By Topic

Mobile Computing, IEEE Transactions on

Issue 5 • Date May 2014

Filter Results

Displaying Results 1 - 16 of 16
  • A Study on False Channel Condition Reporting Attacks in Wireless Networks

    Publication Year: 2014 , Page(s): 935 - 947
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1992 KB) |  | HTML iconHTML  

    Wireless networking protocols are increasingly being designed to exploit a user's measured channel condition; we call such protocols channel-aware. Each user reports the measured channel condition to a manager of wireless resources and a channel-aware protocol uses these reports to determine how resources are allocated to users. In a channel-aware protocol, each user's reported channel condition affects the performance of every other user. The deployment of channel-aware protocols increases the risks posed by false channel-condition feedback. In this paper, we study what happens in the presence of an attacker that falsely reports its channel condition. We perform case studies on channel-aware network protocols to understand how an attack can use false feedback and how much the attack can affect network performance. The results of the case studies show that we need a secure channel condition estimation algorithm to fundamentally defend against the channel-condition misreporting attack. We design such an algorithm and evaluate our algorithm through analysis and simulation. Our evaluation quantifies the effect of our algorithm on system performance as well as the security and the performance of our algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A System for Automatic Notification and Severity Estimation of Automotive Accidents

    Publication Year: 2014 , Page(s): 948 - 963
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2565 KB) |  | HTML iconHTML  

    New communication technologies integrated into modern vehicles offer an opportunity for better assistance to people injured in traffic accidents. Recent studies show how communication capabilities should be supported by artificial intelligence systems capable of automating many of the decisions to be taken by emergency services, thereby adapting the rescue resources to the severity of the accident and reducing assistance time. To improve the overall rescue process, a fast and accurate estimation of the severity of the accident represent a key point to help emergency services better estimate the required resources. This paper proposes a novel intelligent system which is able to automatically detect road accidents, notify them through vehicular networks, and estimate their severity based on the concept of data mining and knowledge inference. Our system considers the most relevant variables that can characterize the severity of the accidents (variables such as the vehicle speed, the type of vehicles involved, the impact speed, and the status of the airbag). Results show that a complete Knowledge Discovery in Databases (KDD) process, with an adequate selection of relevant features, allows generating estimation models that can predict the severity of new accidents. We develop a prototype of our system based on off-the-shelf devices and validate it at the Applus+ IDIADA Automotive Research Corporation facilities, showing that our system can notably reduce the time needed to alert and deploy emergency services after an accident takes place. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive Scheduling in MIMO-Based Heterogeneous Ad Hoc Networks

    Publication Year: 2014 , Page(s): 964 - 978
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1103 KB) |  | HTML iconHTML  

    The demands for data rate and transmission reliability constantly increase with the explosive use of wireless devices and the advancement of mobile computing techniques. Multiple-input and multiple-output (MIMO) technique is considered as one of the most promising wireless technologies that can significantly improve transmission capacity and reliability. Many emerging mobile wireless applications require peer-to-peer transmissions over an ad hoc network, where the nodes often have a different number of antennas, and the channel condition and network topology vary over time. It is important and challenging to develop efficient schemes to coordinate transmission resource sharing among a heterogeneous group of nodes over an infrastructure-free mobile ad hoc network. In this work, we propose a holistic scheduling algorithm that can adaptively select different transmission strategies based on the node types and channel conditions to effectively relieve the bottleneck effect caused by nodes with smaller antenna arrays, and avoid the transmission failure due to the violation of lower degree of freedom constraint resulted from the channel dependency. The algorithm also takes advantage of channel information to opportunistically schedule cooperative spatial multiplexed transmissions between nodes and provide special transmission support for higher priority nodes with weak channels, so that the data rate of the network can be maximized while user transmission quality requirement is supported. The performance of our algorithm is studied through extensive simulations and the results demonstrate that our algorithm is very effective in handling node heterogeneity and channel constraint, and can significantly increase the throughput while reducing the transmission delay. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Optimization Framework for XOR-Assisted Cooperative Relaying in Cellular Networks

    Publication Year: 2014 , Page(s): 979 - 991
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1289 KB) |  | HTML iconHTML  

    This work seeks to address two questions in cooperative OFDMA networks: First, how network coding based cooperative diversity can be exploited effectively when overhearing is not readily available. Second, how to realize various forms of gains available, including multi-user diversity, cooperative diversity, and network coding. The main contribution of this paper is an unifying network utility maximization framework that jointly considers relay assignment, relay strategy selection, channel assignment and power allocation. We formulate the optimization problem both with and without XOR-CD, a simple XOR-assisted cooperative diversity scheme. We show that the optimization of physical layer resource allocation with XOR-CD is equivalent to a weighted 3-set packing problem, which is NP-complete, and can be efficiently solved with provably the best approximation factor. Without XOR-CD, the problem reduces to a weighted bipartite matching problem which can be optimally solved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of an Instantaneous Packet Loss Based Vertical Handover Algorithm for Heterogeneous Wireless Networks

