Showing papers in "Wireless Personal Communications in 2013"

A Survey on Near Field Communication (NFC) Technology

Abstract: Near Field Communication (NFC) as a promising short range wireless communication technology facilitates mobile phone usage of billions of people throughout the world that offers diverse services ranging from payment and loyalty applications to access keys for offices and houses. Eventually NFC technology integrates all such services into one single mobile phone. NFC technology has emerged lately, and consequently not much academic source is available yet. On the contrary, due to its promising business case options, there will be an increasing amount of work to be studied in the very close future. This paper presents the concept of NFC technology in a holistic approach with different perspectives, including communication essentials with standards, ecosystem and business issues, applications, and security issues. Open research areas and further recommended studies in terms of academic and business point of view are also explored and discussed at the end of each major subject's subsection. This comprehensive survey will be a valuable guide for researchers and academicians as well as for business world interested in NFC technology.

Multipath Routing Techniques in Wireless Sensor Networks: A Survey

Abstract: Multipath routing is an efficient technique to route data in wireless sensor networks (WSNs) because it can provide reliability, security and load balance, which are especially critical in the resource constrained system such as WSNs. In this paper we provide a survey of the state-of-the-art of proposed multipath routing protocols for WSNs, which are classified into three categories, infrastructure based, non-infrastructure based and coding based, based on the special techniques used in building multiple paths and delivering sensing data. For each category, we study the design of protocols, analyze the tradeoff of each design, and overview several representing protocols. In addition, we give a summery of design goals, challenges, and evaluation metrics for multipath routing protocols in resource constrained systems in general.

Bayesian Fusion for Indoor Positioning Using Bluetooth Fingerprints

Abstract: This paper studies the use of received signal strength indicators (RSSI) applied to fingerprinting method in a Bluetooth network for indoor positioning. A Bayesian fusion (BF) method is proposed to combine the statistical information from the RSSI measurements and the prior information from a motion model. Indoor field tests are carried out to verify the effectiveness of the method. Test results show that the proposed BF algorithm achieves a horizontal positioning accuracy of about 4.7 m on the average, which is about 6 and 7 % improvement when compared with Bayesian static estimation and a point Kalman filter method, respectively.

An Enhanced Authentication Scheme with Privacy Preservation for Roaming Service in Global Mobility Networks

Abstract: Global mobility network (GLOMONET) provides global roaming service to ensure ubiquitous connectivity for users traveling from one network to another. It is very crucial not only to authenticate roaming users, but to protect the privacy of users. However, due to the broadcast nature of wireless channel and resource limitations of terminals, providing efficient user authentication with privacy preservation is challenging. Recently, He et al. proposed a secure and lightweight user authentication scheme with anonymity for roaming service in GLOMONETs. However, in this paper, we identify that the scheme fails to achieve strong two-factor security, and suffers from domino effect, privileged insider attack and no password change option, etc. Then we propose an enhanced authentication scheme with privacy preservation based on quadratic residue assumption. Our improved scheme enhances security strength of He et al.’s protocol while inheriting its merits of low communication and computation cost. Specifically, our enhanced scheme achieves two-factor security and user untraceability.

An Advanced DV-Hop Localization Algorithm for Wireless Sensor Networks

Abstract: In emerging sensor network applications, localization in wireless sensor network is a recent area of research. Requirement of its applications and availability of resources need feasible localization algorithm with lower cost and higher accuracy. In this paper, we propose an Advanced DV-Hop localization algorithm that reduces the localization error without requiring additional hardware and computational costs. The proposed algorithm uses the hop-size of the anchor (which knows its location) node, from which unknown node measures the distance. In the third step of Advanced DV-Hop algorithm, inherent error in the estimated distance between anchor and unknown node is reduced. To improve the localization accuracy, we use weighted least square algorithm. Furthermore, location of unknown nodes is refined by using extraneous information obtained by solving the equations. By mathematical analysis, we prove that Advanced DV-Hop algorithm has lesser correction factor in the distance between anchor and the unknown node compared with DV-Hop algorithm, improved DV-Hop algorithm (Chen et al. 2008) and improved DV-Hop algorithm (Chen et al. in IEICE Trans Fundam E91-A(8), 2008), which is cause of better location accuracy. Simulation results show that the performance of our proposed algorithm is superior to DV-Hop algorithm and improved DV-Hop algorithms in all considered scenarios.

