PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER

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PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY Development of Complex Curricula for Molecular Bionics

Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the

és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió

1 PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund *** **Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg TÁMOP /2/A/KMR

2 Peter Pazmany Catholic University Faculty of Information Technology Ad hoc Sensor Networks Érzékelő mobilhálózatok Localization algorithms and strategies for Lokalizációs algoritmusok és stratégiák vezeték nélküli hálózatok számára Dr. Oláh András TÁMOP /2/A/KMR

3 Technological motivations The role of routing Lecture 9 review Algorithmic background: the Bellman-Ford algoirthm and its distributed operation Routing in WSNs Packet forwarding in WSNs Conclusions TÁMOP /2/A/KMR

4 Motivations of localization Challenges in WSN Taxonomy of location systems Localization algorithms Accuracy requirements Available localization systems Tracking in WSN Outline TÁMOP /2/A/KMR

5 Why is localization important? It is a fundamental component for many other services GPS does not work everywhere Smart Systems devices need to know where they are Geographic routing & coverage problems People and asset tracking Need spatial reference when monitoring spatial phenomena In many WSN application we are interested in identifying the exact location: Where has something happened? Where is an Object? Determining the location of the sensor node based on other sensor nodes with known fixed locations called (beacon nodes) TÁMOP /2/A/KMR

6 Challenges in WSN Physical layer imposes measurement challenges Multipath, shadowing, sensor imperfections, changes in propagation properties (RSSI based localization) Extensive computation aspects Many formulations of localization problems, how do we solve this optimization problem? We have to solve the problem on a memory constrained processor. How do we solve the problem in a distributed manner? Networking and coordination issues We are using it for routing [ see Chapter 9], it means we have routing support to solve the problem! System Integration issues How do you build a whole system for localization? How do you integrate location services with other applications? TÁMOP /2/A/KMR

7 Real Time Location Systems The wireless devices are becoming more and more integrated into our daily lives. Wireless devices are becoming more context aware: a system is context aware if it uses contexts to provide relevant information and services (time, location, temperature, speed, orientation, biometrics, audio/video recordings, etc.) to the user, where relevancy depends on the user s tasks. Between these variables that define a context, location is probably the most important inputs that define a specific situation. Localization serves as an enabling technology (Real Time Location Systems) that makes numerous context-aware services and applications possible (Location Based Services) TÁMOP /2/A/KMR

8 Taxonomy of location systems Signaling scheme Infrared signal (inexpensive, low power; it is susceptible against sunlight; it cannot penetrate through obstructions ) Optical signal (LoS, low power, it is affected by sunlight, it provides high accuracies in the short ranges (10m)) Ultrahang jelek (high accuracies in the short range, inexpensive in LoS conditions, power hungry) Radio frequency (most commonly used, it can penetrate through obstacles and can propagate to long distances.) UWB, CDMA, OFDM, etc. Cellular systems, WLAN, WPAN, RFID, WSN Location estimation unit handset-based (self-positioning, eg.: GPS) network-based (remote-positioning, eg.: WSN) Indoor versus outdoor localization TÁMOP /2/A/KMR

9 Taxonomy of location systems (cont ) Localization type: Active Localization: system sends signals to localize target. Cooperative Localization: the target cooperates with the system. Passive Localization: system deduces location from observation of signals that are already present. Blind Localization: system deduces location of target without a priori knowledge of its characteristics. Centralized versus distributed Software-based versus hardware-based Relative coordinate versus absolute coordinate Based on performance accuracy vs. precision, calibration, cost, energy consumption, sensitivity, self organization capability, delay, datarate, etc TÁMOP /2/A/KMR

Taxonomy of location systems (cont ) Position-related parameters: received signal strength (RSS) P(d)=P 0 10nlog10(d/d 0 ) angle of arrival (AOA) r i (t)=αs(t τ i ) + n i (t) τ i d/c +(l

10 Taxonomy of location systems (cont ) Position-related parameters: received signal strength (RSS) P(d)=P 0 10nlog10(d/d 0 ) angle of arrival (AOA) r i (t)=αs(t τ i ) + n i (t) τ i d/c +(l i sin ψ)/c, ahol l i = l(n a + 1)/2 i) time-of-arrival (TOA) correlation based, synchronization is needed time difference of arrival (TDOA) TÁMOP /2/A/KMR

