Laboratory

 Research directions of Software Communications and Navigation Systems Lab (SCNS) include wireless sensing, human activity data collection, localization technologies and supporting mobile applications.
The main topics are:

  • Wireless localization methods and platforms for mobile applications (GPS, GNSS, WLAN-based, etc);
  • Sensor data/signal collection and processing in mobile devices, their communication, and enabled applications;
  • Implementation approaches and platforms
  • Human-machine interaction systems, mHealth

 

 

 

 

 

Facility

The Software Communication and Navigation Systems Laboratory was established in 2004. Its currrent locations is BSE0.236. Through various funded projects, the Lab has acquired equipment and software worth of about $200K. This includes signal generators, up/down RF converters, signal analyzers, oscilloscopes, esc. My team also has access to a shared equipment/facility worth approximately $120K. Currently the Lab has significant potential to conduct state-of-the-art research. Major equipment list includes the following:
  • 5 Servers, 12 PC, 5 testing laptops
  • 8 USRP boards for SDR research
  • Advanced RF generators and analysers from NI and Agilent
  • In-house A-GPS testbed. In-house deployed and servicing MessageSpace systems for mHealth applications
  • WLAN-location testbed, 3rd party reference WLAN-location systems (Ekahau), WLAN mobile signal analyzer
  • Reference 3rd party GPS SDR receiver (Fastrax) and evaluation boards (SiRF)
  • Advanced RF-support boards from National Instruments
  • Antennas, parts, DSP processors, FPGA boards
  • HE-Robot WLAN enabled
  • Android, Symbian, Windows and Apple smartphones for application development
  • Supporting software
  • NI GPS Simulator

    Contact Information

    Director: Dr. David Akopian
    E-mail: david.akopian@utsa.edu
    Phone: (210) 458-7718

Research

My general research interests are in the area of wireless sensing and localization technologies supporting mobile applications. The diagram below summarizes three main topics and their subtopics. The main topics are: (a) wireless localization methods for mobile applications; (b) sensor data/signal collection and processing in mobile devices, their communication, and enabled applications; (c) implementation approaches and platforms supporting the two aforementioned topics. In addition, I chair the annual SPIE conference on mobile technologies as well as integrate my research with educational activities.

Research Projects

1. Federal

  • Agency: NIH R01
    Title: Healthy Frio: a rural community partnership to advance obesity research. UTSA portion: designing interactive applications tailored for trials with control groups, interactivity and analytic support
    Date (start-end): Oct 2016 – Sep 2020
  • Agency: NIH R01
    Title: Pediatric Obesity Management Intervention Trial for Hispanic Families. UTSA portion: designing tailored text messaging system tailored for trials with control groups, interactivity and analytic support
    Date (start-end): Apr 2014 – April 2019
  • Extending GPS Operation in GPS denied Areas through Cross-Correlation Jamming Cancellation”, Sponsored by USAF/USAFA, Federal, November 2015 – Dec 2017
  • Acquisition of Small Unmanned Aerial Systems for Advancing Cooperative
    Man-Machine Systems Research and Education”, Sponsored by US Dept of the Army, Federal, (February 1, 2015 – January 31, 2016).
  • UAV Operation in GPS-denied Environments”, Sponsored by AFRL/ONR, Federal, (September 2014 – December 2016).
  • Agency: Navy, NAVSEA. Title: UTSA Naval Engineering Education Center
    Date (start-end): Apr 2010 – Oct 2015
  • Agency: NSF
    Title: CCLI: Template-Based Undergraduate Education Concept in Wireless Application Development
    Date (start-end): Oct 2010 – Oct 201
  • Agency: NSF
    Title: CREST: Integrating High Performance Computing in Research and Education for Simulation, Visualization and Real-Time Prediction (SIVIRT)
    Date (start-end): 2009 – 2013
  • Agency: NIH R24
    Title: Partnership to Address Physical Activity among Low-Income Latino Adolescent Girls
    Date (start-end): Sep 2009 – Feb 2012
  • NSF Award #0833852
    Title: IP-Assisted GPS positioning
    Date (start-end): Nov 2008-Nov2009
  • NSF Award #0551501
    Title: CRI: Experimental Research in High-Performance Computing and Wireless Networking
    Date (start-end): May 2006 – May 2010
  • Navy STTR Phase I Contract No. N00014-08-M-0307
    Title: Navy STTR FY2008A – Topic N08 – Extensible Affordable Software Defined Radio with Cross-Band Cross-Protocol Capability”
    Date (start-end): July 2008 – Feb 2009
  • AFRL/UTSA Grant
    Title: Using advanced wireless and positioning technologies for intrusion detection and preventive security information systems
    Date (start-end): Dec 2006 – Dec 2007

2. State

  • (Active) Agency: SALSI (Collaborative UTHSCSA-UTSA)
    Title: Tobacco Cessation Services for Bi-Lingual and Spanish Speaking Young Adult Latinos in South Texas
    Date (start-end): May 1 2016 – Apr 30 2017
  • Agency: CPRIT (Collaborative UTHSCSA-UTSA)
    Title: Tobacco Cessation Services for Bi-Lingual and Spanish Speaking Young Adult Latinos in South Texas
    Date (start-end): Aug 31 2014 – Aug 30 2017
  • Agency: CPRIT (Collaborative YMCA-UTHSCSA-UTSA)
    Title: Y Living. Subcontract to set up a tailored messaging system
    Date (start-end): Sep 2011 – Aug 2013
  • Texas Higher Education Coordinating Board (THECB) Grant
    Title: Engineering Core Curriculum Redesign for Increasing Preparedness and Retention
    Date (start-end): Aug 2007- Aug 2009

3. Industry

  • Agency: HealthCheck
    Title: Gift to promote advanced health data collection research
    Date (start-end): Sep 2014 – May 2015
  • Agency: LiveOakLogic
    Title: Gift to promote advanced WLAN research
    Date (start-end): Sep 2012 – May 2013
  • Agency: NI
    Title: Data Analysis of NI GPS simulator
    Date (start-end): Dec 2007-May 2008

4. Other including sub-contracts, internal UTSA funding, institutional grants etc.

  • UTSA Tech POP funding
    Title: Enabling Robust Indoor Localization for Security and Emergency Applications
    Date (start-end): Sep 6. 2016 – Aug 31 2017
  • UTSA AT&T iTEC Center’s faculty member
    Duration: 2007-2012, currently remaining as a faculty mentor
  • Course Redesign Award, UTSA College of Engineering
    Title: Internet-based teaching of communication systems
    Date (start-end): Aug 2008 – Dec 2008
  • 2005 UTSA Faculty Research Award
    Title: Development of Assisted GPS Receivers for Weak Signal Conditions
    Date (start-end): Nov. 2005 – May 2006

Media

  • Texas Public Radio about automated interactive human-machine systems developed by SCNS Laboratory:

