R1-2600189
discussion
Discussion on 6G channel coding
From OPPO
Summary
This OPPO document presents 2 Observations and 2 main Proposals for 6G channel coding. It covers LDPC enhancements for data throughput via larger lifting sizes and new protographs, and Polar coding extensions to support DCI payload sizes exceeding the 5G limit of 140 bits through interleaver modifications.
Position
OPPO proposes increasing LDPC lifting size up to 2*Z for BG1 or 4*Z for BG2 as a simple method to double data channel throughput while maintaining or improving decoding performance over 5G. They present technical case for a new LDPC protograph achieving about 0.2 dB gain over 5G BG1 at 5 iterations with better performance-complexity tradeoff for high code rates. They propose studying solutions to increase Polar code DCI payload size beyond the 5G limit of 140+24 bits, specifically by re-defining the interleaver table to cover all bits (Scheme 1) or by only applying legacy interleaving over the last 140+24 bits (Scheme 2). OPPO argues the upper-bound restriction of 140 information bits already became a potential bottleneck in Rel-17 DSS and Rel-18 multi-carrier enhancement.
Key proposals
- Observation 1 (Sec 1.1.1): Increasing lifting size (up to 2*Z for BG1 or 4*Z for BG2) is a simple and solid way to double LDPC throughput and meanwhile to consistently maintain or even improve decoding performance over 5G.
- Observation 2 (Sec 1.1.2): There exists new LDPC code protograph exhibiting better performance at large iterations at cost of slightly higher complexity, about 0.2 dB gain over 5G BG1 at iteration 5, and better performance-complexity tradeoff than 5G BG1 for high code rate.
- Observation 3 (Sec 1.2): By following the RAN1 analysis assumptions for Rel-17 DSS and Rel-18 MC-enhancement, the total number of DCI information bits has a good chance to exceed 140 or even 200.
- Proposal 1 (Sec 1.2): Study solutions to increase DCI payload size in 6G, where the principle of the solution should hold against the uncertainty of the exact DCI payload size upper-bound.
- Proposal 2 (Sec 1.2): Study the following schemes of interleaving to enable the maximum DCI payload size to be larger than the one (140+24) in 5G. Scheme 1: Follow the legacy design principle to re-define the interleave table (i.e., defined in TS38.212) to support a maximum Polar code payload size that is larger than (140+24). Scheme 2: Only apply the legacy interleaving over the last (140+24) bits.