I did research in this area last decade, and I'm one of the authors of a survey paper that you might find useful if this subject is interesting to you: http://u

I did research in this area last decade, and I'm one of the authors of a survey paper that you might find useful if this subject is interesting to you: http://utopia.csis.pace.edu/dps/2007/jkile/content/2005-fall/DCS860A/Extra%20Credit/Original%20papers/j5040.pdf http://utopia.csis.pace.edu/dps/2007/jkile/content/2005-fall... There is research stretching back 30 years in this area. Some of the results are very promising, but the field is severely encumbered with patents. I was even threatened with a cease-and-desist while doing a research project in this area for a graduate class.