The world’s-first compact transceiver for terahertz wireless communication using the 300-GHz band—with transmission rate of several-dozen gigabits per second—was developed and experimentally demonstrated high-speed data transmission.

In this experiment, an InP-based high-electron-mobility transistor (InP-HEMT) was used as an ultrahigh-speed device and incorporated in a high-frequency transceiver circuit designed as an integrated circuit (IC). In this manner, a compact transceiver for terahertz wireless communication using the 300-GHz band was created. The transmitter enables 20-Gbps data transmission as an integrated architecture connecting (via a waveguide) a metal package housing the IC and an antenna (see Figure 1). Moreover, under the assumption that the receiver will be mounted in a smartphone-sized terminal, mounting the IC in the antenna-integrated metal package resulted in an overall size of 1 cc (previously reported 1, previously reported 2). The receiver demodulates a 20-Gbps wireless signal (received via the wireless section) and outputs it as a data signal (see Figure 2). In addition, as for radiowave propagation and measurement technology concerning the 300-GHz band, high-speed data transfer was verified by an experiment performed in an anechoic chamber (see Figure 3).

In this verification experiment, the transmitter and a signal processor for forward error correction (FEC) etc. (both developed by NTT), the receiver (developed by Fujitsu), and the radiowave propagation and measurement technology (developed by NICT) were brought together in the configuration shown in Figure 4. With the developed transmitter and receiver set facing each other, 20-Gbps data transfer was achieved. As a result, as for transmission distances exceeding 1 m, the possibility of error-free transmission was confirmed (see Figure 5).

Furthermore, an experiment on polarization-multiplexing transmission using two transceiver sets and a polarized waves perpendicular to each other was performed, and the results of the experiment confirmed that 40-Gbps data transfer is possible. These experiments confirmed sufficient performance as a wireless device transceiver and the utility of the developed technology.
 

With the developed transmitter installed in an information terminal, and the matching developed receiver installed in a smartphone-sized terminal, a verification experiment simulating a service for downloading data (by touching the smartphone-sized terminal on the information terminal) was performed (see Figures 6, 7, and 8). In this experiment, video files stored in a PC on the transmission side (i.e., a contents server) were used, and the transfer rate concerning those files was evaluated. As a result, high-speed downloading of data at 2 GB/s (gigabytes per second)—equivalent to downloading at a rate of one DVD’s worth of data in about three seconds—was confirmed. Under the aim of providing a high-speed downloading service, although investigations on using millimeter waves are presently progressing, the effectiveness of using terahertz wireless communication to further increase data-transfer rate was confirmed in this experiment.