# hw7s - ECE 178 HW#7 Solutions Anindya Sarkar Emre Sargin Q1...

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ECE 178: HW #7 Solutions Q1 . a) H ( X ) = 4 × 1 / 32 × log 2 (32)+2 × 1 / 16 × log 2 (16)+8 × 1 / 64 × log 2 (64)+1 / 8 × log 2 (8)+1 / 2 × log 2 (2) H ( X ) = 22 / 8bits b) Entropy maximizing distribution is the uniform distribution: p i = 1 / 16 , i = 1 ,..., 16 c) Proof. H ( X ) = X i p i log 2 ( 1 p i ) |{z} Jensen log 2 ( X i p i 1 p i ) = log 2 ( |X| ) Equality holds only if p i = 1 / |X| ∀ i , which completes the proof. 1

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Q2 . Huﬀman code can be constructed as follows: Message Probability a 1 2 15 a 2 2 15 a 3 3 15 a 4 3 15 a 5 5 15 Message Probability a 3 3 15 a 4 3 15 a 5 5 15 a 6 = { a 1 ,a 2 } 4 15 Message Probability a 7 = { a 3 ,a 4 } 6 15 a 5 5 15 a 6 = { a 1 ,a 2 } 4 15 Message Probability a 7 = { a 3 ,a 4 } 6 15 a 8 = { a 5 ,a 6 } 9 15 Message Probability Codeword a 1 2 15 100 a 2 2 15 101 a 3 3 15 00 a 4 3 15 01 a 5 5 15 11 2
Q3 . Message is in between (0 . 931878 , 0 . 931905) 0 a 1 2/15 a 2 4/15 a 3 7/15 a 4 10/5 a 5 1 0.000000 0.133333 0.266667 0.466667 0.666667 1.000000 0.666667 0.711111 0.755556 0.822222 0.888889 1.000000 0.888889 0.903704 0.918519 0.940741 0.962963 1.000000 0.918519 0.921481 0.924444 0.928889 0.933333 0.940741 0.928889 0.929481 0.930074 0.930963 0.931852 0.933333 0.931852 0.932049 0.932247 0.932543 0.932840 0.933333 0.931852 0.931878 0.931905 0.931944 0.931984 0.932049 3

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Q4 . Figure 1: A lossy open-loop predictive coding model: (a) encoder and (b) decoder e n = f n - ˆ f n , where in HW problem ˆ f n = f n - 1 In the decoder side, the bit-sequence (of the prediction error) is decoded to obtain the error terms (let ˙ e n denote the quantized version of e n , as in Fig. 1). The reconstructed output ˙ f n is obtained by adding the quantized error to the predicted value ˆ f n . ˙ f
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## This note was uploaded on 06/12/2009 for the course ECE 178 taught by Professor Manjunath during the Winter '08 term at UCSB.

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hw7s - ECE 178 HW#7 Solutions Anindya Sarkar Emre Sargin Q1...

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