HARQ Codeword-to-Layer Mapping for Flexible Retransmission Rank
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Solution Overview
Problem
Conventional codeword to layer mappings in multi-antenna systems are not optimal for HARQ operations, particularly during retransmissions, as they limit the ability to reduce the number of simultaneously transmitted codewords without changing the number of layers, leading to inefficiencies and performance losses.
Innovation Solution
Additional codeword to layer mappings are introduced that allow for reducing the number of simultaneously transmitted codewords during retransmissions without altering the number of layers, enabling more flexible transmission rank adjustments based on changing channel conditions, such as mapping a single codeword to two or three layers for different channel ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional codeword to layer mappings are used in multi-antenna systems, then the number of layers remains fixed, but the ability to reduce the number of simultaneously transmitted codewords during retransmissions is limited
Solution Approach 1:
The patent implements dynamic codeword to layer mapping that adapts based on transmission type (initial vs. retransmission) and channel conditions. The mapping mechanism changes its behavior dynamically: for initial transmissions it uses conventional mappings, while for retransmissions it employs alternative mappings that enable reducing the number of simultaneously transmitted codewords by mapping a single codeword to multiple layers (2 or 3 layers), thereby providing flexibility in transmission rank adjustments without requiring changes to the number of layers
Solution Approach 2:
The patent changes the mapping parameters (codeword to layer assignment) based on transmission conditions. By introducing alternative mapping configurations where a single codeword can be mapped to 2 or 3 layers instead of the conventional 1-to-1 mapping, the system can adjust the effective transmission rank during retransmissions without altering the physical layer structure or number of antenna ports
2Productivity
If the number of simultaneously transmitted codewords is reduced during retransmissions, then HARQ efficiency improves, but conventional mappings require changing the number of layers which is not practical
Solution Approach 1:
The patent segments the mapping configuration into different types: conventional mappings for initial transmissions and alternative mappings for retransmissions. This segmentation allows the system to apply appropriate mapping strategies for different transmission scenarios, enabling reduced codeword transmission during retransmissions by using alternative mappings where a single codeword is distributed across multiple layers, thereby improving HARQ efficiency without requiring physical changes to the layer structure
3Adaptability or versatility
If alternative codeword to layer mappings are introduced, then flexible transmission rank adjustments are enabled, but the mapping mechanism becomes more complex
Solution Approach 1:
The system dynamically selects between conventional and alternative mappings based on transmission type indicators. For initial transmissions, conventional mappings are used; for retransmissions, alternative mappings are activated. This dynamic selection mechanism provides transmission rank flexibility (ability to map single codeword to multiple layers) while managing operational complexity through automated selection based on transmission context
Data Source
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AI summary
In a transmitter or transceiver, codewords from HARQ processes can be mapped or assigned to various layers for transmission and/or retransmission of information on a radio channel. Exemplary embodiments provide for various mappings which facilitate, for example, HARQ processes. For example, a codeword can be mapped onto a plurality of layers which are equal in number to a channel rank of a radio channel to be used for the transmission.