Patent ID: 8102788

Claim:
A method of supporting a serving cell change from a source Node-B to a target Node-B implemented in a wireless transmit/receive unit (WTRU), the method comprising: receiving from the source Node-B a plurality of resource allocations associated with a first serving cell; transmitting, in response to the receipt of the plurality of resource allocations from the source Node-B, a first sequence of protocol data units (PDUs) to at least the source Node-B, wherein each PDU is assigned a respective sequence number; receiving a radio resource control (RRC) message indicating a serving cell change from the source Node-B to the target Node-B, wherein the source Node-B is a single Node-B and the target Node-B is a single Node-B, wherein the serving cell change is an enhanced uplink dedicated channel (EU-DCH) inter-Node-B serving cell change; receiving from the target Node-B a plurality of resource allocations associated with a second serving cell in response to the received RRC message; setting an indicator for transmitted PDUs that have not been acknowledged by the source Node-B; transmitting, in response to the receipt of the plurality of resource allocations from the target Node-B, a second sequence of PDUs to at least the target Node-B, wherein each PDU corresponds to a PDU in the first sequence indicated as not being acknowledged by the source Node-B, and each PDU maintains the same sequence number assigned to the corresponding PDU in the first sequence; and transmitting a message indicating completion of the EU-DCH inter-Node-B serving cell change.