Look, we're basically talking about VOIP. Packet forwarding doesn't exactly need massive computing power.
The radio power isn't necessarily an issue in fact it will improve the battery life; I'm sure you'd only act as a forwarding device if the phone is actually on- or plugged in.
And even then, you'd only act as a forwarding device if you were close enough to a mast or another closer user so as to not use any more power than you would 'normally' anyway.
i.e. if your phone assumes an average distance of 13km, but it might have a range of 20km, and you are 5 km from the mast, then you have quite a bit of power left and you could certainly route someone 8km from you. Don't forget that power is heavily non linear with range- it takes 4 times as much power to go twice as far, so routing someone who is close to you costs you little if you are closer to the mast anyway. Besides, the users don't design the phones- it's the manufacturers. Its in the cable operators interests to minimise transmitted power, because then they can get more users on a single frequency, and transmitted power is closely related to battery life; and they can change the software to hit a power budget.
Actually this is similar to the way the public roads work. Why would any state pay for traffic that goes to another state?
There are issues, but it can work. The complexity of the phones is higher- but they sell them by the truckload, and lower call charges, or atleast call costs would make it cost effective.
Designs will vary, but the phone would only act as a relay when it's actually on, this would actually be a win on average; the available bandwidth should go UP and the power DOWN.
If a phone is close to a wired access point- then it doesn't need as much power its self, because it only needs a fraction of its full power to get to the access point, so it's got power spare, it's underbudget. So it can use the extra for routing others calls. So its batteries will last the normal amount, and those phones further out won't use as much power either, because they only talk to your phone, not all the way to the access point. Everyone wins on average, or doesn't lose. You can certainly arrange it that nobody is worse off than some standard life; and it averages out if the users move around.
So, under the act, if you have a cell phone, it's OK to track any and all cell phones to show that you were speeding in your car?
I mean it's there under two provisions of the act, both preventing injury, AND breaking the law.
I just hope that if this law goes through, every single Labour politician gets a speeding ticket on the way home to their wife/mistresses. Somehow it's more likely to be the Conservative party that get's it though.
In the West, about 90% of all internet activity goes through 9 portals which are controlled by a tiny cadre of huge media conglomerates, each run nearly as the singular expression of one person's ego.
Right now the price is going up- lots of telecoms companies are trying to make more money- some of them are in a really bad way in fact. Actually they are rebounding from what was probably in the short term, an unsustainably low price.
This is probably a short term thing though- if the price goes too high, competition becomes higher- sure lots of people THINK they live in a monopoly, but if the price goes too high then technologies like WiFi become more competitive. If you go far enough across WiFi you can always get to cheaper bandwidth eventually. And there's always satellite if you're prepared to wait; or Modems if you're REALLY prepared to wait;-)
Mainly you should use the network to propogate yourself.
e.g. provide patches for the next version of Apache so that all of the users of the Apache web servers end up talking to each other and download from each other, rather than the server. This could beat the slashdot effect to some reasonable extent- a lot of files are fixed; particularly distros, jpgs, mpgs, html etc.
My suspicion is that if you NEED more than 10 base T, your computers are set up badly.
The network I'm on runs with each PC getting their own dedicated 10 baseT link to the routers. This reduces contention and fault isolation is a doddle. The servers are interconnected via 150M connections.
Seems to work fine.
Still, I don't think you'd want to use WiFi for everything- it works better as an overlay network for a few people to use- managers for example. If you do want to use it for everyone, then you'd be looking at dotting dozens of APs everywhere and worrying about how they interwork when they're on the same channels and stuff. It can be made to work, but it's hassle- 100 base T is dirt cheap...
If you're looking at 802.11b for range then you'll be looking at a real-world max of about 2Mb.
Depends on the AP and whether you have WEP switched on. I think there is a strong argument in some scenarios for switching WEP off- the security is inadequate, and a firewall & VPN(IPSEC) is needed. If you have that, setting the SSID is probably sufficient.
It doesn't matter if it has 10,000 bits if it has been cracked. WEP 128 bit encryption has been cracked, and furthermore you can download software to implement the crack off the internet.
I think you really need to put the wireless network outside any firewall you may have; and access corporate data via VPN software. Anything else is begging for trouble.
