Chapter 10. Monitoring and troubleshooting

Korea University Ubiquitous LAB.

Chapter 10. Monitoring and troubleshooting

Ph.D Chang-Duk Jung


Monitoring

• Types of monitoring – Monitoring the basic status – Monitoring system behavior

• Monitoring the reader– Ping command

• Determines if reader’s network interface is functioning

– Simple Network Management Protocol(SNMP)• Status checking and other monitoring functions


Measuring system behavior

• Intrusive monitoring• Non-intrusive monitoring • Statistical analysis

– Average tag traffic volume (ATTV)– Read errors to total reads (RETR)– Read error change rates (RECR)– Actual versus predicted traffic rate (APTR)– Mean time between failure (MTBF)


Average tag traffic volume

• The equation for calculating ATTV is given by:

• Where,– t is a tag detected by a reader– N is the time interval– S is the number of instances of N you want to measure to

break the results into time periods and look for patterns– T is the number of hours– P is the time period

s

j

N

t

tp TPtNS

m0 0

)(1 ,1;

11


Read error to total reads

• The equation for RETR is given by:

• where,– m2 is the RETR

– N is the time interval– e is an error of one type or another– s is the number of instances of N you want to measure to break

the results into time periods and look for patterns– t is a tag read by the reader

N

tt

N

tt

N

tt

se

em

11

12


Read error change rates

• The equation to calculate RECR is given by:

• where,– m3 is the RECR

– N is the time interval– T is the number of hours

– m2 is the RETR

1;1

1223

T

t

NN Nmmm


Actual versus predicted traffic rate

• To calculate APTR, use this equation:

• where,– m4 is the APTR

– N is the number of time intervals in the future

– ye is the estimated time from regression equation

– ya is the actual value for reader during the time period

N

tae yy

Nm

14

1


Mean time between failure

• To calculate MTBF, use this equation:

• where,– mtbf is the MTBF– N is the time interval– l is the lifetime of the population– t is the tag detected by the reader– q is the quantity of components– f is the failure rate associated with a component

N

ttt

t

fq

lmtbf

1


Scenario

• You have installed an RFID conveyor system in a bottle factory

• To optimize the conveyor installation and to troubleshoot any problem, you need to find out:– The average volume of tags to be read in a given

interval of time. This can be determined by calculating ATTV

– The scanning and tag recognizing capabilities of the RFID system by determining the ratio of the read error and the total reads by the reader. This can be determined by calculating RETR


Scenario

Time interval Number of tags detected

1 50

2 70

3 40

4 75

5 25

6 80


Scenario

• Available information– Time period, P = 1 hour = 60 minutes – Sampling period = 10 minutes – Total number of successful reads = 700 – Total number of read errors = 500

• Courier service facility– 1000 readers– Operating over a period of 100 hours

• 10 readers fail. • Calculate MTBF

– Number of components = 1– Time period, N = 100 hours – Failure rate = 10


Link margin

• the sum of the losses and gains• Formula

• where,– P(t) is the power of the transmitter

– Tx(G) is the transmit antenna gain

– Rx(G) is the receive antenna gain

– Rx is the receive sensitivity of receiver

PathlossRGRGTtP xxx


Link margin considerations

• Polarity • Radiation pattern or propagation angle • Beamwidth • Fresnel zone • Front-to-back ratio


Attenuation

Material attenuation factor dB loss

Plasterboard wallGlass wall with metal frameCinder block wallOffice windowMetal doorMetal door in brick wall

3 dB6 dB4 dB3 dB6 dB12.4 dB


Adjusting the antenna plane

• Direction of RF emission from the antenna• Reducing multipath effects

– Transmit antennas in front of receiving antennas– Separate antennas by at least 1 ft.– Don’t point transmit and receive antennas at each other


Scenario

• A university bookstore wants you to install an RFID system in their small warehouse located behind the bookstore.

• Every day, 2 trucks arrive with a shipments of books.

• As a RFID professional, you need to install the appropriate RFID system for the bookstore.

• An important part of the task is to calculate the link margin and power budgets for the antennas.


Scenario

• The available reader and tag information: – Transmit frequency band = 13.56 MHz– Transmitter output power = 30 dBm – Reader antenna make and model = Mono-static – Receiver antenna gain = 12 dBi – Length of reader antenna cable = 10 m – Transmitter antenna gain = 12 dBi – Receiver sensitivity = 30 dBm – Number of connectors = 5 – Link distance = 10 m – Obstacle distance = 2 m – Cable loss factor = 1 dB


Diagnosing failed reads

• Identifying improperly tagged items• Checking reader functionality • Troubleshooting common antenna issues


Diagnosing system hardware failure

• Firmware upgrades • Equipment replacement procedures• Equipment incompatibility • Matching antenna gain and transmission line loss • Connector types


Electrostatic discharge

• Causes damage to an RFID device • Triboelectric series ranks various materials

according to their tendency to gain or lose electrons

• The following is an example of a triboelectric series:

– Glass - Nylon– Wool - Aluminum– Paper - Cotton– Steel - Hard rubber– nickel and copper - Saran– Polyethylene - Teflon– silicone rubber

Lose electrons

Gain electrons


Diffusion process


IC dislocation


Detuning

• Mutual inductances in the RFID tags that are in close proximity to each other

• The presence of metal and different dielectric mediums near the tag

• A shift in the resonance frequency from the operating frequency


Evaluating tag management techniques

• Tag management techniques– Voiding tags– Replacing tags– Data management systems

• Savant• ONS

• Tag data management– Unreliable data can occur because of:

• Missed reading • Unreliable reading


IC functionalities

• Grounding equipment– Ground all components of the work area, such as work

surfaces, people, and equipment, to the common point ground.– Connect the common point ground to the equipment ground

because all electrical equipment at the workstation is already connected to this ground.

• Air ionizers – Are used to control ESD generation of items that cannot

discharge to the common grounding point

• Equipment separation distance– Uninsulated ground traces

• At least a 2.2 millimeter separation

– Uninsulated electronic devices• At least a 20 millimeter separation


Troubleshooting software

• Analyzing middleware – Scalability – Security – Interoperability

• Analyzing network connectivity– Reader Network Controller (RNC)– Simple Lightweight RFID Reader Protocol (SLRRP) – RFID reader network functionality


RFID reader network functionality


Unit summary

• Explained monitoring and troubleshooting RFID system by analyzing read rates, tuning and repositioning the antennas, and diagnosing failed reads and system hardware failure

• Identified symptoms for tag failure, explained tag management techniques, and identified the causes of IC failure.

• Described middleware and network connectivity requirements


Review questions

• What is a data management system and why is it essential?

• What is the benefit of intrusive monitoring?

Documents

Chapter 10. Monitoring and troubleshooting