Path Loss Propagation And Interference Mitigation In UHF-RFID Systems

Large scale path loss modeling plays a fundamental role in designing both fixed andmobile radio systems. Wireless system are complex systems, so that prediction of the radiocoverage is not done in a exact manner. Therefore before setting the system we need tochoose a proper model of predicting path loss and interference. These proper methods dependupon the system environment, desire radio coverage and system frequency. In this thesis ofpredicting path loss and interference analysis of UHF-RFID, we try to eliminate three majorproblems associated to RFID systems.(1) In the first phase of the thesis we discuss the detail about the GSM frequency effecton RFID read result. Our main concern is on the effect of GSM mobile phone on the UHFRFID read results. A test bed simulation is performed to analyze the compatibility of twotechnologies. We assume RFID frequency at868MHz while GSM frequency at880.5MHz.The nature of the interference can be noted on Spectrum Analyzer along with a developmentof Okumura Hata Model in Matlab R20121. The reason to use the Okumura Hata Model forthis experiment is the suitability of frequency ranges and distance covered by the interrogatorand transponder.(2) In the second part of the paper we discuss UHF-RFID interference and path lossmodel. The reader collision problem and tag collision problem make RFID system evenunstable. By analyzing of the existing techniques of collision avidness along with theirworking principle. For the testing purpose two RFID tag with one reader to analyze theinterference between tags upon reader response.2.45GHz adjustable tags are used for entireexperiment. Furthermore we describe a new protocol named AFSA (Accelerated frame slottedAloha) that shows a better result performance as compare to other in the system. A Matlabcode is used to simulate the performance of our proposed solution。(3) Path loss theory and experiment of UHF RFID system is also a major considerationof this study. At first all existing approaches for path loss modeling are discussed with theircommon properties and characteristics. We are using2.45GHz dense reader to calculate pathloss modeling for UHF RFID. In our entire experiment we choose ITU model due to theirfrequency complexity. Performed experiment shows that a signal loss have a maximum effecton read result and also harm the system. At the end we derived a Matlab code to visualize theimpact of RF path loss on UHF read results.