Assignment5

**CHAROTAR INSTITUTE OF TECHNOLOGY, CHANGA**

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**Sub:** DCN-I

**Assignment5:** *Error Detection and Correction*

**Class:** 4CE2

**Last Date: **21/3/07

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**Que: 1 Short Question:**

- What are the difference between packet errors and bit errors?
- What are even and odd parity?
- What is the difference in between a single bit error and a burst error?
- What are the different types of redundancy checks used in data communication?
- What kind of error VRC can detect?
- What is LRC?
- Is CRC superior to LRC? Why?
- What is an error syndrome?
- Which error detection method uses one’s complement arithmetic?
- Which error detection method consists of just one redundant bit per data?
- Which error detection method involves polynomials?
- Let a protection switch on a D53
*(45 Mbps)*takes 10ms to complete. What is the worst case error burst length? - In cyclic redundancy checking, the CRC is ______. [the divisor, the quotient, the dividend, the remainder]
- Hamming code is a method of
**_____**. [error detection, error correction, both] - CRC can detect all burst of up to m errors, if generator polynomial
*G(x)*is of ___ degree.*[m, m-1, m+1, one]* - Find the binary equivalent of

x^{8 }+ x^{3 }+ x +1

- If a divisor is 101101, how many bits long is the CRC.
- Find the polynomial equivalent of 100001110001.
- Find the complement of 1110010001110011
- Error detection is usually done in the ____ layer of the OSI model.
*[Physical, Data link, Network].*

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**Que: 2 Give answer:**

- Calculate the VRC and LRC for the following bit pattern using even parity.

0011101 1100111 1111111 0000000 **[May 2004]**

- Given a 10-bit sequence 1010011110 and a divisor of 1011, find the CRC. Check your answer.
- Discuss VRC and LRC mechanism for error detection.
**[May 2005]** - Generate CRC code for the data 11001 with divisor 1001. Also perform CRC checking procedure.
**[ May 2005]** - Construct the Hamming Code for the bit sequence 10011101
- The code 11110101101 was received. Using the Hamming encoding algorithm, what is the original code sent?
- A receiver receives the code 11001100111. When it uses the Hamming encoding algorithm, the result is 0101. Which bit is in error? What is the correct code?
- What kind of error is undetected by checksum?
- What is the formula to calculate the number of redundancy bits required to correct a bit error in a given number of data bits?
- What are the conditions for the polynomial used by CRC generator?