Mobile Users Access Research Articles

The diffusion of mobile social networking: Exploring adoption externalities in four G7 countries

The diffusion of Mobile Social Networking (MSN) is driven by the development of new devices and improved mobile broadband. The instantaneous nature of MSN exchanges enhances the value of data access for mobile users, which generates network externalities. We explore the presence of these externalities in the diffusion of MSN in France, the UK, the US and Germany. For these countries, we compare estimates of two diffusion models: the Bass model and the Bemmaor model. We find evidence of network externalities in MSN adoption for all of these countries, captured by the left skew of the cumulative adoption curves. This evidence is confirmed even after taking into account the contrasting effect of heterogeneity in the propensity to adopt. Our results provide content providers, operators and regulators with insights about marketing strategies, helping with policy formulation under the combined presence of network externalities and heterogeneity.

Video delivery in heterogenous crans: architectures and strategies

Video traffic has become a major part of mobile data traffic, and will keep growing in the coming years. The performance of video delivery is fundamentally constrained by the structure of the underlying wireless networks. The recently proposed heterogeneous cloud access networks have been widely recognized as an inevitable evolution trend of the current cellular system toward the future 5G system, where multiple hybrid radio access technologies coexist to provide flexible access for mobile users. As a key enabling functional block for high-performance video delivery, a powerful centralized baseband processing unit pool is adopted to control all the radio access technologies, and possibly facilitate the video encoding and transmission, which opens up the potential to achieve higher throughput, lower traffic delay, and greater robustness compared to its basic baseband processing unit counterpart without central control functions. However, such a centralized control framework also raises many new research challenges to be addressed. In this article, we provide an overview of the state-of-the-art video delivery architectures and video packet transmission strategies in heterogeneous cloud radio access networks, with highlights on the networking architectures, transmission strategies, performance analysis, and design challenges. This article also sheds some light on the design principles for future big-dataoriented wireless networks.

The Mobile Web: Amplifying, but Not Creating, Changemakers

the technology that will transform the lives of the world’s poor. Describing Internet connectivity as “the foundation of the knowledge economy” and a human right, Mark Zuckerberg, founder of Facebook, launched a philanthropic initiative, Internet.org, to provide free access to Facebook and other select Internet sites. Google is experimenting similarly with balloons and broadcast frequencies—such as “white space” from the unused television spectrum—to drive access, and it also has launched Google Zero in partnership with mobile network operators to provide free access to select Google services. The Wikipedia Foundation also has joined the movement, partnering with 29 operators in 34 countries to provide mobile users access to Wikipedia Zero, with the goal of building “a world in which every single human on the planet has equal access to the sum of all knowledge.” Development organizations also have embraced technology’s potential to reduce poverty; the World Bank argues that smartphones with data connectivity “not only empower individuals but have important cascade effects stimulating growth, entrepreneurship, and productivity throughout the economy as a whole.” Both private-sector and development organizations thus share a common belief that access is the key to unlocking technology’s full potential to contribute to economic growth. However, because technology tends to amplify existing patterns and intent, focusing solely on access is likely to entrench existing inequalities further. To counter any amplification of the culture of poverty and oppression, people in the developing world will need to have the capacity to produce digital content that can enhance local knowledge and strengthen champions of change. This essay first outlines the economic argument that dominates the case for using the mobile phone in development, and then shows that technological con-

Selecting proper wireless network interfaces for user experience enhancement with guaranteed probability

With the increasing capabilities of mobile phones, mobile users access data via wireless interfaces pervasively. Although WiFi has limited coverage and resulted in a bigger delay of data access, it is not uncommon that mobile users are willing to use WiFi to transmit data to decrease communication costs instead of 3G. Hence it is reasonable to use delay tolerance strategies to balance execution time, energy consumption, and communication cost. In this paper, we model mobile user experience as a combination of three random variables (energy consumption, execution time and communication cost). We present a wireless interface scheduling algorithm to select proper wireless interfaces for a set of data-dependent sporadic tasks to enhance user experience under the constraints of execution time, energy consumption, and communication cost with a guaranteed confidence probability in a delay-tolerant environment. The experimental results show that our approach can effectively enhance the user experience.

