Author: Martin

I've been to a hotel recently that was just newly built and which had the latest window technology for heat insulation. That's all nice and well but for mobile networks on the outside, such windows are almost impenetrable.

The path loss through these windows were 30 db, so even a base station pointing directly at the hotel having a great 3G signal outside the hotel (-60 dbm) dropped to still acceptable (-90 dbm) just inside the hotel to a complete "nothing" just a few meters inside. Without dedicated in-house coverage via leaky cables, femtos, repeaters, etc., hotel guests are having a hard time if they want to use the networks outside.

Interestingly enough, standing close to a window helps but standing to a wall is actually much much better, the path loss in my case was only 10 db instead of 30. Quite a counter intuitive thing to do.

Having your Skype client open on your PC also means that your network can be used for relaying other Skype calls if the system detects incoming TCP/UDP connections can go through your NAT firewall (e.g. due to UPnP opening a few ports). It seems this doesn't happen very often as I haven't observed a relay session over my PC until recently, when I suddenly had a 200 kbit/s data stream in both direction running over my PC for several minutes.

Wireshark is always close at hand so I could quickly confirm that the data stream was indeed to and from the Skype client. A Reverse DNS lookup then revealed that the call was between two other PCs in Germany in networks of different providers. That probably means that the DSL routers in those networks do not have UPnP enabled, otherwise the IP packets could have been exchanged directly between the two parties. Also interesting to note was that the relaying went over my Wi-Fi. So unknowingly to those on the call their data packets went over a wireless link at least twice, probably even four times if you assume that both parties used Wi-Fi at their end as well.

ARCEP, the French regulator has reportedly given the go ahead to Iliad, also known as "Free" to officially launch their 3G network as they have fulfilled the initial minimum coverage condition as they now cover 27% of the French population with their own network. A national roaming agreement with France Telecom / Orange will do the rest for now. The Free network launch is the first in many years in Europe and it's actually the exception from the current norm of networks being combined in other countries to reduce competition. It's going to be interesting to see how well Free will be doing and what kind of effect it will have on competition and pricing in France. I wish them all the best, perhaps I can become a customer soon if they offer interesting prepaid packages!

The European Union is going through a difficult phase right now with lots of challenges but also lots of opportunities to further strengthen the integration of the European states. Obviously there are also the critics, mainly nationalists who are looking for salvation in isolation, doubting the benefits of a common market and a common future. But the madness of everyone going their own path can be shown in many areas and railways is a particular good example. What does this have to do with telecoms? Bear with me for a minute and find out.

Up until 10-15 years ago, every country in Europe used their own system for electric train power and signaling. The only thing that railways seemed to have in common was the same track width and even this changes when you go towards Eastern Europe. In other words, trains crossing country borders have to have several power adaptations, several different radios the driver has to know and understand several different signaling systems and the list goes on. An interesting example are the Thalys high speed trains that operate between France, Belgium, the Netherlands and Germany. Four countries and four different communication and signaling systems, and all within a journey time of 3 hours. Just crazy but a result of national planning and implementation without neighbors in mind.

To some this might seem but a small inconvenience but image the same would apply when you cross the border with your car. And it actually did until the early 1990’s. Before, each country had its own mobile communication system and mobile phones became pretty much useless when crossing the border. In some instances it was even forbidden to take the mobile device with you to prevent you from using it in the other country because radio waves could not be made to stop at the border. Crazy nowadays but perceived as normal only 20 years ago. And then GSM came along, one of the first children of European collaboration in the then young European Community. And evidently it has changed every country in Europe and pretty much the rest of the world afterwards. But when looking at how radio communication worked in Europe before the days of GSM, it has had the most profound influence here from a cooperation point of view. If nationalists had gotten their way back then I wonder how mobile communications would look today.

