Christophe Loyez

Using enhanced-TDOA measurement for indoor positioning

In the field of ad hoc networks, maintaining connectivity and performing efficient energy communication between several mobile stations (MS), involves the use of optimized geo localization based routing algorithms. With multipath contribution, indoor location based on a direct time difference of arrival (TDOA) measurement can dramatically increase its budget error and asks for innovative solutions allowing accurate time-of-flight measurement. A natural way of exploiting multiband ultrawide-band (UWB) technology, a simple input and multiple output (SIMO) approach can lead to the measurement of an enhanced TDOA (E-TDOA) measurement for accurate positioning.

Potentials of radio over multimode fiber systems for the in-buildings coverage of mobile and wireless LAN applications

We evaluate the transmission of digital signal modulated on radio-frequency subcarriers through multimode fiber (MMF) by using low-cost 850-nm vertical-cavity surface-emitting lasers and 50-/spl mu/m/62.5-/spl mu/m-core matched receptacle photodiodes. Several mobile telecommunication and wireless local area network standards have been transmitted through standard (500 MHz/spl middot/km) and high bandwidth (1500 and 2000 MHz/spl middot/km) Corning Infinicor SXi and SX+ MMF under different lengths (100, 300, and 600 m). Characterization has been carried out to measure error vector magnitude (EVM) variation as a function of fiber type and length. EVM minor to IEEE and ETSI requirements are obtained for all standards being tested such as IEEE 802.11 g with 1.8% root-mean-square for 300 m of 50-/spl mu/m-core standard MMF at 850 nm.

UWB in Millimeter Wave Band With Pulsed ILO

A simple but efficient transmitter for ultra-wide-band impulse radio wavelet generator in millimeter-wave band is presented. It is suitable for RADAR, gigabit wireless personal area network, and localization applications. This front-end involves a subharmonic injection-locked oscillator driven by a pulse generator (PG) with fast transition time (<25 ps). Its frequency oscillation is locked on one of the numerous harmonic components generated by the PG around 30 GHz. This allows to obtain a stable pulse-to-pulse phase condition and a very low phase noise (<-110 dBc/Hz@100 kHz). Two monolithic microwave integrated circuits have been designed using a commercial pseudomorphic high-electron mobility transistor foundry process (ft = 100 GHz). The first one is a PG with position and width modulation capabilities, and the second one is an oscillator with a 30-GHz free-running output frequency. The start of the oscillations is studied, using the external quality factor as main factor.

Transposition of a baseband UWB signal at 60 GHz for high data rate indoor WLAN

The purpose of this letter is to demonstrate the high potentiality in terms of data rate and multiple access of a novel 60-GHz WLAN architecture for smart objects and indoor communication systems. This approach is based on the up-conversion of an ultrawide-bandwidth impulse radio signal (IR-UWB) in the 60-GHz frequency range to benefit of the natural advantages of the UWB technique while avoiding the baseband limitations. First results about the pulse generator and receiver architecture are discussed.

Review of Glass and Polymer Multimode Fibers Used in a Wimedia Ultrawideband MB-OFDM Radio Over Fiber System

In this paper, we have exhibited the potential of the glass- and polymer-based multimode fibers to be used in a radio over fiber (ROF) system in order to extend the indoor coverage of the Wimedia multiband orthogonal frequency division multiplexing (MB-OFDM) ultrawideband (UWB) standard. After the design of a test setup operating at 850 nm, we have performed the physical characterization of the ROF system especially the mask test compliance, the error vector magnitude (EVM), or the relative constellation error (RCE) variation as a function of the system parameters [radio frequency (RF) power, optical attenuation, fiber length, laser bias current]. The transmission performance of both 200 and 480 Mb/s Wimedia signals is demonstrated through a 100 m link length of glass- and polymer-based multimode fibers: transmission penalties are quantified by RCE with values under the standard requirements. Two different behaviors depending on the core material of the fiber have been identified in this study.

