A new protocol data unit is used in communications in a radio access network. When a user equipment requests a radio resource controller connection, the UE includes its identity in the request message. In establishing the connection to UE, a serving radio network controller allocates a logical channel to the UE for communications and identifies the logical channel in the header of the protocol data unit so as to allow a receiver of the PDU to know the UE identity in an out-of-band signaling fashion, depending upon a state of the transmitter of the PDU. When the transmitter changes its state, the receiver can change state accordingly. The new PDU structure allows continuous reception of the HS-DSCH downlink channel during state transition form CELL_FACH or CELL_PCH or URA_PCH to CELL_DCH and vice versa. This new PDU structure also allows continuous HS_DSCH retransmissions.