Wireless Network Infrastructure Research Articles

Implementation Issues of Virtual Desktop Infrastructure and Its Case Study for a Physician's Round at Seoul National University Bundang Hospital

ObjectivesThe cloud computing-based virtual desktop infrastructure (VDI) allows access to computing environments with no limitations in terms of time or place such that it can permit the rapid establishment of a mobile hospital environment. The objective of this study was to investigate the empirical issues to be considered when establishing a virtual mobile environment using VDI technology in a hospital setting and to examine the utility of the technology with an Apple iPad during a physician's rounds as a case study.MethodsEmpirical implementation issues were derived from a 910-bed tertiary national university hospital that recently launched a VDI system. During the physicians' rounds, we surveyed patient satisfaction levels with the VDI-based mobile consultation service with the iPad and the relationship between these levels of satisfaction and hospital revisits, hospital recommendations, and the hospital brand image. Thirty-five inpatients (including their next-of-kin) and seven physicians participated in the survey.ResultsImplementation issues pertaining to the VDI system arose with regard to the highly availability system architecture, wireless network infrastructure, and screen resolution of the system. Other issues were related to privacy and security, mobile device management, and user education. When the system was used in rounds, patients and their next-of-kin expressed high satisfaction levels, and a positive relationship was noted as regards patients' decisions to revisit the hospital and whether the use of the VDI system improved the brand image of the hospital.ConclusionsMobile hospital environments have the potential to benefit both physicians and patients. The issues related to the implementation of VDI system discussed here should be examined in advance for its successful adoption and implementation.

Mobility management for multimedia services in heterogeneous environments

Nowadays, the wireless access network infrastructure is growing at an accelerated pace. In the current environment which consists of a multitude of wireless networks, live migration of multimedia streaming between different types of connectivity offers important advantages for mobile users. In this paper we provide the description of efficient mobility service architecture for multimedia environments. The proposed architecture handles multimedia streaming adaptation, session management, and takes into consideration user profiles and a set of quality of service criteria. Session management in a mobile environment also implies that a handover mechanism must be used in order to ensure session continuity when a user moves from one network to another. Our architecture supports handover at the application layer, which offers a better quality control than the majority of mobility solutions. In order to demonstrate the performance of our mobility solution, we analyse results from different test scenarios.

A Game-Theoretic Perspective on Code Synchronization for CDMA Wireless Systems

This paper introduces a game-theoretic formulation for the problem of resource allocation in an infrastructure CDMA wireless communication network, focusing on the issue of initial code synchronization. To capture the tradeoff between obtaining good synchronization performance and saving as much energy as possible, we propose a noncooperative game in which each transmitter-receiver pair seeks to maximize the ratio of the probability of code alignment detection to the transmitted energy per acquisition, under a constraint on the maximum probability of spurious code locks - this is achieved by properly setting the receiver threshold and the transmit power. Our framework also considers the coexistence between different types of synchronizers and different QoS requirements. The generalized Nash solution of the game is investigated and closed-form expressions are derived and compared with simulation results for an iterative decentralized algorithm.

기업용 모바일 클라우드 시스템 구축 시 고려 요인

Recently, various mobile services are provided by the spread of wireless network infrastructures and smart devices. The improvement of cloud computing technologies increases the interests for enterprise mobile cloud services in various IT companies as well. By increasing the interests for enterprise mobile cloud services, it is necessary to evaluate the use of enterprise mobile cloud services. Therefore, the factors which affect the user acceptance of enterprise mobile cloud services are analyzed on the basis of Davis` technology acceptance model in this research. As analysis results, four external variables have significant effects on perceived ease of use of mobile cloud services. Also, these variables indirectly affect attitude toward using cloud services. The results show that the security is the most important factor for attitude toward using enterprise mobile cloud services. The service users also consider the interoperability as an important factor for the user acceptance of cloud services. The perceived ease of use has more contribution than the perceive usefulness on attitude toward using enterprise mobile cloud services. This research has both industrial and academic contributions because it provides the guideline to companies for introducing the enterprise mobile cloud services and apply the technology acceptance model on new IT services.

