MWC: Vodafone and Failing Batteries at the Fira

When I get on a new mobile network I usually give it a thorough check for my research and to discuss results with interested operators. Most already do application testing on their own such as how many videos are viewed without interruption or how fast web pages load, etc. However, some do overlook some other important parameters.

One of the first things I noticed in Vodafone’s 3G network here in Spain at the Mobile World Congress is that sometimes when I log into the network with my mobile phone and remain connected, the battery runs flat within only 2 hours. A bit of research revealed that the reason for this is that they are assigning public IP addresses for transparent Internet connections (via the APN airtelnet.es).

So you might wonder what the battery drain has to do with a public IP address assignment!? Well in theory, not much, but in practice, quite a lot. When getting assinged a public IP address, all IP packets to this address get routed to the mobile device no matter whether they are wanted or not. Since IP addresses are dynamically assigned the new holder of an IP address potentially gets the ‘leftover’ from a previous user and all the junk emitted from viruses and other malware on the Internet. While the mobile device doesn’t really care and discards those incoming packets, the radio link is constantly active instead of falling back to a power conserving state while no user data is exchanged.

In my case I noticed that in some cases when I attached to the network the air interface link was constantly kept up as every couple of seconds an unsolicited IP packet was received. Most operators use network address translation (NAT), which assings a private IP address to the mobile and thus fixes this issue.

A somewhat crude fix for this problem from the user side short of hooking up the mobile to a power source once an hour is to fall back on the 2G GPRS network. The unwanted IP packets still come in but the power consumption in 2G mode is significantly less as the air interface link is kept for a much shorter time than in 3G mode after the last IP packet has been received and also requires less power.

So Vodafone, while I appreciate a public IP address for my 3G notebook dongle I think it’s a particularly bad idea for battery driven devices and user statisfaction. Also from a network point of view this is far from ideal as it wastes significant ressources on the radio link that would better be used for real traffic.

PS: I’ve noticed that there is also an APN with private IP addresses but that seems to be only good for web surfing as all my other applications are blocked.

MWC: 160 Characters Is Too Long, Network Load and Pictures

Fira1
Sunday, 15th of February and I am in the midst of the Fira to get things up and running for the Mobile World Congress. Not only physically but also virtually.

This year we are using Twitter to organize ourselves and by following the #mwc tag its fun to see what others are doing and experiencing. I noticed that while for other purposes 160 characters per SMS or Twitter message is far to short, for the current purpose it's actually too long. 160 characters are too long, that's a thing to think about in itself. When skimming through the #mwc messages on the mobile or the PC, the 100+ character "long" messages are just too difficult to read and I mostly skip them.

It's also interesting to observe the network load at the Fira. While the fixed line Internet worked quite well this morning, throughput is now quite erratic now in the afternoon. Vodafone's public 3G network on the other hand is still doing quite well. Let's see how that changes tomorrow with several thousands of people here in addition.

In case you are interested in pictures of what's going on here, have a look at Andrew Grill's Flickr Stream.

MWC: Blogging and Staying Connected with Less is More

Like every year I will post live from the Mobile World Congress in Barcelona again and provide my own angle on the show off the beaten path. Last year, I had a Nokia N93 and a Nokia N800 Internet tablet with me for the job. This year I was thinking about replacing the N800 with my eeePC as the web browser of the N800 is just too slow, i.e. very painful to use. However, after some deliberation, I decided against it, it is just too heavy to carry around all day. The benefit from having a full web browser and spell checker is just not big enough. So I decided that less is more and I will exclusively use my Nokia N95 and my Bluetooth keyboard to keep me connected during the week. Let the show begin.

MWC – Connectivity in Barca – Sometimes Even Plan C Fails

I arrived in Barcelona yesterday for the Mobile World Congress which does not start until next Monday (or Sunday, depending whether you count the pre-congress parties or not…) but it's nice to be here a couple of days early to relax a bit. I am usually used to just replace my SIM card with a local one or at least with one that has acceptable roaming rates and get connected in a couple of minutes. What I experienced yesterday, however, reminds me of days that I thought were long gone.

After having arrived at the airport I replaced my French SIM with one from German MVNO "Medion – Alditalk" to check my e-mails on the mobile before I could top up my local SIM card or buy a new one after baggage claim. Unfortunately, while the SIM card booked into the circuit switched part of two networks o.k., I could not get a data connection on the packet switched side (GPRS attach fail). O.k. Medion – Alditalk is not really known for their stable network operation so I moved to plan B.

From last year I still have two local SIM cards from Yoigo. One was not working anymore, while the other still booked into the network (both CS and PS attach ok). No idea why one is still activated and the other is not!? Anyway, so I went to the next store at the airport to put some money on it again (the balance was at zero since they deduct 6 euros per month if not used). Unfortunately I had to find out that you have to know the phone number to top up. Eh, sorry, can't remember, I am used to scratch card top ups…

All right, time for plan C, by now already at the hotel. My German Vodafone SIM card with the Websession option gives me 50 MB of traffic for 15 euros / 24h while roaming. While it worked fine on the Vodafone Spain 2G network, my N95 refused to work on their 3G network (PS attach ok, PDP context activation ok, but only spurious ping replies). Network/mobile incompatibility? Hm, so I put the SIM card in my E220 3G USB dongle but the effect was still the same. So either the 3G cell near the hotel is having problems or there is a more serious problem up the line.

