Chapter 1 Performance of Passive UHF RFID Systems in Practice RFID Systems: Research Trends and Challenges Slides prepared by Dr. Miodrag Bolic

Study objectives Problems with RFID systems from simple to complex We will focus mainly on long-range UHF systems Understand interference, sensitivity to orientation and environment, missed tags, unwanted reads 2

Problems in RFID system Consider the following situations with increasing levels of complexity: – One stationary reader and one stationary tag – One stationary reader and multiple stationary tags – Two stationary readers and one or more stationary tags – One mobile reader and several stationary tags – Large system with several mobile and stationary readers and many tags 3

4 Problems Read ranges Read rates Tag separation Interference Deployment of large RFID systems Analysis of data Software and integration Security

Problems – stationary systems One stationary reader and one stationary tag Problems Lack of well defined reading zone physical orientation of tags nature of the object the tag is placed on the environment 5

Read range Maximum distance between the tag and the antenna where the tag can be read by the reader. Blind spot is defined as the tag is in the reading range but unable to response Affected by the following parameters of reader and tag – Reader antenna gain – Tag antenna gain – Reader output power – Appropriate data coding scheme and modulation – Environment –... 6

Sensitivity to tag orientation

Problems – stationary systems 2 One stationary reader and multiple stationary tags Problems Previously introduced non-idealities Effect of collisions among tags Sensitive to proximity of other tags 8

Problems – stationary systems 3 Multiple stationary readers and one or more stationary tags Problems Previously introduced non-idealities Reader-to-reader interference Reader-to-tag interference Unwanted reads 9

10 RECEIVING AREA STORAGE AREA DOCK 1 R R R R Reader-to-Reader Interference Zone Reader-to-Tag Interference Zone Interrogation Zone LEGEND Reader Density From: Presentation by Reva Systems

11 Interference Reader to reader Dense-Reader Mode: readers can detect weak tags amongst many strong readers Reader to tag Typical tags are not selective => Susceptible to interference – From far-away readers – On channel or in different channels From: Presentation by Reva Systems

Problems – mobile readers One mobile reader and multiple stationary tags Problems Previously introduced non-idealities Missed tags Increased level of interference 12

Problems – complex RFID systems Multiple readers and many tags Complexity issues Software integration Networking Deployment Synchronization 13

14 Analysis of information Functionality of RFID system – Capture information. – Manage information. – Analyze information. – Access information. – Act on information and events. The amount of information is overwhelming – Example: major retail chain tagged all the items. If there are 10 billion items read every 5 minutes, they will generate 15 Terabytes of data per day.

15 Security Technical security is addressed in the Gen 2 protocol – Reader does not transmit electronic product code(EPC) – Tag memory can be locked Access is password protected 32-bit access password – “Kill”command can permanently disable the Tag Protected by 32-bit kill password BUT…Security really depends on us – How much information do we want exposed? – Public policy will decide the limits

Study questions 1.How can one carry the item through the portal without being detected? 2.What is the blind spot? 3.Why don’t RFID systems work reliably? 4.If we want to make sure that tags are read and deploy multiple redundant readers, what kind of problems will we introduce? 16