Flexible transceiver architectures for FR3 and NTN applications

The upper mid-band or FR3 spectrum (approximately 7–24 GHz) is emerging as an important candidate for future wireless systems, combining access to wider bandwidths with more favorable propagation than traditional millimeter-wave frequencies. Exploiting this spectrum efficiently will, however, require large antenna arrays and potentially many RF chains, creating significant challenges in hardware complexity and energy consumption. This band offers a promising trade-off between additional capacity and sufficient coverage, but it also brings many research challenges:

• The FR3 band is not completely available but consists of multiple sub-bands at non-contiguous frequencies. Communicating devices will need to dynamically adapt to those different bands, based on their availability, and potentially use different sub-bands simultaneously. This requires novel transceiver architectures, combining flexibility, high-throughput, reliable communications and low power consumption
• More specifically, large multiple-antenna architecture should dynamically adapt their active hardware to the spatial characteristics of the radio environment, exploiting differences in propagation as function of antenna location and carrier frequency, such that the best power/performance configuration is enabled by adapting or selectively de-activating specific antenna chains.

Simultaneously to the FR3 emergence, thousands of communication satellites are being launched, offering direct user connectivity by complementing the ground base stations with non-terrestrial networks (NTN) to support increasing traffic and serve poorly or unconnected areas. While satellites initially employ lower frequencies below 3 GHz, future generations will progressively consider the FR3 band for increased capacity. This brings specific challenges:

• To support communication over a range of some 500 km, satellites need a much larger and higher-gain antenna array architecture. This opens a large space for transceiver architecture optimization including digital, analog and antenna components.
• Due to their position in orbit, they need to provide an high flexibility supporting current and future applications, as human maintenance intervention will not be possible. They also need advanced beam management solutions designed for their high speed.
• Finally, power consumption is also severely constrained due to solar panel area, battery weight and limits of radiative heat dissipation. This makes the design and optimization of FR3 satellite architectures much more challenging in all aspects and requires disruptive solutions.

As a PhD student, you will seek fundamental understanding and propose novel solutions related to those challenges. You will understand the differences in channel propagation and hardware implementation constraints in NTN context across the FR3 band. You will propose novel transceiver architectures and communication algorithms offering flexibility while optimizing power-performance trade-offs. AI tools may complement model-based design to guide the selection and optimization of a different architectures for each specific use case. The proposed concepts will be implemented and evaluated using experimental FR3 multi-antenna platforms and site-specific channel measurements.

You will be part of a large imec community working on the research, implementation and prototyping of future communications systems with experts in wireless communication, signal processing, digital, analog and mm-wave design, and machine learning. This is a unique opportunity to develop innovative, multi-disciplinary technology and shape future wireless networks. You will publish your research in top-level journals and conferences