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CodeBLUE : A Bluetooth Interactive Dance Club System. Farooq Anjum, Ravi Jain* Applied Research, Telcordia Technologies. Dennis Hromin, Michael Chladil, Natalie Vanatta, David Naumann, Susanne Wetzel Dept of Computer Science, Stevens Inst of Technology.
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CodeBLUE: A Bluetooth Interactive Dance Club System Farooq Anjum, Ravi Jain* Applied Research, Telcordia Technologies Dennis Hromin, Michael Chladil, Natalie Vanatta, David Naumann, Susanne Wetzel Dept of Computer Science, Stevens Inst of Technology *Current affiliation: DoCoMo USA Labs jain@docomolabs-usa.com
Outline • Motivation and Background • System design • Implementation • Lessons learned • Conclusions
Motivation • Collaborative music creation • One of the most powerful forms of human communication • Can Bluetooth be used to enable music collaboration for untrained participants? • What are the strengths and limitations of Bluetooth for such an application?
Approach • Allow participants to transform simple dance movements into musical modifications • Why Bluetooth? • Low cost • Unlicensed ISM band • Low power • Small size • Cool name …
Requirements • Unobtrusive • Small size, low weight, easily wearable • About the size of a club wristband • Rugged • Mosh pits • Long battery life to minimize maintenance • Very low cost • Ideally pennies, but dollars may be acceptable • Responsive
Original Music System design Modified Music codeBLUE DJ PC MIDI Converter Single-board Computer Light Synthesizer Music Synthesizer Access Point Club Light System Club Sound System Master Slave Sensor
Outline • Motivation and Background • System design • Implementation • Lessons learned • Conclusions
Wireless sensor module Bluetooth Module RF Transceiver Bluetooth 1 Mbps ACL data link Baseband Controller UART Interface PIC Microcontroller 364 bytes RAM, 8 kB ROM Body Sensor Up to 5 sensors are supported
Sensor Data Acquisition Application MIDI Applications Presentation Layer Presentation Layer Bluetooth-to-IP Conversion Layer L2CAP L2CAP UDP HCI HCI UDP IP LMP LMP Baseband / RF Ethernet Baseband / RF IP Ethernet Protocol stack • For the wireless link, L2CAP only is used • Higher layers of Bluetooth & IP not used to save memory & time • Data sent to AP consists of sensor ID plus 7-bit digitized sensor value
DJ Console and Controller Configurator Data Filter MIDI Player Sensor data MIDI Song Files • Data Filter algorithms must keep output within acceptable ranges • Must be smooth yet obvious to participants • Must be flexible enough to give the DJ creative room • Must be accessible via a simple, intuitive GUI • Fertile area for future research!
MIDI • What is Musical Instrument Digital Interface (MIDI)? • binary data files containing instructions that tell electronic instruments how to play a song • much like musical scores • Why MIDI? • Much more efficient representation • PCM: 10 MB/minute of stereo audio sampled at 44.1 kHz • MIDI: 10 kB/minute • Can easily modify instructions in real time
Outline • Motivation and Background • System design • Implementation • Lessons learned • Conclusions
Related work • The Brain Opera, Machover 1996, 2000 • Not wireless • The Interactive Dance Club, Synesthesia 1998 • Not wireless • Cybershoe, Paradiso 1998 • Similar but limited to shoe, possible scalability issues, higher cost • CosTune, Nishimoto 2001 • Not a collaboration on a single song • Music in Motion, Ng 2000, 2001 • Interprets movement captured by a video camera • Web of Life, Center for Art and Media, Karlsruhe, permanent display • Most similar, video images change in response to users hand movements
Discussion • System Cost • Sensor module: • $500 for Bluetooth (Yr 2000), $100 for the rest • Expected cost in volume is ~$5 • Access point • About $1000 as implemented (with Linux single-board PC) • Can be easily reduced to ~$100 • DJ Console and converter • Standard PC with MIDI player: ~$1000 • Sound and light hardware • MIDI converter (MidiMan), Dance Synth (E’Mu Mo’Phatt), Audio Mixer (Mackie), Lighting Controller (DMX) • ~$4000
Discussion • Total Effort: 24 staff-months • Usability • Sensor module • 7 cm x 5 cm x 3 cm (without the sensor itself) • About 100 g • Size can be reduced (at least) 4x by one-chip Bluetooth module and Li-Ion polymer battery • DJ GUI • Data Filter algorithms
Wireless technology • codeBLUE requirements • differ slightly from those generally considered in the literature • Voice, video, web browsing, m-commerce transactions • Needs very low bandwidth (~2 kbps) but also low latency (< 100 ms) • Low-cost, small client size, low-power, rugged • Low maintenance cost and complexity • Bluetooth is adequate • Designed as a cable replacement • Low bandwidth, small size, low latency • Reasonable spectral efficiency • Easy serial interface
User module cost still too high Installation requires cabling to AP Expensive, cumbersome, unsightly, too fixed Power to AP could be avoided by batteries but currently consumption is too high Using wireless backhaul is problematic Bluetooth scatternet requires complex scheduling and may not meet time constraints 802.11b backhaul raises cost and interference issues Bluetooth Issues for codeBLUE
Other Bluetooth Issues • Spatial Capacity • Max of seven active slaves per master (~10m – 30m radius) • Can put slaves into PARK, HOLD etc but this is complex • The protocol stack is needlessly complex (for this application, at least) • Would prefer native IP running on a simple link layer • Security
What about good old 802.11b instead? • Cost still an issue • Power consumption is worse • 180-450 mA versus ~70 mA • Low spectral efficiency for small data packets • Hard to get delay guarantees (especially if shared) • Larger real-estate requirements, with large parallel bus • Cabling issues still arise
Conclusions • codeBLUE was demonstrated twice to a live audience • Stevens Inst of Technology annual Technogenesis Award, 2001 • Sensor technology is more than adequate • Bluetooth technology is adequate • Better than 802.11b • but not ideal • Ideal: • low-cost, low-power, multi-hop wireless telemetry network with • simple, efficient, IP-based, secure protocols and • rugged, disposable sensor clients
Further work • Needed • A protocol stack that provides IP, and • marries the simplicity of 802.11b with • the low power, size and spectral efficiency of Bluetooth • A low-cost, rugged wireless sensor module for human-scale measurements • Simple, configurable wireless security
Work in Progress • In progress: case study for research in Bluetooth security • DJ PC application rewritten in Java to allow real-time plug-in of 3rd party software to allow the DJ more choices • But plug-ins open security risks • Rely on Java and .NET code access security mechanism for runtime checks • But are these necessary and sufficient? • Use static analysis [Banerjee02,Banerjee02a]