INTEGRATED ARCHITECTURE AND ROUTING PROTOCOLS FOR HETEROGENEOUS WIRELESS NETWORKS
Dave A Cavalcanti · OhioLink ETD Center (Ohio Library and Information Network) · 2006
One of the main challenges in next generation wireless networks is to integrate heterogeneous wireless technologies to provide seamless connectivity, with guaranteed Quality of Service (QoS), to mobile users "anytime, anywhere and with any device".In this dissertation, we investigate the problem of integrating cellular networks and Wireless Local Area Networks (WLANs) with the multi-hop communication paradigm used in Mobile Ad hoc Networks (MANETs) to exploit all the connectivity alternatives available to different types of Mobile Stations (MSs).We propose an integrated architecture based on three basic functionalities, namely, topology discovery, gateway discovery, and link quality estimation.We combine these three functionalities into an integrated routing mechanism that exploits all connectivity alternatives available in a generic heterogeneous scenario.Then, we provide a simulation-based analysis of our architecture and integrated routing mechanism in different heterogeneous networking scenarios.Our results show improvements in network's capacity and coverage achieved by our architecture as compared to isolated networks.The results also highlight the importance of the link quality estimation in providing QoS to users, as well as indicate that multi-hop links can be exploited in a controlled network configuration, but the QoS in multi-hop routes cannot be always guaranteed.Furthermore, we address the problem of selecting the best connectivity opportunity for a given service type based on the applications' QoS requirements, as well as on the network condition and user mobility profile.We propose the Connectivity opportunity Selection Algorithm (CSA) that allows MSs to select the connectivity opportunity most appropriate for a given type of service and mobility profile.Furthermore, we describe how our proposed selection algorithm can be introduced into the IEEE 802.21 standard for Media Independent Handover services. MotivationFrom the rate at which the technology is advancing, it is easier to predict that future networking environments will certainly be heterogeneous in terms of networks, devices and applications.The availability of a multitude of wireless technologies, such as Wireless WANs (e.g., [6], the IEEE 802.16 WMANs [8], and the IEEE 802.11a/b/e/g [9][10] and HiperLAN/2 [11] WLANs.A second step is to integrate these single-hop networks with the revolutionary paradigm of mobile ad hoc networks (MANET), which allows MSs to communicate in a peer-to-peer fashion without any fixed infrastructure.In a MANET, each wireless device acts as router and by using a multi-hop routing protocol; the devices collaborate with each other to forward data packets to the destination.The multi-hop communication paradigm used in MANETs enables communication without the support from fixed infrastructure BSs and APs, providing alternative connections opportunities inside hot-spot cells and extending the systems coverage beyond BS/AP communication ranges.The wireless technologies that support the MANET paradigm include the Scope and MethodologyIntegrated routing in HWNs involves problems in the fixed infrastructure inter-connecting different networks and the Internet, as well as in the wireless environment, which provides the "last mile" access to the users.In this work we focus on the routing issues in the wireless environment and do not consider the issues related to fixed infrastructure, such as the design of fixed interfaces 1 Throughout this work, the term out-of-coverage refers to MSs that cannot directly connect to a BS or AP.heterogeneous environment and identify the main design factors affecting the integrated routing problem.Then, we use a cross-layer design approach to design an integrated architecture and routing protocols that can obtain information from other layers and efficiently select the best endto-end route for a given connection.Our integrated architecture is based on three basic functionalities, namely, topology discovery, gateway discovery, and link quality estimation.Topology discovery is the process by which the network obtains information about the available communication links for the users, while gateway discovery is required to provide connectivity to users that are out-of-coverage of infrastructure network components through multi-hop communication with Gateway Nodes.Link quality estimation is a complementary requirement for both the topology and the gateway discovery, as it provides important information about the capacity of the wireless links.Lastly, but not least, we introduce the concept of connectivity opportunity, which is more than a simple access network, but instead, it is a combination of network type, operation mode, routing and network condition information that can are used by a Chapter 1