General Packet Radio Service:
An In-Depth Introduction
Table of Contents
Roots of GPRS 9
Network/Industry Features 19
List of Figures
Roadmap of Data Services for GSM 9
Comparison of Data Transfer Speeds 10
GPRS History 11
GPRS Protocol Stack 16
GSM System Architecture 16
GPRS System Architecture 17
GPRS Contracts Awarded 21
Technical Feature Listing 24
Standard Library Functions 26
GPRS (General Packet Radio Service) is a step between GSM and 3G cellular
networks. GPRS offers faster data transmission via a GSM network within a
range 9.6Kbits to 115Kbits. This new technology makes it possible for users to
make telephone calls and transmit data at the same time. (For example, if you
have a mobile phone using GPRS, you will be able to simultaneously make calls
and receive e-mail massages.) This paper will entail an intermediate language
and serves to introduce this technology to both the developer and end-user alike.
I discuss the underlying architecture and basic functionality of GPRS followed by
its many applications.
The introduction of wireless communication has allowed many people
around the world to live their lives and conduct business in ways that were never
before possible. Millions of cellular subscribers have become accustomed to
always having a telephone with them wherever they go. Now, businesses are
wanting to be able to connect to the office when they are out of the office so they
can check their email, search on the Internet, access company files, send faxes
and data whenever and wherever it is needed. Currently, there are numerous
wireless data services available, but a new technology, General Packet Radio
Service, offers much excitement to consumers.
Primitive (2G) cellular data services do not fulfill the needs of users add
providers. From the user's point of view, data rates are too slow and the
connection setup takes too long and is rather complicated. Moreover, the service
is too expensive for most users. From the technical point of view, the drawback
results from the fact that current wireless data services are based on circuit
switched radio transmission.
Before introduction of GPRS, the radio capacity was used for calls and
data transmission within the GSM (Global System Mobile) network in a rather
inefficient way. For data transmission the entire channel was occupied and was
thus insufficiently used. With the GPRS technology, the channel is used more
efficiently owing to the possibility of more than one user sharing the same
channel. GPRS telephones user several channels for data transfer thus
facilitating greater transfer speeds. The GPRS infrastructure and mobile phones
support a data transmission speed of up to 13.4Kbits per channel.
I will treat GPRS from the point of view of GSM because GPRS is a new
bearer service for GSM that serves to improve and simplify wireless access to
packet data networks, e.g., to the Internet. It applies a packet radio principle to
transfer user data packets in an efficient way between GSM mobile stations and
external packet data networks. Packets can be directly routed from the GPRS
mobile stations to packet switched networks. Networks based on the Internet
Protocol (IP) (e.g. private/corporate intranets) and X.25 networks are supported
in the current version of GPRS.
Users of GPRS benefit from shorter access times and higher data rates. In
conventional GSM, the connection setup takes several seconds and rates for
data transmission are restricted to 9.6 kbit/s. Ideally, GPRS in practice offers
session setup times below one second In addition, GPRS packet transmission
offers a more user-friendly billing than that offered by circuit switched services. In
circuit switched services, billing is based on the duration of the connection. This
is unsuitable for applications with bursty traffic (e.g. Internet traffic). The user
must pay for the entire airtime, even for idle periods when no packets are sent
(e.g., while the user reads a Web page or email). In contrast to this, with packet
switched services, billing can be based on the amount of transmitted data. The
advantage for the user is that he or she can be "online" over a long period of time
but will be billed based on the transmitted data volume.
On this positive note let me present the General Packet Radio Service and its
significance in leading us to the modern 3G technologies.
GPRS makes sending and receiving small bursts of data, such as email
and web browsing, as well as large volumes of data over a mobile telephone
network possible. A simple way to understand packet switching is to relate it to a
jigsaw puzzle. Image how you buy a complete image or picture that has been
divided up into many pieces and then placed in a box. You purchase the puzzle
and reassemble it to form the original image. Before the information is sent, it is
split up into separate packets and it is then reassembled at the receivers end.
Some of the basic/prerequisite knowledge of GPRS follows.
