Why are Bluetooth pairings/connections sometimes dodgy unlike wifi which almost connects instantly?
In: Technology
The two technologies work in completely different ways and are optimized for different purposes.
With WiFi, you have an access point which is normally wired to a power outlet. It is continuously broadcasting its presence to anyone listening – about 10 times per second. The only thing a device has to do connect to it is look through all the channels until it finds the access point, then connect. It only has to spend about 1/10-2/10 of a second on each channel seeing if it finds an AP, so this can go pretty fast. There are 13 WiFi channels in the 2.4GHz band. If you’re always on the same AP, it’s likely the device will know what channel to expect it on to make the process faster. Once the device finds the AP then the connection process is quite fast (just a few packets of data quickly exchanged), if everything is working smoothly (though some routers and other WiFi APs are slow).
Bluetooth is designed for connecting between low-power devices, so it works differently. Bluetooth devices aren’t transmitting all the time. They aren’t even receiving all the time, as even that would use too much power. Instead, Bluetooth devices “wake up” periodically, every 1-2 seconds, and see if anyone is calling out their name. They switch channels every time, and there are 32 possible channels. Since Bluetooth is a lower power technology, it relies on switching channels constantly, avoiding noisy channels – but this only works after devices are connected. Initially, you get a random channel that changes every second or so, and if you get a bad roll of the dice, it can be too noisy for the connection to work, so you get to wait. And the device that is making the connection has to transmit constantly until it “catches” the receiver turning on and listening. And that is just for actively connecting to an existing device. If you’re scanning for devices it’s worse.
That said, it’s entirely possible for Bluetooth to be fast and WiFi to be slow. It depends on the exact specific situation, the devices involved, how noisy your RF environment is, etc. It’s also entirely possible that your problems are caused by outright bugs or problems with your devices.
Bluetooth requires less power, emits less powerful signal, while wifi creates higher frequency so needs more power to connect, in turn making a more powerful signal.
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