Handoff Performance Research Articles

Implementation of Vertical Handoff Over LTE, Wi-Fi and WiMAX Networks

The forthcoming wireless networks provide the continuous services to their users for different applications by the integration of diverse wireless access technologies known as heterogeneous wireless network. The heterogeneous wireless network improves the Quality of Service for stationary and non-stationary mobile users. Even when users are in mobility the services are provided by means of handoff or handover. In this paper, the integration of three different wireless networks such as LTE, WiMAX and Wi-Fi networks and their vertical handoff performance analysis are presented. These diverse wireless networks which are considered for integration are modeled as a heterogeneous wireless network. This network is designed using QualNet simulator. Furthermore, the designed heterogeneous network, vertical handoff performance is estimated by using factors such as throughput, jitter and End to End delay. With these performance factors, the designed network’s Quality of Service (QoS) is estimated under mobility conditions.

Hybrid Spectrum Handoff Scheme of Imperfect Sensing in Cognitive Radio Networks

Background: In the actual cognitive radio network, there exist the imperfect sensing such as false alarm and missed detection which can lead to the inaccurate spectrum handoff and cause more uncertain problems. Meanwhile, the predetermined target channel has high risk of being unavailable in the proactive-decision spectrum handoff scheme. Objective: To solve the problem that the state of the predetermined target channel is updated in the proactive-decision spectrum handoff scheme, we present a novel hybrid spectrum handoff scheme based on Preemptive Resume Priority (PRP) M/G/m queuing network model in this paper. Methods: The proposed scheme combines the advantages of proactive-decision spectrum handoff and reactive-decision spectrum handoff, and performs the spectrum sensing during the waiting time of the cognitive user on the target channel. On this basis, we consider the influence of multiple cognitive users, multiple authorization channels, multiple spectrum handoffs and other factors on the spectrum handoff delay of cognitive user. Then, the detailed analysis and derivations of cognitive user’s extended data delivery time are conducted. Furthermore, the effect of imperfect spectrum sensing on the spectrum handoff performance of cognitive users is discussed. Results: Compared with traditional spectrum handoff schemes, numerical results show that the extended data delivery time of the proposed scheme is smaller, and the performance of spectrum handoff is further improved. In addition, the performance of the proposed scheme is less affected by the probability of false alarm and missed detection with frequent channel states variations. Simulation results are given to validate the analytical results. Conclusion: The hybrid spectrum handoff scheme provide better performance on the spectrum sharing between primary users and cognitive users in cognitive radio network under imperfect sensing condition.

MM-PNEMO: a mathematical model to assess handoff delay and packet loss

Wireless networks incorporate Mobile Nodes (MNs) that use wireless access networks to communicate. However, the communication among these MNs are not remained stable due to the poor network coverage during inter mobility. Moreover, the wireless nodes are typically small that results in resource-constrained. Thus, it is uphill to use algorithms having giant processing power or memory footprint. Accordingly, it is essential to check schemes consistently to evaluate the performance within the probable application scenario. To do so, numerical analysis could be a notable method to grasp the performance of mobility management schemes as well as the constraint of evolving mobility management solutions specifically for multi-interfaced MR in Proxy NEMO environment. This paper analyzes handoff performance by using a mathematical model of Multihoming-based scheme to support Mobility management in Proxy NEMO (MM-PNEMO) environment. Moreover, a comparative study has been made among the standard Network Mobility Basic Support Protocol (NEMO BSP), Proxy NEMO (PNEMO) and MM-PNEMO scheme respectively. The performance metrics estimated for these schemes are mainly handoff delay and packet loss. This paper also analysed the packet loss ratio and handoff gain as a function of cell radius, number of SMR and velocity respectively. It is apparent that, the MM-PNEMO scheme shows lower packet loss ratio (1%) compared to NEMO-BSP (11%) and P-NEMO (6%).

Performance analysis of spectrum handoff under heterogeneous spectrum environment in ad hoc and centralized CR networks

The prime objective of cognitive radio (CR) is to address the problem of spectrum scarcity and inefficient usage of spectrum, by allowing the unlicensed or cognitive users (CUs) to access the underutilized licensed spectrum of the primary users (PUs). CUs experience considerable performance degradation due to the event of random interruptions by PUs in their respective bands of operation. In this article, we develop a spectrum management scheme and evaluate the performance of the CUs under heterogeneous spectrum environment (HetSE) in both ad-hoc (opportunistic) and centralized (negotiated) CR networks. We consider a finite threshold period (Dth) for spectrum handoff delay to improve the performance of the CUs for both opportunistic situation with backup channels (OSB) and negotiated situation with backup channels (NSB). The spectrum handoff performance measuring metrics: link maintenance probability, link failure probability, probability mass function of spectrum handoff, expected number of spectrum handoff and non-completion probability of the CUs, are derived under heterogeneous spectrum environment to investigate the characteristics of the network for both opportunistic and negotiated spectrum access strategies.

