Mumbai University > Electronics and Telecommunication Engineering > Sem 6 > Data Communication

Marks: 10 Marks

Year: Dec 2016

Codeword;-

It is the binary bit pattern which consist of k messages bit which represents information symbol and q checkbits which are added by channel coding technique.There are two types.

Systematic:-message bit is clearly distinguish from check bit.

Nonsystematic:-message bit is not clearly distinguish from check bit.

Code word: -

The code word is code consisting of data unit and party bits/redundant bits.

Systematic Codes

For a systematic block code the dataword appears unaltered in the codeword – usually at the start The generator matrix has the structure,

$G=\begin{bmatrix}1&0&..&0&p_{11}&p_{12}&..&p_{1R} \\ 0&1&..&0&p_{21}&p_{22}&..&p_{2R} \\ ..&..&..&..&..&..&..&.. \\ 0&0&..&1&p_{k1}&p_{k2}&..&p_{kr}\end{bmatrix}=[I|P]$

P is often referred to as parity bits

I is k*k identity matrix. Ensures dataword appears as beginning of codeword

P is k*R matrix.