The substitution of ATM transport by IP in future UMTS Radio Access Networks (UTRAN) introduces several performance challenges that need to be addressed to guarantee the feasibility of its deployment. The significant increase of the overhead requires of header compression and multiplexing methods to achieve a usage of the UTRAN resources similar to the ATM one. Additionally, the specific UTRAN transport needs require the adaptation of standard packet scheduling mechanisms to efficiently use the network resources while providing the required QoS. Our results show that, applying header compression plus multiplexing techniques and taking into account the specific UTRAN synchronization requirements for QoS scheduling, very significant performance improvements can be obtained. Categories and Subject Descriptors C.2.1 [Computer-Communication Networks]: Network Architecture and Design-Wireless Communications; C.4 [Computer Systems Organization]: Performance of Systems General Terms Desi...