METHOD AND APPARATUS FOR SENDING FEEDBACK FOR A DOWNLINK SHARED SERVICE AND ESTIMATING A NUMBER OF WIRELESS TRANSMIT/RECEIVE UNITS

摘要

A method and an apparatus for sending a signal on a contentious feedback channel for a downlink shared service and for estimating a number of wireless transmit/receive units (WTRUs) are disclosed. When a transmission criterion associated with a physical random access feedback channel (P-RAFCH) is satisfied, a physical resource is randomly selected among a plurality of physical resources assigned for the P-RAFCH and a pre- configured signal is sent using the selected physical resource. A Node-B receives the pre-configured signal from a plurality of WTRUs and calculates a number of the WTRUs based on a number of used physical resources. The transmission criterion is at least one of successful reception of a data packet on a downlink physical channel, successful reception of a data block on a data service, reception of a signaling command, occurrence of a measurement event, and failure to receive a transmission after a specified number of times.