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Multi-hop Passive RFID Systems

详细技术说明

This invention relates to radio frequency power transfer circuits and, more specifically, to passive tag transponder circuits of radio frequency tag-to-tag (T2T) communication systems. Current RFID (radio-frequency identification) systems are impeded by their limited interrogation range. One of the prominent reasons limiting the reader’s interrogation range is the power asymmetry, where the range of the downlink (i.e. from reader to tag) is significantly longer than the uplink (i.e. from tag to reader). Furthermore, the interference among RFID systems may restrict the number of interrogating nodes, or readers, concurrently operating in a particular location. The proposed multi-hop communication scheme for passive RFID systems allows increased reachability and concurrently-operated readers in proximal locations. These advantages facilitate the use of passive RFID tags for large-area applications previously restricted to the more costly active RFID tags. Technical Summary:    A new communication scheme is proposed to overcome the limited interrogation range of the reader. Direct T2T communications may be concatenated to form a multi-hop path between a reader and its target tag. In each of these hops, the receiving tag decodes the backscattered signal from the sending tag and forwards the information to the subsequent tag, or the reader. Such a backscattering operation, referred to as “turbo backscattering”, extends the coverage area of the reader by at least two orders of magnitude over the traditional direct reader’s interrogation scheme. Fig. 1: Turbo backscattering: tradeoff between D and r1.     A variety of interference scenarios are discussed along with proposed solutions for this new communication scheme. One such method involves a way to optimize the transmitted power waveform, as to maximize the backscattered power and separate it from the ambient radio-frequency (RF) signals. Potential interferences from the higher harmonics of the continuous wave (CW) are also eliminated when the impinging CW is modified by passing through the rectifier network.     Another implementation problem of T2T RFID systems is that a tag’s received signal backscattered from another tag can be interfered by a much stronger CW from the reader. One proposed solution involves shifting the frequency of the CW when it is backscattered by a tag, so that the received signal at the tag totally avoids the CW interference. A scheme for frequency shifting is used to achieve this, wherein the CW waveform is rectified, doubling its fundamental frequency. To optimize the conversion efficiency of the rectifier network, a particular waveform design for the CW is proposed. Fig. 2: Reachability regions used for multi-hop routing protocol. Value Proposition:    Allows the use of passive RFID tags for a coverage area over two orders of magnitude larger than currently-available passive RFID systems while reducing the required numbers of readers to interrogate a given placement of tags. Applications:Sensor Network Systems – Internet of ThingsMedical Devices – Implantable or skin-mounted tags with an external readerStructural Health Monitoring – Passive monitoring of large-scale structures for potential failureWarehouse Inventory Management – Real-time analytics of inventoryFuture Grocery Stores – Whole-cart scanning for checkoutFarming Technology- Livestock/agriculture monitoring, soil sensors, animal tags, etc. Key Benefits:Efficient – Rectified waveform maximizes backscattered power transfer with a conversion efficiency of 33%Increased Coverage - Increases coverage area by over two orders of magnitude, reduces required number of readersLow-Cost – Use of passive tags decreases cost compared to traditional RFID systems, requires less readers for same coverage Inventors:Zygmunt Haas, Ph.D. - ProfileZhong Zheng IP Status: Patent pending.Licensing Opportunity: This technology is available for exclusive or non-exclusive licensing.ID Number: MP-17003Contact: otc@utdallas.edu

*Abstract

None

*Principal Investigation

Name: Zygmunt Haas, Professor

Department: Computer Science

Name: Zhong Zheng, Post doc

Department:

国家/地区

美国