In a wireless network comprising access points deployed within a designated zone of coverage, the radio frequency field strength resulting from radiation from the access points is optimised as a function of location by means of control of the transmission power and/or radiation pattern of the access points in response to measurements from sensors at defined locations that measure received signal power, the received power being related to radio frequency field strength. Sensors may be deployed within the designated zone of coverage, at the edge of the zone and/or outside the zone and optimization of the transmission parameters of the access points in terms of transmission power and/or radiation pattern is carried out taking into account the location of the sensors in addition to the received power at the sensors.