A Multidimensional Reputation Evaluation Model for Mobile Crowd Sensing

The participant's reputation is vital to improve the quality of service for Mobile Crowd Sensing (MCS). A multidimensional reputation evaluation model was proposed in this paper to evaluate the participant's reputation more objectively. Different from the existing strategies, the service delay and the count of the successful as well as the failed transactions were additionally utilized to evaluate the participant's reputation. An algorithm based on Analytic Hierarchical Process (AHP) was presented to establish the reputation evaluation weight matrix. Besides, a fuzzy logic based mechanism was proposed to normalize the value of the four criteria and a dual-threshold mechanism was designed to achieve admission control more properly. Finally, extensive simulations were conducted and the simulation results confirmed the effectiveness of the reputation evaluation model

UTM-Chain: Blockchain-Based Secure Unmanned Traffic Management for Internet of Drones

Unmanned aerial systems (UAVs) are dramatically evolving and promoting several civil applications. However, they are still prone to many security issues that threaten public safety. Security becomes even more challenging when they are connected to the Internet as their data stream is exposed to attacks. Unmanned traffic management (UTM) represents one of the most important topics for small unmanned aerial systems for beyond-line-of-sight operations in controlled low-altitude airspace. However, without securing the flight path exchanges between drones and ground stations or control centers, serious security threats may lead to disastrous situations. For example, a predefined flight path could be easily altered to make the drone perform illegal operations. Motivated by these facts, this paper discusses the security issues for UTM's components and addresses the security requirements for such systems. Moreover, we propose UTM-Chain, a lightweight blockchain-based security solution using hyperledger fabric for UTM of low-altitude UAVs which fits the computational and storage resources limitations of UAVs. Moreover, UTM-Chain provides secure and unalterable traffic data between the UAVs and their ground control stations. The performance of the proposed system related to transaction latency and resource utilization is analyzed by using cAdvisor. Finally, the analysis of security aspects demonstrates that the proposed UTM-Chain scheme is feasible and extensible for the secure sharing of UAV data

Challenges and Approaches in Green Data Center

Cloud computing is a fast evolving area of information and communication technologies (ICTs)that hascreated new environmental issues. Cloud computing technologies have a widerange ofapplications due to theirscalability, dependability, and trustworthiness, as well as their abilityto deliver high performance at a low cost.The cloud computing revolution is altering modern networking, offering both economic and technologicalbenefits as well as potential environmental benefits. These innovations have the potential to improve energyefficiency while simultaneously reducing carbon emissions and e-waste. These traits have thepotential tomakecloud computing more environmentally friendly. Green cloud computing is the science and practise of properlydesigning, manufacturing, using, and disposing of computers, servers,and associated subsystems like displays,printers, storage devices, and networking and communication systems while minimising or eliminatingenvironmental impact. The most significant reason for a data centre review is to understand capacity,dependability, durability,algorithmic efficiency, resource allocation, virtualization, power management, andother elements. The green cloud design aims to reduce data centre power consumption. The main advantageof green cloud computing architecture is that it ensures real-time performance whilereducing IDC’s energyconsumption (internet data center).This paper analyzed the difficultiesfaced by data centers such as capacityplanning and management, up-time and performance maintenance, energy efficiency and cost cutting, realtime monitoring and reporting. The solution for the identified problems with DCIM system is also presentedin this paper. Finally, it discusses the market report’s coverage of green data centres, green computingprinciples, andfuture research challenges. This comprehensive green cloud analysis study will assist nativegreen research fellows in learning about green cloud concerns and understanding future research challengesin the field

Improved Recursive DV-Hop Localization Algorithm with RSSI Measurement for Wireless Sensor Networks

Abstract: Please refer tp full text to view abstrac

Theoretical Performance Bound of Uplink Channel Estimation Accuracy in Massive MIMO

In this paper, we present a new performance bound for uplink channel estimation (CE) accuracy in the Massive Multiple Input Multiple Output (MIMO) system. The proposed approach is based on noise power prediction after the CE unit. Our method outperforms the accuracy of a well-known Cramer-Rao lower bound (CRLB) due to considering more statistics since performance strongly depends on a number of channel taps and power ratio between them. Simulation results are presented for the non-line of sight (NLOS) 3D-UMa model of 5G QuaDRiGa 2.0 channel and compared with CRLB and state-of-the-art CE algorithms.Comment: accepted for presentation in a poster session at the ICASSP 2020 conferenc

High Performance Interference Suppression in Multi-User Massive MIMO Detector

In this paper, we propose a new nonlinear detector with improved interference suppression in Multi-User Multiple Input, Multiple Output (MU-MIMO) system. The proposed detector is a combination of the following parts: QR decomposition (QRD), low complexity users sorting before QRD, sorting-reduced (SR) K-best method and minimum mean square error (MMSE) pre-processing. Our method outperforms a linear interference rejection combining (IRC, i.e. MMSE naturally) method significantly in both strong interference and additive white noise scenarios with both ideal and real channel estimations. This result has wide application importance for scenarios with strong interference, i.e. when co-located users utilize the internet in stadium, highway, shopping center, etc. Simulation results are presented for the non-line of sight 3D-UMa model of 5G QuaDRiGa 2.0 channel for 16 highly correlated single-antenna users with QAM16 modulation in 64 antennas of Massive MIMO system. The performance was compared with MMSE and other detection approaches.Comment: Accepted for presentation at the VTC2020-Spring conferenc

A comparison of automated time series forecasting tools for smart cities

Most smart city sensors generate time series records and forecasting such data can provide valuable insights for citizens and city managers. Within this context, the adoption of Automated Time Series Forecasting (AutoTSF) tools is a key issue, since it facilitates the design and deployment of multiple TSF models. In this work, we adapt and compare eight recent AutoTSF tools (Pmdarima, Prophet, Ludwig, DeepAR, TFT, FEDOT, AutoTs and Sktime) using nine freely available time series that can be related with the smart city concept (e.g., temperature, energy consumption, city traffic). An extensive experimentation was carried out by using a realistic rolling window with several training and testing iterations. Also, the AutoTSF tools were evaluated by considering both the predictive performances and required computational effort. Overall, the FEDOT tool presented the best overall performance.This work has been supported by FCT - Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020 and the project “Integrated and Innovative Solutions for the well-being of people in complex urban centers” within the Project Scope NORTE-01-0145-FEDER-000086

Joint Power and Channel Allocation for Underlay D2D Communications with Proportional Fairness

Since D2D (Device-to-Device) communication was proposed in cellular network as a new paradigm for enhancing network performance, many works have been done on resource allocation to improve system throughput and energy efficiency (EE) for underlay D2D communications. However, the system long-term average fairness as one of the system main performance metrics was rarely considered especially when users are moving. In this paper, we formulate the joint power and channel allocation problem aiming at maximizing the system fairness subject to the minimum required SINRs (Signal to Interference and Noise Ratios) and power consumption limits of cellular and active D2D links. To solve the above problem practically, we first decompose our original problem into two sub-problems (power and channel allocation), then solve them sequentially. Simulation results show that our proposed algorithm can dramatically enhance the system fairness and slightly improve the system throughput comparing with existing method