Analysis of topology aggregation techniques for QoS routing

We study and compare topology aggregation techniques used in QoS routing. Topology Aggregation (TA) is defined as a set of techniques that abstract or summarize the state information about the network topology to be exchanged, processed, and maintained by network nodes for routing purposes. Due to scalability, aggregation techniques have been an integral part of some routing protocols. However, TA has not been studied extensively except in a rather limited context. With the continuing growth of the Internet, scalability issues of QoS routing have been gaining importance. Therefore, we survey the current TA techniques, provide methodology to classify, evaluate, and compare their complexities and efficiencies. ©2007 ACM.postprin

Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey

Wireless sensor networks (WSNs) consist of autonomous and resource-limited devices. The devices cooperate to monitor one or more physical phenomena within an area of interest. WSNs operate as stochastic systems because of randomness in the monitored environments. For long service time and low maintenance cost, WSNs require adaptive and robust methods to address data exchange, topology formulation, resource and power optimization, sensing coverage and object detection, and security challenges. In these problems, sensor nodes are to make optimized decisions from a set of accessible strategies to achieve design goals. This survey reviews numerous applications of the Markov decision process (MDP) framework, a powerful decision-making tool to develop adaptive algorithms and protocols for WSNs. Furthermore, various solution methods are discussed and compared to serve as a guide for using MDPs in WSNs

Energy-efficient routing protocols in heterogeneous wireless sensor networks

Sensor networks feature low-cost sensor devices with wireless network capability, limited transmit power, resource constraints and limited battery energy. The usage of cheap and tiny wireless sensors will allow very large networks to be deployed at a feasible cost to provide a bridge between information systems and the physical world. Such large-scale deployments will require routing protocols that scale to large network sizes in an energy-efficient way. This thesis addresses the design of such network routing methods. A classification of existing routing protocols and the key factors in their design (i.e., hardware, topology, applications) provides the motivation for the new three-tier architecture for heterogeneous networks built upon a generic software framework (GSF). A range of new routing algorithms have hence been developed with the design goals of scalability and energy-efficient performance of network protocols. They are respectively TinyReg - a routing algorithm based on regular-graph theory, TSEP - topological stable election protocol, and GAAC - an evolutionary algorithm based on genetic algorithms and ant colony algorithms. The design principle of our routing algorithms is that shortening the distance between the cluster-heads and the sink in the network, will minimise energy consumption in order to extend the network lifetime, will achieve energy efficiency. Their performance has been evaluated by simulation in an extensive range of scenarios, and compared to existing algorithms. It is shown that the newly proposed algorithms allow long-term continuous data collection in large networks, offering greater network longevity than existing solutions. These results confirm the validity of the GSF as an architectural approach to the deployment of large wireless sensor networks

Multi-domain crankback operation for IP/MPLS & DWDM networks

Network carriers and operators have built and deployed a very wide range of networking technologies to meet their customers needs. These include ultra scalable fibre-optic backbone networks based upon dense wavelength division multiplexing (DWDM) solutions as well as advanced layer 2/3 IP multiprotocol label switching (MPLS) and Ethernet technologies as well. A range of networking control protocols has also been developed to implement service provisioning and management across these networks. As these infrastructures have been deployed, a range of new challenges have started to emerge. In particular, a major issue is that of provisioning connection services between networks running across different domain boundaries, e.g., administrative geographic, commercial, etc. As a result, many carriers are keenly interested in the design of multi-domain provisioning solutions and algorithms. Nevertheless, to date most such efforts have only looked at pre-configured, i.e., static, inter-domain route computation or more complex solutions based upon hierarchical routing. As such there is significant scope in developing more scalable and simplified multi-domain provisioning solutions. Moreover, it is here that crankback signaling offers much promise. Crankback makes use of active messaging techniques to compute routes in an iterative manner and avoid problematic resource-deficient links. However very few multi-domain crankback schemes have been proposed, leaving much room for further investigation. Along these lines, this thesis proposes crankback signaling solution for multi-domain IP/MPLS and DWDM network operation. The scheme uses a joint intra/inter-domain signaling strategy and is fully-compatible with the standardized resource reservation (RSVP-TE) protocol. Furthermore, the proposed solution also implements and advanced next-hop domain selection strategy to drive the overall crankback process. Finally the whole framework assumes realistic settings in which individual domains have full internal visibility via link-state routing protocols, e.g., open shortest path first traffic engineering (OSPF-TE), but limited \u27next-hop\u27 inter-domain visibility, e.g., as provided by inter-area or inter-autonomous system (AS) routing protocols. The performance of the proposed crankback solution is studied using software-based discrete event simulation. First, a range of multi-domain topologies are built and tested. Next, detailed simulation runs are conducted for a range of scenarios. Overall, the findings show that the proposed crankback solution is very competitive with hierarchical routing, in many cases even outperforming full mesh abstraction. Moreover the scheme maintains acceptable signaling overheads (owing to it dual inter/intra domain crankback design) and also outperforms existing multi-domain crankback algorithms.\u2