Multiband Delta-Sigma Digitization for Mobile Fronthaul

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional mobile fronthaul (MFH) technologies, such as analog MFH based on radio-over-fiber (RoF) and digital MFH based on common public radio interface (CPRI), struggle to keep pace with the increasing wireless traffic growth, particularly in supporting high-order modulation formats and multi-radio access technologies (multi-RATs) due to spectral inefficiency and compatibility issues.

Innovation Solution

The implementation of multiband delta-sigma digitization techniques in MFH networks, which enable the aggregation and digitization of multiple RATs like 4G-LTE, Wi-Fi, and 5G-NR without frequency conversion, using delta-sigma analog-to-digital converters (ADCs) that oversample, noise-shape, and filter signals to eliminate quantization noise, thereby improving spectral efficiency and reducing the need for digital-to-analog converters (DACs) and RF devices at remote radio heads (RRHs).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional digital MFH based on CPRI is used, then digitization of wireless services is achieved, but spectral efficiency is insufficient to keep pace with increasing wireless traffic growth

Engineering Contradiction:

Improvespectral efficiencyVSAvoidwireless traffic capacity

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent changes the digitization parameters by using delta-sigma ADCs with oversampling rates greater than twice the Nyquist rate, compared to the conventional Nyquist-rate sampling in CPRI. This parameter change enables more efficient spectral utilization while maintaining the required signal fidelity for high-order modulation formats.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system dynamically adapts to support multiple radio access technologies (4G-LTE, Wi-Fi, 5G-NR) with different spectral requirements through multiband delta-sigma digitization, allowing the MFH network to optimize spectral efficiency for varying traffic demands and service types.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multiple RATs are aggregated in heterogeneous MFH networks, then service diversity and traffic offloading are improved, but clock rate compatibility and time synchronization challenges arise

Engineering Contradiction:

Improvemulti-RAT aggregation capabilityVSAvoidclock rate compatibility and synchronization

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The multiband delta-sigma digitization system provides a universal digitization interface that can handle multiple RATs (4G-LTE, Wi-Fi, 5G-NR) with different clock rates and spectral characteristics through a unified architecture, eliminating the need for separate digitization paths for each RAT and thereby reducing synchronization complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If high-order modulation formats are supported to increase data rate, then wireless traffic capacity increases, but resilience against nonlinear impairments decreases

Engineering Contradiction:

Improvedata rate capacityVSAvoidresilience against nonlinear impairments

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary noise shaping and filtering in the delta-sigma ADC to push quantization noise out of the signal band before transmission. This preliminary action ensures that high-order modulation signals are transmitted with reduced in-band noise, maintaining resilience against nonlinear impairments while supporting high data rates.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances spectral efficiency, reduces costs and complexity, and facilitates the deployment of 5G small cells by enabling seamless carrier aggregation of multiple RATs, overcoming clock rate compatibility and time synchronization challenges, while supporting a wide range of wireless services with improved resilience against nonlinear impairments.

Implementation Method 1

oversampling the aggregated signal at rate equal to an oversampling rate times the Nyquist sampling rate to generate an oversampled signal and quantization noise

Methodology Applied

Scientific EffectOversampling:

Implementation Method 2

noise shaping the oversampled signal to push the quantization noise into out-of-band frequency spectra corresponding to respective spectral portions between the plurality of different signal bands

Methodology Applied

Scientific EffectNoise shaping:

Implementation Method 3

filtering the noise shaped signal to remove the out-of-band quantization noise from the plurality of different signal bands

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Data Source

PatentUS11469822B1Systems and methods for multiband delta sigma digitization

Publication Date: 2022.10.11 CABLE TELEVISION LAB INC

AI summary

A digital mobile fronthaul (MFH) network includes a baseband processing unit (BBU) having a digitization interface configured to digitize, using delta-sigma digitization, at least one wireless service for at least one radio access technology. The network further includes a transport medium in operable communication with the BBU. The transport medium is configured to transmit a delta-sigma digitized wireless service from the BBU. The network further includes a remote radio head (RRH) configured to operably receive the delta-sigma digitized wireless service from the BBU over the transport medium.