As it's not 8051-specific, it should be in the 'Chat' section.

You need to search for terms like "RFID" (Radio Frequency Identification), "Contactless key entry", etc

All access-control systems are fundamentally the same - you have some sort of "key", and if the key is "valid" you are granted access; eg

the traditional key is a physical object, which is validated mechanically - it either physically fits in the lock, or it doesn't.

the "key" could be just a code that you have to enter correctly - whether mechanically (as on a traditional safe) or electrically on a keypad - the the validation is a simple match.

the "key" could be more a complex electronic device, and the validation could involve challenges, responses, encryption, etc.

the "key" could be biometric...

etc, etc

"Wireless" is just a way of allowing the key & the validator to communicate...