The fourth-generation wireless mobile systems, commonly known as 4G, is expected to provide global roaming across different types of wireless and mobile networks; for instance, from satellite to mobile networks and to Wireless Local Area Networks (WLANs). 4G is an all IP-based mobile network using different radio access technologies and providing seamless roaming and connection via always the best available network (Zahariadis & Kazakos, 2003). The vision of 4G wireless/mobile systems will be the provision of broadband access, seamless global roaming and Internet/data/voice everywhere, utilizing for each the most “appropriate” always-best connected technology (Gustafsson & Jonsson, 2003). These systems are about integrating terminals, networks and applications to satisfy increasing user demands (Ibrahim, 2002; Lu & Berezdivin, 2002). 4G systems are expected to offer a speed of more than 100 Mbps in stationary mode and an average of 20 Mbps for mobile stations, reducing the download time of graphics and multimedia components by more than 10 times compared to currently available 2 Mbps on 3G systems.
