Concurrent Backscatter Streaming from Batteryless and Wireless Sensor Tags with Multiple Subcarrier Multiple Access

This paper proposes a novel multiple access method that enables concurrent sensor data streaming from multiple batteryless, wireless sensor tags. The access method is a pseudo-FDMA scheme based on the subcarrier backscatter communication principle, which is widely employed in passive RFID and radar systems. Concurrency is realized by assigning a dedicated subcarrier to each sensor tag and letting all sensor tags backscatter simultaneously. Because of the nature of the subcarrier, which is produced by constant rate switching of antenna impedance without any channel filter in the sensor tag, the tag-to-reader link always exhibits harmonics. Thus, it is important to reject harmonics when concurrent data streaming is required. This paper proposes a harmonics rejecting receiver to allow simultaneous multiple subcarrier usage. This paper particularly focuses on analog sensor data streaming which minimizes the functional requirements on the sensor tag and frequency bandwidth. The harmonics rejection receiver is realized by carefully handling group delay and phase delay of the subcarrier envelope and the carrier signal to accurately produce replica of the harmonics by introducing Hilbert and inverse Hilbert transformations. A numerical simulator with Simulink and a hardware implementation with USRP and LabVIEW have been developed. Simulations and experiments reveal that even if the CIR before harmonics rejection is 0dB, the proposed receiver recovers the original sensor data with over 0.98 cross-correlation

Design And Implementation Of Multiband RFID System For Hypermarket e-Payment System

The bill creation method that applied in hypermarkets is time-consuming and customers have to wait for a long time to get their bill. This research focuses on finding a solution to reduce the waiting time at bill counter using embedded multiband RFID technology. Passive RFID technology and ZigBee wireless module characteristics were studied and multiband RFID system (EPARFID) system was developed to be used to obtain experimental data to analyze WSN performance and RFID characteristics. The EPARFID system was embedded with two mechanisms which are the 915 MHz RFID passive system and 2.45 GHz ZigBee based active RFID. The EPARFID system performance was tested and compared with the standalone ZigBee module by focusing on common performance indicators such as Communication range, Throughput Evaluation, Latency, Self-Healing and Data Collision. Set of RFID characteristics experiments have been performed in this research and some essential characteristics of RFID technology are successfully found. It was found that the optimum distance between tag and reader is 0.7 m for LOS and 0.3 m for NLOS. Based on the investigation, it is successfully validated that RFID technology does not need LOS in detecting the passive tags. It also found that the relative dielectric permittivity of the materials that being used in the experiment is giving significant effects on EPARFID performance. Materials with lower relative permittivity show consistence performances compared to materials with higher relative permittivity. A combination of experimental data with analytical EM models improves the extrapolation of RFID read-rates in a given environment. The model approach is a step towards developing a robust methodology to predict RFID read-rates on complex set of materials or standard packaging materials (SPM). The results obtained from the proposed prediction modeling of read rate based on the Friis free space equation through a quantification of uncertainties provides new insights on the nature of tag read rates. Furthermore, the confirmation of the closeness of the proposed model approach with the EPARFID system experimental data establishes the validity of the proposed modeling approach

Goodbye, ALOHA!

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The vision of the Internet of Things (IoT) to interconnect and Internet-connect everyday people, objects, and machines poses new challenges in the design of wireless communication networks. The design of medium access control (MAC) protocols has been traditionally an intense area of research due to their high impact on the overall performance of wireless communications. The majority of research activities in this field deal with different variations of protocols somehow based on ALOHA, either with or without listen before talk, i.e., carrier sensing multiple access. These protocols operate well under low traffic loads and low number of simultaneous devices. However, they suffer from congestion as the traffic load and the number of devices increase. For this reason, unless revisited, the MAC layer can become a bottleneck for the success of the IoT. In this paper, we provide an overview of the existing MAC solutions for the IoT, describing current limitations and envisioned challenges for the near future. Motivated by those, we identify a family of simple algorithms based on distributed queueing (DQ), which can operate for an infinite number of devices generating any traffic load and pattern. A description of the DQ mechanism is provided and most relevant existing studies of DQ applied in different scenarios are described in this paper. In addition, we provide a novel performance evaluation of DQ when applied for the IoT. Finally, a description of the very first demo of DQ for its use in the IoT is also included in this paper.Peer ReviewedPostprint (author's final draft

An RFID Anti-Collision Algorithm Assisted by Multi-Packet Reception and Retransmission Diversity

RFID provides a way to connect the real world to the virtual world. An RFID tag can link a physical entity like a location, an object, a plant, an animal, or a human being to its avatar which belongs to a global information system. For instance, let's consider the case of an RFID tag attached to a tree. The tree is the physical entity. Its avatar can contain the type of the tree, the size of its trunk, and the list of actions a gardener took on it

AnonPri: A Secure Anonymous Private Authentication Protocol for RFID Systems

Privacy preservation in RFID systems is a very important issue in modern day world. Privacy activists have been worried about the invasion of user privacy while using various RFID systems and services. Hence, significant efforts have been made to design RFID systems that preserve users\u27 privacy. Majority of the privacy preserving protocols for RFID systems require the reader to search all tags in the system in order to identify a single RFID tag which not efficient for large scale systems. In order to achieve high-speed authentication in large-scale RFID systems, researchers propose tree-based approaches, in which any pair of tags share a number of key components. Another technique is to perform group-based authentication that improves the tradeoff between scalability and privacy by dividing the tags into a number of groups. This novel authentication scheme ensures privacy of the tags. However, the level of privacy provided by the scheme decreases as more and more tags are compromised. To address this issue, in this paper, we propose a group based anonymous private authentication protocol (AnonPri) that provides higher level of privacy than the above mentioned group based scheme and achieves better efficiency (in terms of providing privacy) than the approaches that prompt the reader to perform an exhaustive search. Our protocol guarantees that the adversary cannot link the tag responses even if she can learn the identifier of the tags. Our evaluation results demonstrates that the level of privacy provided by AnonPri is higher than that of the group based authentication technique