NODE 845a6c96GSM technology
azur@netcom.com (Steve Schear)Sat, 18 Jan 1997 14:44:50 -0800 (PST)
GSM DATA FEATURES
GSM is particularly suited for mobile data communications. All GSM base
systems support 9.6kbit/s circuit-switched data services, soon many will
increase transmission speed up to 28.8kbit/s. A new part of the GSM
standard, known as High Speed Circuit Switched Data (HSCSD), is being
developed which will boost user capacity up to 64 kbit/s, and higher.
Interconnecting this 64 kbit/s wireless capability with public ISDN
networks, for example, will give mobile users complete end-to-end digital
connectivity with the attendant benefits of very fast set-up times and high
link quality.
Technically, HSCSD requires a new radio link protocol; a
modification of the existing protocol used to provide the GSM voice
channel. GSM uses TDMA (Time Division Multiple Access) technology, which
divides each 200 kHz carrier into eight timeslots. To provide a single
voice channel, one timeslot is used; one timeslot is also used to provide a
single 9.6 kbit/s data circuit. However, all eight slots will be used to
provide one 64 kbit/s circuit.
The main benefit of this approach is that it is designed for the
existing GSM infra-structure. There is no need for operators to change
their entire network infrastructure in order to implement it. Operators
will therefore be able to implement HSCSD in a quick and efficient way,
once the specification has been ratified.
ENCRYPTED GSM LINKS
If the GSM phone includes a data port, as some already do, just connect
your laptop, dial your ISP and 'push' the encrypted traffic over that link
(e.g., using TCP/IP and PGPfone).
REFERENCES
If you really want to dive headfirst into GSM, the following is a resource
list generated in 1994:
@article(rahn,
author = {Rahnema, Moe},
title = "Overview of the {GSM} System and Protocol Architecture",
journal = {IEEE Communications Magazine},
month = {April},
year = 1993)
@incollection(chee,
author = {Cheeseman, David},
title = "The pan-{European} cellular mobile radio system",
booktitle = {Personal and Mobile Radio Systems},
editor = {R.C.V. Macario},
publisher = {Peter Peregrinus},
address = {London},
year = 1991)
@incollection(bals1,
author = {Balston, David M.},
title = "The pan-{European} cellular technology",
booktitle = {Personal and Mobile Radio Systems},
editor = {R.C.V. Macario},
publisher = {Peter Peregrinus},
address = {London},
year = 1991)
@article(moha,
author = {Mohan, Seshadri and Jain, Ravi},
title = "Two User Location Strategies for Personal Communication Services",
journal = {IEEE Personal Communications},
volume = 1,
number = 1,
year = 1994)
@inproceedings(haug,
author = {Haug, Thomas},
title = "Overview of the {GSM} Project",
booktitle = {EUROCON 88},
month = {June},
year = 1988)
@inproceedings(mall,
author = {Mallinder, Bernard J. T.},
title = "Specification Methodology Applied to the {GSM} System",
booktitle = {EUROCON 88},
month = {June},
year = 1988)
@inproceedings(aude,
author = {Audestad, Jan A.},
title = "Network Aspects of the {GSM} System",
booktitle = {EUROCON 88},
month = {June},
year = 1988)
@incollection(bals2,
author = {Balston, D. M.},
title = "The pan-{European} System: {GSM}",
booktitle = {Cellular Radio Systems},
editor = {Balston, D. M. and Macario, R.C.V.},
publisher = {Artech House},
address = {Boston},
year = 1993)
@incollection(wats,
author = {Watson, C.},
title = "Radio Equipment for {GSM}",
booktitle = {Cellular Radio Systems},
editor = {Balston, D. M. and Macario, R.C.V.},
publisher = {Artech House},
address = {Boston},
year = 1993)
@incollection(harr1,
author = {Harris, I.},
title = "Data in the {GSM} Cellular Network",
booktitle = {Cellular Radio Systems},
editor = {Balston, D. M. and Macario, R.C.V.},
publisher = {Artech House},
address = {Boston},
year = 1993)
@incollection(harr2,
author = {Harris, I.},
title = "Facsimile over Cellular Radio",
booktitle = {Cellular Radio Systems},
editor = {Balston, D. M. and Macario, R.C.V.},
publisher = {Artech House},
address = {Boston},
year = 1993)
@article(dech,
author = {D\'echaux, C. and Scheller, R.},
title = "What are {GSM} and {DCS}",
journal = {Electrical Communication},
month = {2nd Quarter},
year = 1993)
@article(feld,
author = {Feldmann, M. and Rissen, J. P.},
title = "{GSM} Network Systems and Overall System Integration",
