Petar Solic

Energy Efficient Tag Estimation Method for ALOHA-based RFID systems

Radio frequency identification (RFID) technology has become an important tool for items identification and tracking. Its rapid deployment in dynamic industry areas enables variety of new applications in behavioral analysis and processes automation. In such systems it is crucial to identify all RFID tags before they leave the interrogation area. To accomplish fast identification, it is necessary to estimate a number of tags which are in the reader interrogation area. In this paper, we revisit the problem of tag quantity estimate and adapting frame size of dynamic frame slotted ALOHA widely used as RFID medium access control mechanism. The main disadvantage in the implementation of the state-of-the-art estimation algorithms includes the number of required computations, along with the temporary storage of large numbers which appear before estimation. As a consequence, such algorithms are energy inefficient and may require specific computer architecture to support the calculus. In order to address stated issues, we present improved linearized combinatorial model algorithm for optimal frame size selection which, due to linear property of the estimator, allows significant reduction in the estimate computation with acceptable tradeoff in accuracy. Simulations analyze the required number of slots to identify tag population and the floating point operation costs required to compute estimate. In addition, to emphasize the importance of reducing computational cost, we give a case study which compares energy consumed by the mobile RFID reader processor to compute the estimate and its energy equivalent of the required radio front-end energy to identify tags.

Probabilistic Modeling of Harvested GSM Energy and its Application in Extending UHF RFID Tags Reading Range

Newer silicon-based consumer electronics became very popular due to its reduction in size, price, and power consumption. One of its applications today is building low-power devices for ubiquitous sensing. Although sensors are low-power devices, they need some energy source to function properly. One of the major challenges today is to develop systems where sensors do not require external power sources, and could be powered using available ambient energy. To address this power issue one could use energy harvesting concepts. In this paper, we present our probabilistic approach used for modeling the possible amount of Global System for Mobile Communication (GSM) energy that could be harvested, including a demonstration of what power levels could be harvested using GSM rectifying antenna (rectenna). In addition to harvesting approach, we propose an application of its usage in increasing the communication range between Radio Frequency Identification (RFID) reader and battery free passive RFID tags.

Software defined radio based implementation of RFID tag in next generation mobiles

Radio Frequency identification (RFID) technology has become important tool for items identification and tracking. In those purposes different types of RFID technologies could be used, depending on its application. Limitations of passive RFID technology, related to tags reading range and confidence in harsh environments, puts restrictions on implementation in the real life scenarios. To overcome the issue, but staying within the standards, we have considered development and implementation of active backscattering tag technology, which significantly improves tag reading range and confidence. Software Defined Radio (SDR) technology is promising technology for building mobiles of multiple radio standards in 4G networks. Regarding stated RFID technologies limitations and SDR technology, we present development and implementation of the Software Defined Radio (SDR) active backscattering tag compatible with the EPCglobal UHF Class 1 Generation 2 (Gen2) RFID standard. Such technology can be used for wide spectra of applications and services. The system is developed and tested on SDR platform. Validity and performances of developed Gen2 SDR tag are shown through actual presented results.

Early Frame Break Policy for ALOHA-Based RFID Systems

Throughput of dynamic frame slotted ALOHA (DFSA) in radio frequency identification (RFID) systems depends on the tags quantity estimate. This paper shows how to apply the slot-by-slot (SbS) estimate approach, along with the policy for the early frame-break. Simulation results show noticeable throughput improvements.

Comparing Theoretical and Experimental Results in Gen2 RFID Throughput

Radio frequency identification (RFID) technology, based on wireless communication between a reader and tags, is the most popular technology for indoor item identification and tracking. Among competing RFID technologies, Gen2 has emerged as the most popular one, due to the best price/performance ratio. In order to communicate with multiple tags, Gen2 RFID systems use dynamic frame slotted ALOHA (DFSA) as a medium access control (MAC) mechanism. To maximize DFSA throughput simple calculations show that the number of tags should equal the DFSA frame size. However, the number of tags in an environment is usually unknown and has to be estimated. So far, significant effort has been invested in estimating the correct number of tags. However, to the best of our knowledge, no one has explored the estimator performance in a real RFID measuring scenario. In this paper, we evaluate the throughput of a real RFID system by using the Software Defined Radio (SDR) technology. Our results show that phenomena related to radio waves propagation and reception have a significantly bigger influence on Gen2 RFID throughput than traditional approaches take into account.

