O2 Broadband noob query - What do HSPA and WCDMA stand for?

Mayo Exile

What do the above terms mean? Looking at the bottom of the statistics option, I get 3 bar strength when its HSPA. Then it will switch to WCDMA with strength going to 5 bars. Are they both different forms/types of 3G coverage?

Is one better than the other?

watty

HSDPA = High Speed Downlink Packet Access. A system running on W-CDMA and FOMA to increase speed from 340kbps to 3600kbps (but only for a single user using a sector, for multiple users the speed can drop to below 150kbps). The possible 7.2Mbps and 14.4Mbps speeds are only for one user at a time very close to a mast.

W-CDMA = Wideband Code Division Multiple Access. Needs at least 5MHz, usually FDD (Frequency Division Duplex = separate 5MHz TX and RX, but a shared TDD is possible. Time Division Duplex). ordinary CDMA is 1.25MHz carrier.

W-CDMA (also called UMTS and 3G, though FOMA and CDMA2000/EVDO rev A can be called 3G also), uses high speed frequency hopping. Each channel shares the same band, but has a different "hopping code". This means the more handsets or modems the poorer the Signal to Noise and thus sector shrinks dropping calls/connections and speed drops. Voice calls use the same space and usually have priority.

When the sector is busy or signal is poorer the connection will drop from HSDPA mode on W-CDMA to plain W-CDMA (plain 340kbps max approx 3G).

Mayo Exile

Ta Watty! A very comprehensive answer!

,8,1

W-CDMA (also called UMTS and 3G, though FOMA and CDMA2000/EVDO rev A can be called 3G also), uses high speed frequency hopping. Each channel shares the same band, but has a different "hopping code". This means the more handsets or modems the poorer the Signal to Noise and thus sector shrinks dropping calls/connections and speed drops. Voice calls use the same space and usually have priority.

Slightly OT question: could a TDMA-based system have been developed which would deliver "3G" type capacity (e.g. > 1Mbit downloads). Would it have any advantages over the CDMA-based UMTS system we currently use for 3G?

The GSM standard was TDMA and I think it was more reliable overall.

watty

It was developed.

It's called Flash-OFDM. Digiweb, Digita, T-Mobile and others in various countries use it. It uses OFDM for the carriers instead of the hopping CDMA carrier (A bit like Mobile WiMax). Mobile WiMax unfortunately has no spectrum lower than 2.6GHz and mostly 3.5GHz which makes it poor without fixed outdoor aerials.

It's about 4x better performance in 1/4 of the Radio Spectrum. There were two reasons for the 3G choice:
CDMA is simple to implement. F-OFDM and WiMax needs much more complex DSP (not an issue now).
Politics and Qualcomm.

The 2G competitor to GSM is CDMA on 1.25MHz channels (Mainly USA). 3G uses W-CDMA, 5MHz down + 5MHz up Channels.

Mobile WiMax is more recent and is still not in full service anywhere (Sprint/Clearwire on 2.6GHz in USA will be first, the failed Buzz network in Austrailia was Nomadic WiMax, like ripwave concept, though ripwave is CDMA based). Both it and Flash-OFDM are however data (IP) only networks that are good enough for VOIP calls. 3G is primarily a digital voice (not at all the same as VOIP) system with 340k Data sharing the same spectrum/capacity. HSDPA is a way of speeding up the data if there are not too many voice calls (still shares the capacity). Ironically EDGE on GSM can now deliver in theory 560kbps on existing masts with better capacity per MHz spectrum than 3G or HSDPA. In theory more than one user can get the top EDGE speed while there are calls too, while HSDPA can only deliver a sustained > 3Mbps speed for one user with no voice calls on the sector.
Neither is at all good at VOIP due to high Latency. If Irish Operators allocated more GSM capacity to EDGE, it could do VOIP better than 3G /HSDPA though.

measurement

I realise this is an old thread, but I've just got a smartphone....;)
I use the wifi option at home (I'm retired) and don't use the data option on the phone at all.
I'm not a heavy user, as far as I know (no online games etc.) but I noticed that my Eircom usage has doubled since I got the phone.
2 possible causes - someone has hijacked my WPA password, or the smartphone, set to "WCDMA(preferred)/GSM", is guzzling resources. I'm assuming its the phone, but should I set it to GSM only?
For now I'm going to just put the wifi on occasionally, e.g. when the laptop is off, but it means my email won't be checked. I used to only use about 30-40% of allowance, but I'm at 93% today.:(

Just in case its the WPA password, I changed it last night, and will do a test, with the phone switched on for a few days, at the start of next month, but any advice would be welcome.