A study analyzed wireless tracking systems for pilgrims using various technologies like RFID, NFC, Bluetooth, Wi-Fi and GPS. RFID tags were considered but had short read ranges and interference issues. Smartphone GPS provides long-range real-time tracking but requires an app and internet. Bluetooth and Wi-Fi methods don't need internet but drain batteries. The study concluded no single method was optimal and scalability was an issue for large pilgrim numbers.

1. A Study of Wireless Technology
Based Pilgrim Tracking Systems

2. Overview
• Goals
• Motivation
• Wireless Technologies
• System Designs
• Conclusion

3. Goals
• Store Data of Pilgrims (Example: Name, Home address, Passport
Number, telephones, hotel details)
• Store Bio-metric information (finger print) Pilgrims
• Activity Log of pilgrims like: Movements, Current Location
• Send alert to control room if anyone try to escape from allocated
area.
• Device will be Small and Can be attached with wrist band.

4. Motivation
Why do track someone?

5. Lost person
Trouble for relatives and
authorities
Language problem
Children
Identifying and locating among
thousands
Motivation
A lost child [1]

6. Stampede
Overcrowding
Fire
Explosion
Leaves many dead and injured
Motivation
Sabarimala stampede
[2]

7. Medical emergency
Medical history
Blood group
Contact family members
Identifying dead
Motivation
JK floods [3]

8. Flood/earthquake
Relocating pilgrims
How many are there?
Direction of movement
Motivation
JK floods [4]

9. Wireless Technologies
Utilizing radio waves

10. Wireless Technologies
1. RFID
2. NFC
3. Wi-Fi
4. Bluetooth
5. GPS

11. RFID
Radio Frequency Identification

12. 1. Radio Frequency Identification
• Operates in radio frequency band (3kHz to 300GHz)
• Automated identification
• RFID tags for each object to identify
• Categorising RFID tags based on [6]
• Source of power
• Passive
• Semi-Passive
• Active
• Power/data transfer
• Near-field
• Far-field
Waterproof RFID Wristband
[5]

13. Based on Source of Power
Passive
• Power from RFID
reader
• No battery
• Short range
• Low cost
• Small in size
• Transmit when
read by an RFID
reader
Semi-Passive
• Battery powered
• Long range
• Costly
• Larger in size
• Transmit when read
by an RFID reader
• Battery life around 5
year
Active
• Battery powered
• Long range
• Costly
• Larger size
• Transmit
automatically and
when read by an
RFID reader
• Battery life around 5
year

14. Near-field RFID
Power transferred using magnetic
induction
Data transferred by varying
current using load modulation
Range is approximately: 𝑐/2𝜋𝑓
Used at frequency < 100 MHz
Based on Power/Data Transfer
c: speed of light
f: frequency of radio wave
Figure: Near-field power/communication mechanism [6]

15. Far-field RFID
Power transferred using
electromagnetic wave capture
Reflects received signal to transfer
data by varying antenna’s
impedance
Energy received is proportional to
1/𝑟4
Range is 3 to 6 meters
Used at UHF (Ultra High
Frequency)
Based on Power/Data Transfer
Figure: Far-field power/communication mechanism
[6]

16. Effects of RFID Frequency
Factor Lower Frequency Higher Frequency
Read range (affected by energy
contained in radio wave)
Short (in
centimeters)
Long (in meters)
Interference (from Radio
reflective materials, like
beverages, metals)
Less More
Data transfer rate Less High
Cost High Low

17. Effects of RFID Frequency
Frequency
Passive Active
Range Cost Range Cost
125-134.3 kHz Low Frequency (LF) 10 cm – 30 cm $1
13.56 MHz High Frequency
(HF)
10 cm – 1.5 m $5
865-867 MHz Ultra High
Frequency (UHF)
1 m – 15 m $0.15 50 m $20
2.45 or 5.8 GHz Microwave 3 m 30 m $25
3.1–10 GHz Ultra Wide Band NA up to 200 m $5