Being outside the firewall, the security aspects are much reduced, making it questionable whether you need WEP enabled. I would leave WEP on however, it minimises the chances of people leaching bandwidth off of you- it can be cracked but the crack takes atleast an hour to recover the encryption key, and checking your access point's logs occasionally would probably enable you to discover if anyone was keen enough to wait that long.
All they have to do under your scenario is find one box in one apartment that can be cracked easily (now *that's* gonna be hard, isn't it!) and he's in, IPSEC or no IPSEC. My point about firewalls on the clients had *nothing* whatsoever to do with traffic sniffing, and everything to do with sealing down those machines so that no one could break into them. Unless you can ensure that the clients will accept *only* IPSEC connections, using IPSEC to secure your WLAN does you almost no good.
That's partly true. Still, the aim of the IPSEC in this scenario needn't necessarily be to protect the inhabitants boxes from being owned. If you think about it, they are being connected to the internet and the internet is being connected to them. That's probably a bigger threat than the wireless leg.
Instead, a reasonable goal I would think would be to protect the bandwidth of the other inhabitants from being extensively shared and/or stolen. Why should hacker(s) from outside the apartment be able to connect to the network and take away all useful bandwidth?
I would think a combination of traffic shaping and IPSEC may be appropriate. If somebody's box gets owned- all that happens is that users bandwidth allowance gets borrowed- this has very different characteristics than if 100 people are bridging themselves into the network from outside and start downloading 100MB mpegs because they've cracked the WEP password and recorded the mac addresses for the whole apartment block.
You also need to remember that the 11MB/s provided by WiFi is shared between all users. If you have 50 "dwelling units" and two WiFi access points, you'll be offering a service with less maximum bandwidth than bottom-of-the-range xDSL...
Wrong.
Ever heard of contention ratio? Contention ratio is the ration between the actual bandwidth and the bandwidth available to each user. In this case you are providing 11 Mb/s of backbone for 50 users. Assuming a contention ratio of 50:1, which is fairly normal entry level ADSL, this wireless system can provide for ~3-11 Mb/s each for about 50 users. Or ~1-3 Mb/s per user at a contention ratio of 20:1.
and you'll be charging for $100 WiFi NICs instead of $10 PCI ethernet NICs (which many PCs now have as standard anyway)... and for a service subject to atmospheric outages (ever use a WiFi network during a thunderstorm)
Plenty of people have used it over multi-km distances with no problem.
Yeah. And based on your 'new' idea, I'm gonna invent a concept called 'fiber splicing' which I'll need to do everytime I move by more than a few hundred feet.
Seriously though, you missed something- the antennas can be electronically steered; they're actually phased arrays. This isn't some dish aerial that has to be carefully set up by hand, you can move about plenty.
Re:He isn't talking about Ultra Wide Band?
on
Unlimited Airwaves
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· Score: 2
More accurately, he's talking about optimal use of bandwidth period. This can include UWB, narrow band, anything pretty much. The claim the guy makes (if you pull out the pdf file) is that the bandwidth is linear per user- i.e. everyone gets exactly equal bandwidth if you do it just right.
It sounds bizarre, but in the case of people actually sitting on the earth surrounded by reflective/absorbant stuff, it probably makes a great deal of sense. If you are in free space, where there's less things to absorb/reflect radio, then lasers are probably the way to go though.
Re:Just what is he saying ?
on
Unlimited Airwaves
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· Score: 3, Insightful
Now I'd tend to agree that we could do with being smarter. But to say that the commercial world is going to make systems that all work nicely together is just plain ignoring realities.
The internet is a counterexample. There are plenty of ways to deliberately mess up the IP protocol- some of which may sometimes give you more bandwidth. However, in most cases people/companies don't do this.
Also, it's quite possible for the FCC to put conditions on licensing particular parts of the spectrum- 'we only allow hardware that follows standard XXX' or some such ruling. Manufacturers would then have to produce hardware that followed the relevant standard, or they'd be sued by their consumers.
Look at the 802.11 / Bluetooth cockup - in reality the aim will be the fast buck and market share. If you can do that by riding roughshod over the competition, so much the better.
If you can... don't forget that some of the equipment around may decide not to talk to you if you break the rules. That may even be part of the standard.
