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In the 802.11 protocol broadcast happens at minimum speeds (usually 1 Mbps) since there is no ACK system to know if the packet has been delivered successfully.

But I want to broadcast a video stream and higher error rates are not a problem for my application, and I would prefer higher speeds to lower error rates (I will handle the error correction on higher layers with my own codes).

I have set up an access point using "Hostapd" and a 802.11n wifi dongle in linux on a raspberry pi 2 and wanted to know if there is a way to change the broadcast speed limit so I can do the broadcast in higher speeds.

Update 1:

I tried removing the lower speeds in Hostapd by adding

supported_rates=240 360 480 540
basic_rates=240 360 480 540

But still broadcast is happening at 1Mbps.

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The 802.11 standard leaves multicast/broadcast rate selection up to implementers. So that means it's probably up to the card/firmware/driver of the WNIC you're using.

That said, hopefully your WNIC is smart enough to not try to send multicasts or broadcasts using a rate that's not marked as a Basic Rate. The Basic Rate set is the set of rates that all clients of your AP must support in order to associate to (i.e. connect to) your AP. If you have a way to specify your Basic Rate set in hostapd or in your WNIC driver, that might be a way to do what you want.

Note that increasing the multicast/broadcast rate decreases the effective range of your network. If a client can't receive ARP broadcasts, it's basically not on the network (unless you program static ARP mappings on all the devices on that network that need to talk to that client, or have a router do Proxy ARP routing and ICMP Redirects).

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  • Thanks, I'll try that to see if I can set the basic rate and see if that works. – Scarlet Jul 30 '15 at 21:02
  • I tried it even with limiting the basic rates but the broadcast is still happening at 1Mbps. I guess it is hardware dependent whether we can remove the lower speeds or not. I'll put the details in the question. – Scarlet Aug 4 '15 at 21:22

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