18. Ultra-Wideband (UWB) RFID
• Operates in 3.1 – 10 GHz band
• Low power signals on a large range of frequencies instead of a
strong signal on a particular frequency
• Energy efficient
• Battery powered
• Long read range
• Less interference
• Cheaper than Active UHF RFID tags

19. 2. Near Field Communication (NFC)
• Available on high-end smartphones
• Operating frequency: 13.56 MHz
• Data transfer rate: 30 to 60 kbps
• Compatible with High Frequency RFID tags
• Can read/write HF RFID tags
• Short range
• Theoretical: 20 cm
• Practical: 5cm
• Large amount of data can be transferred by paring up Bluetooth or Wi-
Fi
• NFC chip can be read even if device is switched off
Figure: Two NFC devices
[7]

20. Wi-Fi
Getting MAC Address

21. 3. Wi-Fi
• Operates in 2.4GHz and 5GHz bands.
• Long range (20m to 300m)
• High data transfer rate
• Tracking smartphones using Wi-Fi
• Periodic transmission of probe messages
• Each frame contains MAC address in plain-text
• Techniques
• Passive
• Active

22. Passive Wi-Fi Tracking
• No transmission of frames by Wi-Fi monitor
• Silently listen to all the frames transmitted by others
• Problems
• No control over the transmission time of frames
• No guarantee of frame transmission
• A corrupted frame might be dropped
• More number of frames can provide better accuracy

23. Active Wi-Fi Tracking
• Transmission of frames by Wi-Fi monitor to trick smartphone
• Goal is to increase the
• Number of devices detected
• Number of frames transmitted
• Techniques
• Advertising popular access point’s SSID
• Opportunistic access point emulation
• Sending RTS packets

24. Advertising Popular Access Point’s SSID
• Smartphones automatically try to connect to known AP
• Broadcast beacons containing SSID of popular AP
• E.g. “attwifi”, “tmobile”
• No need of fully functional AP
• Get more frames
• Emulate fully functional AP
• Null frames for notifying power state

25. Opportunistic Access Point Emulation
• Directed probe request for known networks
• Contains SSID of the access point, along with other parameters
• Emulate access point with that SSID
• Security protocol must match for secured networks
• Security protocol information is not available in probe request
Search
• Probe
request for
SSID “A”
Emulate
• Emulate AP
with SSID “A”
Associate
• Association
request for
SSID “A”
Wait
• Null frames
transmission

26. Opportunistic Access Point Emulation
• Emulate multiple security protocols
• 4-way handshake required for secure
protocols
• Requires credentials
• No need to complete handshake
• Null frames transmitted until we
complete handshake for around 10
seconds
• After that the process is repeated

27. Emulating Access Point [8]

28. Sending RTS Frames to Known Devices
• No emulation of access points
• Transmit RTS (request to send) frame to a
device
• In response we get CTS (clear to send) frame
• CTS doesn’t have transmitter address (TA), only
receiver address (RA)
• Set TA to a unique address (UA) in each RTS
RTS
(UA,
RA)
CTS
(UA)

29. Bluetooth
Getting MAC Address

30. 4. Bluetooth
• Operates in 2.4 GHz band
• Energy efficient (2.5 mW for class 2 devices)
• Long range (10m to 30m)
• Decent data transfer speed
• Tracking methods
• Inquiry based
• Inquiry free

31. Inquiry Based Tracking
• Transmit discovery packet on predefined 32 channels
• Discoverable devices respond to this packet
• Response follows a random delay to minimize collisions
• Takes around 10 seconds for all devices to respond
• Problems
• Requires a device to be discoverable
• Privacy risk
• Disrupts normal communication whilst scanning a channel

32. Inquiry Free Tracking
• Connection based approach
• Requires paring up with Bluetooth monitor
• Send inquiry targeted for a particular device
• Requires multiple inquiry messages
• Faster targeted discovery
• Maximum 7 simultaneous connections to other devices

