Category: Uncategorized

One of the things I noted on a recent vacation was not only how many people these days use their camera phones to take pictures but also how many people are now carrying dedicated cameras again. No, not the small point and shoot ones, the big SLR type cameras, heavy as they are. Interesting that now that camera optics and software have become so good on mobile phones to replace an extra camera people are willing to carry heavy and big cameras for the extra quality (or just for the zoom and night shot capabilities?). Agreed, SLR cameras are now cheaper than ever but it doesn't make them any lighter to carry.

I've been in Rome recently for a week and I noticed that on Vodafone and TIM's 3G networks the experience on my mobile phone was quite bad. Quite often when clicking on a link the page would not load in any reasonable amount of time. When switching to their GPRS networks page load times with Opera Mini where good so my problem likely resulted from some air interface issues. On Tre's 3G network, my device performed flawlessly so they must do something different to Vodafone and TIM. To see where my problems came from I therefore decided to take a closer look at how the radio network state changes where configured. Here's the result:

TIM:

DCH timer: < 5 s
FACH timer: 75 s
Final state: idle

Vodafone:

DCH timer: < 10 s
FACH timer: 45 s
Final state: cell-pch

Wind:

DCH timer: < 3 s
FACH timer: 75 s
Final state: idle

Tre (3IT):

DCH timer: < 5 s
FACH timer: 60 s
Final state: idle

When compared to network settings in other countries such as Germany, for example, I was quite surprised about the very long FACH timers. In Germany, those timers are much shorter, and in the range of 15-20 seconds to conserve battery power in mobile devices. Beyond 30 seconds, they are a huge energy drain and really, Fast Dormancy is a mandatory self defense mechanism against such settings…

Concerning Fast Dormany, I am at a loss when it comes to Vodafone Italy's settings. Why is there a 45 seconds Cell-FACH phase when the network then transitions to Cell-PCH instead of Idle. Cell-PCH combines the advantages of low battery consumption with fast data transfer resumption with less signaling in the network to reestablish the connection so such a long Cell-FACH phase seems very unnecessary (for details see the Fast Dormancy link above).

On Wind's network I found the Cell-DCH timer of 3 seconds or perhaps even a bit less quite surprising. In practice this means that the connection frequently changes between DCH and FACH, resulting in an inferior web browsing experience, as each time the state is changed, the transmission is interrupted and packets have to be queued. I noticed this when surfing on my pad as pages loaded much slower than they usually do, especially if they contained content that took a bit of time to be downloaded. Wind as furthermore set the thresholds in a way that the DCH is not kept if only little data flows. So a default "ping" will not keep the connection in DCH state. Only a ping packet size of around 500 bytes had the desired effect. Again, I am wondering why they are doing this!? Are they having problems with the number of concurrent connections in DCH state? It surely can't be to conserve power on the UE side. Time to buy some more DCH licenses guys instead of crippling the performance of your network!

While all of this is very interesting it does not explain why web pages are often not correctly loading after pressing a link on Vodafone and TIM. I therefore suspect that it has something to do with the UE and networks having an interoperability issue when changing between the different states and/or perhaps carrier frequencies, since both have two 5 MHz carriers deployed. Difficult to tell without a deep drill down. So during my stay, Tre.it became my favorite roaming network in Italy and I am glad about manual network selection.

Quick tip of the day: If you are into classic books and want to read them on a tablet/pad/mobile you can of course always download them via one of the dedicated ebook stores and use their proprietary reader apps. But there's also an open alternative, as many of those classics are available for free in PDF or ePub format due to the expired copyright via the Project Gutenberg website. And with reader apps such as "Cool Reader" for example, I find the reading experience quite enjoyable.

A couple of weeks ago, first reports emerged that Google is in the process of offering an offline component for their great maps application. This was at first great news to me as one of the things that keeps me with Symbian is the availability of Nokia Maps and navigation that can be used in full offline mode with maps of full countries and continents downloaded to the device in advance. Anything else is simply not affordable with steep data roaming tariffs. After Google's latest maps release with offline capabilities, however, I am quite disappointed. Only strips of 10 by 10 miles can be downloaded for offline use and no car navigation is possible even within this limited area as reported by the NY times here. No good for me.

Unwired Insight recently reported about interesting projects going on at the moment for the crowd to report on cellular network coverage:

The first one is a project by the BBC to get an independent view on the network coverage of the networks in the UK. It's based on an Android App that takes coverage readings in the background and reports them back to a central server in the network.

The second project is more global in nature and is called Open Signals Maps and aims at mapping wireless coverage globally. Like the BBC approach it also uses an Android app that runs in the background. The results can be seen immediately on their website. I had a go for a number of places all over Europe I am about to go to in the next weeks and found that for each, data already exists. A great tool for travelers, especially when visiting small towns in the countryside to see if there is good 3G coverage available or only 2G and from which network operator.  Also it spares one the trouble of looking for coverage maps on individual network operator web sites, if they are available there at all.

What both approaches are not saying, however, is who the collected data belongs to? To the community reporting in or to the companies running the project?

If the data behind the maps frontend is available it might also be an interesting pool of information for national telecum regulation bodies and IT/consumer publications to compare different national networks with each other, to compare network deployments of different countries with each other, etc. etc. 

 

Back in 2009 I was doing a post in three parts on the LTE core network and noted that so far I did not look into the details of "Idle State Signaling Reduction (ISR)" which sounded interesting but was optional. Now it looks like Zahid over at the 3G4G wireless blog has done it for me and has produced a great writeup of how the tracking and routing area updates that happen when the UE switches from LTE to UMTS or GPRS can be reduced. Also, have a look here at what Santosh from over at "Wired and Wireless" has written about it some time ago.

