Spatial-Frequency Multiplexing Precoding for MIMO Interference
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Solution Overview
Problem
Current multi-antenna MIMO systems face challenges in reducing residual symbol interference, particularly in large-scale networks, where existing precoding methods require complex matrix operations and are not feasible for a large number of antennas, leading to performance issues.
Innovation Solution
A method involving spatial frequency multiplexing, addition of spatial redundancy symbols, and precoding using a focusing matrix to transmit data symbols, which allows for interference reduction by exploiting channel hardening, enabling simple equalization schemes even with a large number of antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precoding methods are used to reduce residual symbol interference, then transmission performance is improved, but device complexity increases due to complex matrix operations
Solution Approach 1:
The patent segments the precoding process into two distinct parts: a focusing matrix operation that concentrates signal energy on target antennas, and a spreading matrix operation that distributes energy to neighboring antennas. This segmentation allows each matrix to be optimized independently, reducing overall computational complexity while maintaining transmission performance.
Solution Approach 2:
The patent extracts and addresses the source of interference separately by identifying that focal spots centered on target antennas interfere with neighboring antennas. By taking out this interference problem and handling it through the spreading matrix operation, the system achieves interference reduction without requiring complex full-matrix inversions.
2Productivity
If a large number of antennas are used in MIMO systems, then transmission capacity increases, but feasibility of matrix operations decreases
Solution Approach 1:
By segmenting the precoding into focusing and spreading matrices, the patent makes the system scalable to large numbers of antennas. The focusing matrix handles the primary signal direction while the spreading matrix manages interference, allowing independent optimization and reducing computational burden as antenna count increases.
Solution Approach 2:
The patent changes the approach from using a single complex precoding matrix to using two specialized matrices with different functions. This parameter change in the mathematical structure allows the system to handle large-scale MIMO configurations where traditional single-matrix approaches become infeasible.
Data Source
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AI summary
The invention relates to a method for a transmitter device comprising M transmitting antennas to transmit to a receiving device comprising N+C receiving antennas, M, N and C being integers no lower than 1, including: a step (E10) of spatial-frequency multiplexing a block of N data symbols D1, D2,...,DN, resulting in a block of N useful spatial symbols SU1, SU2,...,SU,N, said step using an inverse discrete Fourier transform (IDFT); a step (E20) of adding C redundant spatial symbols to the block of N useful spatial symbols, resulting in a block of N+C spatial symbols S1, S2, SN+C; and a step (E30) of precoding the block of N+C spatial symbols S1 S2, SN+C using a focussing matrix with the dimensions Mx(N+C), thereby providing M precoded spatial symbols X1, X2, XM, each precoded spatial symbol being transmitted via a separate transmission antenna.