Performance of channel codes for terahertz wireless communications in the Internet of Space

Abstract

This paper investigates channel coding for terahertz (THz) wireless communications in space-oriented Internet-of-Space scenarios, where ultra-high data-rate transmission must be supported under severe propagation loss, stringent link-budget constraints, and practical non-idealities. An impairment-aware THz space-link framework is developed by using free-space path loss and additive white Gaussian noise as the baseline propagation and noise backbone, while incorporating representative practical and environmental effects, including beam pointing error, residual carrier frequency offset, oscillator phase noise, hardware- and antenna-gain uncertainty, solar-induced receiver noise-temperature increase, and plasma-induced attenuation and scintillation. Based on this framework, five representative channel coding schemes, namely Turbo, Polar, Hamming, Reed-Solomon, and Convolutional codes, are comparatively evaluated under QPSK modulation. Their bit error rate performance is studied with respect to code rate, equivalent SNR budget, transmission distance, carrier frequency, minimum transmit-side power budget, and impairment severity. The results show that lower code rates generally improve reliability, whereas higher carrier frequencies and longer transmission distances impose more stringent link-budget requirements. Among the evaluated schemes, Polar and Turbo codes achieve the most competitive overall performance. Polar coding provides the lowest BER in several short-distance and moderate-frequency settings, while Turbo coding exhibits stronger robustness when the carrier frequency exceeds 1 THz. The analysis further clarifies that the Shannon benchmark should be interpreted as a receiver-side theoretical reference, whereas free-space path loss and impairment-related penalties determine the transmit-side budget required to achieve the target reliability. These results indicate that robust channel coding remains an essential reliability layer for future THz space communication systems, even when sensing-assisted beam alignment, semantic-aware transmission, or integrated sensing and communication mechanisms are adopted.