Uplink MIMO Retransmission Power Scaling
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Solution Overview
Problem
Current technologies face challenges in selecting appropriate precoding for retransmissions in uplink MIMO Hybrid ARQ systems, especially when the number of codewords or transmission rank in retransmissions is less than in original transmissions, and there is a need for efficient power scaling and resource allocation in non-adaptive hybrid ARQ for uplink MIMO.
Innovation Solution
A method for obtaining a precoder for retransmission based on known precoding matrices and modulation and coding schemes, and scaling power using parameters such as index of UL precoder, rank, MCS assignments, and channel information to ensure efficient power usage and resource allocation, where the retransmission power is scaled by a factor θ=βr′/r, and β is determined by various information parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-adaptive HARQ retransmission is used with fixed resource block and MCS, then scheduling simplicity is improved, but power efficiency deteriorates when transmission rank or number of codewords changes
Solution Approach 1:
The patent introduces dynamic power scaling factors that adapt to changes in transmission rank and number of codewords. The power scaling factor θ is calculated based on the ratio of current to previous transmission parameters, enabling the system to maintain power efficiency while operating within the non-adaptive HARQ framework. This dynamic adjustment resolves the contradiction by adding flexibility only where needed (power control) while preserving the overall simplicity of non-adaptive scheduling.
Solution Approach 2:
The patent changes the power parameter dynamically based on transmission conditions. By introducing power scaling factors that depend on transmission rank and codeword count, the system adjusts power allocation without changing the fundamental non-adaptive HARQ structure. This allows power efficiency to be improved while maintaining scheduling simplicity through parameter-based adaptation rather than structural complexity.
2Device complexity
If the same precoding matrix is used for retransmission as in original transmission, then implementation complexity is reduced, but transmission reliability deteriorates when channel conditions change
Solution Approach 1:
The patent selects precoding matrices from a predefined codebook in advance, organizing them by rank. This preliminary organization allows the UE to quickly select an appropriate precoder for retransmission based on current conditions without complex real-time optimization. The system prepares multiple precoding options beforehand, enabling reliable adaptation to channel changes while keeping implementation simple through codebook-based selection rather than complex matrix design.
Solution Approach 2:
The patent enables dynamic precoder selection from the codebook based on current transmission rank and channel conditions. The UE can switch between different precoding matrices in the codebook depending on whether the retransmission uses the same or different rank/codewords. This dynamic selection improves reliability by adapting to channel changes while maintaining simplicity through the use of predefined codebook structures rather than complex adaptive algorithms.
3Device complexity
If power is not scaled for retransmission, then power management is simplified, but resource allocation efficiency deteriorates when transmission parameters change
Solution Approach 1:
The patent implements self-service power scaling at the UE side through autonomous calculation of power scaling factors. The UE independently determines the appropriate power scaling based on transmission rank and codeword count changes without requiring complex base station control. This self-service approach maintains simple power management from the network side while achieving efficient resource allocation through UE-side adaptation, resolving the contradiction by distributing intelligence to where it is most needed.
Solution Approach 2:
The patent introduces power scaling parameters that automatically adjust based on transmission conditions. The power scaling factor θ is derived from measurable parameters like transmission rank and codeword count, enabling efficient resource allocation through parameter-based control rather than complex power management algorithms. This allows the system to maintain simple power management procedures while achieving high resource allocation efficiency through intelligent parameter adjustment.
Data Source
AI summary
A method includes obtaining a precoder for retransmission of one codeword responsive to known precoding matrix P of rank r and modulation and coding scheme MCS assignments used in an original transmission, and a desired retransmission rank r′; and scaling power in the retransmission responsive to at least two of 1) information parameters Index of UL precoder in previous transmission, 2) rank r of uplink UL precoder in previous transmission, 3) MCS assignments in previous retransmission (MCSi), 4) rank r′ for UL retransmission 5) number of retransmit antennas used for codeword to be retransmitted x in previous transmission, 6) number of retransmit antennas x′ used for retransmission, 7) precoder for UL retransmission, 8) UL precoders and channel information for previous transmission, and 8) latest channel measurements.