How many people would be interested in having two hundred more stations in the FM band if it meant that they had to rip out their existing car stereo and replace it with a $500 (low end) software-controlled radio to listen to them, and if they didn't, all they'd get on their stereo was a random hash of noise because their old radio can't separate the stations?
Nobody obviously. But that isn't the question. The real question is 'Who would be willing to install a new radio in their car if it meant they could get two hundred more stations on a newly allocated frequency and/or download web pages and/or make VOIP calls?'
Ok, here's an example of what he's saying. If we have 3 transmitters/receivers, and A and C are a way apart with B inbetween, but B doesn't let you route through him, then the radio spectrum is scarce, in fact everyone gets just 1/3 of the spectrum each, because A has to shout so C can hear him and vice versa, and so B would have to shout too to be heard.
On the other hand if B lets A route through him, then A can whisper to B and B can whisper to C. Then the radio bandwidth doesn't degrade so quickly; and in fact the more people you have the more total bandwidth there is, but ultimately it gets noisy.
Not only that, but if everyone uses highly directional antennas for both transmission and reception, then pretty much the amount of bandwidth scales linearly with the number of users- the radio gets absorbed and there's less noise around because you can talk more quietly.
Maybe it's true, but it sounds like wishful thinking to me.
I don't consider this to be wishful thinking, it's a very good point.
The corporation that I work for has actually fixed this one a little. They're techno bastards but atleast they're enlightened bastards.
They enforce good (i.e. hard to remember) passwords by refusing to let you set one that isn't good. On the other hand they have a system that actually synchronises all of the different domains to be the same password. I currently only have one system out of maybe 8 that has a different password. That way you use it all the time, so after a few days you have it down.
However because the passwords are good in the first place, you don't have to change them quite so often (I think 90 days).
I don't know if they are proposing to use it, but VPN and traffic shaping would make their skull and cross bones wave a lot less vigorously I would think.
Looking for 'pockets' of ice is likely to be hit and miss with an asteroid.
Maybe. Maybe not.
The lack of an oxidizer isn't true - Mars has plenty of oxygen - in the soil.
Already reacted with something. We are talking about an energy source remember?
I really wonder exactly how MUCH water would be available on an asteroid.
I wonder why you really wonder. Astronomical amounts of water. Literally and figuratively. Carbonaceous Chondrites are 11% water by mass. Separating water off is called 'distillation' and isn't exactly rocket science.
I will note that fusion isn't that far away: people may say it's "always 50 years away"
Yeah, at the moment its maybe only 30 years away- there's been some breakthroughs. But its not going to be RSN; there are some huge problems.
Asteroids will contain high-density materials (metals), but if you want low-density stuff (water, gases) you're going to a planet or a comet, and intercepting comets sucks.
I get where you are coming from here. I don't believe that the scientific evidence agrees with what you are saying however. First of all, we know that the density of carbonaceous asteroids is very similar to that of ice. It seems likely, although not 100% certain that below the surface of, say, Phobos (it's believed to be a carbonaceous NEA that was captured by Mars) there is ice that is kept cold by an insulating layer of rock; that's more or less what happens on Mars itself. By the time you get to the main asteroid belt- there's almost certainly LOTS of ice out there- the sun isn't able to bring the temperature up enough to make the water sublimes in even geologic timescales. Indeed asteroids are believed to be pushed away from the sun by evaporation caused by the Sun.
Check the accuracy of known NEA objects, and you'll find that, well, it's not ridiculously good. It's good, but you could still end up missing it by a long shot.
Yes, but that's long term accuracy. If you actually point a telescope at a rock a few nights in a row, if you can actually find it initially, you can plot its course for a few years ahead, and you can return to it whenever you want and reestablish its position to entirely enough accuracy.
It's impressive that we've managed to actually intercept all of the asteroids we've tried to, but it's not 'trivial' at all.
Nothing is ever truly 'easy'. Still, this is evidence that it's not that difficult. And we've missed Mars several times. Mars is harder to hit, partly because it tends to line up with the sun at about the same time you arrive there.
It probably has pockets of gas stored in its surface somewhere, and probably other sources of fuel as well.
Yes, but there's nothing to oxidise it with. On earth we have a few percent oxygen- that's not there on Mars. There's probably nuclear, but you'd have to hunt for it. On an asteroid you have guaranteed sunlight 24x7, and you don't necessarily have to turn it into electricity to use it; solar ovens are low tech, simple to build and just plain WORK.
