Marcin Seredynski

A survey of vehicular-based cooperative traffic information systems

This paper summarises the research on cooperative traffic information systems based on vehicular ad hoc networks. Such systems are a promising concept for exchanging traffic information among vehicles. Their application enables reductions in fuel consumption, greenhouse gas emissions and travel time. Three classes of such systems are studied: in-frastructureless solutions based on inter-vehicle communication, infrastructure-based solutions relying on the peer-to-peer paradigm and infrastructure-based systems using client-server architectures. Systems within each class are briefly introduced and their strengths and weaknesses are analysed.

Block Encryption Using Reversible Cellular Automata

Cellular automata (CA) are highly parallel and discrete dynamical systems, whose behavior is completely specified in terms of a local relation. They were successfully applied for simulation of biological systems and physical phenomena and recently to design parallel and distributed algorithms for solving task density and synchronization problems. In this paper CA are applied to construct cryptography algorithms. A new encryption concept based on one dimensional, uniform and reversible CA is proposed. A class of CA with rules specifically constructed to be reversible is used.

Multi-segment Green Light Optimal Speed Advisory

The problem of how to adjust speed of vehicles so that they can arrive at the intersection when the light is green can be solved by means of Green Light Optimal Speed Advisory (GLOSA). The existing GLOSA approaches are single segment, that is, they consider traffic lights independently by providing vehicles with the optimal speed for the segment ahead of the nearest traffic lights. In this article we introduce a new approach-a multi segment GLOSA-according to which several lights in sequence on a vehicles route are taken into account. The speed optimisation process is performed using a genetic algorithm. We assume that a vehicle has access to all traffic light phase schedules that it will encounter on its route. The route is composed of segments divided by traffic lights. The proposed GLOSA provides a driver with speed advisory for each segment according to selected preferences like minimisation of total traveling time or fuel consumption. We demonstrate, that in free-flow conditions such multi-segment GLOSA results in much better results when compared with single-segment approach.

Evolutionary game theoretical analysis of reputation-based packet forwarding in civilian mobile Ad Hoc networks

A mobile wireless ad hoc network (MANET) consists of a number of devices that form a temporary network operating without support of a fixed infrastructure. The correct operation of such a network requires its users to cooperate on the level of packet forwarding. However, a distributed nature of MANET, lack of a single authority, and limited battery resources of participating devices may lead to a noncooperative behavior of network users, resulting in a degradation of the network throughput. Thus, a cooperation enforcement system specifying certain packet forwarding strategies is a necessity is such networks. In this work we investigate general properties of such a system. We introduce a Prisoners Dilemma-based model of packet forwarding and next using an evolutionary game-theoretical approach we demonstrate that cooperation very likely to be developed on the basis of conditionally cooperative strategies similar to the TIT-FOR-TAT strategy.

Modelling the Evolution of Cooperative Behavior in Ad Hoc Networks using a Game Based Model

In this paper we address the problem of cooperation and selfish behavior in ad hoc networks. We present a new game theory based model to study cooperation between nodes. This model has some similarities with the iterated prisoners dilemma under the random pairing game. In such game randomly chosen players receive payoffs that depend on the way they behave. The network gaming model includes a simple reputation collection and trust evaluation mechanisms. In our proposition a decision whether to forward or discard a packet is determined by a strategy based on the trust level in the source node of the packet and some general information about behavior of the network. A genetic algorithm (GA) is applied to evolve strategies for the participating nodes. These strategies are targeted to maximize the throughput of the network by enforcing cooperation. Experimental results show that proposed strategy based approach successfully enforces cooperation maximizing the network throughput

Comparison of Green Light Optimal Speed Advisory approaches

Green Light Optimal Speed Advisory (GLOSA) systems provide drivers with speed advices that allow them to pass traffic lights during green interval. In this article we compare performance of single- and multi-segment GLOSA approaches. In a single-segment GLOSA traffic signals are considered independently, i.e. the system provides vehicles with the optimal speed for the segment ahead of the nearest traffic signals. In a multi-segment GLOSA several signals in a sequence on a vehicles route are taken into account, that is, vehicles receive speed advices for a set of segments ahead of the vehicle. Traveling time and fuel efficiency are used as performance measures. We demonstrate that as long as traffic conditions allow drivers selecting a wide range of speed (e.g. during free-flow) a multi-segment GLOSA results in much better performance when compared with a single-segment approach.

Aspects and trends in realistic VANET simulations

Realistic simulations of Vehicular Ad hoc Networks (VANETs) are necessary to evaluate novel technologies based on such networks and to prove benefits obtained from their implementation. This survey gathers from several research domains aspects that increase the quality of VANET simulations. It explains a multi-fold nature of VANETs and presents main building blocks of their simulation-traffic and network simulators. The paper proposes a comprehensive architecture for VANET simulation platform that focuses on producing reliable results. The architecture contains traffic and network simulators that communicate with each other in a dynamic and bi-directional way. The concept of a realistic traffic generator is introduced. It uses real-world data (e.g. maps, traffic volume counts) to model an activity-based traffic varying in time. The traffic generator aims at reproducing accurate vehicular traces for urban scenario. A higher level of realism can be obtained by modelling of human behaviour with intelligent agents and by the implementation of related subsystems, like traffic management and control or weather factors.

The emerging applications of intelligent vehicular networks for traffic efficiency

Traffic efficiency if one of the key applications of the connected vehicle technology, which uses moving cars as nodes in a network to create a Vehicular Ad hoc Network (VANET). The nodes act as mobile traffic sensors. The technology holds promise for enhancing urban and highway mobility. It is cost-effective alternative to the existing fixed location traffic sensing technologies such as inductive-loop detectors and video image processing systems. In this paper we survey the emerging applications of VANETs for traffic efficiency. We considered green light speed advisory systems, adaptive traffic signals, virtual traffic signals, and cooperative traffic information systems. Topics for future research are suggested. We stress the fact, that due to rebound effects the improvements in traffic efficiency will result in additional vehicle travel (generated traffic). Although net congestion reductions will most likely be observed, it is important to account for rebound effects when evaluating initiatives related to traffic efficiency.

Analysing the development of cooperation in MANETs using evolutionary game theory

A wireless mobile ad hoc network is an autonomous system of mobile nodes, which have to cooperate in packet relaying in order to provide the necessary network functionality. Packet relaying based on reciprocity generates strong cooperation incentives even among purely self-regarding nodes. The necessary distinction between selfish and cooperative participants is provided to a node by its trust system. In this article we analyse the particular case where a reputation system is not present in the network, i.e. nodes use solely their local trust systems. In such a case, whether the cooperation is based on direct or on indirect reciprocity, depends on the information type used by trust systems of the network participants. The influence of two factors on the development of cooperation—the network size and the type of participating nodes—is analysed using evolutionary game theory. Computational experiments demonstrate that, in a small network or in a network with many non-cooperative nodes, the cooperation is more likely to be developed on the basis of both reciprocity mechanisms. On the other hand, a large network and the existence of many unconditionally cooperative nodes favour the development of cooperation on the basis of direct reciprocity.

Evaluation of dynamic communities in large-scale vehicular networks

The topology of vehicular ad hoc networks (VANETs) is highly dynamic due to the mobility of the vehicles and changing traffic conditions in time and space. The development of any efficient service in such networks is challenging and requires thorough understanding of the characteristics and dynamics of the underlying communication topology. This work analyses the connectivity and the potential for creating communities in large-scale and realistic VANETs. In addition, the performance of a state-of-the-art decentralised community detection algorithm is studied in terms of how communities form and evolve when considering real-world vehicular mobility.