查看更多>>摘要：For a smart healthcare system, a cloud based paradigm with numerous user terminals is to support and improve more reliable, convenient, and intelligent services. Considering the resource limitation of terminals and communication overhead in cloud paradigm, we propose a hybrid IoT-Fog-Cloud framework. In this framework, we deploy a geo-distributed fog layer at the edge of networks. The fogs can provide the local storage, sufficient processing power, and appropriate network functions. For the fog-based healthcare system, data confidentiality, access control, and secure searching over ciphertext are the key issues in sensitive data. Furthermore, how to adjust the storage and computing requirements to meet the limited resource is also a great challenge for data management. To address these, we design a lightweight keyword searchable encryption scheme with fine-grained access control for our proposed healthcare related IoT-Fog-Cloud framework. Through our design, the users can achieve a fast and efficient service by delegating a majority part of the workloads and storage requirements to fogs and the cloud without extra privacy leakage. We prove our scheme satisfies the security requirements and demonstrate the excellent efficiency through experimental evaluation.
查看更多>>摘要：We consider a secrecy dual-hop amplify-and-forward (AF) untrusted relay network, where the relay is willing to forward the signal to the destination while acting as a potential eavesdropper. Assuming that all these nodes are equipped with multiple antennas, we propose a joint destination aided cooperative jamming and precoding at both the source and the relay scheme, with the objective to maximize the worst case secrecy rate. The formulated problem is highly non-convex due to the maximization of the difference of several logarithmic determinant (log-det) functions in the CSI uncertainty region. To handle this challenge, we propose to linearize these log-det terms. After linearization, we tackle the CSI uncertainty based on epigraph reformulation and the sign-definiteness lemma. Finally, an alternating optimization (AO) algorithm is proposed to solve the reformulated problem. Numerical results are provided to demonstrate the performance of the proposed scheme.
查看更多>>摘要：Bandwidth and power hungry applications are proliferating in mobile networks at a rapid pace. However, mobile devices have been suffering from a lack of sufficient battery capacity for the intensive/continuous use of these applications. In addition, the mobile ecosystem is currently heterogeneous and comprises a plethora of networks with different technologies such as LTE, Wi-Fi, and WiMaX. Hence, an issue must be addressed to ensure that quality of experience (QoE) is provided for the users in this scenario: an energy-efficient strategy that is designed to extend the battery lifetime of mobile devices. This paper proposes an architecture which provides an intelligent decision-making support system based on Fuzzy Logic for saving the energy of mobile devices within an integrated LTE and Wi-Fi network. The simulated experiments show the benefits of the solution this architecture can provide by using QoE metrics.
M. A. Gomez-NietoI. Jimena MedinaM. A. Gomez-LuqueJ. Pena Amaro...
16页
查看更多>>摘要：Despite the development of mobile device technology over recent years, its application in the field of teaching has not yet had a parallel development. For the past two decades teaching subjects such as histology has undergone a change in the digital use of its content and didactic methods based on Web applications, e-learning portals, etc., in which the use of high definition images enables the substitution of the light microscope for a "virtual microscope". This paper describes a mobile device solution based on the use of Near Field Communication technology for supporting teaching in medical histology. The didactic contents are managed in a database which stores information and images corresponding to the histological slides that are handed out to students in the glass slides for their analysis under a microscope. By associating a single NFC chip to each glass slide and touching this chip with a smartphone, students are given access to all the multimedia information related to the histological slides, without needing a mobile device. The system developed, called HistoNFC, enables access to this information at any moment, as well as the follow-up to the didactic activity and student evaluation. Evaluation of the system has been carried out by histology students of medical degree at the University of Cordoba, assessing aspects of the assisted-learning process as well as technologies, and the results obtained have been very favorable for both, as can be seen in detail in this study.
查看更多>>摘要：In this paper, power control in the uplink for two-tier small-cell networks is investigated. We formulate the power control problem as a Stackelberg game, where the macrocell user equipment (MUE) acts as the leader and the small-cell user equipment (SUE) acts as the follower. To reduce the cross-tier and cotier interferences and the power consumption of both the MUE and SUE, we propose optimizing not only the transmit rate but also the transmit power. The corresponding optimization problems are solved through a two-layer iteration. In the inner iteration, the SUE items (SUEs) compete with each other, and their optimal transmit powers are obtained through iterative computations. In the outer iteration, the optimal transmit power of the MUE is obtained in a closed form based on the transmit powers of the SUEs through proper mathematical manipulations. We prove the convergence of the proposed power control scheme, and we also theoretically show the existence and uniqueness of the Stackelberg equilibrium (SE) in the formulated Stackelberg game. The simulation results show that the proposed power control scheme provides considerable improvements, particularly for the MUE.