Robust Smart Card Authentication Scheme for Multi-server Architecture

Abstract: In a traditional single server smart card authentication scheme, one server is responsible for providing services to all the registered remote users. Though if a user wishes to access network services from different servers, he or she has to register with these servers separately. To handle this issue, multi-server authentication scheme has been proposed. However, almost all these schemes available in the literature are exposed to one or the other potential attack. This paper proposes robust multi-server authentication scheme using smart cards. It eliminates the use of verification table and permits the registered remote users to access multiple servers without separate registration. Moreover, users can choose and change the password securely without any assistance from the server or registration center, supports mutual authentication and session key agreement between user and the server. Furthermore, the proposed scheme withstands present potential network attacks. Besides, our scheme is validated by using BAN logic. Comparative analysis of existing schemes with our proposed scheme is also presented in terms of various security features provided and computational complexity.

A Novel Trust-Aware Geographical Routing Scheme for Wireless Sensor Networks

Abstract: Wireless sensor networks are vulnerable to a wide set of security attacks, including those targeting the routing protocol functionality. The applicability of legacy security solutions is disputable (if not infeasible), due to severe restrictions in node and network resources. Although confidentiality, integrity and authentication measures assist in preventing specific types of attacks, they come at high cost and, in most cases, cannot shield against routing attacks. To face this problem, we propose a secure routing protocol which adopts the geographical routing principle to cope with the network dimensions, and relies on a distributed trust model for the detection and avoidance of malicious neighbours. A novel function which adaptively weights location, trust and energy information drives the routing decisions, allowing for shifting emphasis from security to path optimality. The proposed trust model relies on both direct and indirect observations to derive the trustworthiness of each neighboring node, while it is capable of defending against an increased set of routing attacks including attacks targeting the indirect trust management scheme. Extensive simulation results reveal the advantages of the proposed model.

Towards Privacy Protection in Smart Grid

Abstract: The smart grid is an electronically controlled electrical grid that connects power generation, transmission, distribution, and consumers using information communication technologies. One of the key characteristics of the smart grid is its support for bi-directional information flow between the consumer of electricity and the utility provider. This two-way interaction allows electricity to be generated in real-time based on consumers' demands and power requests. As a result, consumer privacy becomes an important concern when collecting energy usage data with the deployment and adoption of smart grid technologies. To protect such sensitive information it is imperative that privacy protection mechanisms be used to protect the privacy of smart grid users. We present an analysis of recently proposed smart grid privacy solutions and identify their strengths and weaknesses in terms of their implementation complexity, efficiency, robustness, and simplicity.

Beaconing Approaches in Vehicular Ad Hoc Networks: A Survey

Abstract: A vehicular ad hoc network (VANET) is a type of wireless ad hoc network that facilitates ubiquitous connectivity between vehicles in the absence of fixed infrastructure. Beaconing approaches is an important research challenge in high mobility vehicular networks with enabling safety applications. In this article, we perform a survey and a comparative study of state-of-the-art adaptive beaconing approaches in VANET, that explores the main advantages and drawbacks behind their design. The survey part of the paper presents a review of existing adaptive beaconing approaches such as adaptive beacon transmission power, beacon rate adaptation, contention window size adjustment and Hybrid adaptation beaconing techniques. The comparative study of the paper compares the representatives of adaptive beaconing approaches in terms of their objective of study, summary of their study, the utilized simulator and the type of vehicular scenario. After implementing the representatives of beaconing approaches, we analysed the simulation results and discussed the strengths and weaknesses of these beaconing approaches with regard to their suitability to vehicular networks. Finally, we discussed the open issues and research directions related to VANET adaptive beaconing approaches.

