Download presentation
Presentation is loading. Please wait.
Published byAshley Greer Modified over 9 years ago
1
1 Towards Pervasive Connectivity in Mobile Computing Frank Siegemund European Microsoft Innovation Center November 2006
2
2 Outline Motivation Related Work System Architecture Implementation Application Conclusions
3
3 Motivation Most middleware assumes basic connectivity –Web Services –Jini –Corba Problematic in mobile scenarios –Mobile P2P systems –Mobile CSCW Heterogeneity –Bluetooth, WLAN, IrDA, GPRS –IPv4 vs. IPv6 –NATs and firewalls
4
4 Mobile P2P Bootstrapping problem Establish connectivity between mobile users Mobile devices as first- class citizens in P2P applications Exploit knowledge about connectivity in the group More reliable/robust group establishment
5
5 Scenario Content sharing between mobile users Conference scenario Skiing trip Existing group collects connectivity parameters Sharing by means of visual tags/glyphs Handheld-embedded cameras for capturing tags
6
6 Outline Motivation Related Work System Architecture Implementation Application Conclusions
7
7 Related Work Capturing visual tags with handheld devices and low-cost cameras –Rekimoto et al. Visual tags in Pervasive Computing –Rohs and Zweifel –Many interesting scenarios Visual tags to bypass Bluetooth device discovery –Scott et al.
8
8 Related Approaches Out-of-band discovery for Bluetooth –IrDA –RFID Collaborative approaches for device discovery –Siegemund and Rohs Manual configuration Send SMS with information about group –Complicated from user perspective
9
9 Outline Motivation Related Work System Architecture Implementation Application Conclusions
10
10 System Architecture
11
11 Collecting Connectivity Data Overlay between group members Exploit heterogeneity –Various communication technologies in group –Different security constraints Construct group connectivity profile Create tags to transmit connectivity profile Candidate group member captures tags Simplified user interaction
12
12 Group Overlay Overlay can contain both mobile and stationary nodes Overlay provides multicast group Nodes in group have synchronized state Connectivity properties of nodes shared between group members NATs can be dealt with via different group peers Direct connections not always possible Group used to circumvent connectivity constraints
13
13 Visual Tags Tags captured from video stream Captured by handheld- embedded digital cameras Direct user feedback about detected tags possible Small video resolution requires displaying multiple tags Concrete tag layout unimportant
14
14 Outline Motivation Related Work System Architecture Implementation Application Conclusions
15
15 Implemenation Heterogeneous environment –Windows Mobile 5.0 smartphones –Window XP/Vista desktops Implementation on desktops using Windows P2P Infrastructure Mobile devices join/create P2P overlay –Socket interface –Lightweight database for data synchronization Native implementation
16
16 Visual Tags Tag detection in DirectShow Analyze single video frames Basic algorithm –Black and white conversion –Region detection –Identify guide bars –Decode tags –Determine tag index –Finish if all tags have been decoded –Join group Similar to Rekimoto et al.
17
17 Improvements Determine threshhold for black/white conversion in feedback loop –Different lightning conditions Mark tag in video frame to provide feedback to users –Tag detected or not Synchronization –Tag contains time a single tag is displayed –Capturing device can calculate schedule for reading tags
18
18 Evaluation 240 x 320 video frame resolution Implementation on 195 Mhz smartphone –State of the art (no high-end model) 400 ms per frame –Can be improved significantly !!! –Copy filter 90 ms for thresholding 250 ms for region detection Algorithm deals with small rotations of the tag More sophisticated tag detection systems available
19
19 Outline Motivation Related Work System Architecture Implementation Application Conclusions
20
20 Example Application Mobile P2P chat application Messaging for user groups on mobile devices Overlay to distribute connectivity parameters Tags to exchange connectivity profiles Deal with NATs and connectivity constraints
21
21 Outline Motivation Related Work System Architecture Implementation Application Conclusions
22
22 Conclusions Basic connectivity problematic in mobile scenarios Current middleware solutions insufficiently address this problem Facilitate groups to establish connectivity in mobile scenarios Groups create finger print of network environment NATs and security constraints can be dealt with Visual tags user friendly way to communicate connection properties Useful for mobile P2P and CSCW scenarios Real-life applications
23
23 Contact Frank Siegemund European Microsoft Innovation Center Ritterstrasse 23, 52072 Aachen franksie@microsoft.com
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.