-Due to the fact that more than one channel is used for downlink, the GPRS
mobile phones make possible greater data transmission speeds. There are
several types of phones with regard to the number of channels they use for data
• Type 2+1 – two downlink channels and one uplink data transmission
• Type 3+1 – three downlink channels and one uplink data transmission
• Type 4+1 – four downlink channels and one uplink data transmission
-The GPRS mobile phones can be classified into the following three classes
in terms of the possibility of simultaneous calls (via GSM) and data transmission
• Class A – Simultaneous calls (via GSM) and data transmission (via
• Class B – Automatic switching between the GSM and the GPRS mode is
possible according to telephone settings.
• Class C – Hand operated switching between the GSM and the GPRS
Data Transmission Speeds
-The supported data transmission speed per channel is 13.4Kbits. Depending
on the type of phone, the following data transmission speeds are theoretically
• Type 2+1: Receive 26.8Kbits and send 13.4Kbits.
• Type 3+1: Receive 40.2Kbits and send 13.4Kbits.
• Type 4+1: Receive 53.6Kbits and send 13.4Kbits.
In the core network, the existing MSCs (Mobile Services Switching
Centers) are based upon circuit-switched technology, and they cannot handle the
GPRS style packet traffic. Thus two new and very important components, called
GPRS Support Nodes, are added:
• Serving GPRS Support Node (SGSN)
• Gateway GPRS Support Node (GGSN)
The SGSN can be viewed as a "packet-switched MSC;" it delivers packets
to mobile stations (MSs) within its service area. SGSNs send queries to home
location registers (HLRs) to obtain profile data of GPRS subscribers. SGSNs
detect new GPRS MSs in a given service area, process registration of new
mobile subscribers, and keep a record of their location inside a given area.
Therefore, the SGSN performs mobility management functions such as mobile
subscriber attach/detach and location management.
GGSNs are used as interfaces to external IP networks such as the public
Internet, other mobile service providers' GPRS services. GGSNs maintain
routing information that is necessary to “tunnel” the protocol data units (PDUs) to
the SGSNs that service particular MSs. Other functions include network and
subscriber screening and address mapping, as well as authentication and
charging functions. One (or more) GGSNs may be provided to support multiple
SGSNs. More detailed technical descriptions of the SGSN and GGSN are
provided in a later section.
I would like to briefly mention GPRS security in order to “qualify” its
integrity. Its 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 optimized for packet data transmission.
-For more details on GSM security visit
Roots of GPRS
As I stated GPRS will complement rather than replace the current data services
available through today’s GSM digital cellular networks, such as Circuit Switched
Data and Short Message Service. It also provides the type of data capabilities
planned for “third generation” cellular networks, but years ahead of them. Figure
1 below is a timeframe of GSM data services and their availability.
Figure 1: Roadmap of Data Services for GSM
Timeframe Capabilities Notes
9.6 kbps service Available today Circuit-switched data Service available from
and fax most GSM operators
14.4 kbps service Available today Higher speed circuit- Works identically to
switched data and fax 9.6 kbps service only
at higher speed
Direct IP Access Available through Circuit-switched Reduces call set-up
some carriers today connection directly to time and provides a
Internet stepping-stone to
High-speed circuit- Available today High speed rates to 56 A software-only
switched data service kbps upgrade for carriers
(HSCSD) not requiring
GPRS Available today High speed packet Extremely capable and
data with transmission flexible mobile
speeds over 100 kbps, communications.
with most user
devices offering about
EDGE Available within three High speed packet Final high-speed data
years data which will triple technology for
the rates available existing networks.
Third generation Available within three High speed packet Completely new
cellular to five years data to 2 Mbps airlink.
Source: Paper: General Packet Radio Service (GPRS), September 30, 1998
According to the specifications provided by the European
Telecommunications Standards Institute (ETSI), the highest speed for a single
user session (or time slot) is the coding scheme CS4, which allows 21.4 kbps per
time slot. Thus, theoretically, a GPRS connection can provide a data
transmission speed of up to 171.2 Kbps (approximately three times that of a
fixed-line 56K dial-up) if all eight slots are used. GPRS’s rival, HSCSD, can
achieve up to 57.6 kbps. However, it is unlikely that network operators will let a
single user use up all the time slots. Even Nokia admitted that realistically GPRS
could achieve only about 43 Kbps while Ericsson thinks 56 Kbps is achievable.
Currently, GSM systems are running at 9.6 kilobits. A comparison of Data
Transfer Speeds (in kbps) follows in Figure 2.
