Martin – Page 247 – WirelessMoves

HSPA State Change Measurements

Last week I did some measurements to get an idea of the time required when switching between different HSPA air interface states. While data is transferred, the mobile is usually in Cell-DCH state on a High Speed Shared Channel. When only little or no data is transferred, the connection transferred to the Forward Access Channel, which is slow but has little overhead for both the network and the mobile device in terms of control measurements and power adjustments commands. If no data is transmitted for a longer duration (e.g. 30 seconds) the connection is put into Idle state. While the IP address is retained, the physical connection between the mobile and the network is severed.

As can be seen in the picture on the left, the round trip time to the first hop in the network of a ping packet is around 100 to 120 milliseconds while the mobile is using a high speed shared channel. While on the slower forward access channel, round trip time increases to 240 to 260 milliseconds. Moving from the high speed shared channel to the forward access channel is relatively quick, it takes around 550 to 600 ms (minus the actual round trip time of the packet itself). Going back to the high speed shared channel takes a little bit more time, around 1000 to 1500 milliseconds.

When using a 3G dongle with a notebook, a connection is rarely set into idle state as there is always one program or another such as an instant messenger, VoIP client, etc., that feels it needs to send a keep alive message to a server in the network before the idle time can expire. Therefore I haven't measured it this time. In the past, I've seen values around 2500 to 2800 milliseconds.

Some say that the effect of this state switching is that web browsing feels a bit more sluggish over HSPA than over a DSL line, which always offers Internet connectivity at full speed without the need of state switching. I use 3G connectivity a lot and quite frankly, while I can feel a difference, it's absolutely no problem to work and live with it.

And here's a quick overview of the test setup: Mobilkom Austria 3.5G HSPA network, a notebook connected via Wi-Fi to a D100 Wi-Fi/3G gateway, connected to a Huawei E220 3G USB stick, HSDPA category 6, no HSUPA.

Europe-wide Prepaid Data Roaming

Here's news on an interesting offer recently started by German MVNOs using the e-Plus network (Simyo, Blau, Alditalk): Since October 1st, their prepaid SIM cards are now activated for data roaming in the EU and a number of other countries. Price per 100kb block is 0.19 euros. While not exactly cheap, it's a 10th of their previous price and a 10th of the price of most other operators around Europe.

I wouldn't use it with a notebook but for small screen web browsing and mobile e-mail reception it sound quite affordable. In the countries they support data roaming outside the EU (btw. Switzerland is part of that list…) the price per 100 kb block is 49 cents. For details, see the Prepaid Wireless Internet Access Wiki.

Recently, I tried the offer with my Alditalk prepaid SIM while in France. The first time I tried, right after the start of their offer, 49 cents per 100 kb block were charged. I sent an eMail to their hotline, asking what was going on and they admited that they have a problem with their billing system and returned the money that they overchaged. When I tried again last week, the billing system was fixed and the proper amount was charged.

Uplink Downlink Ratios Revisited

I've been traveling for two weeks now in Austria and Italy and have been online throughout that time 'only' via 3G to do my daily business thanks to prepaid 3G Internet access. Wherever I went, 3G HSPA access has been available so using the Internet with a 2 MBit/s downlink on average didn't feel much different from using DSL at home. I've reset the data counters on my N95, which I used as my 3G modem during the trip, to get an idea on how much data I exchanged. In the past seven days, I used about 750 MB in total for e-mail, web browsing, company Intranet access, VoIP, IM, etc.

As can be seen on the picture on the left, my uplink to downlink ratio is around 1:2 and not 1:10 as I observed during a previous trip. That's probably got something to do with the fact that this time, I received and sent many e-mails with massive file attachments (those 5 MB PDF or PPT files everybody likes…) and have been using VoIP extensively for lengthy conference calls. With VoIP, the uplink / downlink ratio is 1:1 and generates around 20 MB per hour in each direction.

From a network point of view a 1:2 ratio means that I used about as much resources in the uplink as I did in downlink, since uplink transmissions are less efficient than those in downlink due to the smaller antenna and little transmission power compared to a base station. While in most situations, I could get uplink speeds of around 400 kbit/s, which is almost as fast as the uplink of my DSL line at home, I nevertheless wished I would have had a High-Speed Uplink Packet Access (HSUPA) capable device and network. Those 5 MB Power Point presentations do take quite a while to get transmitted.

Yes, one can never have enough bandwidth 🙂

3G Connection Sharing – Part 2: My Fritzbox DSL/Wi-Fi box speaks 3G now!

