Understanding emotions experienced when using a mobile phone in public: The social usability of mobile (cellular) telephones

The widespread and continued growth of mobile telephony within society means that protocols regarding acceptable public use are being continually redefined. In order to understand the different needs and motivations of mobile phone users and to assist with the development of effective policy, it is important first to consider the phone-related behaviours with which people are comfortable and those with which they become annoyed. A survey of 184 young adults was undertaken to explore the relationships between their comfort making and receiving mobile phone calls in different social contexts, their affective responses to public mobile phone use by others, and how such factors relate to key personal attributes and specific beliefs regarding calling behaviour. Mobile phone users differed in the extent to which they felt comfortable making and receiving calls in different social contexts and were less annoyed by others using mobile phones in locations where they themselves felt most comfortable making calls. Three important influences which predicted behavioural measures of phone use were found to be views regarding the application of public restrictions, desire to remain personally contactable and ‘social usability’ or anxiety regarding phone use in the presence of others. User personality and individual attributes such as age and gender were also found to be differentially associated with some aspects of phone-related behaviours.     

Real-time traffic support in heterogeneous mobile networks

Multi-hop mobile wireless networks have been proposed for a variety of applications where support for real-time multimedia services will be necessary. Support for these applications requires that the network is able to offer quality of service (QoS) appropriate for the latency and jitter bounds of the real-time application constraints. In this paper, we analyze the primary challenges of realizing QoS in mobile wireless networks with heterogeneous devices and propose a QoS framework for real-time traffic support. We address the problem in three ways: estimate the path quality for real-time flows, mitigate the impact of node heterogeneity on service performance, and reduce the impact of interfering non-real-time traffic. Specifically, our proposed QoS framework first utilizes a call setup protocol at the IP layer to discover paths for real-time flows, as well as to perform admission control by accurate service quality prediction. The underlying routing protocol also enables transparent path selection among heterogeneous nodes to provide stable paths for real-time traffic delivery. We then use a prioritized MAC protocol to provide priority access for flows with real-time constraints to reduce interference from unregulated non-real-time traffic. We foresee the utility of our proposed solution in heterogeneous mobile networks, such as campus or community-wide wireless networks. In these environments, resource-rich or fixed wireless routers may be leveraged to achieve better service quality when heterogeneity of node capability and movement is significant. Through experimental results, we demonstrate the utility and efficiency of our approach. Yuan Sun received her Ph.D. from the Department of Computer Science at the University of California, Santa Barbara in 2005. She worked with Prof. Elizabeth Belding-Royer in the MOMENT Lab. Her thesis work focused on providing QoS for mobile networks. Dr. Sun is currently employed at Google. Elizabeth M. Belding-Royer is an Associate Professor in the Department of Computer Science at the University of California, Santa Barbara. Elizabeth’s research focuses on mobile networking, specifically ad hoc and mesh networks, multimedia, monitoring, and advanced service support. She is the founder of the Mobility Management and Networking (MOMENT) Laboratory (moment.cs.ucsb.edu) at UCSB. Elizabeth is the author of over 50 papers related to mobile networking and has served on over 40 program committees for networking conferences. Elizabeth served as the TPC Co-Chair of ACM MobiCom 2005 and IEEE SECON 2005, and is currently on the editorial board for the IEEE Transactions on Mobile Computing. Elizabeth is the recipient of an NSF CAREER award, and a 2002 Technology Review 100 award, awarded to the world’s top young investigators. See ebelding for further details. Xia Gao is currently a Staff Engineer at Ubicom. He received his Ph.D of ECE from the University of Illinois at Urbana-Champaign in 2001. Before joining Ubicom, he had worked in DoCoMo Communications Laboratory for 4 years where he conducted research on 3G-4G wireless communication system and handset technologies and WiFi systems. He has published more than 30 conference and journal papers. He has chaired several International conferences and served as TPC members for many others. He is a member of IEEE and a honored member of Sigma Xi. James Kempf is a Research Fellow at DoCoMo USA Laboratories. He holds a Ph.D. from the University of Arizona, Tucson, AZ. Previously, James worked at Sun Microsystems for 13 years, and contributed to numerous research projects involving wireless networking, mobile computing, and service discovery. James is a former member of the Internet Architecture Board, and co-chaired the SEND and Seamoby IETF Working Groups. James continues to be an active contributor to Internet standards in the areas of security and mobility for next generation, Internet protocol-based mobile systems.     

