The Internet of Things (IoT) has the potential to solve major global challenges, but current reliance on primary batteries for wireless sensors creates significant environmental and economic costs. The Horizon Europe AMBIENT-6G project addresses this by developing energy-neutral devices (ENDs) that harvest power from ambient sources, enabling decades-long, maintenance-free operation. 
A central task of the AMBIENT-6G project is to investigate how future 6G network infrastructures must adapt to enable ultra-low-power communication and seamlessly integrate these devices, particularly during the critical initial access phase. The initial access phase is the first wireless transmission between an access point (AP) and a device. 
It is particularly challenging for passive ENDs, which transmit data through backscatter communication and therefore rely on a supply of RF power through the AP to wake up. This thesis project will address the initial access problem for a distributed, multi-antenna infrastructure of APs. Through beamforming, multi-antenna APs have the potential to achieve large communication distances to ENDs. But the downside is the difficulty to initially find the ENDs that may be present. Beamforming strategies are required to focus the RF power to certain positions or in certain directions. There are several candidate strategies to choose from, such as 1) codebook-based, 2) geometry-based, or 3) random beamforming, which trade off complexity (e.g., search space) vs. efficiency. Goal of this work is to analyze these trade-offs based on computer simulations and experimental data.