Wantanee Viriyasitavat

Carnegie Mellon University | CMU · Department of Electrical and Computer Engineering

Recent research has shown that both radio and visible light waves can be used to enable communications in highly dynamic vehicular environments. However, the roles of these two technologies and how they interact with each other in future vehicular communication systems remain unclear. Understanding the propagation characteristics is an essential st...

While both radio and visible light waves can serve as the transmission medium, the propagation channel plays a key role in the highly dynamic vehicular communication environment. We discuss salient properties of radio and visible light channels, including radiation pattern and path loss modeling. By comparing their similarities and highlighting the...

Prior work has shown that a biologically inspired approach can solve some of the fundamental transportation problems in urban areas. As one instance of this approach, it was shown that vehicles equipped with dedicated short-range communications (DSRC) radios can manage traffic in urban areas in a completely self-organized manner similar to self-org...

Efficient message dissemination in vehicular ad-hoc networks (VANETs) is crucial for supporting communication among vehicles and also between users and the Internet, with minimal delay and overhead but maximum reachability. To improve the message dissemination in these networks, we show the need to study the graph-theoretic properties of VANETs, si...

Vehicular communication is characterized by a dynamic environment, high mobility, and comparatively low antenna heights on the communicating entities (vehicles and roadside units). These characteristics make vehicular propagation and channel modeling particularly challenging. In this article, we classify and describe the most relevant vehicular pro...

Systems, methods, software, and apparatuses for coordinating traffic proximate to a potential conflict zone, such as a roadway intersection, where travel conflicts, such as crossing traffic, can arise. Coordination involves forming an ad-hoc network in a region containing the conflict zone using, for example, vehicle-to-vehicle communications and d...

Recent empirical studies have shown that correctly modeling the vehicular channel is imperative for realistic evaluation of VANET applications (Gozalvez et al., Telecommun Syst:1–19, 2010; Dhoutaut et al., Impact of radio propagation models in vehicular ad hoc networks simulations. VANET 06: Proceedings of the 3rd international workshop on Vehicula...

Virtual traffic lights (VTL) is a new technology that holds the promise of revolutionizing traffic control in urban areas. The original VTL idea was based on 100 percent penetration of VTL technology. In this article, contrary to conventional wisdom, it is shown that 100 percent penetration is not a necessary condition for deploying VTL technology...

A new technology known as Virtual Traffic Lights (VTL) was recently proposed as a self-organizing new paradigm for traffic management. This new technology uses the vehicle-to-vehicle (V2V) communications as its premise. VTL can revolutionize traffic management in urban areas as it can substantially reduce commute time of urban workers, increase pro...

Deploying Roadside Units (RSUs) for increasing the connectivity of vehicular ad hoc networks is deemed necessary for coping with the partial penetration of Dedicated Short Range Communications (DSRC) radios into the market at the initial stages of DSRC deployment. Several factors including cost, complexity, existing systems, and lack of cooperation...

Over the past few years, Light Emitting Diode (LED) has become very common in automotive lighting due to its long service life, high resistance to vibration, and better safety performance due to its short rise time. A number of existing works use LEDs that already exist in vehicles, such as brake lights, turn signals, and headlamps, to carry out ve...

We analyze the properties of line of sight (LOS) channels in vehicle-to-vehicle (V2V) communication. We use V2V measurements performed in open space, suburban, and urban environments. By separating LOS from non-LOS data, we show that a two-ray ground reflection path loss model with effective reflection coefficient range fits the LOS channels better...

Virtual Traffic Lights (VTL) is a recently proposed self-organizing traffic control scheme that has the potential to mitigate traffic congestion in urban areas. This paper reports a prototype design effort on Virtual Traffic Lights using Android-based smartphones. The experiments performed show the feasibility of implementing VTL using smartphones'...

Developing routing protocols for Vehicular Ad Hoc Networks (VANETs) is a significant challenge in these large, self- organized and distributed networks. We address this challenge by studying VANETs from a network science perspective to develop solutions that act locally but influence the network performance globally. More specifically, we look at s...

The gradual penetration of Dedicated Short Range Communications Radio (DSRC) technology in the years to come is a formidable problem that could adversely affect the implementation of safety and non-safety applications. In this paper, we propose a solution that might mitigate the negative impact of the partial and gradual penetration problem of DSRC...

Biologically inspired approaches have the potential to solve many of the difficult networking problems awaiting practical solutions. The recently proposed Virtual Traffic Lights (VTL) is one example (or instance) of this powerful approach for solving some fundamental transportation problems[1], [2]. The successful operation of VTL scheme ultimately...

Several vehicular communication applications will involve multicast/broadcast communications where all vehicles in a certain region of interest are the intended recipients of particular messages. While there are several existing broadcast routing protocols for highway VANETs, very few solutions exist for urban VANETs in cities like New York City or...

In emerging non-safety unicast applications of vehicular ad hoc networks (VANETs) such as Internet Access, Content, Map, or Database Download (CMDD), end-to-end (e.g., connection-oriented) transmission control must be employed to guarantee a desired level of performance. Designing a Transport Control Protocol (TCP) in VANETs is a very challenging t...

Vehicular ad hoc networks (VANETs) have emerged as a serious and promising candidate for providing ubiquitous communications both in urban and highway scenarios. Consequently, nowadays it is widely believed that VANETs will be able to support both safety and non-safety applications. For both classes of applications, since a zero-infrastructure is t...

Several vehicular communication applications will involve multicast/broadcast communications where all vehicles in a certain region of interest are the intended recipients of particular messages. While there are several existing broadcast routing protocols for highway VANETs, very few solutions exist for urban VANETs in cities like New York City or...

In this paper we propose and present preliminary results on the migration of traffic lights as roadside-based infrastructures to in-vehicle virtual signs supported only by vehicle- to-vehicle communications. We design a virtual traffic light protocol that can dynamically optimize the flow of traffic in road intersections without requiring any roads...

Modeling complicated vehicular traffic behavior and the associated network connectivity in urban areas has been a challenging task for the past several years. In this paper, we study how intersections and two-dimensional road topology affect the connectivity behavior of traffic in urban areas. To better understand this phenomenon, we investigate bo...

In this article we introduce a new cellular automata approach to construct an urban traffic mobility model. Based on the developed model, characteristics of global traffic patterns in urban areas are studied. Our results show that different control mechanisms used at intersections such as cycle duration, green split, and coordination of traffic lig...

Statistical characterization of in-car wireless communication channels has recently gained significance, mainly due to the possibility of deploying a wireless sensor network in the vehicle. In this paper, we report different aspects of a statistical analysis of four representative in- car wireless channels based on the received power data collected...