Hi Oren, First of all, this is not a WiFi mailing list. ARIG is an attempt to find high-layer protocols and management tools for decentralized mesh-structured networks. This is independent of the physical layer, which can be pretty much everything you can use to transmit data with. Yes, we are using WiFi, as it is available and easy to experiment with. Therefore I appreciate the open discussion, as I previously said.
However, please consider the fact that most uses of the 2.4GHz RF spectrum are non-supervised installations in private houses. This includes devices which can be very outdated (microwave ovens, cordless desktop equipment, baby-phones, camera surveillance equipment, ...) and emitting quite a lot of noise in the spectrum. I understand your point as similar to the "making more roads will not lead to lower traffic" argument, which I agree upon. However, even in that analogy, having local-access roads can safe a lot of fuel compared to taking an obligatory loop on the high-way just in order to visit the neighbors (which is what people currently do in regards to telecommunication). On 03/07/2013 12:33 PM, Oren Attar wrote: > A few points to take into consideration: > > 1. Electromagnetic Radiation goes through things and is running 24x7. In non-beaconing networks (-> configuration) and due to power-management schemes, this is only true if the network is actually used. Depending on the software settings, the interval to indicate presence can be very high in non-mobile (i.e. statically mounted devices). Power-management is part of the (though mostly due to concerns about battery life) 802.11n and 802.11s standards. > 2. We're not chewing on network cables. No, but we are exposing them to our living environments, therefore (especially if those soft, flexible, non-conducting, non-flamable plastics are hit by light and/or exposed to warm temperatures) we are breathing and drinking them, not even speaking about producing and recycling them which just happens out of our field of sight. My comment wasn't intended as a direct comparison of tech A vs. tech B, but rather just an illustrative example. > 3. Schumann 7.8hz isn't mighty at all, and that is really the issue. > Its a very delicate field, according to WikiPedia it is 1 PicoTesla or > 10 MicroGauss. ... due to the low frequency this is mostly overlapped by the 50Hz of the power-grid, so maybe speak with them? Yeah right, they don't run a public mailing list open for everyone to discuss which tech they choose. Neither do the mobile phone companies, not even speaking about all the non-public VHF for all sorts of remote-site-surveillance/management... > 4. Using WiFi isn't instead of 3G. Its a "luxury" that is adding more > noise into an already "saturated" environment. Not true. If people got free WiFi, this will reduce the traffic with the (btw very crowded) cellular networks, and as Amir and I previously explained this means the traffic will be wire-bound earlier in the chain, the RF covered distance is shorter, therefore the transmit power can be lower. Generally, I can just agree with what that presentation on optical communication which read like: RF is a rave party. It's crowded out there. > 5. WiFi is by far not a safe technology, and not safer than 3G > transmissions. That is according to my own measurements of field > strength. Please, do the math instead of enlightening us with your conclusions without sharing the data you are basing them on. https://en.wikipedia.org/wiki/DBm Obviously, under ideal conditions, the output of a single 3G handset can be quite low, but due to the omnidirectional antennas and the network being designed for high-mobility (i.e. you move your phone around while you use it, you might even sit in a car or a train while doing that), this leads to much more RF noise in the average case compared to using some fixed directional WiFi installations. Generally, the transmit-power limits (i.e. worst case) of 3G handsets are higher than for WiFi and people are holding them next to their heads while using them. Also, a mobile phone network is obviously more than just the sum of handsets. It also includes base-stations, permanently announcing their presence and operating on a relatively wide frequency band with sometimes thousands of handsets. There are no such extreme local peaks in a flat infrastructure. You are more than welcome to RF meter all of the equipment people are typically using for ad-hoc wifi mesh networks and compare with 3G handsets and base-stations, I'm curious to see the results! > 6. WiFi is a cheaper and less developed technology than 3G which in > normal conditions uses very minimal power for transmission (nowhere > near 250mW). Not true. The recent WiFi standards (802.11n-2010 and for example 802.11s) are very innovative, especially also when it comes to adaptive transmission power, idle-time power-management, "beamforming", ... Power-management in mesh networks (i.e. power-off the transmit-part of the RF chip if there is no traffic and only wake up again if there is a real need for it) is currently a field of active development, implementations (e.g. for ath9k) are being discussed and are piece by piece becoming part of the linux mac80211 stack people are using on OpenWrt-run routers. In the end, this boils down in driver code and configuration, which is up to us to decide upon if it is in our hands (i.e. owning the hardware and using free open source software). > 7. "Directional" WiFi is not a laser beam, it is transmitting a cone > shaped field. Typical opening angles of directional antennas are between 8deg and 20deg, usually 2 or 4 symmetrical ones. So yes, it's not a "laser beam", the signal just creeps around in the targeted area. Having laser would be nicer :) _______________________________________________ arig-discuss mailing list [email protected] https://lists.subsignal.org/mailman/listinfo/arig-discuss
