Date: Tue, 23 Jan 2001 14:38:09 +0000 (UTC) From: naddy@mips.inka.de (Christian Weisgerber) To: freebsd-chat@freebsd.org Subject: Re: VCD Message-ID: <94k50h$1hfe$1@kemoauc.mips.inka.de> References: <200101211447.f0LElEk04073@mobile.wemm.org> <20010121145018.A73989@citusc17.usc.edu> <20010121165422.A44505@peorth.iteration.net> <v04220821b691222656eb@[10.0.1.2]>
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Brad Knowles <brad.knowles@skynet.be> wrote: > Qualcomm invented Code Division Multiple Access (CDMA), the > superior digital cell phone technology that is the basis for all 3G > projects around the world. Basic code division multiplexing has been around for _decades_ in military equipment. Look up "spread spectrum". > CDMA is supplanting TDMA in the US, I wish people wouldn't throw around those terms in a fashion that makes them look like idiots. *DMA refers to "* Divison Multiple Access", which are very very basic terms that say nothing about implementation details. For the wildcard, plug in F(requency), T(ime), and C(ode) as applicable. GSM doesn't use TDMA. GSM uses F/TDMA. If forgot whether Qualcomm's system uses C/FDMA or C/F/TDMA. UMTS will use C/F/TDMA, of course. Instead of spouting *DMA buzzwords, refer to the actual system designation (e.g. "GSM"). > Anybody that has to replace TDMA technology with CDMA technology > winds up pretty much completely replacing the entire network they > built, which is why it's still taking time to make this conversion in > the US. However, Europe made the "leap" to TDMA technology in GSM, > before CDMA existed -- standard AMPS/NAMPS style analog cell phone > technology had been stretched beyond its limits, and they had no > choice but to go digital. This is the fairly common phenomenon of technology upgrades happening out of sync. The US turned their phone network digital long before Europe did, but when Europe moved to ISDN (a term that really refers to the network rather than subscriber lines), the American network was laughably obsolete, digital or not. As players leapfrog each other, the technological lead keeps changing. When Europe got serious about mobile networks, it was clear that analog schemes didn't have much future, so they came up with GSM. The US had a reasonably well-developed AMPS infrastructure, so (even ignoring politics) there was no reason to jump on the GSM bandwagon. Of course now that AMPS is unbearable any longer, technology has progressed beyond GSM. Well, considering how long the US carriers dragged their feet, maybe UMTS as GSM successor will manage to become a global standard. > Therefore, pretty much all European companies will end up ripping > out their entire set of existing TDMA-based GSM networks and > replacing them with brand-new CDMA-based 3G equipment. No, they will add UTMS equipment to their existing GSM stations. Both network types will coexist for some time, and part of the infrastructure (cell stations) can be re-used. > The same will happen in the US, as 3G takes over from existing > TDMA, CDMA, AMPS/NAMPS networks, but at least many of those companies > will have relatively less money thrown down the TDMA hole which they > then have to completely write off. My mobile comms lecturer termed what you call a TDMA hole "a license to print money", and I agree. What may come to haunt the carriers are the totally fucking insane amounts of money that were spent to acquire UMTS licenses. I don't know how this was handled in Belgium, but in some countries, e.g. Germany and the UK, the licenses to the UMTS spectrum were auctioned off by the regulatory bodies. The carriers payed a total of almost _50 billion_ euros for the German UMTS licenses alone. > Of course, US phones also have the concept of "multiple NAMs" > (Number Assignment Modules, i.e., account numbers), so that you can > actually have accounts on multiple different carriers, and switch > between them at your leisure. Many allow up to 99 NAMs on a single > phone. Just try that with a GSM. I don't have to try. I know people who use such SIMs daily. I've only seen this in company phones so far, so apparently it isn't pushed into the consumer market, but it does exist. -- Christian "naddy" Weisgerber naddy@mips.inka.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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