Recently, AVM, manufacturer of the 'famous' Fritzbox ADSL2+/Draft-N Wifi router, released a beta software that adds Internet connectivity via 3G USB keys to their router software. I really like this box as it's crammed full of features such as a DECT base station, SIP capabilities, meaningful status reports, Wi-Fi interference monitor, DSL line visualization, etc., and now also 3G capabilities with an external 3G modem.

While it wouldn't work with a Huawei E160 3G USB stick, I managed to get it working with a somewhat older E220. The software is still quite an early beta and the GSM/UMTS configuration page in the router is not updated correctly once the connection is established as it remains in the "trying state". Nevertheless the connection is established and the main configuration screen properly shows the IP address and connectivity state. The throughput is the same as if the stick was connected directly to the PC.

Kind of an inverse 3G femto cell and great for traveling when more than one person or device needs Internet access or in areas without DSL coverage. For traveling, however, a somewhat smaller configuration, e.g. a 3G stick in combination with a D100 is probably preferable. For most users, such a setup is probably a lot more practical than the 3G Internet connection sharing via a PC, as I described a long time ago in this post.

Polish 3G operator Play targeting Roamers for Mobile Broadband

It's fascinating to see how new ideas are emerging in different countries to market prepaid SIMs for Mobile Broadband Internet access. The latest and greatest I've seen to date comes from Polish operator Plus. Not only do they offer prepaid mobile Internet access, they even have English instructions on the sales package to make it easy for inbound roamers to use their service. I haven't seen that anywhere else yet. Details can be found here. Thanks to Chris_M for putting the information into the Wiki!

The Book Cover is Ready

Good news from the book writing project! After I delivered the manuscript to the publisher back in September, it has now been typeset, i.e. put in form and shape as it will appear in the finished book. Also, the front and back cover are ready now and the picture on the left shows how the front cover will look like. I have to say that I am very happy with it, in my opinion the colors and the images have been very well selected and integrated.

Only little work remains to be done now and then it will finally go to the print shop.

Here's the text from the back cover:

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

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

If you would like to be informed when the book becomes available and haven't already done so, please send your e-mail address to gsmumts at gmx.de and I'll be happy to keep you up to date.

You can now also pre-order it at Amazon if you live in the U.S., UK, or Germany.

Asynchronous Communication – Why I like Instant Messaging

Despite having been quite a skeptic a couple of years ago when it came to Instant Messaging (IM), I have realized these days that I have fully integrated IM into my working and private life and today I wouldn't want back. In fact, if somebody calls me on Skype these days without sending an IM first to ask if I am available or to let me know what it is about, it feels a bit strange, almost like an intrusion.

Communicating with IM people

I usually don't call people on the phone that regularly use IM. In most cases the questions I have can be answered in a few words. No need to call and 'hard interrupt' the other person or myself. To me, IM seems more like a 'soft interrupt' with the option to ignore for a little while to finish something else first. I can even continue my work and once I have the answer I can quickly go back and fill in the gaps, if the task at hand permits.

While the amount of incoming and outgoing messages remain reasonable, I can get answers and answer questions myself pretty much on the fly without fully interrupting the main task I am doing at the moment. Much more efficient than making a phone call for both parties involved.

I can also see right away when somebody is busy or not available. So instead of calling and leaving a voice mail, I can set a 'notification event' in my messenger so I don't have to guess when the other person might come back or waste time in trying to call.

Communicating with Non-IM people

Seeing people being present gives me a sense of connectedness and the reassurance that I can quickly get help or advice when necessary. With people that are not connected, however, my business practice is quite different. Here, the only way to contact them is by phone or e-mail. While e-mail is definitely less intrusive than IM, you never know when the other person reads it or when he will answer it. And making a phone call will definitely interrupt whatever the other person is doing or I might not be able to reach him at all. It feels a bit like walking in the dark or playing the lottery.

No mobile-IM yet

What I haven't come around to using yet is IM on my mobile phone. Not that it's a technical issue, there are enough mobile IM clients available. Maybe that's because I also don't read my business e-mails on a mobile device since my questions and answers I get/send by e-mails are usually longer than what small keyboards, screens and not being able to look up things in documents, support. Or maybe I just don't want to be bothered while in transition!?

Interesting though how many of my friends, co-workers and customers are using mobile-IM these days, even those that generally questioned the usefulness of Internet access from mobile devices a couple of years ago.

So my question to you is: How do you feel about / use IM today?

P.S.: Have you noticed that almost everyone now uses an avatar (picture) in their IM program. I wonder how that happened!?

