There is a Will, There is a Way: A New Mechanism for Traffic Control Based on VTL and VANET

Traffic light is regarded as one of the most effective ways to alleviate traffic congestion and carbon emission problems. However, traditional traffic light cannot meet the challenges in traffic regulation posed by the fast growing number of vehicles and increasing complexity of road conditions. In this paper, we propose a dynamic traffic regulation method based on virtual traffic light (VTL) for Vehicle Ad Hoc Network (VANET).

In our framework, each vehicle can express its “will” – the desire of moving forward – and share among one another its “will” – value and related traffic information at a traffic light controlled intersection. Based on the traffic information collected in real time, the virtual traffic light in our scheme can be adaptive to the changing environment.We conducted a number of simulation experiments with different scenarios using network simulator NS3 combined with traffic simulator SUMO. The results demonstrate the viability of our solution in reducing waiting time and improving the traffic efficiency.

Adaptive Lookup Protocol for Two-Tier VANET/P2P Information Retrieval Services

Intelligent transportation system (ITS) services have attracted significant attention in recent years. To support ITS services, architecture is required to retrieve information and data from moving vehicles and roadside facilities in an efficient manner. A two-tier system that integrates low-tier vehicular ad hoc networks (VANETs) and a high-tier infrastructure-based peer-to-peer (P2P) overlay, which can achieve a high lookup success rate and low lookup latency for information retrieval, has been developed. However, conventional information lookups in the two-tier VANET/P2P system may introduce extra lookup messages and latencies because the lookup queries are simultaneously performed over the VANET/P2P networks.

This paper proposes an adaptive lookup protocol for the two-tier VANET/P2P system to improve the efficiency of information retrieval. The proposed protocol uses a Bloom filter, which is a space-efficient data structure, to collect reachability information of road segments; therefore, adaptive routing of queries between low- and high-tier networks according to reachability probability can be employed. Simulations based on the SUMO traffic simulator and QualNet network simulator demonstrate that compared with the conventional two-tier lookup mechanism, the adaptive lookup protocol can reduce the lookup latency by 12%, reduce the P2P lookup overhead by 20%-33%, and achieve a high success rate in information lookups.

Urban travel demand estimation using genetic algorithm

Constant increase in urban road traffic is forcing traffic authorities to confront unavoidable congestion problems these days. This creates new challenges for city planners to generate traffic routes with better designs and improve the existing roads. In order to analyze and improve traffic routes, there is a need to understand movement patterns of major vehicular traffic inside the city. Origin Destination(OD) estimation is one such method for understanding the movement patterns. The objective is to find an optimal OD matrix for city traffic, which is a subtle process for classic algorithms. The solution to this problem is Genetic Algorithm (GA) approach which is a search heuristics to find optimal solution from a set of random solutions.

A Genetic Algorithm approach has been developed to find an optimal OD matrix, showing the actual travel patterns of significant number of vehicles inside the city. Once the best OD matrix is obtained, it yields a big opportunity for traffic planners to analyze and improve traffic scenario. Genetic Algorithm can play a major role in solving complex problems. In this paper, one such problem of estimating OD matrix of a city is discussed and implemented. In conjunction to genetic algorithm, Mean Absolute Percentage Error(MAPE) has been used as a fitness criteria for finding the optimal OD matrix.

A Large-Scale SUMO-Based Emulation Platform

A hardware-in-the-loop simulation platform for emulating large-scale intelligent transportation systems is presented. The platform embeds a real vehicle into SUMO, a microscopic road traffic simulation package. Emulations, consisting of the real vehicle, and potentially thousands of simulated vehicles, are run in real time.

The platform provides an opportunity for real drivers to gain a feel of being in a large-scale connected vehicle scenario. Various applications of the platform are presented.

Performance Evaluation of a VANET Simulation System Using NS-3 and SUMO

In this paper, we investigate the performance of HWMP, OLSR and DD protocols in a VANET crossroad scenario. The mobility patterns of vehicles are generated by means of SUMO (Simulation of Urban Mobility) and as communication protocol simulator is used NS3 (Network Simulator 3). For the simulations, we used IEEE 802.11p standard, Two Ray Ground Propagation Loss Model and sent multiple CBR flows over UDP between 20 source-destination pairs.

