| 1. |
- Adjiashvili, David, et al.
(författare)
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Exact and Approximation Algorithms for Optimal Equipment Selection in Deploying In-Building Distributed Antenna Systems
- 2015
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Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 14:4, s. 702-713
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Tidskriftsartikel (refereegranskat)abstract
- We consider a combinatorial optimization problemin passive In-Building Distributed Antenna Systems (IB-DAS) deployment for indoor mobile broadband service. These systems have a tree topology, in which a central base station is connected to a number of antennas located at tree leaves via cables represented by the tree edges. Each inner node corresponds to a power equipment, of which the available types differ in the number of output ports and/or by power gain at the ports. This paper focuses on the equipment selection problemthat amounts to, for a given passive DAS tree topology, selecting a power equipment type for each inner node and assigning the outgoing edges of the node to the equipment ports. The performance metric is the power deviation at the antennas from the target values. We consider as objective function the minimization of either the total or the largest power deviation over all antennas. Our contributions are the development of exact pseudo-polynomial time algorithms and (additive) fully-polynomial time approximation schemes for both objectives. Numerical results are provided to illustrate the algorithms. We also extend some results to account for equipment cost.
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| 2. |
- Ahani, Ghafour, et al.
(författare)
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Optimal Content Caching and Recommendation With Age of Information
- 2024
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 23:1, s. 689-704
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Tidskriftsartikel (refereegranskat)abstract
- Content caching at the network edge is an effective way of mitigating backhaul load and improving user experience. Caching efficiency can be enhanced by content recommendation and by keeping the information fresh. By content recommendation, a requested content that is not in the cache can be alternatively satisfied by a related cached content recommended by the system. Information freshness can be quantified by age of information (AoI). This article has the following contributions. First, we address optimal scheduling of cache updates for a time-slotted system accounting for content recommendation and AoI, and to the best of our knowledge, there is no work that has jointly taken into account these aspects. Next, we rigorously prove the problem's NP-hardness. Then, we derive an integer linear formulation, by which the optimal solution can be obtained for small-scale scenarios. On the algorithmic side, our contributions include the development of an effective algorithm based on Lagrangian decomposition, and efficient algorithms for solving the resulting subproblems. Our algorithm computes a bound that can be used to evaluate the performance of any suboptimal solution. We conduct simulations to show the effectiveness of our algorithm.
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| 3. |
- Ahani, Ghafour, et al.
(författare)
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Optimal Scheduling of Age-centric Caching : Tractability and Computation
- 2022
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660 .- 2161-9875. ; 21, s. 2939-2954
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Tidskriftsartikel (refereegranskat)abstract
- The notion of age of information (AoI) has become an important performance metric in network and control systems. Information freshness, represented by AoI, naturally arises in the context of caching. We address optimal scheduling of cache updates for a time-slotted system where the contents vary in size. There is limited capacity for the cache for making updates. Each content is associated with a utility function that depends on the AoI and the time duration of absence from the cache. For this combinatorial optimization problem, we present the following contributions. First, we provide theoretical results of problem tractability. Whereas the problem is NP-hard, we prove solution tractability in polynomial time for a special case with uniform content size, by a reformulation using network flows. Second, we derive an integer linear formulation for the problem, of which the optimal solution can be obtained for small-scale scenarios. Next, via a mathematical reformulation, we derive a scalable optimization algorithm using repeated column generation. In addition, the algorithm computes a bound of global optimum, that can be used to assess the performance of any scheduling solution. Performance evaluation of large-scale scenarios demonstrates the strengths of the algorithm in comparison to a greedy schedule. Finally, we extend the applicability of our work to cyclic scheduling.
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| 4. |
- Alpcan, Tansu, et al.
(författare)
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Security Games for Vehicular Networks
- 2011
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 10:2, s. 280-290
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Tidskriftsartikel (refereegranskat)abstract
- Vehicular networks (VANETs) can be used to improve transportation security, reliability, and management. This paper investigates security aspects of VANETs within a game-theoretic framework where defensive measures are optimized with respect to threats posed by malicious attackers. The formulations are chosen to be abstract on purpose in order to maximize applicability of the models and solutions to future systems. The security games proposed for vehicular networks take as an input centrality measures computed by mapping the centrality values of the car networks to the underlying road topology. The resulting strategies help locating most valuable or vulnerable points (e.g., against jamming) in vehicular networks. Thus, optimal deployment of traffic control and security infrastructure is investigated both in the static (e.g., fixed roadside units) and dynamic cases (e. g., mobile law enforcement units). Multiple types of security games are studied under varying information availability assumptions for the players, leading to fuzzy game and fictitious play formulations in addition to classical zero-sum games. The effectiveness of the security game solutions is evaluated numerically using realistic simulation data obtained from traffic engineering systems.
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| 5. |
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| 6. |
- Biasson, A, et al.
(författare)
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A decentralized optimization framework for energy harvesting devices
- 2018
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 17:11, s. 2483-2496
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Tidskriftsartikel (refereegranskat)abstract
- Designing decentralized policies for wireless communication networks is a crucial problem, which has only been partially solved in the literature so far. In this paper, we propose a Decentralized Markov Decision Process (Dec-MDP) framework to analyze a wireless sensor network with multiple users which access a common wireless channel. We consider devices with energy harvesting capabilities, that aim at balancing the energy arrivals with the data departures and with the probability of colliding with other nodes. Over time, an access point triggers a SYNC slot, wherein it recomputes the optimal transmission parameters of the whole network, and distributes this information. Every node receives its own policy, which specifies how it should access the channel in the future, and, thereafter, proceeds in a fully decentralized fashion, with no interactions with other entities in the network. We propose a multi-layer Markov model, where an external MDP manages the jumps between SYNC slots, and an internal Dec-MDP computes the optimal policy in the short term. We numerically show that, because of the harvesting, stationary policies are suboptimal in energy harvesting scenarios, and the optimal trade-off lies between an orthogonal and a random access system.
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| 7. |
- Chaudhary, Rajat, et al.
