NTT Develops 15Gbps Milliwave Transceiver Module

Jan 20, 2012
Tetsuo Nozawa, Nikkei Electronics
The 60GHz waveband transceiver modules placed on the large metal boxes are used to transmit high-definition (HD) video data.
The 60GHz waveband transceiver modules placed on the large metal boxes are used to transmit high-definition (HD) video data.
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The transceiver module and antenna
The transceiver module and antenna
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A 12 x 12mm board for the "pseudo-reflection mirror-surface antenna"
A 12 x 12mm board for the "pseudo-reflection mirror-surface antenna"
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Wireless devices that are expected to be equipped with the transceiver module once the size of the module becomes equivalent to that of the antenna
Wireless devices that are expected to be equipped with the transceiver module once the size of the module becomes equivalent to that of the antenna
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Nippon Telegraph and Telephone (NTT) Corp developed a compact wireless transceiver module supporting all of the four communication channels that can be used in the 60GHz waveband.

The transmission range of the module is about 50cm. The maximum data transmission speed of each channel is 3.8Gbps (15Gbps when all of the four channels are used at the same time).

Technically, the module can be embedded in tablet computers and smartphones. Therefore, it is possible to download a large volume of data such as a movie to a smartphone in several to several tens of seconds just by placing the phone near a kiosk terminal.

High-speed version of TransferJet?

There has already been a wireless communication standard that enables to exchange data just by holding a smartphone, etc near a home appliance and so forth. It is Sony Corp's "TransferJet" short-range wireless standard, which is being employed for mobile machines. However, its maximum data transmission speed is 560Mbps.

"(With TransferJet,) it takes several minutes or more to transmit data stored in a Blu-ray disc," NTT said.

In a sense, the new wireless transceiver module was developed to drastically improve the data transmission speed of TransferJet.

The module measures 12 x 6 x 3cm.

"We intentionally made a large module to ensure extra space," the company said.

To develop the module, NTT employed an antenna made by using a multilayer LTCC (low temperature co-fired ceramics) board in addition to an MMIC (microwave monolithic integrated circuit) in the physical layer and increased the number of channels from two to four.

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The size of the antenna is as small as 12 x 12mm.

"The sides of many antennas used for existing products measure several centimeters," the company said. "That means we reduced area by 90% or more."

As an antenna, NTT used the "pseudo-reflection mirror-surface antenna," which it has been developing since about 2006 (See related article). Though the size, etc of the antenna has not been changed since 2009, the company newly added a passive device in the center of the antenna so that it supports the four channels.

NTT realized the capability of using the four channels by expanding the bandwidth supported by the 90° phase shifter used for the sub-harmonic mixer circuit in the transceiver circuit. Before that, the bandwidth of the phase shifter was narrow. And if it was used for the four channels, it would be difficult to ensure the data transmission speed of 3.8Gbps for each channel, the company said.

The development of the wireless transceiver module is now beyond the research phase and in the phase of commercialization. Technically, the size of the entire module can be reduced so that it becomes equivalent to the size of 12 x 12mm antenna board, NTT said.

"We want to embed the module in a tablet computer and demonstrate it in a simple way within three years," it said.

NTT to develop its own specification by combining existing ones

There are several wireless communication standards for the 60GHz bandwidth such as WiGig (Wireless Gigabit Alliance), WirelessHD, IEEE802.11ad and IEEE802.15.3c. Though they are currently being commercialized except for IEEE802.15.3c, NTT is not planning to employ an existing standard as it is.

"We will develop our own specification based on IEEE802.11ad while combining IEEE802.15.3c and other standards," it said.