Danilo De Donno

Introduction to GPU Computing and CUDA Programming: A Case Study on FDTD [EM Programmer's Notebook]

The recent advent of general-purpose graphics-processing units (GPGPUs) as inexpensive arithmetic-processing units brings a relevant amount of computing power to modern desktop PCs. This thus providing an interesting pathway to the acceleration of several numerical electromagnetic methods. In this paper, we explain how to exploit GPGPU features by examining how the computational time of the Finite-Difference Time-Domain Method can be reduced. The attainable efficiency is demonstrated by providing numerical results achieved on a two-dimensional study of a human-antenna interaction problem.

An UHF RFID Energy-Harvesting System Enhanced by a DC-DC Charge Pump in Silicon-on-Insulator Technology

An RF-DC converter enhanced by a DC-DC voltage booster in silicon-on-insulator technology for UHF radio frequency identification (RFID) energy harvesting is presented in this letter. When the received RF power level is -14 dBm or higher, the system, fabricated on an FR4 substrate using off-the-shelf low-cost discrete components and connected to a flexible dipole antenna, is able to produce 2.4 V DC voltage to power general-purpose electronic devices. As a simple proof of concept, a device comprising microcontroller, temperature sensor, and EEPROM is considered in this work. The experimental results demonstrate the capability of the system to autonomously perform temperature data logging up to a distance of 5 m from a conventional UHF RFID reader used as an RF energy source.

RAMSES: RFID Augmented Module for Smart Environmental Sensing

This paper presents a radio frequency identification (RFID) augmented module for smart environmental sensing (RAMSES), which is a fully passive device with sensing and computation capabilities conceived to explore novel and unconventional RFID applications. RAMSES implements an RF energy-harvesting circuit enhanced by a dc-dc voltage booster in silicon-on-insulator technology, an ultralow-power microcontroller, temperature, light, and acceleration sensors, and a new-generation I2C-RFID chip to wirelessly deliver sensor data to standard RFID EPCglobal Class-1 Generation-2 readers. A preliminary RAMSES prototype, fabricated on a printed circuit board using low-cost off-the-shelf discrete components, has been extensively tested through experiments conducted both in lab and real-world application scenarios. The achieved results have demonstrated the ability of RAMSES to harvest the RF energy emitted by an interrogator placed up to 10 m of distance and autonomously perform sensing, computation, and data communication. To our knowledge, this is the longest range ever reported for fully passive RFID sensors. Furthermore, for applications requiring larger operating distances, RAMSES provides also a battery-assisted passive mode yielding up to 22-m communication range.

A Battery-Assisted Sensor-Enhanced RFID Tag Enabling Heterogeneous Wireless Sensor Networks

This paper presents the design, realization, and experimental validation of a battery-assisted radio frequency identification (RFID) tag with sensing and computing capabilities conceived to explore heterogeneous RFID-based sensor network applications. The tag (hereafter called mote) features an ultra-low-power ferroelectric random-access-memory microcontroller, a LED, temperature and light sensors, three-axis accelerometer, non-volatile storage, and a new-generation I2C-RFID chip for communication with standard UHF EPCglobal Class-1 Generation-2 readers. A preliminary RFID mote prototype, fabricated on a printed circuit board using low-cost discrete components and equipped with a small 225-mAh coin battery, provides an estimated lifetime of 3 years when sensing and computing tasks are performed every 30 s. In addition, the reliable RFID communication range up to 22 m achieved in an indoor scenario represents, to the best of our knowledge, the longest distance ever reported for similar sensor-enhanced RFID tags.

A Cost-Effective SDR Platform for Performance Characterization of RFID Tags

The rigorous characterization of ultrahigh-frequency passive radio-frequency identification (RFID) tags is a challenging but mandatory task. Indeed, tags are the most critical devices in RFID systems: their performance should be adequately good, although stringent requirements in terms of compactness, used materials, and costs must be satisfied. Factors such as the goodness of the conjugate impedance matching between the chip and the antenna, the chip sensitivity, and the quality of the backscattered signal affect tag performance. Tag sensitivity and differential radar cross section (RCS) are the most significant metrics for tag characterization: they define the forward (from the reader to the tag) and the backward (from the tag to the reader) link reliability, respectively. Nevertheless, measurement of such metrics cannot be approached with conventional methods based on vector network analyzers or conventional RFID readers. Vice versa, commercially available instrumentation and solutions are very expensive and not totally flexible. In this paper, a novel approach for performance characterization of RFID tags is explored. To this end, we developed a very cheap (below

Listening to Tags: Uplink RFID Measurements With an Open-Source Software-Defined Radio Tool

1000) and flexible tool based on software-defined radio, which enables measurement of tag sensitivity and differential RCS. An exhaustive experimental campaign has been carried out on ten commercial and four built-in laboratory RFID tags. Achieved results demonstrate the flexibility, accuracy, and appropriateness of the proposed approach.

