MIMO Layer Mapping for Codeword Retransmission
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Solution Overview
Problem
In MIMO-based data retransmission, the issue arises when the number of layers selected by the transmitter exceeds the number required for retransmitting a codeword, leading to difficulties in normal operation between the transmitter and receiver, especially when no new data needs to be transmitted.
Innovation Solution
The method involves determining a special codeword based on the difference between the selected layers and the required layers for retransmission, using a virtual or filling codeword, and allocating these through layer mapping to ensure consistent layer usage, with a special codeword transmission indication sent to the receiver to facilitate normal retransmission processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmitter uses a fixed number of layers for retransmission, then the retransmission process is simple, but the system cannot adapt when the selected layers exceed the required layers
Solution Approach 1:
The patent makes the number of layers dynamic by allowing the transmitter to adjust the number of layers for retransmission based on the actual number of codewords that need retransmission. Instead of using a fixed layer configuration, the system dynamically determines the layer count to match the retransmission requirements, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The patent changes the parameter of layer count from a fixed value to a variable that adapts to the retransmission needs. By modifying this key parameter based on the number of NACKed codewords and available buffer layers, the system achieves adaptability without excessive complexity.
2Reliability
If the transmitter determines a special codeword structure, then normal retransmission can proceed with layer mismatch, but the codeword structure becomes more complex
Solution Approach 1:
The patent segments the retransmission process into two parts: determining the number of layers needed for actual retransmission, and filling the remaining layers with a special codeword structure. This segmentation allows the system to maintain reliability by ensuring all necessary codewords are retransmitted while using a standardized filling mechanism for the special codeword, thus not significantly increasing overall complexity.
Solution Approach 2:
The special codeword acts as an intermediary element that bridges the gap between the actual retransmission requirements and the selected layer configuration. This intermediary allows the system to proceed with the predetermined layer structure while still accommodating variable retransmission needs, maintaining reliability without requiring complete restructuring of the codeword system.
3Adaptability or versatility
If the transmitter and receiver use different layer counts, then layer flexibility is improved, but synchronization between transmitter and receiver deteriorates
Solution Approach 1:
The patent uses feedback mechanisms where the transmitter determines the special codeword structure based on retransmission requirements, and the receiver, knowing the layer mapping rules, can independently determine the same structure. This feedback-based approach allows different layer counts to be used while maintaining synchronization through shared knowledge of the determination rules.
Solution Approach 2:
The patent creates a universal layer mapping rule that works for both the transmitter's selected layer configuration and the receiver's expected configuration. By establishing a universal determination method that both sides follow, the system achieves flexibility in layer configuration while maintaining synchronization through the universal rule set.
Data Source
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AI summary
The present invention discloses a data retransmission method, apparatus, and system, and relates to the field of communications, so as to solve a problem that it may be difficult for a transmitter and a receiver to work normally in a case that the number of layers selected by the transmitter to use is greater than the number of layers required for retransmitting a codeword and no new data needs to be transmitted. The method includes: in a case that the number of layers that need to be occupied by a codeword to be retransmitted is smaller than the number of layers selected by a transmitter to use and no new data needs to be transmitted, determining a special codeword according to a difference between the number of layers selected by the transmitter and the number of layers that need to be occupied for retransmitting the codeword, where the number of transport blocks included in the special codeword is equal to the difference; and allocating the codeword that needs to be retransmitted and the special codeword to each transport layer through a layer mapping.