Error Coding Forward Error Coding FEC control errors

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Error Coding

Error Coding

Forward Error Coding • FEC control errors in data transmission, extend the range and

Forward Error Coding • FEC control errors in data transmission, extend the range and reduces the power requirements for communication system. • Adding Redundancy. • No hand shaking required. • Data travels in one direction only. • Error rate is 2 , where m >= 3. m-1

• FEC is used in high-value communications system, such as cellular telephony, remote

• FEC is used in high-value communications system, such as cellular telephony, remote radio, spread spectrum communications, and satellite transmissions

Types of FEC • There are two types of FEC, namely Block Coding and

Types of FEC • There are two types of FEC, namely Block Coding and Convolutional Coding • Block Coding encoder intersperses parity bits into the data sequence using a particular algebraic algorithm. • Convolutional codes process the incoming bits in streams rather than in blocks. It has powerful error correcting capabilities.

Hamming Encoder • The default code is [7, 4], which encode message of length

Hamming Encoder • The default code is [7, 4], which encode message of length 4 into codewords of length 7

Hamming Decoder • The Hamming decoder block decodes the data after it has been

Hamming Decoder • The Hamming decoder block decodes the data after it has been sent through the channel.

Error Detection Coding • Error detection is the ability to detect errors that are

Error Detection Coding • Error detection is the ability to detect errors that are made due to noise or other impairments in the course of the transmission from transmitter to receiver. • Error detection coding is designed to permit the detection of errors. • A block code converts a fixed length of K data bits to a fixed length N codeword, where N > K.

• A low rate has a high detection probability, but a high redundancy.

• A low rate has a high detection probability, but a high redundancy. • Code Rate = Message length (K) / Codeword length(N) N= 2^M – 1, where M>=3 • A very common code is the single parity check code

To see how the addition of a parity bit can improve error performance, consider

To see how the addition of a parity bit can improve error performance, consider the following example. A common choice of K is eight. Suppose the BER is . Then: So, the probability of a transmission with an error is With the addition of a parity error bit we can detect any single bit error. So: As can be seen, the addition of a parity bit has reduced the uncorrected error rate by three orders of magnitude.

Types of Error detection • CRC Cyclic Redundancy Check Binary CRC’c are very effective

Types of Error detection • CRC Cyclic Redundancy Check Binary CRC’c are very effective for error detection but cannot correct error • LRC Longitudinal Redundancy Check

Forward Error Correcting FEC coding for Super BForward Error Correcting FEC coding for Super B
Dealing with Errors Syntax Errors Runtime Errors ErrorDealing with Errors Syntax Errors Runtime Errors Error
FEC Agape Caring Center 2004 2009 FEC AgapeFEC Agape Caring Center 2004 2009 FEC Agape
FEC Agape Caring Center 2004 2011 FEC AgapeFEC Agape Caring Center 2004 2011 FEC Agape
UTILIZATION OF FORWARD ERROR CORRECTION FEC TECHNIQUES WITHUTILIZATION OF FORWARD ERROR CORRECTION FEC TECHNIQUES WITH
Coding and Error Control Coping with Transmission ErrorsCoding and Error Control Coping with Transmission Errors
Chapter Six Errors Error Detection and Error ControlChapter Six Errors Error Detection and Error Control
Chapter Six Errors Error Detection and Error ControlChapter Six Errors Error Detection and Error Control
Chapter Six Errors Error Detection and Error ControlChapter Six Errors Error Detection and Error Control
Chapter 6 Errors Error Detection and Error ControlChapter 6 Errors Error Detection and Error Control