Dynamic Object Tracking in Wireless Sensor Networks Tzung-Shi Chen 1, Wen-Hwa Liao 2, Ming-De Huang 3, and Hua-Wen Tsai 4 1 National University of Tainan, Dept. Information and Learning Technology 2 Tatung University, Dept. Information Management 3 Chang Jung Christian University, Dept. Information Management 4 National Cheng-Kung University, Dept. CSIE Wang, Sheng-Shih Dec. 26, 2005 IEEE International Conference on Networks (ICON 2005)

Outline Introduction Movement Object Tracking Simulation Conclusion

Introduction Motivations  Target tracking is an important issue in WSNs Enemy vehicle tracking, habitat monitoring, etc  Cooperation of multiple sensors Objectives  Mobile object tracking Accurate Quick Energy efficiency

Movement Object Tracking --- Overview A F1 F3 F6 F7 F10 F2 F11 F12 F13 source mobile target ingress node sensor

Movement Object Tracking --- Operation Target discovery Mobile target detection Target tracking Track improvement  Face track adjustment  Loop face track adjustment

Target Discovery Target enters the network

Target Discovery (cont’d) Three sensor nodes detect the target

Target Discovery (cont’d) Where ? Three sensor nodes build their corresponding faces

Target Discovery (cont’d) query packet Source sends a query packet to discover the target

Target Discovery (cont’d) reply packet state  active active time  infinite Ingress node The sensor closest to the target replies the packet to the source

Target Discovery (cont’d)

Mobile Target Detection wakeup Wakeup packet ingress id (node A) face hop count (1) A B Node A is the 1st ingress node wakeup

Mobile Target Detection (cont’d) wakeup Wakeup packet ingress id (node A) face hop count (1) A B Node A is the 1st ingress node wakeup

Mobile Target Detection (cont’d) A B Target may enter face F0, F2, or F5 F2 F5 F0 F1

Mobile Target Detection (cont’d) A B Node B sends the wakeup packets to all of its neighboring face nodes (F1, F2, F3, F4, and F5)  Node A knows that node B is the next ingress node F2 F3 F4 F1 F0 F5 Node B is the 2nd ingress node

Mobile Target Detection (cont’d) A B F2 F3 F4 F1 active time expires  go to sleep F0 F5

Target Tracking A B C D Node A knows the next ingress node (node B) Node B knows the next ingress node (node C) Node C knows the next ingress node (node D) Source knows the 1st ingress node (node A)

Face Track Adjustment A

Face Track Adjustment (cont’d) A G B C D E F Track : (F1, F2, F3, F6, F7, F8, F9) Face hop count = 7 Not optimal track F1 F2 F3 F4 F5 F6 F7 F8 F9

Face Track Adjustment (cont’d) A G B C Optimal track : F1 F3 F4 F5 F6 F7 F8 F9 F D E F2

Face Track Adjustment (cont’d) A G B C F1 F3 F4 F5 F6 F7 F8 F9 if (face hop count = k) then send infoadj packet to the last checkface (node A) F D E F2

Face Track Adjustment (cont’d) A G B C F1 F3 F4 F5 F6 F7 F8 F9 F D E F2

Face Track Adjustment (cont’d) A G B C F1 F3 F4 F5 F6 F7 F8 F9 F D E The ingress nodes, B, C, D, and E, are canceled F2

Face Track Adjustment (cont’d) A G B C Node A finds the next ingress node closest to the kth ingress node (F), and then sends an adjustment packet to the next ingress node F1 F3 F4 F5 F6 F7 F8 F9 F D E adjustment F2

Loop Face Track Adjustment A G B C F1 F3 F4 F5 F6 F7 F8 F9 D E F2 F H

Loop Face Track Adjustment (cont’d) A G B C F1 F3 F4 F5 F6 F7 F8 F9 D E F2 Track : (F1, F2, F3, F6, F7, F8, F9, F4, F3) F H loop

Loop Face Track Adjustment (cont’d) A H B C F1 F3 F4 F5 F6 F7 F8 F9 F D E F2 Node C receives the wakeup packet from node H and detects the loop,  node C sends a deletion packet to node H deletion G

Loop Face Track Adjustment (cont’d) A G B C F1 F3 F4 F5 F6 F7 F8 F9 D E F2 F H

Simulation Model ns-2 simulator Sensing field: 500 m  500 m 1000 sensor nodes (random deployment) Communication range = sensing range = 25 m Power  Tx = Rx = 175 mW  Initial: 5 joule Moving speed  Target: 20 m/s  Source: 10 m/s, 20 m/s, or 30 m/s Simulation time: 2000 secs

Simulation --- Comparison Threshold Flooding (TF)  When the source reaches the location of the target, target discovery process is executed again Schedule Flooding (SF)  The source executes the target discovery process every 2 secs Schedule Updating (SU)  The source queries once  The sensor which detects the target sends the update message to the source every 2 secs Proposed Object Tracking scheme (OT)

Simulation Result --- First Catching Time infrequent query flooding and face track adjustment

Simulation Result --- Energy Consumption before the first catch after the first catch flooding-based less query flooding

Simulation Result --- Lifetime query packet is required although the source is near the target

Conclusion Target tracking protocol  Dynamic  Energy efficiency  Shorter tracking path  Loop avoidance

Movement Object Tracking --- Overview Flooding method The track of the target is recorded in a set of ingress nodes

Movement Object Tracking --- Idea The activated sensor nodes detect the tracked object and keep the information of track for the source The source follows the tracking route to approach the sensor node that covers the tracked object Face-aware routing  RHR is used to find the neighboring face node

Target Discovery Source issues a query packet and uses the flooding method to seek the target  (packet type, source id, target id, target location) A sensor closest to the target sends a reply packet to the source  State: active; active time: infinite  Ingress node Only one sensor in a face will send the reply packet

Mobile Target Detection --- Concept Every active node detects the target and checks whether it is closest to the target The sensor closest to the target forwards the wakeup packet All neighboring face nodes keep the information of the target, and then enters the sleep state when the active time expires Wakeup packet  (packet id, ingress node, sender id, face id, target location, active time, face hop count)

Mobile Target Detection --- Example

Target Tracking --- Concept A source S knows the location of target/first ingress node after a target discovery process, and then it begins to move towards the location of first ingress node (checkface) When it reaches the location, the first ingress sensor informs it about whether the target is still in here or not. If yes, the source catches the target o. If no, the sensor informs the source the location of next ingress node. Then, the source moves towards the location of next ingress node again. The first ingress node also informs the next ingress node the source will arrive in your location. The next ingress becomes the first ingress node (checkface)

Target Tracking --- Example Source moves to the 1st ingress node

Face Track Adjustment --- Overview

Face Track Adjustment --- Example

Face Track Adjustment --- Checkface

Loop Face Track Adjustment

Simulation Result --- Failed Sensor Ratio Failed sensor ratio represents the ratio of sensor consumed