Using Government drawings, specifications, or other data included in this document for any purpose other than Government procurement does not in any way obligate the U.S. Government. The fact that the Government formulated or supplied the drawings, specifications, or other data does not license the holder or any other person or corporation; or convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report was cleared for public release by the 88 th ABW, Wright-Patterson AFB Public Affairs Office and is available to the general public, including foreign nationals. Copies may be obtained from the Defense Technical Information Center (DTIC) (http://www.dtic.mil).
The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSOR/MONITOR'S ACRONYM(S)AFRL/RI SPONSORING/MONITORING AGENCY REPORT NUMBER AFRL-RI-RS-TR-2014-093 DISTRIBUTION AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited. PA# 88ABW-2014-1899 Date Cleared: 23 Apr 2014 SUPPLEMENTARY NOTES ABSTRACTThis final report summarizes the most significant findings of the work done under the in-house effort titled "Optimal Methods for Modulation Classification" on average likelihood methods. The development began with the exact calculation of the likelihood function using symbolic algebra software. After investigating its properties, it was possible to develop formulas for more general cases. The solution of the likelihood function depends on a joint probability of the spreading code coefficients/elements. Simplification of the likelihood was achieved using the invariance properties of the Total Squared Correlation to permutations. The average likelihood can be expressed as sum of a product of hyperbolic cosine functions. Most these terms vanish after adjusting precision parameter from the joint probability of the code matrix. For a full loaded CDMA signal, the average likelihood depends exclusively on feature vectors or the absolute value of the sum of the columns of the matrix with the lowest Total Square Correlation. The ROC curves were plotted for characterizing the performance of the classifier.
This report summarizes the work done under the in-house effort titled "Optimal Methods for Modulation Classification." The effort revisited the problem of blind demodulation for develop classification algorithms for wider set of signals types. Two methodologies were used: Likelihood Ratio Test and inference methods using Expectation Maximization. A simple case of the likelihood was developed for spread spectrum. Also a minimum divergence approach was developed for classifying MPSK and QAM. Future work will refine these two proposed concepts. Finally, this research explored MIMO codes design. The purpose was to design codes that exceeded the performance of the Full-Rate, Full Diversity Golden Codes. It was possible to find linear codes with higher spectral rate, but also higher average power. This concepts will be refined as part of future work.
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