Zafer Sahinoglu

Bio: Zafer Sahinoglu is an academic researcher from Mitsubishi Electric Research Laboratories. The author has contributed to research in topics: Wireless network & Node (networking). The author has an hindex of 39, co-authored 172 publications receiving 7838 citations. Previous affiliations of Zafer Sahinoglu include New Jersey Institute of Technology & Mitsubishi Electric.

Localization via ultra-wideband radios: a look at positioning aspects for future sensor networks

Abstract: UWB technology provides an excellent means for wireless positioning due to its high resolution capability in the time domain. Its ability to resolve multipath components makes it possible to obtain accurate location estimates without the need for complex estimation algorithms. In this article, theoretical limits for TOA estimation and TOA-based location estimation for UWB systems have been considered. Due to the complexity of the optimal schemes, suboptimal but practical alternatives have been emphasized. Performance limits for hybrid TOA/SS and TDOA/SS schemes have also been considered. Although the fundamental mechanisms for localization, including AOA-, TOA-, TDOA-, and SS-based methods, apply to all radio air interface, some positioning techniques are favored by UWB-based systems using ultrawide bandwidths.

UWB Systems for Wireless Sensor Networks

Abstract: Wireless sensor networks are emerging as an important area for communications. They enable a wealth of new applications including surveillance, building control, factory automation, and in-vehicle sensing. The sensor nodes have to operate under severe constraints on energy consumption and form factor, and provide the ability for precise self-location of the nodes. These requirements can be fulfilled very well by various forms of ultra-wide-band (UWB) transmission technology. We discuss various techniques and tradeoffs in UWB systems and indicate that time-hopping and frequency-hopping impulse radio physical layers combined with simple multiple-access techniques like ALOHA are suitable designs. We also describe the IEEE 802.15.4a standard, an important system that adopts UWB impulse radio to ensure robust data communications and precision ranging. In order to accommodate heterogeneous networks, it uses specific modulation, coding, and ranging waveforms that can be detected well by both coherent and noncoherent receivers.

Threshold-based TOA estimation for impulse radio UWB systems

Abstract: Highly dispersive nature of ultra-wideband (UWB) channels makes time of arrival (TOA) estimation extremely challenging, where the leading-edge path is not necessarily the strongest path Since the bandwidth of a received UWB signal is very large, the Nyquist rate sampling becomes impractical, hence motivating lower complexity and yet accurate ranging techniques at feasible sampling rates In this paper, we consider TOA estimation based on symbol rate samples that are obtained after a square-law device A normalized threshold selection approach based on the minimum and maximum values of the energy samples is introduced, and optimal values of the thresholds for different signal to noise ratios (SNRs) are investigated via simulations Also, the effect of window size when searching the leading edge prior to maximum energy block is analyzed Theoretical closed form expressions are derived for mean absolute TOA estimation error for a fixed threshold case Performances of different algorithms are then compared via simulations using IEEE 802154a channel models and by choosing appropriate normalized threshold and search-back window parameters

Environment aware services for mobile devices

Abstract: A system delivers multimedia services to mobile devices via a network by first registering a mobile device with a service manager connected to the mobile device via the network. Application service providers are connected to the service manager via the network. Each application service provider is associated with particular multimedia services. An environment description to be associated with the mobile device is acquired, and a particular application service provider is identified according to the environment description, and then selected services provided by the particular application service provider are delivered to the mobile device according to the environment description via the network.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Survey of Wireless Indoor Positioning Techniques and Systems

Abstract: Wireless indoor positioning systems have become very popular in recent years. These systems have been successfully used in many applications such as asset tracking and inventory management. This paper provides an overview of the existing wireless indoor positioning solutions and attempts to classify different techniques and systems. Three typical location estimation schemes of triangulation, scene analysis, and proximity are analyzed. We also discuss location fingerprinting in detail since it is used in most current system or solutions. We then examine a set of properties by which location systems are evaluated, and apply this evaluation method to survey a number of existing systems. Comprehensive performance comparisons including accuracy, precision, complexity, scalability, robustness, and cost are presented.

Internet of things: Vision, applications and research challenges

Abstract: The term ‘‘Internet-of-Things’’ is used as an umbrella keyword for covering various aspects related to the extension of the Internet and the Web into the physical realm, by means of the widespread deployment of spatially distributed devices with embedded identification, sensing and/or actuation capabilities. Internet-of-Things envisions a future in which digital and physical entities can be linked, by means of appropriate information and communication technologies, to enable a whole new class of applications and services. In this article, we present a survey of technologies, applications and research challenges for Internetof-Things.

Locating the nodes: cooperative localization in wireless sensor networks

Abstract: Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of applications. In cooperative localization, sensors work together in a peer-to-peer manner to make measurements and then forms a map of the network. Various application requirements influence the design of sensor localization systems. In this article, the authors describe the measurement-based statistical models useful to describe time-of-arrival (TOA), angle-of-arrival (AOA), and received-signal-strength (RSS) measurements in wireless sensor networks. Wideband and ultra-wideband (UWB) measurements, and RF and acoustic media are also discussed. Using the models, the authors have shown the calculation of a Cramer-Rao bound (CRB) on the location estimation precision possible for a given set of measurements. The article briefly surveys a large and growing body of sensor localization algorithms. This article is intended to emphasize the basic statistical signal processing background necessary to understand the state-of-the-art and to make progress in the new and largely open areas of sensor network localization research.