(författare)
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SecGreen : Secrecy Ensured Power Optimization Scheme for Software-Defined Connected IoV
- 2023
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 22:4, s. 2370-2386
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Tidskriftsartikel (refereegranskat)abstract
- Software-Defined Internet of Vehicles (SD-IoV) is an emerging technology that is being used in modern intelligent transportation systems (ITS). The ultimate goal of SD-IoV is to provide seamless connectivity to the end-users with low latency and high-speed data transfer. However, due to the increase in the density of the connected IoV using an open channel, i.e., the Internet, the foremost challenges of high power consumption and secure data transfer are inevitable in such an environment. An external eavesdropper may intercept the transmitted message to access the legitimate information over the public channel, i.e., the Internet. Most of the solutions reported in the literature to tackle these issues may not be applicable in the SD-IoV environment due to high computation and communication costs. Motivated from this, in this paper, the problems of high power consumption and secure data transfer in SD-IoV are formulated using mixed-integer non-linear programming (MINLP) with associated constraints. To solve the aforementioned problem, we propose a joint power optimization and secrecy ensured scheme known as SecGreen. SecGreen has an efficient energy harvesting algorithm using simultaneous wireless information and power transfer (SWIPT) to maximize the energy efficiency. Moreover, to mitigate various security attacks, a resilient lightweight secrecy association protocol is designed between vehicle and trusted gateway node of SD-IoV so that only trusted vehicles can communicate with each other and with the nearest base stations. The secrecy association protocol uses security primitives such as- physically unclonable function (PUF), one-way hash function, and bitwise exclusive OR (XOR) operations which are suitable for energy-constraint sensors in SD-IoV. The performance of the SecGreen is compared with the existing schemes, Stable & Scalable Link Optimization (SSLO), and Secure & Energy-Efficient Blockchain-enabled (SEEB) respectively. The result shows that when the number of packets across the subchannel increases, the energy consumption increases. Also, the result shows that the proposed scheme attains 22.5% and 20.34% better energy efficiency as compared to SSLO and SEEB schemes, respectively. In addition, the SecGreen scheme achieves 37.48% and 32.15% higher throughput as compared to SSLO and SEEB schemes. The results obtained show the superior performance of the proposed SecGreen scheme in comparison to these existing competitive schemes in the literature.
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| 8. |
- Combes, Richard, et al.
(författare)
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Optimal Rate Sampling in 802.11 Systems : Theory, Design, and Implementation
- 2019
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE COMPUTER SOC. - 1536-1233 .- 1558-0660. ; 18:5, s. 1145-1158
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Tidskriftsartikel (refereegranskat)abstract
- Rate Adaptation (RA) is a fundamental mechanism in 802.11 systems. It allows transmitters to adapt the coding and modulation scheme as well as the MIMO transmission mode to the radio channel conditions, to learn and track the (mode, rate) pair providing the highest throughput. The design of RA mechanisms has been mainly driven by heuristics. In contrast, we rigorously formulate RA as an online stochastic optimization problem. We solve this problem and present G-ORS (Graphical Optimal Rate Sampling), a family of provably optimal (mode, rate) pair adaptation algorithms. Our main result is that G-ORS outperforms state-of-the-art algorithms such as MiRA and Minstrel HT as demonstrated by experiments on a 802.11n network test-bed. The design of G-ORS is supported by a theoretical analysis, where we study its performance in stationary radio environments where the successful packet transmission probabilities at the various (mode, rate) pairs do not vary over time, and in non-stationary environments where these probabilities evolve. We show that under G-ORS, the throughput loss due to the need to explore sub-optimal (mode, rate) pairs does not depend on the number of available pairs. This is a crucial advantage as evolving 802.11 standards offer an increasingly large number of (mode, rate) pairs. We illustrate the superiority of G-ORS over state-of-the-art algorithms, using both trace-driven simulations and test-bed experiments.
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| 9. |
- Curescu, C., et al.
(författare)
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A bidding algorithm for optimized utility-based resource allocation in ad hoc networks
- 2008
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 7:12, s. 1397-1414
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a scheme for bandwidth allocation in wireless ad hoc networks. The quality-of-service (QoS) levels for each end-to-end flow are expressed using a resource-utility function, and our algorithms aim to maximize aggregated utility. The shared channel is modeled as a bandwidth resource defined by maximal cliques of mutual interfering links. We propose a novel resource allocation algorithm that employs an auction mechanism in which flows are bidding for resources. The bids depend both on the flow's utility function and the intrinsically derived shadow prices. We then combine the admission control scheme with a utility-aware on-demand shortest path routing algorithm where shadow prices are used as a natural distance metric. As a baseline for evaluation, we show that the problem can be formulated as a linear programming (LP) problem. Thus, we can compare the performance of our distributed scheme to the centralized LP solution, registering results very close to the optimum. Next, we isolate the performance of price-based routing and show its advantages in hotspot scenarios, and also propose an asynchronous version that is more feasible for ad hoc environments. Further experimental evaluation compares our scheme with the state of the art derived from Kelly's utility maximization framework and shows that our approach exhibits superior performance for networks with increased mobility or less frequent allocations. © 2008 IEEE.
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| 10. |
- Deng, Shuiguang, et al.
(författare)
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Optimal Application Deployment in Resource Constrained Distributed Edges
- 2021
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 20:5, s. 1907-1923
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Tidskriftsartikel (refereegranskat)abstract
- The dramatically increasing of mobile applications make it convenient for users to complete complex tasks on their mobile devices. However, the latency brought by unstable wireless networks and the computation failures caused by constrained resources limit the development of mobile computing. A popular approach to solve this problem is to establish a mobile service provisioning system based on a mobile edge computing (MEC) paradigm. In the MEC paradigm, plenty of machines are placed at the edge of the network so that the performance of applications can be optimized by using the involved microservice instances deployed on them. In this paper, we explore the deployment problem of microserivce-based applications in the MEC environment and propose an approach to help to optimize the cost of application deployment with the constraints of resources and the requirement of performance. We conduct a series of experiments to evaluate the performance of our approach. The result shows that our approach can improve the average response time of mobile services.
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| 11. |
- Eriksson, Emil, et al.
(författare)
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Predictive Distributed Visual Analysis for Video in Wireless Sensor Networks
- 2016
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Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 15:7, s. 1743-1756
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of performing distributed visual analysis for a video sequence in a visual sensor network that contains sensor nodes dedicated to processing. Visual analysis requires the detection and extraction of visual features from the images, and thus the time to complete the analysis depends on the number and on the spatial distribution of the features, both of which are unknown before performing the detection. In this paper, we formulate the minimization of the time needed to complete the distributed visual analysis for a video sequence subject to a mean average precision requirement as a stochastic optimization problem. We propose a solution based on two composite predictors that reconstruct randomly missing data, on quantile-based linear approximation of feature distribution and on time series analysis methods. The composite predictors allow us to compute an approximate optimal solution through linear programming. We use two surveillance video traces to evaluate the proposed algorithms, and show that prediction is essential for minimizing the completion time, even if the wireless channel conditions vary and introduce significant randomness. The results show that the last value predictor together with regular quantile-based distribution approximation provide a low complexity solution with very good performance.
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| 12. |
- Farag, Hossam, et al.
