Kevin Brennan wrote:
>>>>> Since I'm not a specialist on the air interface for 3G I will refer to
> the Harri Holma and Antti Toskala book
Ah. but I'm a real communications engineer. Weaned on Shannon &
Nyquist. Studied , tested and analysed GSM/ GPRS/EDGE/EDGE2, W-CDMA
based FOMA and 3G/HSDPA/HSUPA/HSPA+, Mobile WiMax, Flash-OFDM,
IPWireless, DVB-h+ DVB-RCT, and LTE for mobile data and VOIP. Also
WiDox, Full DOCSIS over Wireless, VSAT, Fixed WiMax, Proprietary Fixed
Wireless, Nomadic S-CDMA (Ripwave) and WiFi Municipal Mesh for Data
I've even looked at the issues of IPTV and VOD on these and on DSL and
>> "the maximum number of simultaneous users per sector per 5Mhz
> carrier"...."with HSPA release 7" ...is estimated to be "120 users"
> .. then more on reasons why a flat architecture is of benefit...
>At which point you'd be lucky to get dialup speed. The **total** cell
throughput then with 14.4 or 21 or 42MBps peak speed mast will then be
1Mbps to 2Mbps shared among the 120 users.
You can't beat mathematics and physics. Mobile systems operate near the
shannon limit. Thus you have 1/4 speed (shared) everytime you double the
Mobile Phone companies make all their money from SMS and voice.
Data makes them no money. LTE will cost to them at least 100 Euro a
Gigabyte, inc getting ROI in a sensible time frame.
Mobile Data is for occasional use On The Go / Mobile phones / Gadgets.
It's not viable for VOIP nor as a replacement for Fixed Wireless, DSL,
fibre or Cable.
You do realise that DSL is only limited by backhaul, and eircoms
existing 3Mbps DSL has x10 to x20 average performance of 14.4Mbps I-HSPA
I get 5Mbps+ at peak time and 28ms ping to Heanet on Fixed
Wireless and rarely ever better than 700kbps @ 150ms latency on
O2 at home, and frequently lower speed and 500ms in some places in
Dublin on HSDPA.
Nokia's own research concludes that VOIP is on average a poor experience
on HSDPA. SIP (and Skype clients in a new model) in Nokia phones are
really for WiFi in Home /Office. 3's Skype phone uses iSkoot a
Java client that uses GPRS, EDGE or 3G to set up a call and
then ordinary 3G voice (not VOIP) to 3's basement Skype Client to
convert to VOIP. That's actually the best model for Mobile Skype, but
of course not at all actually VOIP on 3's Network.
3G modems are not Broadband replacements, or even Fixed Wireless
Replacement. MOBILE Data will never be reliable as VOIP / Broadband
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