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dc.contributor.authorGriffin, Joshua Daviden_US
dc.date.accessioned2009-06-08T18:43:17Z
dc.date.available2009-06-08T18:43:17Z
dc.date.issued2009-03-02en_US
dc.identifier.urihttp://hdl.handle.net/1853/28087
dc.description.abstractBackscatter radio - the broad class of systems that communicate using scattered electromagnetic waves - is the driving technology behind many compelling applications such as radio frequency identification (RFID) tags and passive sensors. These systems can be used in many ways including article tracking, position location, passive temperature sensors, passive data storage, and in many other systems which require information exchange between an interrogator and a small, low-cost transponder with little-to-no transponder power consumption. Although backscatter radio is maturing, such systems have limited communication range and reliability caused, in part, by multipath fading. The research presented in this dissertation investigates how multipath fading can be reduced using multiple antennas at the interrogator transmitter, interrogator receiver, and on the transponder, or RF tag. First, two link budgets for backscatter radio are presented and fading effects demonstrated through a realistic, 915 MHz, RFID-portal example. Each term in the link budget is explained and used to illuminate the propagation and high-frequency effects that influence RF tag operation. Second, analytic envelope distributions for the M x L x N, dyadic backscatter channel - the general channel in which a backscatter system with M transmitter, L RF tag, and N receiver antennas operates - are derived. The distributions show that multipath fading can be reduced using multiple-antenna RF tags and by using separate transmitter and receiver antenna arrays at the interrogator. These results are verified by fading measurements of the M x L x N, dyadic backscatter channel at 5.8 GHz - the center of the 5725-5850 MHz unlicensed industrial, scientific, and medical (ISM) frequency band that offers reduced antenna size, increased antenna gain, and, in some cases, reduced object attachment losses compared to the commonly used 902-928 MHz ISM band. Measurements were taken with a custom backscatter testbed and details of its design are provided. In the end, this dissertation presents both theory and measurements that demonstrate multipath fading reductions for backscatter-radio systems that use multiple antennas.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectBackscatter radioen_US
dc.subjectRadio frequency identificationen_US
dc.subjectRFIDen_US
dc.subjectFading channelsen_US
dc.subjectProbabilityen_US
dc.subjectMultipath channelsen_US
dc.subjectRayleigh channelsen_US
dc.subjectMicrowave propagationen_US
dc.subjectBackpropagationen_US
dc.subjectMicrowave radio propagationen_US
dc.subject.lcshAntennas (Electronics)
dc.subject.lcshBackscattering
dc.subject.lcshRadio frequency identification systems
dc.titleHigh-frequency modulated-backscatter communication using multiple antennasen_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentElectrical and Computer Engineeringen_US
dc.description.advisorCommittee Chair: Durgin, Gregory; Committee Member: Ingram, Mary Ann; Committee Member: Nikitin, Pavel; Committee Member: Peterson, Andrew; Committee Member: Steffes, Paulen_US


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