Robust and scalable signal processing for sub-THz Cell-free MIMO for 6G wireless communication systems

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 and some fundamental performance / complexity tradeoffs must be made. The move to sub-THz bands (100-300 GHz) to approach wireline speeds of 100 Gbps and above requires revisiting the radio access design beyond the state of the art wireless technologies such as 5G networks and WLAN standards (802.11ax/ay).

Building robust THz wireless systems relying mostly on line-of-sight becomes challenging in particular in indoor environments because of shadowing or even blockage. This requires amongst others to distribute the radio access.  Cell-free MIMO that consists of a large number of cooperative distributed access nodes is being considered as one of the main pillars towards reliable and robust radio access in the lower spectrum. However, in the sub-THz bands, the targeted extremely large signal bandwidth will be limited by (i) the fronthaul bandwidth hence limited signal coordination across the access points, (ii) the complexity of the digital baseband signal processing, (iii) the harsh radio propagation channel, including the Doppler shift/spread even with low mobility to name a few. These challenges are by nature different from those in sub-7 GHz, hence motivates the design of a novel distributed radio access.

The PhD candidate will investigate distributed scalable network architectures and PHY/MAC signal processing. The underlying complexity must comply with boundary conditions imposed by HW technology and the FH capabilities resulting in NP-hard multidimensional designs. The research will include topics such as modulation and coding, beamforming and pre- and post equalizers, power control, scheduling, centralized vs distributed processing. The end-goal will be to simplify the overall end-2-end processing across the distributed access points. The proposed designs are expected to achieve (i) higher robustness to Doppler, RF and fronthaul hardware impairments and limitations, (ii) low-complexity synchronization, channel sounding and beamforming algorithms, and (iii) good energy efficiency. The researcher will use model-based approaches as well as machine learning techniques to solve the complex, non-linear design problems.

The successful PhD candidate will build on IMEC's experience in high-throughput mm-wave communication systems to develop his solutions. The research will heavily rely on a detailed simulation environment in Matlab and/or Python to evaluate the system performance and optimize the different components. This research will also include experimentation and measurements on communication testbeds.

As a PhD student, you will be part of a large IMEC team working on the research, implementation and prototyping of sub-THz communications systems composed by experts in digital, analog and mm-wave design, wireless communication systems, signal processing 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.