V2V Routing in VANET Based on Heuristic Q-Learning

Designing efficient routing algorithms in vehicular ad hoc networks (VANETs) plays an important role in the emerging intelligent transportation systems. In this paper, a routing algorithm based on the improved Q-learning is proposed for vehicle-to-vehicle (V2V) communications in VANETs. Firstly, a link maintenance time model is established, and the maintenance time is taken as an important parameter in the design of routing algorithm to ensure the reliability of each hop link. Aiming at the low efficiency and slow convergence of Q-learning, heuristic function and evaluation function are introduced to accelerate the update of Q-value of current optimal action, reduce unnecessary exploration, accelerate the convergence speed of Q-learning process and improve learning efficiency. The learning task is dispersed in each vehicle node in the new routing algorithm and it maintains the reliable routing path by periodically exchanging beacon information with surrounding nodes, guides the node’s forwarding action by combining the delay information between nodes to improve the efficiency of data forwarding. The performance of the algorithm is evaluated by NS2 simulator. The results show that the algorithm has a good effect on the package delivery rate and end-to-end delay

Adaptive Hybrid Routing Protocol for VANETs

Within VANETs, vehicle mobility will cause the communication associations between vehicles to deteriorate. Hybrid routing is necessary as one size fits all approach is not suitable for VANET?s due to diversity in the infrastructure consisting of mobile nodes, stationary nodes, road-side units (RSU), control centres etc. Therefore, in the proposed system, we implement a hybrid design methodology, where we syndicate features of reactive routing (AODV) with geographic routing and proactive routing protocol. Adaptive Hybrid Routing Protocol(AHR), vehicles use proactive routing protocol for V2I communication and reactive routing protocol with geographic routing protocol for V2V communication. The system integrates features of both reactive and geographic routing protocols along with proactive routing schemes. It combines these routing protocols in a manner that efficiently uses all the location information available and exit to reactive routing as the location information degrades. As compared to the existing standard routing protocols, the analysis and simulations show that the routing overhead has been significantly reduced. It demonstrates how such a performance enhancement would yield a scalable and efficient routing solution in the context of VANET environments. Even in the occurrence of location errors, proposed system works efficiently and obtains scalable performance, thus making it an optimal protocol for VANETs

Enhancing the VANET Network Layer

The aim of this thesis is to examine existing VANET network layer functionality and to propose enhancements to the VANET network layer to facilitate vehicular (V2X) communication. This thesis proposes three enhancements to the VANET network layer which address many of the issues with V2X communication, these enhancements are: a geographic overlay allowing vehicles to localize themselves; an IPv6 addressing strategy which embeds positional information within an IP address allowing for location based routing; and finally a novel position based routing protocol which has two primary advantages over existing protocols, firstly removing unnecessary overhead information and control communication, and secondly support for multiple types of V2X communication models. The simulation results show that the proposed enhancements are well suited in low and medium vehicular density environments. Based on the observed behaviors the author recommends further modification and study of position based routing protocols

