Author: Martin

From a network perspective, LTE is of course the topic of the Mobile World Congress. This morning I met with Julius Robson of Nortel, who is chairman of the LTE/SAE Trial Initiative, or LSTI for short. I’ve been following the activities of the LSTI for some time now as their aim is not to repeat the mistakes made with UMTS in the past by not properly testing networks and mobile devices with each other before pushing them out into the market.

For the congress first results from the proof of concept phase are becoming available from a lot of vendors and I will report more on the details in the coming weeks. Here are some personal insights I gained during the meeting:

I’ve been a bit sceptical so far of the chances of TDD-LTE (Time Division Duplex) becoming a big technology outside China as most network operators in Europe, Asia and the Americas mostly have FDD (Frequency Divison Duplex) spectrum. To my surprise, it seems there are more than just a few network and mobile vendors who have reported results back to the LSTI on first TDD-LTE tests. They still seem to be a bit behind FDD-LTE but it’s not the tiny trickle I was expecting. Julius told me Nortel has worked on TDD-LTE as well and since everything above the physical layer is pretty much the same in FDD and TDD, only a few people were required to come up with the additional base station software for TDD in quite a short time. Quite a difference to TDD-UMTS which is a completely different game to FDD-UMTS used today.

Also, some mobile operators, for example in Europe, have TDD spectrum in the 2.1 GHz band that they bought together with the FDD spectrum during the UMTS auctions back in the year 2000. So far that invstment lies dormant. So if mobile devices do come out early that support both FDD and TDD than I think there might actually be a chance for TDD to be deployed alongside FDD in major markets outside China. Whether it’s as easy on the mobile side to have FDD and TDD combined in one chipset is another matter and I don’t have a lot of insight into this. Maybe I’ll find out more this afternoon as I’ll talk with some silicon manufacturers then.

In LTE, there are only two radio interface states, ACTIVE and IDLE. The LTE requirements say switching between the two states should take less than 100 ms. Looks like while this sounds ambitious from a HSPA perspective, were the switching time currently is in the range of one second, the goal seems to be reached by vendors even in the early stages. That’s good news as it makes the tradeoff very small between interactivity and power conservation from the mobile device point of view. So it will be interesting in the future to observe if Discontinuous Transmission (DTX) will be used a lot while in ACTIVE state to conserve energy or if the mobile is just set into IDLE state right away.

Time passes very quickly here at the Mobile World Congress and it’s already morning of day 2. Here are some thoughts I scribbled into my notebook yesterday which you might find interesting, too.

Apart from the N97, I’ve also taken a look at a couple of other things while at the Nokia booth. The beta version of Nokia Maps has been out for a while and after looking at it at the booth, I think it is time to upgrade on my N95 and wait for the half a gigabyte of map data to reload in the process. New features that have persuaded me are speed warnings, radar warnings, finally a navigation route overview option and, most importantly, integration of maps with Ovi on the PC, so I can plan routes and favorites on the PC and synch them with the mobile. A very nice feature.

Sportstracker has been upgraded as well and now supports Polar heartbeat monitors. Currently only available as a bundle with a new phone but with some luck at some point also available separately. I noticed that the heart rate of the presenter was higher than mine 🙂

Next on my list of things to do was to pick up the tickets for the Symbian Foundation evening event at their stand and to chat with some of the employees of where things are going. It seems things are still very much in flux and the next year will be an exciting one for those involved with the foundation.

I also went to see my book publisher Wiley in hall 2 (2A130) to prepare for my book presentation session on Wednesday afternoon from 2-4. The book is already selling well and I had the chance to talk with someone just picking up a copy while I was there. It’s always good to talk with people to see why they are picking up a copy. If you are around on Wednesday, please come around and say hello!

As I said, time flies and once that was done I was already on my way to the MobileMonday Global Peer Awards. As the event is quite big it was outside the Fira as every year, this time in the beautiful Palau de la Musica. The venue was not quite perfect for the event as the conference room was underground and there was absolutely no public network coverage. Some people, including me, were quite nervous not being reachable. It must be the times… Rudy de Waele was nice enough to give me instructions how to log on to the installed Wi-Fi network so I could at least send out e-mails that I am not reachable. Lots of people were at the event and I think the format to give each startup three minutes to present themselves was a good thing. Great event, Rudy, I guess you have done magic again for networking and getting the talk flowing. One thing I particularly noticed compared to previous years was that for startup companies the iPhone seems to have overtaken S60 as THE platform to develop for. Not sure an application store and an N97 will be enough for Nokia to reverse this trend. But they are certainly not sitting still so we’ll see what happens.

And finally in the evening we chilled out at the Symbian Foundation Party. As always lots of interesting people there to talk with, mobile and otherwise. A great first day and not much energy left afterwards.

Day 2 has just started now, let’s see what it brings.

During the day I ran a number of traffic tests on the public 3G network of Vodafone on the Mobile World Congress exhibition ground and I have to say I am very impressed by the results.

