Opportunistic routing in wireless mesh networks

Advances in communication and networking technologies are rapidly making ubiquitous network connectivity a reality. In recent years, Wireless Mesh Networks (WMNs) have already become very popular and been receiving an increasing amount of attention by the research community. Basically, a WMN consists of simple mesh routers and mesh clients, where mesh routers form the backbone of WMN. Due to the limited transmission range of the radio, many pairs of nodes in WMN may not be able to communicate directly, hence they need other intermediate nodes to forward packets for them. Routing in such networks is an important issue and it poses great challenges. Opportunistic Routing (OR) has been investigated in recent years as a way to increase the performance of WMNs by exploiting its broadcast nature. In OR, in contrast to traditional routing, instead of pre-selecting a single specic node to be the next-hop as a forwarder for a packet, an ordered set of nodes (referred to as candidates) is selected as the potential next-hop forwarders. Thus, the source can use multiple potential paths to deliver the packets to the destination. More specically, when the current node transmits a packet, all the candidates that successfully receive it will coordinate with each other to determine which one will actually forward it, while the others will simply discard the packet. This dissertation studies the properties, performance, maximum gain, candidate selection algorithms and multicast delivery issues about Opportunistic Routing in WMNs. Firstly, we focus on the performance analysis of OR by proposing a Discrete Time Markov Chain (DTMC). This model can be used to evaluate OR in terms of expected number of transmissions from the source to the destination. Secondly, we apply our Markov model to compare relevant candidate selection algorithms that have been proposed in the literature. They range from non-optimum, but simple, to optimum, but with a high computational cost. Thirdly, the set of candidates which a node uses and priority order of them have a signicant impact on the performance of OR. Therefore, using a good metric and algorithm to select and order the candidates are key factors in designing an OR protocol. As the next contribution we propose a new metric that measures the expected distance progress of sending a packet using a set of candidates. Based on this metric we propose a candidate selection algorithm which its performance is very close to the optimum algorithm although our algorithm runs much faster. Fourthly, we have investigated the maximum gain that can be obtained using OR. We have obtained some equations that yield the distances of the candidates in OR such that the per transmission progress towards the destination is maximized. Based on these equations we have proposed a novel candidate selection algorithm. Our new algorithm only needs the geographical location of nodes. The performance of our proposal is very close to the optimum candidate selection algorithm although our algorithm runs much faster. Finally, using OR to support multicast is an other issue that we have investigated in this thesis. We do so by proposing a new multicast protocol which uses OR. Unlike traditional multicast protocols, there is no designated next-hop forwarder for each destination in our protocol, thus the delivery ratio is maximized by taking advantage of spatial diversity

Information collection algorithm for vehicular ad-hoc networks (application domain: Urban Traffic Wireless Vehicular Ad-Hoc Networks (VANETs))

Vehicle to vehicle communication (V2VC) is one of the modern approaches for exchanging and generating traffic information with (yet to be realized) potential to improve road safety, driving comfort and traffic control. In this research, we present a novel algorithm which is based on V2V communication, uses in-vehicle sensor information and in collaboration with the other vehicles' sensor information can detect road conditions and determine the geographical area where this road condition exists – e.g. geographical area where there is traffic density, unusual traffic behaviour, a range of weather conditions (raining), etc. The algorithms' built-in automatic geographical restriction of the data collection, aggregation and dissemination mechanisms allows warning messages to be received by any car, not necessarily sharing the identified road condition, which may then be used to identify the optimum route taken by the vehicle e.g. avoid bottlenecks or dangerous areas including accidents or congestions on their current routes. This research covers the middle ground between MANET [1] and collaborative data generation based on knowledge granularity (aggregation). It investigates the possibility of designing, implementing and modelling of the functionality of an algorithm (as part of the design of an intelligent node in an Intelligent Transportation System - ITS) that ensures active participation in the formation, routing and general network support of MANETs and also helps in-car traffic information and real-time control generation and distribution. The work is natural extension of the efforts of several large EU projects like DRIVE [2], GST [3] and SAFESPOT [4]

Recent Advances in Cellular D2D Communications

Device-to-device (D2D) communications have attracted a great deal of attention from researchers in recent years. It is a promising technique for offloading local traffic from cellular base stations by allowing local devices, in physical proximity, to communicate directly with each other. Furthermore, through relaying, D2D is also a promising approach to enhancing service coverage at cell edges or in black spots. However, there are many challenges to realizing the full benefits of D2D. For one, minimizing the interference between legacy cellular and D2D users operating in underlay mode is still an active research issue. With the 5th generation (5G) communication systems expected to be the main data carrier for the Internet-of-Things (IoT) paradigm, the potential role of D2D and its scalability to support massive IoT devices and their machine-centric (as opposed to human-centric) communications need to be investigated. New challenges have also arisen from new enabling technologies for D2D communications, such as non-orthogonal multiple access (NOMA) and blockchain technologies, which call for new solutions to be proposed. This edited book presents a collection of ten chapters, including one review and nine original research works on addressing many of the aforementioned challenges and beyond