(författare)
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Distributed Backlog-Aware Protocol for Heterogeneous D2D Communication-Assisted Wireless Sensor Networks
- 2024
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 23:5, s. 3981-3992
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Tidskriftsartikel (refereegranskat)abstract
- Age of Information (AoI) and delay are crucial performance metrics for Industrial Internet of Things (IIoT) applications not only to perform seamless actuation and control actions but also to enable self-organized and re-configurable manufacturing systems. A challenging task in heterogeneous IIoT networks is to minimize the AoI while maintaining a predefined delay constraint. In this work, we consider a Device-to-Device (D2D)-based heterogeneous IIoT network that supports two types of traffic flows, namely AoI-sensitive flow and delay-sensitive flow. First, we introduce a distributed backlog-aware random access protocol that allows the AoI-sensitive nodes to opportunistically access the channel based on the queue occupancy of the delay-sensitive node. Then, we develop an analytical framework to evaluate the average delay and the average AoI, and formulate an optimization problem to minimize the AoI under a given delay constraint. Finally, we provide numerical results to demonstrate the impact of different network parameters on the performance in terms of the average delay and the average AoI. We also give numerical solutions of the optimal parameters that minimize the AoI subject to a defined delay constraint.
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| 13. |
- Fiedler, Markus, et al.
(författare)
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Estimating performance of mobile services from comparative output-input analysis of end-to-end throughput
- 2013
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 12:9, s. 1761-1773
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Tidskriftsartikel (refereegranskat)abstract
- Mobile devices with ever-increasing functionality and the ubiquitous availability of wireless communication networks are driving forces behind innovative mobile applications enriching our daily life. One of the performance measures for a successful application deployment is the ability to support application-data flows by heterogeneous networks within certain delay boundaries. However, the quantitative impact of this measure is unknown and practically infeasible to determine at real-time due to the mobile device resource constraints. We research practical methods for measurement-based performance evaluation of heterogeneous data communication networks that support mobile application-data flows. We apply the lightweight Comparative Output-Input Analysis (COIA) method estimating an additional delay based on an observation interval of interest (e.g., one second) induced on the flow. An additional delay is the amount of delay that exceeds non-avoidable, minimal end-to-end delay caused by the networks propagation, serialization and transmission. We propose five COIA methods to estimate additional delay and we validate their accuracy with measurements obtained from the existing healthcare and multimedia streaming applications. Despite their simplicity, our methods prove to be accurate in relation to an observation interval of interest, and robust under a variety of network conditions. The methods offer novel insights into application-data delays with regards to the performance of heterogeneous data communication networks.
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| 14. |
- Fiore, Marco, et al.
(författare)
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Discovery and Verification of Neighbor Positions in Mobile Ad Hoc Networks
- 2013
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 12:2, s. 289-303
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Tidskriftsartikel (refereegranskat)abstract
- A growing number of ad hoc networking protocols and location-aware services require that mobile nodes learn the position of their neighbors. However, such a process can be easily abused or disrupted by adversarial nodes. In absence of a priori trusted nodes, the discovery and verification of neighbor positions presents challenges that have been scarcely investigated in the literature. In this paper, we address this open issue by proposing a fully distributed cooperative solution that is robust against independent and colluding adversaries, and can be impaired only by an overwhelming presence of adversaries. Results show that our protocol can thwart more than 99 percent of the attacks under the best possible conditions for the adversaries, with minimal false positive rates.
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| 15. |
- Fotouhi, Hossein, et al.
(författare)
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Reliable and fast hand-offs in low-power wireless networks
- 2014
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 13:11, s. 2620-2633
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Tidskriftsartikel (refereegranskat)abstract
- Hand-off (or hand-over), the process where mobile nodes select the best access point available to transfer data, has been well studied in wireless networks. The performance of a hand-off process depends on the specific characteristics of the wireless links. In the case of low-power wireless networks, hand-off decisions must be carefully taken by considering the unique properties of inexpensive low-power radios. This paper addresses the design, implementation and evaluation of smart-HOP, a hand-off mechanism tailored for low-power wireless networks. This work has three main contributions. First, it formulates the hard hand-off process for low-power networks (such as typical wireless sensor networks - WSNs) with a probabilistic model, to investigate the impact of the most relevant channel parameters through an analytical approach. Second, it confirms the probabilistic model through simulation and further elaborates on the impact of several hand-off parameters. Third, it fine-tunes the most relevant hand-off parameters via an extended set of experiments, in a realistic experimental scenario. The evaluation shows that smart-HOP performs well in the transitional region while achieving more than 98 percent relative delivery ratio and hand-off delays in the order of a few tens of a milliseconds.
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| 16. |
- Fuchs, Adel, et al.
(författare)
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IoT and HIPs Opportunistic Mode
- 2021
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE COMPUTER SOC. - 1536-1233 .- 1558-0660. ; 20:4, s. 1434-1448
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Tidskriftsartikel (refereegranskat)abstract
- Key sharing has always been a complex issue. It became even more challenging for the Internet of Things (IoT), where a trusted third party for global management rarely exists. With authentication and confidentiality lacking, things resort to a leap of faith (LoF) paradigm where it is assumed that no attacker is present during the initial configuration. In this paper we focus on the Host Identity Protocol (HIP), specifically designed to provide mobility and multihoming capabilities. Although HIP is normally based on many strict security mechanisms (e.g., DNSSEC), it also provides a better than nothing opportunistic mode, based on the LoF paradigm, which is to be used when other more trusted mechanisms are not available. In this paper, we analyze different MiTM attacks which might occur under this opportunistic mode. Taking advantage of HIPs multihoming capabilities, we propose two key spraying techniques which strengthen the opportunistic modes security. The first technique spreads the four key-exchange messages among different networks, while the second spreads fractions of one of those messages. Evaluation of these techniques is provided, demonstrating the major benefit of our proposal.
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| 17. |
- Galletta, Antonino, et al.
(författare)
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Investigating the Applicability of Nested Secret Share for Drone Fleet Photo Storage
- 2024
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Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 23:4, s. 2671-2683
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Tidskriftsartikel (refereegranskat)abstract
- Military drones can be used for surveillance or spying on enemies. They, however, can be either destroyed or captured, therefore photos contained inside them can be lost or revealed to the attacker. A possible solution to solve such a problem is to adopt Secret Share (SS) techniques to split photos into several sections/chunks and distribute them among a fleet of drones. The advantages of using such a technique are two folds. First, no single drone contains any photo in its entirety; thus even when a drone is captured, the attacker cannot discover any photos. Second, the storage requirements of drones can be simplified, and thus cheaper drones can be produced for such missions. In this scenario, a fleet of drones consists of t+r drones, where t (threshold) is the minimum number of drones required to reconstruct the photos, and r (redundancy) is the maximum number of lost drones the system can tolerate. The optimal configuration of t+r is a formidable task. This configuration is typically rigid and hard to modify in order to fit the requirements of specific missions. In this work, we addressed such an issue and proposed the adoption of a flexible Nested Secret Share (NSS) technique. In our experiments, we compared two of the major SS algorithms (Shamir's schema and the Redundant Residue Number System (RRNS)) with their Two-Level NSS (2NSS) variants to store/retrieve photos. Results showed that Redundant Residue Number System (RRNS) is more suitable for a drone fleet scenario.
