tailieunhanh - Lecture Digital communication systems - Lecture 9

In this chapter we will discuss: History, sound recording in the digital age, defining features of sound recording, organization of the recording industry, ownership in the recording industry, producing records, making a CD, economics, feedback, the recording industry. | DIGITAL COMMUNICATION SUSTEMS Fall 2012 Lecture 9 A small postscript on multiple random variables Introduction to modulation and demodulation Input output descriptions of systems Linear time-invariant LTI models Fall 2012 Lecture 9 Slide 1 Dealing with Multiple Random Variables PDF of a random variable X fX x 0 and f fX x dx 1 this integral is over the entire real line The natural extension to the case of two random variables X and Y is the joint PDF of X and Y fXY x y 0 and i fXY x y dx dy 1 2D-integral covers the entire x y plane Expected value of a function of X Y E g X Y ff g x y fx Y x y dx dy And similarly for more random variables Fall 2012 Lecture 9 Slide 2 In our Signal Detection Setting Last lecture we discussed averaging multiple random variables A w 1 w 2 . w M M and wanted the mean and variance of A. Here each w n was the additive noise component of a received sample in a fixed bit slot and assumed to be a zero-mean Gaussian of variance Ơ2 independent of all other w . . These w . constitute additive white Gaussian noise AWGN --- white here zero-mean iid Strictly speaking we should have been working with the joint PDF of the M random variables in an M-dimensional space. However the following facts suffice to get us through with just 1D PDFs Fall 2012 Lecture 9 Slide

• Kĩ thuật Viễn thông
• Communication systems
• Digital communication systems
• Digital communication
• Multiuser communication
• Multicarrier system
• Adaptive equalization
• Filter channel
• communication systems research
• communication applications
• electronic media
• communication solutions
• systems management