Meta-Routing: Synergistic Merging of Message Routing and Link Maintenance

The maintenance of network connectivity is essential for effective and efficient mobile team operations. Achieving robust mobile ad hoc networks (MANETs) connectivity requires a capable link maintenance mechanism especially if the network experiences expected intermittent connectivity due to a hostile environment. One applicable example of such network scenarios is multi-robot exploration for urban search and rescue (USAR). With the proliferation of these robotic networks, communication problems such as the link maintenance problem are subject to be raised quickly. Although various routing protocols for wireless ad hoc networks have been proposed, they solve the problems of message routing and link maintenance separately, resulting in additional overhead costs and long latency in network communication. Traditional routing protocols discover existing links, connect these links, find the best path and minimize the path cost. The limitation of previous routing protocols motivates us to develop a new concept of routing mechanism for a robotic network. This routing mechanism is named Meta-Routing. Meta-Routing expands current routing protocols to include not only the normal routing of packets, but also the maintenance of links in mobile agent scenarios. Thus, Meta-Routing minimizes the communication path cost and the overhead cost, the latter of which results from discovering a route, repairing a link or establishing a new communication path between nodes. This dissertation presents a method to achieve Meta-Routing by controlling robot motion based on the radio frequency (RF) environment recognition method and gradient descent method. Mobile robot controlled motion can effectively improve network performance by driving robots to favorable locations with strong links. Moreover, the gradient descent method is used in driving the robots into the direction of favorable positions for maximizing broken or failing links and maintaining network connectivity. The main accomplished goals of this thesis are summarized as follows: firstly, the Meta-Routing protocol, which integrates link maintenance into the normal message routing protocol cost function; secondly, the dissertation examines the unification of the syntax of message routing protocol and the link maintenance process through physical configuration of mobile network nodes by controlling their movement in the field; finally, the dissertation demonstrates that the utilization of the RF environment recognition and classification method improves route repair estimation for achieving link maintenance in the presented Meta-Routing protocol. The numerical experimental results demonstrate promising RF environment recognition and node controlled motion results, as well as confirm their abilities in robot movement control for link maintenance and reduction of the total path cost

Mobility models towards the performance of geographical-based route maintenance strategy in DSR

In the future, Mobile Ad hoc Networks (MANET)s are expected to be deployed in myriads of scenarios having complex node mobility and connectivity dynamics. Unfortunately, these complex movement scenarios give a tough challenge to the MANET routing protocol. We reviewed some mobility models that have different mobility characteristic, and also studied the effect of these mobility models towards the performance of geographical-based route maintenance strategy in the Dynamic Source Routing (DSR) protocol

Robotic Wireless Sensor Networks

In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future

Automatic Optimisation of Reliable Collaborative Services in OLSR Mobile Ad Hoc Networks

International audienceFuture Network based Operations (NbO) will strongly rely on Mobile Ad hoc Networks (MANET), due to urban area, tactical mobility and assymetric operation management. These networks will support multiple collaborative services, such as sensor to shooters, reachback, maintenance of Common Operational Picture (COP). Both networks and services will have to be managed with no or limited operator intervention, still providing reliable behavior in spite of aggressive environments. At routing level, we present how to preserve 2-connectivity by adapting the Optimised Link State Routing Protocol (OLSR). We also introduce the concept of active subnet management to retrieve maximal operational gain from collaborative services. Following a constraint solving method, the paper shows how to maximise the subnet of actors, while satisfying 2-connectivity, reactivity and communication quality constraints. We demonstrate the approach on simulating real world NbO

A Message Passing Strategy for Decentralized Connectivity Maintenance in Agent Removal

In a multi-agent system, agents coordinate to achieve global tasks through local communications. Coordination usually requires sufficient information flow, which is usually depicted by the connectivity of the communication network. In a networked system, removal of some agents may cause a disconnection. In order to maintain connectivity in agent removal, one can design a robust network topology that tolerates a finite number of agent losses, and/or develop a control strategy that recovers connectivity. This paper proposes a decentralized control scheme based on a sequence of replacements, each of which occurs between an agent and one of its immediate neighbors. The replacements always end with an agent, whose relocation does not cause a disconnection. We show that such an agent can be reached by a local rule utilizing only some local information available in agents' immediate neighborhoods. As such, the proposed message passing strategy guarantees the connectivity maintenance in arbitrary agent removal. Furthermore, we significantly improve the optimality of the proposed scheme by incorporating $\delta$-criticality (i.e. the criticality of an agent in its $\delta$-neighborhood).Comment: 9 pages, 9 figure

Experimental Assessment of Cellular Mobile Performance along the Railway Corridor

With the ongoing rehabilitation of the railway transportation sector in Nigeria, improvement in the quality and reliability of the services deliverable becomes crucial. Reliable railway communication infrastructure guarantees effective operation and also ensures connectivity for security, safety, maintenance and passenger communication. This work describes today’s network scenario by assessing current cellular performance as it affects a passenger’s experience along the railway corridor. A drive test was conducted on the 6th of July, 2014 between 12:58pm and 07:14pm along the railroad linking Oshogbo and Lagos, Nigeria. The measurement setup consists of four TEMS Mobile Sony Ericsson W995 phones, a Personal Computer, a GPS receiver, and a power bank. The measurement was useful in the assessment of coverage, capacity and Quality of Service (QoS) of four mobile radio networks namely: Airtel, Globacom, Etisalat and MTN in the GSM 900 MHz and 1800 bands. Results reveal that no single mobile network service operator consistently serviced the train throughout the 6-hour trip. Also, the results obtained from the drive test represents a true picture of mobile network condition and can be useful in decision making in several areas - from planning and design through optimization and maintenance of the system, with the goal of maximizing quality, capacity and coverage for all mobile networks for improved service delivery on our railway infrastructure. Keywords: Railway communication; GSM; Performance of Cellular mobil