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| 18. |
- He, Qing, et al.
(författare)
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Maximum Link Activation with Cooperative Transmission and Interference Cancellation in Wireless Networks
- 2017
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 16:2, s. 408-421
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Tidskriftsartikel (refereegranskat)abstract
- We address the maximum link activation problem in wireless networks with new features, namely when the transmitters can perform cooperative transmission, and the receivers are able to perform successive interference cancellation. In this new problem setting, which transmitters should transmit and to whom, as well as the optimal cancellation patterns at the receivers, are strongly intertwined. We present contributions along three lines. First, we provide a thorough tractability analysis, proving the NP-hardness as well as identifying tractable cases. Second, for benchmarking purposes, we deploy integer linear programming for achieving global optimum using off-theshelf optimization methods. Third, to overcome the scalability issue of integer programming, we design a sub-optimal but efficient optimization algorithm for the problem in its general form, by embedding maximum-weighted bipartite matching into local search. Numerical results are presented for performance evaluation, to validate the benefit of cooperative transmission and interference cancellation for maximum link activation and to demonstrate the effectiveness of the proposed algorithm.
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| 19. |
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| 20. |
- Helgason, Ólafur, et al.
(författare)
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Opportunistic Communication and Human Mobility
- 2014
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Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 13:7, s. 1597-1610
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Tidskriftsartikel (refereegranskat)abstract
- Many mobility models currently used for evaluating wireless communication systems have weak resemblance to reality and there is a lack of understanding on which characteristics of human mobility affect system performance. In particular, most current mobility models assume a free flow of nodes and do not consider how mobility is affected by interactions with other persons and with the physical environment. They also assume a closed system, not considering the effect of node arrival and departure. The structure of space in which the mobility occurs is either not considered at all, or only in a limited way. In this work, we address human pedestrian mobility for evaluation of wireless communication to determine which of the aforementioned aspects need to be captured and to what level of detail. We focus on opportunistic communication in the form of ad-hoc and delay-tolerant networks. For the evaluation, we use mobility models from the field of transportation and urban planning that are used for designing and dimensioning public spaces for comfort and safety of pedestrians in rush hour and emergency evacuation. The models capture micro-mobility of pedestrians better than most mobility models used in mobile networking since the application domain requires realistic representation of node interactions with the physical environment and with other nodes. Our results show that the free flow assumption used in most models does not have a significant performance impact. We also conclude that performance is not very sensitive to accurate estimation of the probability distributions of mobility parameters such as speed and arrival process. Our results, however, suggest that it is important to capture the scenario and space in which mobility occurs since these may affect performance significantly.
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| 21. |
- Jang, Insun, et al.
(författare)
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A Proxy-Based Collaboration System to Minimize Content Download Time and Energy Consumption
- 2017
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 16:8, s. 2105-2117
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Tidskriftsartikel (refereegranskat)abstract
- Mobile collaborative community (MCC) is an emerging technology that allows multiple mobile nodes (MNs) to perform a resource intensive task, such as large content download, in a cooperative manner. In this paper, we introduce a proxy-based collaboration system for the MCC where a content proxy (CProxy) determines the amount of chunks and the sharing order scheduled to each MN, and the received chunks are shared among MNs via Wi-Fi Direct. We formulate a multi-objective optimization problem to minimize both the collaborative content download time and the energy consumption in an MCC, and propose a heuristic algorithm for solving the optimization problem. Extensive simulations are carried out to evaluate the effects of the number of MNs, the wireless bandwidth, the content size, and dynamic channel conditions on the content download time and the energy consumption. Our results demonstrate that the proposed algorithm can achieve near-optimal performance and significantly reduce the content download time and has an energy consumption comparable to that of other algorithms.
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| 22. |
- Josilo, Sladana, et al.
(författare)
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Selfish Decentralized Computation Offloading for Mobile Cloud Computing in Dense Wireless Networks
- 2019
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE COMPUTER SOC. - 1536-1233 .- 1558-0660. ; 18:1, s. 207-220
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Tidskriftsartikel (refereegranskat)abstract
- Offloading computation to a mobile cloud is a promising solution to augment the computation capabilities of mobile devices. In this paper, we consider selfish mobile devices in a dense wireless network, in which individual mobile devices can offload computations through multiple access points or through the base station to a mobile cloud so as to minimize their computation costs. We provide a game theoretical analysis of the problem, prove the existence of pure strategy Nash equilibria, and provide an efficient decentralized algorithm for computing an equilibrium. For the case when the cloud computing resources scale with the number of mobile devices, we show that all improvement paths are finite. Furthermore, we provide an upper bound on the price of anarchy of the game, which serves as an upper bound on the approximation ratio of the proposed decentralized algorithms. We use simulations to evaluate the time complexity of computing Nash equilibria and to provide insights into the price of anarchy of the game under realistic scenarios. Our results show that the equilibrium cost may be close to optimal, and the convergence time is almost linear in the number of mobile devices.
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| 23. |
- Kaltiokallio, Ossi, et al.
(författare)
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A Novel Bayesian Filter for RSS-Based Device-Free Localization and Tracking
- 2021
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Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 20:3, s. 780-795
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Tidskriftsartikel (refereegranskat)abstract
- Received signal strength based device-free localization applications utilize a model that relates the measurements to position of the wireless sensors and person, and the underlying inverse problem is solved either using an imaging method or a nonlinear Bayesian filter. In this paper, it is shown that the Bayesian filters nearly reach the posterior Cramer-Rao bound and they are superior with respect to imaging approaches in terms of localization accuracy because the measurements are directly related to position of the person. However, Bayesian filters are known to suffer from divergence issues and in this paper, the problem is addressed by introducing a novel Bayesian filter. The developed filter augments the measurement model of a Bayesian filter with position estimates from an imaging approach. This bounds the filter's measurement residuals by the position errors of the imaging approach and as an outcome, the developed filter has robustness of an imaging method and tracking accuracy of a Bayesian filter. The filter is demonstrated to achieve a localization error of 0:11 m in a 75 m(2) open indoor deployment and an error of 0:29 m in a 82 m(2) apartment experiment, decreasing the localization error by 30-48 percent with respect to a state-of-the-art imaging method.
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| 24. |
- Khodaei, Mohammad, et al.
