Adaptive Two-Stage Downlink Control Channel for 5G
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Solution Overview
Problem
Conventional wireless communication systems face high signaling overhead during code block group retransmissions in 5G and next-generation networks, leading to reduced throughput and capacity due to the use of fixed-length bitmaps for indicating failed code blocks, which does not efficiently adapt to varying numbers of code blocks and resource allocations.
Innovation Solution
An adaptive two-stage downlink control channel structure is implemented, where the first stage maintains a fixed format for scheduling parameters and the second stage uses a variable length bitmap to explicitly indicate code blocks for retransmission, optimizing the length based on the number of code blocks and resource allocation, thereby reducing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed-length bitmap is used to indicate failed code blocks in conventional systems, then the downlink control channel structure is simple and easy to decode, but the signaling overhead increases and throughput decreases when the number of code blocks varies
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed-length bitmap to a variable-length bitmap that adapts to the actual number of code blocks. The bitmap length is dynamically adjusted based on the transport block size and number of code blocks, allowing the system to optimize signaling overhead while maintaining decodeability. This resolves the contradiction by making the control channel structure flexible rather than rigid.
Solution Approach 2:
The patent changes the parameter of bitmap length from a fixed value to a variable value that depends on the number of code blocks and transport block size. By introducing parameter changes, the system can reduce signaling overhead when fewer code blocks are present while maintaining adequate coverage when more code blocks are transmitted, thus resolving the trade-off between overhead and complexity.
2Productivity
If a variable-length bitmap is used to optimize signaling overhead, then the throughput and resource allocation efficiency improve, but the device complexity and decoding complexity increase
Solution Approach 1:
The patent applies preliminary action by providing advance notification to the user equipment about the variable bitmap structure through higher-layer signaling or control information. This allows the receiver to prepare the appropriate decoding configuration before receiving the actual control message, reducing the perceived complexity at the decoding stage while maintaining the throughput benefits of variable-length bitmaps.
3Reliability
If the bitmap length is increased to cover more code blocks, then all code blocks can be indicated, but the signaling overhead increases and resource efficiency decreases
Solution Approach 1:
The patent uses dynamics to adjust the bitmap length according to the actual number of code blocks that need to be indicated. Rather than always using the maximum possible bitmap length, the system dynamically scales the bitmap to match the actual requirements, ensuring complete indication of failed code blocks while minimizing the consumption of downlink control channel resources.
Data Source
AI summary
An adaptive two-stage downlink control channel structure is utilized for control channel transmission with code block group (CBG) retransmission for 5G and other next generation wireless systems. In an aspect, the first stage of the two-stage downlink control channel structure utilizes a defined format (e.g., having a fixed length) and provides information that is employable to determine the length and/or coding scheme of the second stage. In another aspect, the second stage of the two-stage downlink control channel structure utilizes a variable length/size to indicate the CBGs that are scheduled to be retransmitted (e.g., by employing a variable length bitmap). As an example, the length/size is varied based on a length/size of a transport block, from which the CBGs have been generated.