High and low code rates in channel encoding

Dear,

I want to know if in the field of channel encoding (error correction codes), the performances are good when the code rate is low or higher ?

For example if we have code rates (1/6, 1/3, 2/3, 4/5, 7/8 ....), which code rate is more performant?

And how can we explain that !

Answer 1

[Amish]

Hi Afluo,

In the field of channel encoding and error correction codes, performance is generally measured in terms of error correction capability and bit error rate (BER) performance under different signal-to-noise ratio (SNR) conditions. The following can be the impacts of Code Rate on the performance:

a. Lower code rate (e.g., 1/6, 1/3)

• More redundancy is added to the transmitted data.
• Higher error correction capability.
• Better performance in noisy environments (low SNR).
• More robust communication but lower spectral efficiency.

b. Higher code rate (e.g., 2/3, 4/5, 7/8)

• Less redundancy, meaning fewer extra bits for error correction.
• Lower error correction capability.
• Requires a higher SNR for reliable transmission.
• More efficient use of bandwidth.

Therefore, the answer depends on the performance metric being used. If performance is defined as error correction capability, lower code rates (e.g., 1/6, 1/3) perform better since they introduce more redundancy and can correct more errors. Whereas, if performance is defined as spectral efficiency (useful data rate), then higher code rates (e.g., 4/5, 7/8) are better because they carry more information bits per transmitted symbol.

This is why in low SNR environments, low code rates are preferred to ensure reliable data reception. In contrast, in high SNR conditions , high code rates are used to maximize throughput.

I hope this clears your query.