November 2010

Design and Mobile computing and Networking & telecommunications and Systems and Technology19 Nov 2010 at 16:32 by Jean-Marc Liotier

In France, at least two mobile networks operators out of three (I won’t tell you which ones) have relied on Cell ID alone to identify cells… A mistake because contrary to what the “Cell ID” moniker suggests, it can’t identify a cell on its own.

A cell is only fully identified by combining with the Location Area Identity (LAI). The LAI is an aggregation of Mobile Country Code (MCC), Mobile Network Code (MNC – which identifies the PLMN in that country) and the Location Area Code (LAC – which identifies Location Area within the PLMN). The whole aggregate is called Cell Global Identification (CGI) – a rarely encountered term, but this GNU Radio GSM architecture document mentions it with details.

Since operators run their networks in their own context, they can consider that MCC and MNC are superfluous. And since the GSM and 3G specifications defines the Cell ID as a 16 bit identifier, the operators have believed that they had plenty for all the cells they could imagine, even taking multiple sectors into account – but that was many years ago. Even nowadays there are not that many cells in a French GSM network, but the growth in the number of bearer channels was not foreseen and each of them requires a different CellID – which multiplies the number of cells by their number.

So allĀ  those who in the beginnings of GSM and in the prehistory of 3GPP decided that 65536 identifiers ought to be enough for everyone are now fixing their information systems in a hurry as they run out of available identifiers – not something anyone likes to do on a large critical production infrastructure.

Manufacturers and operators are together responsible for that, but alas this is just one occurrence of common shortsightedness in information systems design. Choosing unique identifiers is a basic modeling task that happens early in the life of a design – but it is a critical one. Here is what Wikipedia says about unique identifiers :

“With reference to a given (possibly implicit) set of objects, a unique identifier (UID) is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose.”

The “specific purpose” clause could be interpreted as exonerating the culprits from responsibility : given their knowledge at the time, the use of Cell ID alone was reasonable for their specific purpose. But they sinned by not making the unique identifier as unique as it possibly could. And even worst, they sinned by not following the full extent of the specification.

But I won’t be the one casting the first stone – hindsight is 20/20 and I doubt that any of us would have done better.

But still… Remember kids : make unique identifiers as unique as possible and follow the specifications !

Brain dump and Debian and Free software and Systems administration and Unix17 Nov 2010 at 19:54 by Jean-Marc Liotier

On I stumbled upon this dent by @fabsh quoting @nybill : “Linux was always by us, for us. Ubuntu is turning it into by THEM, for us“.

It definitely relates to my current feelings.

When I set up an Ubuntu host, I can’t help feeling like I’m installing some piece of proprietary software. Or course that is not the case : Ubuntu is (mostly) free software and as controversial as Canonical‘s ambitions, inclusion of non-free software or commercial services may be, no one can deny its significant contributions to the advancement of free software – making it palatable to the desktop mass market not being the least… I’m thankful for all the free software converts that saw the light thanks to Ubuntu. But nevertheless, in spite of all the Ubuntu community outreach propaganda and the involvement of many volunteers, I’m not feeling the love.

It may just be that I have not myself taken the steps to contribute to Ubuntu – my own fault in a way. But as I have not contributed anything to Debian either, aside from supporting my fellow users, religiously reporting bugs and spreading the gospel, I still feel like I’m part of it. When I install Debian, I have a sense of using a system that I really own and control. It is not a matter of tools – Ubuntu is still essentially Debian and it features most of the tools I’m familiar with… So what is it ? Is it an entirely subjective feeling with no basis in consensual reality ?

It may have something to do with the democratic culture that infuses Debian whereas in spite of Mark Shuttleworth‘s denials and actual collaborative moves, he sometimes echoes the Steve Jobs ukase style – the “this is not a democracy” comment certainly split the audience. But maybe it is an unavoidable feature of his organization: as Linus Torvalds unapologetically declares, being a mean bastard is an important part of the benevolent dictator job description.

Again, I’m pretty sure that Mark Shuttleworth means well and there is no denying his personal commitment, but the way the whole Canonical/Ubuntu apparatus communicates is arguably top-down enough to make some of us feel uneasy and prefer going elsewhere. This may be a side effect of trying hard to show the polished face of a heavily marketed product – and thus alienating a market segment from whose point of view the feel of a reassuringly corporate packaging is a turn-off rather than a selling point.

Surely there is is more about it than the few feelings I’m attempting to express… But anyway – when I use Debian I feel like I’m going home.

And before you mention I’m overly critical of Ubuntu, just wait until you hear my feelings about Android… Community – what community ?

Brain dump and Politics and Technology08 Nov 2010 at 1:42 by Jean-Marc Liotier

Evil implies that corporations can be judged as humans, but they are not : corporations are just soulless. They knows neither right nor wrong. By definition, a corporation exists merely as a maximization function toward the goals of its shareholders. That is why, in spite of having legal personality, corporations cannot exist in the political sphere that holds control and oversight in the name of the public good – though the extent to which the financial resources of corporations are employed to influence political campaigns shows how poorly that separation of power is applied.

Charles Stross’ Accelerando is heavily loaded with buzzwords – though it is a fun read and a great reflection on post-humanity. Among the interesting concepts that pepper the story, I found the “Turing-complete company constitution” – if you have legal personality, then why not Turing completeness ? And then why not go all the way to human-equivalent sentience and cognitive abilities or better ? You may, but it won’t matter because whatever their sophistication, corporations have a mandate inscribed in their lowest level code that merely makes them paperclip maximizers.

Whether you consider them anthropomorphic artificial intelligences or just really powerful optimization processes, corporations don’t care about you anyway. To paraphrase Eliezer Yudkowsky : they don’t hate you, nor do they love you – you just happen to be resources that they can use for something else.