[HW] HW08 2020

[Prof. Hsiao]

True (select A in the homework system) or false (B). 

 

Q. If two-dimensional even parity is used, complete the following table (R1~R5, C1~C6 and X).

1 1 0 1 0 1 | R1 = 0

0 1 0 1 1 1 | R2 = 0

0 1 1 1 0 0 | R3 = 1

1 0 1 0 0 0 | R4 = 0

1 1 0 0 1 0 | R5 = 1

--------------------------

1 0 0 1 0 0 | X = 0

Q1. R1 is 1. 

B. False.

Q2. R2 is 1.

B. False.

Q3. C1+C2+C3+C4+C5+C6 = R1+R2+R3+R4+R5

A. True. 2.

Q4. C3 is 1.

B. False.

Q5. C4 is 1.

A. True.

Q6. X is 1.

B. False.

 

Q7. Considering CRC error checking, if data D = 11100101 and the generator G = 11011, what is the CRC bits?

A. 1000;  B. 0100;  C. 0010; D. 0001;  E. 0000;

B. 111001010000 div 11011 

 

Q8. In CSMA/CD, after the 4th collision, what is the probability that a node chooses K = 2?

  A. 1/5; B. 1/8; C. 1/16; D. 1/32; E. 1/64

C. 2^4 = 16, K={0, 1, 2, 3, 4, …, 15}, Prob{k=2}=1/16