Holographic Radio Architecture and Signal Processing in the sub-THz Band for 6G Communications

Driven by new emerging applications such as augmented reality, virtual reality, backhauling, and broadband access, the future wireless connectivity landscape of 6G and beyond will support a wide a range of applications with very-high-throughput requirements. Such stringent requirements make the radio access design very challenging. The traditional approaches to increase the wireless data rate are increasing the bandwidth and multi-input, multi-output (MIMO) techniques. The former is not scalable beyond a few GHz of bandwidth and the latter is often impossible in the sub-THz bands that do not feature rich multipath, which is needed to have a significant channel rank.

A completely different approach, yet largely unexplored, is to resort to MIMO near-field communications, dubbed as holographic radio. The near-field propagation can hold up to a significant range in sub-THz bands, e.g., 10 m links thanks to the very small wavelength. Because transmission in the near field implies spherical waves instead of plane waves, the channel matrix can have a high rank even for point-to-point links. Hence, high throughput can be achieved with moderate bandwidth even in a point-to-point link because multiple independent streams can be sent in parallel.

Your mission for this PhD will be to define a performant - yet realistic - system concept and architecture of MIMO near-field communications and to develop the associated physical layer algorithms, leveraging the specific structure of the channel. You will have to deal with multi-dimensional trade-offs encompassing large antenna count, complexity, theoretical bounds, hardware impairments, to name a few. To support this research, you will develop a detailed simulation environment in Matlab and/or Python. It will be used to evaluate the system performance and optimize the different building blocks of the system. Importantly, it will need a specific channel model for the near-field propagation. The way the near-field channel compares to other MIMO schemes (traditional MIMO exploiting channel diversity, LOS-MIMO, ...) will strengthen the theoretical foundations of this communication scheme. This research may also include experimentation and measurements on a communication testbed.