    Publication Year: 2014 , Page(s): 992 - 1006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1222 KB) |  | HTML iconHTML  

    For real-time applications running over hand-held mobile terminals in heterogeneous environments, efficient vertical handover (VH) algorithms are required in maintaining a seamless connectivity and an acceptable level of quality. While received signal strength-based methods have dominated this class of algorithms, we propose a thorough system analysis framework and perform rigorous analysis for packet-loss based algorithms for an interworking environment comprising the cellular network and the Wireless Local Area Network (WLAN). The basic VH algorithm analyzed here is based on the moving average of the packet loss rate and we employed both a simple packet loss and Gilbert packet loss pattern. Modifications to the analytical framework have been made by employing block-wise packet loss patterns in order to keep the computational burden within practical limits. Performance trends of call drop probabilities and WLAN usage efficiency are shown with varying system and handover thresholds, and analytical results are compared to that obtained from Monte Carlo simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Content Download in Vehicular Networks in Presence of Noisy Mobility Prediction

    Publication Year: 2014 , Page(s): 1007 - 1021
    Cited by:  Papers (1)
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1543 KB) |  | HTML iconHTML  

    Bandwidth availability in the cellular backhaul is challenged by ever-increasing demand by mobile users. Vehicular users, in particular, are likely to retrieve large quantities of data, choking the cellular infrastructure along major thoroughfares and in urban areas. It is envisioned that alternative roadside network connectivity can play an important role in offloading the cellular infrastructure. We investigate the effectiveness of vehicular networks in this task, considering that roadside units can exploit mobility prediction to decide which data they should fetch from the Internet and to schedule transmissions to vehicles. Rather than adopting a specific prediction scheme, we propose a fog-of-war model that allows us to express and account for different degrees of prediction accuracy in a simple, yet effective, manner. We show that our fog-of-war model can closely reproduce the prediction accuracy of Markovian techniques. We then provide a probabilistic graph-based representation of the system that includes the prediction information and lets us optimize content prefetching and transmission scheduling. Analytical and simulation results show that our approach to content downloading through vehicular networks can achieve a 70% offload of the cellular network. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detection of PUE Attacks in Cognitive Radio Networks Based on Signal Activity Pattern

    Publication Year: 2014 , Page(s): 1022 - 1034
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1677 KB) |  | HTML iconHTML  

    Promising to significantly improve spectrum utilization, cognitive radio networks (CRNs) have attracted a great attention in the literature. Nevertheless, a new security threat known as the primary user emulation (PUE) attack raises a great challenge to CRNs. The PUE attack is unique to CRNs and can cause severe denial of service (DoS) to CRNs. In this paper, we propose a novel PUE detection system, termed Signal activity Pattern Acquisition and Reconstruction System. Different from current solutions of PUE detection, the proposed system does not need any a priori knowledge of primary users (PUs), and has no limitation on the type of PUs that are applicable. It acquires the activity pattern of a signal through spectrum sensing, such as the ON and OFF periods of the signal. Then it reconstructs the observed signal activity pattern through a reconstruction model. By examining the reconstruction error, the proposed system can smartly distinguish a signal activity pattern of a PU from a signal activity pattern of an attacker. Numerical results show that the proposed system has excellent performance in detecting PUE attacks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed Algorithms for Energy-Efficient Even Self-Deployment in Mobile Sensor Networks

    Publication Year: 2014 , Page(s): 1035 - 1047
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1113 KB) |  | HTML iconHTML  

    Even self-deployment is one of the best strategies to deploy mobile sensors when the region of interest is unknown and manual deployment is infeasible. A widely used distributed algorithm, Lloyd`s method, can achieve even self-deployment. It however suffers from two critical issues when being used in mobile sensor networks. First, it does not consider limited sensor communication range. Second, it does not optimize sensor movement distances, and hence can lead to excessive energy consumption, a primary concern in sensor networks. This paper first formulates a locational optimization problem that achieves even deployment while it takes account of energy consumption due to sensor movement, and then proposes two iterative algorithms. The first algorithm, named Lloyd- α, reduces the movement step sizes in Lloyd`s method. It saves traveling distance while maintaining the convergence property. However, it leads to a larger number of deployment steps. The second algorithm, named Distributed Energy-Efficient self-Deployment (DEED), reduces sensor traveling distances and requires a comparable number of deployment steps as that in Lloyd`s method. This paper further proposes an intuitive method to deal with limited sensor communication range that is applicable to all three methods. Extensive simulation using NS-2 demonstrates that DEED leads to up to 54 percent less traveling distance and 46 percent less energy consumption than Lloyd`s method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fully Distributed Algorithms for Minimum Delay Routing Under Heavy Traffic