Now back to railway communication. Also here, GSM was accepted as the basis for voice and data communication and new pan-European railway tracks that are partly funded by the EU have to have a common signaling and communication system based on GSM, or it’s enhanced flavor GSM-R (GSM Railways). The data and signaling part of it is called ERTMS (European Rail Traffic Management System) and is used to replace national signaling systems. Thalys is one of the beneficiaries, using ERTMS as train control system on its journey through the different countries. The picture above recently taken in Cologne shows the ERTMS logo on a Thalys train.

Some where hesitant to join the club back then and some are hesitant to join it now. But if you are into telecoms history, here’s an account of someone late to the party, who has joined nevertheless and still made a profound positive impact despite of it. Enjoy and think about the story there and this blog entry here next time someone sees the end of the EU in sight.

The topic of providing Internet access at meetings keeps me interested and I have continued experimenting with different setups. One somewhat more sophisticated setup I've been working on lately is to physically separate the Wi-Fi and traffic shaping module for the meeting participants from the device that provides Internet connectivity (e.g. a 3G/LTE Router).

The best setup is of course to connect them via an Ethernet cable. In some situation this might not be possible, however, for example, when the 3G/LTE router has to sit outside the meeting room as there is no or insufficient coverage in the room. For such a scenario, a Wi-Fi link can provide the solution. But this is a bit more difficult than I thought at first. In my first setup I could only get a few megabits per second through the link.

Eventually, I figured out that the Wi-Fi access point that communicates with the participants and the Wi-Fi access point communicating with the 3G/LTE router interfere with each other, despite being on completely different Wi-Fi channels (one on channel 1, the other on channel 10). Separating the two devices by a meter and a half and the channel was suddenly much better and I could get around 15 MBit/s over the end to end channel (i.e. twice over Wi-Fi). After some more experimentation I figured out that I could even have the devices close together and get almost the full channel bandwidth (around 24 MBit/s), it's just a matter of how the antennas are placed.

Kind of reminds me of first HSDPA tests I did almost 5 years ago where slight changes in antenna orientation of the HSDPA card had stunning effects.

Here's two links today that give a very interesting overview of GSM, UMTS and LTE coverage in Germany today from two of the four network operators. I've chosen to link those two, because Vodafone and T-Mobile have built up significant LTE coverage over the past 18 months, especially in rural areas to bring high speed Internet coverage to small towns and villages. This was part of the license conditions for the 800 MHz digital dividend band and as can be seen on the maps it has born fruit.

On the T-Mobile map one can also see LTE coverage that will be switched on soon, most of it in big cities this time. The special thing about the Vodafone map is that UMTS and LTE coverage can be shown separately or together on the map and it's interesting to observe how LTE fills the gaps in UMTS coverage. 

I've been saving screenshots those coverage maps for years and it is quite interesting to see how 3G coverage expanded over the years. Initial 3G deployments looked quite different from the initial LTE deployments now as at that time, it was the big cities that were covered first rather than rural areas. This time around, license conditions have made the picture different and also, 3G in big cities with HSPA+, 64QAM and Dual Carrier extensions still has ample capacity to serve the needs there so there was no disadvantage to go for rural coverage first where often, only 2G was available.

About three to four years ago, 3G sticks for notebooks and netbooks started to take off and I assumed at the time that pretty quickly they would move inside the devices as mini-PCI adapters and use internal antennas wrapped around the display which would make reception even better. But to my surprise this hasn't really happened and few notebook are sold with a 3G card inside. Devices with antennas inside and SIM card slots waiting for a 3G card to be inserted are pretty rare as well. So what happened?

Perhaps there are several reasons for it: Notebooks for the masses go out for less than 600 euros for notebooks in many cases and less than 250 euros for netbooks. Adding a 3G card or even just antennas raise the price and make an offer less attractive compared to the competition. I wonder by how much the price would be raised!? Go to a supermarket in countries like Germany, Austria and some others and you can buy an entry level 3G USB stick for 20 to 30 euros, with a prepaid SIM card included and a couple of days or even a month of free surfing. Sure, the offer is subsidized by network operators but it's prepaid so it's unlikely a lot of money has gone into it. But USB sticks are simple, plug and play, no testing with a notebook whether it works or not like it is probably would have to be done for mini-PCI cards, etc. so I understand why it hasn't happened so far.

