Over the last few years, discussions oriented toward defining sixth generation (6G) requirements and possible technologies have started to circulate within the wireless community. One of the key ideas will likely be to take steps to remove the conventional cell boundaries and facilitate enhanced joint uplink and downlink processing using many dispersed access points (APs). These ideas fall within the academic definition of cell-free massive multiple-input multiple-output (CFmMIMO). It alleviates the existing cell-edge and handover problems and improves energy efficiency. The primary limiting factor is achieving cell-free operation in a practically feasible way, with computational complexity and fronthaul requirements that are scalable to large networks with many users. This poses many important research questions that must be explored systematically and in-depth. This project firstly develops scalable artificial intelligence (AI)-based solutions. Together with the appropriate (cost-efficient) AP deployment planning tools (e.g., where to put the APs), these developments constitute a significant step toward enabling the low-latency and uniformly reliable wireless services at a lower cost. Given the international nature of the project, the project contributes to the development of a diverse workforce in AI and 6G wireless networks through the formation of international research teams integrating undergraduate and graduate students.



Project research activities are organized into three thrusts. Thrust 1 develops scalable AI-based resource allocation solutions enabling the implementation of large-scale CFmMIMO. The developed solutions are further enhanced by exploring AI architectures applicable to large networks. This includes the security aspects, especially in the context of AI algorithms and architecture, and the cloud radio access network. Thrust 2 focuses on establishing network planning and waveform constraints to address scalable deployment solutions. This includes the development of infrastructure-aware minimum-cost AP deployment methodologies by taking into account the QoS requirements and available transport infrastructure. The developed methodologies are further augmented by developing a network-wide user signal detection method, accounting for the fronthaul capacity and the quantization resolution at each AP. This task also investigates how CFmMIMO can address many of today’s most challenging spectrum policy issues. Evaluation Thrust evaluates and analyzes the methodologies developed in Thrusts 1&2. This employs the existing US and European experimental testbeds and provides a continuous feedback cycle between theory and experimentation. The US team will build upon the prior experience with Colosseum. On the European side, the team will experiment with the Open Air Interface (OAI).