Martin – Page 246 – WirelessMoves

SIM Cards on a Boat Ride

I recently took a trip over the English channel from Calais to Dover on a P&O ferry and noticed the vending machine shown in the picture on the right from which passengers can get English SIM cards from different operators for their time on the island. Since no registration is required in the UK when buying a SIM, it is already activated and can therefore be used right away.

Note that only UK operators were offering their SIM cards in the machine, French SIM cards were nowhere to be seen. This could be because the ferry was operated by an English company or maybe because identification is required when buying a SIM card in France. Maybe it's also due to the lack of real competition in the wireless market in France. Hard to tell.

However, upon my return to France, I noticed that in some train stations and also in some supermarkets, Virgin, a MVNO using Boyugues' GSM network sells 'mobile phones to go'. The box says they can be used right away but a copy of the passport has to be sent to them within 7 days. The text on the box also suggested that topping up the account might also only be possible once the registration has been processed. I wonder if that is a creative way to comply to government regulations or to ensure people send in their details.

Anyway, I hope that SIM card vending machines do make it into other places such as airports as well, it would significantly reduce the effort to get a local SIM card for mobile Internet access when arriving in a country.

Evolved EDGE Whitepaper by 3G Americas

Over the past 2 years I've written a number of blog entries on Evolved EDGE (here, here, here and here). Now that the feature set is mostly specified, vendors are moving into the implementation phase. A recent whitepaper of '3G Americas' is giving an interesting overview of the different features (without going to much into the implementation details), their potential, and different likely implementation phases. I quite like the paper as it takes a look at EEDGE not only from a technical but also from a deployment point of view.

From a technical point of view the paper mentions one thing in particular which I have not thought about before, and that is that there are two improvements brought by the dual carrier feature. The first improvement is that it improves throughput because timeslots can be assigned simultaneously on two carriers. That's quite obvious.

The second improvement is that even if some timeslots are busy on one carrier for voice calls, the same timeslots on the second carrier might be free and can thus be assigned. This doesn't result in the full theoretical speed but at least compensates for the fact that it is difficult in many situations to have 5 timeslots in sequence available on one carrier. In effect this statistically increases the number of timeslots available for a dual carrier mobile compared to a current single carrier mobile and thus increases the overall speed experienced by a subscriber by using timeslots that could otherwise not be used.

Internet For The Other 3 Billion

Heise News reported recently about O3b Networks, a new satellite operator who’s mission statement is to connect “The Other 3 Billion” to the Internet. Hence, their name O3b. It was probably worth a post as one of the investors is a certain Google Inc. The company’s web site doesn’t yet contain a lot of material but what they’ve already put there makes some interesting reading. Heise reports that the company aims to put 16 satellites built by Thales Alenia aerospace into orbit with a total of 2300 transponders. Each transponder has an uplink/downlink bandwidth of 216 MHz, which delivers a throughput of 600 MBit/s in each direction. The company targets fixed line and mobile networks in the developing world for backhaul services and says there system is designed for significant savings over previous backhaul transport in regions where laying a fiber is no option. It would be interesting to get some hard numbers in terms of dollars per month. Latency of the system is given at 65 milliseconds, quite important for real time services such as voice and interactive services such as web browsing. The company also positions itself for emergency scenarios and says they can get bandwidth to any place around the globe +/- 45 degrees of the equator within 10 minutes. The satellites have yet to be brought into orbit which is foreseen around 2010. An ambitious and exciting project!

The Line Is Busy But You Don’t Notice

I recently surfed the web with my Nokia N95 over my home Wifi network using the OperaMini browser while simultaneously downloading a movie from my online video recorder at the full DSL line speed (7 MBit/s). What quite surprised me was that despite the line being 100% busy because of the file download, the browsing experience on the phone was perceptively not slower than if the DSL line was not used at all.

There are a number of conclusions that can be drawn from that:

It shows the huge difference in bandwidth requirements of different applications and due to the little bandwidth requirements of one application the user does not even notice that a network with a significantly higher bandwidth is already fully loaded.

From a technical point of view mobile web surfing with compressed page downloads costs almost nothing compared to the transmission costs incurred by other applications such as huge file downloads and full web browser use.

