Digital mobile fronthaul employing differential pulse code modulation with suppressed quantization noise

Area of Science:

• Telecommunications Engineering
• Signal Processing
• Optical Communications

Background:

• Mobile fronthaul networks are critical for 5G deployment.
• Existing Common Public Radio Interface (CPRI) faces bandwidth limitations.
• Efficient data compression and transmission are needed for advanced mobile networks.

Purpose of the Study:

• To propose and demonstrate a digital mobile fronthaul architecture based on Differential Pulse Code Modulation (DPCM).
• To improve data compression and reduce quantization noise in mobile fronthaul systems.
• To evaluate the performance of the DPCM-based fronthaul for various modulation schemes and future mobile standards.

Main Methods:

• Implementation of a DPCM encoding process with a linear predictor.
• Experimental validation using a 20 km, 15-Gbaud/λ Pulse Amplitude Modulation (PAM4) intensity modulation and direct detection system.
• Testing with various Quadrature Amplitude Modulation (QAM) levels and Universal Filtered Multicarrier (UFMC) signals.

Main Results:

• Achieved a prediction gain of 7-8 dB by suppressing quantization noise.
• Supported 4, 16, 64, and 256 QAM with 3-6 quantization bits at 30.72 MSa/s.
• Enabled 1024 QAM and 4096 QAM transmission with Error Vector Magnitude (EVM) below 1% and 0.5% using 8-9 quantization bits.
• Demonstrated increased antenna-carrier (AxC) capacity and reduced EVM compared to CPRI.
• Successfully transmitted Universal Filtered Multicarrier signals.

Conclusions:

• The proposed DPCM-based fronthaul architecture is feasible and offers superior performance over CPRI.
• The DPCM system effectively supports high-order QAM and advanced waveforms like UFMC.
• This technology provides a promising solution for future mobile network fronthaul requirements, including 5G and beyond.