Figure 2: A Comparison of Data Transfer Speeds (in Kbps)
56 K GSM HSCSD GPRS GPRS
Dial-Up (maximum speed) (maximum speed) (realistic speed)
56 9.6 57.6 171.2 43 to 56
Source: A CNET tutorial, July 2001.
GPRS could possibly be the technology that will allow consumers to really
begin to pursue the mobile Internet. GPRS is considered one step ahead of
HSCSD (High Speed Circuit Switched Data) and a step towards 3G (Third-
generation) networks. It is the step to 2.5G for GSM and TDMA (Time Division
Multiple Access) service providers.
GPRS is ideal for Wireless Application Protocol (WAP) services because
of the cost saving WAP over GPRS bring to mobile operators and cellular
consumers. Costs are reduced because GPRS radio resources are only needed
while the message is being transferred. For the end user, that means you only
pay for the time it takes to download the data and information that you need. For
the GSM operator, that means that you will be able to provide high speed
Internet access to consumers at a reasonable cost, because you will bill mobile
phone users for only the amount of data that they transfer rather than billing them
for the length of them that they are connected to the network.
With GPRS-enabled mobile phones, services are received faster than with
traditional GSM phones. GPRS offers an increase in data throughput rates, so
information retrieval and database access is faster, more usable and more
convenient. At its best, GPRS is transparent, allowing the user to concentrate on
the task in hand rather than on the technology.
Like the GSM standard itself, GPRS will be introduced in phases. Phase 1
became available commercially in the year 2000/2001. Point to Point GPRS,
which is sending information to a single GPRS user, was supported, but not Point
to Multipoint which is sending the same information to several GPRS users at the
same time. GPRS Phase 2 supports higher data rates through the possible
incorporation of techniques such as EDGE (Enhanced Data rates for GSM
Evolution), in addition to Point-to-Multipoint support. See Figure 3 below for a
timeline history of GPRS.
Figure 3: GPRS History
Throughout Network operators place trial and commercial contracts for GPRS
Incorporation of GPRS infrastructure into GSM networks.
Summer of 2000 First trial GPRS services become available.
Typical single user throughput is likely to be 28 kbps.
For example, T-Mobil is planning a GPRS trial at Expo2000 in
Hanover in the Summer of 2000.
Start of 2001 Basic GPRS capable terminals begin to be available in commercial
Throughout 2001 Network operators launch GPRS services commercially an roll out
Vertical market and executive GPRS early adopters begin using it
regularly for nonvoice mobile communications.
2001/2002 Typical single user throughput is likely to be 56 kbps.
New GPRS specific applications, higher bitrates, greater network
capacity solutions, more capable terminals become available, fueling
2002 Typical single user throughput is likely to be 112 kbps.
GPRS Phase 2/EDGE begins to emerge in practice.
2002 GPRS is routinely incorporated into GSM mobile phones and has
reached critical mass in terms of usage. (This is the equivalent to the
status of SMS in 1999)
2002/2003 3GSM arrives commercially.
Source: An Introduction to the General Packet Radio Service, January 2000
--Note: As we now get to a more technical portion it may be of value
to check the appendix for Technical features listings, as well as a
Glossary of terms/acronyms
LIMITED RADIO RESOURCES
There are only limited radio resources that can be deployed for different uses –
use for one purpose precludes simultaneous use for another. For example, voice
and GPRS calls both use the same network resources.
SPEEDS MUCH LOWER IN REALITY
Attaining the highest GPRS data transmission speed of 171.2 kbps would
require a single user taking over all eight timeslots; therefore, maximum GPRS
speeds should be compared against constraints in the GPRS terminals and
networks. It is highly unlikely that a GSM network operator would allow all
timeslots to be used by a single GPRS user. The initial GPRS terminals are
expected to only support one to three timeslots, which will be severely limiting to
users. The reality is that mobile networks are always likely to have lower data
transmission speeds than fixed networks. Mobile cellular subscribers often like to
jump on the fact that a certain technology has high data transmission speeds,
when the figure in all reality could be a theoretical number that is based on the
perfect situation. Consumers should, therefore, compare all available mobile
services and use the one that bests suits their needs.