33. 5. Global Positioning System (GPS)
• Provides position, velocity and time
• Position accuracy (outdoor): 2 to 10 meters
• Position accuracy (indoor): > 100m
• Global Navigation Satellite System (GLONASS)
• GPS + GLONASS
• Better accuracy
• Faster fix
• Assisted GPS (A-GPS)
• Gets the almanac and ephemeris data from the Internet
• Send the location to the central server

34. System Designs
Putting all of the pieces together

35. System Designs
• Scalable
• Should handle real-time location updates of millions of people
• Reliable
• Inter-operable and compatible with other systems
• Components
• Position data collection techniques
• Location Based Services (LBS)
• Finding nearby ATM
• Traffic information
• Geographic Information System (GIS)

36. 1. Smartphone + RFID
• Developed for Hajj
• RFID tag for each pilgrim
• App for smartphones with GPS
• Locating family members or friends
• Requesting urgent help
• Map of important locations
• Control center
• Visualizing location of all pilgrims on a map
• Searching for pilgrims based on region, age etc.
• Maintains database of hospitals, location history, personal information

37. Smartphone + RFID
Figure: System architecture
[10]

38. Smartphone + RFID
• Problems
• Read range of RFID reader was low
• Affected by environmental factors
• Interference from human body
• Collocated tags
• Taking back wristband tags
• Conclusion
• Not to use wristband RFID tags

39. 2. Smartphone GPS [HajjLocator]
• Get location from GPS
• Send location using
• Wi-Fi
• 3G
• SMS (emergency)
• Update location after certain
• Time period
• Distance travelled
• Geo-fencing
• Searching for someone
• Push notifications

40. Smartphone GPS
Figure: System architecture
[12]

41. 3. Wireless Sensor Network (WSN)
• Developed for Hajj
• Need for tracking in addition to identification
• A sensor unit for each pilgrim
• Mobile sensor unit consists of
• GPS
• Microcontroller
• Antenna
• Battery
• ZigBee radio
• Fixed master units
• Get position data from mobile sensor units
• Send this data to central server by routing through other fixed units

42. Wireless Sensor Network
• Node configurations
• End nodes
• Routers
• Gateways
• Information packet
• UID number
• Latitude
• Longitude
• Time
• Searching for someone
• Routing multiple queries in parallel
• Based on previous known location
• Very high cost
• Comparable with smartphone
Figure: Node configurations [9]

43. 4. Bluetooth
• Networked host machines with Bluetooth class 2 devices
• Current position of all devices stored on central system
• Ask a host which is probably near to a device
• Frequent connection and disconnection
• Clock synchronization for faster connection time
• Distribute clock information to other hosts
• Can tolerate an error up to 10.24 seconds
• Average connection time after utilizing clock information: 0.64 seconds

44. 5. Wi-Fi Monitors
• Designed for tracking smartphones on a street for traffic flow and
congestion monitoring
• Wi-Fi monitor: standard AP with custom firmware
• MAC address + signal strength
• Monitors were 400 meters apart
• Mean error: 70m
• Problems
• A phone may pass a monitor without transmitting any frame and remain
undetected.
• Techniques for increasing frame transmission
• Stationary devices
• Maintain blacklist

45. Wi-Fi + Bluetooth
Figure: Meshlium Scanner [11]

46. Summary
Technology Distance Power
consumed
Cost Remarks
RFID
(Passive)
< 3 m No battery Very Low Best suited for identification
RFID (Active) ~ 100 m Very Low Low Interference from human body
NFC ~ 4 cm No battery High Can read/write RFID tags
Bluetooth 10 m – 30 m Low High High availability in phones
Wi-Fi 20 m – 200 m High High Drains battery of smartphone
GPS +
Networking
Anywhere on
earth surface
High Very High Requires an app to be installed in
smartphone

47. Conclusion
• Passive UHF RFID tags are cost effective but their range is limited
to 3 meters.
• UWB tags can provide long range but are more expensive.
• Using smartphone GPS is best for real-time tracking but require
active Internet connection.
• Bluetooth and Wi-Fi based methods are independent of OS of
smartphone and don’t require Internet connection.
• None of the system discussed address the issue of scalability.
• None of the methods are without drawbacks.