Urban 802.11 Community Networks for Mobile Users: Current Deployments and Prospectives

Few years ago some network operators launched a new service called Community Networks, where each subscriber shares its residential Internet connection with other subscribers of the same operator via his 802.11 access point. Due to the high access point density in urban areas, community networks have the potential to offer high data rate wireless Internet access for mobile users, going beyond the currently available hot-spots, which are typically deployed in a limited number of isolated locations (e.g., airports, cafes). Unlike cellular networks, the locations of community network access points is not centrally planned. We evaluate existing community networks using a participatory sensing application called Wi2Me. First, we analyze different metrics in order to characterize community networks. Second, we take advantage of this unique 802.11 network (in terms of density and coverage) to study how mobility can be supported by identifying drawbacks and proposing some possible solutions.

IPv6 based relay gateway protocol in hybrid networks

During the past few years, WMAN (Wireless Metropolitan Area Network) and WLAN (Wireless Local Area Network) provided fast, convenient and reliable solution for all kinds of users. With the development of the communication technology, the future wireless networks will allow mobile users access Internet anywhere, anytime. Therefore, it is a natural trend to combine different wireless networks to provide a seamless roaming for users. It is feasible for mobile terminal which have multiple modes to handoff between different networks. A relay gateway protocol for the WLAN-mode nodes (mono-mode WLAN nodes and dual-mode nodes) in the hybrid network of IEEE 802.16 WMANs and IEEE 802.11 WLANs is proposed to provide wider mobility. Dual-mode mobile nodes with good service can provide WLAN links to nearby WLAN-mode nodes with bad service or out of the WLAN coverage. Simulation results show that the relay gateway scheme can improve network performance of the hybrid networks. Moreover, the relay gateway method can bring additional service coverage and increase the capacity of WMANs and WLANs.

Nodes organization for channel assignment with topology preservation in multi-radio wireless mesh networks

The wireless mesh network is a new emerging broadband technology providing the last-mile Internet access for mobile users by exploiting the advantage of multiple radios and multiple channels. The throughput improvement of the network relies heavily on the utilizing the orthogonal channels. However, an improper channel assignment scheme may lead to network partition or links failure. In this paper we consider the assignment strategy with topology preservation by organizing the mesh nodes with available channels, and aim at minimizing the co-channel interference in the network. The channel assignment with the topology preservation is proved to be NP-hard and to find the optimized solution in polynomial time is impossible. We have formulated a channel assignment algorithm named as DPSO-CA which is based on the discrete particle swarm optimization and can be used to find the approximate optimized solution. We have shown that our algorithm can be easily extended to the case with uneven traffic load in the network. The impact of radio utilization during the channel assignment process is discussed too. Extensive simulation results have demonstrated that our algorithm has good performance in both dense and sparse networks compared with related works.

Open Wireless Networks on University Campuses

Open wireless networks raise privacy issues and entail increased risk of malicious attacks and illegal downloading activities. Such networks are nonetheless attractive-particularly to universities-because they enhance usability and thus expand access to nonsensitive system resources. At universities, such access brings numerous benefits to students, faculty, and the surrounding community alike. Here, the authors describe the challenges of removing individual user authentication requirements at the perimeter of a university network in which mobile device users access system resources over wireless links to the wired infrastructure. The authors discuss how to mitigate the security and privacy risks entailed in an open network of this sort, and also describe how IT departments can vary the network's degree of openness.

Dual-threshold admission control for non-real-time traffic in wireless data networks

Non-real-time services are an important category of network services in future wireless networks. When mobile users access non-real-time services, mobile users are usually concerned with the total time to complete their data transfer. In addition, system providers expect that channel utilization should be as high as possible because radio channels are limited. Therefore, it is crucial to design a system that satisfies the total completion time requirement of mobile users while maximizes channel utilization. In this paper, we design an optimal call admission control scheme that uses two thresholds; one threshold is used to determine whether or not to accept a new call arrival into a cell, and the other threshold is used to limit the total number of calls in a cell. An analysis is developed to evaluate the performance of the proposed call admission control scheme. Numerical results show that the proposed scheme not only satisfies mobile users’ quality-of-service requirements (in terms of the total completion time and hand-off dropping probability) but also maximizes channel utilization.

