Performance Analysis of Voice Transfer Using Multi-Transceiver Optical Communication Structures

1. Performance Analysis of Voice Transfer Using Multi-Transceiver OpticalCommunication Structures Abdullah Sevincer, Hasan T. Karaoglu, and Murat Yuksel asev@cse.unr.edu, karaoglu@cse.unr.edu, yuksem@cse.unr.edu Project Website: http://www.cse.unr.edu/~yuksem/fso-manet.htm IEEE ICSOS 2011, Santa Monica, CA

2. Outline • Motivation • Literature Survey • Previous work & LOS Algorithm • Prototype Implementation • Experiments & Results • Conclusion & Future Work

3. Motivation • RF spectrum is highly saturated – need alternative mediums for MANETs • Free-Space-Optical communication may serve as an alternative complementary medium to RF • Spectrum characteristics • 100+ GHz bandwidth • Low power per bit • License free • Directional communication • Spatial reuse • Low probability of intercept • Full-duplex transceivers • Device characteristics • Smaller form factor – dense packaging is possible • More durable • Issues to be solved (among others): • LOS – availability, and detection when available • Mobility or sway – LOS maintenance

4. Free-Space-Optical Ad Hoc Networks Motivation: FSO-MANETs Free-Space-Optical (FSO) Communications Mobile Ad-Hoc Networking • High bandwidth • Low power • Dense spatial reuse • License-free band of • operation • Mobile communication • Auto-configuration • Spatial reuse and angular diversity in nodes • Low power and secure • Electronic auto-alignment • Optical auto-configuration (switching, routing) Project Website: http://www.cse.unr.edu/~yuksem/fso-manet.htm

5. Motivation: FSO-MANETs • Our approach and focus to achieve the vision of FSO-MANETs • Low altitude and shorter ranges • LOS becomes the major issue not the visibility • Obstacles are common than the visibility problems • Cheaper devices (LEDs) with redundancy • Packaging and managing many transceivers per node • Electronic steering becomes possible if packaging provides angular diversity • No need for mechanical steering

6. Motivation • Electronic steering over multi-transceiver FSO nodes • By using multiple transceivers per node and automatically detecting neighbor nodes that are in LOS each other, we showed how to maintain the LOS alignment on FSO nodes. [IEEE ICC’10] • Question: “Can we use such multi-transceiver structures for streaming-style applications which may require little or no disconnection?” 3-D optical antenna design.

7. FSO Literature • High altitudes and longer ranges • FSO communications with a focus on coding and modulation techniques • Attaining longer transmission ranges, hardware design issues, and solutions against mobility • Focus on long distance (up to 7 kms) point-to-point applications with employing high-speed laser or VCSEL hardware. • Our focus: Low altitudes and shorter ranges

8. FSO Literature • Multiple elements/transceivers in FSO communication in interconnects which communicate over very short distances. • The main issues: • interference (or cross-talk) between adjacent transceivers due to finite divergence of the light beam • Misalignment due to vibration.

9. FSO Literature • FSO transmitters are highly directional: • comes with a cost of LOS alignment problem • Requires smart mechanisms to manage LOS among transceivers during an ongoing transmission. • Mechanical systems: (High maintenance and expensive, not fast enough to recover disruptions, multi-point-to-multi-point communication are not considered). • Our focus: Electronic steering with a redundancy of transceiver devices

10. Previous Work & LOS Detection Algorithm • Instead of mechanical steering, we implemented “electronic steering” over spherical optical antennas. • LOS detection and alignment establishment protocol via fast handshakes among transceivers of neighboring nodes. • Quick and automatic hand-off of data flows among different transceivers • Omni-directional propagation and spatial reuse at the same time • Assigning logical data streams to appropriate physical transceivers/channels

11. Prototype Implementation • Improved prototype with faster transceivers • Voice file transfers to evaluate performance of our LOS detection and alignment establishment protocol over streaming-style application traffic. • Mean Opinion Score (MOS) to evaluate voice transfer.

12. Prototype-Hardware • Controller Board: • PIC32 Ethernet Starter Kit • Expansion board • FSO Transceivers

13. Prototype-Setup NODE-B NODE-A TR1-A TR-B Wireless Link NODE-C TR-C TR2-A Wireless Link

14. Prototype-Experiments • Transceiver Performance Test: • Half Duplex Line • Portable Document File (PDF): 3637 bytes • File Transfer at varying distances NODE-B NODE-A TR-B Wireless Link

15. Prototype-Setup-Experiments NODE-B NODE-A TR1-A TR-B Wireless Link NODE-C TR-C TR2-A Wireless Link

16. Prototype-Experiments • Simultaneous File Transfer • Image Transfer from Node-A to both Node-B and Node-C • Half Duplex and Full Duplex Line • Image File Length: 7572 bytes • Voice File Transfer • 6 different voice file transfer for MOS evaluation • Voice File Transfer at varying distances

17. Results Image File Transfer Transceiver Performance Test Half Duplex Full Duplex MOS Performance: 6 Files MOS Performance: varying distance Unacceptable Quality Good MOS Values!

18. Conclusion & Future Work • Prototype: FSO system: multiple data streams • Simultaneous voice file transfers with minimal disruptions and overheads • Multimedia service with off-the-shelf components: Multi-transceiver & directionality • Future Work: • Improvement on the quality of voice transfer • Improve the prototype: faster transceivers • Link-and physical layer buffering mechanisms: reduce misalignment effects

19. Questions? Acknowledgments This work was supported by the U.S. National Science Foundation under awards 0721452 and 0721612 and DARPA under contract W31P4Q-08-C-0080