UNIT 3
ERROR DETECTION, CORRECTION AND COMMUNICATION
Types of network errors - Error detection- Error correction methods -Flow
control -Error control -IEEE 802.3-- IEEE 802.5 -IEEE 802.11 -IEEE
802.15.1 (Piconet and Scatternet).
3.1 Types of network errors
1. Single-bit Error
A single-bit error happens when only one bit in a data unit is incorrectly changed during
transmission. This means that a bit with value 0 may become 1, or a 1 may become 0. For example,
if the sender transmits the data 10101100, and the receiver gets 10111100, it means the third bit from
the left has changed from 0 to 1. These types of errors are usually caused by minor electrical
disturbances or noise on the transmission medium. Single-bit errors are relatively rare in modern
communication systems that use optical fiber or twisted pair cables, but they are easy to detect
and correct using methods like parity bits or Hamming codes.
A single-bit error refers to a type of data transmission error that occurs when one bit (i.e., a single
binary digit) of a transmitted data unit is altered during transmission, resulting in an incorrect or
corrupted data unit.
Single-Bit Error
A single-bit error happens when only one bit in a data unit is incorrectly changed during
transmission. This means that a bit with value 0 may become 1, or a 1 may become 0. For example,
if the sender transmits the data 10101100, and the receiver gets 10111100, it means the third bit from
the left has changed from 0 to 1. These types of errors are usually caused by minor electrical
disturbances or noise on the transmission medium. Single-bit errors are relatively rare in modern
,communication systems that use optical fiber or twisted pair cables, but they are easy to detect
and correct using methods like parity bits or Hamming codes.
Multiple-Bit Error
A multiple-bit error is an error type that arises when more than one bit in a data transmission is
affected. Although multiple-bit errors are relatively rare when compared to single-bit errors, they
can still occur, particularly in high-noise or high-interference digital environments.
Multiple-Bit Error
A multiple-bit error is a type of transmission error that arises when two or more bits in a data unit
are altered during transmission. These errors can result from various factors such as
electromagnetic interference, voltage spikes, hardware failures, or burst noise in the
communication medium. Although multiple-bit errors are relatively less common than single-bit
errors, they pose a greater threat to data integrity because they can significantly distort the original
information. Simple error detection methods like parity checks are often ineffective against such
errors. As a result, systems exposed to high-noise environments rely on robust error control
techniques such as Cyclic Redundancy Check (CRC), Reed-Solomon codes, or Forward Error
Correction (FEC) to ensure accurate and reliable data communication.
Burst Error
When several consecutive bits are flipped mistakenly in digital transmission, it creates a burst error.
This error causes a sequence of consecutive incorrect values.
, Burst Error
A burst error occurs in digital communication when two or more consecutive bits in a transmitted
data stream are altered due to noise or interference. Unlike single-bit errors, which affect isolated
bits, burst errors involve a sequence of bits—from a few to hundreds—being flipped incorrectly
during transmission. These errors are commonly caused by channel noise, lightning strikes, signal
distortion, or equipment malfunctions and are more likely to occur in serial data transmission.
The length of a burst error is measured from the first bit in error to the last bit in error,
including any correct bits in between. Burst errors are especially dangerous because they may affect
entire words or packets, leading to data corruption.
Simple techniques like parity may fail to detect or locate burst errors. Therefore, robust error
detection and correction mechanisms such as Cyclic Redundancy Check (CRC), Reed-
Solomon codes, and interleaving are used to detect and correct them. These methods are capable
of breaking a burst error into multiple detectable single-bit errors, enhancing the reliability of
communication systems.
, 3.2 Error Detection
Error is a condition when the receiver's information does not match the sender's. Digital signals
suffer from noise during transmission that can introduce errors in the binary bits traveling from
sender to receiver. That means a 0 bit may change to 1 or a 1 bit may change to 0.
Data (Implemented either at the Data link layer or Transport Layer of the OSI Model) may get
scrambled by noise or get corrupted whenever a message is transmitted. To prevent such errors,
error-detection codes are added as extra data to digital messages. This helps in detecting any errors
that may have occurred during message transmission.
Error Detection Methods
To detect errors, a common technique is to introduce redundancy bits that provide additional
information. Various techniques for error detection include:
1. Simple Parity Check
2. Two-Dimensional Parity Check
3. Checksum
4. Cyclic Redundancy Check (CRC)
3.2.1 Simple Parity Check
Simple-bit parity is a simple error detection method that involves adding an extra bit to a data
transmission. It works as:
1 is added to the block if it contains an odd number of 1’s,
1 is added to the block if it contains an odd number of 1’s, and
0 is added if it contains an even number of 1’s
This scheme makes the total number of 1’s even, that is why it is called even parity checking.