End-to-End Security Across Wired-Wireless Networks for Mobile Users

ABSTRACT Recent advances in mobile computing and wireless communication technologies are enabling high mobility and flexibility of anytime, anywhere service access for mobile users. As a result, network connections of such users often span over heterogeneous networking environments consisting of wired and wireless networking technologies. Both network heterogeneity and user mobility make the securing of data transmission over heterogeneous networks challenging and complex. In this paper, we focus on the challenge of providing secure end-to-end network transmissions to wireless mobile users. To minimize service interruption during ongoing secure sessions of mobile users, we present the design and implementation of an approach based on the well-known Internet Protocol Security (IPSec) standard. We conducted a performance evaluation of our implementation using a Voice over IP (VoIP) application over an actual network testbed. Our empirical performance results demonstrate a packet loss improvement of 17% to 34% (for various VoIP packet sizes) and a handoff delay improvement of almost 24% validating the high efficiency of our proposed approach.

Adapting Web Content to Mobile User Agents

In this article, we describe an adaptation proxy we developed as a part of a Kontti research project at VTT Information Technology that lets mobile users access Web content that's not directly targeted to mobile user agents. More and more content is now available on the Internet, and there's a growing need for mobile users to be able to access it. Thus the authors describe the adaptation proxy, which lets mobile users access Web content that's not directly targeted to user agents of mobile devices. The adaptation proxy can adapt Extensible Hypertext Markup Language (XHTML) documents into XHTML mobile profile (XHTML MP) and Wireless Markup Language (WML), and can perform media adaptation. At the system's core is an adaptation framework to which new source and target XML languages can be introduced with relatively little effort.

Performance of CDMA/PRMA as an Access Technique for Integrated Services in a UMTS High Altitude Platform System

High Altitude Platforms (HAPs) have gained a great interest in recent years. HAP systems will be global in nature but national in service provision. They will deliver IMT-2000 mobile and fixed wireless access using the proposed IMT-2000 terrestrial component radio transmission technologies and protocols. Under the above consideration, in this paper the performance of a MAC protocol based on the combination of the well-known Packet Reservation Multiple Access (PRMA) scheme with Code Division Multiple Access (CDMA) technologies in a Frequency Division Duplex (FDD) mode is studied, for a HAP operating at the 2 GHz frequency band at an altitude of 22 km. The impact of acknowledgement delay has been examined through computer simulations, along with the selection of suitable channel access functions (CAFs) to control the access of mobile users. Moreover the protocol performance is investigated in a cellular HAP environment and compared to that of a ground-based system. Finally, different traffic scenarios have been considered in order to investigate the access delay for non-real time traffic and the packet dropping performance for real time traffic.

Personal service areas for mobile Web applications

Location-based mobile services let wireless mobile users access Web-based information about resources in their immediate vicinities. The authors describe an algorithm that draws on context mobility elements, such as the user's travel direction and speed, to form personal service areas. Their experimental context-aware tourist information system (CATIS) leverages XML technologies and Web services to provide tourist information to mobile users based on these personal service areas and the users' preferences. Because Web service performance depends on the underlying databases, the authors also developed a layered caching scheme for storing environmental data to improve response time.

Packet Multiple Access for Channel With Binary Feedback, Capture, and Multiple Reception

This paper considers the multiple access of mobile users to a common wireless channel. The channel is slotted and the binary feedback (empty slot/nonempty slot) is sent to all accessing users. If a slot was not empty and only one user transmitted in it, the transmission is considered successful. Only the user, which had the successful transmission, receives information about its success. In the Introduction, the paper gives a review of known multiple-access algorithms for such a channel. Then our algorithm is constructed that has none of the weaknesses of the algorithms discussed in the Introduction. The algorithm is stable, in contrast to the ALOHA algorithm. It can work in a channel with capture and multiple reception. Without them, the algorithm has a throughput of 0.2891. It is shown how capture and multiple reception can increase the algorithm throughput to 0.6548 and decrease the packet delay for some fading models. The average packet delay and variance are found for two fading models. The models are Rayleigh fading with incoherent and coherent combining of joint interference power. The accessing traffic is Poisson.

An Internet vision: the invisible global infrastructure

This paper takes us on a short journey from traditional desktop computing to the three emerging dimensions of: Nomadicity (the system support needed to provide a rich set of computing and communication capabilities and services to nomads as they move from place to place in a way that is transparent, integrated, convenient and adaptive); embeddedness (small intelligent devices embedded in the physical world and connected to the Internet); and ubiquity (Internet service availability wherever the nomad travels on a global basis). These three dimensions give us a powerful system that supports global access for mobile users interacting with smart spaces. When we add intelligence distributed across this global infrastructure, we form a new “space”, which is the basis of a vision I articulated for the Internet in 1969 and which has yet to be achieved. In that vision, I foresee that the Internet will essentially be an invisible global infrastructure serving as a global nervous system for the peoples and processes of this planet.

