Special cascade LMS equalization scheme suitable for 60-GHz RoF transmission system.

Area of Science:

• Optical communications
• Wireless communications
• Signal processing

Background:

• 60-GHz millimeter-wave (mm-wave) radio over fiber (RoF) systems face challenges with signal distortion from optical and wireless channels.
• Existing equalization methods may not efficiently address the combined impairments of RoF systems.

Purpose of the Study:

• To design and evaluate a novel cascade least mean square (LMS) equalizer for 60-GHz mm-wave RoF systems.
• To separately compensate for linear and nonlinear distortions in optical and wireless links.
• To improve the performance and efficiency of RoF systems.

Main Methods:

• A cascade LMS equalizer with two sub-equalizers was designed for optical and wireless channel compensation.
• Theoretical and experimental investigations were conducted to optimize sub-equalizer parameters.
• System performance was evaluated using 5-Gbps BPSK signals over a 10-km fiber and 1.2-m wireless link.

Main Results:

• The cascade LMS equalizer demonstrated a faster convergence speed, requiring half the training sequence length compared to traditional LMS equalizers.
• The proposed equalizer successfully transmitted data under the forward error correction (FEC) limit of 10^-3.
• Significant improvements in power sensitivity were observed: 4dBm for Back-to-Back (BTB) and 1dBm for the 10-km fiber/1.2-m wireless link configurations.

Conclusions:

• The developed cascade LMS equalizer is effective in mitigating distortions in 60-GHz mm-wave RoF systems.
• The novel equalization scheme offers advantages in convergence speed and power sensitivity.
• This approach enables reliable high-speed data transmission in integrated optical-wireless systems.