National Taiwan University announced their latest invention System on a Chip (SOC) yesterday, the smallest such product at the lowest cost and consuming the least electricity. The NTU research team claims that the transmission speed of the chip is 100 times as fast as WiFi and 350 times as fast as a 3.5G cell phone. Lee indicated that the chip size has been reduced to 0.5 millimeter, one-tenth of that of existing chips, and the cost is less than one-tenth of the traditional communication module and could be further lowered to only US$1. The SOC successfully combines RF Front-End Circuits and an antenna array to reach the highest transmission speed.
The range of this version is about ten meters. Higher power and bigger antennas can get far more range, but would be for a different class of device.
The transmission speed may reach WiFi 100 times, 3.5G handset’s 350 times, the total power will be one fortieth similar type’s of chip, the chip area is one tenth the size of similar chips.
The chip uses the 60GHz frequency band and has reached 5Gigabit per second transmission speed. Total power usage is below 300 milliwatts.
The demonstration was a prototype chip. Future versions will use better antennas.
With 60 GHZ spectrum there is a potential for moving data at over one Gigabit per second (1 Gbit/s) and up to 8 Gbit/s (over ten meter distances for personal area networks). This will allow things like fast video transfer at a kiosk where you will buy a movie for your Mobile Internet Device (MID) or mobile smartphones. 60 GHz has an advantage with seven GHz of unlicensed spectrum bandwidth available from the FCC.
Taiwan’s chip has fully realized the potential of 60GHz communication.
Several companies (e.g. Proxim’s GigaLink) already make commercial 60 GHz back haul systems that can transmit at rates to 1.25 Gb/s at a distance of a mile or so with a parabolic dish in good weather.
As for data rate you need to look at available bandwidth. With 7-GHz bandwidth available at 60 Hz (57 to 64 GHz in the U.S.), you can really get some great data rates (4 to 5 Gb/s to be conservative), and that is using the simpler BPSK and QPSK modulation methods. Obviously even higher rates are possible with multilevel modulation schemes. With QAM in OFDM you can probably get to the 20 Gb/s range.
Let’s take a look at the basic RF range equation (called the Friis equation) that factors in antenna gains, wavelength, and transmit power and an assumed receive power. Using one mW transmit power, antenna gains of one at both receiver and transmitter, and a desired receive power of 10 nW, I get a range of about 5 inches. Not too useful. Bumping up the transmit power, adding gain antennas and making the receiver sensitivity greater should yield a range of multiple meters. Still pretty poor as it severely limits the application. No doubt manufacturers will work to get that range well up—otherwise why bother? The target is probably 10 meters, which is useful. The problem is the range prediction above assumes an unblocked line-of-sight (LOS) signal path. Any practical usage will encounter walls to penetrate and many obstacles that will create horrible multipath conditions. Under such conditions, assume a maximum range of only a few meters. Is that good enough? Maybe.
One final note about the propagation. As it turns out, 60 GHz is at that part of the spectrum where the absorption of the signal by water molecules is at a peak. That’s probably why they made 60 GHz the unlicensed band. The frequencies directly above and below are more useful. What that means is that when it rains or snows signal amplitude will be severely decreased even blocked. That attenuation is in the 10 dB/km to 15 dB/km or about 1.5 dB/100 meters [attenuation is also from oxygen]. Luckily, most applications will probably be of the indoor variety, so we won’t have to worry about that.
The three device types are defined as follows:
1. A type A device offers video streaming and WPAN applications in 10-meter range LOS/NLOS multipath environments. It uses high gain trainable antennas. This device type is considered as the ‘high end’ – high performance device.
2. A second type B Device offers video and data applications over shorter range (1-3 meters) point to point LOS links with non-trainable antennas. It is considered as the ‘economy’ device and trades off range and NLOS performance in favour of low cost implementation and low power consumption.
3. The third type C device is positioned to support data only applications over point to point LOS links at less than 1-meter range with non-trainable antennas and no QoS guaranties. This type is considered as ‘bottom end’ device providing simpler implementation, lowest cost and lowest power consumption.