A Study of Wireless Technology Based Pilgrim Tracking Systems

Overview

• Goals

• Motivation

• Wireless Technologies

• System Designs

• Conclusion

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.

MotivationWhy do track someone?

Lost personTrouble for relatives and authorities

Language problem

Children

Identifying and locating among thousands

Motivation

A lost child [1]

StampedeOvercrowding

Fire

Explosion

Leaves many dead and injured

Motivation

Sabarimala stampede [2]

Medical emergencyMedical history

Blood group

Contact family members

Identifying dead

Motivation

JK floods [3]

Flood/earthquakeRelocating pilgrims

How many are there?

Direction of movement

Motivation

JK floods [4]

Wireless TechnologiesUtilizing radio waves

Wireless Technologies

1. RFID

2. NFC

3. Wi-Fi

4. Bluetooth

5. GPS

RFIDRadio Frequency Identification

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-fieldWaterproof RFID Wristband

[5]

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

Near-field RFIDPower 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 lightf: frequency of radio wave

Figure: Near-field power/communication mechanism [6]

Far-field RFIDPower 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]

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

Effects of RFID Frequency

FrequencyPassive 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

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

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]

Wi-FiGetting MAC Address

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

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

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

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

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

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

Emulating Access Point [8]

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)

BluetoothGetting MAC Address

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

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

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

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

System DesignsPutting all of the pieces together

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)

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

Smartphone + RFID

Figure: System architecture [10]

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

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

Smartphone GPS

Figure: System architecture [12]

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

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]

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

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

Wi-Fi + Bluetooth

Figure: Meshlium Scanner [11]

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

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.