Multi-Stage DCI Polar Coding with Split CRC Decoding
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Solution Overview
Problem
Existing polar codes are not designed to support multi-stage Downlink Control Information (DCI) transmission effectively, which is necessary for New Radio (NR) wireless communication systems, as they are primarily optimized for single-stage DCI transmission.
Innovation Solution
The proposed solution involves transmitting a first part of multi-stage DCI in a first Orthogonal Frequency Division Multiplexing (OFDM) symbol and a second part in a subsequent OFDM symbol, with Cyclic Redundancy Check (CRC) bits attached to either or both parts, and using polar encoders to encode the DCI parts, where the first part can be used as frozen bits for encoding the second part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing polar codes are used for single-stage DCI transmission, then the coding scheme is simple and well-optimized, but it cannot support multi-stage DCI transmission required for New Radio systems
Solution Approach 1:
The DCI message is divided into two separate parts: DCI_part1 transmitted in an earlier OFDM symbol and DCI_part2 transmitted in a later OFDM symbol. Each part is independently encoded and can be decoded separately, enabling multi-stage transmission while maintaining compatibility with existing polar code structures.
Solution Approach 2:
DCI_part1 is transmitted and decoded before DCI_part2 arrives. The UE can perform preliminary decoding of DCI_part1 to obtain resource allocation information, which is then used to properly decode and interpret DCI_part2 containing MCS and HARQ information.
2Productivity
If DCI is transmitted in two separate stages, then the processing timeline is improved and independent decoding is enabled, but error detection and control becomes more complex
Solution Approach 1:
The error detection mechanism is segmented to match the two-part DCI structure. Each part (DCI_part1 and DCI_part2) has its own CRC bits attached independently, allowing separate error detection for each transmitted part while maintaining overall reliability.
Solution Approach 2:
CRC bits are attached to both DCI parts to provide feedback mechanisms for error detection. The independent CRC checks enable the receiver to verify each part separately and request retransmission only for erroneous parts, improving overall system reliability.
3Reliability
If CRC bits are attached to both DCI parts, then error detection capability is enhanced, but the overhead increases
Solution Approach 1:
The CRC overhead is segmented and distributed across the two DCI parts rather than having a single large CRC for the entire message. This allows each part to have appropriate error detection coverage while minimizing total overhead compared to protecting the entire DCI message with one large CRC.
Data Source
AI summary
Systems and methods for multi-stage downlink control information transmission in a manner that supports existing polar codes are provided. In some embodiments, a method of operation of a radio access node in a cellular communications network to transmit multi-stage downlink control information comprises transmitting a first part of a multi-stage downlink control information in a first Orthogonal Frequency Division Multiplexing (OFDM) symbol and transmitting a second part of the multi-stage downlink control information in a second OFDM symbol that is subsequent to the first OFDM symbol. Cyclic Redundancy Check (CRC) bits are attached to the first part of the multi-stage downlink control information and/or CRC bits are attached to the second part of the multi-stage downlink control information. In some embodiments, the first part and/or the second part of the multi-stage downlink control information is encoded using a polar encoder.