ERROR DETECTION, CORRECTION AND COMMUNICATION
Types of network errors - Error detection- Error correction methods -Flow
control -Error control -IEEE 802.3-- IEEE 802.5 -IEEE 802.11 -IEEE
802.15.1 (Piconet and Scatternet).
3.1 Types of network errors
1. Single-bit Error
A single-bit error happens when only one bit in a data unit is incorrectly changed during
transmission. This means that a bit with value 0 may become 1, or a 1 may become 0. For example,
if the sender transmits the data 10101100, and the receiver gets 10111100, it means the third bit from
the left has changed from 0 to 1. These types of errors are usually caused by minor electrical
disturbances or noise on the transmission medium. Single-bit errors are relatively rare in modern
communication systems that use optical fiber or twisted pair cables, but they are easy to detect
and correct using methods like parity bits or Hamming codes.
A single-bit error refers to a type of data transmission error that occurs when one bit (i.e., a single
binary digit) of a transmitted data unit is altered during transmission, resulting in an incorrect or
corrupted data unit.
Single-Bit Error
A single-bit error happens when only one bit in a data unit is incorrectly changed during
transmission. This means that a bit with value 0 may become 1, or a 1 may become 0. For example,
if the sender transmits the data 10101100, and the receiver gets 10111100, it means the third bit from
the left has changed from 0 to 1. These types of errors are usually caused by minor electrical
disturbances or noise on the transmission medium. Single-bit errors are relatively rare in modern
,communication systems that use optical fiber or twisted pair cables, but they are easy to detect
and correct using methods like parity bits or Hamming codes.
Multiple-Bit Error
A multiple-bit error is an error type that arises when more than one bit in a data transmission is
affected. Although multiple-bit errors are relatively rare when compared to single-bit errors, they
can still occur, particularly in high-noise or high-interference digital environments.
Multiple-Bit Error
A multiple-bit error is a type of transmission error that arises when two or more bits in a data unit
are altered during transmission. These errors can result from various factors such as
electromagnetic interference, voltage spikes, hardware failures, or burst noise in the
communication medium. Although multiple-bit errors are relatively less common than single-bit
errors, they pose a greater threat to data integrity because they can significantly distort the original
information. Simple error detection methods like parity checks are often ineffective against such
errors. As a result, systems exposed to high-noise environments rely on robust error control
techniques such as Cyclic Redundancy Check (CRC), Reed-Solomon codes, or Forward Error
Correction (FEC) to ensure accurate and reliable data communication.
Burst Error
When several consecutive bits are flipped mistakenly in digital transmission, it creates a burst error.
This error causes a sequence of consecutive incorrect values.
, Burst Error
A burst error occurs in digital communication when two or more consecutive bits in a transmitted
data stream are altered due to noise or interference. Unlike single-bit errors, which affect isolated
bits, burst errors involve a sequence of bits—from a few to hundreds—being flipped incorrectly
during transmission. These errors are commonly caused by channel noise, lightning strikes, signal
distortion, or equipment malfunctions and are more likely to occur in serial data transmission.
The length of a burst error is measured from the first bit in error to the last bit in error,
including any correct bits in between. Burst errors are especially dangerous because they may affect
entire words or packets, leading to data corruption.
Simple techniques like parity may fail to detect or locate burst errors. Therefore, robust error
detection and correction mechanisms such as Cyclic Redundancy Check (CRC), Reed-
Solomon codes, and interleaving are used to detect and correct them. These methods are capable
of breaking a burst error into multiple detectable single-bit errors, enhancing the reliability of
communication systems.
, 3.2 Error Detection
Error is a condition when the receiver's information does not match the sender's. Digital signals
suffer from noise during transmission that can introduce errors in the binary bits traveling from
sender to receiver. That means a 0 bit may change to 1 or a 1 bit may change to 0.
Data (Implemented either at the Data link layer or Transport Layer of the OSI Model) may get
scrambled by noise or get corrupted whenever a message is transmitted. To prevent such errors,
error-detection codes are added as extra data to digital messages. This helps in detecting any errors
that may have occurred during message transmission.
Error Detection Methods
To detect errors, a common technique is to introduce redundancy bits that provide additional
information. Various techniques for error detection include:
1. Simple Parity Check
2. Two-Dimensional Parity Check
3. Checksum
4. Cyclic Redundancy Check (CRC)
3.2.1 Simple Parity Check
Simple-bit parity is a simple error detection method that involves adding an extra bit to a data
transmission. It works as:
1 is added to the block if it contains an odd number of 1’s,
1 is added to the block if it contains an odd number of 1’s, and
0 is added if it contains an even number of 1’s
This scheme makes the total number of 1’s even, that is why it is called even parity checking.
