High-altitude balloons (HABs) are commonly used for atmospheric research. In recent years, newly developed platforms and instruments allow to measure position, temperature, radiation, humidity and gas profile in the troposphere and stratosphere. However, current platforms, such as radiosonde, have limited bandwidth and relatively small number of possible sensors on board. Furthermore, all the measuring instruments carried on board the balloon cannot be reused since most of the times the radiosonde cannot be retrieved. In this chapter, we present a generic near-space research platform based on an improved radio frequency (RF) communication, an advanced set of sensors that might also include a return-to-home (RTH) micro-UAV. We present the overall structure of an advanced HAB payload, which is equipped with a low-cost sophisticated set of sensors along with HD camera system, which weight less than 300 g. The payload is tied to a weather balloon with a smart autonomous release mechanism and two-way RF telemetry channel (LoRa or Iridium communication). The payload can be released from the balloon at any given time or position, allowing it to fall at a predicted area. In case the payload is attached to a micro UAV, it can return autonomously by multioptional smart decline to a pre-defined location using a built-in autopilot. The suggested new strategy is presented using several case studies and field experiments.

Real-time voice and video streaming applications require a certain Quality of Service (QoS) level for providing user satisfaction. As Wireless Local Area Networks (WLAN's) are not designed for such applications, assessing the communication's QoS level is a challenging task. Sudden Onset Disasters (SODs) poses even a greater challenge as the QoS level must be assessed without generating traffic or consuming any other network resources that the response forces needs for communicating among themselves. As such, passive measurement is the only viable approach, but it lacks suitable metrics for doing so. In this paper, we briefly review the main QoS parameters and later, we propose two new possible measurements. These measures are an extension of the retry-ratio measurements such as the Frame Retry Ratio (FRR) which reflects the effort-efficiency to communicate through the ratio of the extra effort (retries) to the overall effort. Data Retry-Ratio (DRR) is the ratio of extra data transmitted to the overall transmitted data in a period of time. Airtime Retry-Ratio (ARR) is the ratio of the extra airtime cost to the overall used airtime cost. For exploring the performances of these measures, we have developed and designed a special portable testbed which among other things includes a stratum-1 NTP time server. We used this testbed to explore the relations between active measurements: such as one-way delay, throughput and jitter to passive measurements: one-way throughput, one-way FRR, DDR and ARR. The results of a large field-test reveal that passive measurements can reflect the QoS parameters such as the average throughput and can indicate an asymmetric link similar to one-way delay.

As communication is the most fundamental resource for a smart city, it cannot allow any disruption with the related services. Therefore, real-time monitoring systems for the QoS state for the communication infrastructure are vital. Such systems that can detect communications failure can be used also for redeploying emergency and ad-hoc communications infrastructures. Sudden-Onset Disasters (SOD) typically generate system-wide infrastructure breakdowns, including communication. Robust, and efficient communication between the first-responders is crucial for the relief efforts to succeed. Deploying a modern and advanced emergency communication infrastructure requires complicated online-mechanisms and raises several technical challenges. Recent major sudden-onset disasters such as the Fukushima nuclear accident in 2011, the Haiti earthquake in 2010 and the flood in New Orleans in 2005, demonstrated the need to improve the existing technology and make it accessible for rapid deployment on a large scale by non-technical personnel. In this paper, we present a communication infrastructure deployment model suited for the first responders' activity at the scene of a sudden-onset disaster. The model relies on a real-time QoS state monitoring system for reliably predicting communication loss by leveraging the retransmission rate of the users as a link state predictor. This online mechanism can be pre-implemented in the smart city communication infrastructure for day-to-day use and in an SOD scenario as a communication redeployment tool that helps the first-response concentrate their efforts on lifesaving actions. The conceptual model was implemented and tested successfully using 802.11 technology thus demonstrating that it can be effectively used as smart city communication solution.

Objective: We conducted an exploratory investigation of whether grip force could be an indicator of stress in aviation.Background: Pilots might experience stress when anticipating failure to meet task demands and therefore, higher levels of stress can be used as a trigger for engaging automatic assistance. An unobtrusive measure of stress in aviation might be the grip force pilots exert on the control stick that could increase due to the intensified muscle tonus that characterizes psychological stress.Method: Participants were randomly assigned to either an experimental or a control group and performed tracking tasks. Participants in the experimental group were told that as of the second half of the experiment their compensation for the experiment would partly depend on their performance. No such conditioning existed for the control group. Grip force was then measured using a sensor on the control stick.Results: Grip force significantly increased in the second half of the experiment in the experimental group, but decreased in the control group. Similar interaction between experimental group and experimental half was also evident with self-reported stress and galvanic skin response (GSR), yet increases within the experimental group were not significant. Grip force also moderately correlated with GSR, possibly suggesting that they responded to the same construct.Conclusion: Findings provided a preliminary indication that grip force could be used to measure stress in aviation, meriting further research exploration.

