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Voice Over IP On Wireless Mesh
infractor writes "ZDNet is reporting that the Linux based LocustWorld Mesh system now has SIP routing at every node. The LocustWorld boxes have been widely used in community broadband projects where DSL is not available, so successfully that they have been seen as a threat to next generation mobile networks. With the addition of VoIP support, these mesh networks can now compete with the telcos on voice as well as data services. More details here."
the kind of "wireless internet" that I have been babbling about in other threads. This is what can liberate us from corporate control of internet access. I want to see this "wireless cloud" cover the planet. The latency issues will be worked out. In the meantime, this is great for "little" community internets where latency is not that bad. Even if they can't access the net at large, they can communicate, completely free from interference from the gov't, with each other. Maybe (hopefully) it can bring about completely anonymous, untracable communications. Just because it's not codified into law, anonymity is a right, and anything that can bring it about is a good thing.
What?
I've always thought that this should be. Wouldn't it be great if wireless networking were as easy to come by as electricty, but without the wires.
I know it's a little communistic in thinking, but I really believe that to gain true freedom of information, we need to make the information superhighway free to use.
While I know many problems would have to be worked out, like security, but it would change everything. Imagine every student being able to turn in assignments anywhere. Imagine doctors being able to monitor patients real-time, as they were being rushed to the emergency room. Yes it would put the telcos and cable companies in an uproar. But I think that would be the price of progress.
So long as this is internet to internet there is no service fee.
However, this sort of thing, if it becomes common, could quite possibly lead to a tragedy of the commons. If everyone actually started using all the bandwidth they had available, the networks would become jammed quickly enough.
Free VOIP is great in the short-term, but there is *not,* at this point, an unlimited amount of free bandwidth available.
I'll shut up after this, promise. :-)
:-) There are also extensions to the ad-hoc routing protocols (like passive monitor of route info between other clients in DSR) that could be supported if only the hardware was open enough to do so.
... and a pony!
Multisecond RTT doesn't happen on anything but GPRS
I've seen it far too often on congested wifi networks. you easily get into a congested state with a crowded AP that forces lots of client waits for the DCF (i.e DIFS + padding, each in turn) and also induces lots of retransmission at the physical level due to collision with so many clients trying to talk to the same AP. Low power clients associated at the 1 or 2 Mbps rates drive this contention over the DCF even higher, severely punishing everyone associated.
The big conference venues are notoriously bad about this, as you often end up with 10-20+ people associated with a single access point. That is just too many, and the 802.11 MAC was never meant to handle that kind of load efficiently. It is a pretty good solution for the general case that simply can't cover all the edge cases (long shots, high client loads, noisy RF environments).
This type of situation results in really weird ping times, for example. I've seen fluctuations myself that go from 80ms, 120ms to 3s!, 2s!, etc. then back down to a few score milliseconds. That is the 802.11 MAC trying to cope with scenario's it was never designed to encounter.
I mentioned software radios in the first post because having access to timing and congestion control in the MAC would allow mesh boxes, clients, and AP's to make very significant performance enhancements for situations where they were needed. Why be forced to use a static, inflexible, proprietary hardware layer when you can have the open flexibility associated with software radio? (It's coming, just not soon enough
I don't want to bitch too much; we have come a long way from sub-megabit data via FHSS over 900Mhz. I just want the really good stuff to hurry up and get here already so that things like mesh networks, low latency/loss voice over IP, and highly available multipath/redundant network configurations can be enjoyed to their full potential. (software radio + multiple input / multiple output + intelligent network stacks that can handle a diverse and volatile network environment).
Gratuitous links:
congestion problems at TechEd conference
congestion melt down at CeBIT
GNU Radio's software defined radio (SDR)
software defined radio on $2,000 of 'roids [it's a dev kit, but would work very well for almost any kind of project]