A method and apparatus for measuring a channel quality in wireless transmit/receive units (WTRUs) which are equipped with a subscriber based smart antenna. The WTRUs are equipped with a smart antenna so that the WTRU generates a plurality of directional beams and, optionally, an omni-directional beam. A dwell time is provided in a measurement period to switch a beam from an active beam to a non-active beam. The active beam is one of the plurality of directional beams or, optionally, the omni-directional beam, for communication with one or more serving base station(s). A beam is switched to a non-active beam at the initiation of the dwell time. Signals are received through the switched non-active beam, and samples of the received signals are generated. The samples are stored in a memory. Channel quality is measured using the samples, whereby the dwell time to measure the channel quality is minimized.