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lecture26

# lecture26 - Lecture Outline(Week 15 lecture 1 Review of...

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Lecture Outline (Week 15, lecture 1) Review of Digital Communication Reading: Focus on these notes. 1. Basic Elements of Digital Communication Basic block diagram of a digital communication system. Basic equation governing source: Nyquist sampling and entropy rate of source ) ( X H R = Basic equation governing channel: Shannon’s formula ) 1 ( log 0 2 W N P W C + = (Bits/sec) Channel: Power and interference budgets. Channel impairments. Multiple access. 2. Elements of Source Encoding Digitizing of an analog source includes: Sampling at twice the highest frequency of signal, i.e. W T f s 2 / 1 = . Nyquist sampling theorem, signal can reconstructed by - - = n nT t T nT t T nT x t x ) ( 1 )) ( 1 sin( ) ( ) ( ~ Quantizing samples into v bits with quantization error for uniform quantization: 8 . 4 02 . 6 ] [ log 10 2 10 + + = v X E SQNR dB where max x X X = May use non-uniform quantizer such as μ -law compander. After digitization, we perform data compression: Universal data compression such as Lempel-Ziv codes Optimal Huffman Codes achieves close to ) ( X H R = 1

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3. Modulation Techniques and Signal Space Representation. Digital modulation techniques: Pulse Amplitude Modulation(PAM) -∞ = - = n n nT t h a t x ) ( ) ( , 4PAM: } 3 , , , 3 { A A A A a n + + - -
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• Spring '09
• Hui
• signal space, Signal Space Representation. • Digital, signal point, dB more signal, Signal Space Representation.

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lecture26 - Lecture Outline(Week 15 lecture 1 Review of...

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