insensitive data, for which link efficiency is more important than a low delay value. A.12 Exact IP-Based UTRAN Simulation Model FP PDU FP PDU Header Header LIPE Container Length Extended 7 bits Headers 8 bits (a) Basic Multiplexed Header Length Seq no. FlowID 7 bits 3 bits 12 bits (b) Extended Multiplexed Header with Seq No and FlowID Length Seq no. FlowID 7 bits 3 bits 11 bits (c) Extended Multiplexed Header with Seq No and FlowID Figure A.11: LIPE packet format For each multiplexer, the number of packets to encapsulate in a LIPE or CIP container is determined by its multiplexing timer and the maximum container packet size. Accordingly, for the above three multiplexers, separate buffers are needed. Timers start when the first FP PDU arrives. If the number of encapsulated packets reaches the maximum number of FP PDUs allowed in one container, then the timer stops and the container packet is encapsulated into the UDP payload and then sent out. But if there are not enough packets in the buffer before the timer expires, the packet will be sent out right away even though the container length does not reach the maximum. A.12 Exact IP-Based UTRAN Simulation Model The following gives a detailed description of the modeling of the transport network UDP/IP and Ethernet layers, and the related traffic control and QoS scheme in this exact IP- based UTRAN simulation model, which is briefly introduced in section 5.5.1. Modeling of UDP/IP The UDP and IP layers are implemented below the FP layer. The main function of UDP is manage the transport connection for each user flow and provide a unique identification for the individual user connections. The UDP port numbers in the UDP header field together with the node IP address are utilized to identify different user connections. The UDP layer receives the FP PDUs and encapsulates each FP PDU into one UDP packet by adding 8 bytes UDP header. When a UDP PDU is encapsulated, it is forwarded to the transport IP layer. Appendix In the simulation model, the transport layer IP module impl