The situation obviously changes when even small screen devices download full web pages including high resolution images. Mobile web browsers such as Opera Mobile, the Nokia N- and Eseries web browser and the iPhone already do that today. However, for most web pages the experience is not as good not only due to the high amount of data that has to be transfered but because the processor is not being able to render the page as quickly as on a PC. Over time, this might well change but I guess there is still a lot of time left where the OperaMini compression approach will deliver suprerior results in most cases.

3G FACH capacity

With the rising number of push eMail devices in 3G networks and mobile applications such as instant messengers and voice over IP clients the number of small IP packets to keep the connections of such applications alive through network address translation routers is rising. For the network this means of lot of radio layer signaling and waste of bandwidth. For the mobile device, keep alive messaging means significantly increased battery consumption.

3G UMTS networks are thus putting devices that only send little data on the Forward Access Channel (FACH) which requires much less radio channel signaling overhead than if the device is instructed to remain or use the High Speed Downlink/Uplink channels for such kind of traffic. As more always-on devices are used in the networks, this will quickly become an issue since the total capacity of the FACH of a cell is limited to 32 kbit/s today. With the bandwidth so small I think most operators will be very thankful for the enhanced-FACH extension which reserves some capacity on the high speed downlink channels for FACH operation. Despite using the high speed channels, no additional radio layer signaling will be used so overhead and battery consumption remains limited at the expense of spectral efficiency. While networks and mobile devices do not support this feature today I expect that this is definitely a feature that will be implemented in the future.

For more on radio interface optimization for future devices and services have a look at my previous entries on continuous packet connectivity (here, here and here), some more background on enhanced FACH (here) and some thoughts on upcoming capacity issues due to keep alive messaging (here).

It seems there is now also an initiative in Release 8 of the 3GPP standards to improve the uplink behavior of the system while a device in in Cell_FACH state. More about that once I have taken a look at the details.

RIM’s European Advertisment Campain for the Young and Cool

It's interesting to see how RIM attempts to push their Blackberrys beyond their core market, email business users, and how it advertises the new models. It's funny when you come across the same poster in different countries in different languages, it's almost like a deja vu. Below are two examples of the same poster, one from the U.K. and the other from Italy.

While Michael Mace says RIM is not in the same market as Apple except for some overlap, it seems to me that this overlap is not that small anymore. With their campaign they are definitely trying to increase the overlap, just as Apple tries to add functionality to appeal to business users to increase the overlap in their favor.

I think even before this advertising campaign, RIM has already moved beyond the typical business user anyway. When I was in the US recently, I saw lots of definitely "non-business" people carrying a Blackberry. Maybe that's because there is not a lot of choice. In operator stores, there was the iPhone, a couple of Blackberry variants and a couple of very low end phones. Nothing much in between.

Why Are We Still Using Narrow Band Codecs for SIP to SIP Calls?

I really like the SIP Voice over IP implementation of the Wifi enabled Nokia Nseries phones such as the N95 and the N82. After all, they save me a lot of money these days as SIP to SIP calls for example even between different operators are free. On first thought, voice quality seems to be excellent, I can't tell the difference between a VoIP call and a traditional circuit switched call over a cellular network. But put into a different perspetive, that's a bit short sighted. For direct SIP to SIP calls that do not cross a circuit switched interface, why do the two SIP clients still use the backwards compatible G.711 narrow band voice codec released in 1972 or the narrowband AMR (Adaptive Multi Rate) codecs? Today, much better codecs such as Wideband AMR (AMR-WB) are available that have a similar audio quality as Skype to Skype calls. So why are we still stuck with a narrow band encoding? It can't be computing power, especially in the case of high end Nseries phones. Maybe license or patent issues? Ideas, anyone?

SIP providers miss a great opportunity to go beyond the limitations of circuit switched networks and offer subscribers a superior experience for direct VoIP to VoIP calls. And I think it would be a good selling argument once suddenly for some connections you have a much better audio quality than to someone still stuck in the circuit switched world (or in a SIP network that is not interconnected and thus has to use a circuit bridge). I can very well imagine that at some point conversations would start with "oh, you are still on an old phone line" 🙂

P.S.: Some details: The N95 SIP client supports AMR, G.711 a- and my-law, iLBC and G.729. All narrowband…

Connecting Back Home

For many years I’ve wished for some technology to allow me to check on things back home, to control devices and to stream content from wherever I am. Some applications have become available over the years such as the GSM module that is connected to my block heater in the car so I can remote control the heating in winter. The Slingbox is another good example which allows media streaming to notebooks and mobile phones outside the home network. But such applications are still the exception rather than the norm.