NO SUPPORT OF MOBILE TERMINATED CALLS
There has been no confirmation by any mobile phone provider that initial
GPRS terminals will support mobile terminated GPRS calls (receipt of GPRS
calls on the mobile phone). When a mobile phone user initiates a GPRS session,
they are agreeing to pay for the content to be delivered by the GPRS service.
Internet sources originating unsolicited content may not be chargeable. A worse
case scenario would be that a mobile user would then be made responsible for
paying for the unsolicited junk content that they received. This is one main
reason why mobile vendors are not willing to support mobile terminated GPRS
calls in their terminals.
GPRS is based on a modulation technique known as Gaussian minimum-
shift keying (GMSK). EDGE is based on a new modulation scheme that allows a
much higher bit rate across the air interface – that is called eight-phase-shift
keying (8 PSK) modulation. Since 8 PSK will also be used for 3GSM, network
operators will need to incorporate it at some stage to make the transition to third
generation mobile phone systems.
GPRS packets are sent in many different directions to reach the same
destination. This makes room for the possibility for some of the packets to get
lost or damaged during the transmission over the radio link. The GPRS
standards are aware of this issue regarding wireless packet technologies and
have worked to integrate data integrity and retransmission approaches to solving
these problems. The result of this leads to possible transit delays.
NO STORE AND FORWARD
Currently, there is not a storage mechanism integrated into the GPRS
General Packet Radio Service comes to the market after High-speed
circuit-switched data service (HSCSD) is already in use as an update to the
services that it already offers. GPRS is a step in front of HSCSD and a step
closer to 3G. Not only will it increase data transmission speeds, but GPRS will
also offer the following user features and network features.
3 TO 10 TIMES THE SPEED
The maximum speed of 171.2 kbps, available through GPRS, is nearly three
times as fast as the data transmission speeds of fixed telecommunications
networks and ten times as fast as the current GSM network services.
INSTANT CONNECTIONS – IMMEDIATE TRANSFER OF DATA
GPRS allows for instant, continuous connections that will allow information
and data to be sent whenever and wherever it is needed. GPRS users are
considered to be always connected, with no dial-up needed. Immediacy is one of
the advantages of GPRS (and SMS) when compared to Circuit Switched Data.
High immediacy is a very important feature for time critical applications such as
remote credit card authorization where it would be unacceptable to keep the
customer waiting for even thirty extra seconds.
NEW AND BETTER APPLICATIONS
General Packet Radio Service offers many new applications that were
never before available to users because of the restrictions in speed and
messaged length. Some of the new applications that GPRS offers is the ability to
perform web browsing and to transfer files from the office or home and home
automation, which is the ability to use and control in-home appliances.
To use GPRS, the user will need:
• A subscription to a mobile telephone network that supports
GPRS – use of GPRS must be enabled for that user. Automatic
access to the GPRS may be allowed by some mobile network
operators, others will require a specific opt-in
• Knowledge of how to send and/or receive GPRS information
using their specific model of mobile phone, including software
and hardware configuration (this creates a customer service
• A destination to send or receive information through GPRS.
(Whereas with SMS this was often another mobile phone, in the
case of GPRS, it is likely to be an Internet address, since GPRS
is designed to make the Internet fully available to mobile users
for the first time.
Tremendously widening the limits and uses of mobile connections, GPRS
users can access any web page or other Internet applications.
Network Protocols Used
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 shown in Figure 4 on the next page.
• 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.
The efficiency and language of these briefs comes from the editing of architectural
H. Granbohm and J. Wiklund, GPRS: General Packet Radio Service, Ericsson Review,
vol. 76, no. 2, pp. 19-21, 2000.
-Figure 4 shows the GPRS protocol stack, Figures 5 and 6 show the GMS
system architecture and GPRS architecture respectively. I will discuss
Figures 5 next.
--In order to fully understand the building blocks of our topic,
GPRS, it suffices to first look at the make-up of the GMS system.
Figure 5 – GMS System Architecture (Source: Betterstetter et. al.)