An IMS-Based Advanced Handoff Scheme for Wi-Fi/LTE Integrated Framework

Integrating heterogeneous access technologies to provide users with always best connected services is one of the primary objectives of fourth-generation wireless technologies. The major research issue in an integrated framework is to enable mobile users with fast and smooth connectivity while switching between heterogeneous access technologies. In this paper, an integration framework for Wireless Fidelity/Long-Term Evolution access technologies is presented with IP Multimedia Subsystem for service provisioning. An inter-domain handoff scheme called SIP advanced handoff is proposed which utilizes improved Session Initiation Protocol (SIP) and Mobile IPv6 with a multilayer approach which enables fast and smooth connectivity with minimized handoff latency and improved throughput. A simulation is carried out using NS2, and the performance characteristics are studied. The measured handoff performance metrics reveal that successful video session handoffs are achieved with acceptable quality of services levels and further that the proposed scheme shows better performance than the conventional scheme.

Coverage and Handoff Analysis of 5G Fractal Small Cell Networks

It is anticipated that much higher network capacity will be achieved by the fifth generation (5G) small cell networks incorporated with the millimeter wave (mmWave) technology. However, mmWave signals are more sensitive to blockages than signals in lower frequency bands, which highlights the effect of anisotropic path loss in network coverage. According to the fractal characteristics of cellular coverage, a multi-directional path loss model is proposed for 5G small cell networks, where different directions are subject to different path loss exponents. Furthermore, the coverage probability, association probability, and the handoff probability are derived for 5G fractal small cell networks based on the proposed multi-directional path loss model. Numerical results indicate that the coverage probability with the multi-directional path loss model is less than that with the isotropic path loss model, and the association probability with long link distance, e.g., 150m, increases obviously with the increase of the effect of anisotropic path loss in 5G fractal small cell networks. Moreover, it is observed that the anisotropic propagation environment is having a profound impact on the handoff performance. Meanwhile, we could conclude that the resulting heavy handoff overhead is emerging as a new challenge for 5G fractal small cell networks.

A Novel SDN-based Cross Handoff Scheme in Industrial Mobile Networks

Supporting smooth handoff management in integrated smart factory architecture is an important issue. Existing handoff management protocols are not enough to ensure handoff support for Industrial Networks applications. SDN-Based Industrial Cross Handoff (SBICH) protocol technique was developed to support efficient handoff management between Industrial Networks. SBICH supports mobility management in wireless network environment and uses mobile speed and handoff signaling delay information to improve handoff performance. We analyze this handoff performance. This analysis shows that the performance is quite high.

Efficient Producer Mobility Management Model in Information-Centric Networking

Information centric networking is a clean-slate Internet architecture designed as a future Internet to supplement and completely replace the current Internet architecture. The future Internet information-centric networking was proposed in different kind of approaches to offered vast advantages ranging from security, catching, and content mobility support. However, some of the approaches support only content consumer, while content producer mobility faces many challenges, such as unnecessary Interest packet losses, high handoff latency, scalability issues, and high signaling overhead. Therefore, many approaches, protocols, and schemes were proposed to address the problem. The schemes such as indirection-based approach, locator-based approach, rendezvous-based, forwarding-based, and control/data plane-based, and mapping-based approach were investigated using either analytical or simulation investigation. However, in many cases of the formulation of an analytical investigation for information-centric networking mobility support management, the determination and incorporation of producers' movement behavior are neglected, whereas the movement pattern of mobile content producer plays a vital role in mobility performance analysis of the wireless mobile network. This paper proposed a producer mobility management model for information-centric networking with a random waypoint and random walk mobility model incorporated, to measure the movement pattern effect and proved the uniformity of the proposed model to support any kind of mobility support approaches or schemes. The performance analysis result of our proposed model revealed that movement pattern does affect the mobile producer handoff performance. Hence, for the accuracy of handoff latency, handoff signaling cost, and data packets delivery cost investigation, mobility models must be selected carefully based on the application domain.