LINK

  • UTSA Today about SCNS Lab

LINK

Publications

Patents

  1. A. Khalajmehrabadi, N. Gatsis, D. Akopian, “Systems and Methods for Wireless Local Area Network Localization,” Patent application 62/408,665, 10.14.2016
  2. D. Akopian, R. Escobar, S. Kaghyan, “Interactive Mobile Service for Deploying Automated Protocols,” US Patent application 62/376,445, 08.18.2016
  3. D. Akopian, CJ Qian, D. Park, “Systems and Methods for a Mobile UAV-Based Emergency Communications Scanner,” Patent application 15194356, 06.27.2016
  4. D. Akopian, G. Huang, C.L.P. Chen, “Method and System for Measurement and Characterization of Channel Delays for Broadband Power Line Communications,” WO/2016/127048; PCT/US2016/016763, 11.08.2016
  5. D. Akopian, A. Melkonyan, M. Pontual, G. Huang; A. Gampe. “Remote Laboratory Gateway”. US Patent Application 20130117019 A1, May 9, 2013
  6. D. Akopian. “Determination of correlation in the frequency domain.” EP1692775A1, US20050128937
  7. D. Akopian, “Determination of the code phase between a code modulated signal and a replica code sequence,” US2004/0141574A1, 06.05.2004
  8. C. Lacatus, D. Akopian, M. Shadaram, “Crosscorrelation interference mitigating position estimation systems and methods therefor”, US Patent 8,548,106, Oct. 1, 2013
  9. S. Agaian, D. Akopian, et al. Methods and systems for digital image security. US Patent 8,369,568, Feb.5, 2013
  10. S. Agaian, D. Akopian, et al. Methods and systems for digital image security. US Patent 7,965,861, June.21, 2011
  11. D. Akopian, H. Valio. Preventing an incorrect synchronization between a received code-modulated signal and a replica code. US Patent 7,876,738, Jan 25, 2011
  12. D. Akopian, S. Turunen, S. Pietila, H. Valio, “Acquisition of a code modulated signal,” US Patent 7,336,696. Feb. 26, 2008.
  13. D. Akopian, “Determination of the correlation phase between a signal and a replica sequence,” US Patent 7,286,594. Oct. 23, 2007.
  14. D. Akopian, H. Valio, S. Pietila, J. Syrjarinne, “Validation of beacon signals,” US Patent 7,064,708. June 20, 2006.
  15. D. Akopian, H. Vallio, J. Syrjarinne, “Position estimation,” US Patent 6,894,645. May 17, 2005.
  16. D. Akopian, H. Valio, “Tracking a code modulated signal,” US Patent 7,124,352. Oct. 17, 2006.
  17. D. Akopian, “Determining the correlation between received samples and available replica samples,” US Patent 7,277,476, Oct. 2, 2007
  18. D. Akopian, “Determining the correlation between received samples and available replica samples,” US Patent 7,272,168, Sep. 18, 2007.
  19. D. Akopian, “Method and apparatus for acquiring a ranging signal of a positioning system,” US Patent 7,120,191. October 10, 2006.
  20. D. Akopian, K. Ilkka, H. Valio, S. Turunen “Method in a receiver and a receiver,” US Patent 6,909,738, Jun. 21, 2005.
  21. D. Akopian, H. Valio, S. Turunen “System for method for fine acquisition of a spread spectrum signal,” US Patent 6,909,736, Jun. 21, 2005.
  22. D. Akopian, J. Syrjarinne, “Position Estimation,” US Patent 6894645, May 17, 2005.
  23. D. Akopian, J. Syrjarinne, “Method, receiver and system for determining the time of reception of a beacon signal,” US Patent 6,833,813, Dec. 21, 2004.
  24. D. Akopian, “System for acquiring spread spectrum signals,” US Patent 6,810,072, Oct. 26, 2004
  25. D. Akopian, H. Valio, “Determination of the transmission time of a signal part in a positioning system,” US Patent 6,771,215, August 3, 2004.
  26. D. Akopian, J. Syrjarinne, “Method for determining the correlation between a received beacon signal and a reconstructed signal,” US Patent 6,768,451, July 27, 2004.
  27. D. Akopian, “Method, apparatus and system for fast acquisition of a spread spectrum signal,” US Patent 6,735,243, May 11, 2004.
  28. D. Akopian, “Method for providing time using multiple-clock model and a clock system using such a model”, US Patent 6,651,031, November 18, 2003.
  29. D. Akopian, “Clock system and corresponding method for providing a clock time accounting for systematic error”, US Patent 6,573,799, June 3, 2003.
  30. D. Akopian, J. Syrjarinne, “Method, apparatus and system for estimating user position with a satellite positioning system in poor signal conditions”, US Patent 6,473,694, October 29, 2002.
  31. D. Akopian, J. Syrjarinne, “Method and apparatus for calculating pseudorange for use in ranging receivers”, US Patent 6,466,164, October 15, 2002.
  32. D. Akopian, J. Syrjarinne, “Cross-correlation system for time recovery in network-assisted GPS positioning”, US Patent 6,459,407, October 1, 2002.

Books, Edited Books/Proceedings, Book Chapters

  1. Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2016, Reiner Creutzburg; David Akopian, Editors, IS&T, ISSN 2470-1173.
  2. Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2015, Reiner Creutzburg; David Akopian, Editors, Proceedings of SPIE Vol. 9411
  3. J. Morales, S. Kaghyan, D. Akopian, S. Agaian, “Human activity recognition and processing for mobile applications,” Chapter 8 in Mobile Imaging, SPIE, 2016
  4. Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2014 (Editors: R. Creutzburg, D. Akopian)
  5. SPIE: Multimedia content and mobile devices (Editors: N. Sebe, R. Creutzburg, A. Lumsdane, D. Akopian, C.G.M. Snoek, D. Wuller, 2013)
  6. SPIE Multimedia on Mobile Devices, Editors: R. Creutzburg, D. Akopian, 2012
  7. SPIE Multimedia on Mobile Devices, Editors: R. Creutzburg, D. Akopian, 2011
  8. SPIE Multimedia on Mobile Devices, Editors: R. Creutzburg, D. Akopian, 2010
  9. SPIE Multimedia on Mobile Devices, Editors: R. Creutzburg, D. Akopian, 2009
  10. D. Akopian, Systematic Approaches to Parallel Architectures for DSP Algorithms, 1997, Acta Politechnica Scandinavica, EI 89, Espoo, Finland, ISBN 952-5148-29-7
  11. D.Akopian, J. Takala, J.Saarinen, J. Astola, “Multistage interconnection networks for parallel Viterbi decoders,” Proceedings of First International Workshop on Spectral Techniques and Logic Design for Future Digital Systems, Chapter in TICSP Series #10, December 2000, pp.131-155.
  12. D. Akopian, M. Helsingius & J. Astola,”Multibase Approaches for Compression of Still Images,” Chapter in TICSP Series 4, International Workshop on Transforms and Filter Banks (WTFB’99), March 5-7, 1999, Brandenburg an der Havel, Germany, 16p.
  13. D. Akopian and J. Astola, “Fast architecture oriented algorithms for trigonometric transforms and their mapping to scalable structures,” First International Workshop on Transforms and Filterbanks, Chapter in TICSP Series-1, June 1998, pp. 433-471.

