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 …

I and i

Over the coming decades, high-definition situationally-aware networks have the potential to create revolutionary applications in the social, scientific, commercial, and military sectors Ultrawide bandwidth (UWB) technology is a viable candidate for enabling accurate localization capabilities through time-of-arrival (TOA)-based ranging techniques These techniques exploit the fine delay resolution property of UWB signals by estimating the TOA of the first signal path Exploiting the full capabilities of UWB TOA estimation can be challenging, especially when operating in harsh propagation environments, since the direct path may not exist or it may not be the strongest In this paper, we first give an overview of ranging techniques together with the primary sources of TOA error (including propagation effects, clock drift, and interference) We then describe fundamental TOA bounds (such as the Cramer-Rao bound and the tighter Ziv-Zakai bound) in both ideal and multipath environments These bounds serve as useful benchmarks in assessing the performance of TOA estimation techniques We also explore practical low-complexity TOA estimation techniques and analyze their performance in the presence of multipath and interference using IEEE 802154a channel models as well as experimental data measured in indoor residential environments

/pdf/ranging-with-ultrawide-bandwidth-signals-in-multipath-illizjdvoz.pdf

Ranging With Ultrawide Bandwidth Signals in Multipath Environments

.............................................................................................................................................................. 6 1 Introduction ............................................................................................................................................. 7 1.1 Motivation .......................................................................................................................................................... 7 1.2 Previous Surveys ............................................................................................................................................. 8 1.3 Overview of Technologies ........................................................................................................................... 9 1.4 Indoor Positioning Applications ............................................................................................................ 11 1.5 Structure of this Work ............................................................................................................................... 14 2 User Requirements ............................................................................................................................. 15 2.1 Requirements Parameters Overview .................................................................................................. 15 2.2 Positioning Requirements Parameters Definition ......................................................................... 17 2.3 Man Machine Interface Requirements ................................................................................................ 19 2.4 Security and Privacy Requirements ..................................................................................................... 20 2.5 Costs .................................................................................................................................................................. 20 2.6 Generic Derivation of User Requirements......................................................................................... 20 2.7 Requirements for Selected Indoor Applications ............................................................................. 21 3 Definition of Terms ............................................................................................................................. 25 3.1 Disambiguation of Terms for Positioning .......................................................................................... 25 3.2 Definition of Technical Terms ................................................................................................................ 27 3.3 The Basic Measuring Principles ............................................................................................................. 29 3.4 Positioning Methods ................................................................................................................................... 31 4 Cameras .................................................................................................................................................. 34 4.1 Reference from 3D Building Models .................................................................................................... 35 4.2 Reference from Images .............................................................................................................................. 36 4.3 Reference from Deployed Coded Targets .......................................................................................... 37 4.4 Reference from Projected Targets ........................................................................................................ 38 4.5 Systems without Reference ..................................................................................................................... 39 4.6 Reference from Other Sensors ............................................................................................................... 40 4.7 Summary on Camera Based Indoor Positioning Systems ........................................................... 40 5 Infrared ................................................................................................................................................... 42 5.1 Active Beacons .............................................................................................................................................. 42 5.2 Imaging of Natural Infrared Radiation ............................................................................................... 43 5.3 Imaging of Artificial Infrared Light ....................................................................................................... 43 5.4 Summary on Infrared Indoor Positioning Systems ....................................................................... 44

Indoor Positioning Technologies

Jamming represents the most serious security threat in the field of wireless sensor networks (WSNs), as it can easily put out of order even WSNs that utilize strong highlayer security mechanisms, simply because it is often ignored in the initial WSN design. The objective of this article is to provide a general overview of the critical issue of jamming in WSNs and cover all the relevant work, providing the interested researcher pointers for open research issues in this field. We provide a brief overview of the communication protocols typically used in WSN deployments and highlight the characteristics of contemporary WSNs, that make them susceptible to jamming attacks, along with the various types of jamming which can be exercised against WSNs. Common jamming techniques and an overview of various types of jammers are reviewed and typical countermeasures against jamming are also analyzed. The key ideas of existing security mechanisms against jamming attacks in WSNs are presented and open research issues, with respect to the defense against jamming attacks are highlighted.

A survey on jamming attacks and countermeasures in WSNs

We describe our experiences deploying BikeNet, an extensible mobile sensing system for cyclist experience mapping leveraging opportunistic sensor networking principles and techniques. BikeNet represents a multifaceted sensing system and explores personal, bicycle, and environmental sensing using dynamically role-assigned bike area networking based on customized Moteiv Tmote Invent motes and sensor-enabled Nokia N80 mobile phones. We investigate real-time and delay-tolerant uploading of data via a number of sensor access points (SAPs) to a networked repository. Among bicycles that rendezvous en route we explore inter-bicycle networking via data muling. The repository provides a cyclist with data archival, retrieval, and visualization services. BikeNet promotes the social networking of the cycling community through the provision of a web portal that facilitates back end sharing of real-time and archived cycling-related data from the repository. We present: a description and prototype implementation of the system architecture, an evaluation of sensing and inference that quantifies cyclist performance and the cyclist environment; a report on networking performance in an environment characterized by bicycle mobility and human unpredictability; and a description of BikeNet system user interfaces. Visit [4] to see how the BikeNet system visualizes a user's rides.

