GPRS Functional Architecture
GPRS uses the GSM architecture for voice.
Here, GPRS support nodes are responsible for the delivery and routing of data packets between the mobile stations and the external packet data networks (PDN).
There are 2 types of support nodes which are given below:
Serving GPRS Support Node (SGSN)
- An SGSN is at the same hierarchical level as the MSC. Whatever functions MSC does for the voice, SGSN does the same for packet data.
- Moreover, SGSN’s tasks include packet switching, routing and transfer, mobility management, logical link management, and authentication and charging functions.
- SGSN processes the registration of new mobile subscribers and keeps a record of their location inside a given service area.
- Moreover, The location register of the SGSN stores location information and user profiles of all GPRS users registered with the SGSN.
- SGSN sends queries to HLR to obtain profile data of GPRS subscribers. The SGSN is connected to the base station system with Frame Relay.
Gateway GPRS Support Node (GGSN)
- A GGSN acts as an interface between the GPRS backbone network and the external packet data network.
- Moreover, GGSN’s function is similar to that of a router in a LAN. GGSN maintains routing information that is necessary to tunnel the Protocol Data Units (PDUs) to the SGSNs that service particular mobile stations.
- It converts the GPRS packets coming from the SGSN into the appropriate packet data protocol (PDP) format for the data networks like internet or X.25, PDP sends these packets out on the corresponding packet data network.
- The readdressed packets are sent to the responsible SGSN. For this purpose, the GGSN stores the current SGSN address of the user and his or her profile in its location register.
- Moreover, GGSN also performs authentication and charging functions related to data transfer.
- Some existing GSM network elements must be enhanced in order to support packet data. These are as following:
AUC Authentication Center
- MS Mobile Station
BSC Base Station Controller
- MSC Mobile Switching Center
BTS Base Transceiver Station
- PDN Packet Data Network
EIR Equipment Identity Register
- PLMN Public Land Mobile Network
- GGSN Gateway GPRS Support Node
- SMSC Short Message Service Center
GPRS General Packet Radio Service
- SMS-GMSC SMS Gateway MSC
HLR Home Location Register
- SMS-IWMSC SMS Inter-Working MSC
ISDN Integrated System Digital Network
- SGSN Serving GPRS Support Node
Base Station System (BSS)
- BSS system needs enhancements to recognize and send packet data.
- Moreover, This includes BTS upgrade to allow transportation of user data to the SGSN.
- Also, the BTS needs to be upgraded to support packet data transportation between the BTS and the MS (Mobile Station) over the radio.
Home Location Register (HLR): GPRS functional architecture
- HLR needs enhancement to register GPRS user profiles. And Also, respond to queries originating from GSNs regarding these profiles.
Mobile Station (MS) GPRS functional architecture
- The mobile station or the mobile phone for GPRS is different from that of GSM.
- SMS-GMSCs and SMS-IWMSCs upgraded to support SMS transmission via the SGSN.0
- Optionally, the MSC/VLR can enhance for more efficient coordination of GPRS and non-GPRS services and functionality.
- Moreover, GPRS uses two frequency bands at 45 MHz apart; viz., 890-915 MHz for uplink (MS to BTS), and 935-960 MHz for downlink (BTS to MS).
Applications of GPRS
- Communications: E-mail, fax, unified messaging and intranet/internet access, etc.
- Value-added services: Information services and games, etc.
- E-commerce: Retail, ticket purchasing, banking and financial trading, etc.
- Location-based applications: Navigation, traffic conditions, airline/rail schedules and location finder, etc.
- Vertical applications: Freight delivery, fleet management, and sales-force automation.
- Advertising: It may be location sensitive. For example, a user entering a mall can receive advertisements specific to the stores in that mall.