Search Results (17)

Accurate Doppler frequency estimation for Low Earth Orbit (LEO)-based Signals of Opportunity (SoOP) positioning faces significant challenges from extreme dynamics (±40 kHz Doppler shift, 0.4 Hz/ms fluctuation) and severe SNR fluctuations induced by multi-beam switching. Empirical analysis reveals that phased-array beamforming generates three-tiered SNR fluctuation patterns during unpredictable beam handovers, rendering conventional single-algorithm solutions fundamentally inadequate. To address this limitation, we propose KDFE (KNN-Driven Fusion Estimator)—an adaptive framework integrating the Rife–Vincent algorithm and MLE via intelligent switching. Global FFT processing extracts real-time Doppler-SNR parameter pairs, while a KNN-based arbiter dynamically selects the optimal estimator by: (1) Projecting parameter pairs into historical performance space, (2) Identifying the accuracy-optimal algorithm for current beam conditions, and (3) Executing real-time switching to balance accuracy and robustness. This decision model overcomes the accuracy-robustness trade-off by matching algorithmic strengths to beam-specific dynamics, ensuring optimal performance during abrupt SNR transitions and high Doppler rates. Both simulations and field tests demonstrate KDFE’s dual superiority: Doppler estimation errors were reduced by 26.3% (vs. Rife–Vincent) and 67.9% (vs. MLE), and 3D positioning accuracy improved by 13.6% (vs. Rife–Vincent) and 49.7% (vs. MLE). The study establishes a pioneering framework for adaptive LEO-SoOP positioning, delivering a methodological breakthrough for LEO navigation. Full article

In the realm of the fifth-generation (5G) wireless cellular networks, renowned for their dense connectivity, there lies a substantial facilitation of a myriad of Internet of Things (IoT) applications, which can be supported by the massive machine-type communication (MTC) technique, a fundamental communication framework. In some scenarios, a large number of machine-type communication devices (MTCD) may simultaneously enter the communication coverage of a target base station. However, the current handover mechanism specified by the 3rd Generation Partnership Project (3GPP) Release 16 incurs high signaling overhead within the access and core networks, which may have negative impacts on network efficiency. Additionally, other existing solutions are vulnerable to malicious attacks such as Denial of Service (DoS), Distributed Denial of Service (DDoS) attacks, and the failure of Key Forward Secrecy (KFS). To address this challenge, this paper proposes an efficient and secure handover authentication protocol for a group of MTCDs supported by blockchain technology. This protocol leverages the decentralized nature of blockchain technology and combines it with certificateless aggregate signatures to mutually authenticate the identity of a base station and a group of MTCDs. This approach can reduce signaling overhead and avoid key escrow while significantly lowering the risk associated with single points of failure. Additionally, the protocol protects device anonymity by encrypting device identities with temporary anonymous identity markers with the Elliptic Curve Diffie–Hellman (ECDH) to abandon serial numbers to prevent linkage attacks. The resilience of the proposed protocol against predominant malicious attacks has been rigorously validated through the application of the BAN logic and Scyther tool, underscoring its robust security attributes. Furthermore, compared to the existing solutions, the proposed protocol significantly reduces the authentication cost for a group of MTCDs during handover, while ensuring security, demonstrating commendable efficiency. Full article

In the last 20 years, research on the observed and projected impacts of climate change on cultural heritage has led to significant developments regarding damage quantification and risk assessment, which unfortunately are not yet exhaustively transferred to practical applications and to the sector of policy and decision making. One of the major reasons for this still lacking alignment remains with the inadequate handover of quantitative data, which is a prerequisite for the development of measures and strategies for the mitigation of the impacts and risk reduction. In this paper, we focus on the methods and approaches put in place for the production of projections providing quantitative assessments of climate change-induced impacts in the near and far future (up to the 21st century) on outdoor built heritage mainly constituted by stone and stone-like materials. Our critical study found that different approaches have been applied for quantifying slow cumulative damage due to the ongoing variations of climate and air pollution parameters and to risk assessment caused by hydrometeorological extreme events induced by variations of temperature and precipitation. There is clear evidence that efforts are still needed for directing research to provide concrete solutions and tools addressed to meet the requirements of stakeholders and to solve the existing challenges in the field: selected effective models and tools are illustrated. The discussion is structured in order to highlight the driving role of research in supporting the definition of priorities for heritage managers and the development of strategies by decision and policy makers for the prevention and safeguarding of cultural heritage at risk. Full article