Utilizing a Test Lab For Wireless Medical Devices

Changes in healthcare suggest that more and more medical devices will begin to utilize the information technology (IT) network infrastructure in the hospital, particularly the wireless network. Due to the increased risk of operating medical devices on the converged wireless IT network, there are multiple steps required to safely and effectively implement these types of devices. A key component of the implementation should be to perform testing of wireless devices for interference and functionality. In order to perform this testing, development of a test environment within the hospital is required. While recent focus has been on electromagnetic interference and the risk assessment and mitigation via IEC 80001-1— the new standard for the application of risk management for IT networks incorporating medical devices—more progress is needed in the development of a test lab and performance of testing within the hospital environment. There are many potential benefits of deploying medical devices on the wireless network; however, there are multiple risks, including loss of data or missed patient alarm notification due to a loss of wireless network connectivity. Testing can be vital in identifying and developing mitigations for these risks. Creating the Lab In order to create a test lab, a location first must be selected. In theory, an ideal wireless test environment would be shielded from all external sources of radio frequency (RF) interference. To achieve this goal, physical space and a substantial budget would be required. A stand-alone wireless network infrastructure would have to be developed in this shielded space to enable the connection and testing of any wireless medical devices. This type of test environment is impractical for clinical engineering use due to resource constraints and the inadequacy for realistic simulation of the true deployment environment. A more realistic and beneficial location to create the test lab would be a clinical engineering shop or a storage area in the basement of the hospital. The value of this type of location is that the physical space is relatively distant from clinical floors, thereby limiting the interference between the current patient-care equipment and the test lab and reducing the potential risk to either the device under test or to the devices on the clinical floor. It is also advantageous to be in the hospital in order to utilize a segregated portion of the network infrastructure that is already in place. Also, although a test lab in this environment would not be totally isolated About the Author

Power Control Methods for Improving Spatial Reuse in TDMA-Based Wireless Mesh Networks

Wireless Mesh Networks (WMNs) have attracted a great deal of interest in recent years as a cost-effective method to provide a wireless network infrastructure. To accommodate various types of application traffic in WMNs, improvement of network capacity is one of the most critical issues. The efficiency of wireless network resource utilization decreases due to radio interference when multiple transmissions occur simultaneously in an interference region. To resolve this problem, we focus on the transmission power control of mesh nodes. We expect to improve spatial reuse by applying power control because this decreases radio interference between wireless links. In this paper, we propose power control methods of mesh nodes for improving spatial reuse in TDMA-based wireless mesh networks. We first propose two types of power control methods, which employ a simple threshold-based mechanism. Furthermore, we develop an additional method that suppresses the unnecessary increase in path length associated with limiting the increase in the hop count to the nearby mesh nodes. Numerical evaluation results reveal that the proposed method decreases the frame length by up to 27% with non sensitive parameter setting.

Agent-Based Optimization for Large Scale WLAN Design

The complex nature of wireless local area networks (WLAN) design has led many of the deployments being done in an ad-hoc fashion without efficient design methodologies. Although this approach may work for a small environment with a small number of access points, it is infeasible to use such a process when designing a larger wireless infrastructure. Due to the low cost that is indicative of WLAN deployments, many practitioners view formal optimization techniques as being too complex and costly to implement. There have been a number of research works that investigate the use of formal optimization techniques for the accurate design of a WLAN. Unfortunately, the approaches taken do not address one major issue when designing a complex and demanding wireless network infrastructure, namely scalability. An optimization algorithm must consider a multitude of design criteria and therefore needs to be scalable to be successfully applied to large scenarios. The main contribution of the work presented in this paper is the development of a scalable optimization algorithm based on the tools of distributed artificial intelligence, which overcomes the failings of current approaches and can be utilized for WLAN design regardless of size or complexity of site specific requirements.

Throughput and delay analysis of multi-channel wireless infrastructure networks

Wireless infrastructure networks (WINs) provide ubiquitous connectivity to mobile nodes in metro areas. The nodes in such backbone networks are often equipped with multiple transceivers to allow for concurrent transmissions in multiple orthogonal channels. In this study, we develop an analytical model for the estimation of the delay and throughput performance of wireless infrastructure networks employing slotted ALOHA channel access and slotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) over multiple channels. The analytical model, which takes into account the correlation due to multi-hop transmissions, approximates the performance observed through simulations accurately.

Doubly Cognitive Architecture Based Cognitive Wireless Sensor Networks

Scarcity of spectrum is increasing not only in cellular communication but also in wireless sensor networks. Adding cognition to the existing wireless sensor network (WSN) infrastructure has helped. As sensor nodes in WSN are limited with constraints like power, efforts are required to increase the lifetime and other performance measures of the network. In this article, the authors propose Doubly Cognitive WSN, which works by progressively allocating the sensing resources only to the most promising areas of the spectrum and is based on pattern analysis and learning. As the load of sensing resource is reduced significantly, this approach saves the energy of the nodes and reduces the sensing time dramatically. The proposed method can be enhanced by periodic pattern analysis to review the strategy of sensing. Finally the ongoing research work and contribution on cognitive wireless sensor networks in Communication Research Centre (IIIT-H) is discussed.