Bye Bye ATM

While ATM is used as a transport technology in backhaul and core networks for UMTS and ADSL today it looks like the technology is pretty much on the way out in next generation networks. In LTE for example, ATM no longer plays a role, everything is specified only down to the IP layer. The technology used below is up to the network operator. In many cases this will be Ethernet over copper (e.g. VDSL), fiber or Ethernet microwave.

Another example is the VDSL deployment of Deutsche Telekom (DT) in Germany. According to heise magazine 22/08, DT uses Ethernet over a Gigabit fibre (802.3ah) to their outdoor VDSL DSLAMs. Ethernet is also used over the last few meters of copper cable to the customer instead of ATM. While the VDSL modems can still do ATM, DT has decided to use Ethernet in combination with VLAN (Virtual LAN) encapsulation (802.1q). At the moment, only VLAN-ID 7 is used for all kinds of data, but there are rumors that DT plans to use several VLAN-IDs to separate IPTV from normal Internet access in the future with their IADs (Integrated Access Devices) that support Internet access, IPTV and (SIP) telephony.

IMS Service Discovery and Sharing

Recently, while in the dentist’s waiting room I had a bit of time to read another article from the always very interesting Ericsson Review Magazine. In the 2/2008 issue there are lots of articles on IMS. In the article on delivering the optimal end-user experience, the authors describe that their IMS application environment allows to share with other users which IMS applications one is using. This way, one can not only see if it is possible to use a specific application to communicate with someone but it’s also possible to see which applications others are using and thus to discover new services. Kind of a viral marketing approach.

I haven’t read about this in any IMS articles so far and it strikes me as a good idea, not only for the IMS domain. From the article, it’s not quite clear if this is something proprietary of the Ericsson IMS client environment or something that was standardized in 3GPP or OMA. If this is part of an IMS standard and you know where to find it, please leave a note in the comment section.

Book Review: Unified Communication Solutions

Unified Communications – The holy grail of combining information technology and telecommunication. There are lots of different opinions on what exactly UC is and when I was offered to have a look at a book giving an introduction, I couldn't resist.

Unified Communication Solutions – A Practical Business and Technology Approach by David Kim, Michael Gibbs and Bob Decker, published by Nortel press, approaches the topic in four steps. The first part of the book introduces the reader to how the evolution and integration of messaging, voice telephony and business applications forms a Unified Communication Solution. Business processes are streamlined with UC by making business applications interact directly with each other and by improving the interaction between people working on a common project and goal.

The second and third part of the book then show how UC can be used to enhance business processes such as Customer service, Customer relationship management, Supply chain management, enterprise resource planning and sales force automation. Quite a thorough analysis which not only discusses UC but also gives an overview of how companies are run.

UC is not a low hanging fruit, as lots of thought has to go into how to introduce UC applications into business processes and how to secure them. By tying information and communication together, new angles of attack for the bad guys emerge and the final chapter of the book gives an introduction of how to secure VoIP, SIP and UC solutions.

Personally, I've been using some of the UC elements described in this book for a couple of years now. Take my VoIP soft-phone and the IPsec VPN software on my PC for example. I can't remember when I last used a desktop phone as I find headphones and a proper address book for phone numbers navigated with the mouse much more convenient than anything a desktop phone could offer. This has opened totally new ways of working to me as I am no longer bound to a specific place but can do my work from pretty much anywhere where an Internet connection is available. Over an encrypted IPsec tunnel my e-mail, SIP telephony and corporate IM work just as well as at my desk in the office, which I rarely use these days.

Thanks to 3.5G networks now common pretty much everywhere I go, I don't even have to worry much anymore about how to connect. The first question of many callers these days is 'Hey Martin, where are you today', because they know I travel a lot or work from home and simply can't tell the difference from the connection or the caller ID of whether I am in the office or somewhere else. That's UC in action.

What I am still missing in my personal setup is the proper integration of voice telephony in my business applications, i.e. in Microsoft Office and Outlook. But then, what would the world be without some room for improvement?

While the book talks about mobile devices in some places, it's clear that this is not really the authors domain and I think this part of UC was treated a little bit too lightly in the book. (Yes, I know, I work in the mobile domain, so that comment had to come…). Another area that I wished were a bit more discussed is Web based tools for integrating communication functions into programs and web applications for communication inside the company and with the customers.

All in all, a great book and I managed to read it in about a week. In total, the book has 17 chapters and each can be read in 30 – 60 minutes. That's just the right time that can be set aside every now and then before other matters require attention or that train you are sitting in arrives at where you want to get off.