(författare)
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Scalable & Resilient Vehicle-Centric Certificate Revocation List Distribution in Vehicular Communication Systems
- 2021
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 20:7, s. 2473-2489
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Tidskriftsartikel (refereegranskat)abstract
- In spite of progress in securing Vehicular Communication (VC) systems, there is no consensus on how to distribute Certificate Revocation Lists (CRLs). The main challenges lie exactly in (i) crafting an efficient and timely distribution of CRLs for numerous anonymous credentials, pseudonyms, (ii) maintaining strong privacy for vehicles prior to revocation events, even with honest-but-curious system entities, (iii) and catering to computation and communication constraints of on-board units with intermittent connectivity to the infrastructure. Relying on peers to distribute the CRLs is a double-edged sword: abusive peers could "pollute" the process, thus degrading the timely CRLs distribution. In this paper, we propose a vehicle-centric solution that addresses all these challenges and thus closes a gap in the literature. Our scheme radically reduces CRL distribution overhead: each vehicle receives CRLs corresponding only to its region of operation and its actual trip duration. Moreover, a "fingerprint" of CRL 'pieces' is attached to a subset of (verifiable) pseudonyms for fast CRL 'piece' validation (while mitigating resource depletion attacks abusing the CRL distribution). Our experimental evaluation shows that our scheme is efficient, scalable, dependable, and practical: with no more than 25 KB/s of traffic load, the latest CRL can be delivered to 95% of the vehicles in a region (15 x 15 KM) within 15s, i.e., more than 40 times faster than the state-of-the-art. Overall, our scheme is a comprehensive solution that complements standards and can catalyze the deployment of secure and privacy-protecting VC systems.
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| 25. |
- Kouyoumdjieva, Sylvia T., et al.
(författare)
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Impact of Duty Cycling on Opportunistic Communication
- 2016
-
Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 15:7, s. 1686-1698
-
Tidskriftsartikel (refereegranskat)abstract
- A major challenge in mobile wireless devices for opportunistic networks is to decrease the energy consumption. The decrease should not come at a cost of reduced application throughput (i.e. goodput). This work evaluates the potential performance gains for mobile nodes that adopt duty cycling in an opportunistic context. The paper presents an analytical framework for evaluating goodput and energy consumption of nodes based on a probabilistic estimation of effective contact durations, and it validates this framework on a mobility scenario. The study shows that both goodput and energy consumption depend strongly on the distribution of listening durations, and that goodput is independent of the contact rate among nodes. This work also includes extensive trace-driven simulations and demonstrates that duty cycling considerably improves the performance of opportunistic networks by decreasing the energy consumption without significantly affecting the goodput.
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| 26. |
- Kumar Singh, Suneet, et al.
(författare)
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Hybrid P4 Programmable Pipelines for 5G gNodeB and User Plane Functions
- 2022
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; , s. 1-18
-
Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on hybrid pipeline designs for User Plane Function and next-generation NodeB leveraging target-specific features and an insightful discussion of P4 and target challenges and limitations. The entire or disaggregated UPF runs on P4 targets and allocates packet processing data paths in P4 hardware or DPDK/x86 software based on flow characteristics (e.g., heavy hitters) and QoS requirements (e.g., low-latency slices). For the hybrid gNodeB, most packet processing is executed in commodity Tofino hardware, while unsupported functions such as Automatic Repeat Request and cryptography are performed in DPDK/x86. We show that our hybrid UPF improves the scalability by 18× and reduces latency up to 50%. The results also suggest that careful traffic allocation to pipeline targets is required to optimize each target's strength and avoid processing delays. Finally, we demonstrate a QoS-oriented application of the hybrid UPF and present gNodeB buffer service benchmarks.
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| 27. |
- Lau, Chun Pong, et al.
(författare)
-
An Efficient Content Delivery System for 5G CRAN Employing Realistic man Mobility
- 2019
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE COMPUTER SOC. - 1536-1233 .- 1558-0660. ; 18:4, s. 742-756
-
Tidskriftsartikel (refereegranskat)abstract
- Today's modern communication technologies such as cloud radio access and software defined networks are key candidate technologies for enabling 5G networks as they incorporate intelligence for data-driven networks. Traditional content caching in the last mile access point has shown a reduction in the core network traffic. However, the radio access network still does not fully leverage such solution. Transmitting duplicate copies of contents to mobile users consumes valuable radio spectrum resources and unnecessary base station energy. To overcome these challenges, we propose huManmObility-based cOntent Distribution (MOOD) system. MOOD exploits urban scale users' mobility to allocate radio resources spatially and temporally for content delivery. Our approach uses the broadcast nature of wireless communication to reduce the number of duplicated transmissions of contents in the radio access network for conserving radio resources and energy. Furthermore, a human activity model is presented and statistically analyzed for simulating people daily routines. The proposed approach is evaluated via simulations and compared with a generic broadcast strategy in an actual existing deployment of base stations as well as a smaller cells environment, which is a trending deployment strategy in future 5G networks. MOOD achieves 15.2 and 25.4 percent of performance improvement in the actual and small-cell deployment, respectively.
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| 28. |
- Lee, Kyunghan, et al.
(författare)
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Max Contribution : An Online Approximation of Optimal Resource Allocation in Delay Tolerant Networks
- 2015
-
Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 14:3, s. 592-605
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a joint optimization of link scheduling, routing and replication for delay-tolerant networks (DTNs) has been studied. The optimization problems for resource allocation in DTNs are typically solved using dynamic programming which requires knowledge of future events such as meeting schedules and durations. This paper defines a new notion of approximation to the optimality for DTNs, called snapshot approximation where nodes are not clairvoyant, i.e., not looking ahead into future events, and thus decisions are made using only contemporarily available knowledges. Unfortunately, the snapshot approximation still requires solving an NP-hard problem of maximum weighted independent set (MWIS) and a global knowledge of who currently owns a copy and what their delivery probabilities are. This paper proposes an algorithm, Max-Contribution (MC) that approximates MWIS problem with a greedy method and its distributed online approximation algorithm, Distributed Max-Contribution (DMC) that performs scheduling, routing and replication based only on locally and contemporarily available information. Through extensive simulations based on real GPS traces tracking over 4,000 taxies and 500 taxies for about 30 days and 25 days in two different large cities, DMC is verified to perform closely to MC and outperform existing heuristically engineered resource allocation algorithms for DTNs.
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| 29. |
- Liu, Xiuming, et al.
