SUPL (secure user-plane location)

SUPL, which stands for Secure User-Plane Location, is a protocol designed to enable accurate and secure location determination in mobile devices. SUPL is specifically focused on providing location-based services (LBS) in cellular networks, allowing mobile operators and service providers to deliver location-based applications and services to their subscribers.

The primary goal of SUPL is to establish a secure and efficient communication channel between the user equipment (UE), such as a mobile phone, and the location server (LS) responsible for providing the location information. This communication channel ensures the privacy and integrity of location data while enabling accurate positioning.

To achieve secure user-plane location determination, SUPL operates in conjunction with other existing protocols and technologies, including the Global Positioning System (GPS), cellular networks (such as GSM, UMTS, or LTE), and the Internet Protocol (IP) suite.

Here is a detailed explanation of the components and workings of SUPL:

1. User Equipment (UE): The UE refers to the mobile device or terminal, such as a smartphone or tablet, that seeks location-based services. The UE communicates with the SUPL-enabled network to request and receive location information.
2. Secure User-Plane Location (SUPL) Protocol: The SUPL protocol defines the communication mechanisms and procedures between the UE and the location server (LS). It operates over the user plane of the cellular network, leveraging existing data bearers such as General Packet Radio Service (GPRS) or Enhanced Data rates for GSM Evolution (EDGE) in GSM networks, or packet-switched connections in UMTS and LTE networks.
3. Location Server (LS): The LS is responsible for managing and providing location information to the UE. It receives location requests from the UE via the SUPL protocol and retrieves the necessary location data. The LS can be operated by the mobile network operator or a third-party location service provider.
4. Positioning Method: SUPL supports various positioning methods, including GPS, Assisted GPS (A-GPS), Cell ID, and Enhanced Cell ID. These methods enable the LS to determine the location of the UE based on satellite signals, cell tower information, or a combination of both. The LS selects the most appropriate positioning method based on factors like accuracy requirements, available network resources, and UE capabilities.
5. Secure Channel Establishment: SUPL ensures the establishment of a secure communication channel between the UE and the LS. This is achieved through the use of Transport Layer Security (TLS) or Secure Real-Time Transport Protocol (SRTP) to encrypt and authenticate the data exchanged between the UE and the LS. The secure channel protects against unauthorized access, eavesdropping, and tampering of location data.
6. Privacy Protection: SUPL incorporates mechanisms to protect the privacy of the UE. It ensures that location information is only shared with authorized parties and that the user's consent is obtained before disclosing location data. SUPL also allows users to control their location privacy preferences, such as specifying when and how their location information can be accessed.
7. Protocol Interworking: SUPL supports interoperability between different network technologies and protocols. It enables seamless integration of location determination capabilities across various cellular networks, including GSM, UMTS, and LTE. This allows location-based services to be delivered consistently to mobile subscribers regardless of the underlying network infrastructure.
8. Network Assisted and Network Based Positioning: SUPL supports both network-assisted and network-based positioning methods. Network-assisted positioning involves the UE collecting data from the network (e.g., satellite ephemeris, reference time, or signal measurements) to aid in the satellite-based positioning process. Network-based positioning relies solely on network measurements without direct satellite involvement.

By leveraging the capabilities of SUPL, mobile network operators and service providers can offer a wide range of location-based services to their subscribers. These services include emergency call positioning, vehicle tracking, mobile advertising, navigation and mapping applications, and social networking applications that rely on location information.

In summary, SUPL (Secure User-Plane Location) is a protocol that facilitates secure and accurate location determination in mobile devices. It establishes a secure communication channel between the UE and the LS, ensures privacy protection, supports various positioning methods, and enables interoperability across different network technologies. SUPL plays a crucial role in enabling location-based services and enhancing the user experience in cellular networks.