MIMO Precoding With Bit-Length Adjustment for LDPC Mapping
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Solution Overview
Problem
Implementing the MIMO scheme with LDPC coding poses challenges in data processing, particularly in achieving effective data reception quality and transfer rates.
Innovation Solution
The proposed data processing scheme involves a configuration where a transmission device generates and transmits modulated signals using different modulation schemes for each stream, with precoding matrices and phase changes applied to ensure optimal spatial diversity gain and data reception quality, even in environments with dominant direct waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MIMO scheme is implemented with LDPC coding, then data transfer rate is improved, but data reception quality deteriorates in environments with dominant direct waves
Solution Approach 1:
The patent applies different precoding matrices to different spatial streams, optimizing the signal characteristics for each stream independently. This allows the system to maintain high data transfer rates while improving reception quality in specific spatial directions, particularly in environments with dominant direct waves.
Solution Approach 2:
The system dynamically changes precoding parameters including phase shifts and amplitude adjustments in the precoding matrices. By optimizing these parameters, the system achieves both high data transfer rates and improved data reception quality, resolving the contradiction between productivity and reliability.
2Reliability
If different modulation schemes are applied to each stream, then spatial diversity gain is improved, but system complexity increases
Solution Approach 1:
The patent divides the transmission system into separate streams, each with its own modulation scheme and precoding matrix. This segmentation allows independent optimization of each stream for spatial diversity while managing overall system complexity through modular design.
Solution Approach 2:
The precoding matrices are designed to serve multiple functions simultaneously: they provide spatial diversity gain, enable different modulation schemes per stream, and maintain compatibility with LDPC coding. This multi-functionality reduces the need for separate components, thereby managing system complexity.
3Measurement precision
If precoding matrices with phase changes are used, then minimum Euclidean distance is optimized, but processing complexity increases
Solution Approach 1:
The precoding matrices with optimized phase changes are pre-calculated and stored, allowing the system to achieve optimized minimum Euclidean distances without real-time complex processing. This preliminary preparation reduces processing complexity while maintaining measurement precision.
Data Source
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AI summary
An encoder outputs a first bit sequence having N bits. A mapper generates a first complex signal s 1 and a second complex signal s2 with use of bit sequence having X+Y bits included in an input second bit sequence, where X indicates the number of bits used to generate the first complex signal s1, and Y indicates the number of bits used to generate the second complex signal s2. A bit length adjuster is provided after the encoder, and performs bit length adjustment on the first bit sequence such that the second bit sequence has a bit length that is a multiple of X+Y, and outputs the first bit sequence after the bit length adjustment as the second bit sequence. As a result, a problem between a codeword length of a block code and the number of bits necessary to perform mapping by a set of modulation schemes is solved.