MIMO Precoding Bit-Length Alignment for LDPC Codewords
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Solution Overview
Problem
Implementing the MIMO scheme with LDPC coding poses challenges due to bit length mismatches between different coding schemes.
Innovation Solution
A data processing scheme that includes an encoding step for generating an N-bit codeword, a mapping step for creating complex signals, and a bit length adjustment step to ensure the second bit sequence has a length that is a multiple of X+Y bits, facilitating the MIMO scheme's implementation with LDPC coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC coding is applied to MIMO scheme, then error correction capability is improved, but bit length mismatch occurs between coding schemes
Solution Approach 1:
The N-bit codeword from LDPC coding is segmented into multiple bit sequences, each of which is independently processed and mapped to complex signals for MIMO transmission. This segmentation allows the coded bits to be distributed across multiple transmission streams while maintaining the error correction benefits of LDPC coding.
Solution Approach 2:
A bit sequence generation unit acts as an intermediary between the LDPC encoder and the MIMO modulator. This intermediary processes the N-bit codeword to generate bit sequences with lengths that are multiples of (X+Y), where X and Y are the numbers of bits required for generating the first and second complex signals respectively. This intermediary layer resolves the bit length incompatibility between LDPC coding and MIMO transmission requirements.
2Adaptability or versatility
If different numbers of bits are used to generate first and second complex signals, then MIMO transmission flexibility is improved, but bit length alignment becomes complex
Solution Approach 1:
The system dynamically adjusts the bit length parameter of the bit sequences to be generated, ensuring that the total bit length is a multiple of (X+Y). This parameter adjustment is performed by the bit sequence generation unit, which can flexibly handle different values of X and Y while maintaining proper alignment for MIMO transmission.
Solution Approach 2:
The bit sequence generation unit automatically performs bit length adjustment without requiring external intervention. It self-regulates the bit sequence length to match the requirements of the MIMO modulator, thereby simplifying the overall system operation despite the underlying complexity of aligning different bit lengths.
Data Source
AI summary
An encoder outputs a first bit sequence having N bits. A mapper generates a first complex signal s1 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.