Abstract
Today, we find a large number of wireless networks based on different radio access technologies (RATs). Every existing RAT has its own merits. Now the focus is turned towards the next-generation communication networks (Akyildiz, Mohanty, & Xie, 2005), which will seamlessly integrate various existing wireless communication networks, such as wireless local area networks (WLANs, e.g., IEEE 802.11 a/b/g and HIPERLAN/2), wireless wide area networks (WWANs, e.g., 1G, 2G, 3G, IEEE 802.20), wireless personal area networks (WPANs, e.g., Bluetooth, IEEE 802.15.1/3/4), and wireless metropolitan area networks (WMANs, e.g., IEEE 802.16) to form a converged heterogeneous architecture (Cavalcanti, Agrawal, Cordeiro, Xie, & Kumar, 2005). Seamless integration does not mean that the RATs are converged into a single network. Instead the services offered by the existing RATs are integrated as shown in Figure 1. Convergence technology is a technology that combines different existing access technologies such as cellular, cordless, WLAN-type systems, short-range wireless connectivity, and wired systems on a common platform to complement each other in an optimum way and to provide a multiplicity of possibilities for current and future services and applications to users in a single terminal. After creating a converged heterogeneous architecture, the next step is to perform a common radio resource management (RRM) (Magnusson, Lundsjo, Sachs, & Wallentin, 2004). RRM helps to maximize the use of available spectrum resources, support mixed traffic types with different QoS requirements, increase trunking capacity and grade of service (GoS), improve spectrum usage by selecting the best RAT based on radio conditions (e.g., path loss), minimize inter-system handover latency, preserve QoS across multiple RATs, and reduce signaling delay.