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Just a quick update for those of you having a spontaneous streak: I'll be at the University of Oxford this week from the 13th to 15th October for the Forum Oxford Future Technology Conference on Friday and of course for my Beyond 3G course on Wednesday and Thursday I give in partnership with Ajit Jaokar and John Edwards. Also, Tomi Ahonen will be there for the conference and his Mobile as the 7th Mass Medium course on the 12th and 13th. In other words a week full of exciting discussions and learning on mobile. Prices for the courses and the conference are, I would say, very reasonable. If you can't come during daytime but would like to meet anyway, drop me an e-mail, I'm sure there's an opportunity for an after-hours pub session somewhere in town. My email address is gsmumts at gmx.de.

And now as a little follow up some somewhat more general telecom observations from my recent short visit in Tokyo.

Mobile Phone Use: According to this reference, Softbank launched the iPhone in Japan back in 2008. And indeed, every now and then I saw someone with an iPhone. To me it semt to be far fewer people though than in other countries. Most people seem to prefer the brick style and long format clamshell phones that immediately give away someone as a Japanese tourist abroad. Other than iPhones I didn't see many touch based phones, it didn't seem to be in fashion (yet?).

3G Notebook Use: 3G USB keys are not yet marketed as agressively as in some European countries where you can buy them for a couple of euros with a prepaid SIM inside and daily, weekly or monthly packages available. But even though they seem to be quite popular here as well. While sitting in a Starbucks (yes, no Sushi…), I saw many people coming and going with notebooks and a 3G dongle of some sort for Internet connectivity. No free or paid Wi-Fi at the Starbucks…

WiMAX: And, quite surprisingly, South Korea doesn't seem to be the only place where WiMAX has been deployed on a larger scale in an industrialized country. There's seems to be a WiMAX network in Japan, too and I saw some pretty heavy marketing for WiMAX to Wi-Fi boxes and notebooks with builtin WiMAX connectivity in electronic stores.

The Fraunhofer FOKUS institue in Berlin must be one of the most busiest applied research centers when it comes to producing interesting conferences in the mobile domain. In just a couple of weeks, from November 4th to 5th to be precise, they are hosting the Media Web Symposium on Mobile Applications, Social Media and HybridTV. Lots of industry players are going to be there and everything from Android Programming to the Wholesale Application Community (WAC) is going to be discussed. Here's the schedule for those of you who want to take a closer look. If you plan to attend, I've been given the a registration code ("WirelessMoves") for 5x 30% discount to pass along. First come, first served.

What do I do on a short stopover in Japan? Right, I check out the 3G networks there. After all, NTT DoCoMo was the first network operator to launch UMTS (FOMA). Also, they have no GSM network to fall back to so they need to think a lot harder about 3G indoor coverage and ubiquitous coverage on trains, etc., so voice calls don't drop. In addition, if the 3G network works well in Tokyo with its high population density there's no excuse anywhere else. And indeed, the network worked very well during my stay and the setup was unlike anywhere else.

On the way from the airport small screen web surfing on my mobile worked just fine and I never lost the network. Also, I never lost the network indoors. In a shopping mall I always had a strong signal and only one cell, so it's likely there was dedicated indoor coverage and no repeater bringing in the signal from outside.

At first, it looked like DoCoMo had only one carrier on air in the Ginza district, as no inter-frequency measurements were configured by the network. But when transferring data, the UE was immediately put on another carrier frequency while it was in Cell-DCH state. I observed two additional carriers. Here, the UE was kept for around 10 seconds after the last piece of data was transferred, a value seen in many other networks as well.

When no more data is transferred, the mobile is returned to the initial carrier and kept in Cell-FACH state for around 90 seconds. Not very energy efficient and much longer values compared to those I've observed in many other networks which range from 10 to 30 seconds. (Hello Fast Dormancy!)

If still no data was transferred during that time, the network sets the connection in Cell-PCH state for around 2 minutes after which the connection is put into the idle state. Again quite a surprise for two reasons. Why a 90 seconds FACH phase when the networks puts the connection in Cell-PCH afterwards? And why only 2 minutes in this state afterwards? I am sure they have their reasons but I can't quite figure them out. Most (of the few) other networks that use Cell-PCH I have observed in Europe so far quickly put the mobile to the Cell-PCH state, for example after 5-10 seconds in Cell-DCH state and a further 5-10 seconds in Cell-FACH state. Afterwards, mobiles are kept there for long durations, 30 minutes not being uncommon. Some networks even use the URA-PCH state if a mobile moves between cells during that time to reduce the amount of required signaling. Quite a different strategy.

Ah yes, and then there are voice calls. I made a couple of calls and they were all handled on the basic carrier.

Softbank also has a 3G network in Japan and it would have been interesting to see what they are doing. Unfortunately, no roaming agreement was in place so my mobile would not roam on that network. Well, next time then…

Here's a press report I picked up recently from Kineto, who've ported their UMA protocol stack and application to Android Froyo. This may sound a bit cryptic but it has interesting implications for Voice over LTE.

For those of you who can't place the term UMA (Unlicensed Mobile Access), it's basically GSM voic calls over Wi-Fi. On the mobile device, all layers of the protocol stack of GSM are reused with the exception of the lowest layers where the UMA software introduces a switch so phone calls and signaling are either using the GSM infrastructure or a Wi-Fi access point that connects to the Internet. For the user its completely seamless. On the network side, the base station and the base station controler is replaced by a UMA gateway controler that connects to the Internet on the one side and to the network operator's core network on the other. To the core network the gateway looks like a GSM base station controler which makes UMA also transparent to the core network, i.e. no software or hardware chagnes needed there at all.