Journal Papers

  1. A. Khalajmehrabadi, N. Gatsis, D. Pack, D. Akopian, “Collaborative Least Squares Localization”, submitted to IEEE Transactions on AES, Jan 2017.
  2. A. Khalajmehrabadi, N. Gatsis, A. Taha, D. Akopian, “Real-Time Rejection and Mitigation of Time Synchronization Attacks on the Global Positioning System,” submitted IEEE Transactions on Industrial Electronics, June 2017.
  3. (in-press) A. Khalajmehrabadi, N. Gatsis, D. Akopian, “Structured Group Sparsity: A Novel Indoor WLAN Localization, Outlier Detection, and Radio Map Interpolation Scheme,” IEEE Trans. on Vehicular Technology, 2016, DOI: 10.1109/TVT.2016.2631980
  4. (early access) A. Khalajmehrabadi, N. Gatsis, D. Akopian, “Modern WLAN fingerprinting indoor positioning methods and deployment challenges,” IEEE Communications Surveys & Tutorials, DOI: 10.1109/COMST.2017.2671454
  5. A. Khalajmehrabadi, N. Gatsis, D. Akopian, “A Joint Indoor WLAN Localization and Outlier Detection Scheme Using LASSO and Elastic-Net Optimization Techniques,” IEEE Trans. on Mobile Computing, Vol. 1, No 8, pp.2079-2092, 2017, DOI: 10.1109/TMC.2016.2616465
  6. (in-press) A. Khalajmehrabadi, N. Gatsis, D. Akopian, “A Joint Indoor WLAN Localization and Outlier Detection Scheme Using LASSO and Elastic-Net Optimization Techniques,” IEEE Trans. on Mobile Computing, 2017, DOI: 10.1109/TMC.2016.2616465
  7. J. Morales, D. Akopian, “Physical activity recognition by smartphones, a survey,” Elsevier Biocybernetics and Biomedical Engineering Journal, Vol. 37, No.3, doi.org/10.1016/j.bbe.2017.04.004, 2017
  8. G.Huang, M.M. Miller, D.Akopian, “Inference of Network Delays for SUPL3.0 Assisted GNSS,” GPS Solutions, (2016). doi:10.1007/s10291-016-0549-6
  9. J. Morales, D. Akopian, “Human activity tracking by mobile phones through Hebbian Learning,” Int. Journal of Artificial Intelligence and Applications, Vol.7, No.6. Nov. 2016, DOI: 10.5121/ijaia.2016.7601
  10. J. Morales, D. Akopian, S. Agaian, “Dual polynomial thresholding for transform denoising in application to local pixel grouping method,” The Int. Journal of Multimedia & Its Applications (IJMA), Vol. 8., No.1, Feb 2016, DOI : 10.5121/ijma.2016.8101.
  11. J. Morales, D. Akopian, S. Agaian, “Mitigating anomalous measurements for indoor WLAN positioning,” IET Radar Sonar and Navigation, Vol. 10, No.7, pp. 1220-1227, 2016.
  12. A.M.Mayers, P. Benavidez, D. Akopian, GVS Raju, M. Jamshidi, “A closed loop transmission power control system using a nonlinear approximation of power-time curve,” IEEE Systems Journal, Vol.9, No.3, pp.1011-1019, 2015
  13. G.Huang, D. Akopian, and C.L. P. Chen, “Network Delay Modeling for Assisted GPS” IEEE Trans. Aerospace and Electronic Systems, Vol.51,No.1, pp.52-64, 2015
  14. J. Morales, D. Akopian, S. Agaian, “Faulty measurements impact om wireless local area network positioning performance,” IET Radar Sonar and Navigation Journal, Vol.9, No.5, pp.501-508, 2015
  15. G.Huang, D. Akopian, and C.L. P. Chen, “Statistical Characterization of Channel Delays for Broadband Power Line Communications,” IEEE Trans. on Instrumentation and Measurement, Vol. 63, No.1, pp. 2583 – 2590, 2014
  16. A. Soghoyan, A. Suleiman, D. Akopian, “A LabVIEW Based GPS Receiver Development and Testing Platform With FPGA Peripherals: Case Study With FlexRIO FPGA Module”, IEEE Trans. on Instrumentation and Measurement, Vol. 63, No.8, pp. 2001-2012, 2014
  17. G.Huang, D. Akopian, and C.L. P. Chen, “Measurement and Modeling of Network Delays for MS-based A-GPS Assistance Delivery,” IEEE Trans. on Instrumentation and Measurement, Vol. 63, No. 8, pp. 1896-1906, 2014.
  18. C. Mojica, D. Parra-Medina, D. Akopian, “Accessing media access and use among Latina adolescents to inform development of a physical activity promotion intervention incorporating text-messaging,” SAGE Health Promotion Practice, Dec 19, 2013, doi:10.1177/1524839913514441
  19. A. Melkonyan, D. Akopian, “Assessment of Template-Based Learning in Application Development for Smart Phones”, IEEE Technology and Engineering Education Magazine (formerly Multidisciplinary Engineering Education Magazine), Vol.8, No.3, pp.20-28, 2013
  20. A. Melkonyan, A. Gampe, M. Pontual, G. Huang, D. Akopian, “An assessment of remote laboratory experiments in radio-communication,” IEEE Trans. on Education, Vol.57, No.1, pp.12-19, Feb. 2014
  21. A. Melkonyan, A. Gampe, M. Pontual, G. Huang, and D. Akopian, “Facilitating Remote Laboratory Deployments Using Relay Gateway Server Architecture”, IEEE Transaction on Industrial Electronics, Vol. 61, No. 1, pp. 477-485, 2014.
  22. D. Akopian, A. Melkonyan, S.C. Golgani, T.T. Yuen, and C. Saygin, “A Template-Based Short Course Concept on Android Application Development”, JITE: Research, Vol. 12, pp. 13-28, 2013 (cites/paper 11.4, h-index 28).
  23. D. Akopian, P. Sagiraju, B. Nowak, “Fast time-recursive block correlators for pseudorandom sequences,” IEEE Trans. on Circuits and Systems I, Vol. 60, No.7, 2013, pp.1835-1844
  24. A. Soghoyan, D. Akopian, “A LabVIEW-Based GPS Receiver Development and Testing Platform with DSP Peripherals: Case study with C6713 DSK”, Journal of Global Positioning Systems, Vol.11, No.2, pp.127-144, 2012.
  25. M. Shadaram, D. Akopian, G. H. S. Carvalho: Guest Editors’ Introduction to the Special Issue on The design and analysis of wireless systems: New inspirations. Elsevier Computers & Electrical Engineering 38(3): 471-472 (2012)
  26. T. Yuen, C. Saygin, H. Shipley, H. Wan, and D. Akopian, “Factors that Influence Students to Major in Engineering,” International Journal of Engineering Education, (IF 0.3) Vol. 28, No. 4, 2012, pp.1-7.
  27. C. Lacatus, D. Akopian, M. Shadaram, “Reduced complexity crosscorrelation interference mitigation in GPS- enabled collaborative ad-hoc wireless networks – Theory,” Computer and Electrical Engineering Journal, Elsevier, May 2012, Vol. 38, No.3, 2012, pp. 603-615.
  28. A. Panchul, D. Akopian, M. Jamshidi, “Temporal-Spatial Fuzzy Logic Algorithm for Effective Dynamic Load Balancing in Distributed 3D Graphics Engine,” International Journal of System of Systems Engineering, Vol. 2, No. 4, 2011, pp. 309-328
  29. D. Akopian, A. Melkonyan, C.L.P. Chen, “Validation of HDOP Measure for Impact Detection in Sensor Network-Based Structural Health Monitoring” IEEE Sensors Journal, Vol. 9, No 9, 2009, pp.1098–1102
  30. D. Akopian, J. Syrjarinne, “A Fast Positioning Method Without Navigation Data Decoding for Assisted GPS Receivers,” IEEE Transactions on Vehicular Technology, Vol. 58, No. 8, 2009, pp. 4640 – 4645.
  31. C. Lacatus, P. Yaddanapudi, D. Akopian, M. Shadaram, “Dynamic spectrum and power allocation for unlicensed wireless systems,” IEEE Systems Journal, Vol. 3, No. 2, 2009, pp. 254-264.
  32. C. Lacatus, D. Akopian, M. Shadaram, “Reduced complexity for optimal spreading sequence design,” IEEE Transactions on Circuits and Systems – II, Vol.55, No.12, Dec. 2008, pp. 1309-1313.
  33. P. Sagiraju, G.V.S. Raju, D. Akopian, “Fast acquisition implementation for high sensitivity global positioning system receivers based on joint and reduced space search,” IEE Proceedings on Radar, Sonar, and Navigation, Vol. 2, No. 5, Oct. 2008 pp. 376 – 387
  34. C. Smith, S. Agaian, D. Akopian, “A wavelet-denoising approach using polynomial threshold operators,” IEEE Signal Processing Letters, Vol. 15, 2008, pp. 906 – 909
  35. D. Akopian and S. Agaian, “A fast time-recursive correlator for DSSS systems,” IEEE Signal Processing Letters, Vol. 15, 2008, pp. 589 – 592
  36. D. Akopian, “On optimal bit allocation for classification-based source-dependent transform coding,” Research Letters in Signal Processing, vol. 2008, ID 421650. (available at www.hindawi.com)
  37. D. Akopian and S. Agaian, “Fast matched Filters in Time Domain,” IEE Proceedings on Radar, Sonar & Navigation, vol 153, No.6, Dec 2006, pp. 525-531. (IEEE Xplore)
  38. P. Sagiraju, S. Agaian, D. Akopian, “A Reduced Complexity Acquisition of GPS Signals for Software Embedded Applications” IEE Proceedings on Radar, Sonar & Navigation, Vol. 153, No.1, Feb 2006, pp. 69-78. (available at IEEEXplore)
  39. D. Akopian, “Fast FFT Based GPS Satellite Acquisition Methods” IEE Proceedings on Radar, Sonar & Navigation, Vol. 152, No. 4, August 2005, pp. 277-286. (available at IEEEXplore, a top accessed paper since publication)
  40. D. Akopian and J. Astola, “An optimal nonlinear extension of linear filters based on distributed arithmetic,” IEEE Transactions on Image Processing, Vol. 14, Issue 5, May 2005, pp. 616-623.
  41. H. Sairo, D. Akopian, J. Takala, “ Weighted dilution of precision as quality measure in satellite positioning”, Radar, Sonar and Navigation, IEE Proceedings, Vol. 150 , Issue: 6 , 1 Dec. 2003, pp: 430 – 436. (available at IEEEXplore)
  42. D. Akopian, J. Takala, J. Saarinen, J. Astola, “Multistage interconnection networks for parallel Viterbi decoders,” IEEE Transactions on Communications, Vol. 51, No.9, Sep 2003, pp.1536-1545.
  43. J. Takala, D. Akopian, J. Astola, J. Saarinen “Constant geometry algorithm for Discrete Cosine Transform” IEEE Transactions On Signal Processing, vol. 48, No.6, June 2000, pp. 1840-1843
  44. J. Astola and D. Akopian, “Architecture oriented regular algorithms for a class of trigonometric transforms,” IEEE Transactions Signal Processing., April 1999, pp. 1109-1124
  45. J. Astola, D. Akopian, “A time-recursive implementation of threshold Boolean filters,” IEEE Trans. Circuits and Systems II, February 1999, pp. 139-148.
  46. J. Astola, D. Akopian, O. Vainio, S. Agaian, “Digit-serial architectures for stack filters,” EURASIP Signal Processing Journal, in vol. 61, pp. 181-197, September 1997.
  47. D. Akopian, O. Vainio, S. Agaian, and J. Astola, “SBNR processor for stack filters,” IEEE Trans. Circuits and Systems II, vol. 44, pp. 197-208, Mar. 1997.
  48. D. Akopian, O.Vainio, J.Astola, “Processors for generalized stack filters,” IEEE Trans. On Signal Processing, vol. 43, no. 6, pp. 1541-1546, June, 1995.