Mobile Ad-Hoc Networks (MANET) are known for their rapid deployment and self-organizing capabilities. Those qualities are making MANET a candidate communication infrastructure for rescue forces in emergency events. However, existing Wi-Fi MANET implementations are exhibiting unsatisfactory performance, and the dynamic multi-hop topology of the network makes it difficult to identify the bottlenecks. This paper1 suggests a performance monitoring model for Wi-Fi MANET, incorporating concepts of a Geographic Information and Monitoring System (GIMS), that passively monitors the MANET deployment, thus enabling to optimize and fine-tune the network. Specifically, our monitoring model addresses the known Wi-Fi problems of hidden node and exposed node that are intensified in MANET. We provide a theoretical solution, deriving from the field of conflict graphs, which assists to identify and locate such situations. Experimental results from a real-life testbed that emulates such problems confirm that the suggested approach can effectively detects cases of hidden and exposed nodes in MANET.

Broadcast scenarios, such as streaming HD video to one or many clients, seem as a natural fit for the wireless medium, and indeed the two couple well in satellite TV networks. The same kind of compatibility with broadcast may be expected from modern Wi-Fi networks featuring extended-range Access Points (APs). Yet, the 802.11 protocol was not designed with video broadcast in mind, and therefore lacks crucial broadcast mechanisms, most notably, dynamic rate-adaptation and efficient Forward Error Correction (FEC). For satisfactory Quality of Experience (QoE), it is important that the video stream reaches its destination in time and with a minimal amount of errors. Therefore, in live broadcast, retransmissions should generally be avoided, a goal that can only be accomplished using a reliable feedback mechanism that informs transmitters of current packet loss rates. In this paper we present a live video transmission model for Wi-Fi MANET networks that dynamically adapts the streams' FEC overhead, by utilizing the fact that in Wi-Fi MANET all nodes are periodically broadcasting beacon frames. By overloading these beacons with packet loss-rate information, the transmitting nodes are able to adapt the rate of FEC-encoded redundant packets, the transmission rate and the modulation scheme, without relying on Wi-Fi ACK frames that are costly and inadequate for broadcast scenarios. Moreover, using beacon frames that are part of the 802.11 standard eliminates the overhead associated with proprietary feedback packets in alternative models of broadcast over Wi-Fi. Thus, our suggested scheme enables Wi-Fi MANET networks to reliably transmit live video over multiple hops. Using NS-3 simulations we validate that our FEC adaptation model is applicative and efficient over one hop. Thereafter, we demonstrate via theoretical analysis the tolerable delay associated with the transmission of video over multiple hops using a pipeline model.

Monitoring and analyzing wireless networks for network structure and behavior is a complex task. Such monitoring often requires creating extra traffic, dedicated hardware and a prior knowledge of the network components and structure. In this paper we present a novel approach for monitoring large and complex wireless networks, fast deployed which operate seamlessly and in real time. The suggested framework uses few passive sniffers in order to sample the WiFi communication in the "air" per packet and have an extended cover range due to overhearing abilities. This monitoring system requires no prior knowledge of the network structure. We have designed, implemented and deployed such a passive monitoring system and used it to monitor the campus WLAN network (Wi-Fi). Experimental results show that the suggested framework is highly applicable for unmanaged and partly managed wireless networks such as Ad-hoc, first responders, self deployed and any highly dynamic network.

The mounting evidence, that cellular radiation may adversely affect the health of its users, results in growing concern among the general public. This concern only grows as cellular technologies become an essential part of modern life (mobile e-mail, social networking, etc.). Radiating antennas in the proximity of the user, such as antennas of mobile phones are of special interest for this matter. In this paper we study the performance of a recently proposed architecture for wireless networks, aiming at minimal emission from mobile stations, without any additional radiation sources. The new architecture, dubbed Green Cellular, abandons the classical transceiver base station design and suggests the augmentation of transceiver base stations with receive only devices. These devices, dubbed Green Antennas, are not aiming at coverage extension but rather at minimizing the emission from mobile stations. We employ indoor and outdoor propagation simulation tools and field experiments to study the expected impact of the Green Cellular architecture on emission from mobile stations. Our results reveal a significant, up to 50dB, decrease in emission power and respective exposure to radiation.