Enhanced hop-by-hop routing algorithms for underwater acoustic sensor networks

Underwater Acoustic Sensor Network (UW-ASN) is a wireless network infrastructure applicable in deep ocean to sense, collect and transmit information to seashore data collector. Underwater sensor network consists of sensor nodes disposed in different depths, equipped with a low bandwidth acoustic modem and acts collaboratively to route the packet from one node to another. Underwater routing protocols provide route information to underwater sensor nodes to transmit collected information efficiently using an optimal path. Routing protocol related to UW-ASN is identified with the issues of low energy consumption, high end-to-end delay and shorter network lifetime. These are due to the distribution of unnecessary information packet flooding in route establishment, improper selection of next hop neighbour and inefficient routing path generation. This research develops a routing protocol that will be able to control flooding of hello packet at information distribution phase, to calculate link quality and composite metric cost for next hop selection and to regularly update the energy status in order to achieve optimum balance in routing path. The developed protocol is called Distance based Reliable and Energy Efficient (DREE) consists of three schemes. The first scheme is called distance calculation and information distribution scheme that calculates the distance between potential neighbours and distribute the local information in an energy efficient manner. The second scheme is route planning and data forwarding scheme in which a node calculates the link quality towards its neighbours and selects a path based on physical distance, link quality and node energy information. Finally, the third scheme is energy balancing scheme that provides each node with new energy status of its neighbours on regular basis. DREE is compared with a Reliable and Energy Efficient routing protocol (R-ERP2R) and Depth based Routing (DBR) protocol. Simulation shows that DREE reducing energy consumption in the information distribution phase by 187% and 179% compared to R-ERP2R in random and grid topology respectively. DREE achieves higher packet delivery ratio of 96% with a similar end-to-end delay as R-ERP2R. DREE improves packet delivery ratio by 7% and 13% over R-ERP2R and DBR, with 9.3% and 201% less energy consumption respectively in data forwarding phase. Finally, DREE improves network lifetime by 18% and 74.5% compared to R-ERP2R and DBR protocols

Use case scenarios and preliminary reference model

This document provides the starting point for the development of dependability solutions in the HIDENETS project with the following contents: (1) A conceptual framework is defined that contains the relevant terminology, threats and general requirements. This framework is a HIDENETS relevant subset of existing state-of-the-art views in the scientific dependability community. Furthermore, the dependability framework contains a first list of relevant functionalities in the communication and middleware level, which will act as input for the architectural discussions in HIDENETS work packages (WPs) 2 and 3. (2) A set of 17 applications with HIDENETS relevance is identified and their corresponding dependability requirements are derived. These applications belong mostly to the class of car-tocar and car-to-infrastructure services and have been selected due to their different types of dependability needs. (3) The applications have been grouped in six HIDENETS use cases, each consisting of a set of applications. The use cases will be the basis for the development of the dependability solutions in all other WPs. Together with a description of each use-case, application-specific architectural aspects are identified and corresponding failure modes and challenges are listed. (4) The business impact of dependability solutions for these use cases is analysed. (5) A preliminary definition of a HIDENETS reference model is provided, which contains highlevel architectural assumptions. This HIDENETS reference model will be further developed in the course of the HIDENETS projects in close cooperation with the other WPs, which is the reason why the preliminary version also contains a collection of potential contributions from other WPs that shall be developed and investigated in the course of the HIDENETS project. In summary, the identified use-cases and their requirements clearly show the large number of dependability related challenges. First steps towards technical solutions have been made in this report in the preliminary reference model, whereas the other work-packages have started in the meanwhile to develop such solutions further based on 'middleware technology' (WP2), 'communication protocols' (WP3), 'quantitative analysis methodology' (WP4), and 'design and testing methodology' (WP5

Data Collection in Two-Tier IoT Networks with Radio Frequency (RF) Energy Harvesting Devices and Tags

The Internet of things (IoT) is expected to connect physical objects and end-users using technologies such as wireless sensor networks and radio frequency identification (RFID). In addition, it will employ a wireless multi-hop backhaul to transfer data collected by a myriad of devices to users or applications such as digital twins operating in a Metaverse. A critical issue is that the number of packets collected and transferred to the Internet is bounded by limited network resources such as bandwidth and energy. In this respect, IoT networks have adopted technologies such as time division multiple access (TDMA), signal interference cancellation (SIC) and multiple-input multiple-output (MIMO) in order to increase network capacity. Another fundamental issue is energy. To this end, researchers have exploited radio frequency (RF) energy-harvesting technologies to prolong the lifetime of energy constrained sensors and smart devices. Specifically, devices with RF energy harvesting capabilities can rely on ambient RF sources such as access points, television towers, and base stations. Further, an operator may deploy dedicated power beacons that serve as RF-energy sources. Apart from that, in order to reduce energy consumption, devices can adopt ambient backscattering communication technologies. Advantageously, backscattering allows devices to communicate using negligible amount of energy by modulating ambient RF signals. To address the aforementioned issues, this thesis first considers data collection in a two-tier MIMO ambient RF energy-harvesting network. The first tier consists of routers with MIMO capability and a set of source-destination pairs/flows. The second tier consists of energy harvesting devices that rely on RF transmissions from routers for energy supply. The problem is to determine a minimum-length TDMA link schedule that satisfies the traffic demand of source-destination pairs and energy demand of energy harvesting devices. It formulates the problem as a linear program (LP), and outlines a heuristic to construct transmission sets that are then used by the said LP. In addition, it outlines a new routing metric that considers the energy demand of energy harvesting devices to cope with routing requirements of IoT networks. The simulation results show that the proposed algorithm on average achieves 31.25% shorter schedules as compared to competing schemes. In addition, the said routing metric results in link schedules that are at most 24.75% longer than those computed by the LP

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks