MIMO Precoding Segmentation for Interference Reduction
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Solution Overview
Problem
In MIMO wireless communication systems, increasing the number of antennas leads to a decrease in information transmission capacity due to inter-layer interference, making it difficult to achieve proportional communication capacity expansion without orthogonal precoding, which is challenging to implement effectively.
Innovation Solution
The implementation of multi-phase precoding using a combination of internal and external precoding matrices, where the internal precoder uses a matrix satisfying PinPinH=I, and the external precoder uses codewords from codebooks that minimize the difference with eigen vectors of the channel, to reduce inter-layer interference and maintain identical transmission power for each antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of antennas is increased to increase communication capacity, then the theoretical capacity increases, but inter-layer interference increases causing actual capacity to decrease
Solution Approach 1:
The precoding process is segmented into two independent phases: first precoding (performed by external precoder) and second precoding (performed by internal precoder). This segmentation allows each stage to address specific aspects of interference management separately, with the first stage handling spatial multiplexing and the second stage eliminating inter-layer interference through orthogonal design.
Solution Approach 2:
The internal precoder acts as an intermediary component between the layer mapper and the antenna elements. It processes the already precoded symbols from the external precoder and applies additional orthogonal precoding to eliminate inter-layer interference before signal transmission, thus mediating the conflict between capacity and interference.
2Object-generated harmful factors
If orthogonal precoding is used to prevent inter-layer interference, then communication capacity is maintained, but system complexity increases making it difficult to implement
Solution Approach 1:
The complex orthogonal precoding task is segmented into two manageable stages. The external precoder handles spatial multiplexing using standard codebooks, while the internal precoder handles orthogonalization using simplified structures (identity matrix or DFT matrices), reducing the overall implementation complexity compared to a single-stage complex orthogonal precoder.
Solution Approach 2:
The internal precoder uses parameter-based design where the precoding matrix is selected from a limited set of predefined matrices (identity matrix or DFT matrices with different parameters). This parameterization approach simplifies implementation by reducing the design space and enabling efficient selection based on channel conditions without requiring complex real-time optimization.
3Ease of operation
If codebook-based precoding is performed with elements of equal size, then transmission power is uniform across antennas, but the difference between codebook vectors and SVD vectors increases reducing precoding effectiveness
Solution Approach 1:
The precoding function is segmented between external and internal precoders. The external precoder selects codebook vectors that may have elements of equal size for power uniformity, while the internal precoder compensates for the precision loss by applying orthogonal precoding that aligns the effective transmitted signal more accurately with the channel eigenvectors, thus maintaining both power uniformity and precoding effectiveness.
Data Source
AI summary
An embodiment of the present invention relates to a wireless communication system, wherein said wireless communication system uses multiple input and multiple output antenna (MIMO) on both transmission and receiving ends.