Optimization of Transmission Characteristics in UHF Transponder Systems

Radio Frequency IDentification (RFID) Systeme verwenden Funkwellen für die Identifizierung von Objekten. In den letzten Jahren haben sich RFID-Systeme in einen aktiven interdisziplinären Forschungsbereich entwickelt. Verschiedene Algorithmen und Techniken von anderen Kommunikationsbereichen können und sind in RFID-Systeme eingesetzt worden. Ziel dieser Arbeit ist die Optimierung und Verbesserung von UHF RFID passiven Systemen. Es wird angestrebt die Anzahl der erfolgreichen Leseversuche bei ungünstiger Umgebung zu erhöhen bzw. zu ermöglichen. Die neu entwickelten Algorithmen sollten sich den dynamischen Arbeitskonditionen anpassen.Radio Frequency IDentification (RFID) systems use radio waves in order to retrieve the identity of an object. In the last years RFID systems has evolved into an active multidisciplinary area of research and development, composed by a broad spectrum of fields. Many algorithms and technologies of other communication areas can and have been applied to RFID systems. The goal of this thesis is to optimize and improve the RFID passive systems working on the UHF frequency band. The objective is to enable or even increase the probability of a successful read in harsh environments. The new developed algorithms should adapt to the dynamic working conditions

Saiyan: Design and Implementation of a Low-power Demodulator for LoRa Backscatter Systems

The radio range of backscatter systems continues growing as new wireless communication primitives are continuously invented. Nevertheless, both the bit error rate and the packet loss rate of backscatter signals increase rapidly with the radio range, thereby necessitating the cooperation between the access point and the backscatter tags through a feedback loop. Unfortunately, the low-power nature of backscatter tags limits their ability to demodulate feedback signals from a remote access point and scales down to such circumstances. This paper presents Saiyan, an ultra-low-power demodulator for long-range LoRa backscatter systems. With Saiyan, a backscatter tag can demodulate feedback signals from a remote access point with moderate power consumption and then perform an immediate packet retransmission in the presence of packet loss. Moreover, Saiyan enables rate adaption and channel hopping-two PHY-layer operations that are important to channel efficiency yet unavailable on long-range backscatter systems. We prototype Saiyan on a two-layer PCB board and evaluate its performance in different environments. Results show that Saiyan achieves 5 gain on the demodulation range, compared with state-of-the-art systems. Our ASIC simulation shows that the power consumption of Saiyan is around 93.2 uW. Code and hardware schematics can be found at: https://github.com/ZangJac/Saiyan

Embedding and decoding hidden data channels on computer displays

In a given setup, a LCD screen is mounted horizontally so that objects, e.g. game tokens, can be placed on the surface of the display. A PC displays information on the screen, e.g. a floor plan of a board game. The object placed on the screen is equipped with one or more optical sensors that ¿look¿ at the display area under the object. The information captured by the sensor is transmitted back to the PC that displays the information (after optional pre-processing the object). In order to determine de position of the objects in the screen, the screen is partitioned into a large number of separate areas. A separate hidden data channel has to be implemented in each of these areas. The data transmitted through these data channels can be used to transmit position identifying the given area. The task of this work is to research and design a system for implementing such a multitude of hidden data channels on a video display with the following constraints: - The displayed hidden data channel shall be invisible or at least unobtrusive to the human eye in the chosen setup. - The capacity of the channel should be as large as possible. - The system should be able to function if the sensor is placed between two, or three of the hidden data channel areas. - The system needs to be robust against typical error signals like ¿strobing back light of the display¿. - The system should be able to adapt to special conditions found on different types of display families.Querol Giner, AJ. (2009). Embedding and decoding hidden data channels on computer displays. http://hdl.handle.net/10251/21015.Archivo delegad