Scalable, error-resilient, and high-performance video communications in mobile wireless environments

A novel mobile communications system is proposed, which provides not only effective but also efficient video access for mobile users when communicating over low-bandwidth error-prone wireless links. The middleware implemented by a mobile proxy server at the mobile support station is designed for the seamless integration of mobile users with video servers, so the specific details of the underlying protocols and source/channel coding techniques are hidden to both the video server and mobile client. Based on the concept of application-level framing, the application (video codec in our case) plays a significant role in network communications that most of functionalities of the system are implemented as part of the application. As such, at the application layer, adaptive source- and channel-coding techniques are developed to jointly provide the user with the highest possible video quality. For efficient source coding, our high-performance low-complexity video-coding algorithm called a 3-D significance-linked connected component analysis (3D-SLCCA) is chosen. Due to its high robustness against channel-error propagation, 3D-SLCCA is well suited for wireless environments. For error-resilient channel coding, a multilayer transmission error-control mechanism is developed. Since there is no additional requirement imposed on either the mobile client or the video server, mobile users interact with the server in exactly the same way as stationary users. Extensive computer experiments demonstrate the effectiveness of the proposed system.

Performance of CDPD with timed hop and forced hop

Cellular Digital Packet Data (CDPD) offers mobile users access to a low-cost, ubiquitous, wireless data network. CDPD can be overlaid on existing AMPS analog cellular systems and share their infrastructure equipment on a non-interfering basis. To prevent interference with the voice activities, CDPD performs forced hop to a channel stream when a voice request is about to use the RF channel occupied by that channel stream. In addition, several timers and system parameters are defined in CDPD to ensure that the normal AMPS activities are not affected by CDPD. This article investigates how the channel selection algorithms, the timers and other parameters affect the performance of AMPS/CDPD systems. Specifically, we study the trade-off between mean CDPD channel holding time and voice incompletion probability. Our study indicates that if AMPS exercises the most-idle channel selection algorithm and CDPD exercises the least-idle channel selection algorithm, then the largest mean CDPD channel holding time is expected. On the other hand, if AMPS exercises the least-idle channel selection algorithm, then the smallest voice incompletion probability is expected.

Universal broadband mobility target for post-TINA infrastructure: toward the fourth generation

Future universal broadband mobile services present a challenge for telecommunications architectures, control, and management. The focus of the future mobile (fourth) generation vision is turned from capacity to services, from radio to network-wide issues. New types of applications will evolve that should be supported by an adequate programmable intelligent telecommunications infrastructure. A convergence between telecom and datacom networks will happen based on the communications middleware concept, which will provide universal secure connectivity between mobile users and their applications. Actual specifications of TINA-C do not address all such necessary issues. There is a need for technology evolution, enhancement, and integration to meet these new requirements at different levels. The author the concept of the universal broadband mobile telecommunications systems (UBMTS, or simply UBM) described as fourth-generation mobile systems. The UBMTS objective is both to extend mobile user access to the range of broadband services that will exist for broadband integrated services digital network (B-ISDN) users, and to extend the customization of new services related to personal communications systems (PCS) users.

Trading CDPD availability and voice blocking probability in cellular networks

Cellular digital packet data (CDPD) offers mobile users access to a low-cost, ubiquitous, wireless data network. CDPD can be overlaid on existing AMPS analog cellular systems and share their infrastructure equipment on a noninterfering basis. Since CDPD utilizes the idle radio resources of AMPS, it is important to ensure that the normal AMPS activities are not affected by CDPD. Several timers and system parameters are defined in CDPD for this purpose. This article investigates how these timers and parameters affect the performance of AMPS/CDPD systems. Our study provides guidelines for the selection of input parameters to aid CDPD network planning. Specifically, we study the trade-off between CDPD availability and voice blocking probability. CDPD availability is defined as the proportion of time that the RF channels can be used to transmit CDPD data. We observe that selecting too large values for CDPD dwell time and the maximum number of CDPD channel streams will degrade the voice blocking probability without improving CDPD availability. On the other hand, selecting a too large value for the CDPD layoff time will degrade CDPD availability without improving voice blocking probability.