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Interactive Systems Technical Design

Interactive Systems Technical Design. Lecture #2 Wireless ad hoc networking for mobile peer-to-peer communications. Wireless Ad Hoc Networking. Webster: ad hoc ~ “formed or used for specific or immediate problems or needs“ ” fashioned from whatever is immediately available”

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Interactive Systems Technical Design

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  1. Interactive Systems Technical Design Lecture #2 Wireless ad hoc networking formobile peer-to-peer communications ISTD 2003

  2. Wireless Ad Hoc Networking • Webster: ad hoc ~ • “formed or used for specific or immediate problems or needs“ • ”fashioned from whatever is immediately available” • No fixed/static network infrastructure • Nodes provide network functionality ISTD 2003

  3. Mobility • stationary • nomadic (pedestrian speed) • mobile (vehicular speed) • roaming (mobile across networks) • Connectivity • connected • semi-connected • (asymmetric) • weakly connected • disconnected • Mobile device capability • form factor • GUI • multimedia • real-time multimedia Variability of the Mobile Environment Source: Helal ISTD 2003

  4. Case Studies Hocman – Fast Motor Bikers and Ad Hoc Networking Mobility Studio, Interactive Institute, Sweden Hummingbird – Inter-Personal Awareness Device Play Studio, Interactive Institute, Sweden ISTD 2003

  5. The Hocman Prototype Fast Motor Bikers and Ad Hoc Networking Mattias Esbjörnsson Oskar Juhlin Mattias Östergren INTERACTIVE INSTITUTE Best Paper Award1st Int. Conf. Mobile and Ubiquitous Multimedia (MUM 2002)Oulu, Finland, Dec 2002http://www.mum2002.oulu.fi ISTD 2003

  6. BikeTalk Project • Ethnographic fieldwork • Design requirements • The Hocman prototype • Architectural design • Implementation • Evaluation • Performance evaluation • User evaluation ISTD 2003

  7. Ethnographic Fieldwork • User-centered and contextual design • Identification of motor biker’s activities • Leisure • Social • Visual • Interaction occurs • Opportunistic encounters • Because it is organized • Co-movement • Place-centered movement • Design requirements ISTD 2003

  8. Motor Bikers’ Activities Illustrated ISTD 2003

  9. Design Requirements • Added value: augment rather than rationalize • Social interaction: sustain encounters • Identification: better means to get to know others • Heterogeneous user groups: biker culture is diverse • Invitation for joint rides: selecting participants from previous encounters • Simultaneous activities: user attention varies ISTD 2003

  10. Architectural Design Principles • Handheld mobile device • Mobile context of use • Wireless ad hoc networking • No network infrastructure available! • Peer-to-peer communications • Data sharing between peers ISTD 2003

  11. Network Design • Wireless ad hoc networking • No network infrastructure available! • IEEE 802.11b IBSS • ”IP over single-hop ad hoc networking” • Requires no infrastructure ISTD 2003

  12. IEEE 802.11 Topologies Distribution System IBSSIndependent Basic Service Set Infrastructure Basic Service Set Extended Service Set ISTD 2003

  13. Wireless ad hoc networking with IEEE 802.11b IBSS Each biker is a 802.11b node IBSSIndependent Basic Service Set ISTD 2003

  14. Peer-to-peer communications • Motivation: data sharing between peers • Requires • Rapid mutual peer discovery • Data transfer between peers • Support for two modes of user attention • Cruise: automatic download and logging while driving • Browse: manual HTML browsing ISTD 2003

  15. Rapid Mutual Peer Discovery • Each node keeps a list of known peers • When timer for entry expires, remove it from list • Each node broadcasts a hello message at regular interval • When node A receives hello message from node B • If present(B): reset B’s timer • Else: append B and send reply(A,B) message • When C receives a reply(A,B) message • If not present(A) and (present(B) or B=C): append A ISTD 2003

  16. 1. A sends hello(A) 2. B sends reply(A, B) 3. C sends reply(A, C) A 1. A, B, C | A C 2. A, B, C | A, B 3. A, B, C | A, B, C Rapid Mutual Peer Discovery Illustrated B ISTD 2003

  17. Data Transfer Between Peers • ”Limited” HTTP 1.0 • Data • HTML pages • Embedded resources, e.g images • Retrieval method #1: Get • 1. check local cache • 2. HTTP GET w/ Keep-Alive • Retrieval method #2: Reload • HTTP GET w/ If-Modified-Since and Keep-Alive ISTD 2003

  18. Hocman architecture Operation sequence in cruise mode ISTD 2003

  19. Hocman UI (Browse Mode) reload cruise mode empty log • Browser • local pages • remote pages • Peers • current peers • reachable peers • Log • event log • encounters ISTD 2003