An analytical study of the communication cost of data-centric storage in mobile ad hoc networks

Data-centric storage is a fundamental data management paradigm in wireless multihop networks. Originally introduced for wireless sensor networks, existing approaches are in principle also applicable in mobile ad hoc networks. However, the mobility of such networks strongly impacts storage performance in general and communication cost in particular. While this is recognized in the research community, a detailed account of the performance in terms of communication cost is lacking.In this article, we provide a detailed study of the communication cost of previously proposed data-centric storage mechanisms that are viable in mobile ad hoc networks. We first introduce a comprehensive analytical model that suitably characterizes the communication cost of data-centric storage mechanisms from the literature. We then use our model to evaluate the considered mechanisms in comparative terms as a function of relevant system parameters, including the amount of considered data, the frequency of data updates and queries, and node speed. Our results give a detailed account of data-centric storage performance and are able to identify the most suitable ranges of operation for each of the considered mechanisms.     

Service discovery in mobile ad hoc networks: an overall perspective on architectural choices and network layer support issues

Service discovery is indispensable to ad hoc networking where establishing a stand-alone and self-configurable communication environment is the main objective. In this paper, we first discuss possible service discovery architectures along with the required network support for their implementation in mobile ad hoc networks. We then propose a distributed service discovery architecture that relies on a virtual backbone for locating and registering available services within a dynamic network topology. Our proposal consists of two independent components: (i) formation of a virtual backbone and (ii) distribution of service registrations, requests, and replies. The first component creates a mesh structure from a subset of a given network graph that includes the nodes acting as service brokers and also a subset of paths (which we refer to as virtual links) connecting them. Service broker nodes (SBNs) constitute a dominating set, i.e. all the nodes in the network are either in this set or only one-hop away from at least one member of the set. The second component establishes sub-trees rooted at service requesting nodes and registering servers for efficient dissemination of the service discovery control messages. Extensive simulation results are provided for comparison of performance measures, i.e. latency, success rate, and control message overhead, when different architectures and network support mechanisms are utilized in service discovery.     

Impact of node distance on selfish replica allocation in a mobile ad-hoc network

Many data replication techniques have been proposed to minimize performance degradation caused by network partitioning in a mobile ad-hoc network. Most of them assume that all mobile nodes collaborate fully in terms of sharing their memory space. However, in reality, some nodes may selfishly decide to only cooperate partially, or not at all, with other nodes. Recently, a new approach to selfish replica allocation has been proposed to handle node selfishness. However, there is still much room for improvement. We empirically observe that the previous selfish replica allocation strategy suffers from long query delay and poor data accessibility, because it utilizes only non-selfish nodes that may be faraway nodes. In this paper, we propose a novel replica allocation strategy in the presence of selfish nodes, that takes into account both selfish behavior and node distance. Moreover, through a novel node leveling technique, we utilize the memory space of all connected nodes, including selfish nodes. The conducted simulations demonstrate that the proposed strategy outperforms existing replica allocation techniques in terms of data accessibility, query delay, and communication cost.     

OLSR performance measurement in a military mobile ad hoc network

Wireless ad hoc networks are autonomous, self-configurating and adaptive. Thus, such networks are excellent candidates for military tactical networks, where their ability to be operational rapidly and without any centralized entity is essential. As radio coverage is usually limited, multihop routing is often needed; this is achieved by an ad hoc routing protocol supporting nodes mobility. In this paper, we present performance measurements of the Optimized Link State Routing (OLSR) routing protocol, having the status of IETF RFC. The measurements are performed at CELAR site on a platform representative of military scenarios in urban areas. This platform consists of ten routers, eight PDAs and laptops using a IEEE 802.11b radio interface and implementing OLSR v7. Some nodes are mobile within vehicles. The emphasis of the measurements is on the performance of the network (route repair, network convergence speed, user traffic performance) in presence of this mobility.     

