er in 3G networks. Typical 2G networks can support 10 kbps per time slot for the basic types of modulation. 2.5G networks are expected to support 80-100 kbps per time slot. WCDMA 3G networks have been specified with bearers of 384 kbps in the downlink, and performances of 330 kbps have been achieved in commercial networks. END-TO-END SYSTEM PERFORMANCE MEASUREMENT Latency One of the most frequent uses of a mobile packet network seems to be Internet surfing. This application typically sends out short packets to the network and then gets a bigger amount of data back from the network. Latency is the measure of how fast the system can transport the small amounts of data from the mobile to a specified server. Latency in typically measured by 'pings'. A ping is a short message to a server by which the 'round trip time' can be measured. A typical round-trip time in 2G networks is 700 ms, and about 500 ms for 32-byte pings to servers located within the mobile network. Video Call Quality Currently there is no standard test available for testing the quality of a multimedia call, whether it be a still picture (MMS - multimedia messaging service) or a video call. Since all video codecs use some kind of compression, a standard is needed to evaluate the quality of a video call. It should be possible to generate the equivalent of the MOS for a video call, which would have humans evaluating the quality of the call. D.4 DRIVE TEST EQUIPMENT Drive test equipment consists of a test mobile connected to a laptop computer, which has some kind of geographic, or location indication instrument attached to it. By default this is usually the global positioning system (GPS). The accuracy of commercial instruments based on this is usually of the order of 5 metres. The GPS system depends on the visibility of satellites to the receiving antenna. This can be difficult in heavily built-up areas (called urban canyons') and in places with a lot of trees. Also road tunnels, underpasses, bridges, etc., can cause such instruments to lose positioning 