Vehicular Active Safety and Driver Assistant Systems (ASDASs) rely heavily on sensors for achieving their goal of protecting the driver and passengers from potentially dangerous situations.The list of such sensors includes imaging sensors operating in different wavelength bands of the visible (i.e., video cameras) and IR spectrum, as well as ranging sensors such as ultrasonic, radar and lidar.The non-imaging ranging sensors are useful for applications that do not require object recognition/classifi cation or scene understanding, but they generally have poor angular resolution and do not provide much information on the spatial characteristics of objects, making object recognition or classifi cation and lane following diffi cult or impossible using such sensors alone.On the other hand, inexpensive vision sensors can capture the scene image in high spatial resolution and a wide fi eld of view, which makes them ideal for object recognition and lane following under most conditions.The objective of this 'Over the Horizon' (OTH) sensor technology overview is to explore emerging imaging sensor technologies that can lead to signifi cant capability improvement as well as cost reduction for future automotive driver assistance and active safety systems.The technologies covered include visible, IR and hyperspectral imaging systems.We also discuss 3D imaging systems.We provide a summary description of different sensors/systems, system architecture and implementation, as well as cost/performance tradeoffs, technology gaps, deployment scenarios and technology trends in the near-, mid-and long-term.

A time-encoding machine (TEM) based new analog-to-digital converter (ADC) architecture is presented in this paper. The main advantage of this architecture is that it relies on asynchronous process and removes an important performance limiting factor in conventional ADCs: the clock jitter. Therefore, this architecture is suitable for very high speed ADCs. To expand the bandwidth coverage, the compressive sensing techniques is employed to reconstruct sparse signals with very high frequency. The system can run under two different modes: the normal mode where the signal is sampled at above Nyquist rate and the compressive sensing mode. Nonidealities in circuits and system parameter setting tradeoffs are analyzed to determine the best parameters for the system to reach optimal performance.

In this paper, we focus on the design and development of a system simulator that can assess the performance of a direct measurement TPMS in various operational scenarios. Our end goal is to use this TPMS simulator as a virtual test environment for a number of different experimental scenarios and possibly reduce the number of actual physical tests that may be required otherwise.

In this paper, we present a system simulator that can evaluate the performance of direct measurement Tire Pressure Monitoring Systems (TPMS) in various operational scenarios. We also discuss the following capabilities of the simulator: (1) modeling the wireless channel characteristics experienced by the signal between various transmitters and the receiver of a given vehicle, (2) modeling collisions among wireless signals of a given vehicle and those of the nearby vehicles, and (3) quantifying the impact of wireless channel characteristics and collisions among wireless signals on the performance of the TPMS. Using results for hypothetical simulation scenarios, we demonstrate the impact of wireless channel characteristics, receiver sensitivity level, and inter-vehicular interference on the performance of the TPMS.

In this paper, we present a system simulator that can assess the performance of a direct measurement Tire Pressure Monitoring System (TPMS) in various operational scenarios. We also discuss the following capabilities of the simulator: (1) modeling the wireless channel characteristics experienced by the signals between various transmitters and the receiver of a given vehicle, (2) modeling intra-vehicular electromagnetic interference (EMI) as experienced by the wireless signals, and (3) quantifying the impact of wireless channel characteristics and intra-vehicular EMI on the system packet error rate (PER). Using quantitative results for hypothetical simulation scenarios, we demonstrate the impact of different levels of Additive White Gaussian Noise (AWGN) and Amplitude Modulated (AM) Noise on the system PER performance.

Active safety applications for vehicles have been at the forefront of the automotive safety community for a number of years. Cooperative collision warning based on vehicle-to-vehicle radio communications and GPS systems is one such promising active safety application that has evoked considerable interest among automobile manufacturers and research communities worldwide. In this paper, we address one of the key functional components of the cooperative collision warning application, which is, accurate estimation of relative positions of all the neighboring vehicles based on real-time exchange of their individual GPS position coordinates, and then we propose a novel system solution for achieving the same (relative positioning functionality) during persistent GPS outages. Our proposed system solution essentially involves integration of the most suitable set of vehicle clustering, radio based ranging, and relative position coordinate establishment techniques, and based on the results of a comprehensive literature survey, we reason that the two-way reciprocal time of arrival based ranging, and the distributed beacon-less relative positioning techniques may constitute the most viable set for our proposed system solution. Having developed a system simulator to accurately model the functionality of our proposed system solution, we then quantify the impact of various levels of ranging error on the overall performance of the system and thereby assess the functional viability of our proposed system solution. The simulation results look quite promising and support the fact that our proposed system solution can enable relative positioning of vehicles without any GPS information within acceptable levels of positioning accuracy, as required for the 360-degrees cooperative collision warning application

The dedicated short range communication (DSRC) standard (also known as IEEE 802.11p) can be used to enable a number of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) wireless radio communication based active safety and telematics applications. In this paper, we briefly document various experimental measurement scenarios and characterize performance of the DSRC standard based radio modules in ldr Additive White Gaussian Noise (AWGN) wireless channel ldr Line-of-sight, no-vehicle-traffic, street road environment ldr Line-of-sight, parking lot environment with moderate-to- dense (surrounding) vehicle density ldr Line-of-sight, freeway environment with low-to-moderate (surrounding) vehicle density The wireless channel models, derived from performance statistics for above mentioned experimental measurement environments, have been incorporated into a DSRC wireless network simulator, and are being used to quantitatively characterize the large-scale network performances (and functional feasibilities) of several V2V, DSRC wireless communication standard based active safety and telematics applications.

