A method for operating a system for controlling access to an access-restricted zone in a building, the system comprising a control device (10, 11), a stationary transmitting device for a first radio signal, a receiving device for radio signals, and a signal processing device communicatively connected to the receiving device, the method comprising: determining, by means of the signal processing device, a first channel impulse response (h 1 (τ)) based on the first radio signal received by the receiving device; and ascertaining from the first channel impulse response (h 1 (τ)) a first sequence of temporally successive first multi-path signal components (SC k), determining, by means of the signal processing device, a second channel impulse response (h 2 (τ)) based on a second radio signal received by the receiving device, the second radio signal being transmitted from a first mobile electronic device of a first user, and ascertaining from the second channel impulse response (h 2 (τ)) a second sequence of temporally successive second multi-path signal components (SC k); determining, by means of the signal processing device, a degree of similarity (SD s, SD A) by means of an evaluation of the first channel impulse response (h 1 (τ)) and the second channel impulse response (h 2 (τ)), the degree of similarity (SD s, SD A) indicating how similar the first channel impulse response (h 1 (τ)) and the second channel impulse response (h 2 (τ)) are, the evaluation of the first and second channel impulse responses (h 1 (τ), h 2 (τ)) involving comparing in pairs, according to the order in the first and second sequence, each second multi-path signal component (SC k) with its first multi-path signal component (SC k) corresponding to the sequence in order to determine, for each pair (P1, P2, P3, P4), a temporal deviation (Δ k) such that a maximum temporal deviation (Δ k) and a minimum time deviation (Δ k) are present, the degree of similarity (SD s, SD A) being based on at least one of these temporal deviations (Δ k); and initiating a building action by means of the controller when a specified rule is met based on the degree of similarity (SD s, SD A), the radio signals (RF1, RF2) having a bandwidth of at least 500 MHz and being transmitted and received according to a WLAN/WiFi Standard or a standard for ultra-broadband technology. determining, by means of the signal processing device, a first channel impulse response (h 1 (τ)) based on the first radio signal received by the receiving device; and ascertaining from the first channel impulse response (h 1 (τ)) a first sequence of temporally successive first multi-path signal components (SC k), determining, by means of the signal processing device, a second channel impulse response (h 2 (τ)) based on a second radio signal received by the receiving device, the second radio signal being transmitted from a first mobile electronic device of a first user, and ascertaining from the second channel impulse response (h 2 (τ)) a second sequence of temporally successive second multi-path signal components (SC k); determining, by means of the signal processing device, a degree of similarity (SD s, SD A) by means of an evaluation of the first channel impulse response (h 1 (τ)) and the second channel impulse response (h 2 (τ)), the degree of similarity (SD s, SD A) indicating how similar the first channel impulse response (h 1 (τ)) and the second channel impulse response (h 2 (τ)) are, the evaluation of the first and second channel impulse responses (h 1 (τ), h 2 (τ)) involving comparing in pairs, according to the order in the first and second sequence, each second multi-path signal component (SC k) with its first multi-path signal component (SC k) corresponding to the sequence in order to determine, for each pair (P1, P2, P3, P4), a temporal deviation (Δ k) such that a maximum temporal deviation (Δ k) and a minimum time deviation (Δ k) are present, the degree of similarity (SD s, SD A) being based on at least one of these temporal deviations (Δ k); and initiating a building action by means of the controller when a specified rule is met based on the degree of similarity (SD s, SD A), the radio signals (RF1, RF2) having a bandwidth of at least 500 MHz and being transmitted and received according to a WLAN/WiFi Standard or a standard for ultra-broadband technology.