Another remedy might be tethering with mobile devices over WiFi which many smartphones offer today. Saves one the trouble of getting an extra SIM card and paying twice for data service, especially if only used occasionally or only lightly, e.g. during the daily commute where data intensive applications such as music and video streaming are not really an application anyway.

Yes, I know, as so often I am an exception but I would spend a few euros to get a mini-PCI 3G card for my netbook because that 3G USB dongle is just not really convenient…

 

A couple of weeks ago I blogged about how I managed to rescue data for a friend from Delicious which has changed owners and had a deadline for migrating the data that not everybody seems to have made. But it was only half a victory because I used to use Delicious myself and ever since it changed hands I was not happy with how the new owner developed the service. I frequently had to struggle with login problems which made adding new bookmarks a hassle and going back to the collection to search for a bookmark an equally uneasy process as well. Time to do something about it I finally thought over the weekend and look for a new place for my bookmarks.

The main reasons I had my bookmarks on Delicious was because I could access them from different devices, a typical cloud based service and obviously any other solution would have to do that as well. Recently, Firefox has also added this capability with its "sync" service. What's even better here is that the copy stored on the web is fully encrypted and the encryption key is with me. In other words, neither Mozilla nor anyone else can look into the encrypted container which is unlike many other services which promise you to encrypt the data for you but at the same time have the key to decrypt the data as well. Makes me wonder what the point of such encryption is in the first place.

So by migrating from Delicious to Firefox sync I would get two things at once, privacy of my data and a usable, cross device bookmarking service. But there is a little catch when migrating the bookmarks. Delicious does have the option to export bookmarks together with tags. Unfortunately, Firefox doesn't like the format and only imports the bookmarks but not the tags. Not a good thing because it's the tags that make the link collection useful. This is a tough one but I finally found this page which offers a script that converts the Delicious output to a format Firefox can understand.

The converted file can then be read into Firefox via the "restore" functionality. The catch with this one is that it overwrites the bookmarks that are stored locally. The solution is to export the local bookmarks into an HTML file and then import the ex-Delicious bookmarks via the "restore" function. Afterward, those bookmarks have to be moved to a separate folder and then the "import HTML" function restores the local bookmarks.

The whole process took me the better part of two hours to figure out but I'm glad I've done it. Not only is my data secure and private now with a copy in the cloud that only I have the ciphering keys for but syncing to a new device running Firefox (e.g. a pad) only takes a couple of seconds.

Excellent!

This week, the telecoms press spread a rumor that 3 Austria is in the final stages of negotiation with Orange Austria about a takeover. Interesting news but nobody really spends much thought if the Austrian regulator would actually allow such a move!?

In effect, such a takeover would reduce the number of independent networks from a healthy four to only three. Can the wireless market be healthy and competitive with only three network operators? If you don't hear anything about this deal anymore than I guess the regulator's answer was no.

Should they allow it, the consequences would be quite far reaching as once a network is gone it is quite unlikely a competitor would be interested in errecting a fourth one from scratch again, as the age for new wireless network operators is over.

It wouldn't be the first time a regulator said no to such a move, see Switzerland for example were a similar was just stopped recently at a much later stage by the regulator.

Any idea how much bandwidth a Youtube stream requires? Me neither so I recently took some time to have a closer look. Before reading on, take a guess.

Obviously, Youtube does not stream videos in the low compression format in which they are usually uploaded. In a test I did, the 1280x720p video I took with my smartphone had a data rate of about 11 MBit/s and a file size of around 45 megabytes for 32 seconds. Once uploaded and converted by Youtube the HD version of the video (720p) streams at around 2.7 MBit/s and has a total file size of around 11 megabytes. That's the format used by high resolution smartphones today. The default format (480p) version of my test video streams at around 1.2 MBit/s. I've also compared it to other professional content such as movie trailers and the data rates are about the same.

Interesting numbers and the next higher resolution is already in sight, 1280p. As for know, however, that is still rather the exception.