The non-terrestrial network (NTN) is a network that uses radio frequency (RF) resources mounted on satellites and includes satellite-based communications networks, high altitude platform systems (HAPS), and air-to-ground networks. The fifth generation (5G) and NTN may be crucial in utilizing communication infrastructure to provide 5G services in the future, anytime and anywhere. Based on the outcome of the Rel-16 study, the 3rd generation partnership project (3GPP) decided to start a work item on an NTN in 5G new radio (NR) Rel-17, and the focus of the study was on mobility management procedures, due to the movements of NTN platforms; especially, low earth orbit (LEO) satellites. Handover enhancements were discussed to tackle the frequent handover due to the fast satellite movement. Therefore, the major problem of handover in LEO satellite systems was the signaling storm created by handing over all user equipment (UE) in a cell to a new cell because when the UE crosses the boundary between the neighboring cell of a satellite, an intra-satellite or cell handover occurs; thus, all users in a cell are expected to experience a change of cell due to handover every few seconds. In addition, UE location is not easy to define due to moving cell/beam situations. In this study, we propose machine learning-based solutions for handover decisions in non-terrestrial networks for cell handovers or intra-satellite handovers to reduce signaling storms during handovers where the handover requests will be executed by clustered users. First, the dataset was generated by the simulator that simulates communication between users and satellites. Second, we preprocessed the data, and also used the feature creation technique to create the distance feature using the Haversine formula, and then applied clustering and classification algorithms. The experimental results show that the distance between a user and its cell center is an important parameter for handover decisions in NTN, and the random forest outperforms all models with a higher accuracy of 99% along with a better F1-score of 0.9961. Full article

Nursing Bedside Handover (NBH) is acknowledged as a nursing practice implemented at the patient’s bedside to improve communication safety during the shift change, but it is vulnerable due to inconsistent application among nurses. This synthesis of qualitative evidence aims to review and synthesize the perceptions and experiences of nurses regarding the factors that, in their perspective, influence NBH practice. We will follow the thematic synthesis methodology of Thomas and Harden and the Enhancing Transparency in Reporting the Synthesis of Qualitative Research (ENTREQ) Statement guidelines. A search will be conducted through the databases of MEDLINE, CINAHL, Web of Science, and Scopus, and we will follow the three-step search process to identify primary studies with qualitative or mixed-method research designs and projects of quality improvement. The screening and selection of the studies will be carried out by two independent reviewers. We will use the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) to report the screening, search, and selection of studies. To assess its methodological quality, two reviewers will independently use the CASM Tool. The extracted data will be reviewed, categorized, and summarized in tabular and narrative formats. The findings obtained will allow us to inform future research and change management led by nurse managers. Full article

Services surrounding green buildings are specialised and directed towards the process of design and comprise comprehensive and quantified management in its entirety. Implicitly, consultancies are unable to deliver this service at the standard and pace required in the preliminary stages of design, and not all clients or consultants will require the services to be essential. The main aim is to stabilise the several characteristics prompting one another to optimise design performance against the optimisation algorithms. Green Star is a universal evaluation tool, assessing not only green characteristics but also elements that influence wellbeing and occupant health, such as indoor environment quality. The tools for Green Star rating can be used to measure the green features of a building from the design phase right to the stage of site handover (known as “As-Built”). This paper refers, in the literature review, to the passive and low-energy design methods of a Green Star-rated building at early design stages. The “green” project management of a project is to coordinate multidisciplinary incorporation and to accompany the costing contribution tools presented in this paper. The passive and low-energy design tools discussed entails the amalgamation of electrical and mechanical services together with architecture, i.e., space layout and envelope design. This paper compares rationalised energy and indoor environment performance between two buildings against the activities and climatic conditions within a targeted Green Star-rated building. Proposals regarding 4- and 6-star ratings and techniques have been evaluated and presented for the two buildings. Full article

This paper illustrates a methodological approach to optimize the data management process and to reduce costs related to information loss, from the preliminary phases to the Facility Management (FM) one. The growing concern about sustainability issues has steadily increased attention to cultural heritage’s key role. Concurrently, Europe promotes the application of digital methods for managing interventions both for new and existing buildings. The data issue, especially in heritage projects, represents a crucial aspect; data-recovering activities or shortages of information contribute to relevant expenses and discourage stakeholders. The research focuses on how procedures involving digitalization, applied to heritage projects, can improve the information workflow, supporting the hand-over stage. Although the application of digital techniques has recognized advantages, enhancements for optimizing time and cost savings are required. The research result is a methodological framework to obtain complete heritage as-built deliverables for the management phase. The defined structure is applied through a case study approach to the restoration of a historical lyric theater. Thus, the as-built model represents a database for controlling costs and maintenance procedures. In the end, the work provides a tangible contribution to the Heritage BIM (HBIM) delivery and can be a starting point for future improvements. Full article

