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Say we have a router (capable of 802.11 protocols) and some number of devices that are configured to communicate with this router. I have learnt about how devices/nodes use CSMA/CA to transmit data, and other mechanisms such as RTS/CTS & NAV, to help prevent collisions in the wireless medium.

However, I haven't been able to find an answer to a subtle issue. If one device intends to communicate with another device, then would it be possible for the devices to communicate directly with one another (assuming they are within each other's range)? Or would they still have to send packets via the router?

I just feel that a significant latency is introduced if the devices have data to send to each other, but have to still route packets through the router. The same CSMA/CA scheme could be used to coordinate transmissions between the devices directly.

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    \$\begingroup\$ When you ask "would it be possible for the devices to communicate directly with one another", do you mean "Does something in the current suite of 802.11 protocols support this" or "Is it possible to design a new protocol stack that could do this"? \$\endgroup\$ – Joren Vaes Apr 10 '17 at 14:11
  • \$\begingroup\$ I'm asking whether current 802.11 standard supports direct transmissions between devices on the same subnet. \$\endgroup\$ – V-Red Apr 10 '17 at 14:13
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    \$\begingroup\$ 'subnet' is a TCP/IP term, but you're asking about 802.11, which is not restricted to only handling TCP/IP. 'subnets' are meaningless at the 802.11 level. Devices with the same TCP/IP subnet could be connected to different APs with different APNs and devices connected to the same AP with the same APN could have different subnets. \$\endgroup\$ – brhans Apr 10 '17 at 14:14
  • \$\begingroup\$ en.wikipedia.org/wiki/Wireless_ad_hoc_network \$\endgroup\$ – Dampmaskin Apr 10 '17 at 14:21
  • \$\begingroup\$ Oh I see. I have rephrased my question. \$\endgroup\$ – V-Red Apr 10 '17 at 14:22
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I think you are looking for Wi-Fi Direct, which allows devices to communicate to each other in a P2P manner, without any access points.

It facilitates connection between the devices over 802.11 protocols.

Latest revision of the specification can be accessed here (it will redirect to the pdf)

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