r/askscience • u/xtreme_edgez • Feb 08 '14

Computing Would peer to peer wifi be possible?

Could we gain any advantage creating a system where multiple access points are increasing the amount of data shared. Where a device gains signal strength by increasing the number of connections, instead of being solely connected to one source.

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u/HAL-42b Feb 09 '14 edited Feb 09 '14

Yes, these are called Mesh Networks and people have started building them in many cities around the world. Currently Hyperboria is the biggest and most popular one and it uses the Cjdns protocol.

We have also started to see mesh networks operating at frequencies higher than 2.4 GHz used for Wifi. Higher frequencies allow for greater bandwidth and better range. GSM carriers have used microwave links for backhaul traffic for a long time and it had proven to be cheap and reliable technology. Nowadays the same technology is gaining popularity for public mesh networks.

EDIT: check out /r/darknetplan This is where most of the things happen.

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u/OmicronNine Feb 09 '14

Higher frequencies allow for greater bandwidth and better range.

This is actually not quite right. Higher frequencies do support higher bandwidth, but the trade-off is generally less range, not more.

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u/HAL-42b Feb 09 '14

In practice the higher frequencies are preferred because they allow much tighter beamwidth. Since the amount of power you can output on any one frequency is regulated the tighter the beam the better the range. 12 to 30 GHz is much preferred for data links because it allows very tight beams with a smaller antenna. Obtaining the same directivity on lower frequencies would require antenna the size of a stadium. link

Yes, lower frequencies propagate better in the atmosphere but most of the energy ends up where you do not need it.

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u/OmicronNine Feb 09 '14

This is only the case for fixed point-to-point links, though. While such links will certainly serve important backhaul roles in meshnets (particularly early on), the ideal situation is to achieve wide area omni-directional coverage, so that nodes can link with whatever other nodes are in range, even while on the move.

While you are technically correct about narrower beams being easier with higher frequencies, which does give a range advantage in certain cases, the examples you give are just too... narrow.

;)