Delta-Sigma Carrier Digitization Without RF Conversion
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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 with CPRI, which limits their ability to handle the increasing bandwidth demands of 5G heterogeneous networks.
Innovation Solution
The implementation of a 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
Engineering Contradiction Analysis
1Reliability
If conventional CPRI digitization is used, then digital MFH networks can transmit wireless services, but spectral efficiency is low and compatibility issues arise with high-order modulation formats
Solution Approach 1:
The patent changes the digitization parameters by using delta-sigma modulation instead of conventional CPRI, oversampling the signal at a higher rate and applying noise shaping to push quantization noise out of band. This allows compatibility with high-order modulation formats while improving spectral efficiency through more efficient quantization of the oversampled signal.
2Adaptability or versatility
If multiple RATs are aggregated in heterogeneous MFH networks, then service diversity increases, but system complexity and bandwidth requirements increase
Solution Approach 1:
The patent merges multiple radio access technologies into a single heterogeneous MFH network using a unified delta-sigma digitization interface. By aggregating different RATs at the BBU level with a common digitization architecture, the system achieves multi-RAT support without proportionally increasing complexity, as the same oversampling and noise-shaping techniques apply to all aggregated services.
3Productivity
If delta-sigma digitization with oversampling is implemented, then spectral efficiency improves and quantization noise is pushed out of band, but processing requirements increase
Solution Approach 1:
The patent extracts quantization noise from the signal band by using noise shaping that pushes the noise spectrum out of band. This allows the use of fewer quantization bits while maintaining signal fidelity, reducing processing requirements compared to conventional methods that would require more bits to achieve the same noise floor without oversampling.
Data Source
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.