5G/NR

LDPC

LDPC stands for "Low-Density Parity-Check". It's a method used in communication systems for encoding and decoding data to detect and correct errors. LDPC codes are a type of linear error-correcting code that has found extensive application in modern communication technologies. LDPC codes are a powerful and efficient method for error correction in digital communication systems, enabling reliable data transmission even in challenging and noisy environments.

Here are some key points about LDPC:

  • Error Correction: LDPC codes are particularly effective for correcting data transmission errors in noisy communication channels. They are used in scenarios where accurate data transmission is critical, such as in satellite communication, wireless networks, and data storage.
  • Sparse Parity-Check Matrix: The 'low-density' in LDPC refers to the parity-check matrix used in these codes, which has a relatively small number of non-zero elements. This sparsity is what makes LDPC codes computationally efficient for error correction.
  • Decoding Algorithm: LDPC codes are usually decoded using iterative probabilistic decoding algorithms, such as the belief propagation (BP) algorithm. These algorithms are efficient and can handle a large number of errors.
  • Applications: LDPC codes are widely used in modern communication standards, including Wi-Fi (as part of the IEEE 802.11 standard), 5G cellular networks, and digital television (DVB-T2 and DVB-S2).
  • History and Development: LDPC codes were first introduced by Robert G. Gallager in his doctoral dissertation at MIT in 1960. However, they were not widely used until the 1990s when advancements in digital technology made their implementation more feasible.
  • Performance: LDPC codes are known for their near-Shannon-limit performance. The Shannon limit is a theoretical maximum efficiency for data communication in a channel with a given level of noise.

 

Reference

 

[1] 3GPP TSG RAN WG1 #86 - R1-166414 Discussion on LDPC codes for NR

[2] 3GPP TSG RAN WG1 #86  R1-166769  Discussion on Length-Compatible Quasi-Cyclic LDPC Codes   

[3] 3GPP TSG RAN WG1 #86  R1-166770  Discussion on Rate-Compatible Quasi-Cyclic LDPC Codes

[4] 3GPP TSG RAN WG1 #86 R1-166929  LDPC Code Design for NR

[5] 3GPP TSG-RAN WG1 #86 R1-167532 Discussion on LDPC coding scheme of code structure, granularity and HARQ-IR

[6] 3GPP TSG RAN WG1 #86 R1-167889 Design of Flexible LDPC Codes