Dirty Paper Coding With Probabilistic Shaping for Low-SNR Links
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Solution Overview
Problem
Existing DPC schemes face performance degradation at low SNR and high computational complexity, especially when using scalar modulo operations or trellis-coded quantization, which limits their effectiveness in noisy channels with known interference.
Innovation Solution
The proposed solution involves an encoding device and decoding device that utilize probabilistic shaping based on effective interference, allowing for the use of standard channel codes and low-complexity scalar functions to achieve improved performance, especially at low spectral efficiencies and low SNR, by determining symbol probabilities and mapping them into transmit signals using a scalar function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If scalar modulo operation is used for DPC, then device complexity is reduced, but performance degrades at low SNR
Solution Approach 1:
The patent changes the distribution parameter of transmit symbols from uniform to non-uniform (probabilistic shaping), which improves performance at low SNR while maintaining the simplicity of scalar modulo operation. The transmit symbols are generated with a non-uniform distribution that matches the channel conditions, thereby resolving the contradiction between low complexity and low-SNR performance.
2Reliability
If trellis-coded quantization is used for DPC, then performance is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the complex trellis-coded quantization component from the DPC system, replacing it with a simpler probabilistic shaping approach using non-uniform symbol distribution. This extraction eliminates the high computational complexity of trellis decoding while maintaining performance through the non-uniform distribution design.
Solution Approach 2:
The patent replaces the expensive and complex trellis-coded quantization with a cheaper alternative - probabilistic shaping using non-uniform symbol distribution. This disposable approach sacrifices the sophisticated structure of TCQ but achieves comparable performance with much lower complexity, suitable for practical implementations.
3Ease of operation
If uniform distribution is used for data symbols, then ease of operation is improved, but performance degrades with scalar modulo operation
Solution Approach 1:
The patent changes the distribution parameter of data symbols from uniform to non-uniform (probabilistic shaping). This parameter change maintains the simplicity of operation while significantly improving performance at low spectral efficiency and low SNR by optimizing the symbol distribution to match channel conditions.
Data Source
AI summary
The present disclosure relates to a dirty paper coding (DPC) scheme for a wireless communication system. One example encoding device obtains symbol probabilities for symbols of a symbol sequence given an effective interference based on a target distribution of symbols of a transmit signal, encodes a message into the symbol sequence based on the symbol probabilities, and then obtains the transmit signal based on a mapping of the symbol sequence and the effective interference using a scalar function. One example decoding device obtains a receive signal, obtains a symbol sequence based on the receive signal and a scaling factor using a scalar function, and then decodes the symbol sequence to obtain a message.