 stream) for small IP packets (e.g., 0 byte payload + IP header) for both downlink and uplink, as hypothetically shown in Figure 1-3. In Figure 1-3, the user-plane latency is measured from point 1 to point 2, or from point 3 to point 4. The following mobility classes are defined in IMT-Advanced systems: Stationary: 0 km/h; Pedestrian: 0 to 10 km/h; Vehicular: 10 to 120 km/h; High speed vehicular: 120 to 350 km/h. A mobility class is supported if the traffic channel link-level data rate, normalized by bandwidth, on the uplink, is as shown in Table 1-2, when the user is moving at the maximum speed in that mobility class in each of the test environments. The handover interruption time is defined as the time duration during which a user terminal cannot exchange user-plane packets with any base station. The handover interruption time includes the time required to execute any radio access network procedure, radio resource signaling protocol, or other message exchanges between the user terminal and the radio access network. For the purposes of determining handover interruption time, interactions with the core network are not considered. It is 1.1 Mobile broadband wireless access technologies also assumed that all necessary attributes of the target base station are known at initiation of the handover from the serving base station. Voice-over-IP (VoIP) capacity is calculated assuming a 12.2 kbps codec with 50% speech activity factor, such that the percentage of users in outage is less than 2% where a user is defined to have experienced a voice outage if less than 98% of the VoIP packets have been delivered successfully to the user within a one way radio access delay bound of 50 msec. The VoIP capacity is the minimum of the calculated capacity for downlink or uplink divided by the effective bandwidth in the respective link direction. For comparison purposes, Table 1-2 further provides the system requirements for the 3GPP LTE- Advanced [20] and the IEEE 802.16m [21] which both have currently targeted certification as IMT- A