Gprs architecture is also known as the 2.5G technology, or between the 2G technology and the 3G technology. The 2G technology is the GSM architecture and the 3G technology is the UMTS architecture, when we talk about GPRS architecture technology we are more talking about the mix of 2G and 3G.
So, 2G architecture is completely circuit switched service which means the transmission of your voice calls has to be taken by the continuous data streams originating from the sender and aiming at the receiver. When the connection is established for the sender and receiver, the data stream flows and therefore they reserve some space in the transmission bandwidth so the voice signal keeps on flowing without any breaks.
Also,3G architecture is a pure packet switching service. The packet switching service refers to the transfer of the data in form of data packets. When any email is send from the sender location to the receiver location the message is divided into various data packets, these data packets have the location of both the sender and the receiver, the sender location helps the data packet to get back to the place of origin if you don’t found out the source or any other errors that may occur. Also, the packet switching service also helps to increase the efficiency for using the resources of the network, it doesn’t reserve the complete bandwidth as in the case with the circuit switching service. Also the voice transmission occurs with the help of VoIP or Voice over IP in the 3G technology which is usage of the data packets for the voice signals.
The GPRS architecture is built on the GSM architecture. It was built to provide the data service to the users of the internet, so the GPRS was the solution. The GSM architecture is designed for the voice transmission but no internet connection, the GPRS architecture introduced two nodes for this and one is the SGSN and other is the GGSN, these two support structure is what allowed the GSM architecture user to access internet and open web pages on their mobile device.
The GPRS architecture consists of all the elements that make up the GSM architecture, in addition to the PCU (packet control unit), SGSN ( serving GPRS support node), and GGSN ( gateway GPRS support node). Let’s see each of them.
Packet Control Unit
The PCU is a late addition to the GSM architecture which involves data processing, the PCU work is to identify the type of the data whether it is data packet or analog voice signals and then send them respectively to the appropriate switching service that is either packet switching circuit or the circuit switching circuit from. When the switching circuits are decided by the PCU it is then transferred to the GSM network for the voice signal or the GPRS network for the data packet.
Serving GPRS Support node
The next we are going to see is the SGSN or the Serving GPRS Support node. The SGSN can be referred to as MSC of the GPRS architecture, the SGSN has to route the data packet in the complete architecture and the packets then reach to the GGSN where the connection to the Internet providers or the servers of the companies are theirs. Along with the routing of the data packets, as the work of the MSC also included the mobility management so does the SGSN. The SGSN takes care when the user moves from one area to another area the connection of their mobile network is maintained to the particular area SGSN. Now the other important function of the SGSN is to use the unique key to confirm the subscription of the various services to which the user has subscribed, so that authentication can take place and the user is able to continue to their respective services if they move from one area to another.
Gateway GPRS Support Network
GGSN or the Gateway GPRS Support Network are like the anchor points in the GPRS architecture and data packets move from the mobile devices to the SGSN and then when the validity of the user is checked and the routing path has been decided and if the path does not lie in the local SGSN area then GGSN has to be contacted to find the correct address in the external SGSN and then route the packets to them. GGSN is like a router to an IP sub network, when the GGSN receive the data address to the specific user then it performs a check whether the user is active in the sub network for routing the data, if the user is active the GGSN will route the data to the specific address to the user and if not active the GGSN will route the data packet back to the source or keep in the buffer depending on the activity of the user.
Also, the three additional units that we have discussed so far are the units which lay with the GSM architecture. Now with addition to the new units other units in the GSM architecture have to be upgraded depending on the change of technology such as hardware and the software. The hardware of the mobile equipment has to be upgraded to support the data packet transmission as earlier it supported only the voice signal now with the introduction to the internet the new technology has to be embedded into the mobile devices. The hardware changes have to be done in the BSC as well as some software changes to support the data packet transfer but no hardware upgradation to the MSC as its purpose is to control the BSC and route the voice signals therefore only software upgrades were done in the MSC.