Design and Performance Evaluation of Content-Oriented Communication System for IoT Network: A Case Study of Named Node Networking for Real-Time Video Streaming System

Information-Centric Networking (ICN) was born in an era that more and more users are shifting their interests to the content itself rather than the location where contents are stored. This paradigm shift in the usage patterns of the Internet, along with the urgent needs for content naming, pervasive caching, better security, and mobility support, has prompted researchers to consider a radical change to the Internet architecture. However, ICN is still in its infancy and development stage, and many issues still exist and need to be addressed. The common ICN architecture is lacking the host-centric communication ability and difficult to provide seamless mobility in current solutions. To solve this problem, our team had proposed the Named-Node Networking (3N) concept, which not only naming the content but also naming the node and it proved to have better performance of providing seamless mobility in the simulation. However, the previous contributions were limited in the 3N namespace for seamless mobility support in both producer and consumer. In this paper, we have proposed a 3N system which includes 3N naming, data delivery, mobility support, and data security. Moreover, we have created a 3N-based real-time video streaming system to evaluate data delivery performance and mobility handoff performance. The evaluation result proofs that our system performs better than TCP video streaming in a multi-client situation and a WiFi-based handoff was demonstrated.

"All the ward's a stage": a qualitative study of the experience of direct observation of handoffs.

Direct observation of clinical skills is central to assessment in a competency-based medical education model, yet little is known about how direct observation is experienced by trainees and observers. The objective of the study is to explore how direct observation was experienced by residents and faculty in the context of the I-PASS Handoff Study. In this multi-center qualitative study, we conducted focus groups and semi-structured interviews of residents and faculty members at eight tertiary pediatric centers in North America that implemented the I-PASS Handoff Bundle. We employed qualitative thematic analysis to interpret the data. Barriers to and strategies for direct observation were described relating to the observer, trainee, and clinical environment. Residents and faculty described a mutual awareness that residents change their performance of handoffs when observed, in contrast to their usual behavior in a clinical setting. Changes in handoff performance may depend on the nature of the observer or 'audience'. Direct observation also highlighted the importance of handoffs to participants, recognized as a clinical activity that warrants feedback and assessment. Dramaturgical theory can be used to understand our finding of 'front-stage' (observed) versus 'backstage' (unobserved) handoffs as distinct performances, tailored to an "audience". Educators must be cognizant of changes in performance of routine clinical activities when using direct observation to assess clinical competence.

A Standardized Handoff Simulation Promotes Recovery From Auditory Distractions in Resident Physicians.

Despite the increasing use of training simulations to teach and assess resident handoffs, simulations that approximate realistic hospital conditions with distractions are lacking. This study explores the effects of a novel simulation-based training intervention on resident handoff performance in the face of prevalent hospital interruptions. After a preliminary educational module, entering postgraduate year 1 residents (interns) completed one of the following three handoff simulations: (1) no interruption, (2) hospital noise, or (3) noise and pager interruptions. Trained receivers rated interns using an evidence-based Handoff Behaviors Checklist and a previously validated Handoff Mini-Clinical Examination Exercise instrument. Of 127 eligible interns, 125 (98.4%) completed an online preparatory module and a handoff simulation. Interns receiving auditory interruptions were less likely to be heard adequately (48.8% noise and 71.8% noise + pager vs. 100.0% uninterrupted, P < 0.001) and scored lower on establishing appropriate handoff settings (5.7 ± 2.3 noise and 6.2 ± 1.8 noise + pager vs. 8.0 ± 0.8 uninterrupted, P < 0.001). Interns receiving noise only shared a written sign-out document more effectively (71.1% vs. 30.2% uninterrupted and 43.6% noise + pager, P < 0.001). There were no differences in averaged performance metrics on the Handoff Behaviors Checklist. While common hospital interruptions created nonideal circumstances for the handoff, interns receiving interruptions were rated similarly and recovered effectively. However, interns exposed to noise only used the written sign-out form more actively. Our findings suggest that this intervention was successful in promoting handoff proficiency despite exposure to common but significant hospital interruptions.