Figure 5 shows the basic architecture of the public land mobile network
(PLMN) inherent to GSM technology. Other essential components are listed and
convenient legends exist at the bottom (thanks to Bettstetter et.al). The cell is
defined by the radio coverage of a base transceiver station (BTS). The BSC
(base station controller) controls several of these BTSs together, and these two
components together form the base station subsystem (BSS). The mobile
switching center routes the traffic of all of the mobile stations in the respective
cells. In the event of a connection originating from or terminating in the fixed
network, a specific gateway mobile switching center (GMSC) handles the
The hierarchy of the GSM network is as follows
• 1 MSC assigned to at least one administrative region
• Each administrative region is made up of at least one location area (LA)
• Several cell groups make up an LA
• Each cell group is designated to a BSC
Permanent data (e.g. user’s profile) and temporary data (e.g. current user
location) are stored in the HLR (home location register – a database). When a
call to a user is initiated the HLR is always the first to be contacted, to determine
the user’s location. A visited location register (VLR) stores the data of those
users who are currently in its area of responsibility (a group of location areas
[LAs]). The AUC serves security purposes and stores data such as keys for
encryption and authentication. Finally, the EIR – equipment identity register –
keeps track of equipment data rather than subscriber data.
Figure 6 – GPRS System Architecture (Source: Betterstetter et. al.)
GPRS Architecture (Figure 6, above)
If you’ll recall, in Chapter 1 (basics) we talked of two groundbreaking
nodes that make GPRS possible.
• Serving GPRS Support Node (SGSN)
• Gateway GPRS Support Node (GGSN)
These support nodes are necessary to integrate GPRS into the previously
established architecture of GSM. The support nodes (GSN) take on the task of
delivering and routing data packets between the mobile stations and the PDNs
(packet data network). Figure 6 shows the interfaces between these new nodes
and the GSM network. Notice how the signaling data is manipulated
The blue Gb interface connects the dinosaur component (BSC) with the
SGSN. Using two other, unique interfaces – Gn and Gp – user and signaling
data are both transmitted between the GSNs. The Gp interface is only used if
the two GSNs are in different PLMNs. Otherwise, the Gn interface is used
(GSNs are in the same PLMN). A backbone IP-based GPRS network is used to
connect all GSNs. Here the GSNs package the PDN packets and tunnel
(transmit) them using the GTP (GPRS tunneling protocol). The type of backbone
depends upon whether or not the GSNs exist within the same PLMN. Figure 6
shows two “intra-PLMN” backbones within an “inter-PLMN” network. Intra-PLMN
backbones have GSNs within the same PLMN, inter-PLMN networks have GSNs
in differing PLMN.
GPRS offers many new network features to mobile service operators. These
include packet switching, spectrum efficiency, Internet aware, and the support of
TDMA and GSM.
From a network operator perspective, GPRS involves overlaying packet
based air interference on the existing circuit switched GSM network. This gives
the user an option to use a packet-based data service. To supplement a circuit
switched network architecture with packet switching is quite a major upgrade.
The GPRS standard is delivered in a very elegant manner – with network
operators needing only to add a couple of new infrastructure nodes and making a
software upgrade to some existing network elements.
Packet switching means that GPRS radio resources are used only when
users are actually sending or receiving data. Rather than dedicating a radio
channel to a mobile data user for a fixed period of time, the available radio
resource can be concurrently shared between several users. This efficient use of
scarce radio resources means that large number of GPRS users can potentially
share the same bandwidth and be served from a single cell.
The actual number of users supported depends on the application being
used and how much data is being transferred. Because of the spectrum
efficiency of GPRS, there is less need to build in idle capacity that is only used in
peak hours. GPRS therefore lets network operators maximize the use of their
network resources in a dynamic and flexible way, along with user access to
resources and revenues. GPRS should improve the peak time capacity of a GSM
network since it simultaneously:
• ·Allocates scarce radio resources more efficiently by supporting virtual
• ·Migrates traffic that was previously sent using Circuit Switch Data to
• ·Reduces SMS Center and signaling channel loading by migrating
some traffic that previously was sent using SMS to GPRS instead
using the GPRS/SMS interconnect that is supported by the GPRS
For the first time, GPRS fully enables Mobile Internet functionality by
allowing interworking between the existing Internet and the new GPRS network.
Any service that is used over the fixed Internet today – File Transfer
Protocol (FTP), web browsing, chat, email, telnet – will be as available over the
mobile network because of GPRS. In fact, many network operators are
considering the opportunity to use GPRS to help become wireless Internet
Service Providers in their own right.
