WirelessMoves

Top-12 Wireless Broadband Challenges

Here's a link to an interesting post that has recently been published on Wireless Week by Manish Sing of Continuous Computing on the top challenges LTE faces in the years to come. In the post he goes into the details of the different topics and it's a great read! Here's an overview of the topics he sees that will have to be sorted out as we go forward:

• Spectrum harmonization
• Voice over LTE
• Cell sizes, from femto to macro
• Backhaul
• Self Organizing Networks
• Security
• Devices and Terminals
• Traffic Management
• Flat Rate plans
• Intellectual property rights
• Interoperability
• Running several networks simultaneously

One thing I would like to point out is that these topics are not LTE specific. Whether an operator first goes down the HSPA+ path and only then starts thinking about LTE or goes straight to LTE, the questions and the issues are the same, just the answers might be a bit different. In other words, whatever mobile operators decide to do, the basic challenges are the same, with our without LTE.

The Vote is In: Old vs. New Media

National elections took place in Germany this weekend and if I had been at home and if I had a TV, I would have watched TV at 6 p.m. to see how things had gone. But I wasn't so I used my mobile phone to get the results. From previous experience I knew that the major news web sites could become quite overloaded at 6 p.m. so I used the built in FM receiver to listen to the six o'clock news for instant information. At the same time I also went to my favorite news web sites to see what they were saying. Here's the result:

My favorite one, Spiegel.de, was overloaded at 6 p.m. only a nice little error message was presented. Number two, Die Welt, did not have the results at 6 p.m., too slow guys, sorry. But finally, number 3, tagesschau.de, was both not overloaded (though a bit slow) and had the results I was looking for. I'd say that's still a clear tie between old and new media and shows that over-the-air broadcasting is still not out of date. For some things, the web is definitely not yet good enough.

Hm, maybe I should have tried Twitter, too!? Next time then.

Throtteling at the Base Station

Most "all you can eat" wireless Internet access offer these days do come with a traffic limit per month after which the connection is either cut, the speed is decreased or further charges apply. The aim of these measures is to ensure that a few users do not disproportionally use the network. Especially in wireless networks, where air interface capacity is the limiting factor, network operators try to bring some fairness into the game. However, the throttling is not happening at the air interface but in the core network. For the sake of fairness, however, I wonder if that is the right place to do the throttling!?

Wouldn't it be better to to have a sort of a soft limit and control it via the base station traffic scheduler? Here, the scheduler could take into account how much data each user has already transmitted in the past hour or day and thus give the packets to or from this user a higher or lower priority. Doing this at the base station would have the advantage that while the cell is not loaded, even heavy users get the full bandwidth while under heavier load, users that only browse the web get a higher priority and are thus not significantly slowed down by streaming or downloading activities of other users.

The scheme doesn't work for moving users but I assume that most power users with a notebook use bandwidth hungry applications in a stationary mode. I am also aware that taking the user identity and past use into account at the base station scheduler is not standardized in 3GPP and I am not sure if the base station scheduler can keep track of a users identity over state changes (i.e. from Cell-DCH to Cell-FACH to Idle and back). Nevertheless, an interesting "Gedankenexperiment".

Oh yes, and by the way, this kind of soft-priorization is not new, it's done for satellite Internet connections already.

FON on Femtos

Here's an interesting press release from FON, the company behind the FON hotspots that help you share your Wi-Fi Internet connection at home in exchange for free access around the world when you encounter another FON hotspot. In their quest to increase the number of FON hotspots, they have in the past already partnered with DSL providers in France and the UK to include their software in their home gateways. Now, FON has made an additional partnership with 3G femtocell maker Ubiquysis.

With this deal, future femtocells from Ubiquisys can also include the FON software so a home gateway can be used to enhance 3G coverage, to provide private Wi-Fi connectivity at home or in an office and can broadcast a public Wi-Fi signal. I think this setup might also make a lot of sense in hotels, airports and shopping areas and other places with lots of people who could benefit from better 3G coverage or Wi-Fi.

Now FON and Ubiquysis probably have to find out how to sell the concept to a fixed line / wireless network operator. I imagine that the incentive to include the FON software for a mobile network operator is similar as for the fixed line / wireless operators in France and UK. I'd say it is likely that they are splitting the revenue.

An interesting proposition that rises and falls with the popularity of Femtos. A winning cooperation? What do you think?

3 Like Home Not Abandoned in Austria!

After 3 UK has re-introduced roaming charges this summer, it is refreshing to see that 3 Austria still sticks to the 3 Like Home program, i.e. there are no roaming charges for voice and data in other 3 networks. I recently tested this in Italy with an Austrian 3 SIM card for a week and except for a few PDP context activation failures (roaming link down for a couple of minutes every now and then?) things worked well and I was charged the same rate as in Austria. Well done, 3 Austria, it's really great not having to change SIM cards at every border!

