CSI5169-Indoor Localization-Zhang Zhang(7059407) (1)

CSI 5169 --- Wireless Networks and Mobile Computing

Indoor Localization

Zhang Zhangzhangzhang@uottawa.ca

Outline• Introduction

– Definition– Important parameters

• Indoor Localization Methods– Proximity Detection– Triangulation– Scene Analysis

• Indoor Localization Systems– Proximity Based– RF Based– Cameras Based

• Comparison of Common Indoor Localization Systems

Introduction - Defination

Def. Wirelessly locate objects or people inside a building in real time.

• Indoor Positioning Systems (IPS)• Real-time Locating Systems (RTLS)

Introduction - Important Parameters

• Accuracy

• Coverage

• Availability

• Update Rate

• Line of Sight (LoS) and Non Line of Sight (NLoS)

• Costs and System Complexity

Introduction - LoS / NLoS

• Line of Sight (LoS) and Non Line of Sight (NLoS)

Indoor Localization Methods / Algorithm

Methods/Algorithm

Proximity / CoO Triangulation Scene Analysis

Direction based Distance based

Angle based Time basedSignal Property

based

Proximity Detection: Sensors detect and measure reflected Infrared or visiable light or RF wave to detect the presence of an object or person in certain areas.

• Highest Received Signal Strength = Highest Probability

Methods / Algorithm - Proximity / Cell of Origan

Advantages• No complicated algorithms• Easy to implement• Low cost

Disadvantages• Low accuracy - room level• Identification problem

Methods / Algorithm - Proximity / Cell of Origan

ToA: Time of Arrival

• The precise measurement of the arrival time of a signal transmitted from a mobile device to several receiving sensors. • The distance between the mobile device and each receiving sensor can be determined.

Methods / Algorithm - Time based

Advantages• High Accuracy• 2D / 3D

Disadvantages• Precise time synchronization (1 micro-second, 300m error)• Solutions are typically challenged in environments where a large amount of multipath or interference may exist.

Methods / Algorithm - Time based - ToA

TDoA: Time Difference of Arrival

• Using relative Arrival time measurements at each receiving sensor• The synchronization between tag and each sensor is not necessary

Example: • TXC - TXA = 10-8s• TDoAC_A

• TXB - TXA = 10-7s• TDoAB_A

Methods / Algorithm - Time based - TDoA

AoA/DoA: Angle of Arrival / Direction of Arrival (DoA)

• Determining the angle of incidence at which signals arrive at the receiving sensor.

Methods / Algorithm - Angle based - AoA

Methods / Algorithm - Angle based - AoA

More sensors = Higher accuracy

Advantages• No synchronization requirement• Works well in situations with direct line of sight

Disadvantages• Susceptibility to multipath interference

Methods / Algorithm - Angle based - AoA

Signal attenuation can be exploited for distance estimation.

Methods / Algorithm - Signal Property Based

RSS: Based on the attenuation model, the Received Signal Strength can be used to estimate the distanced of a person or a mobile object.

• PR: Received signal strength at the receiver• PT: Transmitted power strength at the emitter• GT GR: Antenna gains of transmitter and receiver• d: Distance• P: The path loss factor

Methods / Algorithm - Signal Property Based

The path loss factor (P) is related to the environmental conditions P = 2 for free space P > 2 for environments with NLoS multipath P ≈ (4 - 6) for typical indoor environments

In real world application, interference, multipath propagation and presence of obstacles and people leads to a complex spatial distribution of RSS.

RSS Indicator (RSSI): averaged PR over a certain sampling period

Methods / Algorithm - Signal Property Based

Off-Line

Methods / Algorithm - Fingerprinting

Database

S1

S2

S3

...

S72

M(-35, -50, -48, -60, -58,-24) vs. Database

Methods / Algorithm - Fingerprinting

Advantages• High accuracy• NLoS

Disadvantages• Complicated algorithms• Not easy to implement• High cost

Methods / Algorithm - Fingerprinting

Indoor Localization Systems

WIFI: (a superset of IEEE 802.11 standard) can be used to estimate the location of a mobile device within this network.

Indoor Localization Systems - WIFI

WIFI

Range 50-100m

Accuracy 1m

MethodRSSI Fingerprinting ,

TDoA

NLOS/LOS NLOS

ApplicationOffice Space,

Person, Objects

RFID (Radio Frequency IDentification) system consists of readers with antennas which interrogates nearby active transceivers or passive tags.

Indoor Localization Systems - RFID

RFID Active Passive

Range 10-100m 1-5m

Accuracy 1m 0.2m

MethodRSSI Fingerprinting,

TDoAAoA, TDoA

NLOS/LOS NLOS LOS

Application Moving Objects Assembly Industry

ZigBee is a wireless technology particularly designed for applications which demand low power consumption and low data transmission.

