ABSTRACT
Contents 6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 6.2 Basic Radio Resource Management (RRM) and Challenges . . . . . . . 173 6.3 Case Study: Optimal Call Admission Control Policy
in Heterogeneous Wireless Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 6.3.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 6.3.2 Handoffs in Heterogeneous Wireless Networks . . . . . . . . . . . . 176 6.3.3 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 6.3.4 Contributions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 6.3.5 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 6.3.6 Markov Decision Process Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
6.3.6.1 State Space. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 6.3.6.2 Action Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 6.3.6.3 Sojourn Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 6.3.6.4 Transition Probability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 6.3.6.5 Reward Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6.3.7 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
6.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
6.1 Overview Future wireless and mobile networks will rely on more than one type of radio access technology, including cellular networks, wireless local area networks (WLANs), and multi-hop/ad hoc variable topology networks. Seamless intersystem mobility across heterogeneous networks will be one of the main features in future-generation wireless networks. This change in the technological landscape further challenges today’s radio systems by the increasing amount of capacity-demanding services. The services span from traditional conversational audio to conversational video, voice messaging, streamed audio and voice, fax, telnet, interactive games, Web browsing, file transfer, paging, and e-mailing. No single radio system can effectively cover all these services from a multi-service point of view if Quality-of-Service (QoS) requirements are to be met. Consequently, the development moves toward interworking the different but complementary radio systems that together can provide an unparalleled level of service delivery. Specifically, future wireless networks, called fourth-generation (4G) wireless, will be able to offer personalized service delivery over the most efficient/preferred network, depending on the user profile and the type of data to transmit. 4G wireless networks will be generally characterized by heterogeneity in architectures, protocols, and air interfaces. Interoperability between heterogeneous systems will be provided through different inter-technology coupling techniques and terminal support to several radio interfaces. However, the notion of seamless mobility in heterogeneous wireless networks raises some challenges from the point of view of radio resource management (RRM) and QoS provisioning; for example:
How does one manage resources and control end-to-end QoS for mobile users accessing different services over heterogeneous networks, given that each network possesses its own resource management schemes and policies?
