General
Packet Radio Service (GPRS)
by Rachel Keller
TABLE OF CONTENTS
CONCLUSION
APPENDIX
Figure 7: GPRS as an extension of other packet networks. [20]
Figure 8: Tunneling with VPN technology. [20]
Figure 9: GPRS system. [20]
by Rachel Keller
TABLE OF CONTENTS
Introduction…………………………………………………………………3
Present State of Nature……………………………………………………...3
History………………………………………………………………………7
Shortcomings………………………………………………………………..8
Proposed Solution…………………….……………………………………10
User Features……………………………………………………………….10
Network Features…………………………………………………………...12
Industry Participation……………………………………………………….14
GPRS Phones……………………………………………………………….16
Method of Operation………………………………………………………..17
Applications…………………………………………………………………18
Methodology………………………………………………………………..19
Conclusion…………………………………………………………………..19
References…………………………………………………………………..20
INTRODUCTION
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.
PRESENT STATE OF NATURE
General Packet Radio Service, more commonly known as GPRS, is a new non-voice, value added, high-speed, packet-switching technology, for GSM (Global System for Mobile Communications) networks. It 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.
GPRS
offers a continuous connection to the Internet for mobile phone and computer
users.Experience has shown that
most data communication applications do not require continuous data transfer.Users
may need to be connected to a data communication network (such as a LAN,
WAN, the Internet, or a corporate Intranet), but that does not mean they
are sending and receiving data at all times. [2] Data transfer needs are
not generally balanced.In the majority
of cases, users will tend to send out small messages but receive large
downloads.Therefore, most of the
data transfer is in one direction.
GPRS
is expected to provide a significant boost to mobile data usage and usefulness.
It is expected to greatly alter and improve the end-user experience of
mobile data computing, by making it possible and cost-effective to remain
constantly connected, as well as to send and receive data at much higher
speeds than today.Its main innovations
are that it is packet based, that it will increase data transmission speeds,
and that it will extend the Internet connection all the way to the mobile
PC – the user will no longer need to dial up to a separate ISP. [11]
It
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
will also provide the type of data capabilities planned for “third generation”
cellular networks, but years ahead of them. [11] Figure 1 below is a timeframe
of GSM data services and their availability.
Figure 1: Road Map of Data Services for GSM
Timeframe
|
Capabilities
|
Notes
|
|
9.6 kbps service
|
Available today
|
Circuit-switched data and fax
|
|
14.4 kbps service
|
Available today
|
Higher speed circuit-switched data and fax
|
Works identically to 9.6 kbps service only at higher
speed
|
Direct IP Access
|
Available through some carriers today
|
Circuit-switched connection directly to Internet
|
Reduces call set-up time and provides a stepping-stone
to packet data.
|
High-speed circuit-switched data service (HSCSD)
|
Available today
|
High speed rates to 56 kbps
|
A software-only upgrade for carriers not requiring
expensive infrastructure.
|
GPRS
|
Available today
|
High speed packet data with transmission speeds
over 100 kbps, with most user devices offering about 56 kbps
|
Extremely capable and flexible mobile communications.
|
EDGE
|
Available within three years
|
High speed packet data which will triple the rates
available with GPRS
|
Final high-speed data technology for existing networks.
|
Third generation cellular
|
Available within three to five years
|
High speed packet data to 2 Mbps
|
Completely new airlink.
|
Source: Paper: General Packet Radio Service (GPRS),
September 30, 1998 [4]
|
|||
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. [9] 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)
Source: A CNET tutorial, July 2001. [9]
|
||||
GPRS could
possibly be the technology that will allow consumers to really begin to
sue the mobile Internet.GPRS is
considered one step ahead of HSCSD (High Speed Circuit Switched Data) and
a step towards 3G (Third-generation) networks. [9] It is the step to 2.5G
for GSM and TDMA (Time Division Multiple Access) service providers.Cingular
and AT&T are both currently the standard.
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. [15]
HISTORY
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 is not yet fully defined, but is expected to support 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.
[7] See Figure 3 below for a timeline history of GPRS.
Throughout
1999-2000
|
Network operators place trial and commercial contracts
for GPRS infrastructure.
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 quantities.
|
Throughout 2001
|
Network operators launch GPRS services commercially
an roll out GPRS.
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
GPRS usage.
|
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 [7]
|
|
SHORTCOMINGS
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. [7]
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. [7] 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.
SUBOPTIMAL MODULATION
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. [7]
TRANSIT DELAYS
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 standard.
