Adoption of vehicular ad hoc networking protocols by networked robots

This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed specifically with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan

A quantitative comparison of ad hoc routing protocols with and without channel adaptation

To efficiently support tetherless applications in ad hoc wireless mobile computing networks, a judicious ad hoc routing protocol is needed. Much research has been done on designing ad hoc routing protocols and some well-known protocols are also being implemented in practical situations. However, one major imperfection in existing protocols is that the time-varying nature of the wireless channels among the mobile terminals is ignored, let alone exploited. This could be a severe design drawback because the varying channel quality can lead to very poor overall route quality in turn, resulting in low data throughput. Indeed, better performance could be achieved if a routing protocol dynamically changes the routes according to the channel conditions. In this paper, we first propose two channel adaptive routing protocols which work by using an adaptive channel coding and modulation scheme that allows a mobile terminal to dynamically adjust the data throughput via changing the amount of error protection incorporated. We then present a qualitative and quantitative comparison of the two classes of ad hoc routing protocols. Extensive simulation results indicate that channel adaptive ad hoc routing protocols are more efficient in that shorter delays and higher rates are achieved, at the expense of a higher overhead in route set-up and maintenance. © 2005 IEEE.published_or_final_versio

Advances in Vehicular Ad-hoc Networks (VANETs): challenges and road-map for future development

Recent advances in wireless communication technologies and auto-mobile industry have triggered a significant research interest in the field of vehicular ad-hoc networks (VANETs) over the past few years. A vehicular network consists of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications supported by wireless access technologies such as IEEE 802.11p. This innovation in wireless communication has been envisaged to improve road safety and motor traffic efficiency in near future through the development of intelligent transportation system (ITS). Hence, governments, auto-mobile industries and academia are heavily partnering through several ongoing research projects to establish standards for VANETs. The typical set of VANET application areas, such as vehicle collision warning and traffic information dissemination have made VANET an interesting field of mobile wireless communication. This paper provides an overview on current research state, challenges, potentials of VANETs as well as the ways forward to achieving the long awaited ITS

Swarm Communication in Space - Evaluating Ad-Hoc Routing Protocols for In-Situ Space Exploration Networks

Upcoming space exploration missions targeted on visiting extraterrestrial worlds like the surface of other planets and moons in our solar system demand new technologies due to more complex mission designs. The utilization of multiple robotic units during such missions enables the investigation of a broad surface area. By establishing communication channels between all the robotic units, a swarm of agents is created capable of jointly executing scientific tasks. These will include the collection of sensor data which is distributed within the swarm agents and sensor measurements, time synchronization, and localization information will be exchanged between the agents. The German Aerospace Center (DLR) has designed a wireless communication system that is suitable for space exploration missions of this type where autonomous robots jointly explore unknown terrain on extraterrestrial worlds. The system enables data transmission as well as localization of the swarm agents by implementing a Physical Layer (PHY) and Medium Access Control (MAC) for unit-to-unit communication in the context of an ad-hoc network during in-situ space exploration missions. To allow the communication of swarm agents which are not in direct communication range, routing protocols are needed to relay packets of other agents. This work presents a network simulation environment focused on in-situ space exploration missions for the evaluation of existing ad-hoc routing protocols. The simulation utilizes a wireless MAC using a Time Division Multiple Access (TDMA) channel access function implemented in this work resembling the DLR MAC on the network’s nodes. Elevation data of the Moon’s surface is taken into account for radio-propagation modeling in the simulation. Within this simulation environment 11 different experiment designs are implemented to evaluate the performance differences of the Dynamic MANET On-demand (DYMO), Destination-Sequenced Distance-Vector (DSDV), and Greedy Perimeter Stateless Routing (GPSR) protocols in operation on the TDMA MAC and a standard IEEE 802.11g MAC. Performance metrics are defined to compare the routing protocols utilizing the different MACs. The evaluation reveals observations like less stable operation of all routing protocols on the TDMA MAC and a bias introduced to the route establishment of the protocols by the builtin ordering. Further, the differences observed in operation of the individual routing protocols is discussed in details, such as DSDV always being capable of establishing the shortest route to its destination whereas the other routing protocols chose longer routes. Especially DYMO preferred staying on longer routes if the shortest route was not initially available. It is concluded that the DLR MAC will benefit from applications and routing protocols being aware of the TDMA scheme and incorporating the TDMA cycles into their operation to avoid additional waiting times or biases

