Ongoing Sessions Research Articles

Resilient overlay network for real-time interactive multimedia sessions in corporate networks

Real-time interactive multimedia communications are becoming increasingly useful for education, business, e-commerce and e-government, providing an enriched user experience in teleconferencing, e-meetings, distance training and product demonstrations. Large corporations are usually located at several sites, so real-time multipoint sessions within corporations are especially difficult. IP multicast is available or feasible within each site of an organization. Thus, corporate networks can be considered as various multicast-capable networks interconnected through a wide area network without multicast connectivity. This paper proposes a resilient self-managed overlay network to support real-time multipoint interactive sessions within corporate networks. The proposed overlay takes advantage of the configuration of corporate networks to self-organize and provide an efficient media delivery service, making use of multicast communications wherever available. Various self-healing techniques are implemented allowing for the continuity of ongoing sessions in spite of network disruptions and entity failures. Extensive simulations and tests have been carried out to assess the performance and resilience of the overlay facing several types of disruptions.

EPD-NEMO: efficient PMIPv6-based distributed network mobility management

Current network mobility management protocols allow users to access broadband Internet while moving in vehicles or from vehicles to fixed locations without breaking ongoing sessions. These protocols rely on a central mobility anchor such as home agent or local mobility anchor. Thus, some issues, including a single point of failure, long handover delay, and scalability, are exposed in these existing approaches. Ever-increasing demand for mobile Internet traffic changes the mobile network from a hierarchical architecture to a flat architecture and distributed schemes are being researched for the purpose of adapting to new flat architecture and overcoming the aforementioned issues. In this paper, we do a survey of existing network mobility management protocols, current solutions for distributed mobility management, and present an efficient PMIPv6-based distributed network mobility management scheme. The proposed scheme consists of characteristics of distributed mobility management and a new handover mechanism to reduce the packet delivery overhead while keeping seamless Internet access to users in vehicles. By numerical analysis, we prove that our new approach improves service disruption time and packet delivery cost compared to exiting solutions under various environment conditions.

HSCT Education: Bridging the Gap

Topic Significance & Study Purpose/Background/ Rationale: In 2014 the HSCT program at the academic medical center became a member of the NMDP. This brought the challenge of ensuring that those whowould be trusted to care for these patients have the proper knowledge and skill base to be successful. A review of strategies was undertaken to effectively meet the educational needs of staff caring for HSCT patients across settings. Methods, Intervention, & Analysis: The leadership team, in conjunction with the HSCT staff, identified an opportunity to enhance knowledge among staff nurses in both the inpatient and ambulatory care setting. The goal: prepare staff to care for this complex patient population and to improve relationships between inpatient and ambulatory nurses and to enhance continuity of care. A multi-disciplinary education plan was created involving various venues and formats to address these goals. Initially a multi-day intensive educational offering was provided in collaboration with an external expert. These sessions covered topics from diseases treated by HSCT, indications for each type of transplant, and the basics of HLA typing. Internal experts including nurses and pharmacists offered additional sessions, focusing on care of the allogeneic transplant patient. An HSCT physician offers informal bi-weekly sessions that address just-in-time clinical issues. Finally in an effort to support staff preparing for the bone marrow transplant certified nurse exam (BMTCN) a study group is offered on a monthly basis. Findings & Interpretation: Approximately 75% of staff have attended the sessions with ongoing session being offered to meet the needs of new staff and those who did not participate in the initial sessions. Feedback from staff has been positive: “These sessions were great” and “It was really neat to meet the outpatient nurses.” Discussion & Implications: In addition to increasing knowledge and confidence of nurses, this program has increased communication and cohesiveness among the nursing staff. This program will be continued and expanded to meet the needs of nurses throughout the organization caring for HSCT patients.

