Slashdot Mirror
Vanu Replacing Cell Tower Equipment With PCs
Dwight Schwartz writes "As reported in an
article on the ScienceDaily site, researchers from
Vanu, Inc. of Cambridge, MA,
have successfully tested a system, the Vanu Software Radio(tm), that can replace a cellular tower's room full of communications hardware with a
Pentium-based computer running Linux. The system
offers the hope of making cellular technology more affordable for small, rural communities." The systems have been tested for the last several months in parts of Texas, with wider adoption planned for the near future.
This is actually *newsworthy*. I was starting to have withdrawls.
This should have a big impact on small towns where expensive cellular equipment isn't cost effective.
You can't legislate goodness. Let each to his own destiny, by will of his freely made choices.
This is excellent. I live in South Africa, and there is a massive gulf between the poor and the few rich - this will help to connect all the poor people, and especially the ones in rural areas.
What makes me the happiest of all, is that the system runs Linux, and this is great in the light of the fact that the South African government has articulated its commitment to open source software (they have indicated that they may replace several government systems with Linux boxes! so I hope that it happenes)
It just shows what a bit of ingenuity can do.
"I hate people who fabricate unintelligent quotes to add to their work seemingly by some 'anon' sage" -- anon
Have a look at the original release from the US National Science Foundation. With some nice pictures. :-)
But is the PC as reliable as a room full of communications hardware? I think not. As soon as your Hard Drive goes out 911 is out of commission.
Not only will this allow cellular rollouts in poorer countries, expect to start seeing this in small pico cell sites across the world. I work for a company that produces network management software, and I know how complex a rollout process for single cell site is. The lists of equipment are huge and costly, and we have an entire set of modules that allow companies to keep track of the hardware in each site and its configuration. In short, cells sites are complex, costly to build and hard to maintain.
Replacing all of that with a tower, antenna and a PC would be a huge saving, both in terms of planing, installation and maintainence. A single site could be rolled out in a matter of weeks, rather than months, and cost a fraction of what it costs now.
For us in Europe, maybe it could help reduce costs and get the debt-laden operators back on their feet. For those of you in the US, you could well see much better coverage on all networks.
GSM is pretty low-bandwidth stuff (around 13kbps). Further, the line cards handle a lot of the framing and general cookery for the interconnects (whether it's a wired E1, or microwave, or whatever). So even a fairly low-end Pentium would handle a few calls. The article does say that it needs a fairly large Linux server, but an ordinary PC would work for a relatively small node. The Digitalk telephone switches we use are really just dual PII-500 machines, and they handle 120 simultaneous wired calls.
Sounds sorta similar to GNU Radio. :-)
It's cool that as computers get faster, you can have software replace hardware
The article seems to basically be saying "we've reduced the amount of kit you need to run a cell" - I'm sure it just removes a tiny portion of the kit needed to set one up though. The article mentions that previously emergency and public calls used separate kit, and that this system uses a PC instead.
So, my bets are: it's replacing a bunch of routers by becoming a software-based router itself, and doesn't handle calls, but merely switches between networks based on call type. All of the other equipment in the cell will still be required. So in essence it reduces the cost, but by no means reduces a cell node to one PC with an aerial sticking out of it.
So the linux boxes are cheap. What about the interconnect equipment? Can a guy off the street spend a few hundred and build his own phone network, or is the marginal cost still significant?
:)
Hell, if it's cheap enough, I'll start my own wireless phone company
Hardware is generally far more difficult to compromise than software, esp' a known operating system (regardless of how much more secure it may be than other cough, doze, boxes) You'd want some very secure remote access if at all. Otherwise you could find yourself with a whole bunch of phones ringing a la lawn-mower man style in a country town near you.
I'm originally from Stephenville, Texas - just down the road from these two communities. There are no third-generation networks available out there. My Sprint PCS phone doesn't work there, either - not even in analog mode. But just 20 miles away I have full signal strength in Vision mode.
I still have some friends in the region using Mid-Tex, and they haven't mentioned anything odd about their service. I guess that means it's a success as far as consumers are concerned.