ISR is good for both the UE and the network as the former does not need to spend power on location updating and the later has a reduced signaling load. In summary, ISR is activated the first time the UE moves from LTE to UMTS or GPRS and performs a routing area update. If the network is ISR capable, the context in the LTE network with the MME is kept and a new context in the UMTS/GPRS is created. Paging for incoming packets while the UE is in idle is then performed in both radio networks.

One thing I haven't yet figured out from the description is if ISR also has a CS fallback component, i.e. whether an incoming call or SMS is also paged in LTE and GPRS/UMTS. Again, something that remains to be investigated when time allows.

It's a bit strange but lately I seem to select hotels that do not have power plugs close to the bedside. Even newly renovated ones!? Another one of those must have's in hotels these days for people owning smartphones that need to be recharged over night due to constant use during daytime. My Nokia N8 has a built-in battery so I had to get an external rechargeable battery for days with heavy use while on the go. I seldom use it for this purpose as the battery usually lasts and I always saw it as a disadvantage to just carrying a spare battery to be inserted when the need arose. But lately, with no power socket being found close by over night, the external rechargeable battery has become the ideal solution. Recharge the phone with the external battery over night and recharge the external battery somewhere else during daytime. Interesting lesson that what is first perceived as a disadvantage can turn into the opposite.

With Clearwire now having officially announced that they will be using the TDD flavor of LTE in the 2.6 GHz band it once again becomes very clear that the strategy of US carriers is to require tailor made devices even on the LTE side of live.

Not that Clearwire could have also chosen the FDD variant of LTE in that band which is already used in Europe by ALL carriers in the frequency band with all the spectrum they are sitting on. I fail to see the advantages of that for everybody involved, the carriers, the device vendors and the customers.

On the one hand, carriers depend on manufacturers to produce specific devices for them so I wonder in what kind of bargaining position that leaves them in. On the other hand, device manufacturers can't get a similar economies of scale for custom made devices than for devices they sell in regions such as Europe, where all carriers use the same set of frequency bands. Unless of course they start building multi-radio-mode devices for the US as well that work across different technology and frequency ranges. Not impossible but I haven't seen one yet.

Let's compare: A future LTE device for Europe has to support the following frequency ranges and technologies:

• GSM in 900 and 1800 (+850 and 1900 MHz for US roaming)
• HSPA in 900 and 2100 MHz (+850, 1900 MHz for US roaming (+1700/2100 for T-Mobile US depending on the outcome of the AT&T merger))
• LTE in 800, 1800 and 2600 MHz (+ roaming?)

That's the setup and applicable for all network operators in Europe, including global roaming to the US and Asia, including China.

And here's the list of bands/technologies for a device that would support all carriers in the US in a world without the merger of T-Mobile US and AT&T. Such a device would give the consumer the choice to pick the device and the network operator independently in the same way as in Europe:

• CDMA in 850 and 1900 MHz for Verizon and Sprint and other small CDMA carriers
• GSM in 850 and 1900 MHz for AT&T and T-Mobile
• HSPA in 850 and 1900 MHz for AT&T and T-Mobile
• HSPA in 1700/2100 MHz for T-Mobile (without the merger with AT&T, who would probably put LTE in here perhaps rather sooner than later).
• LTE in 700 MHz for Verizon
• LTE in 700 MHz for AT&T with an upside down uplink/downlink compared to Verizon
• TD-LTE in 2600 MHz for Clearwire
• ??-LTE for Lightsquared
• + a couple of roaming options for devices to remain usable outside the US when people travel.

Technologies and frequency ranges are very different between the operators, which is probably the main reason devices don't exist today that span the whole range of network operators. Modern HSPA devices support all three US HSPA frequency bands and in addition the two HSPA bands of the rest of the world so they can at least be sold to AT&T and T-Mobile without modification. But fast forward two or three years and AT&T will require devices to have their 700 MHz LTE band included and in addition perhaps another band such as the 1700/2100 MHz band for LTE should the merger with T-Mobile go through.

In Europe we've had the freedom to select the devices and networks independently since the start of GSM two decades ago. I just can't get my head around a system in which this is not the case and thus severely restricts the choice of consumers and competition.

The only thing that would help to reduce the negative effects of the world having been unable to assign and use the same spectrum ranges and technologies would be a universal radio module adapting itself to whatever it finds in the air. But from what I can see there's not even a prototype of such a thing on the horizon.

Data roaming schemes in Europe start getting a bit more sophisticated as the years tick by and also cheaper bit by bit. This year, my home network operator of choice has introduced data roaming bundles that can be activated by SMS messages. Data connections are then either cut once the included data bucket has been used up or throughput is reduced to the bare minimum, in both cases preventing overcharging and bill shock. Very nice.

One of the offers is 2 Euros a day for 10 MB of data when roaming in a European country. Quite enough for use with Opera Mini, which uses a network side compression server, eMail with limited automatic content downloading (Profimail, K9 mail, etc.) and the occasional GPS ephemeris data download when I start the navigation and mapping application. Not sure, if the 10 MB would suffice if I used a full browser. Probably not.

So for mobile use, that's a price I can quite live with for occasional international traffic. For PC use, however, the tariff is still way too high so I still resort to local prepaid SIM cards with data options for that. The Prepaid Wireless Internet Wiki continues to be an important resource.

Over the past couple of days while traveling in Europe I noticed that quite a number of people still seemed unaware of how much voice calls cost per minute while they travel abroad. In two cases I have heard people saying that they do not accept a call or don't want to call back because that is "so expensive". Looks like the old fears of "euros per minute" instead of "cents per minute" as it is now is stuck deep within the psyche of many people. Not good for anyone involved. The call is not made so people are unhappy and network operators are not making money. A most unfortunate combination…