Context-aware adaptive IP mobility anchoring

The novel distributed mobility management trend is a promising direction to cope with the increasing mobile data traffic and flatten network architectures. Most of the novel mobility approaches distribute the mobility anchors through the access level, as opposed to the centralized mobility anchoring model. Other recent approaches argue that mobility anchors closer to the content servers may be the solution to optimize the mobility performance. However, none of the mobility anchoring models is ideal for all scenarios, since it depends on the user, the session and the network. Hence, we propose an IP mobility approach driven by the context of the user, sessions and the network, where the mobility anchors for IP address allocation and for routing/forwarding are distributed through the network nodes, while the mobility context is managed by the mobile devices. Although each session is properly anchored in the establishment phase, the routing/forwarding is adapted over time, according to the user, the session and the network context: the proposed approach is able to signal different mobility anchors to optimize the routing path to new and ongoing sessions of the user. The outcome of the evaluation shows that the proposed approach overall reduces the data cost, the data delay, the tunneled packets and the tunnel length, when compared with other anchoring models.

Reducing handoff delay by adaptive threshold tuning and location updates in mobile WiMAX

In wireless networks data are sent and received with impressive speed and ease. Mobile WiMAX is a broadband wireless solution that enables coverage of mobile and fixed broadband networks with flexible network architecture. Devised as a truly broadband access solution, the WiMAX technology offers promising features in terms of high bandwidth, extended coverage area and low cost. Despite having many advantages, WiMAX faces major research issues like QoS based bandwidth a llocation, Roaming, Internetworking with other technologies, security and handoff. Handoff occurs when a mobile user goes from one cell to another without interruption of ongoing session. Many approaches have been proposed for reducing handoff delay. In this paper, we propose a new approach by which a critical area, an area far away from serving base station but still inside the coverage of serving base station, is found. And then overlapping area between serving base stations and neighboring base station a re found and tabulated. According to the size of overlapping area, different weights are assigned where handoff threshold is changed adaptively to reduce handoff delay.

Network selection algorithm based on link quality parameters for heterogeneous wireless networks

Abstract Next generation wireless networks consist of heterogeneous access technologies. In order to provide global ubiquitous communication, it is required to provide a framework in which user can move across multiple access interfaces while maintaining its ongoing communication at perceived quality of service. Given the scenario of multiple access networks, it is further required to select the optimum network out of multiple candidate networks to meet the requirements of the ongoing session. The selection of optimum network in such heterogeneous environment is generally based on network conditions and user preference. In this paper, we propose an algorithm for network selection based on averaged received signal strength, outage probability and distance. The proposed algorithm comprises of two stages. Assuming that network conditions are dominant in network selection, in first stage, overlapping region is identified through distance estimation. Network selection algorithm based on averaged received signal strength plus outage is invoked in second stage to select the optimum network. Numerical results are obtained through a simulation model of two disparate networks – GSM and UMTS. It has been shown that the proposed algorithm offers 68% improved performance in terms of network selection rate.

Network based Load-Aware Mobility Management in IEEE 802.11 Wireless Mesh Networks

One major concern for mobile networks consists of finding efficient way s of handling user mobility so that the handover process has minimum effect on users' ongoing sessions. Although COAP provides an efficient way for mobility management in IEEE 802.11 wireless mesh networks, it does not control load among multiple MAPs in the network. Thus, in many cases, the attached MAP is overloaded, and extensive delays are experienced during the routing process. To tackle this problem, this paper proposes a load-aware mobility management scheme. The overloaded MAP is detected according to the load estimation. Then the overloaded MAP initiates the search procedure to find the underutilized MAP and transfe r the MN's attachment request to it. The proposed scheme can efficiently balance the handover load among MAPs at the cost of sligh tly prolonged attachment delay and increased attachment messages compared with COAP.

Design and analysis of secure host-based mobility protocol for wireless heterogeneous networks

Mobility protocols allow hosts to change their location or network interface while maintaining ongoing sessions. While such protocols can facilitate vertical mobility in a cost-efficient and access agnostic manner, they are not sufficient to address all security issues when used in scenarios requiring local mobility management. In this paper, we propose a new scheme that makes Host Identity Protocol (HIP) able to serve as an efficient and secure mobility protocol for wireless heterogeneous networks while preserving all the advantages of the base HIP functions as well. Our proposal, called Heterogeneous Mobility HIP (HMHIP), is based on hierarchical topology of rendezvous Servers (RVSs), signaling delegation, and inter-RVS communication to enable secure and efficient network mobility support in the HIP layer. Formal security analysis using the AVISPA tool and performance evaluation of this method are provided; they confirm the safety and efficiency of the proposed solution. HMHIP reduces handover latency and packet overhead during handovers by achieving registration locally.