We use Packet Delivery Ratio (PDR), throughput and delay as evaluation metrics. We compared the performance of three protocols and the simulation results shows that the DD protocol has better PDR and throughput compared with HWMP and OLSR protocol. However, the DD protocol has a long delay because is a delay tolerant protocol.

Recent open source wireless sensor network supporting simulators: A performance comparison

Any common methodology for functionality research in the field of communication systems engineering is network simulation. There is always the overriding worry when utilizing simulation that the results may not reflect appropriate behavior. Therefore, it is important to recognize the particular strengths and also flaws of such simulators. There are a variety of network simulators, as an illustration, NS-2, NS-3, OMNET++, SWAN, OPNET, Jist, and also GloMoSiM and so forth.

As a result, the selection of any network simulator for assessing investigation function is really a critical activity for researchers. The leading emphasis in this research is usually to examine the particular advanced, open source network simulators based on the parameters, CPU usage, memory usage, computational time period, and also scalibility by simulating a wireless sensor network routing protocol, to identify a best network simulator to the investigation area.

How Tangential Problems Limit Value Creation in IT-Based Service Systems

Service systems create value through interactions among people and technology. Though information technology (IT), such as those that support electronic commerce, are key resources in IT-based service systems, it is the people in the system, the computer system administrators, who play the most critical role in making these systems work. In our ethnographic studies of IT service delivery, we found that system administrators typically spend much time troubleshooting. We observed that while configuration and performance work is often guided by explicit procedures or plans, troubleshooting work is not. Problems are handled case-by-case.

Our observations also reveal that a substantial fraction of time spent troubleshooting is on issues related only tangentially to the primary problem. These tangential problems divert time and energy from the primary problem. Although tangential problems tax the overall service system, there may be opportunities to identify and remediate them to improve overall service delivery and value co-creation.

Proportional Sharing in Distributed Dynamic Spectrum Access-Based Networks

Dynamic spectrum access (DSA) is a promising technology to alleviate the exhaustion of spectral resources. To realize DSA, new technologies that enable fast discovery of the unused spectrum along with efficient spectrum management must be developed. In this paper, we propose a novel scanning algorithm and access etiquette to provide secondary devices differentiated spectrum access in a fully distributed manner.

The proposed solution does not use any common control channel or require any a prior knowledge of primary devices’ usage pattern. More importantly, hardware limitation such as imperfect sensing or lack of strict synchronization between secondary devices are taken into account in our design. A mathematical model and an Opnet-based implementation are also developed to evaluate the performance of the proposed solution in DSA networks.

Analytic Performance Model for State-Based MAC Layer Cooperative Retransmission Protocols

Cooperative retransmission can significantly improve link reliability over lossy and time-varying wireless links. However, comparing retransmission protocols is challenging, and generally requires simplistic assumptions specific to each protocol. In this paper, we develop a general model to evaluate cooperative retransmission protocols with distributed, slot-based contention algorithms. Specifically, we propose to calculate the relay time-out probabilities at a MAC time-slot scale, formulate retransmission outcomes as functions of the time-out probabilities, and derive the probability of a retransmission process for every data frame.

We also propose a Markov extension of our model to characterise the dependency between retransmissions of multiple frames. This enables our model to analyse continuous retransmissions of successive frames. Validated by QualNet simulations, our model can analytically predict the probabilities of cooperative retransmissions with an accuracy of 1%. As a result, direct comparisons between cooperative retransmission protocols become tangible, without implementing the full protocol in a state-based simulator.

OPART: Towards an Open Platform for Abstraction of real-time communication in cross-domain applications

Developing real-time communication in various application fields such as robotics, factory automation, etc. is one the most important steps achieving a deterministic system. However, the development of this step is very complex and requires low level and advanced knowledge about the real-timecommunication systems. This complexity decelerates the developing process specially in cross-domain applications e.g. surgical control applications in Networked Medical Systems (NMS) requiring real-time communication and deterministic system behavior.

General complexities developing real-timecommunication systems are classified. The architecture of an Open Platform for Abstraction of Real-Time Communication (OPART) is introduced for reducing these complexities. The architecture of OPART is based on the Ethernet-based real-time communication protocol openPOWERLINK. An experimental setup of OPART using a medical sensor and actuator is demonstrated.