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In case you have a good memory, the title of this post may sound familiar. Back in October last year, I wrote a post on a paper published by Ericsson in which they came to the conclusion that as networks evolve and demand for mobile Internet access rises, the cost of transporting one gigabyte of data over a wireless network can be in the range of 1 Euro. Now NSN has published a similar paper and come to the same conclusion. A very interesting read as they explain very well how they come to their conclusion. It's also in line with the calculations I made in my recent book and it's good to see that the assumptions I made at the time were also made by others to estimate capacity.

An interesting twist of the paper is that it breaks with this nice little graph you might be familiar with showing that as Internet use rises in wireless networks, there's a rift opening up between revenue and amount of CAPEX and OPEX if things left as they are today. The paper actually says that the reverse can  happen if network operators evolve their networks: The more the network is used, i.e. the more people pay a monthly usage fee for wireless Internet access, the cheaper it gets per subscriber to transport a certain amount of data for the network operator.

Finally, the German spectrum auction for everything between 800 MHz and 2.6 GHz assigned for cellular services has ended. While the media mostly reports the €4.4 billion as a disappointment for the German government, I personally think it's more than enough for a few pieces of thin air. And, as a side note, compared to the sums paid in the Netherlands and in the Nordic countries, it's a respectable sum. Now it's in the hands of the four incumbent mobile network operators to make the best use of their new spectrum in the coming years. For the details on who has acquired what have a look here.

Dean Bubley over at Disruptive Wireless has recently published an interesting post in which he wonders whether he has or will have a problem with Wi-Fi and femto offload in the future.

He describes how he is walking from his home to the tube station and his mobile device in the pocket picking up several known Wi-Fi hotspots from BT and connecting to them for a couple of seconds just to loose them again. This wreaks havoc on applications that are actively exchanging information over the network even when the phone is not actively used as the connection is dropped every time. An interesting point he makes there and I don't have a single and simple solution for it but some things come to my mind on how to deal with this:

On the Wi-Fi side:

• The connection manager could wait for a couple of seconds checking the signal strength and only connecting when it stays relatively constant, i.e. the user is not moving and hence, the Wi-Fi hotspot is worth using.

• Distinguish between public Wi-Fi hotspots where such rules should be applied and encrypted home / office hotspots for which it could apply different rules.

• A good Wi-Fi offload solution would be not to get a new IP address in every new hotspot and to break the 3G connectivity. Ideally, an IP tunnel is used so no matter whether connected over 3G or Wi-Fi the device would always use the same IP address. That would also deal with the security issues of unencrypted public Wi-Fi hotspots.

On the Femto side:

• I think there would be less of a problem here because GSM, UMTS and LTE offer myriads of possibilities to ensure a mobile only uses a femto if it is not moving.
• There is no need to assign a new IP address when hopping between femtos so connectivity would not be broken when jumping into or out of a femto.
• The connection can be handed over from and to a femto so continued connectivity with little or no outage can be ensured.
• Access to a femto can be restricted. This book goes into the details of this.

So, yes, small cells are a challenge for mobility but there are options to deal with this.

In the days where notebooks were too big to carry around with, too expensive to buy a smaller one just for the purpose and too heavy for the bag I tried to get as much done as  possible with the mobile phone. Writing a blog entry on the phone, a section for the next book or a lengthy e-mail with a foldable keyboard  was practical but never quite enjoyable.

It's not that the user experience could not have been better but the software never developed much beyond it's original incarnation. Over the years I never got a spell checker, no 'app' today to make blogging a bit easier from Typepad and viewing PDF documents on my mobile remains a pain to this day. While it remained the only choice it was better than just keeping my thoughts for later.

The netbook I bought last year, however, pretty much changed the game for me. With a small battery and weighing less than a kilogram, my netbook comfortably fits in my bag, resumes from suspend in just a few seconds and the screen size and processing power is sufficient to comfortably do all the described tasks above plus more. Even opening it up for just 5 minutes to do a quick task is viable and 3G plus Wi-Fi connect me instantly.

That doesn't mean of course that I no longer carry a mobile phone, I just use it less for content creation but more for consumption oriented tasks these days such as web browsing, feed reading and for getting instant e-mail notification. Ah yes, and for phone calls of course. That makes me think that now that the keyboard has become less important I might try a touch based phone again.

A quick post today to make those of you who are interested in the finer details of LTE aware of an interesting post by Zahid Ghadialy over at the 3G and 4G Wireless blog on LTE conformance testing. Towards the end of the post, Zahid links to a couple of simulator test cases developed by 3GPP RAN5 and the GCF for which actual logs are attached. In other words, the theory you can learn from books is taken into practice there and you can see how the signaling messages look like between the mobile and the network and what their contents are. Great stuff, thanks Zahid!

23 auction days, 186 rounds and there is still no end in sight in the German Spectrum auction for 800, 1800, 2100 and 2600 GHz frequencies.

