Talk:CdmaOne/Archive 1

Archive 1

Article not good

So compared to the GSM discussion, this page is pretty pathetic. I'm surprised. — Preceding unsigned comment added by 158.147.59.99 (talk • contribs) 08:49, 7 August 2004‎

Yes, this is not very good at all. I think that the CDMAOne technical stuff should be either moved to another article or put in a seperate section, and get some of the readable stuff in the article..unfortunetely I know nothing about the system, and if someone could write a proper article I might ;) — Preceding unsigned comment added by 72.141.64.79 (talk • contribs) 16:22, 17 February 2006‎

Cost

"Since larger numbers of phones can be served by smaller numbers of cell-sites, CDMA-based standards have a significant economic advantage over TDMA-based standards, or the oldest cellular standards that used frequency-division multiplexing."

Is this true? In europe the discussion has been that the switch to CDMA-based UMTS is very expensive since they need a much higher concentration of base stations. Or is this a UMTS-specific thing? --83.233.145.199 10:01, 15 July 2006 (UTC)

Per my understanding, the need for many UTMS sites is mostly related to uses that require massive bandwidth. If you want more BW to your mobile devices without reducing the number of users, you either need more spectrum to operate in, or you put up more cell sites (making your cells smaller and reusing the frequency more). If you can live without watching TV or downloading mp3s on your cell phone while driving, then you won't need so many extra sites. (humor intended) Marvin Glenn 07:55, 24 September 2006 (UTC)

Also need to add the fact that most european UMTS radio access is operating in 2100MHz band and compared to 850MHz band this has higher RF losses and its coverage and inbuilding pentration becomes a problem for the RF link budget for the capacity if offers. Roughly one needs 1/2 as many base stations in 850MHz or 900MHz band comapred to 2100MHz band to achive the same coverage for the same capacity per base station. However as the earlier argument suggest if one also needs the flexiable and higher capacity that is offered by UMTS then one needs more base stations. Also there is more bandwidth avalable at 2100MHz compared with 850MHz or 900 MHz allocation by ITU, hence one base station can manage more carriers in this band. In my understading 2100MHz or higher bands are useful to provide capacity in small cell sizes while 850MHz or 900Mhz bands provide better coverage however the number of carriers availbe in this band is limited. Hfalaki 10:31, 11 April 2007 (UTC)HFalaki

It is true, for the same operating frequency CDMA is more efficient than TDMA. The difference between IS-95 and UMTS lies in their default operating frequency 850 MHz and 2100 Mhz, thus UMTS requires more sites for the same area (however it also provides much more capacity, since there are more sites, CDMA is more efficient and UMTS has more bandwidth available) -- Figarema 22:51, 29 August 2007 (UTC)

2100 Mhz is only the default operating frequency for UMTS in Europe; although I believe they have relaxed this so it can now be deployed on 900 and 1800 Mhz. networks as well. The larger issue is that UMTS requires one 10 mhz. contiguous chunk of spectrum for one channel, whereas Qualcomm CDMA requires 2.5 for a single channel; although this is not as wide as a UMTS channel, it allows operators more flexibility with limited spectrum... that said, everyone is moving towards LTE now, both on CDMA and UMTS sides, and that can be deployed with as small as 3 Mhz, although in practice 10 Mhz or larger channels are primarily used. Also IS-95 CDMA and GSM-based standards have completely wiped out TDMA (D AMPS) in the Americas -- most (if not all) networks that were previously TDMA have now moved to CDMA or GSM-based systems since 2009. I am no longer aware of any TDMA-based (D AMPS) systems in existence -- one of the last ones being on the north slope of Alaska (ASTAC) which converted to GSM/UMTS a few years back. — Preceding unsigned comment added by 71.231.45.69 (talk) 19:52, 21 December 2013 (UTC)

"Also IS-95 CDMA and GSM-based standards have completely wiped out TDMA (D AMPS) in the Americas -- most (if not all) networks that were previously TDMA have now moved to CDMA or GSM-based systems since 2009" is irrelevant to this discussion, as we're discussing the code division multiple access and time division multiple access channel access methods, not the D-AMPS networks that are called "TDMA" networks or the Qualcomm IS-95 and CDMA2000 networks that are called "CDMA" networks. 2G GSM is TDMA-based, as it uses time division multiple access; UMTS is CDMA-based, as it uses code division multiple access - and 2G GSM service is still being offered; my first-generation iPhone still works as a phone, and it only supports 2G GSM, no UMTS. However, it'll cease to be a useful phone in 2017, as AT&T are shutting down their 2G service in 2017. Guy Harris (talk) 22:39, 29 June 2015 (UTC)

"Unlike TDMA, a competing system used in 2G GSM, all radios can be active all the time, because network capacity does not directly limit the number of active radios. Since larger numbers of phones can be served by smaller numbers of cell-sites, CDMA-based standards have a significant economic advantage over TDMA-based standards, or the oldest cellular standards that used frequency-division multiplexing."
This of cause is so shortened that it does not help. It is true, that under certain circumstances CDMA allows more connections. That is, if many users are close to the base station. CDMA is more flexible than TDMA, therefore it might allow more users a certain level of service. With TDMA any extra capacity that is available is used to save energy, with CDMA it may be used to add another call. --Moritzgedig (talk) 18:36, 29 June 2015 (UTC)

Archive 1