Extended DCI Mechanism for HARQ Efficiency in 5G NR
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Solution Overview
Problem
The existing 5G New Radio (5GNR) system faces inefficiencies in Code Block Group (CBG)-based Hybrid Automatic Repeat Request (HARQ) mechanism due to limitations in the number of supported CBGs, difficulty in maintaining the same Transport Block (TB) size during retransmissions, and constraints on Downlink Control Information (DCI) size, which affect HARQ efficiency and decoding accuracy.
Innovation Solution
The implementation of an extended DCI mechanism that includes additional control information in the Physical Downlink Shared Channel (PDSCH), allowing for more than 8 CBGs to be supported within one TB, flexible TB size determination, and increased DCI capacity without altering the existing PDCCH blind detection mechanism, using fields like CBGRI and prbOffset to enhance HARQ efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of CBGs is increased to improve HARQ efficiency, then the DCI size must be increased, but the PDCCH blind detection mechanism cannot support larger DCI sizes
Solution Approach 1:
The patent divides the control information into two parts: the original DCI format transmitted via PDCCH for blind detection, and an extended DCI format transmitted via PDSCH for additional CBG information. This segmentation allows the PDCCH to maintain its size constraints while the PDSCH carries the extended control information needed for supporting more CBGs.
Solution Approach 2:
The patent introduces an intermediary mechanism where the PDSCH acts as a carrier for the extended DCI format. The PDSCH serves as a mediator that delivers additional control information (CBG transmission information, CBG retransmission information) without burdening the PDCCH blind detection mechanism, thus enabling support for more than 8 CBGs.
2Measurement precision
If the TB size is maintained during retransmissions to ensure decoding accuracy, then the MCS must be adjusted, but the discrete quantized RE efficiency levels make it difficult to achieve exact TB size matching
Solution Approach 1:
The patent introduces dynamic adjustment of the TB size determination formula by adding a scaling factor that can be indicated via the extended DCI format in PDSCH. This allows the TB size to be dynamically scaled during retransmissions to match the original TB size exactly, overcoming the limitation of discrete quantized RE efficiency levels in the standard MCS mechanism.
3Quantity of substance
If more control information is added to DCI to support more CBGs, then the DCI capacity increases, but the existing PDCCH blind detection mechanism has size constraints
Solution Approach 1:
The patent moves the extended control information from the traditional PDCCH dimension to the PDSCH dimension. By transmitting the extended DCI format (containing CBG transmission information, CBG retransmission information, etc.) via PDSCH instead of PDCCH, the system充分利用 the resource dimensions available in PDSCH to carry additional control information without interfering with the PDCCH blind detection mechanism.
Data Source
AI summary
A method in a wireless device is provided. The method includes: receiving a downlink signal, wherein the downlink signal includes a Physical Downlink Control Channel (PDCCH) and a Physical downlink Shared Channel (PDSCH), the PDCCH having first downlink Control Information (DCI) indicating at least second downlink control information (DCI) in the PDSCH; and performing one of encoding and decoding user data in the PDSCH based on the first DCI and second DCI. A wireless device implementing this method is provided as well.