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The Active Badge Location System

R. Want, A. Hopper, V. Falcao, and J. Gibbon

in ACM Trans. on Information Systems, Vol. 10, No. 1, Jan. 1992, pp. 91-102

-- presented by Yu-Chee Tseng --

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How Do We Locate People?

Goal: efficient location and coordination of staff in a large organization.Ex: location of doctors, staffs, and patients in a hospital.

Existing Solutions:broadcastinga phone to call several possible numbersa beeper with audible signal or call-back numberkey card (刷卡驗證 ) for access control:

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Active Badge System

each badge that can automatically emit a unique code a network of sensors placed around the building a master server, also connected to the network, makes the

location information available to outside world

Active Badge

Active Badge

...Active Badge

Badge Sensor

Badge Sensor

Server/Applicationnetwork

wirelessIR

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Active Badge Design (cont.)

Pulse-width modulated infrared (IR) signaling: transmission range: 6 meterscan reflect by office partitions, but will not penetrate like

radio signals emits a unique code every 15 sec, for about 1/10 sec.

Quite power-saving. Can last for > 1 year.Has a light detector. On dark (e.g., badge placed in a

drawer), increase emitting period. Can last for > 4 years. Good performance to wear on breast pocket; OK to wear

on belt or waist.

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Badge Sensor and Networking

many sensors can be installed, as the unit cost is very low.can be placed on walls, entrances, exits, corridors, public

areas, etc. sensor ---(RS232)---> computer ---(Ethernet)--> server

up to 128 sensors can be supported by a computera FIFO buffer can store 20 badge data items (to avoid

network congestion) sensor networking:

4 wires (2 for power supply, 1for control/poll, and 1 for data)

conform to telephone cabling, thus easy for cabling and low-cost

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Badge Sensor and Networking (cont.)

fig. 2

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Application: Active Office

a system integratingnamelocation informationphone network

commands supported:FIND (name)WITH (name): who are the other badges nearby name nowLOOK (location)NOTIFY (name)HISTORY (name)

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Active Office Display Screen

Fig. 3

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Benefits of Active Office

automatic re-direction of incoming callsrelieve burden of receptionistyou have less chance of missing some important calls you

are waiting for receptionist can easily tell whether a person is in or not easier when calling for a meeting easy to identify visitors to our organization

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Conclusions

Future: extend to 2-way communication

Future: combine with motion detectorcan provide high securityif a person moves without active badge being detected, an

alarm can be alerted. Mobile 911 (emergency call)