(författare)
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Secure Information Fusion using Local Posterior for Distributed Cyber-Physical Systems
- 2020
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 20:5, s. 2041-2054
-
Tidskriftsartikel (refereegranskat)abstract
- In modern distributed cyber-physical systems (CPS), information fusion often plays a key role in automate and self-adaptive decision making process. However, given the heterogeneous and distributed nature of modern CPSs, it is a great challenge to operate CPSs with the compromised data integrity and unreliable communication links. In this paper, we study the distributed state estimation problem under the false data injection attack (FDIA) with probabilistic communication networks. We propose an integrated "detection + fusion" solution, which is based on the Kullback-Leibler divergences (KLD) between local posteriors and therefore does not require the exchange of raw sensor data. For the FDIA detection step, the KLDs are used to cluster nodes in the probability space and to partition the space into secure and insecure subspaces. By approximating the distribution of the KLDs with a general chi(2) distribution and calculating its tail probability, we provide an analysis of the detection error rate. For the information fusion step, we discuss the potential risk of double counting the shared prior information in the KLD-based consensus formulation method. We show that if the local posteriors are updated from the shared prior, the increased number of neighbouring nodes will lead to the diminished information gain. To overcome this problem, we propose a near-optimal distributed information fusion solution with properly weighted prior and data likelihood. Finally, we present simulation results for the integrated solution. We discuss the impact of network connectivity on the empirical detection error rate and the accuracy of state estimation.
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| 30. |
- Louis, Sibomana, et al.
(författare)
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A Framework for Packet Delay Analysis of Point-to-Multipoint Underlay Cognitive Radio Networks
- 2017
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 16:9, s. 2408-2421
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a queueing analytical framework for the performance evaluation of the secondary user (SU) packet transmission with service differentiation in a point-to-multipoint underlay cognitive radio network. The transmit power of the SU transmitter is subject to the joint outage constraint imposed by the primary user receivers (PU-Rxs) and the SU maximum transmit power limit. The analysis considers a queueing model for secondary traffic with multiple classes, and different types of arrival and service processes under a non-preemptive priority service discipline. The SU quality of service (QoS) is characterized by a packet timeout threshold and target bit error rate. Given these settings, analytical expressions of the packet timeout probability and average transmission time are derived for opportunistic and multicast scheduling. Moreover, expressions of the average packet waiting time in the queue and the total time in the system for each class of traffic are obtained. Numerical examples are provided to illustrate the secondary network performance with respect to various parameters such as number of PU-Rxs and SU receivers, SU packet arrival process, QoS requirements, and the impact of interference from the primary network to the secondary network.
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| 31. |
- Lutu, A., et al.
(författare)
-
Measuring Roaming in Europe : Infrastructure and Implications on Users QoE
- 2021
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 21:10, s. 3687-3699
-
Tidskriftsartikel (refereegranskat)abstract
- "Roam like Home" is the initiative of the European Commission to end the levy of extra charges when roaming within the European region. As a result, people can use data services more freely across Europe. However, the implications of roaming solutions on network performance have not been carefully examined yet. This paper provides an in-depth characterization of the implications of international data roaming within Europe. We build a unique roaming measurement platform using 16 different mobile networks deployed in 6 countries across Europe. Using this platform, we measure different aspects of international roaming in 4G networks in Europe, including mobile network configuration, performance characteristics, and quality of experience. We find that operators adopt a common approach to implement roaming called Home-routed roaming. This results in additional latency penalties of 60 ms or more, depending on geographical distance. This leads to worse browsing performance, with an increase in the metrics related to Quality of Experience (QoE) of users (Page Load time and Speed Index) in the order of 15-20%. We further analyze the impact of latency on QoE metrics in isolation and find that the penalty imposed by Home Routing leads to degradation on QoE metrics up to 150% in case of intercontinental roaming. We make our dataset public to allow reproducing the results.
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| 32. |
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| 33. |
- Megas, Vasileios, et al.
(författare)
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A Combined Topology Formation and Rate Allocation Algorithm for Aeronautical Ad Hoc Networks
- 2022
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; , s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- This paper aims to address the problem of providing internet connectivity to aircraft flying above the ocean without using satellite connectivity given that there is no ground network infrastructure in the ocean. Is it possible to guarantee a minimum flow rate to each aircraft flying over an ocean by forming an aeronautical ad hoc network and connecting that network to internet via a set of limited number of ground base stations at the coast as anchor points? We formulated the problem as mixed-integer-linear programming (MILP) to maximize the number of aircraft with flow data rate above a certain threshold. Since this is a multi-commodity flow problem and at least NP-complete, we propose a two-phase heuristic algorithm to efficiently form topology and assign flows to each aircraft by maximizing the minimum flow. The performance of the heuristic algorithm is evaluated over the North Atlantic Corridor, heuristic performs only 8% less than the optimal result with low densities. In high network densities, the connectivity percentage changes from 70% to 40% under 75 Mbps data rate threshold. Furthermore, the connectivity percentage is investigated for different network parameters such as altitude and compared with upper and lower bounds and a baseline algorithm.
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| 34. |
- Minovski, Dimitar, 1990-, et al.
(författare)
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Throughput Prediction using Machine Learning in LTE and 5G Networks
- 2023
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 22:3, s. 1825-1840
-
Tidskriftsartikel (refereegranskat)abstract
- The emergence of novel cellular network technologies, within 5G, are envisioned as key enablers of a new set of use-cases, including industrial automation, intelligent transportation, and tactile internet. The critical nature of the traffic requirements ranges from ultra-reliable communications, massive connectivity, and enhanced mobile broadband. Thus, the growing research on cellular network monitoring and prediction aims for ensuring a satisfied user-base and fulfillment of service level agreements. The scope of this study is to develop an approach for predicting the cellular link throughput of end-users, with a goal to benchmark the performance of network slices. First, we report and analyze a measurement study involving real-life cases, such as driving in urban, sub-urban, and rural areas, as well as tests in large crowded areas. Second, we develop machine learning models using lower-layer metrics, describing the radio environment, to predict the available throughput. The models are initially validated on the LTE network and then applied to a non-standalone 5G network. Finally, we suggest scaling the proposed model into the future standalone 5G network. We have achieved 93% and 84% R^2 accuracy, with 0.06 and 0.17 mean squared error, in predicting the end-user's throughput in LTE and non-standalone 5G network, respectively.
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| 35. |
- Mitra, Karan, et al.
(författare)
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Context-Aware QoE Modelling, Measurement and Prediction in Mobile Computing Systems
- 2015
-
Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 14:5, s. 920-936
-
Tidskriftsartikel (refereegranskat)abstract
- Quality of Experience (QoE) as an aggregate of Quality of Service (QoS) and human user-related metrics will be the key success factor for current and future mobile computing systems. QoE measurement and prediction are complex tasks as they may involve a large parameter space such as location, delay, jitter, packet loss and user satisfaction just to name a few. These tasks necessitate the development of practical context-aware QoE models that efficiently determine relationships between user context and QoE parameters. In this paper, we propose, develop and validate a novel decision-theoretic approach called CaQoEM for QoE modelling, measurement and prediction. We address the challenge of QoE measurement and prediction where each QoE parameter can be measured on a different scale and may involve different units of measurement. CaQoEM is context-aware and uses Bayesian networks and utility theory to measure and predict users' QoE under uncertainty. We validate CaQoEM using extensive experimentation, user studies and simulations. The results soundly demonstrate that CaQoEM correctly measures range-defined QoE using a bipolar scale. For QoE prediction, an overall accuracy of 98.93\% was achieved using 10-fold cross validation in multiple diverse network conditions such as vertical handoffs, wireless signal fading and wireless network congestion.