ASK COMPATIBLE CMOS RECEIVER FOR 13.56 MHZ RFID READER

Abstract: This study concerns about a high frequency companionable receiver architecture for RFID application, which is capable of dealing with most of the previous inadequacies. In this paper, an assessment of different receiver systems is shown and a simulated design of an integrated receiver for 13.56 MHz RFID Reader is proposed for 0.18μm CMOS technology. The design is mainly composed of amplifier, detector and digitizer. The system uses fewer components then that of other CMOS based RFID receivers and consumes a power of 0.325 mWatt at 1V biasing. Synthesized Results show smaller ripple (<0.0002%) than that of existing systems. Izvleček: Prispevek obravnava novo arhitekturo visokofrekvenčnega sprejemnika za RFID aplikacijo, ki odpravlja večino prejšnjih pomanjkljivosti. V tem članku je presojamo različne sprejemne sisteme in simuliramo koncept integriranega sprejemnika za 13.56 MHz RFID čitalnik izvedenaega z 0.18μm CMOS tehnologijo. Sistem je sestavljen iz ojačevalnika, detektorja in digitalizatorja. Naprava uporablja manj komponent kot RFID sprejemnik na osnovi CMOS tehnologije ter porabi 0.325 mWatt moči pri napetosti 1V. Rezultati pokažejo manjši šum (<0.0002%) kot pri obstoječih sistemih. ASK kompatibilen CMOS UDK621.3:(53+54+621+66), ISSN0352-9045 Informacije 40(2010)1, Ljubljana Introduction Radio Frequency Identification (RFID) system has been heralded as a technology fit for the 21st century, offering variety of applications. In modern time, there has been an escalating impact on the expansion of RFID technology for the localization and the identification of objects. RFID is a broadly used technology, which employs radio signals for the identification of people or objects. Its utility is to facilitate data to be transmitted into devices, which is interpreted by an RFID reader. Among the three focal constituents of RFID, reader is one which transmits the signal and processes the received data from the tag. Processing and receiving of data is carried out by the receiver. To do this, RFID reader needs to extract the message signal from the carrier and to digitize the resulting data. Our research goal is to design 13.56 MHz compatible receiver for RFID reader. For the design of a complimentary-metal-oxide-semiconductor (CMOS) based 13.56 MHz RFID receiver, one of the basic requirements is to follow ISO/IEC 14443 standardization. According to ISO/IEC 14443 standardization, a design of an RFID receiver is proposed in this study. The carrier signal from the RFID tag will be 13.56 MHz with a subcarrier frequency of 847.5 KHz. The modulation index has to be either ASK(Amplitude Shift Keying) 10% or ASK 100%. On the other hand, low ripple, faster settling time and low power consumption are vital criterions in designing the system. So, the ultimate design challenge is to implement a receiver, which is compatible with ISO/IEC 14443 standardization, consumes less power, uses fewer components and shows low ripple. From the recent literatures, we found, there were few researches on RFID receiver for high frequency (1MHz~20MHz) RFID operation. Though, till now, there are scopes to reduce ripple in detection and improve the performance in power consumption

Ultra Low Power IEEE 802.15.4/ZIGBEE Compliant Transceiver

Low power wireless communications is the most demanding request among all wireless users. A battery life that can survive for years without being replaced, makes it realistic to implement many applications where the battery is unreachable (e.g. concrete walls) or expensive to change (e.g underground applications). IEEE 802.15.4/ZIGBEE standard is published to cover low power low cost applications, where the battery life can last for years, because of the 1% duty cycle of operation. A fully integrated 2.4GHz IEEE802.15.4 Compliant transceiver suitable for low power, low cost ZIGBEE applications is implemented. Direct conversion architecture is used in both Receiver and Transmitter, to achieve the minimum possible power and area. The chip is fabricated in a standard 0.18um CMOS technology. In the transmit mode, the transmitter chain (Modulator to PA) consumes 25mW, while in the receive mode, the iv receiver chain (LNA to Demodulator) consumes 5mW. The Integer-N Frequency Synthesizer consumes 8.5mW. Other Low power circuits are reported; A 13.56 Passive RFID tag and a low power ADC suitable for Built-In-Testing applications

Experimental Characterization of System Parameters for Ranging in IEEE 802.15.4a using Energy Detectors

The IEEE 802.15.4a standard for impulse radio ultrawide band (IR-UWB) communication systems defines a ranging scheme which relies on the measurement of the round-trip propagation time of electromagnetic pulses. Accuracy is strongly dependent on the estimation of the timeof-arrival (TOA) of the pulse that is spread in time due to multipath propagation. The major concern therefore is the proper detection of the leading edge. In this work, the ranging capabilities of the standard are analyzed for an energy detector receiver. Emphasis is put on the influence of transmitter and receiver parameters, which are evaluated for a set of measured scenarios. It is shown that sub-meter ranging accuracy can be achieved with fixed parameter settings