User State Recognition in a Wireless Communication System

User state recognition is provided in a wireless communication system comprising a user equipment having a microphone, using the microphone to receive audio signals, dividing the received audio signals into segments, and calculating an audio signal level indicator for each segment. Dependent on a value of at least one audio signal level indicator being less than a predefined threshold, a user state is set to a first state. For example, the first user state may indicate that the user equipment is indoors (e.g. in an office). This may, for example, enable more efficient use of mobile devices in wireless communication systems by means of more accurate estimation of indoor and outdoor user states.The invention is based on indoor and outdoor audio signal recognition algorithms implementing a "silence search" or quiet search, i.e. a search for short time periods when relatively low audio signal level is observed. If these periods are found, the decision that the user is indoors may be made. Otherwise it may be decided that the user is outdoors.