As the throughput requirements for wireless communication links keep rising, characterization of sub-THz radio channels is necessary. This paper presents the results of a radio channel measurement campaign in which we characterize the full D-band, ranging from 110 to 170 GHz, for distances up to 5 m. We measured penetration and reflection loss for a broad set of materials that are commonly used in indoor environments, including wood, glass, acrylic and concrete, and measured corner diffraction losses. Measurements over the full 60 GHz bandwidth reveal frequency selectivity as well as a periodic variation of both penetration and reflection loss, which is attributed to the thin film effect. Based on measurements in a conference room and outdoors, we create a spatio-temporal channel model for the conference room and an outdoor path loss model. The channel models show that the radio channel is extremely sparse with respect to multipath components, containing only a Line-of-Sight path with signal attenuation close to path loss in free space, and first-order reflections with a measured attenuation that corresponds to the sum of the path and reflection loss.

This paper presents the analysis of a channel sounding campaign in the hull of a bulk carrier vessel at sub-6 GHz frequencies 868 MHz, 2.4 GHz and 5.25 GHz as well as mmWave frequency 60.48 GHz. For the sub-6 GHz frequencies, path loss (PL) is measured using omnidirectional antennas. The measured PL is fitted to a one-slope PL model that takes into account attenuation due to engine room floor crossings, obstructions and walls. The fitted model has a reference PL lower than free space and a PL exponent around 1.2. For mmWave wireless communication high gain directive antennas are typically used. Therefore, the directive radio channel for Line-of-Sight (LOS) communication is measured using the Terragraph channel sounder and an antenna beam width dependent PL model is created. At mmWave frequencies, LOS PL in the vessel is close to PL in a free space environment, but angular spread values are lower than in other indoor scenarios.

With the potential of fixed wireless access networks as an alternative to optical fiber, it is necessary to determine vegetation loss at millimeter wave frequencies. In this paper, we present vegetation loss measurement results for different types of vegetation, including trees, hedges, and forests, at frequencies ranging from 110 GHz to 170 GHz. An experimental method is proposed to determine the average loss per meter vegetation depth for different vegetation types. Average losses at 140 GHz range from 0.2 dB/m for an open forest, and up to 9.8 dB/m for dense hedges. As there is a large variance of vegetation loss for different vegetation types, we propose a novel vegetation-dependent exponential decay (VED) model, expressing vegetation loss as a function of vegetation depth, frequency, and vegetation density, which is expressed by the plant area index (PAI) parameter. The VED vegetation loss model can be used for network design, and to perform accurate link budget calculations.

Fixed wireless access networks at millimeter wave frequencies enable an alternative to fiber-optic installations for providing high-throughput internet connectivity. In this letter, we present outdoor channel measurements at D-band frequencies ranging from 120 GHz to 165 GHz, contributing to the design of future fixed wireless access networks. We measure angular path loss (PL) for both Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) scenarios and calculate angular spread. We also measure building reflection loss for different angles and building facades. Directional LOS PL equals free-space PL, whereas omnidirectional PL is slightly lower. The angular spread of the LOS measurements is 19.7∘. The omnidirectional NLOS PL model has a higher PL and the angular spread increases to 54.4∘. Losses up to 11 dB should be taken into account for reflection on a fiber cement or building brick facade. and up to 15.6 dB and 18.5 dB for roughcast and stone bricks. Even though wireless communication via the direct path is preferred, reflected paths can enable high-throughput wireless communication if the direct path is obstructed.

With the deployment of data-driven assembly and production factories, challenges arise in sensor data acquisition and gathering. Different wireless technologies are currently used for transferring data, each with different advantages and constraints. In this paper, we present a hybrid network architecture for providing Quality of Service (QoS) in an industrial environment where guaranteed minimal data rates and maximal latency are of utmost importance for controlling devices and processes. The location of the access points (APs) is determined during the initial network-planning action, together with physical parameters such as frequency, transmit power, and modulation and coding schemes. Instead of performing network-planning just once before the network rollout, the network is monitored continuously by adding telemetry data to the frame header of all data streams, and the network is automatically reconfigured in real-time if the requirements are not met. By not using maximum transmit powers during the initial roll-out, more APs are needed, but coverage is guaranteed when new obstructions such as metallic racks or machinery are added. It is found that decreasing the transmit power by 6 dB gives the best trade-off between the number of required APs and network robustness. The proposed architecture is validated via simulations and via a proof-of-concept setup.