MIMO Precoding for Mixed-Modulation Spatial Diversity
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Solution Overview
Problem
Current MIMO communication systems face challenges in optimizing data transmission quality and diversity gain due to differences in modulation schemes and power levels between multiple antennas, leading to suboptimal data reception quality and spatial diversity.
Innovation Solution
The proposed method involves using a precoding matrix that adjusts the modulation schemes and power levels between two antennas, ensuring that the number of signal points in the I-Q plane for each symbol aligns with the bit data, and maintaining specific power ratios to enhance spatial diversity and data reception quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different modulation schemes are used for multiple antennas to adapt to varying channel conditions, then adaptability is improved, but manufacturing precision deteriorates due to difficulty in aligning signal points with bit data
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting modulation schemes (e.g., switching between QPSK, 16QAM, 64QAM) for different antennas based on channel conditions. The key innovation is maintaining precise signal point alignment by coordinating the parameters of different modulation schemes through a precoding matrix, ensuring that signal points from multiple antennas align with their corresponding bit data despite using different modulation orders.
2Productivity
If power levels are adjusted between antennas to optimize transmission, then productivity is improved, but manufacturing precision deteriorates due to difficulty in maintaining signal point distribution
Solution Approach 1:
The patent adjusts power levels between antennas as a parameter change to optimize data transmission rate. Different antennas can transmit with different power levels according to channel conditions, while the precoding matrix ensures that the combined signal maintains proper signal point distribution and alignment, resolving the contradiction between productivity improvement and precision maintenance.
3Reliability
If spatial diversity is enhanced through multiple antennas with different modulation schemes, then reliability is improved, but device complexity increases due to precoding matrix requirements
Solution Approach 1:
The patent introduces a precoding matrix as an intermediary component that processes signals from multiple antennas with different modulation schemes. This intermediary performs coordinate transformations and signal combinations, enabling spatial diversity and improved reception quality while managing the complexity through structured mathematical operations rather than ad-hoc processing.
4Adaptability or versatility
If modulation schemes are optimized for each antenna independently, then adaptability is improved, but loss of information increases due to misalignment between signal points and bit data
Solution Approach 1:
The patent coordinates parameter changes across multiple antennas by using a precoding matrix that ensures signal points from different modulation schemes align with their corresponding bit data. This coordinated approach maintains data reception accuracy while allowing each antenna to adapt its modulation scheme to local channel conditions, preventing information loss that would occur with independent optimization.
Data Source
AI summary
In a transmission method according to one aspect of the present disclosure, a encoder performs error correction coding on an information bit string to generate a code word. A mapper modulates a first bit string in which the number of bits is the predetermined integral multiple of (X+Y) in the code word using a first scheme, the first scheme being a set of a modulation scheme in which an X-bit bit string is mapped to generate a first complex signal and a modulation scheme in which a Y-bit bit string is mapped to generate a second complex signal, and modulates a second bit string in which the first bit string is removed from the code word using a second scheme different from the first scheme.