John Higdon <john@zygot.ati.com> (06/08/90)
While shopping today in a local electronics emporium, the new Motorola
handhelds caught my eye. My venerable GE Mini is pushing three years
old now and is definitely dated. These Motorolas looked pretty neat
and could be carried much more easily than the old GE.
As I started to attract the attention of a salestype, the sinking
feeling hit. With the rush to develop digital cellular, buying any
currently available cellular radio would be a major mistake. The
question concerning its obsolescence is not "if" but "how soon?"
The cellular industry may be shooting itself in the foot. Just when
roaming agreements and other standardizations are beginning to make
mobile telephone service worthwhile, digital promises to undo all of
that. In an area such as LA, where digital will undoubtedly appear
early on, a customer could buy a radio that would be virtually useless
elsewhere (such as the Bay Area, where digital will be much slower in
coming.)
Or else we will have the standard electronics industry fix: make the
customer carry around a bulky "multi-lingual" radio until the
manufacturers and service providers decide just what they are going to
do and when they are going to do it.
Frankly, I am so put off by this sudden about face ("suddenly we can't
do without digital") that I may just keep my GE Mini until there is no
more analog service, and then just do without. I hope other cellular
users vote with their pocketbooks as well.
John Higdon | P. O. Box 7648 | +1 408 723 1395
john@zygot.ati.com | San Jose, CA 95150 | M o o !king@uunet.uu.net (Steven King) (06/09/90)
In article <8797@accuvax.nwu.edu> John Higdon <john@zygot.ati.com> writes: >As I started to attract the attention of a salestype, the sinking >feeling hit. With the rush to develop digital cellular, buying any >currently available cellular radio would be a major mistake. The >question concerning its obsolescence is not "if" but "how soon?" Fear not, good gentle. There is is HUGE base of people out there who have analog phones. Cellular operators can't expect them all to buy new phones overnight. They'll start by installing a few digital channels and gradually phasing out the analog. I suspect that you'll still be able to get an analog channel anywhere you go for many, many years. >Or else we will have the standard electronics industry fix: make the >customer carry around a bulky "multi-lingual" radio until the >manufacturers and service providers decide just what they are going to >do and when they are going to do it. Give that man a cee-gar! I suspect that in the near future you'll have your choice of buying a pure-analog, a pure-digital, or a hybrid mobile. With the mixture of analog and digital channels available the hybrid shouldn't be strictly necessary, but it has the advantage of pure-digital in that you can enjoy the benefits of digital where that's available and still be able to use it in service areas that haven't upgraded yet. (Yes, I know that the "benefits" of digital from the user perspective are debatable. Let's not open that up again, eh?) You sound like you don't like this idea. Can you suggest an alternative? As I see it, a gradual phase-in is very much preferable to an overnight switch to the new technology. >Frankly, I am so put off by this sudden about face ("suddenly we can't >do without digital") that I may just keep my GE Mini until there is no >more analog service, and then just do without. I hope other cellular >users vote with their pocketbooks as well. Why the hostility here? No one will be forcing you to go to digital, at least not for a very long time. As I said, I don't think the operating companies can afford to blow off the huge installed base of analog customers. The main purpose of digital (as I see it, anyway; yes, I am involved with cellular, but only tangentially with digital) is to squeeze some extra channels out of a limited amount of bandwidth. A purely digital system has three times the number of channels that an analog system does. THAT'S why we "suddenly can't do without digital". The airwaves are getting full! Steve King, Motorola Cellular (...uunet!motcid!king)
peter@ficc.ferranti.com (Peter da Silva) (06/10/90)
In article <8826@accuvax.nwu.edu> motcid!king@uunet.uu.net (Steven King) writes: > A purely digital system has three times the number of > channels that an analog system does. THAT'S why we "suddenly can't do > without digital". The airwaves are getting full! I thought one idea behind cellular was to push the cells closer together when that happened. Put in more, smaller cells. And do the digital phones have the same bandwidth as the analog ones? Do they still give you a full-time 3 KHz channel, suitable for modeming? `-_-' Peter da Silva. +1 713 274 5180. <peter@ficc.ferranti.com> 'U` Have you hugged your wolf today? <peter@sugar.hackercorp.com> @FIN Dirty words: Zhghnyyl erphefvir vayvar shapgvbaf.
