The development of ubiquitous mobile computing devices has fueled the need for dynamic reconfigurable networks. Mobile ad-hoc network (MANET) routing protocols facilitate the creation of such networks, without centralized infrastructure. One of the challenges in the study of MANET routing protocols is the evaluation and design of an effective routing protocol that works at low data rates and responds to dynamic changes in network topology due to node mobility. Several routing protocols have been standardized by the Internet Engineering Task force (IETF) to address ad-hoc routing requirements. The performance of these protocols are investigated in detail in this thesis. A relatively new approach to ad-hoc routing using the concept of a Minimal Connected Dominating Set (MCDS) has been developed at Virginia Tech. The OSPF-MCDS routing protocol is a modified version of the traditional Open Shortest Path First (OSPF) wired routing protocol which incorporates the MCDS framework. Enhancements to the protocol implementation to support multiple-interface routing are presented in this thesis. The protocol implementation was also ported to ns-2, a popular open source network simulator. Several enhancements to the implementation and simulation model are discussed along with simulation specifics. New scenario visualization tools for mobility pattern generation and analysis are described. A generic framework and tutorial for developing new ad-hoc routing simulation models are also presented. The simulation model developed is used to compare the performance characteristics of OSPF-MCDS to three different standardized MANET routing protocols. Simulation results presented here show that no single protocol can achieve optimal performance for all mobility cases. Different observations from simulation experiments are summarized that support the likely candidate for different mobility scenarios. / Master of Science

Wireless mobile ad-hoc networks consist of a collection of peer mobile nodes that form a network and are capable of communicating with each other without help from stationary infrastructure such as access points. The availability of low-cost, com-modity network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC protocol for wireless mobile ad-hoc net-works, even though it is not optimal. The IEEE 802.11 MAC protocol is designed to have stations share a single channel in a given network. However, many of the IEEE 802.11 physical (PHY) layer specifications define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, multiple communications can occur at the same time, offering the opportunity to increase the effective network capacity. We present an innovative routing protocol that utilizes multiple channels to im-prove the performance of wireless ad-hoc networks. The basic idea of the protocol is to use multiple channels so that multiple useful transmissions can occur simultane-ously, thus increasing network capacity. The proposed scheme requires minor changes to existing proactive ad-hoc routing protocols and no modifications to the current IEEE 802.11 MAC protocol. To reduce inefficiencies due to periodic updates in the proactive routing protocols, the proposed scheme divides the network layer into control and data planes. Nodes send routing updates using the control channel and user packets using the data channel. To demonstrate the multi-channel routing scheme, we extend the Destination-Sequenced Distance-Vector (DSDV), Open Shortest Path First-Minimal Connected Dominating Set (OSPF-MCDS), and Optimized Link State Routing (OLSR) protocol to multiple channel (MC) versions, denoted as DSDV-MC, OSPF-MCDS-MC, and OLSR-MC, respectively. Simulation results for DSDV-MC, OSPF-MCDS-MC, and OLSR-MC are presented and experimental results for OLSR-MC are presented. Simulation results indicate that DSDV-MC and OSPF-MCDS-MC effectively exploit multiple channels to improve network capacity. Goodput, the throughput consider-ing only useful error-free packets, increases with an increased number of available channels as the number of nodes and network load increase in both single-hop and multiple-hop networks. Experimental results with OLSR-MC also support that the proposed scheme increases network capacity without modification to the MAC proto-col in a real implementation. Although simulation and experimental results show that proposed scheme im-proves network capacity by exploiting multiple channels, problems exist with channel distribution. We introduce a new metric, the Channel Distribution Index (CDI) to in-vestigate these issues. The CDI indicates the fairness of the channel distribution. We identify the channel convergence problem, where a particular channel is over-utilized, and propose a channel reallocation scheme to mitigate the impact of the channel convergence problem using the CDI. / Ph. D.