Invited Talks and Presentations

  1. D. Akopian, “Indoor Location Technologies” IEEE WISPNET Conference, 22-24 March 2017, Chennai, India
  2. D. Akopian, Ali Khalajmehrabadi, N. Gatsis, “Introduction to WLAN-Based Indoor Positioning of Mobile Devices,” IS&T EI Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2017, Jan 29-Feb2. 2017. Burlingame, CA
  3. D. Akopian, “Advanced Messaging Solutions for Mobile Health Promotion Research, “ Invited Presentation at Biowireless Research in Texas towards m-Health, Radio & Wireless Week, 24-27 January 2016, Austin, TX
  4. D. Akopian, A. Soghoyan, “A LabVIEW-Based Fast Prototyping Software Defined GPS Receiver Platform,” GlobalSIP 2013, Dec 3-5, 2013, Austin, TX (Invited to Sofware Defined and Cognitive Radios Symposium)
  5. D. Akopian, V. Jayaram, L. Aaleswara, M. Esfahanian, C. Mojica, D. Parra-Medina, S. Kaghyan, ”Mobile Text Messaging Solutions for Obesity Prevention,” SPIE Electronic Imaging/Multimedia on Mobile Devices Conference, Jan 24-27, San Francisco, CA, 2011.
  6. D. Akopian, WLAN positioning and related topics, Southwest Research Institute, Nov 2010
  7. Invited Keynote Speaker. Assisted GPS Technology, Association of Old Crows, Joint Electronic Warfare Center, Lackland Base, San Antonio, Jan 15, 2010
  8. A. Kumar, D. Akopian, S. Agaian, R. Creutzburg, “A mobile-to-server link for wireless steganography,” SPIE Electronic Imaging/Multimedia on Mobile Devices Conference, San Jose, CA, Jan 2009.
  9. D. Akopian. Invited Speaker. 2009 National Instruments Week. Using NI Equipment to Enhance Education and Research. A Case Experience at UTSA, August 2009. Austin, TX.
  10. D. Akopian, Introduction to A-GPS Positioning, IEEE Signal Processing and Communications Chapter, IEEE SMC Chapter, San Antonio, TX, Spring 2009
  11. D. Akopian, “Satellite positioning systems,” presented at American University of Armenia, and the Institute of Problems of Informatics and Cybernetics, Yerevan Armenia, June 2007.
  12. D. Akopian, “Mapping of fast transform algorithms to scalable structures,” Short Course, Summer School on Multimedia and Computer Networking, Mangalia, Romania, 2-9 Aug. 1998.

Other (refereed):

