Precoding Codebook Selection for Uplink Power Optimization
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Solution Overview
Problem
In LTE-A systems, existing codebook structures for precoding lead to performance loss in transmit antennas at high signal-to-noise ratios and restrict power amplification when transmit power is limited, failing to preserve cubic metric characteristics and resulting in high complexity and imbalanced power distribution.
Innovation Solution
A method and codebook structure that dynamically select codewords from imbalanced and balanced power codebooks based on uplink power and sub-carrier resource allocation, ensuring reduced antenna performance loss and balanced power amplification, while preserving cubic metric characteristics through CMP and CMF codebooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing codebook structure is used for precoding, then precoding capability is provided, but transmit performance is lost at high signal-to-noise ratio
Solution Approach 1:
The patent implements dynamic codebook selection based on signal-to-noise ratio conditions. The base station determines whether to use codebook type I or type II based on the reported CSI and SNR thresholds, allowing the system to adaptively switch between balanced and imbalanced power distribution strategies to optimize transmit performance under different channel conditions.
Solution Approach 2:
The patent changes the power distribution parameters of the codebook based on operating conditions. Codebook type I uses imbalanced power distribution (e.g., 3:1 ratio) for high SNR conditions to maximize antenna performance, while codebook type II uses balanced power distribution for low SNR conditions to ensure reliable transmission, thereby resolving the performance loss issue.
2Power
If transmit power is restricted, then power control is achieved, but power amplification cannot be fully utilized for full power transfer
Solution Approach 1:
The patent modifies the power distribution parameters across antenna ports based on total power constraints. When power is restricted, the system selects codebook type I with imbalanced distribution to ensure that at least one antenna operates at full power, maximizing power amplifier utilization while respecting the overall power limit.
Solution Approach 2:
The system dynamically adjusts the power distribution pattern across antennas based on the ratio of available power to rated power. This allows the base station to optimize the use of power amplifiers by concentrating power on specific antennas when total power is limited, thereby improving productivity without violating power constraints.
3Reliability
If codebook structure is optimized for performance, then transmit performance improves, but complexity increases
Solution Approach 1:
The patent segments the codebook into two distinct types (type I and type II) with different power distribution characteristics. This segmentation allows the system to select the appropriate codebook based on operating conditions, achieving high performance without requiring a single overly complex codebook structure. The segmentation reduces complexity by dividing the solution space into manageable, condition-specific subsets.
Solution Approach 2:
The patent implements dynamic selection between simplified (type I) and enhanced (type II) codebook structures based on channel conditions. This dynamic approach allows the system to use the simpler codebook when conditions permit, reducing computational complexity, while switching to the more complex codebook only when performance benefits justify the additional complexity.
4Productivity
If imbalanced power distribution is used, then power amplification utilization improves, but antenna performance loss increases at high SNR
Solution Approach 1:
The patent dynamically switches between imbalanced (codebook type I) and balanced (codebook type II) power distribution based on signal-to-noise ratio conditions. At high SNR, the system uses imbalanced distribution to maximize power amplifier utilization, while at low SNR, it switches to balanced distribution to maintain antenna performance, thereby resolving the contradiction through conditional adaptation.
Solution Approach 2:
The patent changes the power distribution parameters of the codebook based on operating conditions. By adjusting the power ratio parameters between antennas according to SNR thresholds, the system optimizes both power amplification utilization and antenna performance, avoiding the performance loss that would occur with fixed imbalanced distribution.
Data Source
AI summary
A method, a codebook, and a Base Station (BS) for precoding are provided. The precoding method includes: obtaining a total uplink power of a User Equipment (UE); if the total uplink power is greater than ¾ of a rated total transmit power of antennas, selecting a codeword from a first codebook with imbalanced power between layers; otherwise, selecting a codeword from the first codebook and a second codebook with balanced power between layers, so as for precoding data to be transmitted according to the selected codeword.