Multi-Level Modulator Architecture for Low-Latency Short-Reach Links
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Solution Overview
Problem
Existing communication modulators for high-speed applications over short-reach links, such as 40 G/100 G communication over copper cables or single-mode fiber, suffer from high complexity and latency, making them unsuitable for efficient data transmission due to excessive redundancy and latency introduced by interleaving processes.
Innovation Solution
A multi-level modulator is introduced, featuring a symbol mapper and a multi-level encoder with an inner and outer encoder, where the information block size of the inner encoder matches the field size of the outer encoder, reducing complexity and latency by confining errors to symbol boundaries and omitting interleaving, thus reducing hardware complexity and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interleaving is used to protect against burst errors, then error correction capability is improved, but latency and hardware complexity increase
Solution Approach 1:
The patent extracts the error protection function from the interleaving process and implements it through a multi-level coding scheme where inner codes protect against burst errors and outer codes provide additional redundancy, eliminating the need for traditional interleaving structures and their associated latency
Solution Approach 2:
The patent segments the error correction function into multiple levels of coding (inner and outer codes) that operate at different stages of the transmission process, allowing error protection to be achieved without requiring the complete interleaving of entire data blocks
2Reliability
If interleaving is used to protect against burst errors, then error correction capability is improved, but hardware complexity increases
Solution Approach 1:
The patent removes the complex interleaving hardware and replaces it with a multi-level coding architecture using inner and outer codes that achieve similar error protection with simpler, more modular computational structures
Solution Approach 2:
The patent divides the error correction function into separate inner and outer coding stages, each handling specific aspects of error protection, which simplifies the overall hardware design compared to a monolithic interleaving system
3Loss of time
If short codes are used to reduce latency, then processing speed is improved, but error correction capability may be reduced
Solution Approach 1:
The patent segments the error correction function into inner codes that use short code lengths for low-latency processing and outer codes that provide additional error protection, achieving both low latency and high reliability through multi-level coding
Solution Approach 2:
The patent implements nested coding where outer codes are applied to the outputs of inner codes, creating a hierarchical structure where short inner codes provide rapid error correction and outer codes provide additional protection, maintaining both low latency and high reliability
Data Source
AI summary
For some applications such as high-speed communication over short-reach links, the complexity and associated high latency provided by existing modulators may be unsuitable. According to an aspect, the present disclosure provides a modulator that can reduce latency for applications such as 40 G/100 G communication over copper cables or SMF. The modulator has a symbol mapper for mapping a bit stream into symbols, and a multi-level encoder including an inner encoder and an outer encoder for encoding only a portion of the bit stream. In some implementations, the multi-level encoder is configured such that an information block size of the inner encoder is small and matches a field size of the outer encoder. Therefore, components that would be used to accommodate larger block sizes can be omitted. The effect is that complexity and latency can be reduced. According to another aspect, the present disclosure provides a demodulator that is complementary to the modulator.