Deploying multiple interconnected gateways in heterogeneous wireless sensor networks: An optimization approach

We present the software-defined radio (SDR) implementation of a Radio Frequency IDentification (RFID) Listener, a passive receive-only device that decodes the signals exchanged between the RFID Reader and the interrogated Tag following the Electronic Product Code Class-1 Generation-2 standard. Our RFID Listener is based on the open-source project GNU Radio. It provides complete flexibility and full control over the entire protocol stack down to the physical layer. As such, it can be used as a powerful but inexpensive tool for testing and measuring the performance of RFID systems in real operating conditions. In this paper, we leverage the SDR Listener for a number of experiments that, taken collectively, are illustrative of the potential of such tool for RFID research. First, we use it to test comparatively different timing recovery schemes for the reception of the Tag signal in uplink, through the analysis of bit-error statistics measured experimentally. We find that the scheme proposed by Harris and Rice based on polyphase filter bank displays excellent performance in this context, very close to the theoretical bound and with a gain of 5 dB over the more common Mueller and Muller scheme. Second, we use the Listener to evaluate the impact of frequency nulls in the uplink RFID channel for different indoor scenarios. We find that frequency nulls are pronounced particularly in the presence of metal objects and obstructions of the Fresnel zone, but frequency hopping is effective in counteracting the problem. Our experiments show that the signal backscattered by a passive Tag can be correctly received up to a distance of 35 m, with low-cost equipment and without highly directional antennas.

Enabling self-powered autonomous wireless sensors with new-generation I 2 C-RFID chips

Data collected by sensors often have to be remotely delivered through multi-hop wireless paths to data sinks connected to application servers for information processing. The position of these sinks has a huge impact on the quality of the specific Wireless Sensor Network (WSN). Indeed, it may create artificial traffic bottlenecks which affect the energy efficiency and the WSN lifetime. This paper considers a heterogeneous network scenario where wireless sensors deliver data to intermediate gateways geared with a diverse wireless technology and interconnected together and to the sink. An optimization framework based on Integer Linear Programming (ILP) is developed to locate wireless gateways minimizing the overall installation cost and the energy consumption in the WSN, while accounting for multi-hop coverage between sensors and gateways, and connectivity among wireless gateways. A traffic-variable scenario is also considered, where the network can go through high and low traffic operation points, and the topology is optimized accordingly. The proposed ILP formulations are solved to optimality for medium-size instances to analyze the quality of the designed networks, and heuristic algorithms are also proposed to tackle large-scale heterogeneous scenarios.

Design and applications of a Software-Defined listener for UHF RFID systems

A self-powered autonomous RFID device with sensing and computing capabilities is presented in this paper. Powered by an RF energy-harvesting circuit enhanced by a DC-DC voltage booster in silicon-on-insulator (SOI) technology, the device relies on a microcontroller and a new generation I2C-RFID chip to wirelessly deliver sensor data to standard RFID EPC Class-1 Generation-2 (Gen2) readers. When the RF power received from the interrogating reader is -14 dBm or higher, the device, fabricated on an FR4 substrate using low-cost discrete components, is able to produce 2.4-V DC voltage to power its circuitry. The experimental results demonstrate the effectiveness of the device to perform reliable sensor data transmissions up to 5 meters in fully-passive mode. To the best of our knowledge, this represents the longest read range ever reported for passive UHF RFID sensors compliant with the EPC Gen2 standard.

Performance analysis of passive UHF RFID tags with GNU-radio

Conventional RFID readers combine transmission (to the tag) and reception (from the tag) functions in a single physical device. In this paper we discuss the design and potential applications of a receive-only device, called “RFID listener”, that decodes the signals from both the tag and the reader. This enables augmented RFID systems where one transmitter coexists with multiple listeners offering reception redundancy and diversity. We present a Software-Defined Radio (SDR) implementation of an RFID listener compliant with Gen2 standard, which can serve as a research tool for experimenting “on air” novel augmented RFID systems. Moreover, our listener can be used as a flexible and cheap protocol analyzer for conventional reader/tag systems. We present a test-bed setting where our listener and a conventional SDR reader are used in conjunction to measure separately the maximum downlink and uplink range.