    Publication Year: 2014 , Page(s): 1048 - 1060
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1552 KB) |  | HTML iconHTML  

    We study a minimum delay routing problem in the context of distributed networks with and without partial load information. Even though a general minimum delay routing problem is NP hard, assuming uniformly distributed K source-destination (SD) pairs at random, we provide a lower bound on the average delay and demonstrate by simulation that it is tight for a certain classes of regularly deployed networks. We also show that some routing in a distributed manner is enough to achieve asymptotically optimal load balancing with high probability as K tends to infinity. In order to set such routing, however, each SD pair should know global load information, which is unrealistic for most networks. We propose novel predetermined path routing algorithms in which each SD pair chooses its routing path only among a set of predetermined paths. We then propose an efficient way of distributed construction for predetermined paths that are able to distribute traffic over a network. Our predetermined path routing algorithms work in a fully distributed manner with very limited load information or without any load information. In various network models, we demonstrate by simulation that the delay of the predetermined path routing algorithms quickly converges to that of the distributed routing with global load information. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Generation and Analysis of a Large-Scale Urban Vehicular Mobility Dataset

    Publication Year: 2014 , Page(s): 1061 - 1075
    Cited by:  Papers (1)
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2135 KB) |  | HTML iconHTML  

    The surge in vehicular network research has led, over the last few years, to the proposal of countless network solutions specifically designed for vehicular environments. A vast majority of such solutions has been evaluated by means of simulation, since experimental and analytical approaches are often impractical and intractable, respectively. The reliability of the simulative evaluation is thus paramount to the performance analysis of vehicular networks, and the first distinctive feature that has to be properly accounted for is the mobility of vehicles, i.e., network nodes. Notwithstanding the improvements that vehicular mobility modeling has undergone over the last decade, no vehicular mobility dataset is publicly available today that captures both the macroscopic and microscopic dynamics of road traffic over a large urban region. In this paper, we present a realistic synthetic dataset, covering 24 hours of car traffic in a 400-km2 region around the city of Köln, in Germany. We describe the generation process and outline how the dataset improves the traces currently employed for the simulative evaluation of vehicular networks. We also show the potential impact that such a comprehensive mobility dataset has on the network protocol performance analysis, demonstrating how incomplete representations of vehicular mobility may result in over-optimistic network connectivity and protocol performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Iterative Group Splitting Algorithm for Opportunistic Scheduling Systems

    Publication Year: 2014 , Page(s): 1076 - 1089
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1708 KB) |  | HTML iconHTML  

    An efficient feedback algorithm for opportunistic scheduling systems based on iterative group splitting is proposed in this paper. Similar to the opportunistic splitting algorithm, the proposed algorithm adjusts (or lowers) the feedback threshold during a guard period if no user sends a feedback. However, when a feedback collision occurs at any point of time, the proposed algorithm no longer updates the threshold but narrows down the user search space by dividing the users into multiple groups iteratively, whereas the opportunistic splitting algorithm keeps adjusting the threshold until a single user is found. Since the threshold is only updated when no user sends a feedback, it is shown that the proposed algorithm significantly alleviates the signaling overhead for the threshold distribution to the users by the scheduler. More importantly, the proposed algorithm requires a less number of mini-slots than the opportunistic splitting algorithm to make a user selection with a given level of scheduling outage probability or provides a higher ergodic capacity given a certain number of mini-slots. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • K NN Query Processing Methods in Mobile Ad Hoc Networks

    Publication Year: 2014 , Page(s): 1090 - 1103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1980 KB) |  | HTML iconHTML  

    In this paper, we propose two beacon-less kNN query processing methods for reducing traffic and maintaining high accuracy of the query result in mobile ad hoc networks (MANETs). In these methods, the query-issuing node first forwards a kNN query using geo-routing to the nearest node from the point specified by the query (query point). Then, the nearest node from the query point forwards the query to other nodes close to the query point, and each node receiving the query replies with the information on itself. In this process, we adopt two different approaches: the Explosion (EXP) method and the Spiral (SPI) method. In the EXP method, the nearest node from the query point floods the query to nodes within a specific circular region, and each node receiving the query replies with information on itself. In the SPI method, the nearest node from the query point forwards the query to other nodes in a spiral manner, and the node that collects a satisfactory kNN result transmits the result to the query-issuing node. Experimental results show that our proposed methods reduce traffic and achieve high accuracy of the query result, in comparison with existing methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal Multicast Capacity and DelayTradeoffs in MANETs

    Publication Year: 2014 , Page(s): 1104 - 1117
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB) |  | HTML iconHTML  