  1. J.Morales, R.Escobar, S.Kaghyan, G.Natarajan, D.Akopian, P. Chalela, A. Ramirez, A. McAlister, “Two-tier state-machine programming for messaging applications,” IS&T Int. Symposium on Electronic Imaging: Mobile Devices and Multimedia, Jan 29 – Feb 2, 2017, Burlingame, CA.
  2. A. Khalajmehrabadi, N. Gatsis, D. Akopian, “Indoor WLAN localization using group sparsity optimization technique,” 2016 IEEE/ION Position, Location and Navigation Symposium (PLANS), 2016, pp. 584 – 588, DOI: 10.1109/PLANS.2016.7479749
  3. A. Khalajmehrabadi, N. Gatsis, D. Akopian, “Range-based trilateration using multipurpose cost function optimization with Lagrangian multipliers,” 2016 IEEE/ION Position, Location and Navigation Symposium (PLANS),2016, pp. 118 – 121, DOI: 10.1109/PLANS.2016.7479690
  4. G. Huang, M.M. Mikel, D. Akopian, “Network Delay Modeling and Estimation for A-GNSS Supports Over Cellular Networks,” ION-ITM 2016, Jan 25-28, Monterey, CA.
  5. B. Kelley, G. De La Torre Parra, D. Akopian, “Cognitive inference avoidance in 4th generation GPS,” 10th IEEE System of Systems Engineering Conference (SoSE), May 17-20, 2015, San Antonio, TX, pp.410-415, 2015
  6. Sahak Kaghyan, David Akopian, Hakob G. Sarukhanyan, “Platform-dependent optimization considerations for mHealth applications”, Proceedings of SPIE Vol. 9411, 94110K (2015) SPIE Digital Library
  7. Erick Schmidt, David Akopian, “Indoor positioning system using WLAN channel estimates as fingerprints for mobile devices”, Proceedings of SPIE Vol. 9411, 94110R (2015) SPIE Digital Library
  8. Rodrigo Escobar, David Akopian, Rajendra Boppana, “A sensor data format incorporating battery charge information for smartphone-based mHealth applications”, Proceedings of SPIE Vol. 9411, 941103 (2015) SPIE Digital Library
  9. Lakshmipathi Aaleswara, David Akopian, Anthony T. Chronopoulos, “A privacy protection for an mHealth messaging system”, Proceedings of SPIE Vol. 9411, 94110S (2015) SPIE Digital Library
  10. S. Agaian, M. Roopaei, D. Akopian, “Thermal-image quality measurements,” IEEE ICASSP’2014 Conference, Florence, Italy, May 4-9, 2014, pp.2761-2765,
  11. R.G. Ekanthappa, R. Escobar, A. Matevossian, D. Akopian, “A remote laboratory for USRP-based software defined radio,” SPIE EI Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2014, Feb 3-5, 2014, San Francisco, CA.
  12. J. Morales, D. Akopian, S. Agaian, “Dealing with Faulty Measurements in WLAN Indoor Positioning”, SPIE EI Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2014, Feb 3-5, 2014, San Francisco, CA. pp.90300P1-10.
  13. J. Morales, D. Akopian, S. Agaian, “Human Activity Recognition by Smartphones Regardless of Device Orientation”, SPIE EI Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2014, Feb 3-5, 2014, San Francisco, CA. 90300I1-12
  14. A. Saha, D. Akopian, “Indoor positioning system using WLAN multipath signals as fingerprints for mobile devices,” SPIE EI Mobile Devices and Multimedia: Enabling Technologies, Algorithms, and Applications 2014, Feb 3-5, 2014, San Francisco, CA, 90300H1-7
  15. A. Mayers, B. Kone, GVS Raju, D. Akopian, “An adaptive stochastic-based M-ary modulation extension algorithm for short range wireless CRs,” IEEE Eireless Telecommunications Symposium (WTS), Apr 17-19, Phoenix, AZ.
  16. A. Mayers, P. Benavidez, GVS Raju, D. Akopian, M. Jamshidi, “A novel BER-feedback power control algorithm for PAN devices,” IEEE Int. Systems Conference (SysCon), Apr 15-18, 2013, Orlando, FL, pp.370-375.
  17. S. Kaghyan, H. Sarukhanyan, D. Akopian, Human movement activity classification approaches that use wearable sensors and mobile devices, Proc. SPIE 8667, Multimedia Content and Mobile Devices, 86670O (March 7, 2013); doi:10.1117/12.2007868
  18. R. D. Escobar, D. Akopian, D. Parra-Medina, L. Esparza, “MessageSpace: a messaging system for health research”, Proc. SPIE 8667, Multimedia Content and Mobile Devices, 86670V (March 7, 2013); doi:10.1117/12.2007530
  19. A. Soghoyan, D. Kinjarapu, D. Akopian, “Fast Prototyping of Receiver Accelerators Using NI Labview FPGA,” ION GNSS 2013, Sep. 16-20, Nashville, TN, 2013, pp.1577-1526
  20. G. Huang, D. Akopian, A-GPS Assistance Network Delay Modeling and Estimation Over Mobile Networks: ION GNSS 2013, Sep. 16-20, Nashville, TN, 2013
  21. S. C. Golagani, M. Esfahanian, D. Akopian, Template–Based Image Processing Toolkit for Mobile Platforms, SPIE Electronic Imaging: Multimedia on Mobile Devices Conference, San Francisco, CA, Jan 24-25, 2012, pp. 83040O1-11.
  22. J. Narisetty, A. Soghoyan, M. Sundaramurthy, D. Akopian, “SUPL Support for Mobile Devices” SPIE Electronic Imaging: Multimedia on Mobile Devices Conference, San Francisco, CA, Jan 24-25, 2012, pp 830409:1-12
  23. C. Saygin, T. Yuen, H. Shipley, H., H. Wan, and D. Akopian, XYZ* Center for K-12 STEM education: from summer camps to robotics competitions, ASEE Annual Conference, San Antonio, TX, AC2012-3021, 2012
  24. G. Huang, A. Melkonyan, M. Pontual, A. Gampe, David Akopian, Remote experimentation for communications: from remote desktops to gateways”, ASEE Annual Conference, San Antonio, TX, AC2012-3303, 2012
  25. B. Chandana, M. Esfahanian, D. Akopian, C. Saygin, “Template–based image processing toolkit for Android phones”, ASEE Annual Conference, San Antonio, TX, AC2012-3546, 2012
  26. D. Akopian, A. Melkonyan, S. Yalamachili, and P. Chen, “Integrated Monitoring and Mobile Implementation Aspect of WLAN Positioning” , in Proc. of ICSSE 2011, Macau, China, June 2011, pp. 688-693
  27. A. Melkonyan, S. Yalamachili, D. Akopian, and P. Chen, “Integrated Monitoring and Thresholding-Based WLAN Indoor Positioning Algorithm for Mobile Devices” , in Proc. of SoSE 2011, Albuquerque NM, USA, 2011, pp.191-196
  28. A. Melkonyan, M. Pontual, G. Huang, A. Gampe, D. Akopian “eComLab: Remote Laboratory Architecture of Radio-Communications,” 11th ASEE-GSW Conference-Innovating Engineering and Engineering Technology Education, March 9-11, 2011, F2A-1, Houston, TX.
  29. A. Kumar, M. Esfahanian, A. Melkonyan, D. Akopian, “Template-based education in mobile application development,” 11th ASEE-GSW Conference-Innovating Engineering and Engineering Technology Education, March 9-11, 2011, T3B-4, Houston, TX.
  30. M. Pontual, A. Melkonyan, A. Gampe, G. Huang, D. Akopian, “eComLab: remote laboratory platform,” SPIE Mobile Multimedia/Image Processing, Security, and Applications, vol. 8063, Apr. 25-29, 2011, Orlando, FL., 806311:1-10
  31. G. Ramachandran, D. Akopian, G.W. Heckler, L. B. Winternitz, “Performance evaluation of block acquisition and tracking algorithms using an open source GPS receiver platform,” Institute of Navigation, 2011 ITM Conference, Jan 24-26, 2011, San Diego, CA, pp.759-766.