/pdf/the-bikenet-mobile-sensing-system-for-cyclist-experience-10dlzn01m9.pdf

The BikeNet mobile sensing system for cyclist experience mapping

The architecture of a low-power, low-complexity ultra wideband (UWB) impulse radio (IR) transceiver circuit, aimed for low data rate, low-cost applications, is presented. The UWB-ER receiver is based on a non-coherent, energy-based approach, which makes it largely independent of the shape of the transmit waveform and robust to multipath channels. Both transmitter and receiver functionalities are included in the circuit presented. The circuits are designed for 0.35 /spl mu/m CMOS IC technology, and the top-level layout of the transmitter is given. The UWB pulse generator produces a Gaussian monocycle of 340 ps typical width. The UWB-IR transmitter IC occupies a total area of 0.16 mm/sup 2/, and consumes 20 mW with a 3.3 V supply.

An ultra wideband low complexity circuit transceiver architecture for sensor networks

An ultrawide band front-end receiver for low power, low complexity communications system is designed and simulated The receiver consists of an ultra wideband antenna, band-pass filter, low noise amplifier, variable gain amplifier, a Gilbert mixer for squaring and an integrator used for integrating the squared signal The receiver is based on a non-coherent, energy collection approach, which makes the receiver highly independent of the shape of the received waveform The bandwidth of the used signal in the system is 1 GHz at 31 GHz - 41 GHz which is attained by filtering the transmitted signal before and after antenna in transmitter and receiver, respectively The design is made using a SiGe 035 /spl mu/m BiCMOS process provided by Austria Microsystems

Front-end receiver for low power, low complexity non-coherent UWB communications system

The paper presents the architecture of a low power, low complexity ultra wideband (UWB) transceiver circuit. The circuit is designed for low data rate, low cost applications with built in location and tracking capabilities. The system is based on a non-coherent architecture which enables the receiver to be extremely simple and largely insensitive to the transmitted pulse shape. The circuit presented contains the oscillator, the transmitter, the receiver and the baseband digital signal processing (DSP) block. The oscillator contains the quartz oscillator, a delay locked-loop (DLL) and edge combiner for clock multiplication to generate a 528 MHz timing signal for pulse generation. The transmitter contains a second DLL to fix the delay of the UWB pulse, the UWB pulse generator and antenna. The transmitted UWB pulse is presented. The receiver contains low noise amplifier, variable gain amplifier, squaring circuits, integrators for energy collection, 4 bit analogue-to-digital converters (ADC), digital control logic, integrator and gain selection logic block and detection/bit decision block. The circuits are designed in a 0.35 /spl mu/m Si-Ge BiCMOS process from Austria Microsystems.

Low complexity UWB circuit transceiver architecture for low cost sensor tag systems

This paper presents a sensor network with low power, low cost devices based on UWB technology employing TDMA. The low data rate network (of the order of 1 kbs-100 kbps per user) is described which also offers good location and tracking capabilities. The UWB tags consist of low power, low-cost, low-complexity transceivers which operate in conjunction with a number of fixed sensor nodes which calculate the tag position. This paper presents the system concept, UWB transceiver and performance in a multipath environment. Location and tracking is not specifically dealt with in this paper.

A low cost, low power UWB based sensor network

In this paper, the architecture of a non-coherent low-complexity ultra wideband impulse radio (UWB-IR) transceiver architecture for low data rate, low complexity tag based sensor networks is presented. The UWB-IR receiver utilises a non-coherent, energy detection-based approach, which makes it largely independent of the shape of the transmit waveform and robust to multipath channels. The UWB-IR transmitter utilises a delay locked loop (DLL) frequency synthesis approach and UWB monocycle pulse generator. The UWB-IR ASIC is manufactured in 0.35 /spl mu/m SiGe BiCMOS technology. The simulated power consumption of UWB-IR transceiver circuits is 136 mW with 100% duty cycle with a 3.3 V power supply.

L. Stoica

Papers

An ultra wideband low complexity circuit transceiver architecture for sensor networks

Front-end receiver for low power, low complexity non-coherent UWB communications system

Low complexity UWB circuit transceiver architecture for low cost sensor tag systems

A low cost, low power UWB based sensor network

An ultra wideband impulse radio low complexity transceiver architecture for sensor networks