    In this paper, we give a global perspective of multicast capacity and delay analysis in Mobile Ad Hoc Networks (MANETs). Specifically, we consider four node mobility models: (1) two-dimensional i.i.d. mobility, (2) two-dimensional hybrid random walk, (3) one-dimensional i.i.d. mobility, and (4) one-dimensional hybrid random walk. Two mobility time-scales are investigated in this paper: (i) fast mobility where node mobility is at the same time-scale as data transmissions and (ii) slow mobility where node mobility is assumed to occur at a much slower time-scale than data transmissions. Given a delay constraint D, we first characterize the optimal multicast capacity for each of the eight types of mobility models, and then we develop a scheme that can achieve a capacity-delay tradeoff close to the upper bound up to a logarithmic factor. In addition, we also study heterogeneous networks with infrastructure support. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • TVR—Tall Vehicle Relaying in Vehicular Networks

    Publication Year: 2014 , Page(s): 1118 - 1131
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1991 KB) |  | HTML iconHTML  

    Vehicle-to-Vehicle (V2V) communication is a core technology for enabling safety and non-safety applications in next generation intelligent transportation systems. Due to relatively low heights of the antennas, V2V communication is often influenced by topographic features, man-made structures, and other vehicles located between the communicating vehicles. On highways, it was shown experimentally that vehicles can obstruct the line of sight (LOS) communication up to 50 percent of the time; furthermore, a single obstructing vehicle can reduce the power at the receiver by more than 20 dB. Based on both experimental measurements and simulations performed using a validated channel model, we show that the elevated position of antennas on tall vehicles improves communication performance. Tall vehicles can significantly increase the effective communication range, with an improvement of up to 50 percent in certain scenarios. Using these findings, we propose a new V2V relaying scheme called tall vehicle relaying (TVR) that takes advantage of better channel characteristics provided by tall vehicles. TVR distinguishes between tall and short vehicles and, where appropriate, chooses tall vehicles as next hop relays. We investigate TVR's system-level performance through a combination of link-level experiments and system-level simulations and show that it outperforms existing techniques. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Uplink Scheduling in Wireless Networks with Successive Interference Cancellation

    Publication Year: 2014 , Page(s): 1132 - 1144
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1456 KB) |  | HTML iconHTML  

    In this paper, we study the problem of uplink scheduling in wireless networks with successive interference cancellation (SIC). With SIC, concurrent transmissions, if properly scheduled, can be successfully decoded at a receiver. The scheduler decides: i. in which time-slot to schedule, and ii. in what order in a time-slot to decode each transmission in order to maximize the system utility and/or satisfy a system constraint. These two scheduling decisions effectively determine the rates allocated to concurrent transmissions, which in turn determine the throughput and fairness of the system. We consider several different scheduling problems in this context. The objective of the problems is to either maximize the throughput of the system or to obtain some kind of fairness among the users. We formulate and study each problem from the perspective of computational complexity. For each problem, we either propose a polynomial time algorithm, if any exists, or show that the problem is NP-hard. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • WiCop: Engineering WiFi Temporal White-Spaces for Safe Operations of Wireless Personal Area Networks in Medical Applications

    Publication Year: 2014 , Page(s): 1145 - 1158
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1505 KB) |  | HTML iconHTML  

    ZigBee and other wireless technologies operating in the (2.4GHz) ISM band are being applied in Wireless Personal Area Networks (WPAN) for many medical applications. However, these low duty cycle, low power, and low data rate medical WPANs suffer from WiFi co-channel interferences. WiFi interference can lead to longer latency and higher packet losses in WPANs, which can be particularly harmful to safety-critical applications with stringent temporal requirements, such as ElectroCardioGraphy (ECG). This paper exploits the Clear Channel Assessment (CCA) mechanism in WiFi devices and proposes a novel policing framework, WiCop, that can effectively control the temporal white-spaces between WiFi transmissions. Such temporal white-spaces can be utilized for delivering low duty cycle WPAN traffic. We have implemented and validated WiCop on SORA, a software-defined radio platform. Experimental results show that with the assistance of the proposed WiCop policing schemes, the packet reception rate of a ZigBee-based WPAN can increase by up to 116% in the presence of a heavy WiFi interferer. A case study on the medical application of WPAN ECG monitoring demonstrates that WiCop can bound ECG signal distortion within 2% even under heavy WiFi interference. An analytical framework is devised to model the CCA behavior of WiFi interferers and the performance of WPANs under WiFi interference with or without WiCop protection. The analytical results are corroborated by experiments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Mobile Computing, as proposed in this Transactions, focuses on the key technical issues related to (a) architectures, (b) support services, (c) algorithm/protocol design and analysis, (d) mobile environments, (e) mobile communication systems, (f) applications, and (g) emerging technologies.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Prasant Mohapatra
Interim Vice-Provost and CIO
Professor, Dept. Computer Science
University of California, Davis, USA
pmohapatra@ucdavis.edu