  32. D. Akopian, A. Soghoyan, S.N. Chayapathi, “A feasibility study of a Labview-based GNSS receiver,” Institute of Navigation, 2011 ITM Conference, Jan 24-26, 2011, San Diego, CA, pp.1270-1280.
  33. A. Soghoyan, G. Huang, J. Narisetty, D. Akopian, “A Labview-Based Assisted GPS Receiver Development, Simulation and Testing Platform,” ION GNSS 2011 Conference, Portland, OR, Sep 20-23, 2011, pp.1982-1994
  34. A. Suleiman, D. Kinjarapu, D. Akopian, F. Hudson, “Reconfigurable correlator accelerators for software GPS receivers,” ION GNSS 2011 Conference, Sep. 20-23, 2011, Portland, OR, pp. 3720-3728
  35. M. C. Sundaramurthy, S.. N. Chayapathi, A. Kumar, D. Akopian, “Wi-Fi assistance to SUPL-based Assisted-GPS simulators for indoor positioning,” Proceedings of IEEE Consumer and Networking Conference, Jan 9-12, 2011, Las Vegas, NV, pp 918-922,
  36. S. Sathyanarayana, D. Akopian, S. Agaian, “An adaptive LMS technique for wavelet polynomial threshold denoising,” SPIE Mobile Multimedia/Image Processing, Security, and Applications, vol. 8063, Apr. 25-29, 2011, Orlando, FL., pp. 806308:1-10
  37. M. Chan, S. Sathyanarayana, D. Akopian, S. Agaian, “Application of wavelet polynomial threshold for interpolation and denoising in bioimaging,” SPIE Mobile Multimedia/Image Processing, Security, and Applications, vol. 8063, Apr. 25-29, 2011, Orlando, FL, pp. 80630Z1-12
  38. M. Chan, S. Sathyanarayana, D. Akopian, S. Agaian, “Multiple user access and testing for PreNotiS: a fast mobile event reporting solution,” SPIE Mobile Multimedia/Image Processing, Security, and Applications, vol. 8063, Apr. 25-29, 2011, Orlando, FL, pp. 80630Y1-8.
  39. B. Kalgikar, D. Akopian, P. Chen, “A signal strength priority based position estimation for mobile platforms,” Multimedia on Mobile Devices, Proc. SPIE, vol. 7542, 2010, pp. 75420F1-10
  40. A. Hussein, A. Suleiman, N. Kerkiz, D. Akopian, “Scalable interconnect networks for Discrete Cosine Transforms (DCT) for mobile multimedia applications,” 53rd IEEE Int. Midwest Symposium in Circuits and Systems (MWSCAS), Aug 1-4, 2010, pp.741-744.
  41. N. Kerkiz, A. Hussein, A. Elchouemi, A. Suleiman, “Design method for scalable discrete trigonometric transforms (DTT) with constant geometry,” 53rd IEEE Int. Midwest Symposium in Circuits and Systems (MWSCAS), Aug 1-4, 2010, pp.745-748.
  42. A. Melkonyan, D. Akopian, C.L.P. Chen, “A sensor placement measure for impact detection in structural health monitoring” IEEE International Conference on Systems, Man and Cybernetics, 2009. SMC 2009, 11-14 Oct. 2009, pp. 3775 – 3778
  43. A. Melkonyan, D. Akopian, C.L.P. Chen, “A remote over-internet hands-on laboratory” IEEE International Conference on Systems, Man and Cybernetics, 2009. SMC 2009, 11-14 Oct. 2009, pp. 4634– 4640
  44. G. Huang, A. Soghoyan, D. Akopian, C.L.P. Chen, S. Abhay, “A land mobile channel modeling in LabVIEW,” IEEE International Conference on Systems, Man and Cybernetics (SMC), Oct. 11-14, 2009, San Antonio, TX, pp. 4575 – 4580
  45. A. Melkonyan, D. Akopian, C.L.P. Chen, “Work in progress – real-time remote Internet-based communication laboratory,” 39th IEEE Frontiers in Education Conference, 2009. FIE ’09, 18-21 Oct. 2009
  46. S.N. Chayapathy, A. Kumar, P. Kashyap, D. Akopian, A. Samant, “A SUPL-based A-GPS Simulator Support for Indoor Positioning,” Proceedings of ION GNSS Conference, Sep 22-25, 2009, Savannah,GA, pp.503-515.
  47. A. Hussein, A. Suleiman, ,”Implementation of scalable interconnect networks for data reordering used in Discrete Trigonometric Transforms (DTT),” IEEE ICICDT’2009 Int. Conference, May 18-20, 2009, pp. 139-142.
  48. A. Kumar, D. Akopian, P. Chen, “Performance study of a mobile preventive notification system (PreNotiS),” SPIE Electronic Imaging/Multimedia on Mobile Devices Conference, San Jose, CA, Jan 2009, pp. 72560F1-12
  49. P. Kashyap, D. Akopian, A. Samant, “An assisted GPS messaging for GPS simulators for embedded mobile positioning”, SPIE Electronic Imaging/Multimedia on Mobile Devices Conference, San Jose, CA, Jan 2009. pp. 72560G1-12.
  50. A. Kumar, D. Akopian, P. Chen, “A dynamic client/server message-exchange application for mobile phones”, SPIE Electronic Imaging/Multimedia on Mobile Devices Conference, San Jose, CA, Jan 2009.
  51. S. Yerubandi, M. Gunturu, A. Melkonyan, D. Akopian, P. Chen, “Integrity Monitoring In WLAN Positioning Systems”, SPIE Defence and Security Conference, Orlando, FL, Apr. 2009, pp. 735109:1-12
  52. C. Lacatus, D. Akopian, M. Shadaram, “Adaptive OFDMA Scheme for spectrum and power allocation”, World Automation Congress, Sep. 2008.
  53. A. Panchul, D. Akopian, P. Chen, “Mobile Event Reporting for Symbian platforms”, World Automation Congress, Sep. 2008.
  54. P.K. Sagiraju, P. Kashyap, D. Akopian, “Block Correlator for Tracking GNSS Signals,” ION GNSS 2008 Conference, Savannah, Georgia, Sep. 16-19, 2008.
  55. A. Panchul, D. Akopian, “Educational Applications Development for Smartphones,” ASEE Annual Conference, June 2008, Pittsburgh, PA.
  56. C. Lacatus, D. Akopian, M. Shadaram, “Implementation Approaches of Adaptive Algorithms for Crosscorrelation Effect Compensation in Weak Signal Conditions,” Proceedings of IEEE PLANS 2008 Conference, Monterey, CA, May 5-8, 2008.
  57. D. Akopian, P. Chen, M. Gunturu, P. Sagiraju, “Implementation of an intrusion detection system based on wireless positioning”, Proceeding of SPIE, Vol. 6982, pp. 698205-698205-11. Mobile Multimedia/Image Processing, Security, and Applications, March 2008, Orlando, FL.
  58. D. Akopian, P. Chen, S. Miryakar, A. Kumar, “PreNotiS: Massive Preventive Notification System,” Proceeding of SPIE, Vol. 6982, pp. 69820Y-69820Y-8. Mobile Multimedia/Image Processing, Security, and Applications, March 2008, Orlando, FL.
  59. K. Naghdali, S. Dursun, D. Akopian, “Non-uniform pulse quantization for mutiplication-free correlation in ultra wideband receivers,” Proceeding of SPIE, Vol. 6980, pp. 698009-698009-7. Wireless Sensing and Processing III, March 2008, Orlando, FL.
  60. C. Lacatus, D. Akopian, M. Shadaram, “Fast convergence of distributed joint spreading sequence and power control algorithms,” 2008 IEEE Radio and Wireless Symposium, RWS, 22-24 Jan 2008, Orlando, FL.
  61. D. Akopian, P. Ybarra, P. Chen, “Optimization of time-varying two-band filterbanks for wavelet transforms,” Proceedings of IEEE SoSE 2007 Conference, April 16-18, 2007, San Antonio, TX.
  62. K. Naghdali, S. Dursun, D. Akopian, “Non-uniform pulse quantization for mutiplication-free correlation in ultra wideband receivers,” UTSA 2007 ESB Student Conference, Accepted to SPIE Defence and Security Conference, March 2008, Orlando, FL.