AB s T R A CT In this article, we introduce hybrid free-space optical and RF wircless links as potential technology for designing next-gencration broadband wireless nctworks. We present various design challenges and potential solutions for real-time link performance characterization and adaptation for enhanced performancc during adverse wcather conditions. First, we introduce the hybrid wireless architecture and emphasize its significant role in achieving ubiquitous carrier-grade wireless conncctivity. Second, we propose a link monitoring scheme that accurately reflccts the performance of optical wireless links under various weather conditions. In addition, we examine the role of known link performance rcstoration schcmcs - powcr and data rate control. Third, we propose two novel link restoration schemes that cfficiently utilize the hybrid architccture: dynamic load switching and multihop routing. Finally, the article dcscribes an elaborate field testbed based on thc hybrid architecture and various link restoration techniques. The dynamic load switching schemc is shown to haw a profound impact on the ovcrall hybrid link availability. The results, recorded from the experiments during extreme weather conditions, validate thc impact of thc hybrid architecture concept and conclusively prove the availability and rcliability of the architecture in achieving sustained highspeed wireless connectivity.

Two-way wireless communication subsystems (WCS) for voice and data applications will play a central role in future vehicular telematics systems. We discuss some of the design and hardware implementation choices for such wireless communication systems in this paper. Specifically, the impact of wireless communications infrastructure evolution in the U.S. and advances in enabling hardware technologies on the design choices of WCS are addressed. The paper also presents a radio test-bed based on the CDMA2K 1xRTT communication standard, implemented using an advanced system simulation tool. The motivation behind development of the test-bed is to assess the performance of 'direct IF digitization architecture' for the proposed WCS in various wireless channels for different vehicle velocities. The simulation results will ascertain whether the design is suitable for future vehicular telematics systems.

High susceptibility to adverse atmospheric conditions can severely limit the use of free-space optical systems for critical applications. This paper proposes a new architecture for lasercom systems for proactive adaptability during adverse atmospheric conditions. The hardware and software components of the proposed architecture are described in detail. We also present an in-field lasercom test-bed setup, the wireless channel propagation measurements recorded using the test-bed, and the results to validate the recommended design.

The paper presents spatio-temporal measurements for the peer-to-peer radio channel at a center frequency of 1920 MHz with 140 MHz of radio-frequency bandwidth. The measurements were taken using a spread-spectrum channel sounder and an automated spatial probing system that uses precise computer-controlled positioning and orientation of omnidirectional and directional (30/spl deg/ beamwidth) antennas to measure both the angles-of-arrival and time-delays of multipath components. We use a unitless definition of angular spread which we proposed previously (see Durgin, G.D. and Rappaport, T.S., IEE Electron. Lett., vol.34, no.25, p.2431-2, 1998). Transmitter-receiver configurations include six outdoor-to-outdoor cross-campus locations at Virginia Polytechnic Institute and State University (17-219 ns rms delay spread, 0.36-0.91 angular spread), three outdoor-to-indoor locations (27-34 ns rms delay spread, 0.78-0.98 angular spread), and three indoor-to-indoor locations (29-45 ns rms delay spread, 0.73-0.90 angular spread). The paper also quantitatively describes a trend that shows how angular spread increases with increasing delay spread.

We introduce hybrid free-space optical and RF wireless links as potential technology for designing next-generation broadband wireless networks. We present various design challenges and potential solutions for real-time link performance characterization and adaptation for enhanced performance during adverse weather conditions. First, we introduce the hybrid wireless architecture and emphasize its significant role in achieving ubiquitous carrier-grade wireless connectivity. Second, we propose a link monitoring scheme that accurately reflects the performance of optical wireless links under various weather conditions. In addition, we examine the role of known link performance restoration schemes - power and data rate control. Third, we propose two novel link restoration schemes that efficiently utilize the hybrid architecture: dynamic load switching and multihop routing. Finally, the article describes an elaborate field testbed based on the hybrid architecture and various link restoration techniques. The dynamic load switching scheme is shown to have a profound impact on the overall hybrid link availability. The results, recorded from the experiments during extreme weather conditions, validate the impact of the hybrid architecture concept and conclusively prove the availability and reliability of the architecture in achieving sustained highspeed wireless connectivity.