Position-Based Packet Forwarding for Vehicular Ad-Hoc Networks

Mobile Ad-Hoc Networks, or MANETs, are data communication networks between (potentially) mobile computer systems equipped with wireless communication devices and — in their purest form — in complete absence of communication infrastructure. Usage scenarios for these systems include communication during disaster recovery or battlefield communications. One of the great research challenges concerning MANETs is the Packet Forwarding Problem, i.e., the question to which neighbor node a data packet should be handed over to reach non-neighboring nodes. While this problem has been previously solved by the adaption of classic routing algorithms from wired networks, the availability of GPS enables to include information about the geographic position of nodes into the routing decision, by selecting forwarders that are geographically closest to the destination. While these algorithms have been shown to improve communication performance in networks with a high degree of node mobility, they require (a) a beaconing service that allows every node to build a table of its neighbors and (b) a so-called Location Service that allows to acquire the current position of non-neighboring nodes in the network. In this thesis, we propose Contention-Based Forwarding (or CBF), a greedy routing heuristic that is no longer in need of a beaconing service. Moreover, a forwarding node running CBF does not at all select the next forwarder explicitly but broadcasts the packet containing its own position and the position of the destination. The selection of the forwarding is now done in a contention period, where every possible forwarder, i.e., every receiver of the packet, considers its own suitability to forward by calculating the geographical progress for the packet if forwarded by itself. Then it waits for a time reciprocal to this suitability before simply retransmitting. If the retransmission of a packet is overheard, the own postponed retransmission process is canceled. In this thesis, we demonstrate that CBF outperforms beacon and position-based routing by delivering packets with constant overhead, almost ignorant of mobility. Also, we introduce two strategies to cope with the problem of packet duplication. A problem left open by greedy routing heuristics is routing in the presence of local optima, or voids. Voids are node placement situations, where — in spite of an existing route — no neighboring node is geographically closer to the destination than the current forwarder. In these situations, greedy forwarding fails and standard graph-based recovery well known from classical Position-Based Forwarding cannot be applied due to the lack of the beacon-based construction of neighbor tables. As a solution, we propagate Contention-Based Distance Vector Routing, a contention-based adaption of AODV that acquires topology information in the area of the void and does contention on the topological distance to the forwarder. Besides the forwarding algorithms, we extend position-based routing by two location services. The first, the Reactive Location Service or RLS is simple, purely on-demand and very robust to mobility, the second Hierarchical Location Service, is more complex but outperforms RLS in scalability. The second big column in this thesis is ad-hoc multi-hop communication in the context of Vehicular Ad-Hoc Networks , or VANET, i.e., networks where the communication system is carried by vehicles. These systems very elegantly fit into the propositions and requirements for our more general routing approaches since they have (a) easy access to position information an (b) "suffer" from high mobility. For VANETs, we separate the routing problem into highway and city scenarios and study various routing algorithms in both. In the end, we advocate the usage of position-based routing in both scenarios; moreover, the contention-based approaches are most promising. While a lot of ad-hoc research has been deemed to be theoretical, we have also built a multi-car communication system. For this system, we provided the network and system architecture and provided the communication software. In this thesis, we will describe these efforts as a proof-of-concept and provide measurement results

SDN-based VANET routing: A comprehensive survey on architectures, protocols, analysis, and future challenges

As the automotive and telecommunication industries advance, more vehicles are becoming connected, leading to the realization of intelligent transportation systems (ITS). Vehicular ad-hoc network (VANET) supports various ITS services, including safety, convenience, and infotainment services for drivers and passengers. Generally, such services are realized through data sharing among vehicles and nearby infrastructures or vehicles over multi-hop data routing mechanisms. Vehicular data routing faces many challenges caused by vehicle dynamicity, intermittent connectivity, and diverse application requirements. Consequently, the software-defined networking (SDN) paradigm offers unique features such as programmability and flexibility to enhance vehicular network performance and management and meet the quality of services (QoS) requirements of various VANET services. Recently, VANET routing protocols have been improved using the multilevel knowledge and an up-to-date global view of traffic conditions offered by SDN technology. The primary objective of this study is to furnish comprehensive information regarding the current SDN-based VANET routing protocols, encompassing intricate details of their underlying mechanisms, forwarding algorithms, and architectural considerations. Each protocol will be thoroughly examined individually, elucidating its strengths, weaknesses, and proposed enhancements. Also, the software-defined vehicular network (SDVN) architectures are presented according to their operation modes and controlling degree. Then, the potential of SDN-based VANET is explored from the aspect of routing and the design requirements of routing protocols in SDVNs. SDVN routing algorithms are uniquely classified according to various criteria. In addition, a complete comparative analysis will be achieved to analyze the protocols regarding performance, optimization, and simulation results. Finally, the challenges and upcoming research directions for developing such protocols are widely stated here. By presenting such insights, this paper provides a comprehensive overview and inspires researchers to enhance existing protocols and explore novel solutions, thereby paving the way for innovation in this field