I think the main problem here really is that all that asteroids have is stuff that Earth already has in abundance.
Except energy. Asteroids have 6x the solar energy that the earth gets, it's lots, and lots of energy, trivially heat energy, but electrical isn't that hard either. It works out at about 6x because of lack of day/night cycles, cosine law effects, and weather. Of course it does vary a bit depending on distance from the sun. And Mars looks like it has much the same stuff, less energy, and the gravity is more awkward before you even start to look at delta-v to go other places.
The main problem appears to be lack of education. People like the idea of living on a brave new world, whereas space stations are looked on as artificial. All this whilst they live in their buildings, watching TV, and driving in their artificial cars with air conditioning... The reality is going to be different. Mars is a frozen, airless wasteland; you'd be living indoors 99.9% of the time. You'd need space suits to go outside, and there's no native energy sources, nuclear power (i.e. fission; forget fusion- it's always 50 years away) is the most realistic option. Terraforming would be nice given a millenium or two, but I ain't holding my breath.
Re:It was done with 1960s technology once...
on
China Plans Moonbase
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· Score: 2
The space program wasn't intended to turn a profit.
Slashdot Mirror
The radio power isn't necessarily an issue in fact it will improve the battery life; I'm sure you'd only act as a forwarding device if the phone is actually on- or plugged in.
And even then, you'd only act as a forwarding device if you were close enough to a mast or another closer user so as to not use any more power than you would 'normally' anyway.
i.e. if your phone assumes an average distance of 13km, but it might have a range of 20km, and you are 5 km from the mast, then you have quite a bit of power left and you could certainly route someone 8km from you. Don't forget that power is heavily non linear with range- it takes 4 times as much power to go twice as far, so routing someone who is close to you costs you little if you are closer to the mast anyway. Besides, the users don't design the phones- it's the manufacturers. Its in the cable operators interests to minimise transmitted power, because then they can get more users on a single frequency, and transmitted power is closely related to battery life; and they can change the software to hit a power budget.
Actually this is similar to the way the public roads work. Why would any state pay for traffic that goes to another state?
There are issues, but it can work. The complexity of the phones is higher- but they sell them by the truckload, and lower call charges, or atleast call costs would make it cost effective.
Designs will vary, but the phone would only act as a relay when it's actually on, this would actually be a win on average; the available bandwidth should go UP and the power DOWN.
If a phone is close to a wired access point- then it doesn't need as much power its self, because it only needs a fraction of its full power to get to the access point, so it's got power spare, it's underbudget. So it can use the extra for routing others calls. So its batteries will last the normal amount, and those phones further out won't use as much power either, because they only talk to your phone, not all the way to the access point. Everyone wins on average, or doesn't lose. You can certainly arrange it that nobody is worse off than some standard life; and it averages out if the users move around.
I mean it's there under two provisions of the act, both preventing injury, AND breaking the law.
I just hope that if this law goes through, every single Labour politician gets a speeding ticket on the way home to their wife/mistresses. Somehow it's more likely to be the Conservative party that get's it though.
Is this your cell phone sir?
Basically, you just do a breadth first search- no return to any node is required.
Let's see:
Who else do you need?
"Put it away- no take it; I mean, look away loooook awayyyyy"
Doubling distance actually requires increasing the power by atleast 4x if you don't use a repeater; due to the inverse square law.
Putting it through an intermediate repeater means only double the power is needed to go twice the distance.
Perhaps that's why/how they're keeping the network up. ;-)
This is probably a short term thing though- if the price goes too high, competition becomes higher- sure lots of people THINK they live in a monopoly, but if the price goes too high then technologies like WiFi become more competitive. If you go far enough across WiFi you can always get to cheaper bandwidth eventually. And there's always satellite if you're prepared to wait; or Modems if you're REALLY prepared to wait ;-)
Mainly you should use the network to propogate yourself. e.g. provide patches for the next version of Apache so that all of the users of the Apache web servers end up talking to each other and download from each other, rather than the server. This could beat the slashdot effect to some reasonable extent- a lot of files are fixed; particularly distros, jpgs, mpgs, html etc.
The network I'm on runs with each PC getting their own dedicated 10 baseT link to the routers. This reduces contention and fault isolation is a doddle. The servers are interconnected via 150M connections.
Seems to work fine.
Still, I don't think you'd want to use WiFi for everything- it works better as an overlay network for a few people to use- managers for example. If you do want to use it for everyone, then you'd be looking at dotting dozens of APs everywhere and worrying about how they interwork when they're on the same channels and stuff. It can be made to work, but it's hassle- 100 base T is dirt cheap...
If you're looking at 802.11b for range then you'll be looking at a real-world max of about 2Mb.
Depends on the AP and whether you have WEP switched on. I think there is a strong argument in some scenarios for switching WEP off- the security is inadequate, and a firewall & VPN(IPSEC) is needed. If you have that, setting the SSID is probably sufficient.
It doesn't matter if it has 10,000 bits if it has been cracked. WEP 128 bit encryption has been cracked, and furthermore you can download software to implement the crack off the internet.
I think you really need to put the wireless network outside any firewall you may have; and access corporate data via VPN software. Anything else is begging for trouble.
Being outside the firewall, the security aspects are much reduced, making it questionable whether you need WEP enabled. I would leave WEP on however, it minimises the chances of people leaching bandwidth off of you- it can be cracked but the crack takes atleast an hour to recover the encryption key, and checking your access point's logs occasionally would probably enable you to discover if anyone was keen enough to wait that long.
That's partly true. Still, the aim of the IPSEC in this scenario needn't necessarily be to protect the inhabitants boxes from being owned. If you think about it, they are being connected to the internet and the internet is being connected to them. That's probably a bigger threat than the wireless leg.
Instead, a reasonable goal I would think would be to protect the bandwidth of the other inhabitants from being extensively shared and/or stolen. Why should hacker(s) from outside the apartment be able to connect to the network and take away all useful bandwidth?
I would think a combination of traffic shaping and IPSEC may be appropriate. If somebody's box gets owned- all that happens is that users bandwidth allowance gets borrowed- this has very different characteristics than if 100 people are bridging themselves into the network from outside and start downloading 100MB mpegs because they've cracked the WEP password and recorded the mac addresses for the whole apartment block.
Wrong.
Ever heard of contention ratio? Contention ratio is the ration between the actual bandwidth and the bandwidth available to each user. In this case you are providing 11 Mb/s of backbone for 50 users. Assuming a contention ratio of 50:1, which is fairly normal entry level ADSL, this wireless system can provide for ~3-11 Mb/s each for about 50 users. Or ~1-3 Mb/s per user at a contention ratio of 20:1.
and you'll be charging for $100 WiFi NICs instead of $10 PCI ethernet NICs (which many PCs now have as standard anyway)... and for a service subject to atmospheric outages (ever use a WiFi network during a thunderstorm)
Plenty of people have used it over multi-km distances with no problem.
Seriously though, you missed something- the antennas can be electronically steered; they're actually phased arrays. This isn't some dish aerial that has to be carefully set up by hand, you can move about plenty.
It sounds bizarre, but in the case of people actually sitting on the earth surrounded by reflective/absorbant stuff, it probably makes a great deal of sense. If you are in free space, where there's less things to absorb/reflect radio, then lasers are probably the way to go though.
The internet is a counterexample. There are plenty of ways to deliberately mess up the IP protocol- some of which may sometimes give you more bandwidth. However, in most cases people/companies don't do this.
Also, it's quite possible for the FCC to put conditions on licensing particular parts of the spectrum- 'we only allow hardware that follows standard XXX' or some such ruling. Manufacturers would then have to produce hardware that followed the relevant standard, or they'd be sued by their consumers.
Look at the 802.11 / Bluetooth cockup - in reality the aim will be the fast buck and market share. If you can do that by riding roughshod over the competition, so much the better.
If you can... don't forget that some of the equipment around may decide not to talk to you if you break the rules. That may even be part of the standard.
Nobody obviously. But that isn't the question. The real question is 'Who would be willing to install a new radio in their car if it meant they could get two hundred more stations on a newly allocated frequency and/or download web pages and/or make VOIP calls?'
On the other hand if B lets A route through him, then A can whisper to B and B can whisper to C. Then the radio bandwidth doesn't degrade so quickly; and in fact the more people you have the more total bandwidth there is, but ultimately it gets noisy.