Secure sensors data acquisition and communication protection in eHealthcare: Review on the state of the art

Recent advances in hardware technology have led to the development of low cost, power efficient and more feature rich devices that are amongst the most critical parts of communication networks. These devices or sensors can now sense data with more accuracy, process it by themselves and send it to the neighboring node or the sink node. However, robust and reliable security mechanisms are not yet properly implemented on these sensors due to their limited energy and computation power. Sensors also play a very important role in eHealthcare systems where ubiquitous patient monitoring is performed. As data is generated from the sensor nodes, reliable, secure and attack-resistant data acquisition and transmission is important for an efficient eHealthcare systems. This survey focuses on security issues of sensors data acquisition and transmission protocols, describing their main security features and comparing them in the context of a secure eHealthcare system. A taxonomy of open issues and future challenges is also discussed with respect to specific security metrics described in the paper.     

Towards connecting people,locations and real-world events in a cellular network

The success of personal mobile communication technologies has led an emerging expansion of the telecommunication infrastructure but also to an explosion to mobile broadband data traffic as more and more people completely rely on their mobile devices, either for work or entertainment. The continuously interaction of their mobile devices with the mobile network infrastructure creates digital traces that can be easily logged by the network operators. These digital traces can be further used, apart from billing and resource management, for large-scale population monitoring using mobile traffic analysis. They could be integrated into intelligent systems that could help at detecting exceptional events such as riots, protests or even at disaster preventions with minimal costs and improve people safety and security, or even save lives. In this paper we study the use of fully anonymized and highly aggregate cellular network data, like Call Detail Records (CDRs) to analyze the telecommunication traffic and connect people, locations and events. The results show that by analyzing the CDR data exceptional spatio-temporal patterns of mobile data can be correlated to real-world events. For example, high user network activity was mapped to religious festivals, such as Ramadan, Le Grand Magal de Touba and the Tivaouane Maouloud festival. During the Ramadan period it was noticed that the communication pattern doubled during the night with a slow start during the morning and along the day. Furthermore, a peak increase in the number of voice calls and voice calls duration in the area of Kafoutine was mapped to the Casamance Conflict in the area which resulted in four deaths. Thus, these observations could be further used to develop an intelligent system that detects exceptional events in real-time from CDRs data monitoring. Such system could be used in intelligent transportation management, urban planning, emergency situations, network resource allocation and performance optimization, etc.     

Using a new protocol to enhance path reliability and realize load balancing in mobile ad hoc networks

In this paper we introduce a novel end-to-end approach for achieving the dual goal of enhanced reliability under path failures, and multi-path load balancing in mobile ad hoc networks (MANETs). These goals are achieved by fully exploiting the presence of multiple paths in mobile ad hoc networks in order to jointly attack the problems of frequent route failures and load balancing. More specifically, we built a disjoint-path identification mechanism for maintaining multiple routes between two endpoints on top of the Stream Control Transmission Protocol (SCTP), and the Dynamic Source Routing (DSR) protocol. A number of additional modifications are incorporated to the SCTP protocol in order to allow its smooth operation. The proposed approach differs from previously related work since it consists of an entirely end-to-end scheme built on top of a transport layer protocol. We provide both analytical and simulation results that prove the efficiency of our approach over a wide range of mobility scenarios.     

Choosing a wrong mobile communication price plan: An empirical analysis of predictors of the degree of tariff misfit among flat rate subscribers in Germany

Worldwide, more and more users of mobile communication services (MCS) are in tariffs which decouple the level of customer usage of one or several MCS (voice calls, Internet access, SMS) from the fixed monthly charge of mobile network operators (MNOs). However, consumers may inappropriately subscribe to such a flat rate because other usage-dependent price schemes are available which more closely match with their MCS use patterns. Surprisingly, little research has examined how the degree of consumer tariff misfit is correlated with socio-demographic, contract-, MCS-usage- and device-related subscriber characteristics. The present paper analyzes such associations. We develop two volume-based measures of the degree of tariff misfit in a sample of 1,274 subscribers of an MNO in Germany who had switched into a “grand flat rate” which includes unlimited national call minutes, mobile Internet traffic as well as national SMS. We find that the degree of tariff misfit is significantly higher among subscribers who are older, live in West Germany, have a longer MNO tenure, have larger monthly usage volume variations of voice calls, mobile Internet and SMS and are equipped with a device which is not an Apple iPhone. Implications of the results are discussed for MNO practitioners and for future scholarly work.