PROPOSED
SOLUTION
General
Packet Radio Service will be coming 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.
USER
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
will allow 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. [23]
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.
SERVICE ACCESS
To
use GPRS, the user will need:
·A
mobile phone or terminal that supports GPRS (existing GSM phones do not
support GPRS)
·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 requirement)
·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. [23]
NETWORK
FEATURES
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.
PACKET SWITCHING
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. [23]
SPECTRUM EFFICIENCY
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. [23]
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. [23]
GPRS
should improve the peak time capacity of a GSM network since it simultaneously:
·Allocates
scarce radio resources more efficiently by supporting virtual connectivity
·Migrates
traffic that was previously sent using Circuit Switch Data to GPRS instead
·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 standards. [23]
INTERNET AWARE
For
the first time, GPRS fully enables Mobile Internet functionality by allowing
interworking between the existing Internet and the new GPRS network. [23]
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.
[23]
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. [23]
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. [23]
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. [23]
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 network types. [23]
INDUSTRY
PARTICIPATION
The
first version of the GPRS standard is complete.The
next version of the standard, which is expected to add advanced features,
such as point-to-multipoint communications is in development. 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. [4] Figure 4 shows GPRS contracts, which currently have
been awarded to carriers in Europe, Asia and the United States.
Figure 4: GPRS Contracts Awarded
The
GPRS standard supports both X.25 and IP, the two top Internet protocols,
but it is more likely that GPRS vendors and operators will put emphasis
on the IP service.It is also likely
that GPRS will first roll out in European countries.All
new GSM phones will support GPRS.
GPRS
PHONES
Phone
manufacturers, not to be outdone, have launched a number of GPRS-enabled
models for early adopters.The catch
is that the GPRS network is currently still not commercially available.Even
when all of this is available, the actual data transfer rate will depend
on the phone as well as the network operators.And
when it comes to pricing, the charging model could be by time, by packets
transferred, or a combination of both. [9] Figure 5 below shows current
mobile phone vendors GPRS models and the launch dates for these products
to reach the market.
Figure 5: GPRS Phone Models and Availability to Consumers
MODEL |
AVAILABILITY |
Alcatel One Touch 701
|
No launch details
|
Ericsson T39
|
Due by September
|
Ericsson T68
|
End of 2001
|
Ericsson R520m
|
Q2 of 2001
|
Motorola Accompli
|
End of 2001
|
Nokia 6310
|
Q4 of 2001
|
Nokia 8310
|
Q3 of 2001
|
Panasonic GD95
|
Q3 of 2001
|
Siemens S45
|
Due in August 2001
|
Siemens ME45
|
Due by September 2001
|
Trium Sirius
|
Due in August
|
Trium Mondo
|
Due in August
|
Sources: A CNET Tutorial,
July 2001 [9] and GPRS Phones, November 2000 [10]
|
|
METHOD
OF OPERATION
GPRS gives GSM 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. [2] 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. [2] Mobile phones
currently available do not work with the new GPRS technology.The
industry’s mobile phone vendors are working on new phones that will support
both GSM and packet switching.There
is also a possibility in the future, that laptops and PDA’s (Personal Digital
Assistants) will have GPRS phone integrated in them.Figure
6 is a diagram of the GPRS Network Architecture.
Figure 6: GPRS Network Architecture
METHODOLOGY
For
this research project, I chose to use the Internet as a means of finding
a topic for to use as an emerging technology.After
several keywords searches in various search engines and after checking
out technology sites such as http://www.cnet.com
and http://www.zdnet.com,
I chose my current topic, General Packet Radio Service.My
next step after picking a topic to research was to actually search the
Internet and find out if there would be enough information out there for
me to conduct a research project.The
initial search I did on Google™ using the keywords “General Packet Radio
Service” brought back 184,000 results.I
began searching these and came up with about twenty-four Internet articles
that were pertinent to what I was needing for my research project.I
figured the easiest way of going through all of this information was to
just print everything out and then read through it.
In
my opinion, I feel that Nokia has the safest approach to GPRS.Instead
of trying to perform so much at once, they offer consumers such things
as web access.Once GPRS is made
available, I think that it will really add to the reliability and mobility
of cellular phones.Until then, consumers
will have to wait until Verizon or Pacific Bell announce a deal on GPRS.The
GPRS-enabled phones are not going to be great on their own; it is going
to take service providers and operators to make them great.So,
until then, even the most hopeful company won’t put a GPRS phone out on
the market.