Not only that, but if everyone uses highly directional antennas for both transmission and reception, then pretty much the amount of bandwidth scales linearly with the number of users- the radio gets absorbed and there's less noise around because you can talk more quietly.
Maybe it's true, but it sounds like wishful thinking to me.
I don't consider this to be wishful thinking, it's a very good point.
They enforce good (i.e. hard to remember) passwords by refusing to let you set one that isn't good. On the other hand they have a system that actually synchronises all of the different domains to be the same password. I currently only have one system out of maybe 8 that has a different password. That way you use it all the time, so after a few days you have it down.
However because the passwords are good in the first place, you don't have to change them quite so often (I think 90 days).
I don't know if they are proposing to use it, but VPN and traffic shaping would make their skull and cross bones wave a lot less vigorously I would think.
Maybe. Maybe not.
The lack of an oxidizer isn't true - Mars has plenty of oxygen - in the soil.
Already reacted with something. We are talking about an energy source remember?
I really wonder exactly how MUCH water would be available on an asteroid.
I wonder why you really wonder. Astronomical amounts of water. Literally and figuratively. Carbonaceous Chondrites are 11% water by mass. Separating water off is called 'distillation' and isn't exactly rocket science.
I will note that fusion isn't that far away: people may say it's "always 50 years away"
Yeah, at the moment its maybe only 30 years away- there's been some breakthroughs. But its not going to be RSN; there are some huge problems.
I get where you are coming from here. I don't believe that the scientific evidence agrees with what you are saying however. First of all, we know that the density of carbonaceous asteroids is very similar to that of ice. It seems likely, although not 100% certain that below the surface of, say, Phobos (it's believed to be a carbonaceous NEA that was captured by Mars) there is ice that is kept cold by an insulating layer of rock; that's more or less what happens on Mars itself. By the time you get to the main asteroid belt- there's almost certainly LOTS of ice out there- the sun isn't able to bring the temperature up enough to make the water sublimes in even geologic timescales. Indeed asteroids are believed to be pushed away from the sun by evaporation caused by the Sun.
Check the accuracy of known NEA objects, and you'll find that, well, it's not ridiculously good. It's good, but you could still end up missing it by a long shot.
Yes, but that's long term accuracy. If you actually point a telescope at a rock a few nights in a row, if you can actually find it initially, you can plot its course for a few years ahead, and you can return to it whenever you want and reestablish its position to entirely enough accuracy.
It's impressive that we've managed to actually intercept all of the asteroids we've tried to, but it's not 'trivial' at all.
Nothing is ever truly 'easy'. Still, this is evidence that it's not that difficult. And we've missed Mars several times. Mars is harder to hit, partly because it tends to line up with the sun at about the same time you arrive there.
It probably has pockets of gas stored in its surface somewhere, and probably other sources of fuel as well.
Yes, but there's nothing to oxidise it with. On earth we have a few percent oxygen- that's not there on Mars. There's probably nuclear, but you'd have to hunt for it. On an asteroid you have guaranteed sunlight 24x7, and you don't necessarily have to turn it into electricity to use it; solar ovens are low tech, simple to build and just plain WORK.
I think the main problem here really is that all that asteroids have is stuff that Earth already has in abundance.
Except energy. Asteroids have 6x the solar energy that the earth gets, it's lots, and lots of energy, trivially heat energy, but electrical isn't that hard either. It works out at about 6x because of lack of day/night cycles, cosine law effects, and weather. Of course it does vary a bit depending on distance from the sun. And Mars looks like it has much the same stuff, less energy, and the gravity is more awkward before you even start to look at delta-v to go other places.
The main problem appears to be lack of education. People like the idea of living on a brave new world, whereas space stations are looked on as artificial. All this whilst they live in their buildings, watching TV, and driving in their artificial cars with air conditioning... The reality is going to be different. Mars is a frozen, airless wasteland; you'd be living indoors 99.9% of the time. You'd need space suits to go outside, and there's no native energy sources, nuclear power (i.e. fission; forget fusion- it's always 50 years away) is the most realistic option. Terraforming would be nice given a millenium or two, but I ain't holding my breath.
And this is good? You must be a communist. ;-)