Technologies are generally described for detecting proximity of a client device to a base station in a wireless communication system. Example base station may include a proximity detector and an operation mode controller. The proximity detector may analyze a property of a signal transmitted by a client device to detect an envelope of the signal including a buzz-type waveform. If the envelope of the signal is determined to include a buzz-type waveform, the client device is determined to be within communication range of the base station. Further, the operation mode controller may convert a current operation mode of the base station to a particular operation mode that enables the base station to support communication by the client device. In some embodiments, the buzz-type waveform may be a waveform of an uplink control signal that is transmitted by the client device when it is not actively engaged in communication.