Sharing network infrastructure is carried out by a few network operators in the world and is regarded as an effective means to accelerate the commercial 5G with seamless coverage and user experience guarantees but significantly reduced investment. Voice via IMS has been defined as the voice-bearing solution from 3rd-Generation Partnership Project (3GPP) Release 5. Release 15 pointed out that 5G still adopts the IMS-based voice service architecture. In such a background, and in the process of global 5G network evolution from non-stand-alone (NSA) to stand-alone (SA), how to bear 5G voice services in the sharing network infrastructure has quite a few technical options. This paper investigates the 5G access network sharing technical solutions and presents the voice bearer technology under different new radio (NR) evolution stages. Analysis was performed for the different stages of voice handover. Performance results from field tests are provided to verify the feasibility of the solution, and performance analysis such as end-to-end call setup delay was also carried out. From the theoretical and practical analysis, the voice over long-term evolution (VoLTE) non-back-to-home solution has a relatively short access delay in the NSA sharing stage; EPS fallback based on either handover or redirection introduces a large time delay, so EPS fallback can only be used as a transition solution in the early stage of SA sharing deployment; voice over new radio (VoNR) has the lowest access time delay and the simplest implementation solution, so it is the final voice solution for 5G SA sharing network. The comparison of different voice-bearing solutions in different network development stages provides a reference for countries around the world. Full article

This paper addresses critical success factors for the delivery of BIM projects. The lack of experience with BIM projects on both the demand and supply side often leads to insufficient project teams, unsatisfied clients, schedule, and cost overruns. In order to better structure and control the information delivery in BIM projects requirements, planning and delivery must be standardized. The latter was achieved by EIR (Exchange Information Requirements), new BIM roles, BEP (BIM Execution Plan), and specified digital handover, which must be supported by a common data environment (CDE). This paper provides an analysis of the characteristics of BIM project delivery and duration in Architectural and Engineering companies in Slovakia. The analysis is based on the web survey of BIM managers and coordinators, which reveals that a significant amount of BIM project efforts must be executed by BIM specialists. The results also graphically depict the scope of critical BIM activities across project phases. The presented study is relevant for various project stakeholders and allows for a deeper understanding of the resources needed for the successful delivery of BIM projects in terms of adequate project team capacity, capability, organization, and planning. Full article

Recently, the construction industry has seen an increase in construction program level projects in which a number of projects are carried out simultaneously. These projects thus require more systematic management than traditional management methods due to both their complexity and the diverse stakeholders involved. When multiple projects overlap at the same time, it can create a gap between the contractor’s results and the user’s expectations at the closure phase of the construction program. These can include situations such as when handover is delayed, conflicts and frictions occur, and complaints from users mount. Therefore, an approach is needed to increase user satisfaction at the program level. This study presents a systematic closing management plan to increase user satisfaction for a smoother handover at the closure phase. The closure process was identified through case studies of activities in the closure phase. In addition, after identifying the stakeholder groups participating in the closure phase, responsibilities and roles were proposed as RACI (Responsible, Accountable, Consulted, and Informed) models by mapping the closure phase of processes and stakeholders. This model shows who is responsible and accountable for, consulted on, and informed about work processes in the closure phase of the program. From a user’s point of view, program closure signifies the beginning of operation and maintenance. We intend to contribute to the increase of user satisfaction by suggesting when and in what work activities the user will be involved in construction products from the user’s perspective. Full article

The multipath transmission control protocol (MPTCP) is considered a promising wireless multihoming solution, and the 3rd generation partnership project (3GPP) includes it as a standard feature in the fifth-generation (5G) networks. Currently, ns-3 (Network Simulator-3) is widely used to evaluate the performance of wireless networks and protocols, including the emerging MPTCP protocol. This paper investigates the fidelity of the Linux kernel implementation of MPTCP in the ns-3 direct code execution module. The fidelity of MPTCP simulation is tested by comparing its performance with a real Linux stack implementation of MPTCP using a hardware testbed for two different setups. One setup emulates the existence of a bottleneck link between the sending and receiving networks, whereas the other setup does not have such a bottleneck. The fidelity of ns-3’s simulation is tested for four congestion control algorithms, namely Cubic, linked-increases algorithm (LIA), opportunistic LIA (OLIA) and wVegas for relatively short and long data flows. It is found that the uplink MPTCP throughput performance exhibited by the ns-3 simulator matches the hardware testbed results only if the flows are long-lived and share no common bottleneck link. Likewise, the MPTCP throughput achieved during a downlink scenario using the ns-3 simulator and the hardware testbed are close to each other across all algorithms except wVegas regardless of the flow size if there is no bottleneck link. Moreover, it is observed that the impact of LTE handover on MPTCP throughput is less significant in the simulator than the real hardware testbed, and it is setup-dependent. Full article

