Author: Martin

Just before Christmas 2011, the French regulator ARCEP announced the result of the auction of the 2×30 MHz spectrum in the 800 MHz digital dividend band. All three incumbents, Orange, SFR and Bouygues each won 2×10 MHz. Free has been unsuccessful to get spectrum directly but SFR is mandated by the spectrum auction terms and conditions to cooperate with Free, (probably) because they have won the 10 MHz that are in the middle of the frequency range.

Unfortunately, the press release does not quite reveal why it is SFR that is specifically required to share their spectrum with Free!? Also, the the 1 billion SFR paid for the middle section is 320 million more than what Bouygues had to pay for the lower section and still another 120 million higher than what Orange had to pay for the high part of the spectrum. Each of them still have 10 MHz. So I am not quite sure why the middle part is the most valuable part of the band. I could imagine that the lower part might imply some more coordination efforts with terrestrial TV transmissions which use the frequency range just below. But the higher part is unaffected by this so why is SFR required to share the network with Free and not Orange? The press release doesn't go into those details so if you know, please leave a comment, I'd be quite interested in this.

Other interesting bits and pieces mentioned in the press release:

• All three network operators have committed to allow "full" Mobile Virtual Network Operators (MVNOs) in their network. It's not quite clear to me how "full" MVNOs are defined but let's hope it will encourage more competition and thus better prices and conditions for customers in the future compared to the very closed and non-competitive French wireless market compared to other countries in Europe today.

• There are similar requirements as in Germany to ensure the 800 MHz spectrum is first used in rural areas to bring Internet connectivity to under-served areas. From the press release: "[the network operators] must commit to an accelerated rollout schedule in the most sparsely populated parts of the country".

One of the things I have observed in the past when offering Internet access at meetings is that ISPs return IP addresses of DNS servers which are only slowly or unreliably answer DNS requests. This is why by default I don't go to these anymore but use Google's own DNS servers reachable via the easily memorizable IP address 8.8.8.8. This IP address is reachable in all parts of the world I've been so far with only minimal latency.

Recently, however, when I was on the Philippines, I noticed that while the Google DNS server responded to ping requests, there were no answers to DNS requests. As the issue continued over a number of days it seems that either the outgoing DNS requests were blocked or incoming DNS responses were discarded before reaching me. I did a search on the web to see if there is any information whether the Philippines block foreign DNS servers but came up empty handed. If you know more, please let me know, that would be quite interesting.

I've been on the Philippines recently for a round of meetings and it was interesting to observe the availability of bandwidth for non-secure and VPN encrypted traffic to oversea destinations.

During the later parts of the evening, at night and during the morning, I could easily transfer 2-3 MBit/s a second over my VPN connection. If I dropped the VPN connection and went to the same overseas websites directly and downloaded email (still encrypted over secure POP3 and secure SMTP), speeds were in the same region. During the day however, speeds over the VPN connection dropped to 200 to 300 kbit/s while unencrypted access to web resources in Europe and the US remained above the 1 MBit/s level. The difference remained even when I changed the VPN transport type from UDP packets to TCP packets terminating at the https port 443.

The same effect could be seen no matter whether I used the hotel Wi-Fi or the 3G network via a local SIM card. That likely means that it's the overseas link that becomes congested during the day. Just strange that encrypted connections were more affected by it than plain http traffic. Also, it didn't matter whether the VPN tunnel ended in the United States or in Europe, throughput levels were equally low during business hours.

I wonder if all that means there is a special preference for certain types of traffic for oversea links!? It was also interesting to observe that my company VPN, which works with a different technology than my private VPN based on OpenVPN was throttled down even further during the day time to 100 kbit/s and sometimes even less. Other participants at the meeting noticed the same behavior which is a bit of an annoyance if everyone depends on new versions of documents stored on a server abroad.

To overcome this limitation I mirrored some documents for the meeting on a local server on the IP subnet the Wi-Fi access point supplied. Unfortunately, not all participants could access local resources as many company firewalls and VPNs prevent devices to access local resources.