Patientenübergaben in der Ausbildung? Eine systematische Analyse des Trainingsbedarfs unter Medizinstudierenden

BackgroundInsufficient handoffs lead to an increase in the risk of complications and malpractice, treatment delays, prolonged hospital stays, costs and patient complaints. The German Society for Anesthesiology and Intensive Care (DGAI) and the European Resuscitation Council (ERC) recommend the implementation of a communication procedure according to the SBAR concept. So far, there have been few curricular requirements in Germany regarding handoffs. MethodsAs part of the EU-funded PATIENT project an online-based cross-sectional needs analysis was conducted in three countries. In Aachen, 237 medical students answered 45 items concerning handoffs in three sections: A: skills (relevance and self-assessment), B: clinical experience (agreement), C: curricula content (presence and relevance). Data was recorded using a Likert scale (0–7). ResultsThe students rated an adequate handoff performance as highly important (M=6.8; SD: ±0.6) and their own expertise as low (M=4.0; SD: ±1.3). A high training need was identified for writing discharge letters and performing accurate handoffs. The students were aware of the link between adequate handoffs and patient safety (M=6.5; SD: ±0.9). They considered standardized handoff procedures as an important curricular component (M=6.1; SD: ±1.1). From their point of view, the handling of medical errors is underrepresented in the curriculum (61.7 %). ConclusionA need for handoff training was revealed, especially regarding transfers and discharges. Accordingly, learning objectives were determined and training modules developed and integrated into the curriculum in Aachen.

Impact of residual time distributions of spectrum holes on spectrum handoff performance with finite switching delay in cognitive radio networks

Cognitive radio technology ascends as a mean to improve the overall spectrum efficiency by exploring the spectrum opportunity and sharing the available channels with secondary users or cognitive users without causing harmful interference to either of the networks. Spectrum handoff is appeared to be a key strategy in order to ensure the required QoS of the primary user network and increase the overall performance of Cognitive Radio Network (CRN). In this paper, we investigate the effect of finite handoff or switching delay on the performance of spectrum mobility in a cognitive radio network. We establish an analytical model for the probability of spectrum handoff and develop an analytical formula of average spectrum handoff of a cognitive user for general residual time distributions of spectrum holes considering finite switching delay. The impact of switching delay and residual time distributions of spectrum holes on performance measuring metrics are investigated. This paper also presents a detailed comparison of results between the proposed time relationship model of spectrum handoff with and without finite switching delay in cognitive radio networks. A close proximity of the simulation result with the analytical one validates the accuracy of the proposed model.

Utility aware network selection in small cell

In fifth generation heterogeneous network, small cell is developed to compensate the growing demand for mobile data services. Due to the smaller size of cell, users have a short duration of connection, however, the user may also have the need of handoff frequently. At the time of handoff, different networks are available with different data rate and different other parameters. So, there is the need of frequent selection for the optimal network. In this paper, a utility-aware optimization algorithm has been proposed for network selection in a heterogeneous environment of Wi-Fi, WiMAX, WLAN, LTE, UMTS, and GPRS network. The weight factor is proposed for modified Jaya algorithm which is calculated by the analytical hierarchical process, standard deviation, and entropy method. Different applications are considered such as video, voice, web browsing and email transfer in which available bandwidth, packet jitter, packet loss, cost per byte are taken as dominant attributes, respectively. According to the dominant factor, different networks are selected for different applications because the requirement of all applications cannot be fulfilled by one network. Finally, the proposed algorithm is compared with multi-attribute decision making algorithms and game theory and accuracy of the proposed algorithm is calculated. The accuracy of proposed algorithm is higher as compared to the other algorithms and at the same time, this algorithm requires less computation which can further reduce the handoff latency and failure probability. Hence, the performance of handoff can be improved by using modified Jaya algorithm.

A Reliable Handoff Mechanism for Mobile Industrial Wireless Sensor Networks.

With the prevalence of low-power wireless devices in industrial applications, concerns about timeliness and reliability are bound to continue despite the best efforts of researchers to design Industrial Wireless Sensor Networks (IWSNs) to improve the performance of monitoring and control systems. As mobile devices have a major role to play in industrial production, IWSNs should support mobility. However, research on mobile IWSNs and practical tests have been limited due to the complicated resource scheduling and rescheduling compared with traditional wireless sensor networks. This paper proposes an effective mechanism to guarantee the performance of handoff, including a mobility-aware scheme, temporary connection and quick registration. The main contribution of this paper is that the proposed mechanism is implemented not only in our testbed but in a real industrial environment. The results indicate that our mechanism not only improves the accuracy of handoff triggering, but also solves the problem of ping-pong effect during handoff. Compared with the WirelessHART standard and the RSSI-based approach, our mechanism facilitates real-time communication while being more reliable, which can help end-to-end packet delivery remain an average of 98.5% in the scenario of mobile IWSNs.

