Millimeter Wave for High Speed Communication

Author: Kenichi Kashima

Hitachi Wireless Broadband Project Group has been involved in a business consists of design, development, manufacture and sales of equipment and systems used in broadcast, image surveillance and wireless communication. Especially in wireless communication the Hitachi products using millimeter and sub-millimeter wavelength have been applied to primarily high speed usage. In the millimeter wavelength 60 GHz bandwidth is mainly used.

HISTORY

In Japan standards and regulations for wireless communications have been revised, in order to utilize ­millimeter wavelength since 2000. Under these new standards and regulations, using 60 GHz bandwidth, wireless mass data transmissions for short distance are made possible at a remarkable speed. Some of applications, using 60 GHz bandwidth, include super-high-speed wireless LAN, wireless image transmission, millimeter wavelength radar, multiple transmissions of TV broadcasting.

ADVANTAGES/DISADVANTAGES

The wave in 60 GHz is not suitable for long distance communications because of increased attenuation by oxygen compared with lower bandwidths. On the other hand, higher utilization of frequencies is achieved as same frequency in 60 GHz bandwidth can be placed repeatedly in a narrow band. Another advantage is that only few interference waves are generated in this bandwidth. The occupied bandwidth per channel as wide as 2.5 GHz makes it most suitable for mass data transmission for short distance. Frequencies are assigned in 54.25~59.0 GHz licensed band and 59.0~66.0 GHz unlicensed band. Two bands can be selected as per different usages.

LATEST DEVELOPMENT

Hitachi has developed wireless transmission devices of 60 GHz bandwidth for mobile access systems and super high-speed wireless LAN systems. They are delivered to railway and telecommunication operators. For broadcasting application a non-compression HDTV (High Density TV) transmission system has been developed and transmission rate of 1500 Mbps has been achieved.

Interfaces of these devices for telecommunications are for 10/100 Base-TX, 1000 Base-SX, and 100 Base-T. Standards for broadcasting are for SD-SDI (standard definition serial digital interface) and HD-SDI (high-definition serial digital interface). Therefore, existing equipment can easily be applied.

Transmission speed is 100~1000 Mbps and it is usable for transmitting large contents and for main highway of wireless telecommunication. This is already used by users like railway-operators, private companies, government, and many local governments who own their own communication networks. It is expected that the high-speed wireless market will grow rapidly.

LATEST DEVELOPMENT

PARTNERSHIP

These wireless transmission devices are designed for outdoor use. Therefore, the reliability of connections and components exposed to outside environment is critically important. They must be dust/waterproof, and mechanically robust for many years in order to ensure reliable electrical connections. Also, reducing connection time at the construction site is considered to be very important.

In order to meet these requirements Hitachi has adopted HARTING RJIndustrial Data 3A connectors with UV protected system cables for wired data communication and HARTING PushPull connector for power supply of the device.

FUTURE PROJECTS

Recently, the demands for systems that combine broadcasting and surveillance images with wireless technology are increasing. Hitachi will develop a new business to meet these demands by integrating experiences and technologies in the fields of broadcasting, surveillance and wireless technologies.

Kenichi Kashima
Wireless Broadband Project Team
Hitachi Kokusai Electric Co., Ltd.
Kenichi Kashima