The World Wide Web is becoming the primary communications interface –
people access the Internet for entertainment and information collection, the
intranet for accessing company information and connecting with colleagues and
the extranet for accessing customers and suppliers. Web browsing is a very
important application for GPRS.
Because it uses the same protocols, the GPRS network can be viewed as
a sub-network of the Internet with GPRS capable mobile phones being viewed as
mobile hosts. This means that each GPRS terminal can potentially have its own
IP address and will be addressable as such.
SUPPORTS TDMA AND GSM
It should be noted that the General Packet Radio Service is not only a
service designed to be deployed on mobile networks that are based on the GSM
digital phone standard.
The IS-136 Time Division Multiple Access (TDMA) standard, popular in
North and South America, will also support GPRS. This follows an agreement to
follow the same evolution path towards third generation mobile phone networks
concluded in early 1999 by the industry associations that support these two
The first version of the GPRS standard is complete. The next version of
the standard, adds advanced features, such as point-to-multipoint
communications. Many GSM vendors, such as Alcatel, Ericsson, Lucent,
Motorola, Nokia, Nortel, and Siemens have played an active part in the standards
process. Recently, Lucent has announced a deal to bring Verizon to 3G. Cellular
service providers currently cover almost 90 percent of the population in the
United States. Figure 4 shows GPRS contracts, which currently have been
awarded to carriers in Europe, Asia and the United States.
Figure 7: GPRS Contracts Awarded
Country Carrier GPRS Core Infrastructure Vendor Contract Date
Austria Mobilkom Nortel Motorola/Nokia BSS an Nortel NA 7/99
Austria TELE.RING Alcatel Alcatel BSS + NSS + Microwave NA 5/20/99
Belgium Belgacom Motorola Siemens switches, Motorola, NA 3/15/99
Alcatel and Nokia base stations
Denmark Sonofon Nokia Nokia 6/2/99
Finland Radiolinja Nokia Nokia NA NA
Finland Sonera Nokia Nokia NA 2/23/99
Finland Sonera Ericsson Nokia NA 6/99
France France Telecom Alcatel Alcatel and Ericsson Mobile NA 4/2/99
(TRIAL) Switches, Alcatel, Nortel and
Motorola Base Stations
France France Telecom Motorola As above NA 3/99
France SFR/Cegetel Alcatel Alcatel and Ericsson mobile NA 10/21/98
switches, Alcatel, Motorola,
Nokia base stations
France Bouygues Nortel Nortel and Nokia BSS, Ericsson NA 7/99
Telecom (TRIAL) NSS
Germany T-Mobil Ericsson Alcatel and Siemens NA 1/26/99
switches.Alcatel, Motorola and
Lucent base stations
Germany T-Mobil Alcatel As above NA 2/23/99
Germany Mannesmann Siemens Siemens NA 6/99
Netherlands Telfort Ericsson Ericsson NA 2/23/99
Poland PTC/Era Siemens Siemens NA 6/99
Poland Polkomtel Nokia Nokia NA NA
Scandinavia Siemens 2/9/99
UK BT Cellnet Motorola Motorola $50 mil 3/18/99
UK One2One Ericsson Ericsson $45 mil 5/12/99
Australia C&W Optus Nortel Nokia BSS, Nortel NSS $33 mil 7/99
Hong Kong Sunday Nortel Nortel NSS, Nortel BSS NA 5/99
Hong Kong Hongkong Nokia HK$40-50 7/6/99
Hong Kong Smartone Ericsson Ericsson NA NA
Singapore Mobile One Nokia NA 2/8/99
Taiwan KGTelecom Nokia $100 mil
USA Omnipoint Ericsson Ericsson NA
Source: An Introduction to General Packet Radio Service, August 1, 2001 
GPRS gives subscribers access to data communication applications such
as e-mail, corporate networks, and the Internet using their mobile phones. The
GPRS service uses the existing GSM network and adds new packet-switching
network equipment. GPRS employs packet switching, which means that the
GPRS mobile phone has no dedicated circuit assigned to it. Only when data is
transferred is a physical channel created. After the data has been sent, it can be
assigned to other users. This allows for the most efficient use of the network.
