Disconnected UMTS

UMTS is probably the most common form of a so called 3G (third generation) mobile network. The 3G buzz has been aloud for almost six years now. The outrageous money spent by the operators on the spectrum licenses in early 2000's still weighs on the operator's balance sheets. The promise of lightning fast mobile networks is still around. But how is reality? I mean the average mobile phone user. Does she/he care?

There are three advantages promised to be delivered with the ascent of UMTS. First and the most spoken about has been the fast packet data transmission. Has it happened? It surely has. Last week I was stuck in a traffic jam in rainy Warsaw (btw Warsaw just stands still when it rains... I don't know why, but this is 100% reproducible). So sitting in a car I was checking mail on my Teleputer. One of my important customers asked me to forward him a product presentation. So I turned on my notebook, found the 4MB PowerPoint file, hooked the notebook to the UMTS Teleputer over Bluetooth and started sending the reply email with the 4MB presentation attached. It took just a few minutes and the file was at the customer's desk. Later I did a quick calculation and found out the actual uplink speed must have been in the region of 250-300kbps. At least ten times as fast as with GPRS or EDGE. I have been in similar situations a number of times and have to say UMTS delivers on its promise here (as long as you are within the coverage). But then I wonder how many people really want to upload a 4MB PowerPoint from a taxi cab...

Second advantage of 3G/UMTS has been for the operators themselves. The technology behind (W-CDMA or Wideband Code Division Multiple Access) simply allows for more people talking over the network. 2G/GSM networks in crowded cities are running at the edge of their capacity. They simply cannot accommodate more subscribers. With UMTS there is room. So operators do not have to stress us with high peak-time rates. They have enough capacity, so they let us talk. Even encourage us to talk more, by lowering the rates. Do we care? Yes, as long as the rates are lower indeed and as long as we do not get into network congestion that manifests itself by not being able to make a call.

Third advantage has been the ability to have video calls. Almost every UMTS handset has a forward facing video camera and we can actually see each other when talking. Personally I do not find this feature very exciting for person to person calls. This is a great technology for person to machine calls (imagine video calling your bank and just see the menus, account balances on the screen instead of having to listen to the long and boring voice prompts).

But what about voice? Has something changed here with the advent of all the latest technology and after mountains of money have been spent? I do not want to generalize here, but just from my experience - the voice part of all this glamour has been just terrible. Or even worse. I have been using several 3G/UMTS handsets (Nokia 6630, Nokia 6680, iMate Jasjar, HTC TyTN to name just a few). And they all share the same, terrible voice experience. All the handsets are multi-mode, they log on to the UMTS base stations when signal is available and they fall back to GSM otherwise. And whenever I am within the range of a 3G base station, there is at least 50% chance the callers will not reach me. Why? I have no idea. This must be some really big problem with the network itself. But this phenomenon is very predictable. Why do I know that? Because I keep on getting MCNs (Missed Call Notifications) - SMSes telling me somebody tried to reach me but failed. So I am on line (as I get those MCNs) but when you call me, there is at least 50% chance you will hear an announcement telling you I am out of the network service area or my phone is off. I get those MCNs, call back and the call is completed. Well fine, thanks God we (or the operators) have the MCN systems in place (those who do not -my company has a very good MCN solution, so come and ask), as in the end we can talk and operators recover the lost revenue (a lot!).

Why is that? Well, to be honest I don't know, I can just speculate. What I have noticed, is the missed calls happen most of the time when I am at the edge of 3G/UMTS coverage. If you think this is not common, you are wrong. UMTS (unfortunately) works at 2100MHz, and this frequency has very poor ability to penetrate buildings. So whenever you are indoors, you are probably at the edge. And when you are at the edge, your phone tries to switch back to GSM. Then you walk close to the window and the 3G/UMTS reception is better and the handset switches back to UMTS. And it is somewhere within that back and forth switching process that the incoming calls are lost. Not nice. Not nice at all. I suppose the transition to UMTS would generate a huge drop in call completion ratio, and probably missed call notification systems rescue the operator's voice revenue. I have noticed another UMTS phenomenon that proves the 3G to 2G (UMTS to GSM) handoff does not work as expected. I live outside the city and on my way home there is no 3G coverage yet. Very often I drive home having a phone conversation. The conversation starts on a 3G (UMTS) network and as I leave the city it is handed off to the 2G (GSM) network. I even know the point where it happens. Why? Because most of the time the conversation breaks down at that point. And if it does not, all I can hear is a modem-like sound instead of my conversation party. The modem-like sounds is a 3G-encoded voice (AMR codec) being directly transmitted to the 2G network and down to my phone working in 2G (GSM mode). GSM requires voice to be encoded with GSM-compatible codec, and AMR is not one of them. The network obviously knows I am on the 2G part, yet it still feeds me with 3G-encoded voice.

All this proves 3G/UMTS is still in its infancy. Errors like 3G to 2G handoffs should not simply happen. Everybody seems to be so fascinated with data transmission capabilities, they simply forget what people use their phones for and what service (hint: voice!) still pays the bill. In the end this all will be sorted out, I believe, but in the meantime, it is good we have MCN systems to save us.