PDCCH DCI Format Mapping for Reliable Blind Detection
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Solution Overview
Problem
The nested encoding feature of polar codes in 5G systems leads to indistinguishable DCI formats, causing failures in blind detection, which affects the communication capability of terminal devices.
Innovation Solution
The method involves generating and processing downlink control information (DCI) by scrambling and reordering the radio network temporary identifier (RNTI) and cyclic redundancy check (CRC) codes based on specific formats, allowing terminal devices to determine the correct DCI format through a mapping relationship and corresponding processing manners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polar code nested encoding is used for DCI formats, then encoding efficiency is improved, but DCI format distinguishability deteriorates causing blind detection failures
Solution Approach 1:
The patent applies preliminary action by performing bit reordering on DCI payloads before encoding. Specifically, bits at different positions are swapped according to predetermined rules that depend on the DCI format type. This preliminary reordering ensures that even with nested encoding, the final encoded sequences for different formats remain distinguishable, allowing successful blind detection while maintaining encoding efficiency
Solution Approach 2:
The patent applies local quality by making the bit reordering operation format-dependent. Different DCI formats undergo different reordering patterns, creating local distinctions in the encoding process. This allows the system to maintain high encoding efficiency through polar code nested structure while introducing format-specific variations that enable reliable format identification during blind detection
2Reliability
If blind detection is performed on multiple potential PDCCH locations, then DCI reception reliability is improved, but false alarm rate increases
Solution Approach 1:
The patent reduces false alarm rates by performing preliminary bit reordering based on expected DCI formats before blind detection. This allows the terminal to narrow down the search space and perform fewer blind detection attempts, thereby maintaining reliable DCI reception while reducing the cumulative false alarm probability that increases with each additional detection attempt
3Adaptability or versatility
If multiple DCI formats are supported for the same UE state, then communication versatility is improved, but format identification difficulty increases
Solution Approach 1:
The patent applies preliminary bit reordering operations that are specific to each DCI format before encoding. This creates distinct patterns in the encoded sequences for different formats, allowing the terminal to identify the correct format through blind detection without increasing complexity. The reordering is performed automatically as part of the encoding process, maintaining versatility while avoiding manual configuration complexity
Solution Approach 2:
The bit reordering operation serves as an intermediary mechanism between the DCI payload and the polar code encoding process. This intermediary step introduces format-specific transformations that enable differentiation without requiring changes to the underlying polar code structure or adding complex identification overhead, thus supporting multiple formats while controlling device complexity
Data Source
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AI summary
This application provides an information transmission method, a network device, and a terminal device. The method includes: generating, by a network device, downlink control information DCI; determining, by the network device, a corresponding processing manner based on a format of the DCI; performing, by the network device, processing in the processing manner in an encoding process of the DCI; and sending, by the network device, the processed DCI over a physical downlink control channel PDCCH. The information transmission method provided in this application can resolve a problem of a failure in blind detection on DCI caused by a nested encoding feature of polar encoding. When a terminal device cannot determine the format of the DCI sent by the network device, the network device may use a mapping relationship, and the network device processes DCI of a format in a processing manner. After a processing manner of the terminal device corresponds to the processing manner of the network device, a type of the DCI can be determined, and content of the DCI can be parsed.