An interesting reverse strategy happening at the moment on my smartphone:

Instead of having Wi-Fi activated on my smartphone by default to benefit from cheap internet access at home and access to local resources I am rather opting now to have it switched-off by default unless I really need it, e.g. to download podcasts, videos etc.

Why? Because my current smartphone's Wi-Fi reception is quite restricted and I've experienced a couple of times that while it could still see the Wi-Fi access point it had difficulties to transfer data due to the reception level. Instead of switching to the cellular network, however, it got stuck. Not good, this is not yet implemented well. Also, I usually don't use any local resources such as a NAS server with my smartphone and I also don't use it as a remote control for any gadgets residing in the home network. I travel too much so my home network is rather basic compared to others.

When comparing the reception quality of smartphone with larger devices such as notebooks it seems that it is in general much weaker. While my notebook sized devices still receive the Wi-Fi network very well in remote corners in my apartment, mobile devices already have difficulties. So unless that changes and I have an all-you-can-eat 3G data package anyway and don't hit the throttling limit, my smartphone Wi-Fi will stay off at home.

What about you, do you use Wi-Fi at home and what are your experiences concerning reception and range?

Nokia's recently produced a couple of Dual-SIM phones which I haven't seen around much in Europe. When visiting the Philippines, however, I could observe them being marketed by the local Nokia stores alongside pretty much anything else in the Nokia portfolio, including the Nokia N9 and, as a major absentee, the Nokia Lumia.

While observing the people in a park in Makati, Manila's business district, I noticed that quite a number of people had at least two phones with them, some of them even three. When asking why, I was told that most people use on-net "all you can eat" packages while voice calls and SMS messages are rather expensive. So it seems to be cheaper to get a couple of prepaid SIMs from different networks and extra phones rather than to pay for inter-operator charges. So for people with a quite restrictive budget, a Nokia Dual-SIM phone probably makes a lot of sense.

People in the Makati district, however, probably have a significantly higher income than the average consumer in the country and I could observe that one of the two phones was usually a smartphone while the other was a what many people a low end phone. The smartphone was usually either an iPhone or a high end Samsung or HTC Android based device. I failed to see anyone using a Nokia smartphone.

… asks David Talbot in a recent article on the Technology Review website. An interesting question and I'd really like to see a solution that shows who receives what kind of information from apps or the operating system itself that is originally shipped with the device.

But not through a cloud of fine print as is often the case today but detailed and to the point please. With a number of discoveries over the past few months of location information and private data being harvested and sent off mobile devices lately without users being aware of the fact, I think it is really time for this. Also I think it would be a good idea to put some law behind this to ensure that there are consequences if the devices does more than actually described in such a list.

Obviously such a feature would have a difficult time to track what kind of data third party applications send out but I think the point of such a feature would be to ensure that the user knows what he gets at the time he buys the device. Anything installed from a third party later on is his own responsibility. And Android, for example, makes it quite clear what kind of capabilities an app requests during installation and it doesn't take much imagination what an app can do when it requests Internet connectivity and access to calendar and address book.

3GPP standardization is well ahead of real life deployments and it has to be, as developing and testing the ever more complicated features takes time. Currently, Release 8 of the specifications has made it into the real world, with HSPA+ Dual Carrier deployments and first LTE networks now in commercial use. So from a radio access, speed and capacity point of view, what's in store between this and what will Release 11, that is currently under development, put on top of it?

A detailed resource listing the new features of each Release can be found here. If you have a look you'll immediately see that my list below is but a tiny fraction of what has been done in each release. My focus for this post, however, is very narrow and only looks at how the capacity of the macro base stations is enhanced as we go forward.

In Release 9, HSDPA gets enhanced by adding MIMO to Release 8's combination of Dual Carrier + 64-QAM, pushing theoretical peek data rates from 42.2 MBit/s to 84.4 MBit/s. To make things more flexible, the two 5 MHz carriers can now be in different frequency bands. In the uplink direction, dual carrier operation is introduced (while having been present in the downlink since Release 8), thus pushing theoretical uplink data rates beyond 20 MBit/s.