Maximizing Lifetime of Target Coverage in Wireless Sensor Networks Using Learning Automata

Abstract: In wireless sensor networks, when each target is covered by multiple sensors, we can schedule sensor nodes to monitor deployed targets in order to improve lifetime of network. In this paper, we propose an efficient scheduling method based on learning automata, in which each node is equipped with a learning automaton, which helps the node to select its proper state (active or sleep), at any given time. To study the performance of the proposed method, computer simulations are conducted. Results of these simulations show that the proposed scheduling method can better prolong the lifetime of the network in comparison to similar existing methods.

Repackaging Attack on Android Banking Applications and Its Countermeasures

Abstract: Although anyone can easily publish Android applications (or apps) in an app marketplace according to an open policy, decompiling the apps is also easy due to the structural characteristics of the app building process, making them very vulnerable to forgery or modification attacks. In particular, users may suffer direct financial loss if this vulnerability is exploited in security-critical private and business applications, such as online banking. In this paper, some of the major Android-based smartphone banking apps in Korea being distributed on either the Android Market or the third party market were tested to verify whether a money transfer could be made to an unintended recipient. The experimental results with real Android banking apps showed that an attack of this kind is possible without having to illegally obtain any of the sender's personal information, such as the senders public key certificate, the password to their bank account, or their security card. In addition, the cause of this vulnerability is analyzed and some technical countermeasures are discussed.

A Secure and Effective Anonymous User Authentication Scheme for Roaming Service in Global Mobility Networks

Abstract: In global mobility networks, anonymous user authentication is an essential task for enabling roaming service In a recent paper, Jiang et al proposed a smart card based anonymous user authentication scheme for roaming service in global mobility networks This scheme can protect user privacy and is believed to have many abilities to resist a range of network attacks, even if the secret information stored in the smart card is compromised In this paper, we analyze the security of Jiang et al's scheme, and show that the scheme is in fact insecure against the stolen-verifier attack and replay attack Then, we also propose a new smart card based anonymous user authentication scheme for roaming service Compared with the existing schemes, our protocol uses a different user authentication mechanism, which does not require the home agent to share a static secret key with the foreign agent, and hence, it is more practical and realistic We show that our proposed scheme can provide stronger security than previous protocols

Prevention of DoS Attacks in VANET

Abstract: Privacy and Security have become an indispensable matter of attention in the Vehicular Ad-Hoc Network, which is vulnerable to many security threats these days. One of them is the Denial of Service (DoS) attacks, where a malicious node forges a large number of fake identities, i.e., Internet Protocol (IP) addresses in order to disrupt the proper functioning of fair data transfer between two fast-moving vehicles. In this paper, a distributed and robust approach is presented to defend against DoS attacks. In this proposed scheme, the fake identities of malicious vehicles are analyzed with the help of consistent existing IP address information. Beacon packets are exchanged periodically by all the vehicles to announce their presence and to become aware of the next node. Each node periodically keeps a record of its database by exchanging the information in its environment. If some nodes observe that they have similar IP addresses in the database, these similar IP addresses are identified as DoS attacks. However, it can be expected that security attacks are likely to increase in the coming future due to more and more wireless applications being developed onto the well-known exposed nature of the wireless medium. In this respect, the network availability is exposed to many types of attacks. A DoS attack on the network availability is being elaborated in this paper. A model of a product interaction for DoS prevention has been developed called "IP-CHOCK" that will lead to the prevention of DoS attacks. The proposed approach will be able to locate malicious nodes without the requirement of any secret information exchange and special hardware support. Simulation results demonstrate that the detection rate increases when optimal numbers of nodes are forged by the attackers.

