Current Issue : April - June Volume : 2021 Issue Number : 2 Articles : 5 Articles
Massive multiple-input multiple-output (MIMO) systems operating at millimeter-wave (mmWave) frequencies promise to satisfy the demand for higher data rates in mobile communication networks. A practical challenge that arises is the calibration in amplitude and phase of these massive MIMO systems, as the antenna elements are too densely packed to provide a separate calibration branch for measuring them independently. Over-the-air (OTA) calibration methods are viable solutions to this problem. In contrast to previous works, the here presented OTA calibration method is investigated and optimized for subarraybased hybrid beamforming (SBHB) systems. SBHB systems represent an efficient architectural solution to realize massive MIMO systems. Moreover, based on OTA scattering parameter measurements, the ambiguities of the phase shifters are exploited and two criteria to optimize the beam pattern are formulated. Finally, the optimization criteria are examined in measurements utilizing a novel SBHB receiver system operating at 27.8 GHz....
To meet the drastic growth of mobile traffic, next-generation wireless networks integrate existing technologies such as dualconnectivity (DC) and network-assisted device-to-device (D2D) communications. In this paper, we present a new spectrum allocation scheme for a heterogeneous system, which incorporates both technologies. For the effective collaboration of individual network agents, we employ the ideas of cooperative games, and the spectrum allocation algorithm is implemented as a novel jointbargaining process. Based on the bargaining solutions of classical Nash, weighted Nash, and Nash bargaining with coalition structure, our three-step interactive approach can leverage the full synergy of different bargaining concepts. Under the dynamic changing HetNet environments, we can take various benefits in a rational way while handling comprehensively the DC-based D2D communication issue and reach an agreement that gives mutual advantage. The main novelty of our proposed scheme is to ensure a relevant tradeoff between conflicting requirements during HetNet operations. Finally, we conduct extensive simulation study and illustrate that the proposed scheme provides a considerable performance improvement by comparison with the existing protocols....
Communicating mobile security threats and best practices has become a central objective due to the ongoing discovery of new vulnerabilities of mobile devices. To cope with this overarching issue, the goal of this paper is to identify and analyze existing threats and best practices in the domain of mobile security. To this extent, we conducted a literature review based on a set of keywords. The obtained results concern recognizable threats and established best practices in the domain of mobile security. Afterwards, this outcome was put forward for consideration by mobile application users (n = 167) via a survey instrument. To this end, the results show high awareness of the threats and their countermeasures in the domain of mobile applications. While recognizing the risks associated with physical and social factors, the majority of respondents declared the use of built-in methods to mitigate the negative impact of malicious software and social-engineering scams. The study results contribute to the theory on mobile security through the identification and exploration of a variety of issues, regarding both threats and best practices. Besides this, this bulk of up-to-date knowledge has practical value which reflects in its applicability at both the individual and enterprise level. Moreover, at this point, we argue that understanding the factors affecting users’ intentions and motivations to accept and use particular technologies is crucial to leverage the security of mobile applications. Therefore, future work will cover identifying and modeling users’ perceptions of the security and usability of mobile applications.Communicating mobile security threats and best practices has become a central objective due to the ongoing discovery of new vulnerabilities of mobile devices. To cope with this overarching issue, the goal of this paper is to identify and analyze existing threats and best practices in the domain of mobile security. To this extent, we conducted a literature review based on a set of keywords. The obtained results concern recognizable threats and established best practices in the domain of mobile security. Afterwards, this outcome was put forward for consideration by mobile application users (n 167) via a survey instrument. To this end, the results show high awareness of the threats and their countermeasures in the domain of mobile applications. While recognizing the risks associated with physical and social factors, the majority of respondents declared the use of built-in methods to mitigate the negative impact of malicious software and social-engineering scams. The study results contribute to the theory on mobile security through the identification and exploration of a variety of issues, regarding both threats and best practices. Besides this, this bulk of up-to-date knowledge has practical value which reflects in its applicability at both the individual and enterprise level. Moreover, at this point, we argue that understanding the factors affecting users’ intentions and motivations to accept and use particular technologies is crucial to leverage the security of mobile applications. Therefore, future work will cover identifying and modeling users’ perceptions of the security and usability of mobile applications....
This paper presents a high-throughput wireless access framework for future 6G networks. This framework, known as K-User MIMO, facilitates all-to-all communication between K access points and K mobile devices. For such a network, we illustrate the demodulation of K2 independent data streams through a new interference cancellation beamforming algorithm that improves spectral efficiency compared to massive MIMO. The paper derives a multi-user Shannon Capacity formula for K-User MIMO when K is greater than or equal to 3. We define an Orthogonal Frequency Division Multiplexing (OFDM) frame structure that demonstrates the allocation of time-frequency resources to pilot signals for channel estimation. The capacity formula is then refined to include realistic pilot overheads. We determine a practical upper-bound for MIMO array sizes that balances estimation overhead and throughput. Lastly, simulation results show the practical capacity in small cell geometries under Rayleigh Fading conditions, with both perfect and realistic channel estimation....
With the rapid development of sensor technology for automated driving applications, the fusion, analysis, and application of multimodal data have become the main focus of different scenarios, especially in the development of mobile edge computing technology that provides more efficient algorithms for realizing the various application scenarios. In the present paper, the vehicle status and operation data were acquired by vehicle-borne and roadside units of electronic registration identification of motor vehicles. In addition, a motion model and an identification system for the single-vehicle lane-change process were established by mobile edge computing and self-organizing feature mapping. Two scenarios were modeled and tested: lane change with no vehicles in the target lane and lane change with vehicles in the target lane. It was found that the proposed method successfully identified the stochastic parameters in the process of driving trajectory simulation, and the standard deviation between simulation and the measured results obeyed a normal distribution.Theproposed methods can provide significant practical information for improving the data processing efficiency in automated driving applications, for solving single-vehicle lane-change applications, and for promoting the formation of a closed loop from sensing to service....
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