Tag Archives: AR

Are We Ready for 6G?

Apart from simply being an evolution of the 5G technology, 6G is actually a transformation of cellular technology. Just like 4G introduced us to the mobile Internet, and 5G helped to expand cellular communications beyond the customary cell phones, with 6G the world will be taken to newer heights of mobile communications, beyond the traditional devices and applications for cellular communication.

6G devices operate at sub-terahertz or sub-THz frequencies with wide bandwidths. That means 6G opens up the possibility of transfers of massive amounts of information compared to those under use by 4G and even 5G. Therefore, 6G frequencies and bandwidth will provide applications with immersive holograms with VR or Virtual Reality and AR or Augmented Reality.

However, working at sub-THz frequencies means newer research and understanding of material properties, antennas, and semiconductors, along with newer DSP or Digital Signal Processing technologies. Researchers are working with materials like SiGe or Silicon Germanium and InP or Indium Phosphide to develop highly integrated high-power devices. Many commercial entities, universities, and defense industries have been going ahead with research on using these compound semiconductor technologies for years. Their goal is to improve the upper limits of frequency and performance in areas like linearity and noise. It is essential for the industry to understand the system performance before they can commercialize these materials for use in 6G systems.

As the demand increases for higher data rates, the industry moves towards higher frequencies, because of the higher tranches of bandwidth availability. This has been a continuous trend across all generations of cellular technology. For instance, 5G has expanded into bands between 24 and 71 GHz. 6G research is also likely to take the same path. For instance, commercial systems are already using bands from FR2 or Frequency Range 2. The demand for high data rates is at the root of all this trend-setting.

6G devices working at sub-THz frequencies require generating adequate amounts of power for overcoming higher propagation losses and semiconductor limits. Their antenna design must integrate with both the receiver and the transmitter. The receiver design must offer the lowest possible noise figures. The entire available band must have high-fidelity modulation. Digital signal processing must be high-speed to accommodate high data rates in wide bandwidth swathes.

While focussing on the above aspects, it is also necessary to overcome the physical barriers of material properties while reducing noise in the system. This requires the development of newer technologies that not only work at high frequencies, but also provide digitization, test, and measurements at those frequencies. For instance, handling research at sub-THz systems requires wide bandwidth test instruments.

A 6G working system may require characterization of the channel through which its signals propagate. This is because the sub-THz region for 6G has novel frequency bands for effective communications. Such channel-sounding characterization is necessary to create a mathematical model of the radio channel that can encompass intercity reflectors such as buildings, cars, and people. This helps to design the rest of the transceiver technology. It also includes modulation and encoding schemes for forward error correction and overcoming channel variations.

Mobile Screen Over Your Eyes

It is no longer necessary to hold a mobile with the hands. How? Thanks to AR or Artificial Reality eyeglasses, it is now possible to transfer the screen of the mobile device to the lens of a pair of eyeglasses. Although this technology was around for a while, the glasses were rather cumbersome and bulky.

Now, Trilite Technologies of Vienna, Australia, has a newer approach to AR glasses that make them look and feel just like normal glasses. According to their CEO, Dr. Peter Weigand, so far, there have been three types of light engine technologies.

The first was the LCoS technology. This is a panel-based technology, and it requires optics with illumination. It is necessary to have a nice, homogeneous, and smooth illumination, and a waveguide must carry the input image. This is not a very efficient technique, and it has a number of optical elements, making it bulky.

The other was the MicroLED display technology. This is semiconductor-based and far superior to a reflective display as it emits its own light. However, it is still a challenge to make the display visible in outdoor applications. And, the two-dimensional display does not scale up when moving to higher FOV or Fields of View and higher resolutions.

The third was the Laser beam scanner technology. This has the highest level of miniaturization. Typically, it has an RGB laser module with three separately mounted lasers as the red, blue, and green light sources. Optics follows the laser module to merge the three beams of lasers into a single ray. A set of MEMS mirrors follows, generating the image scans for the eyeglass display. Two mirrors are necessary, one for the X- and the other for the Y-axis.

According to Weigand, the latest generation of these scanners uses a single MEMS mirror that can move in both x and y-direction. This two-dimensional mirror helps to achieve a lighter and smaller product.

Electronics create the image for display by modulating the lasers. Coupling the image to an optical waveguide allows it to be sent to the display. For this, the laser scanner uses relay optics, a rather large optical element. Coupling the laser beam scanner into the input coupler of the waveguide directly, allows the display engine to be made to a small size. The entire arrangement contains the collimating optics, the MEMS mirrors, and the three lasers.

Trilite Technologies is able to make very small scanners because of its design philosophy. They have designed their scanner such that software rather than hardware handles many of the scanning functions. The other significant contribution to the small size comes from using a single two-axis MEMS mirror rather than one mirror for each axis.

The waveguide contains the optical input coupler as an integral part. This coupler has a pattern of microstructure gratings on its surface, allowing light to enter. The output side, where the light emerges from the waveguide, also has a similar structure. The waveguide conveys the image to the lens and, at the same time, combines the incoming with the generated digital light, allowing the user to see both the digital image and the real-world scene through the eyeglass lens.