Rank-3 Precoding Matrices for SC-FDMA MIMO Power Balancing
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Solution Overview
Problem
The existing SC-FDMA MIMO systems face challenges with increased Peak-to-Average Power Ratio (PAPR) at individual antennas due to precoding matrix mixing, which limits transmission power and degrades system performance, especially in the high Signal to Noise Ratio (SNR) region.
Innovation Solution
The use of rank-3 precoding matrices that map multiple codewords to different antennas while maintaining equal power ratios between layers, preventing PAPR increases and ensuring balanced power allocation across antennas, thereby enhancing system performance across the entire SNR range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If precoding matrix mixing is applied to SC-FDMA MIMO, then data transmission efficiency is improved, but PAPR increases at individual antennas
Solution Approach 1:
The patent segments the codebook into multiple subsets, where each subset contains precoding matrices with specific properties (equal power ratios between layers). By selecting matrices from these segmented subsets, the system maintains layer power equality while achieving spatial diversity, thus improving data transmission efficiency without causing PAPR increase
Solution Approach 2:
The patent changes the parameter selection criteria for precoding matrices by imposing constraints on power ratios between layers. This parameter change ensures that selected matrices maintain equal power distribution across layers, preventing PAPR increase while still enabling efficient MIMO transmission
2Reliability
If rank-3 precoding matrices are used to map multiple codewords to different antennas, then transmit diversity effects are enhanced, but system performance degrades in high SNR region
Solution Approach 1:
The patent implements dynamic codebook subset selection based on channel conditions. The base station evaluates the channel state and dynamically selects the most appropriate codebook subset and precoding matrix, allowing the system to adapt to varying SNR conditions and optimize performance across different operating scenarios
3Reliability
If power amplifier back-off is increased to prevent non-linear distortion, then signal linearity is maintained, but maximum transmission power is reduced
Solution Approach 1:
The patent converts the potential harm of PAPR increase into a benefit by carefully designing codebook subsets that maintain equal power ratios. This approach allows the system to operate closer to the power amplifier's maximum capacity without causing non-linear distortion, effectively converting the power constraint into an opportunity for optimized power utilization
Data Source
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AI summary
A method and apparatus for transmitting and receiving signals using a codebook which maps each codeword to at least two different antennas is provided for a MIMO system. A transmission method includes mapping multiple codewords to multiple layers; mapping the multiple layers to multiple antennas using a precoding matrix selected from a rank-3 codebook which is designed to map the codewords to different antennas; and transmitting the codewords through paths formed by mapping the layers and the antennas. The precoding matrix of the rank-3 codebook is designed to equalize transmit power ratios between the antennas. The communication method and apparatus is advantageous to solve the problem of transmit power imbalance among the layers and the problem of performance degradation at the high SNR region in the conventional system using the rank-3 precoding matrices.