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

Abstract

Compared to the traditional Volterra nonlinear equalizer (VNE), the multi-input, multioutput (MIMO)–VNE is capable of addressing the signal degradation caused by higher order cross-talk. 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 article. 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.