Question

A 1024-bit message is sent that contains 992 data bits and 32 CRC bits. CRC is computed using the IEEE 802 standardized, 32-degree CRC polynomial. For each of the following, explain whether the errors during message transmission will be detected by the receiver: (a) There was a single-bit error. (b) There were two isolated bit errors. (c) There were 18 isolated bit errors. (d) There were 47 isolated bit errors. (e) There was a 24-bit long burst error. (f) There was a 35-bit long burst error.

Answer 1

Answer:

a) Yes

b) Yes

c) Yes

d) No

e) Yes

f) No

Explanation:

a) All single-bit errors  are caught by Cyclic Redundancy Check (CRC) and it produces 100 % of error detection.

b) All double-bit errors for any reasonably long message  are caught by Cyclic Redundancy Check (CRC) during the transmission of 1024 bit. It also produces 100 % of error detection.

c) 5 isolated bit errors  are not caught by Cyclic Redundancy Check (CRC) during the transmission of 1024 bit since CRC may not be able to catch all even numbers of isolated bit errors so it is not even.

It produces nearly 100 % of error detection.

d) All even numbers of isolated bit errors may not be caught by Cyclic Redundancy Check (CRC) during the transmission of 1024 bit. It also produces 100 % of error detection.

e) All burst errors with burst lengths less than or equal to 32 are caught by Cyclic Redundancy Check (CRC) during the transmission of 1024 bit. It also produces 100 % of error detection.

f) A burst error with burst length greater than 32 may not be caught by Cyclic Redundancy Check (CRC) during the transmission of 1024 bit.

Cyclic Redundancy Check (CRC) does not detect the length of error burst which is greater than or equal to r bits.