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 --------------------------------------------------------------------- Steve Schear (N7ZEZ) | Internet: azur@netcom.com Lamarr Labs | Voice: 1-702-658-2654 7075 West Gowan Road | Fax: 1-702-658-2673 Suite 2148 | Las Vegas, NV 89129 | --------------------------------------------------------------------- Internet, electronic currency and wireless development 1935 will go down in history! For the first time a civilized nation has full gun registration! Our streets will be safer, our police more efficient, and the world will follow our lead in the future! --Adolf Hitler
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 -- print pack"C*",split/\D+/,`echo "16iII*o\U@{$/=$z;[(pop,pop,unpack"H*",<> )]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`
On Fri, 17 Jan 1997, Adam Back wrote:
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.
Does anyone use ADSL lines? or are they still very expensive?
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). [...]
participants (3)
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Adam Back -
azur＠netcom.com -
Nurdane Oksas