Multi-Antenna LDPC Coding With Per-Stream Code Rate Adaptation
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Solution Overview
Problem
LDPC codes, despite their potential for low error rates, face computational inefficiencies due to high-density generator matrices, making them impractical for many applications, and multi-antenna communication systems face challenges with unequal channel conditions.
Innovation Solution
Implementing a parity check matrix with a quasi-cyclic structure and using singular value decomposition (SVD) beamforming to transform MIMO systems into parallel channels with different SNR levels, enabling efficient encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC codes are used for error correction, then error rates are reduced, but computational complexity increases due to high-density generator matrices
Solution Approach 1:
The patent segments the high-density generator matrix into multiple lower-density sub-matrices, allowing the encoding process to be divided into simpler operations that can be performed with reduced computational complexity while maintaining the error correction performance of LDPC codes
Solution Approach 2:
The patent changes the structural parameters of the generator matrix from high-density to low-density form, transforming the encoding operation into a more computationally efficient process while preserving the code's ability to correct errors effectively
2Reliability
If multi-antenna systems are deployed to improve communication reliability, then error correction capability is enhanced, but channel condition variability increases
Solution Approach 1:
The patent applies different code rates to different spatial streams based on their respective channel conditions, allowing each stream to be optimized for its local channel quality rather than using a uniform code rate across all antennas
Solution Approach 2:
The patent dynamically adjusts the code rate for each spatial stream based on real-time channel condition assessment, enabling the system to adapt to varying channel qualities across different antennas and improve overall communication reliability
3Adaptability or versatility
If multiple code rates are implemented for different spatial streams, then channel adaptation is improved, but system complexity increases
Solution Approach 1:
The patent designs a unified encoding framework that can handle multiple code rates within a single LDPC code structure, allowing the same encoder to serve multiple spatial streams with different code rates without requiring separate encoders for each stream
Data Source
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AI summary
In some implementations, an apparatus may include a plurality of transmitters (122) and one or more processors (2010). The one or more processors (2010) may identify a plurality of wireless channels corresponding to the plurality of transmitters (122) for transmitting respective data streams. The one or more processors (2010) may determine, based at least on a difference in signal quality between the plurality of wireless channels, respective target code rates for the plurality of wireless channels. The respective target code rates may be different from each other and different from a base code rate of a low density parity check (LDPC) code. The one or more processors (2010) may encode, by an LDPC encoder (1106) using the LDPC code with the base code rate, the respective data streams to generate respective encoded data streams at the respective target code rates. The plurality of transmitters (122) may transmit the respective encoded data streams via respective wireless channels.