8B/10B Encoding: Advantages and Disadvantages

This page explores the advantages and disadvantages of 8B/10B block coding, detailing its benefits and drawbacks.

What is 8B/10B Encoding?

Introduction: 8B/10B is a block coding technique that, similar to 4B/5B encoding, uses redundancy to ensure synchronization and improve performance. It also offers inherent error detection capabilities. The name “8B/10B” signifies that the encoding process takes 8-bit blocks as input and produces 10-bit blocks as output.

The 8B/10B block coding scheme is a combination of 5B/6B and 3B/4B encoding, as illustrated below:

The most significant bits (MSBs) of the 8-bit block are fed into a 5B/6B encoder, while the 3 least significant bits (LSBs) are fed into a 3B/4B encoder module. The coding has 2¹⁰ - 2⁸ redundant groups.

Benefits or Advantages of 8B/10B Encoding

The following are the benefits or advantages of 8B/10B encoding:

• Disparity Control: It employs a disparity controller to keep track of excess 0s over 1s (or vice versa). This helps to prevent long runs of consecutive 0s or 1s, which can cause synchronization issues.
• Error Detection: The redundant groups can be used for disparity checking and error detection, improving the reliability of the transmitted data.
• Superior to 4B/5B: It offers better performance than 4B/5B coding due to its built-in error checking capability and improved synchronization.

Drawbacks or Disadvantages of 8B/10B Encoding

The following are the drawbacks or disadvantages of 8B/10B encoding:

• Overhead: The redundant data introduces overhead, increasing the overall bandwidth requirements.