Hybrid Wireless Networks for E-Learning and Digital Literacy

Today, satellite communication networks are being integrated into the infrastructure of modern Terrestrial communication networks and becoming popular for the delivery of educational content and data, as well as education-centric services, including information, tele-conferencing, entertainment, or ‘edutainment’ services. With fresh demand for new services and applications, it is becoming essential that wireless network architecture seamlessly interoperate with new and existing technologies, protocols and standards. This paper presents recent work on the use of hybrid wireless network infrastructures for delivering tele-education and e-learning applications to remote communities by combining a variety of satellite, terrestrial and wireless technologies, and provides the results from live scenarios carried out employing various methods of interoperability testing. The analysis of the results examines a number of different issues such as delay, jitter, packet loss, latency, throughput measurement, and bandwidth. By combining satellite and terrestrial (wireless) technologies, full coverage and high capacity can be achieved for true broadband services for delivering educational content. The interoperability among such diverse networks imposes a number of challenges regarding service provision and management.

Study on the Application of Small-Size Wireless Network in Modern Model of Education

Since the 21st century, the rapid development of computer network technology has driven the new changes of all industries, of which institutes of higher education are the first to be affected, and a new revolution of methods of teaching and model of teaching has been started, namely, the wide application of modern educational technology. However, the new type model of teaching has suffered certain restrictions in the process of spread and exploitation due to the limitation of network access, and has not been fully utilized, which causes an unsatisfactory teaching effect. The expansion of network cabling requires a certain degree of economic strength, which is just generally deficient in all institutes of higher education. If depending on the wireless network infrastructure, we can connect variety of modern educational methods and network together under the premise of low cost investment so as to give full play to their important roles in teaching and create new mode of teaching for all institutes of higher education.

Study on the Application of Small-Size Wireless Network Infrastructure in the Reform of Modern Means of Education

With the continuous development of Internet technology, the modern means of education based on computer network technology have been enriched constantly, and are unconsciously influencing the traditional classroom model of teaching, and have achieved very significant achievements in practical teaching. However, due to network access restrictions, all kinds of modern means of education have been greatly limited in the application process, and the popularizing rate is difficult to be increased, so that the teaching effect is not very satisfactory. If depending on the wireless network, we can connect variety of modern educational methods and network together under the premise of low cost investment so as to give full play to their important roles in teaching.

Maximum bipartite flow in networks with adaptive channel width

Traditionally, network optimization problems assume that each link in the network has a fixed capacity. Recent research in wireless networking has shown that it is possible to design networks where the capacity of the links can be changed adaptively to suit the needs of specific applications. In particular, one gets a choice of having a few high capacity outgoing links or many low capacity ones at any node of the network. This motivates us to have a re-look at classical network optimization problems and design algorithms to solve them in this new framework. In particular, we consider the problem of maximum bipartite flow, which has been studied extensively in the fixed-capacity network model. One of the motivations for studying this problem arises from the need to maximize the throughput of an infrastructure wireless network comprising base-stations (one set of vertices in the bipartition) and clients (the other set of vertices in the bipartition). We show that this problem has a significantly different combinatorial structure in this new network model from the fixed-capacity one. While there are several polynomial time algorithms for the maximum bipartite flow problem in traditional networks, we show that the problem is NP-hard in the new model. In fact, our proof extends to showing that the problem is APX-hard. We complement our lower bound by giving two algorithms for solving the problem approximately. The first algorithm is deterministic and achieves an approximation factor of O ( log N ) , where N is the number of nodes in the network, while the second algorithm is randomized and achieves an approximation factor of e e − 1 .

A pervasive assistive environment for visually impaired people using wireless sensor network infrastructure

Wireless sensor networks (WSNs) have been identified as a promising technology for supporting assistive environments. This article introduces PROTECT, a system that employs autonomous software objects referred to as mobile agents (MAs) able of locating and informing visually impaired persons for potential risks. PROTECT utilizes a 3-tier architecture where the first tier comprises a base station (BS), the second tier mobile sinks (MS) (carried by blind people on their sticks) and the third tier stationary sensor nodes. This WSN is deployed in an urban environment. In the event of an alarm issued by a sensor node, the BS launches a number of MAs supplied with a near-optimal itineraries that visit the nodes in the alarm's surrounding area and notifies, through Wi-Fi (IEEE 802.11), visually impaired people for potential hazards in their proximity. In the event of communication problems (e.g. failure of some sensor nodes) PROTECT modifies the itineraries of the MAs to bypass the problematic areas avoiding disruption of the data collection process from working sensors. Simulation results confirm the high effectiveness of our proposed scheme in WSNs used in assistive environments and its performance gain over alternative MA-based approaches proposed for data fusion tasks.

