Real-Time Simplified Coherent Photon-Assisted Fiber-Terahertz Integrated System Using Parallel Kramers-Kronig Receiver and FPGA Operation

Simplified coherent detection presents a promising strategy for lowering receiver costs in photonics-aided terahertz (THz) wireless communication systems that operate at ultra-high data rates. However, the envelope detection is inherently limited by signal–signal beat interference (SSBI)-induced SNR degradation. While the Kramers–Kronig (KK) receiver configuration effectively mitigates SSBI, its practical deployment is hindered by the difficulty of implementing the Hilbert transform and nonlinear functions under low computational complexity. In this paper, A FPGA-based simplified parallel KK (SP-KK) receiver architecture is proposed and experimentally demonstrated. The key contribution is a design that approximates the nonlinear operation via a Taylor series expansion and incorporates a computationally efficient, multiplication-free FIR filter to execute the Hilbert transform. The SP-KK receiver's performance was evaluated utilizing 16QAM single-sideband discrete multitone (DMT) signals across a converged 10-km fiber and 30-m wireless link operating at 322 GHz. The results demonstrate comparable performance to a conventional parallel KK receiver, with the primary advantage being a significant conservation of on-chip DSP resources. This work highlights the potential of integrating THz photonic components, electronic hardware, and sophisticated DSP algorithms to realize real-time simplified coherent high-speed wireless communication. This will provide us with a viable pathway toward future 6G mobile fronthaul and backhaul solutions.