Routing protocols for next generation mobile wireless sensor networks

The recent research interest in wireless sensor networks has caused the development of many new applications and subsequently, these emerging applications have ever increasing requirements. One such requirement is that of mobility, which has inspired an entirely new array of applications in the form of mobile wireless sensor networks (MWSNs). In terms of communications, MWSNs present a challenging environment due to the high rate at which the topology may be changing. As such, the motivation of this work is to investigate potential communications solutions, in order to satisfy the performance demands of new and future MWSN applications. As such this work begins by characterising and evaluating the requirement of a large variety of these emerging applications. This thesis focuses on the area of routing, which is concerned with the reliable and timely delivery of data from multiple, mobile sensor nodes to a data sink. For this purpose the technique of gradient routing was identified as a suitable solution, since data can quickly be passed down a known gradient that is anchored at the sink. However, in a mobile network, keeping the gradient up-to-date is a key issue. This work proposes the novel use of a global time division multiple access (GTDMA) MAC as a solution to this problem, which mitigates the need for regularly flooding the network. Additionally, the concept of blind forwarding is utilised for its low overhead and high reliability through its inherent route diversity. The key contribution of this thesis is in three novel routing protocols, which use the aforementioned principles. The first protocol, PHASeR, uses a hop-count metric and encapsulates data from multiple nodes in its packets. The hop-count metric was chosen because it is simple and requires no additional hardware. The inclusion of encapsulation is intended to enable the protocol to cope with network congestion. The second protocol, LASeR, utilises location awareness to maintain a gradient and performs no encapsulation. Since many applications require location awareness, the communications systems may also take advantage of this readily available information and it can be used as a gradient metric. This protocol uses no encapsulation in order to reduce delay times. The third protocol, RASeR, uses the hop-count metric as a gradient and also does not perform encapsulation. The reduced delay time and the relaxed requirement for any existing method of location awareness makes this the most widely applicable of the three protocols. In addition to analytical expressions being derived, all three protocols are thoroughly tested through simulation. Results show the protocols to improve on the state-of-the-art and yield excellent performance over varying speeds, node numbers and data generation rates. LASeR shows the lowest overhead and delay, which comes from the advantage of having available location information. Alternatively, at the expense of increased overhead, RASeR gives comparatively high performance metrics without the need for location information. Overall, RASeR can be suitably deployed in the widest range of applications, which is taken further by including four additional modes of operation. These include a supersede mode for applications in which the timely delivery of the most recent data is prioritised. A reverse flooding mechanism, to enable the sink to broadcast control messages to the sensor nodes. An energy saving mode, which uses sleep cycles to reduce the networks power consumption, and finally a pseudo acknowledgement scheme to increase the reliability of the protocol. These additions enable RASeR to satisfy the needs of some of the most demanding MWSN applications. In order to assess the practicality of implementation, RASeR was also evaluated using a small testbed of mobile nodes. The successful results display the protocols feasibility to be implemented on commercially available hardware and its potential to be deployed in the real world. Furthermore, a key issue in the real world deployment of networks, is security and for this reason a fourth routing protocol was designed called RASeR-S. RASeR-S is based on RASeR, but introduces the use of encryption and suggests a security framework that should be followed in order to significantly reduce the possibility of a security threat. Whilst the main focus of this work is routing, alternative MAC layers are assessed for LASeR. Unlike the other two protocols, LASeR uses available location information to determine its gradient and as such, it is not reliant on the GTDMA MAC. For this reason several MAC layers are tested and the novel idea of dedicated sensing slots is introduced, as well as a network division multiple access scheme. The selected and proposed MACs are simulated and the GTDMA and two proposed protocols are shown to give the best results in certain scenarios. This work demonstrates the high levels of performance that can be achieved using gradient orientated routing in a mobile network. It has also shown that the use of a GTDMA MAC is an efficient solution to the gradient maintenance problem. The high impact of this work comes from the versatility and reliability of the presented routing protocols, which means they are able to meet the requirements of a large number of MWSN applications. Additionally, given the importance of security, RASeR-S has been designed to provide a secure and adaptable routing solution for vulnerable or sensitive applications

Modeling and simulation of routing protocol for ad hoc networks combining queuing network analysis and ANT colony algorithms

