Radio signal propagation modeling plays an important role in designing wireless communication systems. The propagation models are used to calculate the number and position of base stations and predict the radio coverage. Different models have been developed to predict radio propagation behavior for wireless communication systems in different operating environments. In this paper we shall limit our discussion to the latest achievements in radio propagation modeling related to tunnels. The main modeling approaches used for propagation in tunnels are reviewed, namely, numerical methods for solving Maxwell equations, waveguide or modal approach, ray tracing based methods and two-slope path loss modeling. They are discussed in terms of modeling complexity and required information on the environment including tunnel geometry and electric as well as magnetic properties of walls.

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Fast deployable and reliable mission-critical communication networks are fundamental requirements to guarantee the successful operations of public safety officers during disaster recovery and crisis management preparedness. The ABSOLUTE project focused on designing, prototyping and demonstrating a high-capacity IP mobile data network with low latency and large coverage suitable for many forms of multimedia delivery including public safety scenarios. The ABSOLUTE project combines aerial, terrestrial and satellites communication networks for providing an robust standalone system able to delivering resilience communication systems. This article focuses on describing the main outcomes of the ABSOLUTE project in terms of network and system architecture, regulations and implementation of the Aerial Base Stations, Portable Land Mobile Units, Satellite Backhauling, S-MIM Satellite Messaging and Multimode User Equipment.

Optical Wireless link provides high bandwidth solution to the last mile access bottleneck. However, an appreciable high availability of the link is the basic requirement of any communication application. Free Space Optics (FSO) links are highly weather dependent and fog is the major attenuating factor reducing the link availability. Hybrid networks consisting of Free Space Optics (FSO) link and back up link in the GHz frequency range renders high availability besides providing comparable data rates. The back up link should be nearly immune to fog attenuation for achieving carrier class availability. In this paper effects of fog on FSO and GHz frequency range links are studied so that frequencies with best complementary behaviour can be selected as a back up link.

This work discusses a novel approach to image acquisition which improves the robustness of captured data required for 3D range measurements. By applying a pseudo-random code modulation to sequential acquisition of projected patterns the impact of environmental factors such as ambient light and mutual interference is significantly reduced. The proposed concept has been proven with an experimental range sensor based on the laser triangulation principle. The proposed design can potentially enhance the use of this principle to a variety of outdoor applications, such as autonomous vehicles, pedestrians' safety, collision avoidance, and many other tasks, where robust real-time distance detection in real world environment is crucial.