A Review on Hierarchical Routing Protocols for Wireless Sensor Networks

Abstract: The routing protocol for Wireless Sensor Networks (WSNs) is defined as the manner of data dissemination from the network field (source) to the base station (destination). Based on the network topology, there are two types of routing protocols in WSNs, they are namely flat routing protocols and hierarchical routing protocols. Hierarchical routing protocols (HRPs) are more energy efficient and scalable compared to flat routing protocols. This paper discusses how topology management and network application influence the performance of cluster-based and chain-based hierarchical networks. It reviews the basic features of sensor connectivity issues such as power control in topology set-up, sleep/idle pairing and data transmission control that are used in five common HRPs, and it also examines their impact on the protocol performance. A good picture of their respective performances give an indication how network applications, i.e whether reactive or proactive, and topology management i.e. whether centralized or distributed would determine the network performance. Finally, from the ensuring discussion, it is shown that the chain-based HRPs guarantee a longer network lifetime compared to cluster-based HRPs by three to five times.

A Smart Card Based Efficient and Secured Multi-Server Authentication Scheme

Abstract: Increasing popularity of the multi-server architecture has propelled the research on the multi-server authentication schemes. Current dominating authentication schemes are smartcard based, verification table free schemes with passwords. Although these schemes have developed to be robust against most of the popular malicious attacks, they still have security weaknesses and their efficiency is generally low. In this paper, we analyze and formulate security issues in previously proposed schemes. And based on the formulation, an enhanced efficient and secure scheme is proposed. In the proposal, a novel "redundant key protection" is proposed to utilize. The proposed scheme is validated and verified by Colored Petri Nets.

Security Flaws in a Smart Card Based Authentication Scheme for Multi-server Environment

Abstract: Recently, Wang and Ma (Wireless Pers Commun, 2012. doi: 10.1007/s11277-011-0456-7 ) proposed a smart card based authentication scheme for multi-server environment. They also demonstrated that their scheme could overcome various attacks. In this paper, the security of Wang et al.'s scheme is evaluated. Our analysis shows their scheme is vulnerable to the server spoofing attack, the impersonation attack, the privileged insider attack and the off-line password guessing attack.

LISP-MN: Mobile Networking Through LISP

Abstract: The current Internet architecture was not designed to easily accommodate mobility because IP addresses are used both to identify and locate hosts. The Locator/Identifier Separation Protocol (LISP) decouples them by considering two types of addresses: EIDs that identify hosts, and RLOCs that identify network attachment points and are used as routing locators. LISP, with such separation in place, can also offer native mobility. LISP-MN is a particular case of LISP which specifies mobility. In this paper we provide a comprehensive tutorial on LISP-MN, showing its main features and how it compares to existing mobility protocols.

GRA Based Network Selection in Heterogeneous Wireless Networks

Abstract: 4G wireless networks will integrate heterogeneous technologies such as Wireless LAN and third generation (3G) cellular networks and have the capability to offer various services at any time as per user requirements, anywhere with seamless interoperability at affordable cost. One important challenge in such a heterogeneous wireless environment is to enable network selection mechanisms in order to keep the mobile users always best connected anywhere and at any time. In this paper, a multi-criteria access network selection algorithm is proposed in Worldwide Interoperability for Microwave Access---Wireless Fidelity environment, in order to facilitate the provision of high quality services and at the same time to satisfy different types of user service level agreements. Analytical hierarchy process (AHP) and grey relational analysis (GRA) methods are applying for optimal access network selection. The proposed methodology combines the AHP to decide the relative weights of criteria set according to network's performance, as well as the GRA to rank the network alternatives. The advantages of the GRA method are that the results are based on the original data, the calculations are simple and straightforward, and finally it is one of the best methods to make decision under heterogeneous wireless network environment.

