LDPC Code Optimization for Bandwidth-Constrained Equalized Transport
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Solution Overview
Problem
Conventional communication systems face limitations in achieving high spectral efficiency and capacity due to bandwidth constraints, leading to increased complexity and power consumption in equalizers, especially in systems with high throughput and wideband applications.
Innovation Solution
The introduction of bandwidth-constrained equalized transport (BCET) systems, which intentionally introduce memory into signals through pulse-shaping filters and utilize optimized low-density parity-check (LDPC) error control codes, along with trellis-based equalization and turbo equalization loops, to enhance information rates and reduce system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional communication systems use traditional modulation formats without memory, then the system design is simpler, but the spectral efficiency cannot approach the Shannon limit
Solution Approach 1:
The patent changes the fundamental parameter of the channel by intentionally introducing memory through pulse-shaping filters, transforming the memoryless channel into a channel with controlled inter-symbol interference. This parameter change enables the system to achieve higher spectral efficiency by operating closer to the Shannon limit while managing complexity through optimized LDPC codes designed specifically for the introduced memory structure
Solution Approach 2:
The patent replaces traditional complex equalization mechanisms with an optimized error control coding scheme. Instead of using sophisticated equalizers to handle channel memory effects, the system uses LDPC codes with degree distributions optimized for the intentionally introduced memory, substituting a coding-based solution for a traditional equalization-based approach
2Reliability
If iterative decoding is used to improve performance, then the reliability estimate improves with each iteration, but the processing complexity and latency increase
Solution Approach 1:
The patent optimizes the LDPC code parameters, specifically the degree distribution of variable and check nodes, to achieve rapid convergence of the iterative decoding process. By carefully selecting these parameters, the system achieves excellent error correction performance with fewer iterations, thereby reducing processing complexity and latency while maintaining high reliability
Solution Approach 2:
The patent performs preliminary optimization of the LDPC code structure and parameters before the actual communication takes place. The degree distributions are pre-calculated and optimized for the specific channel conditions and performance requirements, allowing the iterative decoder to converge quickly without requiring complex real-time adjustments during operation
3Productivity
If bandwidth constraint is imposed to increase spectral efficiency, then more information can be transmitted per Hz, but the equalizer complexity and power consumption increase
Solution Approach 1:
The patent substitutes traditional equalization mechanisms with optimized error control coding to handle bandwidth constraints. Instead of using power-hungry equalizers to mitigate inter-symbol interference caused by bandwidth limitation, the system uses LDPC codes with degree distributions optimized for the constrained channel, achieving high information rates with lower power consumption
Solution Approach 2:
The patent changes the approach to handling bandwidth constraints by intentionally introducing controlled memory through pulse-shaping filters and compensating with optimized coding parameters. This parameter change allows the system to achieve high spectral efficiency while managing power consumption through efficient LDPC decoding rather than complex equalization
4Productivity
If intentional memory is introduced through pulse-shaping filter to increase information rate, then the spectral efficiency improves, but the channel becomes more difficult to equalize
Solution Approach 1:
The patent replaces traditional equalization mechanisms with optimized error control coding to handle the intentionally introduced memory. Instead of using complex equalizers to reverse the pulse-shaping filter effects, the system uses LDPC codes with degree distributions specifically optimized for channels with the introduced memory structure, achieving high information rates without the complexity of sophisticated equalization
Solution Approach 2:
The patent converts the harmful effect of inter-symbol interference into a beneficial structure by intentionally introducing controlled memory through pulse-shaping filters. The resulting channel structure, while more difficult for traditional equalizers, is perfectly matched to the optimized LDPC codes, turning the potential harm into a benefit that enables higher spectral efficiency
Data Source
AI summary
In some embodiments, a bandwidth constrained equalized transport (BCET) communication system comprises a transmitter that transmits a signal, a communication channel that transports the signal, and a receiver that receives the signal. The transmitter can comprise a pulse-shaping filter that intentionally introduces memory into the signal, and an error control code encoder that is a low-density parity-check (LDPC) error control code encoder. The error control encoder comprises code that is optimized based on the intentionally introduced memory into the signal, a code rate, a signal-to-noise ratio, and an equalizer structure in the receiver. In some embodiments, the communication system is bandwidth constrained, and the transmitted signal comprises an information rate that is higher than for an equivalent system without intentional introduction of the memory at the transmitter.