Terahertz Wireless CDMA Communication using Resonant Tunneling Diodes

This paper describes a code division multiple access (CDMA) system operating in the Terahertz (THz) band using resonant tunneling diode (RTD) technology. RTDs are a promising technology enabling the efficient generation and detection of THz-band signals while consuming very low power. Meanwhile, CDMA systems facilitate the transmission of multiple-users signals in low signal to noise ratio (SNR) conditions. The developed THz system consists of real-time CDMA waveform transmission at 3.1 Gchip/s for up to 7 users over a distance of 7.5cm at 345 GHz with off-line decoding of the digitally-sampled signals. The system employs optical modified prime codes (MPC) with unipolar (0,1) sequences that were originally designed for CDMA optical-fiber networks with simplified detection. Experimental results demonstrate the viability of CDMA transmission using RTDs with chip-level on-off-keying (OOK).