  63. A. Melkonyan, D. Akopian, P. Chen, “Impact Localization for Structural Health Monitoring,” UTSA 2007 ESB Student Conference, Nov 9, 2007.
  64. A. Panchul, D. Akopian, “Educational Applications Development for Smartphones,” UTSA 2007 ESB Student Conference, Nov 9, 2007, abstract accepted to 2008 ASEE Annual Conference, June 2008, Pittsburgh, PA
  65. H. Nguyen, T. Nguyen, R. Trevino, E. Teran-Delgado, A. Panchul, D. Akopian, “A case study of context-driven aspplication as an example of educational project on cell phone platforms,” UTSA 2007 ESB Student Conference, Nov 9, 2007.
  66.  Phani K. Sagiraju, Praveen Gali, David Akopian, G.V.S. Raju, “Enhancing Security in Wireless Networks Using Positioning Techniques,” Proceedings of IEEE SoSE 2007 Conference, San Antonio, TX, April 16 -18, 2007.
  67. Phani K. Sagiraju, Aleksandr Panchul, David Akopian, “A Software GPS+ Receiver Toolkit ” Proceedings of IEEE SoSE 2007 Conference, San Antonio, TX, April 16 -18, 2007.
  68. Phani K. Sagiraju, David Akopian, “Performance Study of Reduced Search FFT-Based Acquisition” Proceedings of ION National Technical Meeting, San Diego, California, January 22-24, 2007.
  69. C. Lacatus, D. Akopian, M. Shadaram, “Fast convergence of distributed joint spreading sequence and power control algorithms,” 2008 IEEE Radio and Wireless Symposium, RWS, 22-24 Jan 2008, Orlando, FL.
  70. C. Lacatus, D. Akopian, M. Shadaram, “An adaptive approach to compensate crosscorrelation effects in weak signal conditions for satellite positioning systems,” ION GNSS Conference, 26-28 Sep 2007, Fort Worth, TX.
  71. C. Lacatus, D. Akopian, M. Shadaram, “Spectrum assignment for flexible rate cognitive OFDM Systems,” 2007 IEEE MILCOM Conference, 29-31 Oct 2007, Orlando, FL
  72. C. Lacatus, D. Akopian, M. Shadaram, “Spreading sequence design for MC-CDMA systems,” IEEE International Conference on System of Systems Engineering, SoSE 2007, April 15-18, 2007, San Antonio, TX
  73. D. Bhupathiraju, D. Akopian, “Automatic Sorting and Storage Based on Location Information” ION NTM 2007, January2007.
  74. P. Sagiraju, H. Valio, D. Akopian,”Fine Frequency Estimation in Weak Signals for GPS Receivers” ION NTM 2006, January 18, Monterey, CA.
  75. P. Sagiraju, D. Akopian, “Performance of Two-Stage Massive Correlator Architecture for Fast Acquisition of GPS Signals” IEEE Region 5 Conference, April 2006, San Antonio, TX.
  76. A. Panchul, D. Akopian, “On porting computer applications into Symbian cell phone platform”, IEEE Region 5 Conference, April 2006, San Antonio, TX.
  77. A. Panchul, D. Bhupathiraju, S. Agaian, D. Akopian, “An imaging toolbox for smart phone applications”, Mobile Multimedia/Image Processing for Military and Security Applications, SPIE Defense and Security Symposium Symposium, 17-21 April 2006, Orlando, FL
  78. P. Sagiraju, D. Bhupathiraju, GVS Raju, D. Akopian, “Software GPS receiver test-bed development at UTSA” IEEE PLANS 2006.
  79. D. Bhupathiraju, P. Sagiraju, D. Akopian, “An automatic digital album,” IEEE WTS Conference, April 28-29, 2006, Pomona, CA.
  80. D. Akopian, S. Agaian, H. Valio, “Fast time-recursive matched filters for DSSS communications,” US Institute of Navigation, ION NTM 2006 Conference, January 2006.
  81. S. Agaian, D. Akopian and S. D’Souza “Wireless Steganography” SPIE Electronic imaging Conference, January 2006.
  82. D. Akopian and S. Agaian, “A Fast position recovery approach for GPS receivers in jamming environments and a recommendation for future GPS signal structure,” IEEE MILCOM Conference, Atlantic City, Oct. 17-21, 2005.
  83. Phani K. Sagiraju, David Akopian and David Magee “A Fast Acquisition Algorithm for Indoor Receivers”, US Institute of Navigation (ION), 61st Annual Meeting, June 2005.
  84. D. Akopian, Phani K. Sagiraju, S. Agaian, G.V.S. Raju, “A Reduced complexity frequency domain acquisition of DS-SS Signals for embedded applications,” IS&T/SPIE’s Symposium on Electronic Imaging: Science & Technology, Jan. 2005.
  85. D. Akopian, S. Agaian, Fast and Parallel matched filters in time domain,” US Institute of Navigation, GNSS’ 2004 Conference, September 21-24, 2004, Long Beach, CA, USA
  86. D. Akopian, S. Agaian, “A fast algorithm for long FIR filters with small coefficient alphabet”, The 2004 Int. Workshop on Spectral Methods and Multirate Signal Processing, SMMSP2004, September 11-12, 2004, Vienna, Austria.
  87. C.B. Smith, D. Akopian, S. Agaian, ” Least squares optimization of a polynomial threshold for wavelet domain denoising”, Proceedings of ICSP’04 7th Internatiuonal Conference on Signal Processing, 31 Aug.-4 Sept. 2004, Vol. 1, pp. 109-112.
  88. D. Akopian, S. Agaian, “Fast matched filter in time domain”, IEEE Position Location and Navigation Symposium 2004, April 26-29, Monterey, CA, 2004, pp. 455-460
  89. D. Akopian, J. Takala, S. Agaian, “Scalable transform accelerator for multimedia communications”, SPIE Electronic Imaging/ Embedded Processors for Multimedia and Communications Conference, January 2004, SPIE Vol. 5309, pp. 70 – 79.
  90. D. Akopian, J. Syrjärinne, “A Network aided iterated LS method for GPS positioning and time recovery without navigation message,” Proceedings of IEEE PLANS’2002 Conference, April 15-18, 2002, Palm Springs, CA, USA, pp. 77-83.
  91. D. Akopian, H. Valio, S. Turunen, “Fine acquisition methods for GPS receivers,” ION GPS’ 2002 Conference, US Institute of Navigation, September 24-27, 2002, Portland, Oregon, USA.
  92. D. Akopian, “Backpropagation optimization algorithm for families of linear-phase filterbanks and block transforms”, Proceedings of CSIT’ 2001 Conference, Yerevan, Armenia, Sept. 17-20, 2001
  93. D. Akopian, “An optimization approach for two-band periodically time-varying perfect reconstruction filterbanks”, Proceedings of CSIT’2001 Conference, Yerevan, Armenia, Sept. 17-20, 2001.
  94. D. Akopian, “A fast satellite acquisition method”, USA Institute of Navigation, ION-GPS’2001Conference, Salt Lake City, USA, Sept. 11-14, 2001.
  95. D. Akopian, J. Parkkinen, T. Jääskeläinen, and J. Astola: Multibase Transform Coding for Multispectral Image Compression. In Proceedings of Algorithms for Multispectral, Hyperspectral, and Ultraspectral Imagery VI, SPIE vol. 4049, Orlando, USA, April 24-26, 2000, pp. 511-520.
  96. J. Nikara, J. Takala, D. Akopian, J. Saarinen, J. Astola, “Pipelined architecture for inverse Discrete Cosine Transform,” Proceedings of EUSIPCO’2000 Conference, Tampere, Finland
  97. K. Balashov, D. Akopian, J. Astola, “Lossless Compression of Natural Images Using Regressive Analysis,” Proceedings of EUSIPCO’2000 Conference, Tampere, Finland
