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I have a bluetooth mouse and a bluetooth keyboard.

When I press a key and move the mouse at the same time, it works. But how ? How does the bluetooth chip doesn't get confused by two signals at the same time ?

Note : keyboard/mouse is an example but I don't care especially about this (because a key press is so short maybe), more about the general underlying concept of how 2 bluetooth peripherals can talk to a computer at the same time. Thanks!

P.S I don't know to what Stack Exchange this question belongs too, feel free to move it

  • Bluetooth devices have unique addresses that look like Ethernet MAC addresses - they are both 12-digit hexadecimals. Unique addressing prevents collision of signals. See help.ubuntu.com/community/BluetoothSetup for some more info. – Marios Zindilis Jun 16 '15 at 8:52
  • For the correct site, try superuser.com I guess but a question about how two radio devices manage to transmit signals without interfering with each other is almost a electronics.stackexchange.com question... All I know is that with all the radio devices around me right now from mobile phones to wifi to FM radio to wireless doorbells, it somehow all works, otherwise modern life would be quite different! – Celada Jun 16 '15 at 8:57
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Basically it works because bluetooth is a network like wifi. Each device participates in that network. It's not like two walkie-talkies where one can interfere with another so operators need to take turns. (It is on the low level, but more later) Instead, it's like a wifi-network where each device participates (takes turns).

Just like a wifi network, if one bluetooth device is sending a lot of data, then the other devices will need to wait. Your keyboard and mouse are less effected because they have short bursts of data. If you were to have, say a bluetooth speaker, a mouse, a keyboard, and a bluetooth hard drive all talking to the same computer, then your speaked and hard drive connections would go slower, and your mouse/keyboard would be less responsive.

Keep in mind that most bluetooth setups only contain 1-2 devices. It's not really a good choice for high data throughput, ormany device connections. It is however a good choice when just sending a tiny amount of data, or when just connecting to one thing. This limitation is why bluetooth hard drives, buletooth monitors, and bluetooh printers are not very popular, while their wifi counterparts are.

https://developer.bluetooth.org/TechnologyOverview/Pages/Topology.aspx Should help you understand.

Keep in mind this answer is high level and doesn't really look at protocols over bluetooth, or other "extensions" that work to solve these limitations.

  • You say "like a wifi network", ... that's why bluetooth hard drives are not popular.... that's why their wifi counterparts are. But if Bluetooth acts the same way as wifi, why isn't their this problem on wifi ? – Thomas Nov 7 '15 at 8:35
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    It's complicated, but basically, because when you use a wifi hard drive you "know" it's going to be slow, and you accept that it's going to slow down your whole network. Where with bluetooth it's not ok for your keyboard to slow down, when you copy a file. – coteyr Nov 8 '15 at 3:12

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