III-Vs Review

NEC Corporation has successfully developed a highly compact 60GHz band wireless transceiver that transmits uncompressed high-definition television
(HDTV) signals allowing HDTV sets and displays without cable connections.

The features of the wireless video transmission equipment are as follows: the transceiver is adapted to input/output high-quality component video signals. Both uncompressed HDTV signals and stereo audio signals are transformed into a 1Gbps digital-data stream, and then converted to 60-GHz-band to allow wireless transmission by using ASK modulation.

Due to a downsized wireless module and a simplified power supply circuit, a transceiver as small in size as a business card is achieved. Its dimensions are 70x50x 15mm. High-frequency components, such as monolithic IC's, filters and oscillators, are all built into a ceramic module using flip-chip bonding which enables easy assembling with less tuning, as well as a reduction in size.

A path diversity scheme is introduced in the equipment in order to reduce the chance of link-disconnection problems associated with indoor use. A dual receiver configuration enabling two transmission paths ensures continuous transmission as automatic switching from one path to another occurs when an obstacle disturbs the link.

Along with an increase in the prevalence of HDTV broadcasting service in recent years the popularity of wide, flat panel displays, such as plasma and liquid crystals displays has also been increasing.

The installation of these displays requires the use of many cables for video and audio signal connection. This has evoked a strong market demand for a wireless scheme for wall-mounted displays, as well as mobile ones, from the point of view of convenience and appearance.

To date wireless HDTV signal transmission based on wireless LAN at 2.4 and 5GHz or UWB has been developed. However, these warrant special care to prevent interference from other wireless equipment using the same frequency band and require complicated data compression techniques with various standards depending on the application.

A 60-GHz band is well suited for high-speed wireless transmission with a bit-rate of more than 1 Gbps as it has an extremely wide bandwidth of 2.5 GHz, achieves less significant interference at high frequencies, and requires no license if technical regulations are fulfilled.

The technology does not simply allow discrete wireless equipment, but can also be extended to various high-data-rate wireless applications involved in wireless personal area networks.