Robust indoor positioning using differential wi-fi access points

Location positioning systems using wireless area local network (WLAN) infrastructure are considered cost effective and practical solutions for indoor location tracking and estimation. However, accuracy deterioration due to environmental factors and the need for manual offline calibration limit the application of these systems. In this paper, a new method based on differential operation access points is proposed to eliminate the adverse effects of environmental factors on location estimation. The proposed method is developed based on the operation of conventional differential amplifiers where noise and interference are eliminated through a differential operation. A pair of properly positioned access points is used as a differential node to eliminate the undesired effects of environmental factors. As a result the strength of received signals, which is used to determine the location of a user, remains relatively stable and supports accurate positioning. To estimate wave propagation in indoor environments, log-distance path loss model has been employed at the system level. Experimental results indicate that the proposed method can effectively reduce the location estimation error and provide accuracy improvement over existing methods.

Tracing Anonymous Mobile Attackers in Wireless Network

In a flooding-based distributed denial-of-service (DDoS) attack, an adversary attempts to exhaust a target’s computing resource. To detect DDoS attacks in a network environment, IP traceback methods are deployed to determine the origin of attack packets. With the increase in bandwidth of wireless networks, attackers may choose this medium from which to launch attacks. However, tracing the attackers in wireless networks is more difficult since intermediate nodes may move or attackers may change their location to hide themselves. Thus, conventional traceback schemes for wired networks cannot apply directly to the wireless network infrastructure because the intermediate routers could be compromised by an adversary. Therefore, we propose a flexible and lightweight traceback scheme to determine the source of attack packets in a mobile ad-hoc environment. We will demonstrate our method’s ability to track the movement of an attacker and recognize attack traffic launched by the same attacker from different locations.

Communications of the IBIMA

Cost efficiency has been a dominant perspective in the traditional IT literature. However, in complex technology and business environment, the widely recognized cost efficient assumption of information technology has been increasingly challenged. Drawing from a case study of wireless network implementation situated in a politically sensitive workplace, this paper provided practice insights for IT managers in today’s networked economy. More specifically, stories experienced in the case study illustrated that despite well-calculated cost efficiency of wireless network infrastructure, the radical implementation process in the case organization encountered enormous challenges and opposition due to the fact that administrators failed to consider various stakeholders’ positions and interests. Eventually, the implementation objectives and outcome were considerably undermined. Implications from this empirical case research reemphasized the significance of understanding political forces situated in any business environment where different stakeholders hold conflicting interests. Lessons learned from the case story further encouraged IT managers and policy makers to better strategize emerging information technology in general and wireless networks in particular as the whole global society and business environment are increasingly facing an emerging wireless world.

A Rendezvous-Location Based Multicast Secure Communication in Ad Hoc Networks

Mobile ad-hoc networking (MANET) is a collection of mobile nodes that want to communicate to each others, but has no fixed links like wireless infrastructure networks to provide group applications and services. Therefore we need concern about providing each node with a secure and efficient key management system for dynamically discovering other nodes which can directly communicate with. Due to the network topology of an ad hoc network changes frequently and unpredictable, so the security of multicast routing becomes more challenging than the traditional networks. In this paper, we describe how any users in the multicast group can compose the group keys and propose a hierarchical group key management to securely multicast data from the multicast source to the rest of the multicast members in wireless ad hoc networks. This approach has a hierarchical structure where the group members are partitioned into rendezvous-location based clusters which can reduce the cost of key management. It not only provides the multicast routing information, but also fits the robustness of the wireless networks and reduces the overhead for the security management.

Time Synchronization Protocol with Minimum Message Communication for High Latency Networks

Time synchronization is a critical component of the infrastructure of wireless sensor networks (WSN). In a high latency environment such as underwater, traditional approaches to time synchronization have limited accuracy. A new method is describe for time synchronization that takes into account clock skew, clock offset, and also propagation delay. Minimum message communication is used as a performance measure of the quality of this new time synchronization protocol.

Efficient Indoor Location Estimation using Multidimensional Indexes in Wireless Networks

Since it is hard to use GPS for tracking mobile user in indoor environments, much research has focused on techniques using existing wireless local area network infrastructure. Signal strength received at a fixed location is not constant, so fingerprinting approach which use pattern matching is popular. But this approach has to pay additional costs to determine user location. This paper proposes a new approach to find user's location efficiently using an index scheme. After analyzing characteristics of RF signals, the paper suggests the data processing method how the signal strength values for each of the access points are recorded in a radio map. To reduce computational cost during the location determination phase, multidimensional indexes for radio map with the important information which is the order of the strongest access points are used.