The field of Mobile Ad hoc Networks (MANETs) has gained an important part of the interest of researchers and become very popular in last few years. MANETs can operate without fixed infrastructure and can survive rapid changes in the network topology. They can be studied formally as graphs in which the set of edges varies in time. The main method for evaluating the performance of MANETs is simulation. Our thesis presents a new adaptive and dynamic routing algorithm for MANETs inspired by the Ant Colony Optimization (ACO) algorithms in combination with network delay analysis. Ant colony optimization algorithms have all been inspired by a specific foraging behavior of ant colonies which are able to find, if not the shortest, at least a very good path connecting the colony’s nest with a source of food. Our evaluation of MANETs is based on the evaluation of the mean End-to-End delay to send a packet from source to destination node through a MANET. We evaluated the mean End-to-End delay as one of the most important performance evaluation metrics in computer networks. Finally, we evaluate our proposed ant algorithm by a comparative study with respect to one of the famous On-Demand (reactive) routing protocols called Ad hoc On-Demand Distance Vector (AODV) protocol. The evaluation shows that, the ant algorithm provides a better performance by reducing the mean End-to-End delay than the AODV algorithm. We investigated various simulation scenarios with different node density and pause times. Our new algorithm gives good results under certain conditions such as, increasing the pause time and decreasing node density. The scenarios that are applied for evaluating our routing algorithm have the following assumptions: 2-D rectangular area, no obstacles, bi-directional links, fixed number of nodes operate for the whole simulation time and nodes movements are performed according to the Random Waypoint Mobility (RWM) or the Boundless Simulation Area Mobility (BSAM) model. KEYWORDS: Ant Colony Optimization (ACO), Mobile Ad hoc Network (MANET), Queuing Network Analysis, Routing Algorithms, Mobility Models, Hybrid Simulation

Study of Obstacle effect on the GPSR protocol and a Novel Intelligent Greedy Routing protocol for VANETs

In recent years, connected vehicle technologies have been developed by automotive companies, academia, and researchers as part of Intelligent Transportation Systems (ITS). This group of stakeholders continue to work on these technologies to make them as reliable and cost-effective as possible. This attention is because of the increasing connected vehicles safety-related, entertainment, and traffic management applications, which have the potential to decrease the number of road accidents, save fuel and time for millions of daily commuters worldwide. Vehicular Ad-Hoc Network (VANET), which is a subgroup of Mobile Ad-Hoc Network (MANET), is being developed and implemented in vehicles as the critical structure for connected vehicles applications. VANET provides a promising concept to reduce the number of fatalities caused by road accidents, to improve traffic efficiency, and to provide infotainment. To support the increasing number of safety-related applications, VANETs are required to perform reliably. Since VANETs promise numerous safety applications requiring time-bound delivery of data packets, it is also necessary to replicate real-world scenarios in simulations as accurately as possible. Taking into account the effect of realistic obstacles while simulating a variety of case scenarios increases the reliability of the tested routing protocol to appropriately perform in real-world situations. It also exposes routing protocols to possible vulnerabilities caused by obstacles. Nevertheless, it is not uncommon for researchers to omit real-world physical layer communication hurdles in simulation-based tests, including not considering the effect of obstacles on their routing protocol performance evaluation simulations. Consequently, the performance of these protocols is usually overestimated and do not support in real-world environment. Failure to account for obstacle effects overstate the network performance. In this thesis, a framework for measuring obstacle effects on routing protocols is defined. We also propose, a new routing protocol based on the traditional Greedy Perimeter Stateless Routing (GPSR) protocol called Intelligent Greedy Routing (IGR) protocol. The proposed IGR protocol considers a parameter called $Receptivity$ to chose the next hop in a route. We implemented the new protocol using the Simulation of Urban Mobility (SUMO) and the Network Simulator (NS-3). An analysis of Packet Delivery Ratio (PDR), End-to-End Delay (E2ED) and Mean Hop count with the assumption that nodes (vehicles) are moving in various topologies is presented in this thesis. The study presented here gives a general idea of the effects of obstacles on the Greedy Perimeter Stateless Routing (GPSR) protocol considering multiple realistic scenarios such as Urban, Residential and Highway. In addition, we compare the performance of GPSR and the new IGR protocols with the presence of obstacles considering various topologies. The new proposed IGR protocol performs better compared to the traditional GPSR for all the investigated metrics

Smart Sensor Technologies for IoT

The recent development in wireless networks and devices has led to novel services that will utilize wireless communication on a new level. Much effort and resources have been dedicated to establishing new communication networks that will support machine-to-machine communication and the Internet of Things (IoT). In these systems, various smart and sensory devices are deployed and connected, enabling large amounts of data to be streamed. Smart services represent new trends in mobile services, i.e., a completely new spectrum of context-aware, personalized, and intelligent services and applications. A variety of existing services utilize information about the position of the user or mobile device. The position of mobile devices is often achieved using the Global Navigation Satellite System (GNSS) chips that are integrated into all modern mobile devices (smartphones). However, GNSS is not always a reliable source of position estimates due to multipath propagation and signal blockage. Moreover, integrating GNSS chips into all devices might have a negative impact on the battery life of future IoT applications. Therefore, alternative solutions to position estimation should be investigated and implemented in IoT applications. This Special Issue, “Smart Sensor Technologies for IoT” aims to report on some of the recent research efforts on this increasingly important topic. The twelve accepted papers in this issue cover various aspects of Smart Sensor Technologies for IoT