I'm a student of telecommunications at an university of technology in Finland, and we've had compact basestations gathering dust at a student lab facility for _years_. (one Nokia and one Siemens, if I remember right)
The unit was about two mid-tower cases of volume, had an integrated PC, integrated antennaes, the whole bunch. Everything you need for a GSM basestation. And it really is an old model. Modern models are at least more efficient (with directional tracking antennaes, etc) and more inconspicious (they can look like fake chimneys, parts of wall, etc, so that it doesn't disturb the landscape.)
Probably we're not even talking about the same things since calling a basestation unit a "tower" is ridiculous. Maybe they've replaced the switching centre with a PC? Though I doubt it, since a PC/Pentium would be severely bandlimited to handle thousands of connections. Perhaps with dedicated hardware which is merely controlled by a PC..
The main reason why software defined radio (SDR) hasn't yet taken off is insufficient A/D performance. And it's not the sampling rate that's the issue; A/D's exist now with sampling rates in the gigahertz range.
The bottleneck is in dynamic range -- there can be a large difference between the weakest and strongest signal in an channel (80 dB is one example). To sample with enough resolution to capture that dynamic range, you need a lot of bits. But the more bits you use, the slower you have to sample; it's a tradeoff.
Until A/D converters advance quite a bit more, SDR won't fulfill promise.
The poster should have included this link (pdf) - much more interesting.
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Incremental repeaters are already available. They must be low enough power to fall beneath the regulated power levels of the FCC, generally not more than 4-5 watts, I think.
aceteq.com has some good repeaters, even the 1900 mhz repeaters for US GSM for less than $800. Other systems can be $3000 or more, and can cover larger areas (I've seen some that were capable of 25,000 sq ft.)
So you would have to do a running line of small repeaters to get service to an area, similar to the 802.11 repeaters we've seen here. You might be able to convert it to line-of-sight and do it that way, too.
But the short of it is, it can be done, albeit somewhat expensively.
I'm CTO at Vanu, Inc. Here's some additional info that some posters to this thread have asked about.
- Linux version: we're using a Debian 2.4 release with the real time patches. All the signal processing code runs as an standard application level process.
- A/D and D/A: we're using an external RF front end that provides over 90 dB spurious free dynamic range. The poster who said these are big and hot was right; it's a little smaller than a PC case all by itself, with a hefty fan to dissipate the heat of the power amp. It covers 25 MHz worth of spectrum and costs a lot more than the HP server that does the signal processing.
- software features: the linux applications running on the HP server handle the complete transmit and receive chains. We go from raw digital samples on one side (exchanged with the A/D and D/A converters) to voice and data packets on the other. A separate HP server runs the Base Station Controller functions, which are the protocol logic, handover control, and similar functions.
- reliability: a huge advantage of building the GSM software on top of linux is that it's portable. Some operators want the level of reliability that comes with commercial grade servers; some want the level that comes with telco grade servers. The GSM basestation software runs on whatever they need.
It's great to see how much interest there is in the slashdot community about this.
-john chapin
So if we're now able to make carrier-quality telecom equipment that runs on fairly run-of-the-mill PCs, why are we still paying $50/mo to our mobile phone companies? Think of the revolution that's happening with 802.11, and now imagine a Linksys GSM Router sitting at home next to your Wi-Fi box. Of course our governments would never allow this to take place; who would pay billions to claim stake to the airwaves if we could build our own homegrown networks?
In reality, we'd probably NOT have personal GSM routers as I mentioned above... instead, we'd have community organizations sponsoring local sites, paid for and maintained by their users. Interconnected with other communities, it would form a massive network of telecom co-ops. If linked by microwave, you might not even need to involve your local utilities one bit.
I'm not suggesting that we dismantle the existing mobile networks; however, they are truly OUR airwaves. If we could see to it that a mobile network running on hardware like this were to be built using non- or minimally-licensed (community licensed?) bandwidth, a couple of years of network instability and growth could build a true grass-roots, free-as-in-speech-AND-beer telecom network.
Who's with me?