  98. J. Takala, J. Nikara, D. Akopian, J. Astola, and J. Saarinen, “Pipeline Architecture for 2-D 8×8 Discrete Cosine Transform,” in Proc. IEEE Int.Conf. on Acoustics, Speech and Signal Process., Istanbul, Turkey, June 5-9, 2000, vol. VI, pp. 3303-3306.
  99. J. Takala, D. Akopian, J. Astola, and J. Saarinen, “Scalable Interconnection Networks for Partial Column Array Processor Architectures,” in Proc. IEEE Int. Symp. on Circuits and Systems, Geneva, Switzerland, May 28 – 31 2000, vol. IV, pp. 513-516.
  100. J. Takala, T.S. Jarvinen, P.V. Salmela, D. Akopian, “Multi-port interconnection networks for radix-R algorithms”. Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing, 2001 (ICASSP ’01). Volume 2, 7-11 May 2001 Page(s):1177 – 1180 vol.2
  101.   J. Nikara, J. Takala, D. Akopian, and J. Saarinen, “Pipeline Architecture for DCT/IDCT” in Proc. of 2001 IEEE International Symposium on Circuits and Systems, 2001. ISCAS 2001. Volume 4, 6-9 May 2001, pp. 902 – 905.
  102.    D. Akopian and J. Astola, “An optimal bit-allocation technique for multibase transforms,” Proceedings of FINSIG’99 Conference, 1999, Oulu, Finland
  103.   . Tunyan, J. Astola, D. Akopian, A. Tuniev, “Development of A-orthogonalization process and its possible applications,” Proceedings of the Conference, Computer Science and Information Technologies (CSIT’99), Yerevan, Armenia, pp. 321-324, 1999.
  104.    D. Akopian and J. Astola, “Multibase transform with prediction for still image compression,” Proceedings of the Conference, Computer Science and Information Technologies (CSIT’99) Yerevan, Armenia, 1999.
  105.    D. Akopian, M. Helsingius, J. Astola, “An Optimized Multiscanning Approach for Still Image Compression,” 1999 IEEE International Workshop on Multimedia Signal Processing (MMSP’99), September 13-15, 1999, Copenhagen, Denmark
  106.    D. Akopian, J. Takala, J. Astola, J. Saarinen, “Multistage interconnection networks for k/n rate Viterbi decoders,” IEEE GLOBECOM’98 Conference, Nov., Australia, 1998.
  107.    D. Akopian, M. Helsingius, J. Astola, “A Combined multibase/wavelet transform coding of still images,” Proceedings of IEEE ISPACS’98 Conference, 1998.
  108.    D. Akopian and J. Astola, “Fast architecture oriented algorithms for trigonometric transforms and their mapping to scalable structures,” Proceedings of First International Workshop on Transforms and Filterbanks, TICSP Series-1, June 1998, pp. 433-471.
  109.    D. Akopian, M. Helsingius, J. Astola, “Multibase/Wavelet transform coding without blocking artifacts,” Proceedings of 32nd Asilomar Conference on Signals, Systems, and Computers, November 1-4, 1998, Pacific Grove, CA, USA.
  110.   D. Akopian, J. Takala, J. Astola, J. Saarinen, “A Multistage interconnection network for parallel Viterbi decoders,” Proceedings of IEEE ISPACS’97 Conference, 11-13 Nov., Malaysia, pp. S16.6.1-S16.6.5, and FINSIG’97 Conference, May 22, Pori, Finland, 1997.
  111.    D. Akopian and J. Astola, “An optimal nonlinear extension of linear filters,” Proc. of CSIT’97 Conference, 26-29 Sept., 1997, Yerevan, Armenia, pp. 141-144.
  112.    D. Akopian and J. Astola, “An optimal extension of linear filters based on distributed arithmetic,” Proc. of SPIE Statistical and Stochastic Methods in Image Processing II Conference, 27 July-1 August, 1997, San Diego, CA.
  113.    J. Astola and D. Akopian, “Fast regular 2-D algorithms for a class of trigonometric transforms,” Proc. of IS\&T/SPIE’s Symp. on Electronic Imaging, Sc. and Technology, Visual Com. and Image Proc., February, 1997.
  114.    O. Vainio, D. Akopian, J. Astola, “A Synthesizable stack filter ASIC macro,” Proc. of IEEE Int. NORCHIP’96 Conference, pp. 172-178, November 1996.
  115.    M. Helsingius, S. Atourian, D. Akopian and J. Astola, “Multibase transform coding of images,” Proc. of IEEE Int. NORSIG’96 Conference, pp. 255-258, September 1996.
  116.    D. Akopian and J. Astola,”Processor architecture for Extended Lapped Transform,” Proc. of EUSIPCO’96 Conference, pp. 1459-1462, 1996.
  117.    I. Dhaou, D. Akopian, P. Kuosmanen and J. Astola, “Fault detection in stack filters based on sample selection probabilities,” Proc. of IEEE Int. Conf. on Image Processing, pp. 765-768, 1996.
  118.   D. Akopian and J. Astola, “Pipeline processor for fast architecture oriented regular DCT-IDCT algorithm,” Proc. of IEEE Int. Conf. on Acoust. Speech and Sign. Processing, pp.1319-1322, May 1996, Atlanta, USA.
  119.    J. Astola and D. Akopian, “Architecture oriented regular algorithms for discrete sine and cosine transforms,” Proc. of IS\&T/SPIE’s Symp. on Electronic Imaging, Sc. and Technology, pp. 9-20, 28 Jan.-2 Feb., 1996
  120.    J. Astola, P. Kuosmanen, D. Akopian, D. Gevorkian, “Fibonacci P-Code method for generalized stack filtering,” Proc. of IEEE Int. Symp. on Circuits and Systems, pp. 1900-1903, 1995.
  121.    Jaakko Astola, David Akopian, and Karen Egiazarian, “New processor architecture for running threshold Boolean filters,” Proc. of SPIE Meeting on Visual Communications and Image Processing’95, pp. 366-377, Taiwan, May 1995.
  122.    Karen Egiazarian, David Akopian, and David Gevorkian, “Threshold Boolean filtering based on pattern classification,” Proc. of IEEE Workshop on Nonlinear Signal and Image Processing, pp. 879-882, June 1995, Greece.
  123.    O. Vainio, D. Akopian, J. Astola, “Systematic design of encoder and decoder networks with applications to high-speed signal processing,” Proc. of IEEE Int. Symp. on Industrial Electronics, Athens, Greece, July 1995, pp. 172-175.
  124.    J. Astola, D. Akopian, S. Agaian, O. Vainio, “A Unified approach to implementation of stack filters,” Proc. Of Twenty-Eight Asilomar Conf. on Signals, Systems and Computers, Nov. 1-3, pp. 329-334, 1994, Pacific Grove, California.
  125.    D. Akopian, O. Vainio, S. Agaian, and J. Astola, “SBNR processor for stack filters,” Proc. of Twenty-Eight Asil. Conf. on Signals, Systems and Computers, pp. 335-339, Nov. 1-3, 1994.
  126.    D. Akopian, K. Egiazarian, S. Agaian, J. Astola, “Pipeline processors for fast trigonometric transforms,” Proc. of Twenty-Eight Asilomar Conf. on Signals, Systems and Computers, pp. 1031-1035, Nov. 1-3, 1994, Pacific Grove, California.
  127.    S. Agaian and D. Akopian, “Fibonacci processors for digital signals transform,” Proc. of First USSR Conf. on Pattern Recognition and Image Analyses: New informative technologies (ROAI-1-91), Part III, Section 3, pp. 13-15, Minsk (USSR), October 14-18, 1991.
  128.    D. Akopian and J. Astola, “Pipeline processor for DCT-IDCT algorithm,” Proc. of FINSIG’95 Conf., 1995.
  129.    D. Akopian, O. Vainio, J. Astola, “Parallel multi-threshold circuit and stacked signals adder,” Proceedings of the First TUT Symposium on Signal Processing, pp. 23-26, May 20, 1994.