A 10-Gbit/s Wireless Communication Link Using 16-QAM Modulation in 140-GHz Band

This paper describes a 140-GHz wireless link whose maximum transmission data rate is 10 Gbit/s. A sub-harmonic mixer and multiplier based on Schottky barrier diodes, a waveguide H ladder bandpass filter, a Cassegrain antenna, and other components have been developed to construct a high-performance transmitting and receiving front end. 16 quadrature amplitude modulation has been adopted to improve the spectrum efficiency to 2.86-bit/s/Hz. A 32-way parallel demodulation architecture based on frequency-domain implementation of the matched filter and timing phase correction is proposed. An adaptive blind equalization algorithm is also realized to enhance the tolerance for channel distortion. The modulated signal is centered at 140.3 GHz with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${-}{\hbox{5}}$</tex> </formula> -dBm output power. This link succeeded in transmission of a 10-Gbit/s signal over a 1.5-km distance with a bit error rate of 1e-6 in non-real-time mode. The measured 99.99% power bandwidth of the 10-Gbit/s signal is 3.6 GHz. The lowest acceptable signal noise rate per bit ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$E_{ b}/N_{0}$</tex></formula> ) is 15 dB. This link also transmitted a 2-Gbit/s real-time signal with lowest <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm BER} = 1.80{ e}-11$</tex></formula> .