Even around high time with the main hall packed with people communicating, performance with my speed test application was around 700 kbit/s with peaks at 1.2 MBit/s. And this with all the people around me communicating and showing mobile Internet applications. One presenter at the Nokia booth even told me that she has switched to 3G for her demos as the Wi-Fi network they have installed couldn’t cope for one reason or the other. Now that’s something…

On the technical side my trace mobile shows that Vodafone is using three 5 MHz HSPA carriers. If the other three network operators do the same, there should be 12 carriers or 60 MHz of bandwidth used at the Fira for 3G. Even in the busy Barcelona city center currently only one carrier is used by Vodafone.

The tracer also detected only a single neighboring cell on one of the three carriers used, so neighbor cell interference must have been low, another must for getting high throughput. It’s probably a micro cell setup, although I have to walk around a bit more on the exhibition ground to confirm that.

GPRS performance in Vodafone’s 2G network was equally good with Opera Mini downloading web pages very quickly. A good indication that enough timeslots were free for data use.

On the voice side: All calls I made today mostly to other people at the exhibition connected very quickly and I never got a network busy response or people complaining I was not reachable.

I don’t think there are many other places in the world with wireless data and voice traffic as high as at the Congress except maybe Manhattan. So it’s good to see that despite the increasing use for Internet connectivity, well planned and deployed networks can do the job.

Here we go, day one at the Mobile World Congress and one of the first places for me to check out is of course the Nokia booth. While lots of people have reported about the new E75 and other devices having been launched this morning, I’ve been looking at some details of other already announced phones and applications which are of particular interest to me.

So everyone speaks about “Touch these days” and my next phone also needs to be one, too, no doubt about it. So I played around with a Nokia N97 for a bit to get a feel for the device and the touch screen. I really like the form factor of the device and also the sliding mechanism which tilts the screen while in the open position. Not only is it good for working with the phone while holding it but the screen can also very well be read when the phone sits on the desk. No complaints about the small keyboard either, I could type quite quickly with two fingers. With the new idle screen widgets it makes for an ideal central place to keep me updated on news, e-mails, social networking events and other bits and pieces that come in throughout the day.

I also very much like the finish of the device and the display resistance, it makes scrolling through web pages very easy and natural. The experience is much better than on the 5800 Express Music on which I find the screen surface a bit to resistive when quickly moving the finger over it to scroll down a page.

On the software side I think Nokia still has some work to do. Some things still feel a bit slow and other things such as the Gallery integration into other programs such as e-mail was still missing in the demo device they showed.

The other thing that I would like Nokia to improve a bit before launch is the built in browser. It doesn’t (yet?) reflow text and so on some pages the text is either tiny or one has to scroll left and right when zooming in. Also, scrolling does not work while the page is processed, something that I found quite irritating. Definitely not an easy thing to get working properly but I think it’s essential.

So all in all still a bit of mixed feelings on the N97 for the moment but with some luck the firmware that the first devices will be shipped with deal with these things. Can’t wait to get one then.

When I get on a new mobile network I usually give it a thorough check for my research and to discuss results with interested operators. Most already do application testing on their own such as how many videos are viewed without interruption or how fast web pages load, etc. However, some do overlook some other important parameters.

One of the first things I noticed in Vodafone’s 3G network here in Spain at the Mobile World Congress is that sometimes when I log into the network with my mobile phone and remain connected, the battery runs flat within only 2 hours. A bit of research revealed that the reason for this is that they are assigning public IP addresses for transparent Internet connections (via the APN airtelnet.es).

So you might wonder what the battery drain has to do with a public IP address assignment!? Well in theory, not much, but in practice, quite a lot. When getting assinged a public IP address, all IP packets to this address get routed to the mobile device no matter whether they are wanted or not. Since IP addresses are dynamically assigned the new holder of an IP address potentially gets the ‘leftover’ from a previous user and all the junk emitted from viruses and other malware on the Internet. While the mobile device doesn’t really care and discards those incoming packets, the radio link is constantly active instead of falling back to a power conserving state while no user data is exchanged.

In my case I noticed that in some cases when I attached to the network the air interface link was constantly kept up as every couple of seconds an unsolicited IP packet was received. Most operators use network address translation (NAT), which assings a private IP address to the mobile and thus fixes this issue.

A somewhat crude fix for this problem from the user side short of hooking up the mobile to a power source once an hour is to fall back on the 2G GPRS network. The unwanted IP packets still come in but the power consumption in 2G mode is significantly less as the air interface link is kept for a much shorter time than in 3G mode after the last IP packet has been received and also requires less power.

So Vodafone, while I appreciate a public IP address for my 3G notebook dongle I think it’s a particularly bad idea for battery driven devices and user statisfaction. Also from a network point of view this is far from ideal as it wastes significant ressources on the radio link that would better be used for real traffic.

PS: I’ve noticed that there is also an APN with private IP addresses but that seems to be only good for web surfing as all my other applications are blocked.

Like every year I will post live from the Mobile World Congress in Barcelona again and provide my own angle on the show off the beaten path. Last year, I had a Nokia N93 and a Nokia N800 Internet tablet with me for the job. This year I was thinking about replacing the N800 with my eeePC as the web browser of the N800 is just too slow, i.e. very painful to use. However, after some deliberation, I decided against it, it is just too heavy to carry around all day. The benefit from having a full web browser and spell checker is just not big enough. So I decided that less is more and I will exclusively use my Nokia N95 and my Bluetooth keyboard to keep me connected during the week. Let the show begin.