Delta-Sigma Carrier Digitization Without Remote DACs

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional digital mobile fronthaul (MFH) networks face challenges in supporting high-order modulation formats and multiple radio access technologies (RATs) due to low spectral efficiency and compatibility issues, particularly with CPRI, which is cost-prohibitive and lacks support for Wi-Fi and 5G-NR.

Innovation Solution

The implementation of a multiband delta-sigma digitization interface that oversamples and noise-shapes signals to push quantization noise out of band, allowing for simultaneous digitization of multiple RATs without frequency conversion, thereby eliminating the need for DAC and RF devices at remote radio heads and enhancing spectral efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional digital MFH networks use CPRI for digitization, then compatibility with existing systems is maintained, but spectral efficiency is low and cost is prohibitive

Engineering Contradiction:

ImprovecompatibilityVSAvoidspectral efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the digitization parameters from conventional Nyquist sampling to oversampling at a rate higher than twice the signal bandwidth. This parameter change enables delta-sigma modulation which achieves higher spectral efficiency by pushing quantization noise out of the signal band through noise shaping, while maintaining compatibility through standardized interfaces

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the conventional CPRI digitization mechanism with a delta-sigma digitization mechanism. This replacement uses oversampling and noise-shaping techniques to achieve superior spectral efficiency compared to the mechanical/electrical CPRI interface, while eliminating the need for complex DAC and RF devices at remote radio heads

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If conventional digitization methods are used, then implementation is straightforward, but support for high-order modulation formats and multiple RATs is limited

Engineering Contradiction:

Improveimplementation simplicityVSAvoidsupport for multiple RATs

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements a universal delta-sigma digitization interface that can simultaneously handle multiple radio access technologies (4G-LTE, Wi-Fi, 5G-NR) and high-order modulation formats. The oversampling and noise-shaping mechanism provides a unified approach that adapts to different RATs without requiring separate digitization paths, enhancing versatility while maintaining implementation simplicity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces dynamic adaptability through the delta-sigma digitization interface that can dynamically adjust to different modulation formats and RAT requirements. The noise-shaping filter characteristics can be adapted to push quantization noise away from signal bands of different widths and characteristics, enabling flexible support for multiple standards

Inventive Principle:

Principle #15Dynamics

3Productivity

If delta-sigma digitization with oversampling is implemented, then spectral efficiency is enhanced, but device complexity increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoiddigitization interface complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates complex components from the remote radio head by implementing delta-sigma digitization at the baseband unit. The oversampling and noise-shaping processing removes the need for complex DAC and RF devices at the remote radio head, centralizing the complexity in the baseband unit where it can be more efficiently managed

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses digital copying and processing of the oversampled signal through noise-shaping filters to achieve the desired spectral efficiency. Instead of requiring complex analog components, the system uses digital signal processing to replicate and shape the noise spectrum, achieving high spectral efficiency with simplified hardware

Inventive Principle:

Principle #26Copying

4Reliability

If CPRI is used for digitization, then existing infrastructure is compatible, but support for Wi-Fi and 5G-NR is lacking

Engineering Contradiction:

Improveinfrastructure compatibilityVSAvoidsupport for Wi-Fi and 5G-NR

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a universal delta-sigma digitization interface that provides multi-functionality to support multiple radio access technologies including 4G-LTE, Wi-Fi, and 5G-NR. The interface maintains compatibility with existing infrastructure through standardized connections while extending capability to support newer standards through its flexible oversampling and noise-shaping mechanism

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11025461B2Systems and methods for delta-sigma digitization

Publication Date: 2021.06.01 CABLE TELEVISION LAB INC

AI summary

A baseband processing unit includes a baseband processor configured to receive a plurality of component carriers of a radio access technology wireless service, and a delta-sigma digitization interface configured to digitize at least one carrier signal of the plurality of component carriers into a digitized bit stream, for transport over a transport medium, by (i) oversampling the at least one carrier signal, (ii) quantizing the oversampled carrier signal into the digitized bit stream using two or fewer quantization bits.