R1-2601917
discussion
Considerations on 6GR Channel Coding
From Thales
Summary
This Thales-led contribution proposes studying a concatenated BCH outer code with extended LDPC for 6G to mitigate the error floor in high-reliability scenarios. The document contains 2 Observations in the Introduction, 3 Observations in the main study, and a total of 2 unique Proposals that are recapitulated in the Conclusion.
Position
Thales proposes studying a concatenated BCH outer code to ensure Quasi-Error-Free (QEF) performance, specifically observing that as LDPC code block sizes increase to 16896 bits, the impact of the inherent Error Floor can become more pronounced in high-throughput scenarios or sensitive NTN links. They propose that RAN1 evaluate this BCH+LDPC scheme using a short BCH outer code (t≈8–10) focusing on post-decoding BER/BLER in the error-floor region, impact on HARQ retransmissions and latency for NTN, and implementation complexity overhead relative to pure LDPC. They draw technical justification from the DVB-S2/S2X standards (ETSI EN 302 307) where this two-layer error correction strategy achieves QEF performance critical for broadcast applications, arguing that the BCH code acts as a final clean-up stage for LDPC residual errors.
Key proposals
- Proposal 1 (Sec RAN1#124 agreements / Conclusion): Study a concatenated BCH outer code to ensure Quasi-Error-Free (QEF) performance.
- Proposal 2 (Sec Proposed coding parameters / Conclusion): It is proposed that RAN1 considers evaluating a concatenated BCH+LDPC scheme, where the LDPC (e.g. 16 896 / 44 columns) remains the inner code and a short BCH outer code with (t approx 8–10) is used to remove LDPC residual errors.