Pulse generator for UWB communication and radar applications with PPM and time hopping possibilities

Two simple and compact ultra-wideband, ultra-short-pulse transmitters have been developed using a monolithic microwave integrated circuit (MMIC). These pulse generators include a digital approach for the pulse forming based on a logic gate. They produce pulses with a variable width as low as 65 ps and rise and fall time about 25 ps (measured). The pulse position modulation (PPM) with pulse frequency rate (PRF) from frequency below 1 MHz to several GHz is also possible. Finally, an analog filtering solution for its shape is proposed in order to be compliant with the FCC part 15 frequency mask

A Distributed Antenna System for Indoor Accurate WiFi Localization

Specific infrastructures are a key challenge for indoor geo-localization systems. In particular, an accurate narrowband localization technique using 802.11 g WiFi signals is proposed in this letter. The related system architecture is built on the basis of radio over fiber topology of distributed antennas systems that are increasingly deployed in buildings. In particular, the system proposed collects the microwave signals using remote and local access points linked by 62.5-μm core diameter multimode fibers and enables to determine the location transmitter with an accuracy of less than 6.4 cm.

A 4-fJ/Spike Artificial Neuron in 65 nm CMOS Technology

As Moores law reaches its end, traditional computing technology based on the Von Neumann architecture is facing fundamental limits. Among them is poor energy efficiency. This situation motivates the investigation of different processing information paradigms, such as the use of spiking neural networks (SNNs), which also introduce cognitive characteristics. As applications at very high scale are addressed, the energy dissipation needs to be minimized. This effort starts from the neuron cell. In this context, this paper presents the design of an original artificial neuron, in standard 65 nm CMOS technology with optimized energy efficiency. The neuron circuit response is designed as an approximation of the Morris-Lecar theoretical model. In order to implement the non-linear gating variables, which control the ionic channel currents, transistors operating in deep subthreshold are employed. Two different circuit variants describing the neuron model equations have been developed. The first one features spike characteristics, which correlate well with a biological neuron model. The second one is a simplification of the first, designed to exhibit higher spiking frequencies, targeting large scale bio-inspired information processing applications. The most important feature of the fabricated circuits is the energy efficiency of a few femtojoules per spike, which improves prior state-of-the-art by two to three orders of magnitude. This performance is achieved by minimizing two key parameters: the supply voltage and the related membrane capacitance. Meanwhile, the obtained standby power at a resting output does not exceed tens of picowatts. The two variants were sized to 200 and 35 μm2 with the latter reaching a spiking output frequency of 26 kHz. This performance level could address various contexts, such as highly integrated neuro-processors for robotics, neuroscience or medical applications.

Energy-Autonomous Picocell Remote Antenna Unit for Radio-Over-Fiber System Using the Multiservices Concept

The study reported in this letter deals with the extension of the multiservices concept to radio-over-fiber systems with energy-autonomous picocell remote antenna units. Continuous-power, radio-frequency, and digital signals have been combined in a single multimode fiber for the first time. The results clearly demonstrate no impairment of the optically powered remote antenna unit compared to an electrically powered version. The proposed system complies with the classical baseband Ethernet high-data-rate network (10 GbE bit error rate 10-12). The measured error vector magnitude for the radio-frequency (IEEE802.11g) signal transmission through the designed system stays around 2%, including both the optical transmission over 100-m OM3 multimode fiber and a wireless coverage of 5 m.

Millimeter Wave Ultra Wide Band Short Range Radar Localization Accuracy

In the coming years, it is expected that long and short range road vehicle radars (LRR, SRR) will all operate at millimeter wave. In several regions of the world, a one GHz bandwidth was selected between 76 and 77 GHz for LRR. To obtain a very high distance resolution for applications like brakeassist and pre-crash, SRR need an even larger bandwidth. Hence, a 4 GHz bandwidth was allocated to provide precise radial range information of objects with a range separation of approximately 5 cm to 10 cm. Directions of the targets are obtained using two or more separate sensors associated to localization techniques. The purpose of this paper concerns a simulation and experimental evaluation of an impulse radio, ultra wide band (IR-UWB) vehicle localization system. In this context, different localization techniques (TDOA, TOA, DOA) will be evaluated in terms of position error for scenarios using three distant, separate sensors. Our objective is to evaluate an optimum technique as a function of the localization range. Simulation results will be compared to experimental results obtained in laboratory. These results will show the interest of coupling two of the following TOA, TDOA and DOA techniques, at different ranges. Keywords-Radar; Ultra Wide Band; Pulse; Ranging; Localization; Vehicle