Evaluating context-aware user interface migration in multi-device environments

People access applications and services through different devices depending on location and needs. During a single day, people can use a smartphone, tablet, PC and a TV, sequentially or simultaneously, depending on the context of use. Even within a single task, people often start with one device, such as a smartphone, and continue with another device, such as a PC, as the task evolves. To provide fluent task continuation, the system should provide ways to migrate on-going sessions from one device to another in a seamless manner. In this paper, we present a solution for migrating user interface and maintaining the interaction session across devices when changing situations. With two studies we gain insights into user needs and technical requirements for context-aware information sharing in multi-device environments. A longitudinal diary study was conducted to uncover specific situations where users have needs for information sharing, and how they would prefer the system to react in those situations. We also conducted a controlled user study using a prototype system for session migration between devices in changing contexts, with three different operational modes: manual, assisted and automatic, to gain a deeper knowledge into the requirements. The findings indicate a need for easier interaction whilst switching between devices and that these needs are often situation-specific. We also report in detail how people would prefer the system to perform migrations automatically and intelligently suggest them in some situations. Moreover, we draw technical requirements for such a system in order to develop seamless context-aware migration.

A Multihop-Authenticated Proxy Mobile IP Scheme for Asymmetric VANETs

Vehicular communications networks are envisioned for the access to drive-thru Internet and IP-based infotainment applications. These services are supported by roadside access routers (ARs) that connect vehicular ad hoc networks (VANETs) to external IP networks. However, VANETs suffer from asymmetric links due to variable transmission ranges caused by mobility, obstacles, and dissimilar transmission power, which make it difficult to maintain the bidirectional connections and to provide the IP mobility required by most IP applications. Moreover, vehicular mobility results in short-lived connections to the AR, affecting the availability of IP services in VANETs. In this paper, we study the secure and timely handover of IP services in an asymmetric VANET and propose a multihop-authenticated Proxy Mobile IP (MA-PMIP) scheme. MA-PMIP provides an enhanced IP mobility scheme over infrastructure-to-vehicle-to-vehicle (I2V2V) communications that uses location and road traffic information. The MA-PMIP also reacts, depending on the bidirectionality of links, to improve availability of IP services. Moreover, our scheme ensures that the handover signaling is authenticated when V2V paths are employed to reach the infrastructure so that possible attacks are mitigated without affecting the performance of the ongoing sessions. Both analysis and extensive simulations in OMNeT++ are conducted, and the results demonstrate that the MA-PMIP improves service availability and provides secure seamless access to IP applications in asymmetric VANETs.

Joint Time and Spatial Reuse Handshake Protocol for Underwater Acoustic Communication Networks

In most existing handshake-based collision avoidance (CA) protocols, nodes in the communication range of the transmitter or the receiver are kept silent during an ongoing communication session (CS). In underwater acoustic communication (UWAC), this restriction results in low throughput and long transmission delay. In this paper, we utilize the long propagation delay in the underwater acoustic channel and the (possible) sparsity of the network topology, and formalize conditions for which a node can transmit even when it is located within the communication range of a node participating in a CS. We consider these conditions as design constraints and present a distributed CA handshake-based protocol, which, by jointly applying spatial and time reuse techniques, greatly improves channel utilization. Our simulation results show that our protocol outperforms existing handshake-based protocols in terms of throughput and transmission delay. These gains come at the price of some reduction in fairness in resource allocation.

Two-Tier CHORD for Decentralized Location Management

To conceive the full potential of ubiquitous mobile computing, mobile nodes must be able to roam seamlessly across different networks. However, the location i.e. IP address, of a called mobile nodes must be determined within a certain amount of time, before the services are blocked. With the upcoming 3G, 4G and wireless LAN technologies, it is necessary to have an efficient location management system that adapts to such dynamic environments, and augment problems like center point of failure, delay and lack of reliability. One approach is to provide decentralized location management, using CHORD, whose key vale mapping can efficiently determine the required name to IP mapping. However, a major issue concerning this technique is the presence of unstable chord nodes, which brings instability to the framework. Nodes with minimum computation capabilities can slow down the lookup mechanism, and hence terminates the ongoing session. This paper provides a solution to this problems using well-known two-tier CHORD architecture. Nodes with high computation power and stability will act as Location Servers, which will be responsible for storing and distributing temporary locators i.e. IP addresses of the called mobile node. Suitability of the proposed framework is tested using analytical analysis in comparison with the existing chord mobility framework. Such an approach can bring stability to the framework, with its decentralization feature still intact.

