# a4 - CSE 489/589 Homework Assignment 4 Due at the end of...

This preview shows pages 1–2. Sign up to view the full content.

CSE 489/589 Homework Assignment 4 Due at the end of class on Wed, Dec 08. * November 23, 2010 Problem 1. Recall that the CRC code allows us to compute the redundancy string R to be appended to the data string D given the generator string G . (a) Suppose D = 111010101100 and G = 10011 . What is R as a binary string? Show your work using the polynomial division method I’ve shown in class. (b) Show that the CRC code can detect any odd number of bit errors if the generator polynomial G ( x ) contains a factor ( x + 1) . (In practice, the CRC-1 code uses G ( x ) = x + 1 itself. The CRC-12 code used in some telecom systems uses G ( x ) = x 12 + x 11 + x 3 + x 2 + x + 1 = ( x + 1)( x 11 + x 2 + 1) which has a ( x + 1) -factor.) Problem 2. Consider the Clos fabric design C (3 , 3 , 2) shown in figure 2. We have shown in class that Figure 1: The Clos network C (3 , 3 , 2) the network is rearrangeably non-blocking (RNB) because m = n = 3 in this case. RNB means every valid 1-1 mapping from inputs to outputs can be realized. RNB also means that a new request from a free input to a free output can always be routed through the fabric if we are allowed to rearrange existing routes. Instructor HN thinks that, perhaps, if the algorithm for finding routes is smarter then we might

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern