The usage of W-LAN increases rapidly today, and may be seen as a 
            threat to GPRS and 3G. However a combination af all technologies seems 
            to be a good solution, and is sometimes referred to as 4G. 
        
This thesis investigates the mobility management in 4G. This includes 
            moblility within a W-LAN hotspot based on IEEE 802.11b, mobility between 
            hotspot-subnets, mobility between different hotspots and mobility 
            between different network technologies such as W-LAN, GPRS and UMTS. 
          
The protocols Dynamics HUT Mobile IP, Cellular IP and Mobile IP are 
            proposed to solve the mobility management and this thesis investigates 
            and compares them from different aspects. Both Dynamics HUT Mobile 
            IP and Cellular IP show a much better performance than Mobile IP, 
            but the performance between them is similar. 
          
An alternative solution called Columbitech Wireless VPN based on 
            session mobility is investigated and compared to Mobile IP based solutions. 
            Columbitech Wireless VPN seems to adapt to different networks in a 
            more convenient way compared to Mobile IP based solutions.