Linearized Combinatorial Model for optimal frame selection in Gen2 RFID system

Radio Frequency Identification (RFID) technology become an important tool for items identification and tracking. In this paper we observe RFID Gen2 communication protocol between the RFID reader and the low-cost battery free passive RFID tags. To establish communication between the reader and tags, Gen2 uses Dynamic Frame Slotted ALOHA (DFSA) Medium Access Control (MAC) layer protocol with Q-Selection algorithm for frame size adaptation. DFSA constraints of Gen2 RFID reader-tag communication may become an issue in the fast identification of all tags in the interrogation area. To identify all tags as soon as possible, DFSA frame size should be selected properly so its throughput is maximized, and that can be achieved only if one can estimate number of interrogated tags correctly. In this paper we present Linearized Combinatorial Model (LCM) algorithm for the optimal frame size adaptation. Developed scheme is implemented and tested on Universal Radio Serial Peripheral 1 (USRP1) Gen2 reader application. Results analysis shows that our scheme outperforms Q-Selection algorithm.

A smart remote elderly monitoring system based on IoT technologies

The aging population phenomenon is more and more increasing. In this context, the elderlys behavioral analysis through the Internet of Things technologies can help to prevent Mild Cognitive Impairment and frailty problems. In particular, since movements and body motility are good indicators of behavioral changes, this work aims to define a reliable system for controlling the position and the body motility of the elderly in unobtrusive, low-cost and low-power way. The system represents the basis of a complete architecture for behavioral analysis and risk detection developed within the City4Age project, funded by the Horizon 2020 Programme of the European Commission.

Gen2 RFID as IoT Enabler: Characterization and Performance Improvement

RFID has become an enabling technology for IoT implementation. In dynamic RFID scenarios, such as smart shops or industrial surroundings, it is crucial to identify every good, with an applied RFID tag, before it leaves the interrogation area. Currently, commercial reader solutions adopt DFSA protocol as a simple MAC that manages the communication between a reader and multiple tags. To increase DFSA throughput (the number of read tags in the unit of time) and thus speed up tag identification, simple calculations show that the number of tags should equal the frame size. However, the literature exhibiting RFID performance shows that tag responsiveness is stochastic, while this has been often neglected when considering the throughput. To investigate the influence and to define related research challenges in the RFID domain, this work provides the idea of the required measurements by using SDR technology, while arguing that PHY and MAC layers should be looked at integrally. If not, tag identification will be delayed, while at the same time unnecessary energy waste will occur. In the measurement campaigns, the metric of TRP is employed, given as tag response probability distribution, which can be used for modeling the MAC layer.

A Novel IoT-aware Smart Parking System based on the integration of RFID and WSN technologies

Enabling a sustainable mobility is one of primary goals of the so-called Smart Cities vision, and in this perspective, the deployment of intelligent parking systems represents a key aspect. This paper presents a novel IoT-aware Smart Parking System based on the jointly use of different technologies, such as RFID, WSN, NFC, and mobile. It is able to collect, in real time, both environmental parameters and information about the occupancy state of parking spaces. To reduce the overall system costs, the possibility to use a solar RFID tag as cars’ detection system has been analyzed. The system allows drivers to reach the nearest vacant parking spot and to pay for the parking fee, by using a customized mobile application. Furthermore, a software application based on RESTful Java and Google Cloud Messaging technologies has been installed on a CS in order to manage alert events. A proof-of-concept has been defined to demonstrate that the proposed solution is able to satisfy real requirements of an innovative Smart Parking System, while preliminary analysis of solar tag usage investigates the feasibility of the proposed detection solution.

Impact of Tag Responsiveness on Gen2 RFID Throughput

It is well known in the research community that the throughput of dynamic frame slotted ALOHA (DFSA) in a radio frequency identification (RFID) system can be maximized when DFSA frame size is set to the number of tags. However, related works often neglect the fact that tag responsiveness is of a stochastic nature, depending on the tag hardware performance in the wireless channel. Therefore, as number of tag responses may not be equal to the number of tags located in the interrogation area, corrections to the standard simulation models should be applied. In this letter, we provide the corrections that are based on tag read probability (TRP) metrics. At first, numerically, TRP was retrieved by the usage of fully configurable open-source software defined radio RFID reader in an indoor nonfading radio channel at the single frequency and constant output power, while considering reliable communication parameters in the environment of single and a pair of commercial Gen2 RFID tags. Then, TRP is statistically modeled, and the implications to the throughput are shown.