General Packet Radio
Services (GPRS) is a packet-based wireless communication service
that promises data rates from 56 up to 114 Kbps and continuous
connection to the Internet for mobile phone and computer users. The
higher data rates allow users to take part in video conferences and interact
with multimedia Web sites and similar applications using
mobile handheld devices as well as notebook computers. GPRS is based
on Global System for Mobile (GSM) communication and complements existing
services such circuit-switched cellular phone connections and the
Short Message Service (SMS).
The figure below shows
how users can access internet through GPRS. One may use a mobile phone, PDA, or notebook to connect to a GPRS
network. A mobile phone can be use as a
modem to connect via GPRS.
General Packet Radio
Services may also be called 2.5G technology because it is an enchancement of
GSM (Global System for Mobile Communication) or TDMA (IS-136) network. It exist
in our cellular network infrastructure and enhances the technology by software
upgrades at the base station to create a GPRS gateway that connects to the
internet.
Because
GPRS is a packet switched network, a GPRS user station doesn't occupy a dedicated
path during an Internet connection. However, each end user station (e.g. mobile
phone) is allocated several time slots out of 8 GSM/TDMA available time-slots
for GPRS service. Each time slot has a maximum capacity of 14.4 kbps. Depending
on how many time slots are allocated for the downlink (from a base station to a
user station) and the uplink (from a user station to a base station), GPRS
devices are divided into multi-slot classes. A multi-slot class is often
represented by the number of downlink and uplink slots. For example, Class 10
is also known as Class 4+2. While active slots indicate the maximum number of
slots that can be allocated for both downlink and uplink in a specific class.
The following table lists available multi-slot classes.
With
GPRS, it will make mobile data faster, user-friendly and cheaper. It also
enables voice and data calls to be handled simultaneously. Instantaneous
connection setup is also achievable on mobile internet with high-speed internet
access. GPRS was
developed to enable GSM operators to meet the growing demands for wireless packet
data service that is a result of the explosive growth of the Internet and
corporate intranets. Another goal for GPRS is to enable GSM operators to enter
the wireless packet data market in a cost−efficient manner. First, they must be
able to provide data services without changing their entire infrastructure. The
initial GPRS standards make use of standard GSM radio systems. This also
includes GSM standard modulation schemes and TDMA framing structures. By doing
this, the cost implications are minimized in the cell equipment. Second, GSM
operators must have flexibility to deploy GPRS without having to commit their
entire network to it. GPRS provides the dynamic allocation and assignment of
radio channels to packet services according to the demand.
GPRS Public Land Mobile Networks
(PLMN) enables users to roam around within the geographic area and still
receive continuous transmission. Either way, the network tracks the location of
the MS so that incoming packets can be routed to the MS when they arrive. The
GPRS PLMN interfaces with the MSs via the air interface. GPRSs will initially
be provided using an enhanced version of the standard GSM interface. The end
user is able to access public servers such as web sites and private corporate
intranet servers. GPRS can also receive voice services via the GSM PLMN.
Advantages of
GPRS
GPRS brought mobile phone users out from the world of WAP, and
into a world where Internet was finally available on mobiles. This in itself
was a monumental feat, and hence GPRS took off with quite a bang. With GPRS,
large amounts of data can be transferred to and from the mobile device over the
Internet.
Disadvantages
of GPRS
Since GPRS uses the cellular network’s GSM band to transmit data,
more often than not, when a connection is active, calls and other
network-related functions cannot be used. The data session will go on standby.
This is a characteristic typical of the Class B GPRS device. There are Class A
devices as well, where there are two radios incorporated into the device,
allowing both features to run simultaneously. However, Class A devices tend to
be more expensive, and by extension, less popular. Most mobile phones fall in
the Class B category.
GPRS is usually billed per megabyte or kilobyte, depending on the
individual service provider. However, this has changed in many places, where
GPRS downloads are no longer charged as per usage, but are unlimited, and there
is merely a flat fee to be paid every month.
