BLOCK CODING

We need redundancy to ensure synchronization and to provide some kind of inherent error detecting. Block coding can give us this redundancy and improve the performance of line coding. block coding changes a block of m bits into a block of n bits, where n is larger than m. Block coding is referred to as an mB/nB encoding technique.

Block coding normally involves three steps: division, substitution,

1. and combination.
2. In the division step, a sequence of bits is divided into groups of m bits.
3. In the substitution step, we substitute an m-bit group for an n-bit group.
4. Finally, the n-bit groups are combined together to form a stream.

Note

Block coding is normally referred to as

mB/nB coding;

it replaces each m-bit group with an

n-bit group.

Block coding concept

Using block coding 4B/5B with NRZ-I line coding scheme

4B/5B mapping codes

Substitution in 4B/5B block coding

8B/10B block encoding