Performance Evaluation of Short Range Underwater Optical Wireless Communications for Different Ocean Water Types

Abstract: This paper has presented our interesting in wireless underwater communications for different ocean water types Recent interest in ocean exploration has brought about a desire for developing wireless communication techniques in this challenging environment Due to its high attenuation in water, a radio frequency (RF) carrier is not the optimum choice Acoustic techniques have made tremendous progress in establishing wireless underwater links, but they are ultimately limited in bandwidth In traditional communication systems, constructing a link budget is often relatively straight forward In the case of underwater optical systems the variations in the optical properties of ocean water lead to interesting problems when considering the feasibility and reliability of underwater optical links The main focus of this paper is to construct an underwater link budget which includes the effects of scattering and absorption of realistic ocean water As well as we have developed the underwater optical wireless communication systems to have shorter ranges, that can provide higher bandwidth (up to several hundred Mbit/s) communications by the assistant of exciting high brightness blue LED sources, and laser diodes suggest that high speed optical links can be viable for short range application The received signal power, signal to noise ratio, bit error rate, transmitted signal bandwidth, and transmission bit rates are the major interesting parameters for different ocean water mediums as a criteria of the best signal transmission characteristics of short wireless optical communications over wide range of the affecting parameters

Home Health Gateway Based Healthcare Services Through U-Health Platform

Abstract: The Ubiquitous Health, or u-Health, service is an IT health care service using the ubiquitous computing environment. U-Health provides customized medical services. As it is a service that has developed from the current hospital visiting medical system, the u-Health service provides a patient with healthcare anywhere and anytime. In this paper, we propose a home health gateway based healthcare services through the u-Health platform. Using home health gateway, u-Health can provide health monitoring, diet, and exercise services using the healthcare decision support module in the ubiquitous environment. This approach would offer specialized services using an external content provider of DB. In addition, a doctor can provide advice to patients using the monitoring service. The proposed u-Health platform provides effective services using home health gateway in ubiquitous environments to customers, which will improve the health of chronic patients.

Multi-Objective Evolutionary Algorithm Based on Decomposition for Energy Efficient Coverage in Wireless Sensor Networks

Abstract: Wireless sensor networks (WSNs) have become a hot area of research in recent years due to the realization of their ability in myriad applications including military surveillance, facility monitoring, target detection, and health care applications. However, many WSN design problems involve tradeoffs between multiple conflicting optimization objectives such as coverage preservation and energy conservation. Many of the existing sensor network design approaches, however, generally focus on a single optimization objective. For example, while both energy conservation in a cluster-based WSNs and coverage-maintenance protocols have been extensively studied in the past, these have not been integrated in a multi-objective optimization manner. This paper employs a recently developed multi-objective optimization algorithm, the so-called multi-objective evolutionary algorithm based on decomposition (MOEA/D) to solve simultaneously the coverage preservation and energy conservation design problems in cluster-based WSNs. The performance of the proposed approach, in terms of coverage and network lifetime is compared with a state-of-the-art evolutionary approach called NSGA II. Under the same environments, simulation results on different network topologies reveal that MOEA/D provides a feasible approach for extending the network lifetime while preserving more coverage area.

IPv6 Multicast Forwarding in RPL-Based Wireless Sensor Networks

Abstract: In wireless sensor deployments, network layer multicast can be used to improve the bandwidth and energy efficiency for a variety of applications, such as service discovery or network management. However, despite efforts to adopt IPv6 in networks of constrained devices, multicast has been somewhat overlooked. The Multicast Forwarding Using Trickle (Trickle Multicast) internet draft is one of the most noteworthy efforts. The specification of the IPv6 routing protocol for low power and lossy networks (RPL) also attempts to address the area but leaves many questions unanswered. In this paper we highlight our concerns about both these approaches. Subsequently, we present our alternative mechanism, called stateless multicast RPL forwarding algorithm (SMRF), which addresses the aforementioned drawbacks. Having extended the TCP/IP engine of the Contiki embedded operating system to support both trickle multicast (TM) and SMRF, we present an in-depth comparison, backed by simulated evaluation as well as by experiments conducted on a multi-hop hardware testbed. Results demonstrate that SMRF achieves significant delay and energy efficiency improvements at the cost of a small increase in packet loss. The outcome of our hardware experiments show that simulation results were realistic. Lastly, we evaluate both algorithms in terms of code size and memory requirements, highlighting SMRF's low implementation complexity. Both implementations have been made available to the community for adoption.