So UMA on Android, what does that have to do with voice over LTE? Well, as you might be aware of, there's no built in voice telephony functionality in LTE. That's why a number of different options have been suggested, one of them being Voice over LTE via GAN, or VoLGA for short. Now GAN (Generic Access Network) is just a synonym for UMA and that already tells most of the story. Volga replaces the Wi-Fi layer of UMA with LTE.

In other words, to close the circle, there's only little work required to modify the UMA Client for Android to use not only a Wi-Fi network but also an LTE network once Android LTE devices become available. With a client available for Android, operator based Voice over IP has arrived in the smarphone space (beyond RIM) and on an operating system that will play a major role in future LTE devices. And the work to make the software work with LTE is almost trivial since both Wi-Fi and LTE are IP based networks. So 99.9% of the software don't care if Wi-Fi or LTE is used for the transport of the IP packets that contain the speech data of an ongoing voice call.

One additional thing that requires a bit more work is the handover of an ongoing voice call from LTE to GSM (or UMTS) when the user is at the coverage limit of the LTE network. But like UMA, which is a 3GPP standardized technology, 3GPP also comes to help out here as there are already methods defined to do just that. The functionality is referred to a Single Radio Voice Call Continuity (SR-VCC). Specified in a generic way it can be used for IMS and also for Volga and potentially other solutions in the future.

While it takes a bit of work to implement SR-VCC into Volga, its fully specified and well worth to be done, as LTE – GSM handover of voice calls is a network operator's biggest asset to stay relevant in the voice call domain in the future as over the top voice applications have no way of doing that.

Here I am again in a hotel in the US, the Hilton in San Jose to be exact, and I am glad that I have quad-band 3G stick and the AT&T prepaid SIM with me, as the Wi-Fi/fixed Ethernet connectivity in the hotel just doesn't cut it. Available for 10 dollars extra a day, I just get a meager 150 kbit/s through the line with highly variable delays and packet loss. Even at 3 a.m. (hello jet lag…) the speed is less than 1 MBit/s. No matter how many MBit/s your DSL line is capable of, dear Hilton manager, it's far from enough. We are in Silicon valley, so heavy Internet use should not be surprising!? So I vote with my feet. No money for you for the Internet access, it's gone to AT&T. Not that their 3G network is anywhere close to the best I've seen with the 2 MBit/s I get, but way beyond what comes out of that Ethernet jack in my room. Reminds me a bit of the stick meeting post I wrote some time ago. Let's see how many 3G sticks are used in the meeting today in the US.

Just recently I was, and actually I quite am, quite extatic about having reached 11 MBit/s throughput in a live 3G network over here in Germany. But the specs are already two orders of magnitude ahead.

In a recent 3GPP RAN meeting, a new set of LTE-Advanced UE categories have been specified. The highest one, Category 8, specifies a transfer mode for 1200 MBit/s downlink and 600 MBit/s uplink transmissions. That is, of course, if we'll ever see devices with 8 receiver antennas and networks that have base stations with 8 transmit antennas per sector. Also, a channel bandwdith of 40 MHz is required. Each parameter on its own is already quite a stretch when compared to the current state of the art. But then, only ten years ago, we were creeping along with wireless speeds of just a couple of kilobits per second. Two orders of magnitude less, actually.

For those who want to have a closer here's a link to the 3GPP RAN WG1#62 report. In the report, search for R1-104944.

While I'm personally a bit sad that non of the new Symbian^3 based phones Nokia presented at Nokia World recently is a vertical slider with a traditional T9 keypad there's one thing that makes my international roaming heart jump: All devices presented, namely the C6, C7, E7 and N8 all come with a pentaband 3G receiver included. In other words, while my current single band UMTS device has to fall back to GSM when roaming for example in the US or Canada, these devices should work pretty much everywhere you go. Also good for Nokia as that significantly reduces the number of device variants. For details here are the product pages for the N8 and E7.

In some countries in Europe such as Germany, for example, there are quite a number of offers for daily 3G Internet access now in the range between €2.50 to €5.00. Especially €2.50 offers sound quite cheap, almost like network operators giving their services away for free. But how much is that compared to the daily fee of a DSL line at home? Let's compare with a DSL line that costs €30 per month. That would be €1.00 a day. In other words, there's still a premium for wireless in the daily charge. So while it sounds cheap, summing up €2.50 over 30 days brings you to €75. That's quite a sum so it quickly pays to go for a monthly option if mobile Internet access is required for more than just a few days per month.

Every now and then I see in computer magazines or tech websites some network speed measurements (including my blog). Often, however, they are based on single measurement experience or maybe based on using a notebook in a few areas in the network. While this might be good for telling the performance in those places it doesn't really capture the overall capabilities of the networks. For this, so called drive tests are required and for comparisons between different networks, measurements must be performed in the different networks simultaneously. That's quite a challenge but the resulting data is well worth it. Here's a link to a recent article in a the German computer magazine "Chip" that has made an extensive test of the German networks. Google can help to translate the pages for those non-German speakers of you. Highly recommended for the background information and the interesting pictures of the measurement equipment and the results. If you know of similar tests having been published in other countries, please let me know!