Training and maintaining motivational interviewing skills in a clinical trial

Motivational interviewing (MI) is an evidence-based practice that is being implemented in a wide range of settings. Research supports the importance of ongoing coaching and feedback sessions following initial training in MI to implement and sustain MI-adherent competencies. This article describes the development and preliminary testing of a group feedback and consultation process where clinicians code each others’ clinical samples of MI sessions and provide feedback to each other regarding the level of adherence to MI fidelity measures. Preliminary results suggest that group feedback may help clinicians develop and sustain MI skills.

Analysis of Ongoing SIP Session with Resource Reservation in Vertical Handover Scenario

Typically, WiFi-to-3G handover is time-critical depending on mobility and speed of mobile host (MH) while 3G-to-WiFi handover is optional for better quality of service and less cost. In this paper,...

Architectural framework for mobile multicast support in wireless mesh networks

A wireless mesh network (WMN) is an infrastructure multihop ad hoc network with broadband capabilities. Multicasting is an efficient mechanism for delivery of group communication. However, the current IEEE 802.11s standard has no provision for efficient group communication delivery. Furthermore, the disruption in internet connectivity and loss of information when a mobile mesh client changes its point of attachment may lead to disruption in an ongoing session. The internet gateway (IGW), a prominent component, serves as the wired bridge between the mesh nodes and the internet, thus its placement determines the overall quality of communication in WMNs. Accordingly, a structural design for supporting multicast services in this architecture is indispensable. The main question this paper addresses is how multicast can be efficiently supported for mobile mesh clients in WMN architecture. This paper adopts the technique of employing multicast architecture to solve mobility problems for mobile mesh clients. Thus a framework of novel architecture for supporting multicast services for group application delivery over WMN is presented. The proposed architecture features enhanced functionality of IGW, shared multicast tree, optimal design for IGW and core placement, hierarchical mobility management, load balancing, and robustness. The overall objective is the provision of cost efficient WMN architecture while mobile multicast traffic delivery is supported optimally. This is the first effort reporting multicast service support framework for mobile mesh clients with a focus on IGW placement and functionality.

Local Mobility Management for Networked Femtocells Based on X2 Traffic Forwarding

The femtocell is becoming a promising solution to face the explosive growth of mobile broadband usage in cellular networks. Although each femtocell only covers a small area, a massive deployment is expected to form networked femtocells in the near future. One immediate challenge is to provide seamless mobility support for networked femtocells with minimal support from mobile core networks. In this paper, we propose efficient local mobility management schemes for networked femtocells based on X2 traffic forwarding under the Third-Generation Partnership Project Long-Term Evolution Advanced (3GPP LTE-A) framework. Instead of implementing the path switch operation at core network entity for each handover, a local traffic forwarding chain is constructed to use the existing Internet backhaul and the local path between the local anchor femtocell and the target femtocell for ongoing session communications. Both analytical studies and simulation experiments are conducted to evaluate the proposed schemes and compare them with the original 3GPP scheme. The results indicate that the proposed schemes can significantly reduce the signaling cost and relieve the processing burden of mobile core networks with the reasonable distributed cost for local traffic forwarding. In addition, the proposed schemes can enable fast session recovery to adapt to the self-deployment nature of the femtocells.

Secured Identity Based Approach With Privacy Preservation For Wireless Mesh Networks

Wireless Mesh Networks WMNs have been expected to be the ultimate solution for the next decade wireless networking. The attractions of WMNs include easy set-up on the fly, off-the-shelf cost, flexible interoperability with other networks, and highly reliable connectivity. One main challenge in the design of these networks is their vulnerability to security attacks. The attacker will possibly be able to identify an ongoing communication session between any two network users by analyzing the network traffic pattern without knowing the users identity information. To address these security risks, Secured routing scheme that preserves the privacy of end users is proposed using Secured Identity Based Approach SIBA in which every nodes are assigned with the Security cards for efficient authentication. The major goal of the proposed system is to reduce the number of attacker level by providing anonymity in routing.

