A New Galaxy Constellation for Phase Noise Dominated Terahertz Communication

Terahertz (THz) communication technology, with its ultra-high bandwidth, high transmission rate, and low latency characteristics, has become one of the key technologies for future 6G mobile communication. However, as the frequency band increases, phase noise between transceiver channels becomes more pronounced, significantly limiting the performance of THz communication systems. This paper presents a novel galaxy quadrature amplitude modulation (GQAM) design to mitigate the impact of phase noise for phase noise dominated THz communication. By adjusting the distribution of constellation points on the two-arm spiral, adaptive modulation can be achieved under different levels of phase noise. Furthermore, we designed a demodulation scheme that takes into account the impact of phase noise and developed a neighboring constellation points search algorithm to simplify the demodulation process for higher-order constellations. Simulation and experimental results indicate that our designed constellation can effectively overcome the impact of phase noise in various noise environments, and it outperforms other constellations such as quadrature amplitude modulation (QAM) and spiral quadrature amplitude modulation (SQAM).