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| 36. |
- Moothedath, Vishnu Narayanan, et al.
(författare)
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Energy Efficient Sampling Policies for Edge Computing Feedback Systems
- 2022
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; , s. 1-1
-
Tidskriftsartikel (refereegranskat)abstract
- We study the problem of finding efficient sampling policies in an edge-based feedback system, where sensor samples are offloaded to a back-end server that processes them and generates feedback to a user. Sampling the system at maximum frequency results in the detection of events of interest with minimum delay but incurs higher energy costs due to the communication and processing of redundant samples. On the other hand, lower sampling frequency results in higher delay in detecting the event, thus increasing the idle energy usage and degrading the quality of experience. We quantify this trade-off as a weighted function between the number of samples and the sampling interval. We solve the minimisation problem for exponential and Rayleigh distributions, for the random time to the event of interest. We prove the convexity of the objective functions by using novel techniques, which can be of independent interest elsewhere. We argue that adding an initial offset to the periodic sampling can further reduce the energy consumption and jointly compute the optimum offset and sampling interval. We apply our framework to two practically relevant applications and show energy savings of up to 36% when compared to an existing periodic scheme.
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| 37. |
- Park, Pangun, 1980-, et al.
(författare)
-
Breath: an Adaptive Protocol for Industrial Control Applications using Wireless Sensor Networks
- 2011
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE. - 1536-1233 .- 1558-0660. ; 10:6, s. 821-838
-
Tidskriftsartikel (refereegranskat)abstract
- An energy-efficient, reliable and timely data transmission is essential for Wireless Sensor Networks (WSNs) employed in scenarios where plant information must be available for control applications. To reach a maximum efficiency, cross-layer interaction is a major design paradigm to exploit the complex interaction among the layers of the protocol stack. This is challenging because latency, reliability, and energy are at odds, and resource-constrained nodes support only simple algorithms. In this paper, the novel protocol Breath is proposed for control applications. Breath is designed for WSNs where nodes attached to plants must transmit information via multihop routing to a sink. Breath ensures a desired packet delivery and delay probabilities while minimizing the energy consumption of the network. The protocol is based on randomized routing, medium access control, and duty-cycling jointly optimized for energy efficiency. The design approach relies on a constrained optimization problem, whereby the objective function is the energy consumption and the constraints are the packet reliability and delay. The challenging part is the modeling of the interactions among the layers by simple expressions of adequate accuracy, which are then used for the optimization by in-network processing. The optimal working point of the protocol is achieved by a simple algorithm, which adapts to traffic variations and channel conditions with negligible overhead. The protocol has been implemented and experimentally evaluated on a testbed with off-the-shelf wireless sensor nodes, and it has been compared with a standard IEEE 802.15.4 solution. Analytical and experimental results show that Breath is tunable and meets reliability and delay requirements. Breath exhibits a good distribution of the working load, thus ensuring a long lifetime of the network. Therefore, Breath is a good candidate for efficient, reliable, and timely data gathering for control applications.
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| 38. |
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| 39. |
- Qi, Nan, et al.
(författare)
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A Task-Driven Sequential Overlapping Coalition Formation Game for Resource Allocation in Heterogeneous UAV Networks
- 2023
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 22:8, s. 4439-4455
-
Tidskriftsartikel (refereegranskat)abstract
- A heterogeneous unmanned aerial vehicle (UAV) network where UAVs carrying different resources form coalition and cooperatively carry out tasks is of crucial importance for fulfilling diverse tasks. However, the existing coalition formation (CF) game model only optimizes the composition of UAVs in a single coalition, which results in disjoined coalitions. In order to tackle this issue, a sequential overlapping coalition formation (OCF) game is proposed by considering the overlapping and complementary relations of resource properties and the task execution order. Moreover, different from the Pareto and selfish orders, a bilateral mutual benefit transfer (BMBT) order is proposed to optimize the cooperative task resource allocation through partial cooperation among overlapping coalition members. Furthermore, using the preference relation between UAVs carrying resources and tasks requiring the same type of resource, a preference gravity-guided tabu search (PGG-TS) algorithm is developed to obtain a stable coalition structure. Numerical results verify that the proposed PGG-TS algorithm increases the average utility of tasks by 12.5% and 38.5% compared with the split-merge preferred OCF algorithm and non-overlapping CF algorithm, respectively. The utility of the proposed BMBT order increases by 25.1% and 34.3% compared with selfish and Pareto orders, respectively.
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| 40. |
- Rabitsch, Alexander, et al.
(författare)
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Utilizing Multi-Connectivity to Reduce Latency and Enhance Availability for Vehicle to Infrastructure Communication
- 2022
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 21:5, s. 1874-1891
-
Tidskriftsartikel (refereegranskat)abstract
- Cooperative Intelligent Transport Systems (C-ITS) enable information to be shared wirelessly between vehicles and infrastructure in order to improve transport safety and efficiency. Delivering C-ITS services using existing cellular networks offers both financial and technological advantages, not least since these networks already offer many of the features needed by C-ITS, and since many vehicles on our roads are already connected to cellular networks. Still, C-ITS pose stringent requirements in terms of availability and latency on the underlying communication system; requirements that will be hard to meet for currently deployed 3G, LTE, and early-generation 5G systems. Through a series of experiments in the MONROE testbed (a cross-national, mobile broadband testbed), the present study demonstrates how cellular multi-access selection algorithms can provide close to 100% availability, and significantly reduce C-ITS transaction times. The study also proposes and evaluates a number of low-complexity, low-overhead single-access selection algorithms, and shows that it is possible to design such solutions so that they offer transaction times and availability levels that rival those of multi-access solutions.
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| 41. |
- Rossi, Michele, et al.
(författare)
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SYNAPSE plus plus : Code Dissemination in Wireless Sensor Networks Using Fountain Codes
- 2010
-
Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 9:12, s. 1749-1765
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents SYNAPSE++, a system for over the air reprogramming of wireless sensor networks (WSNs). In contrast to previous solutions, which implement plain negative acknowledgment-based ARQ strategies, SYNAPSE++ adopts a more sophisticated error recovery approach exploiting rateless fountain codes (FCs). This allows it to scale considerably better in dense networks and to better cope with noisy environments. In order to speed up the decoding process and decrease its computational complexity, we engineered the FC encoding distribution through an original genetic optimization approach. Furthermore, novel channel access and pipelining techniques have been jointly designed so as to fully exploit the benefits of fountain codes, mitigate the hidden terminal problem and reduce the number of collisions. All of this makes it possible for SYNAPSE++ to recover data over multiple hops through overhearing by limiting, as much as possible, the number of explicit retransmissions. We finally created new bootloader and memory management modules so that SYNAPSE++ could disseminate and load program images written using any language. At the end of this paper, the effectiveness of SYNAPSE++ is demonstrated through experimental results over actual multihop deployments, and its performance is compared with that of Deluge, the de facto standard protocol for code dissemination in WSNs. The TinyOS 2 code of SYNAPSE++ is available at http://dgt.dei.unipd.it/download.