  20. Implementation • Mobile devices • Compaq iPAQ 3660 + Orinoco WLAN card • Sympol PPT 2700 + built-in Spectrum24 WLAN • WLAN: IEEE 802.11b IBSS • Mobile platform • Pocket PC • Programming environment • C/C++ ISTD 2003

  21. Hocman in Use ISTD 2003

  22. Data sharing Data sharing A B C C C Performance Evaluation v Peer Index page size # embedded Resource size [bytes] resources [bytes] A 1 310 2 (image, audio) 67 914 B 921 1 (image) 8 597 C 1 241 1 (image) 7 138 ISTD 2003

  23. Performance Evaluation (cont.) • Peer C drives by at three different speeds v(50 km/h, 70 km/h and 90 km/h) • Five repetitions for each speed • Log and cache is cleared for each repetition • Data sharing • Peer C downloads data from peers A and CB • Peers A and B download data from peer C • Performance criteria: number of failed downloads ISTD 2003

  24. Performance Evaluation (cont.) Number of failures of the 5 repetitions Peer Download from Data Peer C’s speed 50 70 90 page . . . A image . . 3 audio . . 4 C B page . . . image 2 . 2 ISTD 2003

  25. Performance Evaluation (cont.) Number of failures of the 5 repetitions Peer Download from Data Peer C’s speed 50 70 90 A C page . . . image . . 1 B C page . . . image . . . ISTD 2003

  26. Performance Evaluation (cont.) Cumulative percentage of failures of all downloads Peer C’s speed Data 50 70 90 page . . . image 10 . 30 audio . . 80 ISTD 2003

  27. User Evaluation • Specific route • Hocman in cruise mode • Two groups of three bikers • Monitoring of actions after the ride • Interviews • Results not yet available … ISTD 2003

  28. Conclusion : Hocman Meets Requirements • Added value: awareness of encounters, information sharing • Social interaction: logs encounters, images, audio clips • Identification: icons, downloaded pages • Heterogeneous user groups: HTML is flexible • Invitation for joint rides: phone numbers, URL’s, e-mail address • Simultaneous activities: automatic background downloads, HTML browser ISTD 2003

  29. More Information • http://www.tii.se/mobility/Biketalk/index.htm • Publicly available • Source code • Binaries for ARM and MIPS ISTD 2003

  30. Hummingbird Inter-Personal Awareness Device Lars-Erik Holmquist Jennica Falk Joakim Wigström INTERACTIVE INSTITUTE Journal of Personal Technologies, 1999 http://www.playresearch.com/ ISTD 2003

  31. IPAD (Inter-Personal Awareness Device) • Contact facilitator, not mediator • Helps to initiate a contact, but not necessarily maintain it • Identified properties • Inter: IPAD utilizes relationship between itself and other IPAD’s • Personal: IPAD is personal, carried all times • Awareness: IPAD conveys awareness of others • Device: IPAD is a self-sufficient device, not reliant on any infrastructure (e.g. network) except that provided by other IPAD’s ISTD 2003

  32. Simple Principles of Functionality • A Hummingbird does not do anything on its own • If two or more Hummingbirds belonging to the users in the same group are ”close” (<100 m) they will produce a sound – they ”hum” • Additionally, Hummingbird’s display provides the identity of the other users in the vicinity ISTD 2003

  33. Building Blocks • Microcontroller • LCD screen (2 x 8 characters) • Miniature speaker • Radio transceiver (433,92 MHz) • Rechargeable batteries (10-15 h per charge) • Two switches (hum on/off, power on/off) ISTD 2003

  34. Continous Operation of A Hummingbird • Transmitting of own identification code • Listening for the codes of other Hummingbirds possibly in the vicinity • Displaying of the codes of Hummingbirds found in the vicinity ISTD 2003

  35. User Experience and Evaluation #1 Familiar setting: home, office, school, … Key findings from a small evaluation in office setting • Hummingbird placed in the background of user’s attention • Awareness information provided by Hummingbird was useful but not ”crucial” • Possibly increased the informal interaction between users In familiar setting Hummingbird was mostly in the background of the user’s attention ISTD 2003

  36. User Experience and Evaluation #2 Unfamiliar setting: rock festival, conference, … Key findings from small evaluations in Roskilde rock festival and SIGGRAPH conference • Hummingbird promoted feeling of ”connection” • Frustration when user could not make visual connection in addition to Hummingbird’s connection • Users wanted more precise information on distance and location • Sensation of not being alone in a crowd • Natural complement to other daily activities ISTD 2003

  37. Future IPAD’s ? ISTD 2003

  38. Similar Devices and Applications • Lovegety • GroupWear • Meme Tags • Proem • Cybiko Extreme • … ISTD 2003

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