About GPRS wireless technologies:
GPRS stands for (General Packet Radio Serviceis) a type of wireless data
connection. It is a second generation (2G) and third generation (3G)--or
sometimes refered to as in-between both generations, 2.5G--wireless data service
that extends GSM data capabilities for Internet access, multimedia messaging
services(mms), and early mobile Internet applications via the wireless
application protocol (WAP), as well as other wireless data services.
Key Features of GPRS:
Speed: One of the headline benefits of GPRS
technology is that it offers a much higher data rate than was possible with GSM.
Rates up to 172 kbps are possible, although the maximum data rates realistically
achievable under most conditions will be in the range 15 - 40 kbps.
GPRS wireless networks were later enhance faster 3G (third generation)
throughput speeds. T-Mobile's EDGE (enhanced Data Rates for Global Evolution),
for example, delivers up to 4 times the GPRS rate.
Both GPRS and Edge, however, are quickly being surpassed by even faster
4G (fourth generation) mobile data networks.
Packet switched operation:
Unlike GSM which was used circuit switched techniques, GPRS technology uses
packet switching in line with the Internet. This makes far more efficient use of
the available capacity, and it allows greater commonality with Internet
techniques.
Always on connectivity:
A further advantage of GPRS is that it offers an "Always On" capability. When
using circuit switched techniques, charges are based on the time a circuit is
used, i.e. how long the call is. For packet switched technology charges are for
the amount of data carried as this is what uses the services provider's
capacity. Accordingly, always on connectivity is possible.
More applications:
The packet switched technology including the always on connectivity combined
with the higher data rates opens up many more possibilities for new
applications. One of the chief growth areas that arose from GPRS was the
Blackberry form of mobile or PDA. This provided for remote email applications
along with web browsing, etc.
Access technologies:
GPRS was one of the earliest cell phone data access technologies, and
more widespread particularly in Europe and Asia, though it was adopted by
carriers in North America, such as Rogers in Canada and T-Mobile in the US.
Data
rates:
2G (second generation) GPRS service had data rates of 56-114 kbit/second--akin
to dial-up modem speeds.
Network Protocols Used in GPRS :
There are several protocols used in the network equipment. These protocols
operate in both the data and signalling planes.
The following is a brief description of each protocol layer:
| protocol layer | Description |
Sub-Network Dependent Convergence Protocol (SNDCP): |
the protocol that maps a network-level protocol, such as IP or X.25, to the underlying logical link control. SNDCP also provides other functions such as compression, segmentation and multiplexing of network-layer messages to a single virtual connection. |
| Logical Link Control (LLC): | a data link layer protocol for GPRS which functions similar to Link Access Protocol - D (LAPD). This layer assures the reliable transfer of user data across a wireless network. |
| Base Station System GPRS Protocol (BSSGP): | BSSGP processes routing and quality of service (QoS) information for the BSS. BSSGP uses the Frame Relay Q.922 core protocol as its transport mechanism. |
| GPRS Tunnel Protocol (GTP): | protocol that tunnels the protocol data units through the IP backbone by adding routing information. GTP operates on top of TCP/UDP over IP. |
| GPRS Mobility Management (GMM): | protocol that operates in the signalling plane of GPRS and handles mobility issues such as roaming, authentication, and selection of encryption algorithms. |
| Network Service: | protocol that manages the convergence sub-layer that operates between BSSGP and the Frame Relay Q.922 Core by mapping BSSGP's service requests to the appropriate Frame Relay services. |
| BSSAP+: | protocol that manages paging for voice and data connections and optimizes paging for mobile subscribers. BSSAP+ is also responsible for location and routing updates as well as mobile station alerting |
Security:
GPRS security functionality is equivalent to the existing GSM security.
The SGSN performs authentication and cipher setting procedures based on the same
algorithms, keys, and criteria as in existing GSM. GPRS uses a ciphering
algorithm optimised for packet data transmission.
Examples:
GPRS, which refers to a mobile or wireless data service, is not the same as
GPS, which refers to geo-location. GPRS data networks enable users to access
Web data and rich content from their cell phones.