including subscriber registration, updating subscriber information, and deactivating subscriber accounts. The MSC sends a request to the HLR to register a new subscriber, update subscriber information, or deactivate a subscriber account.
  7. Number Portability: MAP provides signaling support for number portability, which enables subscribers to keep their existing phone numbers when switching network operators. The MSC sends a request to the Number Portability Database (NPDB) to obtain information about the subscriber's ported number.

MAP Protocol Messages

The MAP protocol uses various types of messages to facilitate communication between the MSC and the HLR. Some of the commonly used MAP messages are discussed below:

  1. Location Update Request: The MSC sends a location update request to the HLR to update the subscriber's location information.
  2. Authentication Request: The MSC sends an authentication request to the HLR to authenticate the subscriber.
  3. Call Setup Request: The MSC sends a call setup request to the HLR to initiate a call.
  4. SMS Delivery Request: The MSC sends an SMS delivery request to the HLR to deliver an SMS message to the subscriber.
  5. Subscriber Profile Update Request: The MSC sends a subscriber profile update request to the HLR to update the subscriber's profile information.
  6. Number Portability Query Request: The MSC sends a number portability query request to the NPDB to obtain information about the subscriber's ported number.

Conclusion

The Mobile Application Part (MAP) protocol is a critical component of the GSM/UMTS/LTE network architecture, providing signaling support for various mobile services such as SMS, location-based services, and voice call services. The MAP protocol enables communication between the Mobile Switching Center (MSC) and the Home Location Register (HLR) to ensure that the subscriber can receive and make calls and that their location information is accurately maintained. The MAP protocol provides several features and functions, including call control, SMS, location-based services, roaming, authentication and authorization, subscriber profile management, and number portability. Overall, the MAP protocol plays a crucial role in ensuring the efficient and effective provision of mobile services in the telecommunication network.