30.2 km D-band transmission of delta–sigma-modulated signals with IQ-MRC reception

In this Letter, we propose and experimentally demonstrate a novel, to the best of our knowledge, IQ-receiver architecture for high-capacity D-band wireless transmission, enabled by delta-sigma modulation (DSM). An improved IQ-maximal-ratio-combining (IQ-MRC) algorithm is introduced to mitigate performance degradation induced by frequency-selective fading and IQ imbalance, providing an additional signal-to-noise ratio (SNR) gain of approximately 1 dB. Using the proposed system, we demonstrate 30.2 km transmission of an 8 Gbaud DSM 256 quadrature amplitude modulation (QAM) signal with a net data rate of 13.91 Gb/s, achieving a BER below the threshold of 15% overhead soft decision forward error correction (SD-FEC). To the best of our knowledge, this is the longest reported transmission distance for DSM-modulated signals in the D-band.