Communication In Urban Areas Research Articles

Physical-Environment-Map-Aided 3-D Deployment Optimization for UAV-Assisted Integrated Localization and Communication in Urban Areas

Physical-Environment-Map-Aided 3-D Deployment Optimization for UAV-Assisted Integrated Localization and Communication in Urban Areas

Optimization of Full-Duplex UAV Secure Communication with the Aid of RIS

Recently, unmanned aerial vehicles (UAVs) have gained significant popularity and have been extensively utilized in wireless communications. Due to the susceptibility of wireless channels to eavesdropping, interference and other security attacks, UAV communication security faces serious challenges. Therefore, novel solutions need to be investigated for handling corresponding issues. Note that the UAV with full-duplex (FD) mode can actively improve spectral efficiency, and reconfigurable intelligent surface (RIS) can enable the intelligent control of signal reflection for improving transmission quality. Accordingly, the security of UAV communications may be considerably improved by combining the two techniques mentioned above. In this paper, we investigate the performance of secure communication in urban areas, assisted by a FD UAV and an RIS, where the UAV receives sensitive information from the ground users and sends jamming signals to the ground eavesdroppers. Particularly, we propose an approach to jointly optimize the user scheduling, user transmit power, UAV jamming power, RIS phase shift, and UAV trajectory for maximizing the worst-case secrecy rate. However, the non-convexity of the problem makes it difficult to solve. Combining alternating optimization (AO), slack variable techniques, successive convex approximation (SCA), and semi-definite relaxation (SDR), we propose an effective algorithm to obtain a suboptimal solution. According to the simulation results, in contrast to other benchmark schemes, we show that our proposed algorithm can significantly improve the overall secrecy rate.

Scattering Mitigation Frequency Selective Surface for Unidirectional Blockage Compensation

This communication describes a concept of scattering mitigation frequency-selective surface (FSS) for unidirectional blockage compensation using a single substrate FSS without modification of the obstacle. The devised scattering mitigation FSS generates the complementary electric field to that of the blockage, enabling the blockage to become electromagnetically transparent to the antenna. Using superposition and linearity, the spatial impedance distribution of the FSS is calculated. The devised FSS consists of indented patch elements consisting of four symmetric via structures to exhibit a wide tunable transmission phase range and less than 1 dB insertion loss at the center frequency of 30.0 GHz for proof-of-concept. The proposed scattering mitigation FSS is verified in transverse magnetic (TMz)- and transverse electric (TEz)-polarized cylinder scattering scenarios. The measurement confirms the improvements of the main beam peak gain and restoration of far-field radiation patterns. The proposed investigation is expected to provide concise and practical scattering reduction solutions for blockage scenario such as vehicular communication in urban areas.

Predictors Associated with Health-Related Heat Risk Perception of Urban Citizens in Germany.

The rising probability of extremely high temperatures and an increasing number of consecutive hot days caused by climate change—combined with the impact of these high temperatures on human health—is widely discussed in the literature. There are calls for the development of heatwave adaptation measures by governmental and scientific institutions. In this research, the predictors of health-related heat risk perception of urban citizens in Augsburg, Germany, were investigated. An online survey was conducted with 468 citizens, asking about their heat risk perception, knowledge about heat risks, and demographic data and health information. Statistical methods (Spearman correlation, unpaired t-test, ANOVA and multiple regression) were used to determine which factors were significant and relevant. The results show that the knowledge of heat risks, heat risk sensitivity and an external locus of control are the most important factors for heat risk perception. The health implication score and chronic disease show significant effects in descriptive statistics. Furthermore, younger people showed the highest heat risk perception of all age groups. Surprisingly, income, education, living alone and gender did not play a role in heat risk perception. The findings imply a need for better and intensified heat risk communication in urban areas—especially among elderly people—and thus are important for creating acceptance towards heat wave risks, which is a prerequisite of willingness to adapt.

