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I've grown quite fond of my Android based pad lately and use it for quite a number of things from web browsing to book reading. However, there are some limitations that will hopefully be removed in upcoming software versions.

Researching something usually involves opening a number of web pages, documents and PDF files, to switch between them quickly and to search in them. All of these things are not ideally implemented yet as the user interface is designed to only show one application at a time. Sure, Android is multitasking and holding down the home button for a second shows the list of applications one can switch to but it is too slow. When the mind is racing and making cross connections, you don't want to wait for a second.

Also, my web browser and pdf document reader only show one page at a time. In case of the web browser it is possible to open several pages at once. However, switching between requires swiping in a menu and then selecting the other page. A tab like on the PC is much more convenient for this. And the PDF reader, well, it can only open one file at a time. Not ideal at all for switching.

Obviously, most people will use a pad to perform one task linearly, but it has potential for much more. For the moment, however, I think this is the big limitation for me. Even if you add a keyboard and thus make a pad "almost" into a netbook, the ease of switching between applications and doing things simultaneously are nowhere near what you can do with a full operating system. Quite on purpose but it doesn't help me.

When spinning this thought further I think this is also the rift between pads and small mobile devices. On mobile phone type of devices, I definitely don't want tabs in apps or an always visible menu to switch applications quickly. Here, the screen is just too small. But on a tab, the screen is by far big enough to allow for all that. Having one operating system for both is challenging and requires at least a customized UI for the different device types.

One of the things that need to change before mobile VoIP without an option to fall back to a circuit switched channel can become as ubiquitous and reliable as today's circuit switched voice calls is the network infrastructure. While in some countries 3G is very well established by now, even there it is by no means as widely deployed as GSM. There are two dimensions to this. The first is that 3G is not as yet as widely deployed in rural areas as GSM. And the second dimension is the spectrum. In Europe, for example, 3G is deployed in 2100 MHz which doesn't reach as far indoors as GSM, which is mostly deployed in 900 MHz.

In some countries, such as Japan, massive in-house coverage enhancements is the solution. And Japan needs it for sure as it fully relies on 3G for voice telephony, although, for the moment, still with their traditional circuit switched technology, which, however, is probably largely virtual by now as all links are now likely based on IP technology.

Another approach is to drive wireless broadband connectivity to a lower spectrum range. UMTS can be run in the 900 MHz band these days, with many phones already supporting it. And with LTE on 800 MHz in Europe, even more spectrum can be lit up for broadband indoor penetration. I am very much looking forward to the first LTE 800 MHz networks coming on air in cities to see by how much this will enhance mobile broadband indoor coverage.

Another issue with a few question marks attached to it is capacity and quality of service. The first application that will break once a cell becomes congested is the voice service. So either the network has enough capacity and is built out sufficiently or QoS mechanisms have to keep a voice call going. Pretty difficult to predict.

Speaking of capacity. Once a cellular network is deployed on different frequencies, intelligent networks need to ensure a device is always on the right frequency layer. No need for a device to be stuck on 800 MHz while it is outdoor and has good reception of another frequency layer and vice versa. It's going to be interesting to watch how this area develops and what kind of solutions infrastructure vendors will come up with.

Returning to the “no circuit switched fallback option” mentioned below for a second: I wonder a bit if upgrading the RAN is not simpler in the end than to achieve CS/PS interworking and connecting the VoIP services to today's mobile voice infrastructure!?

Here's an interesting development that's going to bug hotel guests and owners equally soon: Many hotels these days offer Wi-Fi, some as part of the room price, some for an extra fee. Many of them give out individual codes so the Wi-Fi can be used with a single device. However, with Wi-Fi capable devices such as smartphones and especially pads, more and more hotel guests will show up with several devices requiring network access. And let's say you come with your family so the count certainly doesn't end with two devices. It's going to be interesting how hotels will adapt to the change in user behavior.

Here's an interesting article from Teltarif, a German telecoms website about the extension of mobile network coverage in the Munich tube. According to the article, the cost of 20 base stations and 125 antennas to cover additional 80km of tunnels and 20 underground stations was shared between the four network operators of the country. One of them, Vodafone, was the technical lead to get the extension up and running. It's not mentioned whether it's 2G only coverage or whether 3G coverage has been added as well. Can anyone from Munich comment?

The article ends with the note that previously, polls have always indicated that a majority of passengers was against mobile network coverage in the tube. Lately, however, that has changed significantly, perhaps, as the article speculates, due to the rise of Internet use on mobile devices.

One of the things that is just as important as capacity on the UMTS or LTE air interface is the ability to shuffle the data back and forth between a base station and the rest of the network. This link is called the "backhaul" and for data rates beyond just a couple of megabits, fiber connections or microwave Ethernet links are required. Recently, Ericsson has released an interesting paper that describes the state of the art and the future of microwave backhaul.

So here are some technical details I found quite interesting: Like everywhere in telecoms, it seems there is an ETSI version (European Technical Standards Institute) of the equipment used globally and an ANSI version (American National Standards Institute) for the Americas. The current state of backhauling uses up to 56 MHz wide channels, and 256 QAM modulation and the maximum transmission power is given as around 2 watts. Traditional (virtual) E1 connections can be mixed with Ethernet connectivity and the Ethernet line rate on such a link is 345 MBit/s, equaling 80 traditional E1 lines. That is good enough for a combined GSM, UMTS and LTE base station today with three sectors, as 100 MBit/s per sector is unlikely to be achieved simultaneously in all three sectors. For more technical details see their data sheet.

