Uplink Precoding Codebook Selection Under Transmit Power Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE-A, existing codebook structures for precoding in the uplink data transmission lead to performance loss and inefficient power amplification, especially at high signal-to-noise ratios and when transmit power is restricted.
Innovation Solution
A method and codebook structure that dynamically selects codewords from a first codebook with imbalanced power between layers and a second codebook with balanced power between layers based on the total uplink power, and allocates sub-carrier resources to preserve cubic metric characteristics, thereby reducing antenna performance loss and optimizing power amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing codebook structure is used for precoding, then precoding capability is provided, but transmit antenna performance is lost at high signal-to-noise ratio
Solution Approach 1:
The codebook is segmented into multiple codebooks (first codebook with imbalanced power, second codebook with balanced power) to address different transmission scenarios. This segmentation allows selection of the appropriate codebook based on power conditions, thereby preserving transmit antenna performance at high signal-to-noise ratio while avoiding performance loss in other conditions.
Solution Approach 2:
The system dynamically selects between different codebooks based on the total uplink power relative to the rated total transmit power. When power is sufficient (greater than 3/4 of rated power), the first codebook is used; when power is limited (less than or equal to 3/4 of rated power), the second codebook is used. This dynamic adaptation preserves antenna performance across varying operating conditions.
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 invention changes the codebook parameter (selecting between first and second codebooks) based on the power ratio condition. When total uplink power is less than or equal to 3/4 of rated total transmit power, the second codebook with balanced power distribution is selected, which optimizes power amplification utilization and enables full power transfer despite restricted transmit power conditions.
3Adaptability or versatility
If conventional codebook is used, then precoding is enabled, but cubic metric characteristics are not preserved
Solution Approach 1:
The codebook is divided into multiple specialized codebooks, including a third codebook specifically designed to preserve cubic metric characteristics. This segmentation allows the system to maintain precoding capability while preserving cubic metric characteristics by selecting the appropriate codebook based on transmission conditions.
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. Thus, a loss of an antenna performance at a high signal-to-noise ratio is reduced, and the loss of the power amplification of the antenna is reduced if the transmit power of the antenna is restricted.