A method of determining a relative location of one or more access controls , the method comprising: detecting a first wireless signal from a first access control of the one or more access controls ; determining a unique device identifier for the first access control based on the first wireless signal ; determining a received signal strength indicator of the first wireless signal ; and generating a location fingerprint to associate the received signal strength indicator of the first wireless signal with the unique device identifier for the first access control ; wherein the relative location is a location of each of the one or more access controls relative to each other, and each of the one or more access controls is a door lock or turnstile lock; and the method further comprises: detecting a second wireless signal from a second access control ; determining a unique device identifier for the second access control based on the second wireless signal; determining a received signal strength indicator of the second wireless signal; and updating the location fingerprint to associate the received signal strength indicator of the second wireless signal with the unique device identifier for the second access control ; characterised in that the method further comprises transmitting the location fingerprint to a server , the server being configured to update a location fingerprint array in response to the location fingerprint. detecting a first wireless signal from a first access control of the one or more access controls ; determining a unique device identifier for the first access control based on the first wireless signal ; determining a received signal strength indicator of the first wireless signal ; and generating a location fingerprint to associate the received signal strength indicator of the first wireless signal with the unique device identifier for the first access control ; wherein the relative location is a location of each of the one or more access controls relative to each other, and each of the one or more access controls is a door lock or turnstile lock; and the method further comprises: detecting a second wireless signal from a second access control ; determining a unique device identifier for the second access control based on the second wireless signal; determining a received signal strength indicator of the second wireless signal; and updating the location fingerprint to associate the received signal strength indicator of the second wireless signal with the unique device identifier for the second access control ; characterised in that the method further comprises transmitting the location fingerprint to a server , the server being configured to update a location fingerprint array in response to the location fingerprint. detecting a second wireless signal from a second access control ; determining a unique device identifier for the second access control based on the second wireless signal; determining a received signal strength indicator of the second wireless signal; and updating the location fingerprint to associate the received signal strength indicator of the second wireless signal with the unique device identifier for the second access control ; characterised in that the method further comprises transmitting the location fingerprint to a server , the server being configured to update a location fingerprint array in response to the location fingerprint. <EOS>