Beyond 500 GHz THz Wireless Links Based on Heterodyne Photo-mixing and Absolute Operation Pruned Two-Stage MIMO Volterra

Compared to the traditional Volterra nonlinear equalizer (VNE), the multi-input, multi-output (MIMO) VNE is capable of addressing the signal degradation caused by higher-order crosstalk. Naturally, the gains from the MIMO architecture are at the cost of doubling the amount of computation. To reduce the calculation workload, based on the two-stage serial-parallel MIMO architecture, the absolute operation of the cross-beating terms and the pruning technique, an extremely low-complexity MIMO VNE, namely absolute-term pruned two-stage (AT-P-2S) MIMO VNE, has been proposed in this research. With the proposed AT-P-2S MIMO VNE and optical mixing technique, terahertz wave transmission over 500 GHz is successfully demonstrated. The experimental results show that the AT-P-2S-MIMO VNE demonstrates very comparable BER performance to the MIMO VNE, and can achieve more than 4% capacity improvement in the beyond-500 GHz band. Meanwhile, in contrast to MIMO VNE, AT-P-2S MIMO VNE can reduce the equalizer real multiplication operation by more than 94%. By striking a balance between performance and complexity, the proposed AT-P-2S- MIMO VNE offers an appealing solution to enhance the efficiency and effectiveness of future communication systems.