Category: Uncategorized

One thing that struck me as very true when reading through the history of Ericsson website was that when making predictions of the future, it is not only one parameter that changes but many simultaneously. This is what makes predicting things so difficult. A prime example is the forecast of GSM subscribers in the mid-80s and even throughout the 90s which were always wrong in orders of magnitude. And an additional difficulty that comes to mind: Knowing which parameters have an influence in the first place. Even if you make assumption about several parameters you could still miss important one for the forecast.

A quick thought today on my most favorite browser on my mobile devices,Opera Mini: While I still prefer Opera Mini on the small screen especially for the daily commute where 3G coverage is at times patchy and I don't want to see the flashy advertisement anyway, using it on a Pad is quite a different thing. Here, the much larger screen is made for viewing full web pages. Mobile pages or those downscaled with Opera Mini just don't cut it there. And as far as removing unwanted advertisement is concerned, the Android version of Firefox works great in combination with the Addblock Plus plug-in already known from the PC.

With the industry now thinking about multimode/unified GSM, UMTS, LTE base stations (see this post from back in 2008) it is likely that as we go forward there will be little incentive to switch-off UMTS because of LTE becoming more prevalent. But just for the sake of the argument: What would have to happen before UMTS could be switched off? The following things come to mind:

• Voice: LTE is rolled out without an operator based voice solution. So one way or another, and there are quite a few, the voice question has to be answered. No matter whether its VoLTE, VoLGA, CS fallback, dual active radio in the phone, over the top internet based voice solution, something must fall into place first as a mainstream solution for simple voice calls. And, it needs to be at least as good as today's circuit switched voice in coverage, call continuity for moving subscribers, in-house coverage, etc.

• Coverage: LTE coverage must be at least as good as 3G coverage today. For voice it must be far better than 3G coverage today.

• LTE Devices: Smartphones not having an LTE chip inside must have become a minority in the network. 

Quite tough requirements. But then, it's not a digital on/off decision. UMTS can be gradually phased out once necessary. Future multimode base stations are likely to be very flexible and bandwidth released from one air interface technology can be moved via configuration changes to another air interface protocol.

The Internet is great when it comes to making information accessible to others and search engines hugely amplify the effect by allowing people to actually find what is offered online. But there is also a catch!

Just go back a number of years on this blog and click on a couple of external links and you will notice that quite a lot of them don't work anymore. Companies restructure their sites, remove interesting information entirely, private web site owners loose interest and sites are shutting down. There is a saying that the Internet never forgets but that doesn't seem quite true to me in this context. Quite the contrary.

Books are on the other end of the scale. Information contained in them can sometimes be hard to find and obtaining books no longer in print is sometimes also difficult. But once you have it, the content is available to you for as long as you want. You and not an external party is in control of when that information goes away.

Don't get me wrong I don't advocate books over the information stored and to be found on the Internet. However when I want to preserve information found on the Internet I no longer only store the link to it but also either print the page into a PDF document (iWeb2Print is a nice service) or get a copy of the page and sub-pages with tools like scrapbook.

Prodding along on the history trail for a moment here, I've got two super interesting links for you today if you care to read up on how GSM and later UMTS where created.

The first link leads to Ericsson History and the beginning of the 1980's. Rather than just plain facts, the subsequent pages also name the key players, their thoughts and the strategy behind it all from an Ericsson point of view.

And the second link leads to Stephen Temple's GSM history page which describes the things that happened from his point of view, working in the UK's department of trade and industry (DTI) who was one of the main drivers behind the creation of the GSM Memorandum of Understanding that was signed in 1987.

Lots of things to discover on both pages, enjoy!

Here's something that has repeated a number of times in recent wireless history: As described in an Alcatel presentation from 2006 and confirmed by 3GPP here, the first meeting held on LTE was in November 2004 in Toronto. From today's perspective, 6 years from the first meeting (*) to deployment of first networks in the field is a pretty good accomplishment. What is even more amazing to me is that back in November 2004, I didn't even have a UMTS phone yet, I only bought my first one in December that year. Networks where only at the beginning of their rollout and mobile devices were still rare. In other words, most people in that meeting at the time also didn't have a UMTS phone. And yet, they were already thinking ahead about what will come after what they didn't have yet.

(*) there were investigations before that meeting of how OFDM could be used to extend 3G but these activities concentrated on the air interface only from what I can tell.

We've come to a point at which advanced baseband chipsets and transceiver frontends support pentaband UMTS (e.g. most of the current Symbian^3 based devices such as the Nokia N8, C7, etc.). In other words, global UMTS roaming is now finally ensured with 900 and 2100 MHz bands used in Europe and elsewhere and 850, 1900 and 1700/2100 MHz bands in North America. But with LTE the story repeats itself all over again. In Europe three bands are currently used for LTE deployments, namely the 800 MHz digital dividend band, 1800 MHz and 2600 MHz. In the US, the 700 MHz band is currently used for LTE by Verizon. However, there is one band the two regions have in common, the 2600 MHz band (LTE band 7). Unfortunately at the moment the use is different. While in Europe band 7 has been split up between several carriers in those countries who had auctions recently, the band is almost in full possession by Clearwire in the US. And Clearwire is using TDD WiMAX in the band exclusively. However, they are thinking about jumping on the LTE bandwagon and a trialing both the TDD and FDD flavor of LTE (see here). So imagine what would happen if Clearwire would start adopting the FDD flavor of LTE in that band. It would mean that for the first time there is a single band that is used with the same technology worldwide, except, perhaps, Japan. Not only would it be good for international roaming but Clearwire would instantly have access to any devices produced for the European market. In wonder if it will happen, I guess it could go several ways.

Here's a picture I've taken on a recent visit to New York that shows an interesting antenna installation. Instead of being installed vertically and aimed at street level, this antenna is installed horizontally and directed upwards across the street and up a skyscraper. It's not everyday that I see something like that. I wonder if this is the default way to beam coverage into skyscrapers in New York or to what degree dedicated inhouse coverage is used. Anyone?

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!?