Junction-Based Geographic Routing Algorithm for Vehicular Ad hoc Networks

Abstract: Vehicular Ad hoc Networks have attracted the interest of the scientific community, since many issues remain open, especially in the research area of routing techniques. In this work we propose a new position-based routing algorithm called Junction-Based Routing. The algorithm makes use of selective greedy forwarding up to the node that is located at a junction and is closer to the destination. If a local optimum is reached, a recovery strategy is applied, the key point of which is our proposed minimum angle method. We evaluate the performance of our routing protocol in real city topology. The simulated scenarios use obstacle modelling and several different Physical layer settings. Simulation results show that our proposal achieves superior performance compared to the well-known Greedy Perimeter Coordinator Routing algorithm.

A Prioritization Based Congestion Control Protocol for Healthcare Monitoring Application in Wireless Sensor Networks

Abstract: Recent developments in biosensor and wireless technology have led to a rapid progress in wearable real time health monitoring. Unlike wired networks, wireless networks are subject to more packet loss and congestion. In this paper, we propose a congestion control and service prioritization protocol for real time monitoring of patients' vital signs using wireless biomedical sensor networks. The proposed system is able to discriminate between physiological signals and assign them different priorities. Thus, it would be possible to provide a better quality of service for transmitting highly important vital signs. Congestion control is performed by considering both the congestion situation in the parent node and the priority of the child nodes in assigning network bandwidth to signals from different patients. Given the dynamic nature of patients' health conditions, the proposed system can detect an anomaly in the received vital signs from a patient and hence assign more priority to patients in need. Simulation results confirm the superior performance of the proposed protocol. To our knowledge, this is the first attempt at a special-purpose congestion control protocol specifically designed for wireless biosensor networks.

Coexistence Performance of IEEE 802.15.4 Wireless Sensor Networks Under IEEE 802.11b/g Interference

Abstract: IEEE 802.15.4 Wireless Sensor Networks (WSNs) and IEEE 802.11b/g Wireless Local Area Networks (WLANs) are often collocated, causing a coexistence issue since these networks share the same 2.4GHz Industrial, Scientific, and Medical band. In our previous work, we built a coexistence model of IEEE 802.15.4 WSNs and IEEE 802.11b/g WLANs. By identifying three distinct coexistence regions, the model explained the coexistence behavior of IEEE 802.15.4 WSNs and IEEE 802.11b/g WLANs, and the model was experimentally validated. In this paper, we improve the model by introducing two important implementation factors: the transceiver's Rx-to-Tx turnaround time and the Clear Channel Assessment partial detection effect. The enhanced model significantly improves the accuracy on explaining and predicting the coexistence performance of IEEE 802.15.4 WSNs in the real-life environment. Furthermore, under the guidance of the model, the coexistence performance of IEEE 802.15.4 WSNs is extensively investigated in various coexistence scenarios by analysis, simulation and experiments, respectively. The simulation and experimental results agree with our analysis. The coexistence model is believed to be helpful in resolving the coexistence issue.

An Energy-Efficient Threshold-Based Clustering Protocol for Wireless Sensor Networks

Abstract: Energy-constrained wireless sensor networks (WSNs) have been deployed widely for monitoring and surveillance purposes. Since sensor nodes (SNs) have significant power constraints (battery life), energy-efficient protocols must be employed to prolong the network lifetime. In this paper, we propose an energy-efficient protocol which provides a new way of creating distributed clusters. This protocol is a modified version of Low Energy Adaptive Clustering Hierarchy (LEACH) protocol. The experimental results show that our protocol that takes into account both the residual energy at each SN and the distance between the SNs outperforms LEACH protocol in terms of first node death time and average residual energy.