Proactive QoS Enhancement Technique for Efficient VoIP Performance over Wireless LAN and Cognitive Radio Network

VoIP over Wireless LANs is greatly affected bypath-loss, RF interference and other sources of signalattenuation in addition to network congestion. The primaryfactors involved in effective real-time communication,namely delay and loss, must be within certain controlledlimits in such a scenario. Wireless LAN Access Points must,therefore, act in tune with the codecs to ensure high qualityof the ongoing VoIP sessions. Further deployment of VoIPin opportunistic communication medium like cognitiveradio network requires thorough analysis of the factorsinvolved in design and implementation of such networksalong with modifications in VoIP parameters. In this paper,the various codec parameters are analyzed with respect towireless LAN access points. Thereafter, an optimizationalgorithm is developed based on proactive strategy to keeploss and latency within tolerable limits. The proposedalgorithm is hence implemented in the SIP enabled test-bedto provide optimum Voice over IP (VoIP) performance. Theproactive strategy is further applied to study VoIPperformance over cognitive radio networks. A simulationmodel is developed for VoIP transmission in cognitive radionetworks with two scenarios where the primary and thesecondary user involve in VoIP transmission respectively.For each scenario, extensive analysis of both VoIP and CRNparameters is performed and an algorithm is proposedbased on codecs and active queues to ensure highthroughput of VoIP traffic with enhanced QoS. Resultsverify significant performance improvement in VoIP callquality under both wireless LAN and cognitive radionetwork environment. Simulation and measured resultshave also been included.

Investigating Students' Perceived Discipline Relevance Subsequent to Playing Educational Computer Games: A Personal Interest and Self-Determination Theory Approach

The purpose of this study is to explain students' perceived relevance of playing an educational game as a means for development of discipline competence. Based on self-determination theory and the concept of personal interest, we propose that: Satisfying students' basic needs for competence, autonomy, and relatedness when playing educational games is critical for arousal of intrinsic motivation in learning-through-gaming; Students' interest in the core subject and their intrinsic motivation in learning-through-gaming are important for their perceptions of how relevant they believe the gaming session is for the discipline they are studying. The results from an empirical study indicate that arousal of intrinsic motivation in the ongoing gaming session is more important than pre-gaming interest in the core subject for participants' post-gaming perception of how relevant such gaming is as a means for developing their discipline competence. The results also indicate that satisfying basic needs for competence, autonomy, and relatedness is critical for arousal of intrinsic gaming motivation. Our findings have implications for the choice of pedagogical means when utilizing educational games as a complementary alternative to traditional learning methods. To that end, we offer directions for future research.

Cost and Efficiency Analysis of NEMO Protocol Entities

To support IP-mobility of networks in motion, IETF proposed Network Mobility (NEMO) protocol that uses various signaling messages to ensure connectivity of the mobile nodes with the Internet and to maintain security of ongoing sessions by protecting the binding updates. As the next-generation wireless and mobile network is supposed to be a unified network based on all-IP technology, compounded by the fact that the number of mobile nodes requiring mobility support has increased significantly, the cost analysis of mobility protocols and the underlying mobility management entities have become essential to avoid their performance degradation. However, there has been no comprehensive cost analysis of NEMO protocol entities that considers all possible costs. In this paper, we have developed analytical models to estimate total costs of key mobility management entities of NEMO. We have defined a metric to compute the efficiency of mobility protocol as well as the mobility entities to find out the percentage of resources used for data (payload) delivery. We have presented numerical results to demonstrate the impact of network size, mobility rate, traffic rate and data volume on the total costs and the efficiency of the NEMO protocol and its key entities. Our results show that a significant amount of resources (bandwidth, processing power, transmission power) are required by the mobility entities for transmission, processing of various signaling messages, as well as searching location database. Our cost analysis will thus help network engineers in estimating actual resource requirements for the key entities of the network in future design while analyzing the data transmission efficiencies of these entities.