With the increasing number of nearly zero-energy buildings (NZEB) due to increase of global awareness on climate change, the new concepts of design and control must be developed because of great NZEB dependency on detailing and multidisciplinary approach. This paper proposes a three-level gateway control method for NZEB project delivery by using digital representation of the building in building information modeling (BIM) environment. These controls (C1, C2 and C3) are introduced before three main phases of any project delivery—design phase, construction phase and handover. The proposed project control procedure uses black-box building energy modeling within the BIM environment, so the paper explores the reliability of one tool for direct energy modeling within the BIM-authoring software. The paper shows two types of validation tests with satisfactory results. This leads to conclusion that analyzed tool for energy simulation within BIM environment can be used in a way that is described in a proposed project control procedure. For further research it is proposed to explore reliability of tools for energy simulation connected to other BIM-authoring software, so this project control procedure could be independent of BIM-authoring software used in the paper. Full article

This study addresses the handover management issue for Device-to-Device communication in fifth-generation (5G) networks. The Third Generation Partnership Project (3GPP) drafted a standard for proximity services (ProSe), also named device-to-device (D2D) communication, which is a promising technology in offering higher throughput and lower latency services to end users. Handover is an essential issue in wireless mobile networks due to the mobility of user equipment (UE). Specifically, we need to transfer an ongoing connection from an old E-UTRAN Node B (eNB) to a new one, so that the UE can retain its connectivity. In the data plane, both parties of a D2D pair can communicate directly with each other without the involvement of the base station. However, in the control plane, devices must be connected to the eNB for tasks such as power control and resource allocation. In the current standard of handover scheme, the number of unnecessary handovers would be increased by the effect of shadowing fading on two devices. More important, the handover mechanism for D2D pairs is not standardized yet. LTE-A only considers the handover procedure of a single user. Therefore, when a D2D pair moves across cell boundaries, the control channels of the two UEs may connect to different base stations and result in increased latency due to the exchange of D2D related control messages. Hence, we propose a handover management scheme for D2D communication to let both parties of a D2D pair handover to the same destination eNB at the same time. By doing so, the number of unnecessary handovers, as well as the handover latency, can be reduced. In the proposed method, we predict the destination eNB of D2D users based on their movements and the received signal characteristics. Subsequently, we make a handover decision for each D2D pair by jointly factoring in the signal quality and connection stability. Expected improvement can be attained, as revealed in the simulation. Unnecessary handover can be avoided. Consequently, both UEs of a D2D pair reside in the same cell and, therefore, result in increased throughput and decreased delay. Full article

How much information with regard to identity and further individual participant
characteristics are revealed by relatively short spatio-temporal motion trajectories of a person?
We study this question by selecting a set of individual participant characteristics and analysing
motion captured trajectories of an exemplary class of familiar movements, namely handover of an
object to another person. The experiment is performed with different participants under different,
predefined conditions. A selection of participant characteristics, such as the Big Five personality
traits, gender, weight, or sportiness, are assessed and we analyse the impact of the three factor groups
“participant identity”, “participant characteristics”, and “experimental conditions” on the observed
hand trajectories. The participants’ movements are recorded via optical marker-based hand motion
capture. One participant, the giver, hands over an object to the receiver. The resulting time courses of
three-dimensional positions of markers are analysed. Multidimensional scaling is used to project
trajectories to points in a dimension-reduced feature space. Supervised learning is also applied.
We find that “participant identity” seems to have the highest correlation with the trajectories, with
factor group “experimental conditions” ranking second. On the other hand, it is not possible to find a
correlation between the “participant characteristics” and the hand trajectory features. Full article

The workflow in historic architecture projects presents problems related to the lack of clarity of processes, dispersion of information and the use of outdated tools. Different heritage organisations have showed interest in innovative methods to resolve those problems and improve cultural tourism for sustainable economic development. Building Information Modelling (BIM) has emerged as a suitable computerised system for improving heritage management. Its application to historic buildings is named Historic BIM (HBIM). HBIM literature highlights the need for further research in terms of the overall processes of heritage projects, its practical implementation and a need for better cultural documentation. This work uses Design Science Research to develop a protocol to improve the workflow in heritage interdisciplinary projects. Research techniques used include documentary analysis, semi-structured interviews and focus groups. HBIM is proposed as a virtual model that will hold heritage data and will articulate processes. As a result, a simple and visual HBIM protocol was developed and applied in a real case study. The protocol was named BIMlegacy and it is divided into eight phases: building registration, determine intervention options, develop design for intervention, planning the physical intervention, physical intervention, handover, maintenance and culture dissemination. It contemplates all the stakeholders involved. Full article