Computer Simulations of VANETs Using Realistic City Topologies

Abstract: Researchers in vehicular ad hoc networks (VANETs) commonly use simulation to test new algorithms and techniques. This is the case because of the high cost and labor involved in deploying and testing vehicles in real outdoor scenarios. However, when determining the factors that should be taken into account in these simulations, some factors such as realistic road topologies and presence of obstacles are rarely addressed. In this paper, we first evaluate the packet error rate (PER) through actual measurements in an outdoor road scenario, and deduce a close model of the PER for VANETs. Secondly, we introduce a topology-based visibility scheme such that road dimension and geometry can be accounted for, in addition to line-of-sight. We then combine these factors to determine when warning messages (i.e., messages that warn drivers of danger and hazards) are successfully received in a VANET. Through extensive simulations using different road topologies, city maps, and visibility schemes, we show these factors can impact warning message dissemination time and packet delivery rate.

Joint Beamforming and Power Allocation for Cognitive MIMO Systems Under Imperfect CSI Based on Game Theory

Abstract: The problem of joint beamforming and power allocation for cognitive multi-input multi-output systems is studied via game theory. The objective is to maximize the sum utility of secondary users (SUs) subject to the primary user (PU) interference constraint, the transmission power constraint of SUs, and the signal-to-interference-plus-noise ratio (SINR) constraint of each SU. In our earlier work, the problem was formulated as a non-cooperative game under the assumption of perfect channel state information (CSI). Nash equilibrium (NE) is considered as the solution of this game. A distributed algorithm is proposed which can converge to the NE. Due to the limited cooperation between the secondary base station (SBS) and the PU, imperfect CSI between the SBS and the PU is further considered in this work. The problem is formulated as a robust game. As it is difficult to solve the optimization problem in this case, existence of the NE cannot be analyzed. Therefore, convergence property of the sum utility of SUs will be illustrated numerically. Simulation results show that under perfect CSI the proposed algorithm can converge to a locally optimal pair of transmission power vector and beamforming vector, while under imperfect CSI the sum utility of SUs converges with the increase of the transmission power constraint of SUs.

Technology Acceptance Model for the Use of Tablet PCs

Abstract: Tablet personal computers (tablet PCs) are popular electronic devices worldwide. They influence many aspects of our social lives. Compared with laptop computers, tablet PCs feature characteristics including enhanced portability and display quality. The purposes of this study were to examine users' attitudes toward tablet personal computers and identify the effects of external factors. This study extended the technology acceptance model and used perceived mobility and viewing experience as the external variables in the proposed model. This study used a web-based survey of 511 participants and found that perceived usefulness and perceived ease of use were key determinants of attitude toward tablet personal computers. Also, the perceived ease of use and usefulness of tablet PCs were significantly enhanced by perceived mobility and viewing experience. In addition, all traditional relationships from the origin technology acceptance model were supported. Lastly, both implications of the study and areas of future research are discussed.

Artificial Neural Network Based Vertical Handoff Algorithm for Reducing Handoff Latency

Abstract: One of the most challenging topics for next generation wireless networks is vertical handoff concept since several wireless technologies are assumed to cooperate. Plenty of parameters related to user preferences, application requirements, and network conditions, such as; data rate, service cost, network latency, speed of mobile, battery level, interference ratio and etc. must be considered in vertical handoff process along with traditional RSSI information. In this study, a new artificial neural network based handoff decision algorithm is proposed in order to reduce the handoff latency of smart terminal deployed in aforementioned wireless heterogeneous infrastructures. The prominent parameters data rate, monetary cost and RSSI information are taken as inputs of the developed vertical handoff decision system. Performance results of the proposed system are also compared with those of classical Multiple Attribute Decision Making method Simple Additive Weighting, and of some other artificial intelligence based algorithms. According to the results obtained, the proposed neural network based vertical handoff decision algorithm is able to determine whether a handoff is necessary or not properly, and selects the best candidate access network considering the abovementioned parameters. The results also show that, the neural network based algorithm developed significantly reduces the handoff latency while the number of handoffs, which is another vital performance metric, is still reasonable.