REFERENCES
[1] Agilent Technologies “Agilent Understanding General
Packet Radio Service (GPRS)”, downloaded 9/28/01.
[2] Choi, Hahn, TechTV “The High-Speed Wireless World”,
http://www.techtv.com/products/consumerelectronics/story/0,23008,3317919,00.html,
March 21, 2001, downloaded 11/1/01.
[3] Ericsson “Third Generation Mobile Systems”, http://www.ericsson.com/3g/how/gprs.shtml,
August 21, 2001, downloaded 9/28/01.
[4] “General Packet Radio Service”, http://www.utdallas.edu/~kim97/GPRS.htm,
downloaded 11/1/01.
[5] “GPRS – General Packet Radio operator Service”,
http://translate.google.com/translate_c?hl=en&sl+fr&u=http://mircolease.com/fr/helpd,
downloaded 11/1/01.
[6] GPRS, http://whatis.techtarget.com/definition/0,289893,sid9_gci213689,00.html,
downloaded 9/19/01.
[7] GSM World “An Introduction to the General Packet
Radio Service”, http://www.gsmworld.com/technology/yes2gprs.html,
August 1, 2001, downloaded 9/19/01.
[8] GSM World “An Overview of GPRS”, http://www.gsmworld.com/technology/gprs.html,
August 18, 2000, downloaded 9/19/01.
[9] Khoo, Ernest. “A CNET tutorial: What is GPRS?”
http://www.singapore.cnet.com/handphones/wirelesscenter/story/0,2000027283,20097934,00.htm,
July 19, 2001, downloaded 11/1/01.
[10] Merritt, Tom, TechTV “GPRS Phones”, http://www.techtv.com/freshgear/comdexfall2000/story/0,23008,3011391,00.html,
November 13, 2000, downloaded 11/1/01.
[11] Mobile and Wireless Overview “General Packet
Radio Service (GPRS), http://www.wheatstone.net/whatwedo/Portal/Standards/gprs.htm,
downloaded 11/1/01.
[12] Mobile GPRS “About the General Packet Radio Service”,
http://www.mobilegprs.com/, downloaded
9/29/01.
[13] 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, downloaded 9/28/01.
[14] Motorola “GPRS Solutions”, http://www.motorola.com/aspira/GPRS.htm,
downloaded 9/28/01.
[15] Nokia “GPRS Mobile On-line”, http://www.nokia.com/gprs/,
2001, downloaded 9/28/01.
[16] Nokia 3G Solutions “Mobility Core”, http://www.nokia.com/3g/solutions_mobility_gprs.html,
2001, downloaded 9/19/01.
[17] PsychoSpy and The Clone “A Guide to General Packet
Radio Service”, http://www.nettwerked.net/gprs.txt,
September 2, 2000, downloaded 11/1/01.
[18] Rysavy, Peter.Network
Magazine “Emerging Technology: Clear Signals for General Packet Radio Service”,
http://www.networkmagazine.com/article/NMG20001129S0002/3,
December 5, 2000, downloaded 9/19/01.
[19] Rysavy, Peter.Network
Magazine “Emerging Technology: Clear Signals for General Packet Radio Service”,
http://www.rysavy.com/Articles/GPRS2/gprs2.html,
December 2000, downloaded 9/13/01.
[20] Rysavy, Peter, “Paper: General Packet Radio Service
(GPRS)”, http://www.gsmdata.com/es53060/paprysavy.htm,
September 30, 1998, downloaded 9/29/01.
[21] “USA: Simplify GPRS – new GPRS high-speed wireless
modem”, http://www.mobileapplicationsinitiative.com/lopsedel/dokument.asp?ID=News7064&Fran=Si,
downloaded 9/28/01.
[22] Webopedia “GPRS”, http://www.webopedia.com/TERM/G/GPRS.html,
August 6, 1999, downloaded 9/19/01.
[23] “What is GPRS?”,http://www.mobiletelecoms.net/what_is_gprs.html,
downloaded 11/1/01.
[24] White Paper “Cisco - GPRS White Paper”, http://www.cisco.com/warp/public/cc/so/neso/gprs/gprs_wp.htm,
July 6, 2000, downloaded 9/19/01.
[25] Wireless Communications Solutions “General Packet
Radio Service (GPRS)”, http://www.nuntius.com/solutions22.html,
downloaded 9/28/01.
Figure 7: GPRS as an extension of other packet networks. [20]
Figure 8: Tunneling with VPN technology. [20]
Figure 9: GPRS system. [20]
No comments:
Post a Comment
its cool