So plan D for the moment is to use the Vodafone SIM on the slow GPRS network for mobile use and the crappy hotel Wi-Fi for the notebook. In the meantime the Medion – Alditalk SIM is booking into the GPRS network of Orange again, so I could now also use that.

Well, I guess that was not really my connectivity day… Let's hope things work out better today. All this and the 50.000 people coming to the congress haven't even started yet to put load on the networks in Barcelona.

Dual Carrier HSDPA – The Push Beyond 5 MHz

Over at LinkedIn, Eiko Seidel recently published a link to a whitepaper by Nomor research on Dual Carrier HSDPA (or Dual Cell HSDPA operation as it is called in the standards), a new feature currently worked on in 3GPP. I've been waiting for this feature to come out for quite some time now as HSPA+ has already added 64QAM modulation and MIMO to HSPA. Consequently, not much can be done anymore to improve performance in a 5 MHz channel.

In practice, dual carrier (DC) HSDPA means that two adjacent 5 MHz carriers can be bundled by the network and DC capable HSPA mobiles can be assigned resources simultaneously on both carriers. In addition to the higher throughput, the 10 MHz bandwidth can also be used to schedule mobiles more efficiently around fading conditions, which according to the paper, results in an efficiency gain of up to 7% with 32 users and up to 25% with 2 users.

By increasing transmission speeds the round trip delay time is also further reduced, good news for online gamers. I have to note, however, that current round trip delay times of around 100ms are hardly distinguishable anymore from the delay of a DSL line. What's still distinguishable are the longer delay times caused by state changes after some time of inactivity. That's addressed by another feature, though, the enhanced Cell-FACH.

The enhancements also brings a number of new terminal categories. In addition to HSDPA terminal categories 1-20 which exist today (most people these days have a category 6 (3.6 MBit/s) or a category 7/8 (7.2 MBit/s) device), category 21-24 terminals will be able to use two adjacent carriers. The conserve energy on the mobile device side, the network can dynamically instruct such terminals to only listen to a single carrier if the amount of data to be transferred is low and doesn't warrant the use of two simultaneous carriers which requires more energy for decoding.

For the moment, multicarrier HSDPA is only for the downlink direction and while 64QAM is included, MIMO is not. Theoretical peak throughput in the combined 10 MHz carrier is around 42 MBit/s. But I guess this is not the end of the story yet, I think it is quite likely that in 3GPP Release 9, uplink dual carrier and MIMO is added to the feature list. The authors go a step further and speculate that in the future the standard could include further enhancements to go beyond two simultaneous carriers and to even include simultaneous transmission on carriers not adjacent to each other, even in different bands (e.g. 900 + 2100 MHz simultaneously).

While it looks good on paper, it remains to be seen which operators will go for it in practice. Some operators are determined to squeeze out as much as possible of their 3G networks before going to LTE. By the time these features are market ready, I'd say two to three years down the line, it's quite likely that many 3G base stations will already be used with two carriers per sector. If the feature can be done in software only, I guess it could become quite popular. In that time frame, however, many of today's 3G base stations will be end of live and might be replaced with triple mode GSM, UMTS and LTE base stations. If the feature is required when LTE is also in the cabinet, well, that remains to be seen.

But one way or the other, this new round of enhancements show that there is still a lot of life left in HSPA.

And here's some background as to where the technical details can be found in the specifications: First, 3GPP TR 25.825 contains an overview of the feature. Nomor's whitepaper lists a number of Change Requests (CR) to add the functionality to the relevant specification documents (TS 25.211, 25.212 and 25.214). I've had a look at the latest versions in 3GPP Release 8 and those CRs have been approved and are part of the specs now. So it looks like Dual Carrier HSDPA will be part of Release 8 which will be finalized in this quarter.

Let's see if there is already talk about this at the MWC in Barcelona in just a couple of days from now.

Moving From Being Networked to Being Connected

In his book "Mobile as the 7th of the Mass Media" Tomi Ahonen has an interesting description of how the cellphone (I would call it 'the mobile device') changes the way people use the Internet: It moves the experience from 'being networked' to 'being connected'. It totally applies to me.

When I think back to the early days of the Internet, I was indeed networked: I specifically sat down in front of a computer to access the Internet, i.e. to get to my e-mails and to search for information. Once I got up and left the place, I was disconnected. Yes, I was networked, but not all the time.

Today, I don't go to a specific place anymore to access the network. Today, I have a mobile device and it is always connected to the Internet. I no longer open an Internet session and close it, it's just there all the time. I don't log on to check for my e-mails, an indication is already waiting on the idle screen when I look at it. When I search for something, I don't log onto the Internet and start the browser. The phone is already connected to the Internet and the browser is waiting in the background to be used again. And for that matter, so is my social network, the news and all those web 2.0 applications that allow me to see things created by my friends at the other end of the planet just seconds ago and let me put my pictures and content online as well for them to see. And all without sitting down and logging in. For me, the 'net' has become omnipresent, I am logged on 24h a day.

