Page 290 - ITU-T Focus Group IMT-2020 Deliverables

4 ITU-T Focus Group IMT-2020 Deliverables

A high-gain slot-array antenna (using approximately 1000 elements in experiments) that enabled spatial
isolation was developed by Tokyo Tech (at Ando-Hirokawa Labs). In addition, the radio waves do not spread
out and are confined for more than 10 m in a cylindrical service area.
In the scenario where users pass through the communication area within a short period of time, Sony has
also implemented a MAC protocol on the RF-BB LSIs, enabling reduced link-setup times that allow users to
start communications within 2 ms or less. JRC has integrated these technologies to form the GATE system.

Figure 25 – Photographs of the 60 GHz GATE wireless system
To locate the service area for the 60 GHz GATE system, which is a small portable access point, in arbitrary
positions in the large zone as quickly as possible, easy installation-type radio link systems to accommodate
GATEs are advantageous.
We performed a successful field demonstration of an example configuration that allowed a combined
operation of the 60 GHz band GATE system and the 40 GHz band wireless access system with the maximum
link length of 1 km or more with 1 Gbps-class speed.

In the 40 GHz band wireless access system used here, the directional division duplex (DDD) system was
adopted to perform simultaneous two-way communication on the same frequency and the same polarized
wave, rather than the conventional frequency division duplex (FDD) or time division duplex (TDD) methods;
DDD doubled the frequency utilization efficiency in principle.
The realization of DDD was only enabled by full use of high-isolation between transmitting and receiving
antennas arranged in parallel and cancellation technology of transmitted signal leaked in the circuit.

Figure 26 – Photographs of the 40 GHz wireless system using DDD

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