segal@uunet.uu.net> (06/11/90)
peter@ficc.ferranti.com (Peter da Silva) writes: >I thought one idea behind cellular was to push the cells closer together >when that happened. Put in more, smaller cells. There is a limit to how small a cell can be. Once that limit is reached, the only way to increase capacity is to add more channels. When you run out of channels, you have maxed out the system. Digital cellular will allow many more channels in a given cell. >And do the digital phones have the same bandwidth as the analog ones? >Do they still give you a full-time 3 KHz channel, suitable for >modeming? If you mean "can I put a modem on the phone?", the answer is "no". If you mean "can I still access analog data services?", the answer is "yes", if the digital cellular system is properly designed. A properly designed digital cellular system is best described as a radio ISDN (Integrated Services Digital Netork), that has one B (bearer) channel that is capable of transmitting data or compressed voice. Typical data rates on the B channel are anywhere from 6kbps to 24kbps, depending on the system. To send voice down this pipe, it must be compressed. Because of the compression, it is impossible to send most modem modulations down the B channel (300 buad Frequancy Shift Keying [FSK] might work, but not 2400bps V.22bis or 9600bps V.32). In order to allow subsribers to access modem based data services, these systems make provisions for a modem pool (again, much like an ISDN) at the connection point to the PSTN (Public Switched Telephone Network). With a modem pool, the connection from the modem to the mobile terminal is digital. Data rates can be up to the maximum B channel rate of the system. In addition, the system can supply an error correcting or error controlling protocol to run between the modem pool and the mobile terminals, giving the subscribe a much cleaner link then could ever be established in an analog cellular enviroment. In addition, connection to an ISDN is straight forward. Digital Cellular will be a great improvent over analog cellular for both the subscribers and the providers. For providers, more subsribers can be supported. For subscribers, ISDN like data services will be available from a mobile phone. As an example of digital cellular done well, I suggest you watch what is happening in Europe, with the Pan-Euorpean Digital Cellular standard (also called GSM). Gary Segal ...!uunet!motcid!segal +1-708-632-2354 Motorola INC., 1501 W. Shure Drive, Arlington Heights IL, 60004 The opinions expressed above are those of the author, and do not consititue the opinions of Motorola INC.
bp@ucbvax.berkeley.edu> (06/12/90)
From what I've seen of the digital cellular format, it seems to be a
way of ripping off the customer to reduce the carrier's overhead. The
real fix for high-traffic zones is to add more cells, not increase the
capacity of the existing ones at the expense of fidelity and
reliability.
If there is to be a digital format, it should be able to handle DATA.
Using TDM between three moving transmitters on the same channel will
probably work poorly even for voice.
Would anyone like to help me petition the FCC on this one?
Bruce Perens
{ucbvax,sun}!pixar!bppeter@ficc.ferranti.com (Peter da Silva) (06/13/90)
In article <8863@accuvax.nwu.edu> motcid!segal@uunet.uu.net (Gary Segal) writes: > If you mean "can I put a modem on the phone?", the answer is "no". [ and goes on to suggest a solution ] > In order to allow subsribers to access modem based data services, > these systems make provisions for a modem pool (again, much like an > ISDN) at the connection point to the PSTN (Public Switched Telephone > Network). And what do they have at that point? 2400 baud only? V.32 as well? How about PEP? Ever hear of the Telebit Cellblazer? What about TDD services? There are too many different sorts of modems out there for this to be a credible alternative. `-_-' Peter da Silva. +1 713 274 5180. <peter@ficc.ferranti.com> 'U` Have you hugged your wolf today? <peter@sugar.hackercorp.com> @FIN Dirty words: Zhghnyyl erphefvir vayvar shapgvbaf.
ahlenius@uunet.uu.net (Mark Ahlenius) (06/13/90)
pixar!bp@ucbvax.berkeley.edu (Bruce Perens) writes: > From what I've seen of the digital cellular format, it seems to be a >way of ripping off the customer to reduce the carrier's overhead. The >real fix for high-traffic zones is to add more cells, not increase the >capacity of the existing ones at the expense of fidelity and >reliability. The problem is that there is a limit on how small you can make cells and still retain "in-building" coverage. Cell splitting (i.e. making smaller cells out of larger ones to increase traffic capacity) can only be done up to a limit. Cell costs are high and so is the real estate needed for the base station. You just don't plop down cells anywhere you have traffic problems and hope that solves your problems. Added new cells or splitting existing ones has affects on the rest of your systems frequency plan. Thus you may have to retune existing cells and/or shuffle channels around to permit the new cell to work properly. It is a complex problem. There is also a limitation on the number of radio channels that can be installed in a cell site - due to the frequency reuse pattern (i.e. N=4, 7, 12, etc.). Also the FCC has placed a limit on the present bandwidth allotted for analog cellular. Do you consider the (more expensive) pcm type trunks that MA bell has installed across the country a rip off - because they can have 24, 48, ... conversations going across the same pair of wires? I hope not - they developed this technology for efficient use of a resource and that is what digital cellular is also working towards. Mark Ahlenius voice:(708)-632-5346 email: uunet!motcid!ahleniusm Motorola Inc. fax: (708)-632-2413 Arlington, Hts. IL, USA 60004
mk59200@metso.tut.fi (Kolkka Markku Olavi) (06/15/90)
In article <8863@accuvax.nwu.edu> motcid!segal@uunet.uu.net (Gary Segal) writes: >As an example of digital cellular done well, I suggest you watch what >is happening in Europe, with the Pan-Euorpean Digital Cellular >standard (also called GSM). ^^^^^^^^^^^^ Actually it's Global System Mobile, but it seems that the US is again going to isolate themselves from the rest of the world by using a incompatible nonstandard system. With GSM, you could have a single system working anywhere, just like the NMT system works currently in the Nordic countries. Markku Kolkka mk59200@tut.fi