In the recent Ericsson Review, I found an interesting article that gives an overview of current activities in the industry and standardization bodies concerning this topic. Noteworthy standards, bodies and activities mentioned are the Digital Living Network Alliance (DLNA), UPnP, UPnP Remote Access. Ericsson says while this is a good start, the solution lacks good remote connectivity. While UPnP provides for an encrypted tunnel that can be established between a notebook or mobile devices in general to access resources in the home network from outside, it lacks Quality of Service (QoS) interaction with the outside network and requires devices to be authenticated in the home network of the user once before they can be taken outside.

Ericsson sees a solution for this in using the IMS (IP Multimedia Subsystem) as a secure way to authenticate external clients, to exchange ciphering parameters between the home network and the remote client and to ensure QoS of the transport network for media streams.

A good starting point to dig deeper into the topic!

Beyond 3G: The Manuscript is Ready

Some of you might have noticed that recent blog entries haven grown in size again and speculated that I have a bit more time at hand again. Well you have guessed right. Over the past months, I spent most of my free time working on my next book, to be published by John Wiley and Sons by the end of the year. Finally, the manuscript is ready and the title will be

"Beyond 3G: Bringing Networks, Terminals and the Web Together"

For the moment, people at Wiley's are now working on the cover, they are proof-reading the manuscript, and typesetting is starting soon. After that, I'll have to work a bit on the index, on the glossary, etc., etc. But that's a bit later in the year. I always find it amazing how many steps are necessary from finalizing the manuscript to having the finished book finally being shipped to the bookstores.

It's a long process. However, I strongly feel that all of this work is necessary and justified to produce something outstanding that has something which is missing in day to day online publishing: Depth and broadness.

That doesn't mean that online sources are less valuable, they are just different. I very much like my blog for example, because it catches spontaneous thoughts, thoughts about a clearly defined single topics, ideas, it's great for posting the latest news, for responding to someone else publishing something, and it is thus a great complement to my offline writing activities. Together, online and offline are hard to beat!

So what exactly will the book be about? Here's the current version of the back cover text:

Giving a sound technical introduction to 3GPP LTE and SAE, this book explains the decisions taken during standardization while also examining the likely competition for LTE such as HSPA+ and WiMAX. As well as looking at next generation network technologies, Beyond 3G – Bringing Networks, Terminals and the Web Together describes the latest mobile device developments, voice and multimedia services and the mobile web 2.0. It considers not only how the systems, devices and software work but also the reasons behind why they are designed in this particular way. How these elements strongly influence each other is discussed as well as how network capabilities, available bandwidth, mobile device capabilities and new application concepts will shape the way we communicate in the future.

Examines current and next-generation network technologies such as UMTS, HSPA+, WiMAX, LTE and Wifi
Analyses and explains performance and capacity in practice as well as future capacity requirements and how they can be fulfilled.
Introduces the reader to the current cellular telephony architecture and to voice over IP architectures such as SIP, IMS and TISPAN
Looks at mobile device hardware and mobile operating system evolution
Encompasses all major global wireless standards for application development and the latest state of the mobile web 2.0

As I said above, it's going to take until the end of the year until the book is finally shipped. If you would like to be informed when it's available, please send an eMail to "gsmumts at gmx.de", I'll be happy to keep you informed.

Opera Mini on Entry Level Devices

Today, a friend showed me Opera Mini on his new 'Nokia 3110 Evolve', an entry level phone with supposedly a slow processor (compared to Nseries phones) and a screen resolution of 'only' 128×160 pixels. Since he's using OperaMini it was a good opportunity for me to find out how practicable web browsing is on this phone compared to higher end phones. After upgrading from the default OperaMini 2 to OperaMini 4, the browing behavior is the same as on my N95 including the overview mode and zoom in functionality. Concerning browsing speed and scrolling through the page I didn't notice any uncomfortable delay after pressing a button. Even scrolling quickly through a long page is very quick as well. I didn't quite expect such a smooth behavior. Great stuff, kudos to both Nokia and OperaMini!