Neighboring vehicle-assisted fast handoff for vehicular fog communications

With the fast development of vehicular technology and the emergence of mobile applications, it has become urgent to connect moving vehicles to Internet due to the ever-growing user demands. As an emerging paradigm of Internet of vehicles (IoV), vehicular fog communication (VFC) can not only efficiently enable drivers to access traditional Internet multimedia services, but also possible to enjoy new Internet applications dedicated to intelligent transportations. However, in VFC, travelling vehicles move with a high velocity and change their points of attachment frequently, which results in frequent network handoffs and even connection interruptions. In order to provide a satisfactory user experience, and enable vehicles to keep always-on-line connections when they are moving along urban roads, this paper proposes a cross-layer and neighboring vehicle-aided fast handoff (CVFH) scheme. A vehicle in CVFH utilizes the neighboring vehicle’s assistance to find a qualified vehicle to determine the target AP, and get related information before the vehicle moves into the coverage of the target AP. Simulation results show that the proposed scheme can improve the handoff performance in terms of handoff delay and throughput.

Human-centered automation for resilient nuclear power plant outage control

Abstract Nuclear power plant (NPP) outages are challenging construction projects. Delays in NPP outage processes can cause significant economic losses. In typical NPP outages, extremely busy outage schedules, large crew sizes, dynamic workspaces and zero tolerance of accidents pose challenges to ensuring the resilience of outage control, which should rapidly and proactively respond to delays, errors, or unexpected tasks added during outages. Two mutually interacting practical problems impede NPPs from achieving such resilient outage control: 1) how to control errors and wastes effectively during the “handoffs” between tasks, and 2) how to respond to numerous contingencies in NPP outage workflows in a responsive and proactive manner. A resilient NPP outage control system should address these two practical problems through “Human-Centered Automation (HCA),” which is improving the control process automation while fully considering human factors. Previous studies examined two categories of technologies that potentially enable HCA in outage control: 1) computational modeling and simulation methods for predicting states of field operations and workflows; 2) data collection and processing methods for capturing the reality and thus providing feedback to computational models. Unfortunately, limited studies systematically synthesize technological challenges related to these practical problems and underlying HCA principles. This paper identifies the domain requirements, challenges, and potential solutions of achieving the HCA system that effectively supports resilient NPP outage control. This proposed system aims at significantly improving the performance of handoff monitoring/control and responding to contingencies during the outage. Firstly, the authors identified information acquisition and modeling challenges of achieving human-center automation for outage control. The rest of the paper then synthesizes potential techniques available in the domains of computer science, cognitive science, system science, and construction engineering that can potentially address these challenges. The authors concluded this literature and technological review with a research roadmap for achieving HCA in construction.

Handoff Performance Improvements in an Integrated Train-Ground Communication System Based on Wireless Network Virtualization

In existing urban rail transit systems, the train-ground communication system for different subsystems is deployed independently. Investing and constructing the communication infrastructures repeatedly not only wastes substantial social resources, but it also is difficult to maintain all these infrastructures. In this paper, we propose an integrated train-ground communication system based on wireless network virtualization for urban rail transit systems. In order to improve the communication-based train control (CBTC) subsystem performance during handoff, we propose a novel handoff scheme to support handoff between virtual networks. The application-layer quality-of-service (QoS) parameters of the CBTC, passenger information system, and closed circuit television subsystems are used as the performance measures in the handoff design. We then formulate the QoS optimization problem in the proposed integrated train-ground communication system as an approximate dynamic programming (ADP) problem. The extensive simulation results show that the proposed integrated train-ground communication system QoS can be improved substantially with our ADP-based optimization model.

Design and Performance Evaluation of an Enhanced Handover Scheme in Hierarchical Mobile IPv6 Networks

Mobile communication is increasingly oriented towards the usage of all IP networks as fixed network components. The handover performance of mobile IPv6 is one of the key factors which guarantee the QoS of mobile Internet. In this paper, an enhance handover scheme in hierarchical MIPv6 networks by utilizing Passive Duplicate Address Detection (PDAD) to identify duplicate addresses is proposed. Using PDAD, a node examines incoming routing protocol packets to develop hints about address controversies. The simulations are performed using NS-2 to compare the handoff performance. The results show that the proposed scheme can get better performance in terms of packet loss and handoff delay.

Critical Access Hospital Use of TeamSTEPPS to Implement Shift-Change Handoff Communication.

Implementation of handoff as part of TeamSTEPPS initiatives for improving shift-change communication is examined via qualitative analysis of on-site interviews and process observations in 8 critical access hospitals. Comparing implementation attributes and handoff performance across hospitals shows that the purpose of implementation did not differentiate between high and low performance, but facilitators and barriers did. Staff involvement and being part of the "big picture" were important facilitators to change management and buy-in.