WirelessMoves

When I was recently on vacation I visited friends and incidentally they all lived just outside of smaller towns on the countryside. They all had a DSL line at home but mobile network coverage was weak at best. Apart from being a nuisance for me they said themselves that they were not happy with the mobile network coverage in their house. And it was not like they were living in totally remote areas. Perfect places for femto cells!

So while femtos haven't really made a big inroad in most countries over the years so far, I still see the potential and the need, especially since people more and more use their mobile phones instead of fixed line devices for voice calls. Sure, Wi-Fi and SIP clients could also do the trick on their devices when they are at home but it's not seamless and doesn't work for their guests. Fortunately, Vodafone seems to expand their femto solution to more countries beyond the UK now so let's see, perhaps that might be a solution for such locations and perhaps a reason for the competition to wake up.

In  recent comment to a blog post, Sergey observed that the usage of the terms 3G and 4G is completely different in the US and Europe. While in the US, the term 4G is used instead of LTE, it's exactly the opposite in Europe, where the term 4G is not very prevalent and LTE is used in the mainstream press. Both parts of the world have reasons from a marketing point of view to do one thing or the other. And by the way, some even call UMTS networks 4G in the US. And to dazzle you even more, a well configured dual carrier UMTS network can easily compare with a 10 MHz LTE network, the prevalent bandwidth in the US, or even surpass. And to drive the point home, a 20 MHz LTE network in Europe easily beats a 10 MHz network in the US. There we go, the terms 3G, 4G are completely meaningless but unfortunately suggest that one thing is better than the other when even 4G can't be compared to another 4G network.

So perhaps we have to go back to the roots? Perhaps everything based on UMTS should be called UMTS and everything based on LTE should be called LTE, at least by engineers who know what they are talking about!? And if you really want to compare performance, the terms won't help much just like the terms 3G and 4G. But at least they don't have this bias in them intrinsically that suggests one is better than the other. Well, and if one really discusses performance, then one has to to pull out lots of parameters such as bandwidth used, modulation and coding schemes available, cell site density, backhaul capacity, etc., etc., irrespective of the technology used.

Recently, Techcrunch and Gigaom reported a couple of very interesting technical details on the amount of data and number crunching over at Facebook. Here are some:

• Current amount of data stored: 100 petabytes. That is 100.000 terabytes! Imagine the physical amount of space required to store such an amount of data…

• 500 terabytes (i.e. 0.5 petabytes) of data added each day, including 300 million new pictures.

• 105 terabytes of data analyzed every 30 minutes.

Anyone's got a link to original material on this, I'd like to hear/see it from them first hand!?

If 0.5 petabytes are added per day that's 182.5 petabytes per year if user behavior stays the same even without adding new users. Makes one wonder how long they can keep up with the amount of data they have to store as cost for it will rise as well. I wonder if the storage and power costs per TB of data is decreasing as fast their data store is increasing. Kind of a life and death question if you don't want to throw away data at some point unless you can increase your revenue at the same time with storing more and more data.

 

Many years ago when I first ventured into mobile I got myself a SIM card reader with a serial interface because I found a neat program called "SimSpy" that could read lots of fields on the SIM card and interpret their contents. Time has moved on, serial interfaces on computers became a thing of the past and my serial SIM card reader would not work any longer without a USB adapter. In other words, I pretty much forgot about it. But recently, I had the need for a SIM card reader again so I bought a new one straight with a USB interface for 16 Euros as the description mentioned that it supported a number of, let's say, 'traditional' API standards. For details see the (German) description on Amazon. And indeed, the included driver installed flawlessly even in a virtual machine running Windows XP and the latest version of SimSpy had no problems finding the card reader and reading the SIM cards I inserted (see picture on the left, with a couple of sensitive fields blanked out…). Very neat indeed!

They
are installed on pretty much on every bridge over major roads these days: Traffic
jam sensors. Recently, I got to see one close up and found it quite
interesting that they are totally autonomous, no network cable (of
course) but also no power cable. Have a look at the picture on the left.
According to the website of the company that has deployed those
sensors, data is sent over the GSM network when necessary, i.e. only
when the traffic flow changes. No mention whether SMS or GPRS is used
for the data exchange.

Then I wondered how much power the sensor
draws and if the solar panel could supply enough power for a round the
clock operation? The module has a size of about a quarter of a square
meter so how much power could it deliver per day? From experience with a
solar panel that had a size of about 4 square meters that could deliver about 500 watts under best conditions this module could perhaps deliver around 30 watts under the best conditions. Now the sun is not always shining so perhaps the module delivers 100 Wh per day. Is that enough?

That depends on how much power the device draws. The radio module itself is probably pretty efficient. Idle mode power consumption of embedded modules is typically less than 10 mW. So letting it run around the clock would result in a power consumption of the radio module of around 0.24 Wh per day plus the increased power consumption for communication. I assume the device only communicates rarely so this value should not increase much. And then there's the application processor board and the sensors themselves. As their main job is to count and analyze impulses it gets when cars move under the sensor I can imagine that its power consumption is equally low. But even if it takes a full watt, the solar panel and a battery to store energy for nighttime should be way sufficient to drive the device. And a full watt is already quite a lot, even a Raspberry Pi Model A under full load is specified to take only 1.5 Watts.

