A method includes determining, by a first radio transceiver of an access-restricted environment, of first direction information of a first radio signal transmitted between the first radio transceiver and a wireless device. The method further includes determining, by a second radio transceiver of the access-restricted environment, of second direction information of a second radio signal transmitted between the second radio transceiver and the wireless device. The method further includes receiving, by the access-restricted environment, of angle information determined by an electronic key associated with the access-restricted environment. The method further includes determining, based on the first direction information, the second direction information and the angle information, whether the wireless device is a relay device or the electronic key. The method can be based, for example, on a Bluetooth technology.