Mobile Broadband (MBB) traffic is increasing rapidly, and is estimated to keep growing in future due to the availability of high speed 3G/4G networks and the popularity of mobile devices. People are accessing Internet irrespective of their locations and time thus introducing mobility in the access paradigm and making MBB as a future of the Internet. The expansion of MBB traffic necessitates the detail study of the characteristics of MBB networks with regards to network performance and reliability. It is observed that the literature towards the study of MBB performance mostly concern static scenarios. Therefore, in this thesis, effects of mobility on MBB performance are studied, and the QoS performance of Norwegian MBB networks under mobility are compared to provide a realistic view of the QoS characteristics experienced by the end-users. For this, performance metrics such as delay, packet loss, connectivity are measured for four operational MBB networks under mobility simultaneously using NorNet Edge (NNE), the dedicated testbed for experimentation and measurements in MBB networks. Measurements in different speed are examined to see how speed affects MBB performance. Radio conditions such as Local Area Code (LAC), Cell Identification (CellID) are also investigated to establish relation between the measured performance and physical locations as well as cell attachment and handover behaviors. Mode and Submode are also observed to see 2G/3G networks coverage and packet distribution in HSPA+, HSDPA, HSUPA, WCDMA and EDGE networks. The results of this thesis show that MBB performance is affected (degraded) by mobility, but degree varies with respect to performance metrics. It was found that MBB operators under mobility perform differently even though the underlying technology is same.