In wireless communications, unlike cables that require a mere plug in, there is a shared medium that allows two ends of a connection to know each other before any interchange of data can occur. This implies prompting a device to search for other devices within its proximity to connect to, automating the sequence in that the next time the devices get within range of one another, this process just happens without intervention.
This is what we know as pairing.
It seems close to simple but it actually takes some time for a device to discover others. It is even made difficult if there are multiple devices within its range, and the automatic pairing after the first time will not effect if you are pairing with a device that you will never use again.
This is how NFC joins the race. NFC was first developed by Sony and NXP Semiconductors invented the later technology we see to-date, which enables short range communication between compatible devices while sending data over radio waves.
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It can not exceed four centimeters, in comparison to Bluetooth which can reach up to thirty feet. One would take it for a disadvantage but close proximity is also an advantage when it comes to prevention of interference. In crowded locations where there are many devices trying to connect to each other, NFC can quickly connect two devices close to each other then shift the signal on to Bluetooth so that the device holders can move any further without breaking the connection.
This strict proximity ensures that exactly the two devices that you would wish to connect are the ones linked up. It is just enough to allow two Bluetooth devices to identify one another and establish a secure connection, a reason for Bluetooth device manufacturers opting to use NFC for Bluetooth pairing.
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For instance, to connect your Bluetooth headphones to your smartphone, you just need to make sure that the headphones are powered on, your phone is unlocked and that both Bluetooth and NFC are enabled. Then tap the devices together, and you are good to go. You may need to ensure that both your phone and the headphones support the tap-to-pair functionality.