I haven't mentioned voice telephony so far specifically but that's because for me it's just an application running over the Internet as well these days. While I still use the circuit switched cellular network a great deal for voice calls, I most mintues are via Voice over IP now. Thanks Nokia for the great SIP implementation in the N95, it saves me a ton of money for those international calls.

But beware, being connected 24h a day does not mean that I am reachable for everyone 24h a day as well. It's a big mistake people make on both sides of the equation. Some think that once your are always connected you must be reachable. Others think you are forced into it and are thus trying to avoid it. I don't think so and I don't live it that way. With profiles that can be changed with the press of a button I decide who can reach me and who can't.

So I guess here's the difference for me between today and the past: In the past I had to decide when to connect. Today, I have to decide who can reach me at what time. I rather prefer it that way.

Breaking HTTPS Connections in Two Parts Considered Harmful

Last week, About Mobility and Masabists ran a story on the difficulties mobile transcoders have with secure HTTP connections and how they can put themselves into the the connection and thereby breaking end to end security. I've done some research on my own and since I am quite opinionated on the topic I wanted to post my results and thoughts here as well.

O.k. so first of all, what is the fuzz all about in simple words: Today, when somebody uses his mobile browser to connect to his bank, a secure HTTP (HTTPS) web connection is established to the mobile portal of his bank. HTTPS means that before any data is exchanged the banking portal sends a certificate the browser can cross check to ensure that the browser really talks to the server of the bank and has not been redirected to another site. After the certificate has been received, an encrypted end to end connection is established that no one, not even a mobile transcoder in the network can put itself into.

So for the user this is good since he can trust HTTPS to verify that he is really connected to the bank and he can also trust that all data that is sent and received is encrypted from end to end. For the transcoder this is bad since it has no chance to transcode the content and do other things with it.

So some smart people came up with what is called link rewriting to circumvent this 'issue', if you want to call it that way. With link rewriting, the transcoder doesn't forward a web page to the user with an original HTTPS link but with an HTTPS that points to the transcoder itself. When this HTTPS connection is established a secure connection is only established to the transcoder itself. The transcoder then establishes a second HTTPS link to the original server.

This means that the user no longer has a end to end encrypted protection but has to trust that the transcoder keeps his data secret. Also, the user can no longer verify if the transcoder contacts the original server, as the certificate that can be queried in the browser is that of the transcoder and not that of the original site.

In addition, this is totally transparent to the user as he will still see the "lock" icon that suggests an end to end secure and encrypted connection. Only when the user actively looks at the certificate will he actually see that the connection is terminated at the transcoder.

Counter measures: The only way for the user to ensure that this does not happen is to save the original https link as a bookmark. This way the transcoder has no possibility to rewrite the URL and hence can not put itself in the transmission chain.

From a user point of view I consider breaking a HTTPS connection in two parts as very harmful. It only takes one incident where data is stolen via a leak in the transcoder to damage HTTPS' reputation. Also, if it is suddenly acceptable to break HTTPS connections in two parts for reformatting purposes, why not also use it for statistics or to ensure no content the provider does not approve of traverses the network!? No way, the data inside an HTTPS connection only belongs to the user and the server at the end and to no one in between, no matter how good the intentions of the party in the middle are.

My Latest Book is Now Also Available at Amazon in the US

I've noticed today that after the launch of my new book last month in Europe, it is now also available on Amazon in the US. It took a bit for the bulk shipment from the UK to arrive but now that it's available, sales seem to have picked up quite quickly. At the moment, Amazon.com says only a few copies are left and more are on the way. Thanks to all who have already ordered a copy! So if you live in the US or Canada and have considered getting a copy from Amazon.com, now's the time. At some point it will go back to "shipping in 7-10 days" status but it's usually restocked much quicker now that it is available from a local distribution center.

Opera Mini for Android

As an avid user of Opera Mini I was very happy to see that the version v4.2 is now available for Android. Alphas and betas have been available since last October/November so announcing a non beta version probably means it's quite stable by now. Good news for G-Phone users and mobile Internet access in general. Kudos to Opera, looking forward to see it on the G-Phone in Barcelona at the MWC!

Vodafone Germany Now Earns More With Data Than With SMS

Interesting trend to observe these days in Europe: The revenue generated from data services in mobile networks is now close or even surpasses the revenue generated by SMS services. Recently, Vodafone Germany reported their numbers of the previous quarter compared to the quarter a year ago here and the table shows how data service revenue is now slightly higher than SMS revenue. Only a year ago, data revenues were still significantly behind.

What the table does not show, however, is that from an earnings point of view, SMS is probably still far ahead. After all, transferring 160 character messages through the network at a price of around 10 cents makes a far better bottom line than the megabytes of data transferred at a flat rate. But nevertheless, things are changing and it shows how mobile Internet access continues to increase in importance to mobile network operators.