Lau Ka Ming. / Thesis submitted in: August 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 69-72). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.viii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Wireless Ad Hoc Networks --- p.2 / Chapter 1.2.1 --- Wireless Sensor Network --- p.3 / Chapter 1.2.2 --- IEEE802.11 Ad Hoc Network --- p.3 / Chapter 1.2.3 --- Bluetooth Personal Area Network --- p.4 / Chapter 1.3 --- Power Saving in Wireless Ad Hoc Networks --- p.4 / Chapter 1.4 --- Contributions of the Thesis --- p.8 / Chapter 1.5 --- Outline of the Thesis --- p.9 / Chapter 2 --- Power Saving Mechanisms in Wireless Ad hoc Networks --- p.10 / Chapter 2.1 --- Recent Research Proposals --- p.10 / Chapter 2.1.1 --- Synchronous Power Saving Schemes --- p.11 / Chapter 2.1.2 --- Asynchronous Power Saving Schemes --- p.12 / Chapter 2.2 --- Existing Standards --- p.17 / Chapter 2.2.1 --- IEEE802.1l Ad Hoc Power Saving Mode --- p.17 / Chapter 2.2.2 --- Bluetooth Low Power Modes --- p.20 / Chapter 3 --- Analytical Framework for Designing Synchronous Wakeup Patterns --- p.22 / Chapter 3.1 --- System Model --- p.23 / Chapter 3.1.1 --- Vacation Model --- p.23 / Chapter 3.1.2 --- Optimal Wakeup Pattern --- p.25 / Chapter 3.2 --- Analytical analysis of different wakeup patterns --- p.27 / Chapter 3.2.1 --- Exhaustive Wakeup Pattern --- p.27 / Chapter 3.2.2 --- Gated Wakeup Pattern --- p.31 / Chapter 3.2.3 --- Gated Wakeup With Constant Cycle Time --- p.34 / Chapter 3.3 --- Discussion of results --- p.43 / Chapter 3.3.1 --- Performances impacts of various system parameters --- p.43 / Chapter 3.3.2 --- Performances comparison of different wakeup patterns --- p.47 / Chapter 3.4 --- Chapter Summary --- p.48 / Chapter 4 --- An improved IEEE802.1l Power Saving Mode --- p.49 / Chapter 4.1 --- Related Proposals --- p.50 / Chapter 4.2 --- Proposed Scheme --- p.52 / Chapter 4.2.1 --- Overview --- p.52 / Chapter 4.2.2 --- Beacon Sending Station --- p.53 / Chapter 4.2.3 --- Beacon Receiving Station --- p.55 / Chapter 4.2.4 --- Computing the Transmission Schedule --- p.55 / Chapter 4.2.5 --- Data Transmission Specifications --- p.56 / Chapter 4.2.6 --- Failure Conditions --- p.58 / Chapter 4.3 --- Performances Evaluation --- p.58 / Chapter 4.3.1 --- Simulation Model --- p.60 / Chapter 4.3.2 --- Simulation Results --- p.60 / Chapter 4.4 --- Chapter Summary --- p.64 / Chapter 5 --- Conclusion --- p.66

MANETs are known to be useful in situations where mobile nodes need to communicate and coordinate in dynamic environments with no access to fixed network infrastructure. However, connectivity problems can occur when sub-groups within a MANET move out of communication range from one another. The increasingly prolific use of UAVs in military and civilian contexts suggests that UAVs may be very useful for facilitating connectivity between otherwise disconnected mobile nodes. Network Centric Warfare (NCW) theory makes heavy use of MANETs, and UAVs also fit well into the NCW theory; this paper describes the work involved in integrating network enabled UAVs into a previously-developed simulation of ground troop mobility called UMOMM. Specifically, we created a simple decision model for constrained, constant-radius UAV movements, and developed a target-based method by which UAVs can distribute themselves in order to improve the connectivity of the ground members of the MANET. / Graduation date: 2012

Most existent protocols, applications and services for Mobile Ad Hoc NET-works (MANETs) assume a cooperative and friendly network environment and do not accommodate security. Therefore, Intrusion Detection Systems (IDSs), serving as the second line of defense for information systems, are indispensable for MANETs with high security requirements. Central to the research described in this dissertation is the proposed two-level nonoverlapping Zone-Based Intrusion Detection System (ZBIDS) which fit the unique requirement of MANETs. First, in the low-level of ZBIDS, I propose an intrusion detection agent model and present a Markov Chain based anomaly detection algorithm. Local and trusted communication activities such as routing table related features are periodically selected and formatted with minimum errors from raw data. A Markov Chain based normal profile is then constructed to capture the temporal dependency among network activities and accommodate the dynamic nature of raw data. A local detection model aggregating abnormal behaviors is constructed to reflect recent subject activities in order to achieve low false positive ratio and high detection ratio. A set of criteria to tune parameters is developed and the performance trade-off is discussed. Second, I present a nonoverlapping Zone-based framework to manage locally generated alerts from a wider area. An alert data model conformed to the Intrusion Detection Message Exchange Format (IDMEF) is presented to suit the needs of MANETs. Furthermore, an aggregation algorithm utilizing attribute similarity from alert messages is proposed to integrate security related information from a wider area. In this way, the gateway nodes of ZBIDS can reduce false positive ratio, improve detection ratio, and present more diagnostic information about the attack. Third, MANET IDSs need to consider mobility impact and adjust their behavior dynamically. I first demonstrate that nodes?? moving speed, a commonly used parameter in tuning IDS performance, is not an effective metric for the performance measurement of MANET IDSs. A new feature -link change rate -is then proposed as a unified metric for local MANET IDSs to adaptively select normal profiles . Different mobility models are utilized to evaluate the performance of the adaptive mechanisms.

