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Bluetooth Bas ed Wireles s Internet Applications for Indoor Hot S pots : E xperience of a S ucces s ful E xperiment During CeBIT 2001 Prof. Dr. R olf Kraemer CT O les s wire AG IHP (Innovations for High Performance Microelectronics ) T echnical Univers ity Cottbus
Outline
• • • • • •
Introduction: Wireles s Internet Bluetooth Networks S ys tems Architecture CeBIT 2001 S cenario E valuation of the R es ults Conclus ions
Our credo: Wireles s Internet is more than jus t Internet acces s without wires • Wireles s Internet s ervices have to s upport mobile pers ons or mobile objects in all as pects that res ults from mobility • Mobility might als o be interpreted as micro-mobility, i.e. s erving the res idents in their immediate environment • Individuals have to be recognized and treated according to their pers onal needs • Information and actions mus t be triggered automatically upon s pecific events • We can achieve much more than jus t cable replacement
Heterogeneity of networks IEEE802.11 IEEE802.11a IEEE802.11b
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Our Mis s ion: E nable mobile people to us e local s ervices F uture Internet: Wireles s Airport
F air
P ers onal
Indus trial F acilities
Internet Mus eum
S hopping mall
Wireles s acces s points to the Internet
P ers onalized s ervices for mobile devices
L ocal Intelligent provis ioning of local information and value added s ervices
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1 Reception of Sighting Information
5 Event Notification
2 Event Reception
6 Get and Post requests
3 Query Database
7 CGI Call
4 Sighting Indication
8 LocalNavigator primitive call
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9 Information Retrieval
T he bas ic functions s et of our s olution
Personalisation Information push („notification“) Information pull („information retrieval“) Contacting and messaging Internet access and eMail Navigation and tours Tracking and reporting
T he CeBIT 2001-project proved Bluetooth for wireles s Internet applications in Hot S pots • 130 bas es tation for 25,000 m2 • Ceiling bas ed ins tallation 18 m high • T otal power dis s ipation 130 mW – no more worries about electro-s mog • F ully managed s ys tem with wide range of s calability • Up to 200 clients could be s upported concurrently • S everal s ervices for navigation, information pus h and information broadcas t • Acces s to full CeBIT catalogue • Pocket PC bas ed
Guiding S ervice
Bluetooth Bas e S tations with es pecially des igned antennas were us ed for coverage -70 dBm Line
- 76 dBm
-82 dBm
Directed Antennas for Coverage 16 dBm gain
T echnical R ealization of CeBIT LocalNavigator Hall 13: Hardware View
T echnical R ealization of CeBIT LocalNavigator Hall 13: Bas es tation View
T echnical R ealization of CeBIT LocalNavigator Hall 13: S erver View
Location Manager Algorithm Object seen by access points after synchronized inquiry
Calculation of visibility area Calculation of center of gravity Association of Object with closest access point
E valuation of the R es ults
1
• T he radio environment worked properly, and we had no white s pots in the hall • PE R values were meas ured between 1% and 5% . T he 5% values were determined when many other 2.4 GHz networks were active • T ypically, the res pons e time from s erver reques ts were between 10-100 ms • T he handover and location management algorithms worked very well – granularity of 10-20 m can be us ed for s everal location-aware applications including the CeBIT 2001 fairguide
• T he navigation s ervice always worked correctly and always res ulted in the clos es t path to the des ired booth • All s ervices were appreciated by the vis itors
E valuation of the R es ults
2
• T he reconnect time after handover was far too long. – We meas ured up to 5 s due to the relatively complex enquiry mechanis m of the Bluetooth radio
• Mis s ing client-s ide T CP/IP driver led to another problem: – A s ingle mis s ing R F COM packet caus ed the los s of a full T CP/IP mes s age
– A timeout-bas ed protocol for reques ting a retrans mis s ion caus ed increas ed waiting time for the us er • F aults in the bas eband s oftware of the Bluetooth modules caus ed s ome s ys tem cras hes – We were unable to totally avoid thes e cras h s ituations during CeBIT , but with the proper s election of s ome s ys tem parameters , we reduced them to the point where the s ys tem was working mos t of the time
Conclus ions • We were able to s how a location aware wireles s Internet s ys tem under very hars h conditions • T he location-aware s ervices were greatly appreciated by the cus tomers • We were als o able to s how that Bluetooth networks of a s ignificant s ize can be built and operated • Low power dis s ipation of Bluetooth s ys tems is the main factor for it being embedded in all terminal clas s es s uch as cell phones and PDAs • In conclus ion, we believe the experiment was s ucces s ful and that the pos itive res ults predict a great future for location-bas ed s ervices in general and Bluetooth bas ed location-aware s ervices for low-power devices in particular.
