Author: Martin

UMA For Android Shows How Easy Voice Over LTE Can Be

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.

When the Hotel Wi-Fi Just Doesn’t Cut It

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.

Be prepared for 1200 MBit/s with LTE-A

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.

Pentaband UMTS Phones from Nokia

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.

How Much Does The DSL Line Cost Per Day?

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.

Panopticlick and Online Privacy

I prefer not to be tracked by ad-networks and other 'services' on the net and so far thought I was pretty much o.k. with having my cookies deleted whenever I end a browser session and having flash cookies disabled by default. But now it seems this is not quite the case.

Have a look over at the Electronic Frontier Foundation's (EFF) Panopticlick project and run the test yourself. By analyzing the user-agent information the web browser gives the web server when it connects together with additional information that can be queried and returned by JavaScript and Flash content embedded in a page, it is in most cases possible to uniquely identify you again. Yes, uniquely, as the combination of browser version, available fonts on the system, their reported order, time zone, screen size and a couple of other parameters generates such a wide range of combinations.

When running my browser as it is, my PC is identified as unique among 1.2 million devices already tested. If I activate No-Script to prevent JavaScript and Flash to execute on that page, the detection rate is down to 1:6815 devices. Still a shocking number. And if you add my German IP address into the mix in combination with the browsers language set to English, the whole thing probably blows up again.

Pretty solid research from the EFF and I hope we come up with some browser plug-ins soon that randomly change some of this information from time to time to protect my privacy.

Network Drive Testing

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!

The D-2 Story

D2 Most of us still remember in one way or another how the telecoms world looked like 25 years ago in Europe, North America and many other places around the world: State owned companies still controlled the voice telephony and data transmission market in many parts of the world and they had a monopoly for everything up to the last centimeter of the line, including the cable up to the actual telephone. Nobody but them touched any part of the network, there was no competition, and prices were in ranges that sound unbelievable compared to today. A lot has happened since then not only on the technology side that regularly spits out a new generation of equipment that is by orders of magnitude cheaper, faster, smaller, less power hungry, etc. But this is only one side of the medal. The other was privatization, i.e. the end of telecoms monopolies and regulation of telecom markets to ensure a fair and thriving competition between the former incumbents and those who've just entered the market.

A couple of weeks ago I wrote a post on this book on the inception and evolution of SMS which gives an interesting account not only on this topic but also how GSM as a whole was developed in the 1980s. While reading this book I remembered another book on the topic I read many years ago, “Die D-2 Story” (only available in German). Written in 1994, it gives an account of how the liberalization of the telecoms market in Germany started at the end of the 1980s by allowing and fostering a second GSM network operator next to the state owned incumbent. Reading the book is a sort of double history because Susanne Päch describes the events as seen in 1994. Now, over 15 years later, one can see what has changed since then and how the story continued, again from a technical and also a political point of view. Both histories, the one up to 1994 and the one afterwards are nothing but stunning. Here are some of the most outstanding events in those 25 years described in the book and also later on that I remember myself:

End of the 1980s: Germany decides to liberalize the telecoms market and start with mobile networks. The model for the process was the UK, where privatization started somewhat earlier.

A competition was launched to find the best private consortium. In the end, the winner was Mannesmann Mobilfunk (later bought by Vodafone), a consortium driven by the company of the same name but including many other companies. The book gives incredible details on the political situation and the developments inside the former incumbent, in the telecoms industry that developed the equipment and in the companies vying to win the second GSM license.

Getting from the state of the industry in the 1980s to today required many iterations. Even in 1994, when the book was written, the author could probably not have imagined how a fully liberalized telecoms market that we have today would look like. But I think that is not surprising. Just imagine how closed and nationalized the markets were prior to GSM. Here's an example: If you were one of those few thousand people who possessed an analog wireless telephone in the trunk of your car special actions had to be taken when crossing a national border. There may have been some exceptions, but by and large, the analog wireless phones could only be used in their country of origin. As radio waves don't stop at national borders some countries enforced deactivation by sealing the device and checking the seal on departure again. Others insisted that the owner attach a note at the device that it was forbidden by law to use the phone in their country. And yet others required the owner to pay a fee when they brought their phone in the trunk along. Those were the days… hardly imaginably today anymore when we already get upset if the phone needs a bit longer to find the network when it is first switched on in another country.

Prices both for fixed and mobile telephony slided significantly from then to now. Here's a recent post that looks at how prices have changed during the last 10 years.

While back in 1994, only mobile communication and microwave transmission to backhaul the traffic from the base station was liberalized, 1998 saw the liberalization of the complete telecoms market including voice and fixed line backhaul. Also by that time, four mobile network operators compete in the German market.

I could go on and on but suffice it to say that if you speak German and are interested in telecoms and its history, this book gives an incredibly interesting insight in those crucial years at the end of the 1980s to the first commercial availability of GSM by two network operators. As the book was written in 1994, it is no longer available from the publisher but you can easily find it on eBay and other sites that offer used books.

To close, here's a link that contains interesting information on the history of telecoms and wireless in Germany (again only in German) for a much longer period. Similar things like in Germany pretty much happened in all European countries in around the same time frame, give or take a couple of years. And yet, the differences made then still influence the markets today and the situation in the different countries is still diverse today. Compare Austria with France and then with the UK for example. Is anyone aware of similar books that describe the evolution of telecoms in other countries? I'd be highly interested to have a look!

3G Internet Access for 13 Euros in Italy

It's good to see that the number of prepaid SIM offers in many countries that can be used for 3G Internet access keeps going up and the Prepaid Wireless Internet Wiki keeps growing and information is constantly updated. Also, I keep noticing that prices are getting more competitive. For my two weeks of vacation in Italy this summer, for example, I used a SIM card from mobile operator WIND which I already used during previous trips and noticed that prices have further gone done. For my two week stay, the 1GB / month data option was quite sufficient which now only costs 9 Euros + a 4 Euro activation charge. For longer stays the 10 GB / month option for 20 euros might also be an alternative. Compare that to what some hotels charge for Wi-Fi per day…