1. A method performed in a wireless transmit/receive unit (WTRU), the method comprising: determining a measured number of cell reselections; and setting a mobility state based on the measured number of cell reselections; wherein the mobility state is set to a low mobility state when the measured number of cell reselections is less than a first threshold, the mobility state is set to a medium mobility state when the measured number of cell reselections is more than the first threshold but less than a second threshold, and the mobility state is set to a high mobility state when the measured number of cell reselections is more than the second threshold.