Sparse Superposition Coding for Spectrally Efficient URLLC Messages
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Solution Overview
Problem
Conventional low density parity check (LDPC) and polar coding techniques used in 5G NR for eMBB data and control channels result in lower spectral efficiency for Ultra-Reliable and Low-Latency Communication (URLLC) due to reduced code rates and modulation orders, which are not designed for short message transmission, leading to smaller spectral efficiency compared to eMBB.
Innovation Solution
A transmitter device and receiver device employing a sparse superposition coding scheme with a quasi-orthogonal projection matrix, where the projection matrix is a concatenation of submatrices with orthogonal columns and correlated columns less than 1/M, allowing for efficient transmission and decoding of information messages by superposing and interleaving selected columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC/polar codes are used for URLLC transmission, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the fundamental coding parameter from conventional LDPC/polar codes to Sparse Superposition Coding (SSC), which uses a different mathematical approach based on sparse signal representation. This parameter change allows the system to achieve both high reliability and high spectral efficiency by exploiting the sparsity property of URLLC traffic patterns
Solution Approach 2:
The patent combines multiple technical elements into a composite coding scheme: sparse code selection, superposition modulation, and iterative decoding. This composite approach integrates the strengths of different techniques to simultaneously achieve reliability and spectral efficiency that neither conventional code alone can provide
2Reliability
If code rate is decreased for URLLC, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the code rate parameter from low (conventional for URLLC) to high (up to 0.5 or higher), fundamentally altering how reliability is achieved. Instead of using low code rates with redundant parity bits, the system uses high code rates with sparse superposition, where reliability comes from the selective activation of sparse code components rather than extensive redundancy
3Reliability
If modulation order is decreased for URLLC, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the modulation order parameter from low (conventional for URLLC) to high (e.g., 64-QAM, 256-QAM), fundamentally changing how reliability is achieved. Instead of using robust but spectrally inefficient low-order modulation, the system uses high-order modulation combined with sparse superposition coding, where the sparsity provides the reliability protection rather than the modulation robustness
Data Source
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AI summary
The invention relates to a transmitter device and a receiver device for efficient transmission of information messages. The transmitter device (100) superpose a selected subset of columns of a projection matrix (F) based on an information message (m) so as to obtain a signal for transmission (z). The signal (z) is transmitted to the receiver device (300. The receiver device (300) performs iterative successive interference cancellation on a received signal (r) based on a projection matrix (F) so as to obtain a subset of the columns of the projection matrix (F) and therefrom obtains a recovered information message (m) based on the subset of the columns of the projection matrix (F). Thereby, it is provided a sparse superposition coding scheme with quasi-orthogonal projection matrix achieving good performance in respect of spectral efficiency. Furthermore, the invention also relates to corresponding methods and a computer program.