HSPA+ No Substiture for LTE

A follow up to this earlier post on LTE and capacity: Every now and then I see a debate of whether it is better to upgrade from HSPA to HSPA+ or to go to LTE. From a capacity point of view I think it's not an "or" decision, it's rather an "and" decision.

I don't see a reason why operators using LTE as a capacity extension in the 2.6 GHz band should not also upgrade to HSPA+ (before, after or at the same time) to make the best out of of the 2.1 GHz spectrum as well and to support as many HSPA users as possible. True, not all mobile devices will be HSPA+ capable for quite some time, but HSPA+ is backwards compatible thus taking everyone forward.

Especially once current equipment is end of life and replaced by multi-technology and multi-band base stations, potentially with new MIMO antennas that can be used simultaneously in the 2.1 and 2.6 GHz band, it seems rather a natural thing to do to me.

As always, thoughts are welcome.

VOLGA Stage 3 Specification Published

If you've been following my blog for a while you've probably noticed my support for Voice over LTE via GAN, or VOLGA for short. In case not and you are interested here's a link to a short intro and here a link to a whitepaper which I've recently written on the subject. It looks like the VOLGA forum has not been idle over summer and has continued working on the final stage 3 specification that contains all the nitty gritty details on messages, information elements, etc. Now in September 2009, the final version has been published which means all documents are together now to implement VOLGA. For the details, see here. Well done, I am looking forward to seeing the first implementations!

UMTS 900 Would Be Great For The Highlands

A random thought today: UMTS 900, the 3G variant running in the 900 MHz band so far mostly used for GSM is already used in a couple of countries like Finland and France to get 3G coverage to rural areas. Mobile devices for this frequency like from Nokia are also on the market already. The big difficulty with UMTS 900 is to find enough space in the narrow 900 MHz band for the 5 MHz carriers. However, I guess that is mostly an issue in cities and not so much for sparsely populated areas, like for example the Scottish highlands, where only a few GSM carriers are in active use and base stations are spaced 7 km apart or even more.

I know, the UK has so far not allowed the use of 3G in the 900 MHz band due to open market questions, but from a user's point of view I think it would be a great thing. In the mid and long term, however, I think the 900 MHz band will be opened up for other technologies, as even in cities, 3G and also LTE have/will have the big disadvantage compared to GSM of a much inferior in-house coverage. Going from a voice centric to an IP centric wireless network architecture, it seems like a natural evolution of things.

LTE as an HSPA Capacity Extension

Thought of the day: I keep hearing that LTE is great because you can go beyond the capacity of HSPA(+). Well, from an air interface perspective (Bits/s/Hz), that's going to be tough to achieve as HSPA(+) is going in the same direction capacity wise given the same amount of spectrum as LTE.

BUT, and that's how I haven't thought about it yet, LTE can be used in the new 2.6 GHz band, something for which HSPA is not specified and current base stations and many antennas are also not designed for. So once you get to the limit of your HSPA capacitiy, i.e. once you have used all the assigned spectrum in the 2.1 GHz band, you can use LTE to increase capacity with an overlay 2.6 GHz deployment. Where a lot of capacity is needed, range, which is going to decrease with the higher frequency, is also not a big issue.

Maybe you are lucky as an operator at this point and your 2G/3G equipment at this location is end of life and needs to be replaced at the time you run out of capacity anyway. It might then be possible to replace the old base station with a multi-technology, multi-band base station. If you are even luckier you manage to get a backhaul fiber to the site as we are talking triple digit MBit/s that have to be transported.

And at the same time you give your customers an incentive to upgrade to LTE: Higher speeds for them as they don't have to share the network with the masses anymore. At least for a while.

No EDGE in the UK

One thing that surprises me a bit about the UK wireless market is that despite being one of the most competitive in Europe, non of the mobile network operators have Vodafone does not have deployed EDGE in their its GSM/GPRS network. Some might argue that there is no necessity for it as 3G is the playground for mobile broadband these days. Not so fast I say though.

Take bigger cities for example like London. Millions of people must be out and about with their Blackberries, most of them still on GPRS/EDGE and not on 3G. They would surely benefit from an EDGE upgrade. Also, it would significantly increase capacity of the GPRS network as data is transferred more efficiently over the air. But capacity wise it doesn't seem necessary, as I haven't heard complains about slow Blackberry e-mail delivery in London yet.

Personally, I also often lock down my N95 to GSM only as web browsing with Opera Mini is very bandwidth efficient, it increases battery lifetime significantly and minimizes times the mobile looses coverage, e.g. when entering buildings and while I'm traveling by train. I also noticed no slowdowns in GPRS in London, which means that the current Vodafone GSM network capacity seems to cope well with 2G data traffic.

The Scottish highlands are the other extreme. Except in a few cities, there's no 3G coverage, and GSM base stations are spaced wide apart. That makes it a difficult terrain for broadband Internet. Again, Opera Mini performed very well on the GPRS only network but I had really wished for some EDGE so web browsing would have been possible as well.

But for the moment, it seems its not to be had. I wonder if integrated GSM/UTMS/LTE base station with a common backhaul link might change this in the future?