11 The localization algorithm Cell ID localization (the nearest reference node) Geometrical methods Triangulation (at least three nodes) Trilateration (in 2D at least three node, in 3Dat least four nodes) Multilateration Statistical methods Fingerprint based or pattern-matching TÁMOP /2/A/KMR

and leader election Fully distributed approach does not have

12 Computation models Each approach may be appropriate for a different application Centralized approaches require routing and leader election Fully distributed approach does not have this requirement TÁMOP /2/A/KMR

13 Core apps. Military Civil Accuracy requirements Applications Range Accuracy Sports tracking (NASCAR, horse races, soccer) 150m 10-30cm Cargo tracking at large depots 300m 300cm Children in large amusement parks 300m 300cm Animal tracking 300m 150cm Military training facilities 300m 30cm Military search and rescue: lost pilot, man overboard, coast guard rescue operations 300m 300cm Tracking guards and prisoners 300m 30cm Aircraft landing systems 300m 30cm Tracking firefighters and emergency responders 300m 30cm Supermarket carts 150m 30cm TÁMOP /2/A/KMR

14 Measurements technologies Available Technologies: Bluetooth, Cellular, Satellite, Television, Wi-Fi, ZigBee, Ultra Wide Band, RFID, Infrared, Ultrasound, Laser Ultrasonic ToA Common frequencies 25 40KHz, range few meters (or tens of meters), avg. case accuracy ~ 2-5 cm, lobe-shaped beam angle in most of the cases Wideband ultrasonic transducers also available, mostly in prototype phases Acoustic ToA Range tens of meters, accuracy =10cm RF ToA Ubinet UWB claims = ~ 6 inches Acoustic AoA Average accuracy = ~ 5 degrees (e.g acoustic beamformer, MIT Cricket) RSSI based localization WSN: Accuracy = 2-3 m, Range = ~ 10m : Accuracy = ~3m TÁMOP /2/A/KMR

15 Available localization systems Technology Location method Accuracy Remarks GPS ToA satellite based 1-5m Expensive, Not works indoors Ekahau (WLAN) Microsoft RADAR LOKI (WLAN) RSS-based pattern matching RSS-based pattern matching Closest AP 1m 3-4m cell size Ubisense TDOA and AOA 30cm Indoor GPS AOA 1mm No extra cost over existing wireless LAN structure, extensive utilities Scalability problems, no extra cost over existing wireless LAN structure Installed as a free software. Used for locating the closest restaurant Maximum tag-sensor distances greater than 50m Laser positioning system for indoors. Transmission range expandable from 2 to 300 m TÁMOP /2/A/KMR

16 Available localization systems: WSN Technology Location method Accuracy Remarks Active Badges Infra-red-based proximity of wearable badges to predeployed sensors Room-size Installation costs, cheap tags and sensors, sunlight and fluorescent interference, Active Bats Ultrasound ToA 9cm Ceiling sensor installation costs Cricket SpotON RSS and ultrasoundbased localization RSS-based ad-hoc localization 1m Depends on cluster size $10 beacons and receivers, installation costs $30 per tag, inaccuracy of RSS metric TÁMOP /2/A/KMR

17 Tracking in WSN Tracking mobile targets involves finding out the location of mobile targets based on wireless sensor nodes with known positions (tracing the path). Given the locations of the nodes and accurate range information to the target, it is straightforward to determine the target's position. Traditional tracking applications tend to be split into two separate phases: Localization phase: the network is localized using a specialized algorithm. Tracking phase: after localization completes, target positions are estimated based on the discovered sensor positions TÁMOP /2/A/KMR

18 Summary Location is probably the most important inputs of context aware systems. Common characteristic of numerous location system: each of them is wireless system. Network-based services that integrate a derived estimate of a mobile device s location or position with other information so as to provide added value to the user. Most location-based services will include two major actions: (1) Obtaining the location of a user, and (2) Utilizing this information to provide a service. The accuracy and precision requirements of location-based applications are highly dependent on the application characteristics. There are numerous localization technologies currently available which have different ranges, accuracy levels, costs, and complexities. Next lecture: Applications of ad hoc and sensor networks TÁMOP /2/A/KMR

PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER

PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY