(ATM) A.22 Comparing ATM and IP-Based UTRAN The following compares the performance and bandwidth requirement of the ATM and IP based UTRAN. Figure A.41 compares the calculated bandwidth efficiency of the ATM-based and the IP-based UTRAN of without using multiplexing (IP), using Composite IP (CIP) and Lightweight IP Encapsulation (LIPE) multiplexing schemes. The comparison is given for each RAB type. The LIPE and CIP are the proposed multiplexing schemes by 3GPP [3GP04a] for implementing the IP-based UTRAN (see section 2.3.4.1), which are optional. The detailed introduction of the CIP and LIPE schemes are given in Appendix A.11. If not using multiplexing, each radio frame (i.e. FP PDU) is encapsulated into one UDP/IP packet. With CIP and LIPE schemes, it allows multiplexing multiple radio frames (FP PDU) into one UDP/IP packet, and thus reduces the relative UDP/IP transport overheads. It can be seen that for low RAB type such as AMR voice and 64 kbps, the ATM-based UTRAN achieves higher efficiency than the IP-based UTRAN of without using multiplexing scheme. This is because that the radio frame sizes of low RAB types are relatively small, and thus the added UDP/IP/Ethernet overhead of the IP transport network is larger compared to A.22 Comparing ATM and IP-Based UTRAN the ATM transport. On the other hand, the bandwidth efficiency of the IP-based UTRAN increases for higher RAB rate and even exceeds the efficiency of the ATM-based UTRAN when the RAB rates are 128 kbps or above. This is because that with higher RAB rate, the radio frame sizes are larger and thus the overhead of UDP/IP/Ethernet is relatively smaller than the one in the ATM-based UTRAN. When multiplexing scheme is applied in the IP- based UTRAN, with either CIP or LIPE scheme, it can be seen that the bandwidth efficiency is significantly better compared with not using the multiplexing scheme in the IP-based UTRAN, and also better than ATM-based UTRAN. This is because a multiplexing gain is achieved with combining several radio frames into one IP packet