When packet-switched data leaves the GPRS/GSM network, it is
transferred to TCP-IP networks such as the Internet or X.25.Thus, GPRS
includes new transmission and signaling procedures as well as new protocols for
interworking with the IP world and other standard packet networks. Mobile
phones currently available do not work with the new GPRS technology. The
industry’s mobile phone vendors are working on both existing and new phones
that will support both GSM and packet switching. It is also becoming more
common for laptops and PDA’s (Personal Digital Assistants) to have a GPRS
phone integrated in them.
Perfectly dubbed a 2.5G system the General Packet Radio Service has
bridged us to the 3G (UMTS) of today.
Technical Feature Listing
Data rate: Maximum of 171.2 kbps
Outer block coding
Inner Convolutional coding
Interleaving scheme for error bursts
Gaussian Minimum Shift Keying GMSK
Combination of TDMA & FDMA
Transmit Frequency bands
Mobile station Uplink Reverse ch. 890 – 915 MHz
Base station Downlink Forward ch. 935 – 960 MHz
Duplex seperation 45 MHz
RF carrier spacing 200 kHz
Total number of RF Duplex channels 124
Number of TDMA slots on each carrier 8
1 to 8 time slots per TDMA
One time slot (Physical channel) 0.577 ms
Frame Interval: 4.615 ms
Asymmetric data traffic
different time slots for Uplink and downlink
217 hops/s (slow)
16 µs time dispersion
Packet switched data networks such as IP and X.25
Gateway GPRS Support Node (GGSN) and
Serving GPRS Support Node (SGSN)
Packet data traffic channels
Packet common control channels
Packet dedicated control channels
Packet data broadcast control channel (only for forward link)
Precoding of Uplink Status Flag (USF)
Add Tail bits
Channel coding schemes
Scheme Peak Rate per slot (kbps) RLC Block size Code
CS-1 9.05 181 .5
CS-2 13.4 268 .66
CS-3 15.6 312 .75
CS-4 21.4 428 1.0
Standard Library Functions
The following is a list of the standard library functions to perform the
various aspects of GPRS. These functions can be implemented in a
DSP or the ARM RISC architecture. The channel models are used
for simulating the channel operating environment and are not a
function that would be implemented in a mobile handset or base
Precoding of uplink status flags
Convolutional coder (1/2, 2/3 and 3/4)
Interleaver / deinterleaver
Interleaver of depth 4 / deinterleaver
Propogation models for urban and rural areas
Modulator / demodulator
GMSK modulation / demodulation
2G Second generation; generic name for second generation of digital mobile networks (such
as GSM, and so on)
3G Third generation; generic name for next-generation mobile networks (Universal
Telecommunications System [UMTS], IMT-2000; sometimes GPRS is called 3G in North
3GPP 3G Partnership Project
BG Border gateway
BGP Border Gateway Protocol
bps Bits per second
BSC Base Station Controller
BTS Base transceiver station
CS Circuit switched
DHCP Dynamic Host Configuration Protocol
DNS Domain Name System
EDGE Enhanced data rates for GSM evolution; upgrade to GPRS systems that requires new
base stations and claims to increase bandwidth to 384 kbps
ETSI European Telecommunications Standards Institute
Gb Interface between a SGSN and a BSS
Gc Interface between a GGSN and a HLR
Gd Interface between a SMS-GMSC and a SGSN, and between a SMS-IWMSC and a
Gf Interface between a SGSN and an EIR
GGSN Gateway GPRS Support Node
Gi Reference point between GPRS and an external packet data network
GIWU GSM interworking unit
GMSC Gateway mobile services switching center
Gn Interface between two GSNs within the same PLMN
Gp Interface between two GSNs in different PLMNs
GPRS General Packet Radio Service; upgrade to existing 2G digital mobile networks to provide
higher-speed data services
Gr Interface between a SGSN and a HLR
Gs Interface between a SGSN and a MSC/VLR
GSM Global System for Mobile Communications; most widely deployed 2G digital cellular
mobile network standard
GSN GPRS Support Node (xGSN)
GTP GPRS Tunneling Protocol
