UE. "Priorities are e.g. given by attrib- utes of Radio Bearer services and RLC buffer status. The priority handling is achieved by selecting a Transport Format Combination for which high priority data is mapped onto L1 with a 'high bit rate' Transport Format, at the same time letting lower priority data be mapped with a 'low bit rate' (could be zero bit rate) Trans- port Format. Transport format selection may also take into account transmit power indication from Layer 1" [9]. The UMTS Network and Radio Access Technology Priority handling between UEs by means of dynamic scheduling aiming for a dynamic scheduling for efficient spectrum utilization ¹0. The MAC realizes priority handling on common and shared transport channels. Identification of UEs on common transport channels. When addressing a particular UE on a common downlink channel, or when a UE uses the RACH, we need in- band identification of the UE. Multiplexing/de-multiplexing of higher layer PDUs into/from transport blocks de- livered to/from the physical layer on common transport channels. The MAC sup- ports multiplexing for common transport channels as complement to the physical layer. Multiplexing/demultiplexing of higher layer PDUs into/from transport block sets delivered to/from the physical layer on dedicated transport channels. The MAC al- lows service multiplexing for dedicated transport channels. Traffic volume monitoring. Based on the MAC's measurement of traffic volume on logical channels and reported to RRC, the latter performs transport channel switch- ing decisions. Dynamic Transport Channel type switching switching execution between com- mon and dedicated transport channels takes place based on a switching decision de- rived by the RRC. Ciphering. This function prevents unauthorized acquisition of data. Ciphering OC- curs in the MAC layer for transparent RLC mode. Access Service Class selection for RACH transmission. The RACH resources (i.e. access slots and preamble signatures for FDD, timeslot and channelization code for TDD) may be divi