How XR glasses are making us rethink antenna design
Not every device connected to the 5G network will be a phone or a tablet. As the 5G era unfolds, a growing number of consumer and industrial devices – from sensors and robots to headsets and wearables – will gain the ability to connect to the mobile network. Each new device, however, comes with its own set of radio frequency (RF) design challenges. As 5G devices evolve, we will need to find new ways of shaping and integrating antennas into these new form factors, while maintaining the same levels of performance, reliability and safety we’ve come to expect from our phones.
Extended reality (XR) glasses exemplify this kind of challenge. At Nokia, we believe XR will be a driving force of the metaverse, and we’re certainly not the only ones. Apple’s recent unveiling of the Vision Pro is just the latest in a growing list of XR-spatial computing devices. But while XR headsets are proliferating today, a critical future step is to make these devices truly mobile. That means shrinking them down in size, and then linking them directly to the 5G network.
Not only must we embed connectivity into these devices, but we must do so in the most subtle ways possible. The mixed reaction to Google Glass has shown that consumers want their smart headgear to be unobtrusive. In short, device makers will need to design connected XR glasses that look just like ordinary glasses.
With that challenge clearly delineated, Nokia set out to solve the problem of creating an optimal radio design for XR glasses. We are publishing the results of that research in white paper, but to summarize, we concluded that to create the ideal RF conditions for a pair of spectacles, we need to place the antennas on either side of the glasses’ rims, directly below the hinges.
Why at the edge of the frames? We found it to be the optimal location for many technical reasons:
- The placement has enough space to place a single slim, polarized 1X4 antenna array, which, if matched with a similar antenna array at the other side of the frames, allows us to achieve 2x2 MIMO connectivity. This delivers the optimal 5G performance without the need for beam steering, which would make antenna design far more complicated in the limited space glasses provide. Using simple high-gain, high-efficiency antenna arrays on XR devices will also lower the required absolute power level of the power amplifier, minimizing heat levels.
- By moving the antennas to the outside edge of the frames, we minimize RF exposure to the head – especially the eyes, which are much more sensitive to RF radiation than the skin.
- The positioning of the antenna means RF propagation is consistently aligned with the plane of the network transmission. Phones must be optimized for any orientation, as they are carried around in pockets and bags and held in numerous different positions. But glasses are worn, which means there is only free movement along one plane (the turning of the head). This allows for the optimization of the antenna in a single dimension, limiting the need for beam steering.
Antenna design isn’t the only challenge we need to overcome in order to create XR glasses that offer a truly seamless experience for users. We will need artificial intelligence technologies that recognize the images we see through these glasses and understand the context in which those images exist. We will need improved sensing and interface technologies that can track eye movements and allow us to interact in mixed-reality environments in new ways. We will need advanced optical technologies that can seamlessly impose the virtual world over the real world. We will need new ultra-energy-efficient processors and power amplifiers that can easily handle the demands of immersive XR while generating less heat, since any device worn on one’s head needs to maintain ambient temperatures at all times.
At Nokia, we enable XR services from an end-to-end perspective including devices, access-agnostic networks, connectivity technologies and standards. Even if standards doen’t make the front pages, they are critical for interoperability thus achieving economies of scale, supporting XR device and application proliferation, and ensuring users' safety, security, and privacy.
5G connectivity will be among those critical elements in the XR device innovation chain, supporting the mobility that ubiquitous XR requires. We are confident that our research into antenna designs will help device makers make 5G connectivity in XR glasses a reality, while keeping them slim, lightweight and comfortable. By optimizing antenna designs specifically for the unique demands of new device form factors, we can create truly useful technology that human beings use in their everyday life.
For more information on Nokia’s groundbreaking standards work, please visit our Standardization page.