General packet Radio Service (GPRS) is a enhancement of GPS, which is packet oriented mobile data service on the 2G and 3G cellular communication system. It provide connection to the external packet data network through the GSM infrastructure with short access time to the network for independent short packets. It uses exactly uses the same physical radio channel as GSM and only new logical GPRS Radio Channel are defined. GPRS was originally standardized by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD & i-mode packet-switched cellular technologies. Here in this post, GPRS Architecture in Mobile Communication is explained in detail.
GPRS Network Architecture:
GPRS is usually attempts to reuse the existing GSM network elements as much as possible. There are new entities called GPRS that supports nodes (GSN) which are responsible for delivery and routing of data packets between mobile stations and external packets networks. There are two types of GSNs,
- Serving GPRS Support Node (SGNS)
- Gateway GPRS Support Node (GGNS)
These two modesare comparable to MD-IS in CPDP. There is also a new database called GPRS register which is located with HLR. It stores routing informations and maps the IMSI to a PDN address. Thus, GPRS Reference Architecture is shown as-
Subsystems of GPRS Architecture
GPRS Services required New Mobile Station as the existing GSM phones are not capable of handling the enhanced air interface or the packet data. A wide variety of Mobile stations exist which includes a high-speed version of current phones to support high-speed data access like PC cards for laptop computers. These mobile stations are in backward compatibility mode in order to make voice calls which are used GSM.
Base Station Subsystem:
Each BSC requires the installation of Packet Control Units in addition to software upgrade. They provide physical and logical data interface to BSS to estimate packet data traffic. BTS too require a software upgrade but typically does not involve hardware enhancements.
When the traffic is originated at the subscriber mobile then it is transported over the air interface to BTS and then from BTS to BSC, the same way in standard GSM call. But at output of BSC the traffic is separated, the voice is sent to the mobile switching centre per standard GSM and the data is sent to the new device called the SGSN via the PCU.
GRPS Support Nodes:
- SSGN: The Serving GPRS Support Node is responsible for authentication of GPRS mobiles, registration of mobiles in the network, mobility management, and collecting information for charging for the use of the air interface.
- GGSN: The Gateway GPRS Support Node acts as an interface and a router to external networks. The GGSN contains routing information for GPRS mobiles, which is used to tunnel packets through the IP based internal backbone to the correct Serving GPRS Support Node.
Internal Back Network:
The internal backbone is an IP based network which is used to carry the new packets between different GSN. The process of Tunneling is used in-between SGSNs and GGSNs, this is done to safe exchange of domain informations outside the GPRS Network with out informing internal backbone.
In a manner similar to GSM and CDPD, there are mechanism in GPRS to support mobility. There are two types of Mobility Support in GPRS Network-
- Attachment Procedure
- Location and Handoff Management
Short Messaging Services in GSM:
For the proliferation of GSM enable the introduction of SMS, which is similar to peer-to-peer instant messaging on the Internet. Users of SMS can exchange alphanumeric message of up to 160 char. with in seconds of submission of the message.
- Wireless Communication Concepts
- Principles of Communication
- Wireless Communication System and the Technical Challenges
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