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An overview of the basic concepts of error detection and correction in data communication networks. It covers the types of errors that can occur during data transmission, including single-bit errors and burst errors. The document then discusses various error detection techniques such as vertical redundancy check (vrc), longitudinal redundancy check (lrc), and cyclic redundancy check (crc). It also explains the concept of checksum and how it can be used for error detection. Additionally, the document covers error correction methods, including single-bit error correction and the hamming code. The information presented in this document can be useful for students and professionals studying or working in the field of data communication and networking.
Typology: Summaries
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Networks must be able to transfer data from
one device to another with complete accuracy.
Data can be corrupted during transmission.
For reliable communication, errors must be
detected and corrected.
at the data link layer or the
transport layer of the OSI model.
Single bit errors are the least likely type of
errors in serial data transmission because
the noise must have a very short duration
which is very rare. However this kind of
errors can happen in parallel transmission.
Burst error
The term burst errorburst error means that two or
more bits in the data unit have changed
from 1 to 0 or from 0 to 1.
Burst errors does not necessarily mean that
the errors occur in consecutive bits , the
length of the burst is measured from the
first corrupted bit to the last corrupted bit.
Some bits in between may not have been
corrupted.
Burst error is most likely to happen in serial
transmission since the duration of noise is
normally longer than the duration of a bit.
The number of bits affected depends on the data
rate and duration of noise.
Redundancy
Four types of redundancy checks are usedFour types of redundancy checks are used
in data communications in data communications
It can detect burst errors only if the total
number of errors is odd.
LCR increases the likelihood of detecting
burst errors.
If two bits in one data units are damaged
and two bits in exactly the same positions in
another data unit are also damaged, the
LRC checker will not detect an error.
the message because these redundant bits only will enable the receiver to
detect whether there is an error or not.
redundant bits. In this technique , these redundant bits are called CRC.
divisor, so the divisor will be known to the sender and receiver, so
based on divisor CRC will be calculated.
E.g: if the length of the divisor is 5 , then we are going to
append 4 zeros to the original message.
results, one is quotient and second is remainder.