With all that is going on at the moment in the UK with the Orange/T-Mobile merger, LTE in 1800 MHz, upcoming auctions for 800 and 2600 MHz spectrum in 2012, potential sale of 1800 MHz spectrum of EE to H3G, etc. it's a bit difficult to keep track of who actually has spectrum where and how much. Is your head spinning? Mine does.

But here's an interesting document released by Ofcom that shows who has what kind of spectrum in 2012 that sheds some light on the current situation. The details are on page 8. Quite insightful.

It looks like even though SMS messages can't be sent free of charge, SMS spam and fraud seem to be on the increase and I suspect a significant part of the population may be vulnerable to be tricked into calling premium numbers that way.

When I recently talked to a somewhat elderly person I was told a story about an SMS the person had received which looked like it was sent by a popular parcel service company. The message said that they had tried to deliver a parcel but found nobody at home to receive it. The message then requested the person to dial the number in the SMS message (or click on it) to call the parcel service to arrange for another delivery. The number, of course was a premium number but not all people recognize such numbers, especially in countries that don't use 0900 or other well known codes for such numbers.

In this particular case, no damage was done because when the person tried to call the number it was already deactivated. It looks like the fraud was discovered and shut down.

What is really bad about the whole thing is that even after I explained that the SMS message was a scam to trick people into calling premium numbers, the person still insisted that the message has come from the parcel delivery service. I am not sure my explanation has sunk in 🙁 And the person I was talking to was not dumb, just not born in the mobile age…

When watching the Sol 4 press conference for the Mars Science Laboratory (MSL) mission, better known for the Curiosity rover, the person responsible for the on-board computers was saying that the on-board computer was less powerful than an iPhone. One reporter in the audience was totally baffled by this and asked how it was possible to fly to Mars with something that had less power than the smartphone in his pocket.

A very revealing question as it shows that the general public has no idea of how much processing power is required if no screen is attached to a device and software is highly optimized for a specific purpose. It would probably be even more incomprehensible to him that when flying to the moon, the Apollo Guidance Computer did not run at 1 GHz like his iPhone, but at a mere 2 MHz (500 times slower clock speed), and instead of Gbytes of RAM and flash it contained the equivalent of a meager 4 kbytes of RAM and 64 kbytes of ROM. For the details see here and for the details on the bit level have a look at this excellent book which I just recently finished reading. In other words, the specs are similar to those of a 1980's Commodore 64, even though it's difficult to compare those two computers due to their very different purposes.

But anyway, this made me wonder how many times you could store a C64 game that filled the better part of a 5.25" disc or tape in the days of the C64 on an iPhone with 16 GB of flash today. Let's take the original Giana Sisters game on the C64 for the calculation. The disk image has a size of 174 kbytes to play it in a C64 simulator today. And that's already quite big as the C64 only had 64k of RAM so perhaps it was compressed in some form or shape in memory. But anyway, 174 kbytes it is, more than the ROM of the Apollo Guidance computer could have held only a decade and a half earlier. For the comparison let's take an iPhone with 16 GB of flash, which is roughly 16 000 MB or roughly 16 000 000 kb. The game would fit into the flash memory 91 954 times!

Stunning!

An annoyance when working on the settings of a network is that the PC used for the task becomes part of that network and depending on the job, looses Internet connectivity. Even if a 3G stick or second network adapter is used, DHCP settings, which are part of the setup mingle with the PCs settings and again cut the Internet connection. A hassle I have now found a remedy for: Wi-Fi in a Virtual Machine.

A few weeks ago I had a post on how to do 3G testing in a virtual machine but this did not extend to working in wired or Wi-Fi network. But by simply getting a USB Wi-Fi stick and making it available to the guest operating system running in the virtual machine, working on a network is completely isolated from the host computer. The picture on the left shows how this looks in practice. The host operating system uses the built in Wi-Fi chip while the guest operating system (Windows XP in the window) uses a USB Wi-Fi stick and connects to the network to be configured. No matter what is done there and how that affects the client operating system, the host operating system (Ubuntu in my case) is entirely unaffected from the changes as it uses a different network and Internet connectivity remains in place.

And if you have enough RAM you can even launch two or three virtual machines simultaneously, each using a different Wi-Fi or 3G dongle connecting to different networks. Great for testing VPN solutions, NATing, etc. etc. The more I play with Virtual machines, the more uses I find for them.

Now here's the perfect gift for a telecoms man who doesn't really have all that many wishes for someone to fulfill easily. Every now and then when tracing signaling messages, being able to spot or decipher numbers in binary is essential. But when not doing it regularly, the process is a  bit cumbersome. But here's the solution: Train you binary skills with a watch that displays the time of day in binary. After two days I was fluent again 🙂 Priceless…