The smallest channel offered by Ericsson's current product is a 3.5 MHz Channel and QPK modulation, resulting in a line rate of 2 E1s, equaling 4.1 MBit/s. The spec sheet that can be found here also reveals that dish antennas can be used with a diameter from 0.2m and single polarization up to dishes with 3.7m diameter and dual polarized antennas inside.

Used frequencies in ETSI land are anywhere between 6 and 38 GHz today, so far above the current frequency bands used between the base station and actual user devices, which transmit and receive anywhere between 700 MHz and 2600 MHz today. As high frequencies and high modulation are sensitive to rain a bandwidth adaptation feature ensures that during bad weather the line rate is reduced to ensure the link stays up.

I also had a quick look a competing microwave solution from Dragonwave to see where they are at the moment. They claim that their current microwave compact product is capable of speeds in the order of 800 MBit/s. That's about twice that of the Ericsson product and is likely because they use XPIC (cross polarization interference cancelation), which allows two data streams to be sent over the same channel simultaneously. Some but unfortunately not very detailed information can be found here.

So what does the future hold? Ericsson says that the 80 GHz band looks promising for microwave in the future, 112 MHz channels should be introduced shortly and 4×4 MIMO via two separate antennas and XPIC in each antenna will push microwave backhaul datarates beyond 1 Gbit/s.

 

I just don't get it!? I just had a look at a number of books on Amazon when I realized that each and every one of them was significantly more expensive in the Kindle version than in print!? Too successful already? I guess I will stick to printed books then, like them much more anyway. It leaves me clueless…

And another follow up on the history trail of the first GSM call in a commercial network 20 years ago to the post about the state of GSM back in 1991 to one of the first GSM phones, the Siemens P1. Obviously, the Siemens P1 big and heavy but even then it was clear that the next step in miniaturization were real "handheld" devices as shown in this video clip from the 1991 international radio exhibition (IFA) in Germany. One one of the first truly mobile phones was the Nokia 1011, announced at the end of 1992. And here's the TV commercial from back then. Enjoy!

Here is some very interesting information concerning the number of 3G base stations NTT DoCoMo in Japan. According to this report from UnwiredInsight, the company currently has 62.800 outdoor HSPA base stations and in addition 29.200 indoor installations.

These numbers are incredibly high, especially when compared for example to the number of base stations Vodafone says it has in Germany (and provides very good coverage with!). According to reports, Vodafone has around 20.000 GSM base stations in Germany and 13.000 HSPA base stations (I assume most are co-located with GSM). Now Germany and Japan are almost equal in size so the number of base stations should also in the same area. But they are clearly not. So I thought that perhaps what they meant was number of sectors. But no, even NTT DoCoMo themselves have released similar numbers and also says it's "base stations".

Well then, looks like they are not beaten anytime soon in this number game.

If you are a frequent reader to this blog you have probably noticed that I am running Ubuntu on my netbook for a couple of years now as it is fast and slick on such limited hardware and, of course, it's open source. But there are a few tasks for which I still prefer Windows software, for which I use Wine to use it in Ubuntu.

One of these is the Windows TightVNC Remote Desktop Client, which for my purposes is much better suited than Ubuntu's built in Vinagre VNC Client. Especially the "scaling" option that let's me scale down the remote desktop which tremendously helps if it is vastly bigger than the small netbook screen is sadly missing. Also, the built-in client does not show me the local mouse pointer which kills usability as it makes moving the remote mouse pointer precisely very arduous.

But o.k. I use Wine to run the Windows application in Ubuntu and it does the trick, even if the scaled down image of the desktop does not look as nice as if the program ran on a real Windows machine. However, it has its limits, too. When I recently tried to remotely administer another Ubuntu machine with it, I found it to be unstable with Vine as the VNC server on the other end. So I switched back to Vinagre just to be disappointed again by the missing local mouse pointer. Time to do search for an alternative. And the alternative I found is quite stunning. It's called Remmina and can be installed right via the Ubuntu package manager.

Not only does Remmina have a seamless scaling option that beautifully reduces the size of the remote desktop but it also has a full screen view in which the desktop moves when the mouse pointer hits the screen limit in case the remote desktop is still biger even after scaling down. Also, it handles both Windows 7 and Ubuntu client desktops without any hicups. Perfect! Furthermore, it has a reverse VNC functionality, i.e. the remote desktop can establish a connection to the client. I use this quite frequently when the remote desktop is behind a NAT in which the TCP port required for the incoming VNC session is not forwarded. In this case the user of the remote computer needs to establish a reverse connection. Very simple on Windows but unfortunately not built into the Ubuntu remote desktop server Vino. Again a simple fix: After installing X11Vnc from the package repository, a reverse VNC session can be established with a simple command: "x11vnc -connect YOURIPADDRESS". Easy to put in a shell script which is then linked to an icon on the desktop. This way, the remote user doesn't even have to type in anything.

And finally, another very important thing Remmina and X11Vnc do is to adapt to the connection being established over the Internet, i.e. much less bandwidth than in a local network. Compression is automatically activated with a good balance between good looks and speed.

Internet Access in the air is once again in the air, so to speak. A couple of months ago, Lufthansa has restarted their on board Internet access again after a pause of several years. On my way back from New York at the time of this writing, I had the fortune to be one one of the planes with a satellite dish on top. Great stuff and I am posting this from over the Atlantic ocean. Download speeds are in the range of 2.5 MBit/s, although the speed is quite variable. Uplink speed is 500 kbit/s and the round trip delay time is around 700 ms from the position you can see in the picture on the left. Time for some sleep now though, with Internet access or not. Good night.