journal = {Electrical Communication},
month = {2nd Quarter},
year = 1993)
@article(bezl,
author = {Bezler, M. and others},
title = "{GSM} Base Station System",
journal = {Electrical Communication},
month = {2nd Quarter},
year = 1993)
@article(schm,
author = {Schmid, E. H. and K\"ahler, M.},
title = "{GSM} Operation and Maintenance",
journal = {Electrical Communication},
month = {2nd Quarter},
year = 1993)
@article(lobe,
author = {Lobensommer, Hans and Mahner, Helmut},
title = "{GSM} -- a {European} Mobile Radio Standard for the
World Market",
journal = {Telcom Report International},
volume = 15,
number = {3-4},
year = 1992)
@article(hube,
author = {Huber, Josef--Franz},
title = "Advanced Equipment for an Advanced Network",
journal = {Telcom Report International},
volume = 15,
number = {3-4},
year = 1992)
@book(winc,
author = {Winch, Robert G.},
title = "Telecommunication Transmission Systems",
publisher = {McGraw-Hill},
address = {New York},
year = 1993)
@inproceedings(natv,
author = {Natvig, Jon E. and Hansen, Stein and de Brito, Jorge},
title = "Speech Processing in the pan-{European} Digital Mobile Radio
System ({GSM}) --- System Overview",
booktitle = {IEEE GLOBECOM 1989},
month = {November},
year = 1989)
@inproceedings(vary,
author = {Vary, P. and others},
title = "Speech Codec for the {European} Mobile Radio System",
booktitle = {IEEE GLOBECOM 1989},
month = {November},
year = 1989)
@inproceedings(sout,
author = {Southcott, C. B. and others},
title = "Voice Control of the pan-{European} Digital Mobile Radio System",
booktitle = {IEEE GLOBECOM 1989},
month = {November},
year = 1989)
@unpublished(nils,
author = {Nilsson, Torbjorn},
title = "Toward a New Era in Mobile Communications",
note = {http://193.78.100.33/ (Ericsson WWW server)})
PGP Fingerprint: FE 90 1A 95 9D EA 8D 61 81 2E CC A9 A4 4A FB A9
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Lamarr Labs | Voice: 1-702-658-2654
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NODE bb0a3750Re: GSM technology
Adam Back <aba@dcs.ex.ac.uk>Mon, 20 Jan 1997 02:46:37 -0800 (PST)
Steve Shear <azur@netcom.com> writes:
> [very useful explanation of GSM TDMA, and the new HSCSD]
64 kbit/s tied to ISDN is very nice technology.
> ENCRYPTED GSM LINKS
> If the GSM phone includes a data port, as some already do, just connect
> your laptop, dial your ISP and 'push' the encrypted traffic over that link
> (e.g., using TCP/IP and PGPfone).
This would obviously be possible, but to my mind reduces the appeal of
the system. Not every one has a laptop. Even if the potential user
does have a laptop, booting windows95, and starting up PGPfone is an
onerous task compared to just dialing a number on a mobile phone.
It's a user friendliness issue, and a question of ergonomics. A
mobile phone is more portable than a GSM phone with a laptop plugged
into the data port. You can't fit the laptop and GSM phone
combination into your shirt pocket. What are you going to use for a
handset? Radio operators headphone (with mike attached to the
headset) plugged into the laptop? That's more dangling wires, and
makes the system less portable, and even more onerous to setup (take
laptop from carry bag, plug in headphones, plug in phone data port,
wait for laptop to boot, etc).
Even for crypto enthousiasts, I would submit that many would neglect
to go through the hassle of going through PGPfone for most
conversations, and would instead just use the mobile phone in the
clear (or with A5 encryption). This for similar reasons to the
situation with PGP itself, many people rarely use PGP, even though
there is abundant software available to use it seamlessly with most
mail readers. (I can vouch for mailcrypt.el the emacs interface to
PGP, and use it for to anyone who has a PGP key, and does not express
displeasure at receiving encrypted email).
Also, the cell phone tarriffs may be higher if you need higher
bandwidth to get the software only voice codec implementations in
PGPfone to produce equivalent full-duplex voice quality to that
expected from a digital mobile phone.
Not knocking the mobile phone and laptop combination for the purpose
of having mobile TCP/IP access from a laptop, I know several people
who have this combination, though only at 9.6kbits, and even at that
speed it is very neat.
Adam
--
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