With Release 10, 3 and 4-carrier HSDPA is specified in up to two different frequency bands. Like the already existing dual-carrier feature, aggregating carriers has little impact on overall capacity of the network but offers higher peak data rates to individual users. On the LTE side, carrier aggregation beyond the initial 20 MHz is introduced and the number of antennas for MIMO in the downlink direction is increased from 4 to 8. Again, this is well beyond what is used in life networks today with up to two independent streams in the case of LTE. In the uplink direction, up to 4 antennas are now specified to increase data rates under ideal conditions.

From a raw maximum throughput point of view it seems that a limit has been reached. It is unlikely anything more than 64-QAM modulation makes sense and 8 MIMO data streams will keep engineers busy for a long time to figure out how to put such a high number of antennas on roof tops and crammed into small devices.

But ultra high data rates are not everything when it comes to overall maco network capacity. A major issue is interference between cells, especially for users that are at a location where they get a strong signal from more than one cell. Here, higher order modulation and MIMO is not much help.

Therefore, one of the major topics in 3GPP Release 11 in this respect is Coordinated Multi-Point (CoMP) transmission. Nomor's current LTE newsletter shows this quite clearly by giving an overview of currently active work items in the different RAN working groups.

Here's an abbreviated list of the objectives of CoMP from the current version of the work item description (RP-111117):

• Specify the support of intra- and inter-cell CoMP
• Joint transmission
• Coordinated scheduling/beamforming

And, in case that has sparked your interest, further details can be found in the study item 3GPP TR 36.819 that preceded the current work item.

Coming back to the title of the post "the air is getting thin", it's interesting to observe that after years of specifying how to get ever faster data rates, significant work is now done around improving data rates in places far away from a good signal. Not only will this help individual users to get a higher data rate in such places, but network capacity in general is increased by spending less time transmitting and repeating lost data slowly with a very low modulation and coding scheme. It will take a few years before we see this in practice but I think chances are high that the result of this work item will see the light of day.

I've been to a hotel recently that was just newly built and which had the latest window technology for heat insulation. That's all nice and well but for mobile networks on the outside, such windows are almost impenetrable.

The path loss through these windows were 30 db, so even a base station pointing directly at the hotel having a great 3G signal outside the hotel (-60 dbm) dropped to still acceptable (-90 dbm) just inside the hotel to a complete "nothing" just a few meters inside. Without dedicated in-house coverage via leaky cables, femtos, repeaters, etc., hotel guests are having a hard time if they want to use the networks outside.

Interestingly enough, standing close to a window helps but standing to a wall is actually much much better, the path loss in my case was only 10 db instead of 30. Quite a counter intuitive thing to do.

Having your Skype client open on your PC also means that your network can be used for relaying other Skype calls if the system detects incoming TCP/UDP connections can go through your NAT firewall (e.g. due to UPnP opening a few ports). It seems this doesn't happen very often as I haven't observed a relay session over my PC until recently, when I suddenly had a 200 kbit/s data stream in both direction running over my PC for several minutes.

Wireshark is always close at hand so I could quickly confirm that the data stream was indeed to and from the Skype client. A Reverse DNS lookup then revealed that the call was between two other PCs in Germany in networks of different providers. That probably means that the DSL routers in those networks do not have UPnP enabled, otherwise the IP packets could have been exchanged directly between the two parties. Also interesting to note was that the relaying went over my Wi-Fi. So unknowingly to those on the call their data packets went over a wireless link at least twice, probably even four times if you assume that both parties used Wi-Fi at their end as well.

ARCEP, the French regulator has reportedly given the go ahead to Iliad, also known as "Free" to officially launch their 3G network as they have fulfilled the initial minimum coverage condition as they now cover 27% of the French population with their own network. A national roaming agreement with France Telecom / Orange will do the rest for now. The Free network launch is the first in many years in Europe and it's actually the exception from the current norm of networks being combined in other countries to reduce competition. It's going to be interesting to see how well Free will be doing and what kind of effect it will have on competition and pricing in France. I wish them all the best, perhaps I can become a customer soon if they offer interesting prepaid packages!