查看更多>>摘要：In this paper, we analyze requirements of next generation 112 emergency services in the era of ubiquitous mobile devices and sensors and present the design, implementation, and piloting results of our testbed, which was developed within the H2020 project NEXES. The system leverages a multihop location-aware PEMEA routing network that finds the geographically closest responsible public service answering point (PSAP) and supports cross-border application roaming. Our reference mobile implementation utilizes multiple device and network-based positioning technologies, which, combined, both outperform traditional cell-tower based positioning and provide a means for detecting fraudulent calls. The system is extensible and can establish a variety of communication channels after the initial emergency session is set up; we demonstrate this with an interoperable WebRTC-based video call. The obtained results demonstrate the viability and flexibility of PEMEA-based over-the-top emergency services, show high user acceptance when comparing them with existing solutions, and thus pave the road for further rollout of such systems.
查看更多>>摘要：Based on the measurement error of pseudorange in BeiDou satellite navigation system, this paper analyzes the measurement principle of the system. Aiming at the difficulties in the system measurement error index system, an overall construction method of measurement error system based on empirical estimation method and error distribution model is proposed. Based on the Analytic Hierarchy Process, the correlation analysis model of the measurement error index is constructed, the relationship between the indicators is analyzed, and the system measurement error index hierarchy is constructed. Based on the empirical estimation method and the error distribution model, the index values are decomposed and assigned based on the final service performance of the system, and a clear representation of the complex relationship of index matching is achieved. Finally, by analyzing the principle of the positioning function in the ground transportation control mode, taking the satellite clock error as an example, the model is decomposed layer by layer and the relevant indicator items are established. The relationship between index terms was studied, and the value of the indicators was quantified. Compared with the actual operating conditions of the current system, the correctness of the method was verified, which provided a basis for the demonstration of the index values of satellite navigation systems. Based on the empirical estimation method and error distribution model as a new type of calculation method, the index system established under a certain set of conditions is reasonable, and it can be applied to the error control adjustment in satellite navigation system engineering construction.
查看更多>>摘要：In mission and time critical applications, bandwidth and delay optimizations are the key goals of communication systems. This paper presents a cross-layer framework design that reduces the call setup time, provides collision-free communication, and reuses the empty slots of Time Division Multiple Access (TDMA) protocol which otherwise causes low throughput and large delay. As number of communicating nodes in tactical networks is small as compared to commercial mobile ad hoc networks (MANETs), classical TDMA will yield huge number of empty slots and any Carrier Sense Multiple Access/Collision Detection (CSMA/CD) technique may cause more delay in some critical scenarios. Proposed methodology gives a Cross-Layer Architecture for Network (NET) Layer and Medium Access Control (MAC) Layer. Our design provides bandwidth efficient, collision-free communication to Software-Defined Radios (SDRs) in self-forming and self-healing tactical networks with low call setup time and multihop routing. For this purpose TDMA as MAC layer protocol and Ad Hoc On Demand Distance Vector (AODV) as Network Layer Routing Protocol are used. Our slot allocation (SA) algorithm, Cross-Layer TDMA (CL-TDMA), consists of control phase where AODV control packets are exchanged and data transfer phase where transmission of data and voice occurs. All active radios in vicinity gather information about communicating nodes based on the exchange of control packets by SDRs. Our algorithm then uses this information to help all active SDRs find slot(s) that will be used for collision-free transmission. A number of experiments are performed to establish improved performance of the proposed technique compared to other established techniques and protocols.
查看更多>>摘要：This paper investigates the maximal ratio combining (MRC) performance of an amplify and forward (AF) relay system in Nakagami-m fading environments. The study considers a general scenario with distinct m fading parameters for the following three links, source to relay link, and source to destination link and relay to destination link. We derive new closed form expressions for the statistics of important performance metrics, including the moment generating function, outage probability, higher order moments of equivalent signal to noise ratio (SNR), ergodic capacity, and average symbol error probability (SEP) of common modulation types. In particular, we focus on analytical SEP expressions in the context of an additive white generalized Gaussian noise (AWGGN). As an active area of research, generalized noise receives much attention for its flexible model. However, analytical performance of modulation scheme in generalized noise type has not been found in open literature for AF relaying with MRC despite its practical usefulness. Without the help of analytical solutions, the SEP in generalized noise can only be obtained by a large number of repeated simulation experiments. Therefore, we present the general SEP expression by using special Fox's H function. Simulation results verify the accuracy of our theoretical analysis and show that the diversity order of MRC criterion linearly depends upon Nakagami parameters of three links.
查看更多>>摘要：This paper describes design and implementation of an OFDM-based digital video broadcasting system test platform for multichannel ultra-high definition (UHD) broadcasting services. The developed digital video broadcasting system test platform has been installed in commercial broadcasting station, and trial broadcasting service of the system has been performed through the commercial in-service network. For the performance measurement, field test is also executed. To evaluate the practical performance of the implemented system, a commercial broadcasting set-top box is used. Furthermore, by using measurement receiver, various system performances have been evaluated such as BER, PER, and CNR. Because high efficiency video coding (HEVC) can successfully transmit multimedia contents with a raw data rate of 51.6 Mbps, a multichannel UHD service can be serviced in a single physical 6MHz channel.
NSTL
Wiley-Hindawi