HDLC High-Level Data Link Control
HLR Home location register
HSCSD High-speed circuit-switched data; software upgrade for cellular networks that gives each
subscriber 56K data
IP Internet Protocol
ISP Internet service provider
L2TP Layer two Tunneling Protocol
LLC Logical Link Control
MAC Medium Access Control
MM Mobility management
MS Mobile station
MSC Mobile services switching center
NAS Network access server
OA&M Operations, administration, and management
OSS Operations Support System
PCU Packet control unit
PDA Personal digital assistant
PDN Packet data network
PDP Packet Data Protocol
PLMN Public Land Mobile Network; generic name for all mobile wireless networks that use
earth base stations rather than satellites; the mobile equivalent of the PSTN
PSPDN Packet Switched Public Data Network
PSTN Public Switched Telephone Network
PVC Permanent virtual circuit
QoS Quality of service
RADIUS Remote Authentication Dial-In User Service
RLP Radio Link Protocol
SGSN Serving GPRS Support Node
SLA Service-level agreement
SMS Short message service
SMSC Short message service center
SS7 Signaling System Number 7
TCP Transmission Control Protocol
TE Terminal equipment
TDMA Narrowband digital TDMA standard; uses same frequencies as AMPS, thus is also
known as D-AMPS or digital AMPS
TS Time slot
Um Interface between the MS and the GPRS fixed network part
VAS Value-added services
VLR Visitor location register
VPN Virtual private network
WAP Wireless access Protocol; important protocol stack (Layers 4 through 7 of the OSI
model), used to send simplified Web pages to wireless devices; uses IP but replaces
TCP and Hypertext Transfer Protocol (HTTP) with UDP and WTP, and requires pages to
be written in WML rather than in HTML
Much of this table comes from the Cisco White Papers
Choi, Hahn, TechTV “The High-Speed Wireless World”,
March 21, 2001
Ericsson “Third Generation Mobile Systems”,
http://www.ericsson.com/3g/how/gprs.shtml, August 21, 2001,
“General Packet Radio Service”, http://www.utdallas.edu/~kim97/GPRS.htm,
“GPRS – General Packet Radio operator Service”,
“GSM Phase 2+ GPRS: Architecture, Protocols, and Air Interface”
GSM World “An Introduction to the General Packet Radio Service”,
http://www.gsmworld.com/technology/yes2gprs.html, August 1, 2001,
GSM World “An Overview of GPRS”, http://www.gsmworld.com/technology/gprs.html,
August 18, 2000,
Khoo, Ernest. “A CNET tutorial: What is GPRS?”
4,00.htm, July 19, 2001
Merritt, Tom, TechTV “GPRS Phones”,
November 13, 2000
Mobile and Wireless Overview “General Packet Radio Service (GPRS),
Mobile GPRS “About the General Packet Radio Service”, http://www.mobilegprs.com/
Motorola “BT Cellnet Showcases World’s First Commercial GPRS High Speed Mobile
Data Service At Networks 2000”, http://www.corporate-ir.net/ireye/ir_site.zhtml?
ticker=MOT&script=411&layout=-6&item_id…, June 27, 2000
Motorola “GPRS Solutions”, http://www.motorola.com/aspira/GPRS.htm
Nokia “GPRS Mobile On-line”, http://www.nokia.com/gprs/, 2001
Nokia 3G Solutions “Mobility Core”,
PsychoSpy and The Clone “A Guide to General Packet Radio Service”,
http://www.nettwerked.net/gprs.txt, September 2, 2000
Rysavy, Peter.Network Magazine “Emerging Technology: Clear Signals for General
Packet Radio Service”,
http://www.networkmagazine.com/article/NMG20001129S0002/3, December 5, 2000
Rysavy, Peter.Network Magazine “Emerging Technology: Clear Signals for General
Packet Radio Service”, http://www.rysavy.com/Articles/GPRS2/gprs2.html, December
Rysavy, Peter, “Paper: General Packet Radio Service (GPRS)”,
http://www.gsmdata.com/es53060/paprysavy.htm, September 30, 1998
“USA: Simplify GPRS – new GPRS high-speed wireless modem”,
Webopedia “GPRS”, http://www.webopedia.com/TERM/G/GPRS.html, August 6, 1999
“What is GPRS?”,http://www.mobiletelecoms.net/what_is_gprs.html
White Paper “Cisco - GPRS White Paper”,
http://www.cisco.com/warp/public/cc/so/neso/gprs/gprs_wp.htm, July 6, 2000
Wireless Communications Solutions “General Packet Radio Service (GPRS)”,