The goal of this thesis work is to analyze how design elements and wireless attributes affect opportunistic routing, and in this context develop a new protocol. The algorithm developed aims to improve opportunistic elements in comparison to a well-known opportunistic protocol Simple Opportunistic Adaptive Routing (SOAR).

During the route discovery process, each node receiving the route request packet (RReq) will retransmit it exactly once. A distant neighbor may accidentally receive/loose the only RReq and use it to announce a new route, although that link is inferior/superior for route reply packets (RRep) or actual message routing. Overall, the constructed route may be far from the optimal. All existing route discovery schemes (including DSR/AODV) apply retransmission during route discovery exactly once (1R). Based on a realistic physical layer model, we propose two new route discovery schemes: n-retransmission (nR, retransmitting exactly n times) and n-retransmission c-reception (ncRR), retransmitting until we either reach a total of n own retransmissions or c copies from neighbors are heard. We compare our two new scheme with the traditional one, under otherwise identical conditions (same metric, same packet reception probability on each link) and the same choices about possibly retransmitting again upon discovering a better route (R+) or discarding it (R1), generating route reply packet for every received RRep (B*), or for first and better discovered routes only (B2), and retransmitting RRep exactly once (A1), up to a maximum of three times (A3), or optimally u times decided by link quality (Au). Experimental results show that the proposed ncRR scheme (for n=2 and c=3 or c=4) achieves the best tradeoff between quality of route, success rate and message overhead in the route discovery process, followed by the nR scheme, and both of them are superior to the existing traditional schemes.

Face routing is a simple method for routing in wireless ad-hoc networks. It only uses location information about nodes to do routing and it provably guarantees message delivery in static connected plane graphs. However, a static connected plane graph is often difficult to obtain in a real wireless network. This thesis extends face routing to more realistic models of wireless ad-hoc networks. We present a new version of face routing that generalizes and simplifies previous face routing protocols and develop techniques to apply face routing directly on general, non-planar network graphs. We also develop techniques for face routing to deal with changes to the graph that occur during routing. Using these techniques, we create a collection of face routing protocols for a series of increasingly more general graph models and prove the correctness of these protocols.

Face routing is a simple method for routing in wireless ad-hoc networks. It only uses location information about nodes to do routing and it provably guarantees message delivery in static connected plane graphs. However, a static connected plane graph is often difficult to obtain in a real wireless network. This thesis extends face routing to more realistic models of wireless ad-hoc networks. We present a new version of face routing that generalizes and simplifies previous face routing protocols and develop techniques to apply face routing directly on general, non-planar network graphs. We also develop techniques for face routing to deal with changes to the graph that occur during routing. Using these techniques, we create a collection of face routing protocols for a series of increasingly more general graph models and prove the correctness of these protocols.

During the route discovery process, each node receiving the route request packet (RReq) will retransmit it exactly once. A distant neighbor may accidentally receive/loose the only RReq and use it to announce a new route, although that link is inferior/superior for route reply packets (RRep) or actual message routing. Overall, the constructed route may be far from the optimal. All existing route discovery schemes (including DSR/AODV) apply retransmission during route discovery exactly once (1R). Based on a realistic physical layer model, we propose two new route discovery schemes: n-retransmission (nR, retransmitting exactly n times) and n-retransmission c-reception (ncRR), retransmitting until we either reach a total of n own retransmissions or c copies from neighbors are heard. We compare our two new scheme with the traditional one, under otherwise identical conditions (same metric, same packet reception probability on each link) and the same choices about possibly retransmitting again upon discovering a better route (R+) or discarding it (R1), generating route reply packet for every received RRep (B*), or for first and better discovered routes only (B2), and retransmitting RRep exactly once (A1), up to a maximum of three times (A3), or optimally u times decided by link quality (Au). Experimental results show that the proposed ncRR scheme (for n=2 and c=3 or c=4) achieves the best tradeoff between quality of route, success rate and message overhead in the route discovery process, followed by the nR scheme, and both of them are superior to the existing traditional schemes.

Multi-channel MAC protocol is that schedules frames to be exchanged on different channels. To analyze the performance of multi-channel MAC protocol, an analytical model is proposed to compute the network throughput. Simulation results show that the proposed model is able to model the behaviors of multi-channel MAC protocol accurately. Furthermore, based on the analysis model, in this thesis we also proposes an adaptive contention window scheme to enhance the network throughput by tuning the initial contention window size. Results indicate that the proposed scheme can reduce the cost of collisions and increase the network throughput.

In this paper we propose a distributed algorithm to construct a scatternet for multi-hop ad hoc networks of Bluetooth devices. This algorithm is fully distributed and does not require the nodes in the networks being in-range(i.e., each pair of nodes in the network may be unable to communicate with each other directly). The role-selection process in existing scatternet formation mostly uses the strategy of message exchange and comparing their weights like IDs or power strength. This results in a large amount of control messages to be sent and a longer scatternet formation time. In our algorithm, the role selection procedure is simple. Nodes can decide their role by a randomly generated counter rather than their ¡¥weights¡¦. According to the proposed approach, nodes can determine their role of either a master or a slave of the piconet without recognizing its neighbors¡¦ ¡¥weight¡¦. The algorithm performs better time and reduces the number of control messages remarkably during the role-selection process. In this paper, we also define the gateways of 2-hops and 3-hops for evaluating the distance between two piconets.