Is spectrum sharing in the radar bands commercially attractive?—a regulatory and business overview

AbstractThe need to meet users' expectations in the ‘mobile data avalanche’ represents a significant challenge for mobile network operators. More spectrum is a natural way to meet these requirements in a cost and time‐efficient way, but new, exclusively licenced spectrum is increasingly hard to come by. Instead, vertical spectrum sharing has been discussed as a potential solution for finding additional spectrum. In this paper, we focus on vertical spectrum sharing in the radar bands for providing short‐range wireless access, for example, indoors and in hotspots that ‘offload’ traffic demand. We propose a methodology for analysing the technical, regulatory and business aspects of deploying large‐scale wireless networks. Then, we identify the following criteria for achieving business success: spectrum availability, availability of low‐cost end‐user devices, system scalability in terms of number of concurrently used devices and finally the ability to guarantee a quality of service for the users. Our technical availability assessment has identified geo‐location database as the necessary technical enabler and detect‐and‐avoid mechanism as an auxiliary enabler for improving sharing conditions. Moreover, licenced shared access was found to be the suitable regulatory framework to support the proposed sharing mechanism and regulatory policies in real‐life implementation. Our business feasibility assessment concludes that there is enough spectrum available for indoor and hotspots communication in urban areas in the radar bands to make a large‐scale system commercially viable. Service quality can be guaranteed, and there is a strong potential to construct low‐cost devices. Uncertainties do, however, remain regarding the spectrum access cost. Copyright © 2015 John Wiley & Sons, Ltd.

Effect of scattering environment on estimation quality in V2I and V2V communications

In this paper, we use a set of modulated discrete prolate spheroidal sequences (MDPSS) to represent a band-limited channel in the scenario with scattering from one or more clusters which can be used in both vehicle-to-infrastructure (V2I) or vehicle-to-vehicle (V2V) communication cases. Then we evaluate the performance of 2×1 space-time transmit diversity (STTD) system with Alamouti coding and imperfect channel estimation at the receiver. We consider examples of different scattering environments which represent vehicular communication in urban areas, derive expressions for autocorrelation function of channel gains and verify it by simulation. Scattering effect on estimation quality of the system is examined in terms of minimum mean square error (MMSE) and bit error rate (BER).

A Study on the Uses of Social Networking Sites on Young Adults to Infer on the Different Types of Users

Social Networking Sites (SNSs) are used for multiple purposes and have become an essential part of our everyday activities. The divergent uses of SNSs make SNSs as an interactive platform for interpersonal connectivity and social enhancement through social communication. The study investigates on the frequently used SNSs and uses of SNSs among the young adults in Bangalore city to infer on the different types of users. The research study used survey method to collect information from 120 young adults (20-35 years) across Bangalore city. The study found that Facebook, LinkedIn, Twitter and Google+ were the frequently used SNSs. The study identified 32 uses of SNSs, from which 30 different types of SNSs’ users were inferred, they are: Networkers, Chatters, Buddy’s Info Seekers, Content Makers, Professors, Hobby Vicars, Reporters, Preachers, Frequent Communicators, Status Stealers, Self-Broadcasters, Philosophers, Pet Lovers, Attractive Posters, Best Wishers, Attention Grabbers, Vernacular Posters, Like Likers, Responders, Silent Observers, Social Stars, Players, Endorsers, Dedicated Followers, Daters, Feature Lovers, Career Seekers, Learners, Political Campaigners and Info Pilfers. The divergent uses of SNSs in the present study reinforce SNSs as the preferred choice of communication tool, especially for social communication in urban areas.

Grid-Based Predictive Geographical Routing for Inter-Vehicle Communication in Urban Areas

Vehicular ad-hoc networks (VANETs) are highly mobile wireless ad hoc networks for vehicular safety and other commercial applications, whereby vehicles move non-randomly along roads while exchanging information with other vehicles and roadside infrastructures. Inter-vehicle communication (IVC) is achieved wirelessly using multihop communication, without access to fixed infrastructure. Rapid movement and frequent topology changes cause repeated link breakages, increasing the packet loss rate. Geographical routing protocols are suitable for VANETs. However, they select the node nearest to the destination node as a relay node within the transmission range, increasing the possibility of a local maximum and link loss because of high mobility and urban road characteristics. We propose a grid-based predictive geographical routing (GPGR) protocol, which overcomes these problems. GPGR uses map data to generate a road grid and to predict the moving position during the relay node selection process. GPGR divides roads into two-dimensional road grids and considers every possible node movement. By restricting the position prediction in the road grid sequence, GPGR can predict the next position of nodes and select the optimal relay node. Simulation results using ns-2 demonstrated performance improvements in terms of local maximum probability, packet delivery rate, and link breakage rate.