Road-based routing in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) can provide scalable and cost-effective solutions for applications such as traffic safety, dynamic route planning, and context-aware advertisement using short-range wireless communication. To function properly, these applications require efficient routing protocols. However, existing mobile ad hoc network routing and forwarding approaches have limited performance in VANETs. This dissertation shows that routing protocols which account for VANET-specific characteristics in their designs, such as high density and constrained mobility, can provide good performance for a large spectrum of applications. This work proposes a novel class of routing protocols as well as three forwarding optimizations for VANETs. The Road-Based using Vehicular Traffic (RBVT) routing is a novel class of routing protocols for VANETs. RBVT protocols leverage real-time vehicular traffic information to create stable road-based paths consisting of successions of road intersections that have, with high probability, network connectivity among them. Evaluations of RBVT protocols working in conjunction with geographical forwarding show delivery rate increases as much as 40% and delay decreases as much as 85% when compared with existing protocols. Three optimizations are proposed to increase forwarding performance. First, one- hop geographical forwarding is improved using a distributed receiver-based election of next hops, which leads to as much as 3 times higher delivery rates in highly congested networks. Second, theoretical analysis and simulation results demonstrate that the delay in highly congested networks can be reduced by half by switching from traditional FIFO with Taildrop queuing to LIFO with Frontdrop queuing. Third, nodes can determine suitable times to transmit data across RBVT paths or proactively replace routes before they break using analytical models that accurately predict the expected road-based path durations in VANETs

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

Secure multi-constrained QoS reliable routing algorithm for vehicular ad hoc networks (VANETs)

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonVehicular Ad hoc Networks (VANETs) are a particular form of wireless network made by vehicles communicating among themselves and with roadside base stations. A wide range of services has been developed for VANETs ranging from safety to infotainment applications. A key requirement for such services is that they are offered with Quality of Service (QoS) guarantees in terms of service reliability and availability. Furthermore, due to the openness of VANET’s wireless channels to both internal and external attacks, the application of security mechanisms is mandatory to protect the offered QoS guarantees. QoS routing plays an essential role in identifying routes that meet the QoS requirements of the offered service over VANETs. However, searching for feasible routes subject to multiple QoS constraints is in general an NP-hard problem. Moreover, routing reliability needs to be given special attention as communication links frequently break in VANETs. To date, most existing QoS routing algorithms are designed for stable networks without considering the security of the routing process. Therefore, they are not suitable for applications in VANETs. In this thesis, the above issues are addressed firstly by developing a link reliability model based on the topological and mathematical properties of vehicular movements and velocities. Evolving graph theory is then utilised to model the VANET communication graph and integrate the developed link reliability model into it. Based on the resulting extended evolving graph model, the most reliable route in the network is picked. Secondly, the situational awareness model is applied to the developed reliable routing process because picking the most reliable route does not guarantee reliable transmission. Therefore, a situation-aware reliable multipath routing algorithm for VANETs is proposed. Thirdly, the Ant Colony Optimisation (ACO) technique is employed to propose an Ant-based multi-constrained QoS (AMCQ) routing algorithm for VANETs. AMCQ is designed to give significant advantages to the implementation of security mechanisms that are intended to protect the QoS routing process. Finally, a novel set of security procedures is proposed to defend the routing process against external and internal threats. Simulation results demonstrate that high levels of QoS can be still guaranteed by AMCQ even when the security procedures are applied

Unmanned Aerial ad Hoc Networks: Simulation-Based Evaluation of Entity Mobility Models’ Impact on Routing Performance

An unmanned aerial ad hoc network (UAANET) is a special type of mobile ad hoc network (MANET). For these networks, researchers rely mostly on simulations to evaluate their proposed networking protocols. Hence, it is of great importance that the simulation environment of a UAANET replicates as much as possible the reality of UAVs. One major component of that environment is the movement pattern of the UAVs. This means that the mobility model used in simulations has to be thoroughly understood in terms of its impact on the performance of the network. In this paper, we investigate how mobility models affect the performance of UAANET in simulations in order to come up with conclusions/recommendations that provide a benchmark for future UAANET simulations. To that end, we first propose a few metrics to evaluate the mobility models. Then, we present five random entity mobility models that allow nodes to move almost freely and independently from one another and evaluate four carefully-chosen MANET/UAANET routing protocols: ad hoc on-demand distance vector (AODV), optimized link state routing (OLSR), reactive-geographic hybrid routing (RGR) and geographic routing protocol (GRP). In addition, flooding is also evaluated. The results show a wide variation of the protocol performance over different mobility models. These performance differences can be explained by the mobility model characteristics, and we discuss these effects. The results of our analysis show that: (i) the enhanced Gauss–Markov (EGM) mobility model is best suited for UAANET; (ii) OLSR, a table-driven proactive routing protocol, and GRP, a position-based geographic protocol, are the protocols most sensitive to the change of mobility models; (iii) RGR, a reactive-geographic hybrid routing protocol, is best suited for UAANET