Japanese telco NTT has built a prototype of what it calls the world's smallest full-coverage 60GHz wireless networking module. Able to operate on four 2.16GHz-wide channels between 57 and 66 GHz with each channel capable of supporting 3.8Gbps, the aggregated speed can reach 15Gbps — a DVD in under ten seconds.
Image credit: NTT
60GHz is the newest unlicensed band available worldwide, albeit with some national differences: at 57.1 - 63.9 GHz, for example, the UK's allocation is slightly smaller than that of the Japanese.
60GHz is seven times wider than all other wireless data bands combined. Image credit: NTT
At such a high frequency, much of the signal is quickly absorbed by the atmosphere, meaning that very high gain antennas are needed and that transmitters and receivers must be close to each other. However, it also means that multiple high speed 60GHz services can exist in the same area without mutual interference — so that in-building data transfer systems like this and in-vehicle 60 GHz radar and communications systems can share the band safely.
Image credit: NTT
The NTT transceivers are about the size of a postage stamp and are built on a low temperature co-fired ceramic (LTCC) base, which has all of the components baked into a multi-layer ceramic substrate. A pattern of stacked conductive rings within multiple layers of the LTCC form a dish-like reflector for the radio signals, making the device its own antenna. Varying the size and placement of the various reflective conductors gave the designers a lot of flexibility in determining gain and bandwidth.
The test signal worked across a three centimetre air gap. Image credit: NTT
NTT made the announcement on Monday last week. Currently, NTT is testing separate receiver and transmitter devices, although creating a transceiver, where one device does both jobs, is entirely possible. As such systems will be used only occasionally, to transfer large amounts of data in very short bursts, they shouldn't have much impact on battery life in portable devices. NTT envisages the technology will find a home in kiosks selling high-definition content.