verhead compared to relatively smaller FP PDU frame. Bandwidth Efficiency (RAB 64kbps) IP LIPE 5ms Timer IP LIPE 10ms Timer Number of UEs Figure A.44: Simulated bandwidth efficiency - ATM VS. IP-based UTRAN (web traffic) Figure A.45 shows the measured FP PDU delay of different transport layer schemes, as a function of the number of active users. It shows that in this case the IP-based UTRAN with LIPE multiplexing scheme gets a higher FP PDU delays than the ATM-based UTRAN due to a higher multiplexing timer value (ATM-based UTRAN uses 1ms timer at the AAL2 layer) However, IP-based UTRAN without multiplexing achieves a slightly lower FP PDU delay than the one in the ATM-based UTRAN when the load is lower than 30 numbers of UEs. But when the load is increased, the FP PDU delay is increased significantly. This is due to more resource is occupied for transferring the overhead information and no multiplexing gain is achieved in this case. We can also observe that with longer multiplexing timer in the IP-based UTRAN, the bandwidth efficiency is higher, but the FP PDU delay gets worse. Therefore, there is a tradeoff between the packet delay and the efficiency. Appendix FP PDU Delay (RAB 64kbps) IP LIPE 5ms timer IP LIPE 10ms Timer Number of UEs Figure A.45: Simulated FP PDU delay - ATM vs. IP-based UTRAN (web traffic) Based on the above investigations, it is found that there is also a tradeoff between the efficiency and the delay. Therefore, optimization of the multiplexing parameters is important for the dimensioning. Bibliography [3GP99a] 3GPP, Technical Specification Group Services and System Aspects. Mandatory Speech Codec Speech Processing Functions AMR Speech Codec; General Description. 3GPP TS 26.071 version 3.0.1, August 1999. [3GP99b] 3GPP, Technical Specification Group RAN. Radio Interface Protocol Architecture. 3GPP TS 25.301 version 3.3.0, December 1999. [3GP99c] 3GPP, Technical Specification Group RAN. Physical Channels and Mapping of Transport Channels onto Physical Channels (FDD). 3GPP TS 25.211 version 3.