Indoor Localization Systems - ZigBee

ZigBee

Range 20-30m

Accuracy 2m

Method RSSI

NLOS/LOS NLOS

ApplicationWarehouse

management

• Images → Cameras

• Cameras → Database

• Database → Virtual Map

Indoor Localization Systems - Cameras

Systems Accuracy Coverage Methods NLoS/LosPower

ConsumeCost Remarks

GPS 10-50mPoor

IndoorToA NLoS High High Unstable

Proximity 3-5mRoom level

Proximity LoS Low Low ID?

Cameras Networks

0.5mBuilding

levelScene Analysis LoS Low High ID?

WIFI 1mBuilding

level

RSSI Fingerprinting

/TDoANLoS High High

WIFI Covered

RFID

(Active)1m

Building level

RSSI Fingerprinting

NLoS Med MedLong 

Distance

RFID

(Passive)0.2m

Room level

TDoA/ AoA LoS Low LowNo Data

Exchange

Bluetooth 1-2mBuilding

levelRSSI

FingerprintingNLoS Low Med

High Data

Rate

ZigBee 2mBuilding

levelRSSI

FingerprintingNLoS Low Low

Low Data Rate

References

[1] Z. Farid, R. Nordin, and M. Ismail, "Recent Advances in Wireless Indoor Localization Techniques and Systems," Journal of Computer Networks and Communications, vol. 2013, 2013.

[2] R. Mautz, "Indoor positioning technologies," Habilitation Thesis, Department of Civil, Environmental and Geomatic Engineering, Institute of Geodesy and Photogrammetry, Habil. ETH Zürich, Zurich, 2012.

[3] H. Koyuncu and S. H. Yang, "A survey of indoor positioning and object locating systems," IJCSNS International Journal of Computer Science and Network Security, vol. 10, pp. 121-128, 2010.

[4] A. Aboodi andW. Tat-Chee, “Evaluation ofWiFi-based indoor (WBI) positioning algorithm,” in Proceedings of the 3rd FTRA International Conference on Mobile, Ubiquitous, and Intelligent Computing (MUSIC ’12), pp. 260–264, June 2012.

[5] S. Chan and G. Sohn, ¡°Indoor localization using Wi-Fi based fingerprinting and trilateration techiques for LBS applications,¡± in Proceedings of the 7th International Conference on 3D Geoinformation, Quebec, Canada, May 2012.

Question 1The RSSI pattern is shown below.• 3 Wifi routers• 9 refernces points

Q: Where is M(1.2, 2.6, 4.5) in this pattern?

5

2 1

3

4 1

1

4 2

5

2 1

2

3 3

1

3 3

3

1 2

1

1 3

1

2 5

1

2 3

Question 1

Q: Where is M(1.2, 2.6, 4.5) in this pattern?

A: Measured RSSI of Wifi one is 1.2. Red zone (referenced RSSI of Wifi one is 1) are possible locations.

5

2 1

3

4 1

1

4 2

5

2 1

2

3 3

1

3 3

3

1 2

1

1 3

1

2 5

1

2 3

Question 1

5

2 1

3

4 1

1

4 2

5

2 1

2

3 3

1

3 3

3

1 2

1

1 3

1

2 5

1

2 3

Q: Where is M(1.2, 2.6, 4.5) in this pattern?

A: Measured RSSI of Wifi two is 2.6. Green zone (referenced RSSI of Wifi two is 3) are possible locations.

Question 1

5

2 1

3

4 1

1

4 2

5

2 1

2

3 3

1

3 3

3

1 2

1

1 3

1

2 5

1

2 3

Q: Where is M(1.2, 2.6, 4.5) in this pattern?

A: Measured RSSI of Wifi three is 4.5. Blue zone (referenced RSSI of Wifi two is 5) are possible locations. The intersection of three zones is the location of M.

Question 2The RSSI pattern is shown above.• 3 Wifi routers• 9 refernces points

Q: Where is M(5, 2, 1) in this pattern? Is there any methods to increase the acceracy by optimizeing the system?

5

2 1

3

4 1

1

4 2

5

2 1

2

3 3

1

3 3

3

1 2

1

1 3

1

2 5

1

2 3

Question 2Q: Is there any methods to increase the acceracy of this system?

A: More Wifi routers, more reference points.

1

2

4

1

4

2 3

Question 3

A company with 3 buildings.• Building A: Working Office (Wifi coverd)• Building B: Assembly lines• Building C: Warehouse

Q: Building A: Locating persons + high rate data transmission Building B: Accurate positioning products + no data transmission Building C: Locating forklifts + low rate data transmission Which indoor localization system will you choose for Building A, Building B, Building C, respectively? why?

Question 3

A company with 3 buildings.• Building A: Working Office (Wifi coverd)• Building B: Assembly lines• Building C: Warehouse

Q: Building A: Locating persons + high rate data transmission Building B: Accurate positioning products + no data transmission Building C: Locating forklifts + low rate data transmission Which indoor localization system will you choose for Building A, Building B, Building C, respectively? why?

Answers: • A: WIFI. Wife covered, high data rate, mobile phone.• B: RFID(Passive). Small tag size, high acceracy, low cost.• C: ZigBee. Low power consumption, low cost, low data rate

Thank you!Thank you!