An access control device, comprising: a first communication interface configured to exchange data with a network node, and a second communication interface configured to exchange data wirelessly with mobile communication apparatuses, characterized in that the access control device further comprises: a wireless power transmission interface, an energy storage and a control unit configured to: check if an active mobile power source unit, which is controlled by a mobile communication apparatus via a master link, is located within an operation range of the wireless power transmission interface, and if so establish, via the wireless power transmission interface, a wireless power transfer link with the active mobile power source unit, and subsequently receive energy from the mobile power source unit via the wireless power transfer link, store the received energy in the energy storage, subsequently send a random number to the mobile power source unit using backscatter modulation, which is to be forwarded to the mobile communication apparatus via said master link, and subsequently receive said random number over a wireless communication link via the second communication interface, and based on the verification of said received random number connect logically with the mobile communication apparatus over the wireless communication link, and subsequently exchange data with the mobile communication apparatus over said wireless communication link, which data pertain to at least one access-related service implementable via the access control device. a first communication interface configured to exchange data with a network node, and a second communication interface configured to exchange data wirelessly with mobile communication apparatuses, characterized in that the access control device further comprises: a wireless power transmission interface, an energy storage and a control unit configured to: check if an active mobile power source unit, which is controlled by a mobile communication apparatus via a master link, is located within an operation range of the wireless power transmission interface, and if so establish, via the wireless power transmission interface, a wireless power transfer link with the active mobile power source unit, and subsequently receive energy from the mobile power source unit via the wireless power transfer link, store the received energy in the energy storage, subsequently send a random number to the mobile power source unit using backscatter modulation, which is to be forwarded to the mobile communication apparatus via said master link, and subsequently receive said random number over a wireless communication link via the second communication interface, and based on the verification of said received random number connect logically with the mobile communication apparatus over the wireless communication link, and subsequently exchange data with the mobile communication apparatus over said wireless communication link, which data pertain to at least one access-related service implementable via the access control device. a wireless power transmission interface, an energy storage and a control unit configured to: check if an active mobile power source unit, which is controlled by a mobile communication apparatus via a master link, is located within an operation range of the wireless power transmission interface, and if so establish, via the wireless power transmission interface, a wireless power transfer link with the active mobile power source unit, and subsequently receive energy from the mobile power source unit via the wireless power transfer link, store the received energy in the energy storage, subsequently send a random number to the mobile power source unit using backscatter modulation, which is to be forwarded to the mobile communication apparatus via said master link, and subsequently receive said random number over a wireless communication link via the second communication interface, and based on the verification of said received random number connect logically with the mobile communication apparatus over the wireless communication link, and subsequently exchange data with the mobile communication apparatus over said wireless communication link, which data pertain to at least one access-related service implementable via the access control device. check if an active mobile power source unit, which is controlled by a mobile communication apparatus via a master link, is located within an operation range of the wireless power transmission interface, and if so establish, via the wireless power transmission interface, a wireless power transfer link with the active mobile power source unit, and subsequently receive energy from the mobile power source unit via the wireless power transfer link, store the received energy in the energy storage, subsequently send a random number to the mobile power source unit using backscatter modulation, which is to be forwarded to the mobile communication apparatus via said master link, and subsequently receive said random number over a wireless communication link via the second communication interface, and based on the verification of said received random number connect logically with the mobile communication apparatus over the wireless communication link, and subsequently exchange data with the mobile communication apparatus over said wireless communication link, which data pertain to at least one access-related service implementable via the access control device.