While for some time, there was hectic bidding for spectrum in the 800 MHz digital dividend band, things seem to be settled there for the moment as there hasn't been any movement there since day 16. If things remain there as they are right now, all four network operators will own spectrum for around €420 million per 2×5 MHz slot. Vodafone and T-Mobile each hold slots each while Telefonica/O2 and E-Plus
(KPN) each hold one slot. Out of the €3.2 billion currently in the pot, €2.5 billion are for the 800 MHz band. In other words, all the rest can be had for cheap.

Since bidding in the 800 MHz band has halted, things have been trickling along. Since day 16, the total sum has 'only' increased by €0.4 billion. The auction will only resume next Monday due to a public holiday in Germany on Thursday. So how much longer will it still drag out? I hope not too long anymore…

Ever since I read this book on how mobile networks have spread in Africa and discovered Eric Hersman's blog on technology and life in Africa in the process, I've been following his stories of what's going on there. In case you are planning a trip to Kenya and wonder how to best stay connected to the Internet, here's a recent post of Eric in which he describes how he keeps connected. Should be applicable to other countries in Africa as well. Makes for an interesting read and reminds me of the early days of GSM and GPRS in other parts of the world!

Most public Wi-Fi hotspots use no encryption and hence, communication is not very secure. Using a VPN as discussed here and here solves the issue but very few people are actually aware of the problem and willing to take such measures. So far I thought there is little that can be done from the network side as the WPA Pre-Shared Key (PSK) method is ineffective if everybody uses the same key (password) as network monitoring tools can decode the encrypted traffic if the key is known and the authentication and ciphering dialogue is captured. But then I remembered that the University of Vienna offers secure Wi-Fi Internet access so I checked out how they are doing it.

It turns out that they are using individual EAP password authentication from which a Wi-Fi ciphering key (WPA2, AES)  is then calculated. The username and password used in the Wi-Fi authentication process is the student's username and password for the campus network, stored at a central place for all sorts of purposes, including Wi-Fi authentication and encryption. As each student uses individual authentication credentials, monitoring the authentication dialogue will not yield the keys to decode the ciphered traffic later-on. A very elegant solution that just requires support in the Wi-Fi access point for WPA2 enterprise authentication. On the client side, support is already built into the operating system. It's quite clumsy to set-up with Windows XP but with Windows Vista, Windows 7, Linux and Mac OS the configuration is straight forward. It even works with Symbian and Android devices and the iPhone.

The only catch of this solution: The server certificate is not provided, that would have to be done offline, i.e. it's too complicated. That means that the device can't authenticate the network and hence a rouge access point could be used for a man in the middle attack.

Yes, bandwidth requirements are rising, especially when you have a big screen and lots of GHz available for things like high resolution video telephony. I use Skype video telephony quite often these days and when the other end also has a multi-megabit per second uplink available and a good camera, the video quality is just awesome and the stream easily exceeds one megabit per second in each direction. In other words, during a 60 minute video call, over 1 GB of data is exchanged.

Let's compare that to a mobile voice (only) call that uses a 12.2 kbit/s bearer for its codec over the air interface. 2 * 12.2 kbit/s * 60 seconds * 60 minutes / 8 bit = 11 MByte per hour. There's two orders of magnitude of difference here, i.e. a single high quality Skype video call uses the same bandwidth as 100 mobile voice calls! In fixed line networks, voice calls are usually transported in 64 kbit/s channels but the difference is still 1:20. And I imagine video telephony in full-HD resolution is not too far away anymore pushing the numbers even further.

Interesting result from the Dutch 2.6 GHz spectrum auction and one I have difficulties to interpret. Three incumbents and two newcomers have bid for the 2x 70 MHz of spectrum resulting in:

• one newcomer getting 2x 25 MHz
• the second newcomer getting 2x 20 MHz
• two incumbents each getting 2x 10 MHz
• one incumbent getting 2x 5 MHz

Lightreading's Michelle Donegan is the only one on the net I've seen so far writing a meaningful report about it and calling the stunningly low result of €2.6 million paid by the five “some loose change they [the network operators] found down the back of their car seats”.

According to Lightreading, a bandwidth cap was in place to prevent incumbents from bidding for all of the spectrum but I don't quite understand how much that was in practice. In any case the resulting spectrum the incumbents now have in 2.6 GHz seems very strange to me. Having 20 MHz is something you can build a fat carrier with and get speeds far beyond what is possible with HSPA today. But 10 MHz is an awfully small carrier for LTE in this band and I completely fail to see what you do with just 5 MHz!?

Also I haven't seen a country yet where 5 network operators have really made it over time. So instead of fighting it out over an auction, are some companies speculating with a merger down the road to get some fixed line or wireless assets and further spectrum in the 2.6 GHz band? Not sure if the auction rules allow for mergers later on but at least the money lost would be negligible in case the spectrum would have to be returned.