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| 42. |
- Shin, Won-Yong, et al.
(författare)
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Opportunistic Network Decoupling with Virtual Full-Duplex Operation in Multi-Source Interfering Relay Networks
- 2017
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE Computer Society. - 1536-1233 .- 1558-0660. ; 16:8, s. 2321-2333
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce a new achievability scheme, termed opportunistic network decoupling (OND), operating in virtual full-duplex mode. In the scheme, a novel relay scheduling strategy is utilized in the K x N x K channel with interfering relays, consisting of K source-destination pairs and N half-duplex relays in-between them. A subset of relays using alternate relaying is opportunistically selected in terms of producing the minimum total interference level, thereby resulting in network decoupling. As our main result, it is shown that under a certain relay scaling condition, the OND protocol achieves K degrees of freedom even in the presence of interfering links among relays. Numerical evaluation is also shown to validate the performance of the proposed OND. Our protocol basically operates in a fully distributed fashion along with local channel state information, thereby resulting in relatively easy implementation.
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| 43. |
- Tütüncüoğlu, Feridun, et al.
(författare)
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Joint Resource Management and Pricing for Task Offloading in Serverless Edge Computing
- 2024
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 23:6, s. 7438-7452
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of resource allocation, pricing and application caching for latency sensitive task offloading in serverless edge computing. We model the interaction between a profit-maximizing operator and cost-minimizing Wireless Devices (WDs) as a Stackelberg game where the operator is the leader and decides the price, resource allocation and set of applications to cache, while the WDs are the followers and decide whether to offload their tasks. We first show that the game has a Subgame Perfect Equilibrium (SPE), but computing it, is NP-hard. Importantly, we show that an SPE, which maximizes the operator's revenue, results in minimal energy consumption among the WDs. For computing an approximate SPE, we propose a linear time approximation algorithm with bounded approximation ratio for resource allocation and pricing, and we propose an efficient heuristic based on the utility density of individual applications for the joint optimization of caching, resource allocation and pricing. Our results show that the proposed algorithm outperforms state-of-the-art methods by up to an order of magnitude both in terms of revenue and total energy savings and has small computational overhead. An interesting feature of our results is that the utility of the operator is maximized by a solution that maximizes the WDs' energy savings through computation offloading, which makes it a promising candidate for energy efficient edge cloud deployments.
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| 44. |
- Tutuncuoglu, Feridun, et al.
(författare)
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Optimal Service Caching and Pricing in Edge Computing : a Bayesian Gaussian Process Bandit Approach
- 2022
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; , s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- Motivated by the emergence of function-as-a-service (FaaS) as a programming abstraction for edge computing, we consider the problem of caching and pricing applications for edge computation offloading in a dynamic environment where (WDs) can be active or inactive at any point in time. We model the problem as a single leader multiple-follower Stackelberg game, where the service operator is the leader and decides what applications to cache and how much to charge for their use, while the WDs are the followers and decide whether or not to offload their computations. We show that the WDs' interaction can be modeled as a player-specific congestion game and show the existence and computability of equilibria. We then show that under perfect and complete information the equilibrium price of the service operator can be computed in polynomial time for any cache placement. For the incomplete information case, we propose a Bayesian Gaussian Process Bandit algorithm for learning an optimal price for a cache placement and provide a bound on its asymptotic regret. We then propose a Gaussian process approximation-based greedy heuristic for computing the cache placement. We use extensive simulations to evaluate the proposed learning scheme, and show that it outperforms state of the art algorithms by up to 50% at little computational overhead.
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| 45. |
- van de Beek, Jaap, et al.
(författare)
-
TV white space in Europe
- 2012
-
Ingår i: IEEE Transactions on Mobile Computing. - 1536-1233 .- 1558-0660. ; 11:2, s. 178-188
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study the availability of TV white spaces in Europe. Specifically, we focus on the 470-790 MHz UHF band, which will predominantly remain in use for TV broadcasting after the analog-to-digital switch-over and the assignment of the 800 MHz band to licensed services have been completed. The expected number of unused, available TV channels in any location of the 11 countries we studied is 56 percent when we adopt the statistical channel model of the ITU-R. Similarly, a person residing in these countries can expect to enjoy 49 percent unused TV channels. If, in addition, restrictions apply to the use of adjacent TV channels, these numbers reduce to 25 and 18 percent, respectively. These figures are significantly smaller than those recently reported for the United States. We also study how these results change when we use the Longley-Rice irregular terrain model instead. We show that while the overall expected availability of white spaces is essentially the same, the local variability of the available spectrum shows significant changes. This underlines the importance of using appropriate system models before making far-reaching conclusions.
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| 46. |
- Xu, Chao, et al.
(författare)
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Optimal Status Updates for Minimizing Age of Correlated Information in IoT Networks With Energy Harvesting Sensors
- 2024
-
Ingår i: IEEE Transactions on Mobile Computing. - : IEEE COMPUTER SOC. - 1536-1233 .- 1558-0660. ; 23:6, s. 6848-6864
-
Tidskriftsartikel (refereegranskat)abstract
- Many real-time applications of the Internet of Things (IoT) need to deal with correlated information generated by multiple sensors. The design of efficient status update strategies that minimize the Age of Correlated Information (AoCI) is a key factor. In this paper, we consider an IoT network consisting of sensors equipped with the energy harvesting (EH) capability. We optimize the average AoCI at the data fusion center (DFC) by appropriately managing the energy harvested by sensors, whose true battery states are unobservable during the decision-making process. Particularly, we first formulate the dynamic status update procedure as a partially observable Markov decision process (POMDP), where the environmental dynamics are unknown to the DFC. In order to address the challenges arising from the causality of energy usage, unknown environmental dynamics, unobservability of sensors' true battery states, and large-scale discrete action space, we devise a deep reinforcement learning (DRL)-based dynamic status update algorithm. The algorithm leverages the advantages of the soft actor-critic and long short-term memory techniques. Meanwhile, it incorporates our proposed action decomposition and mapping mechanism. Extensive simulations are conducted to validate the effectiveness of our proposed algorithm by comparing it with available DRL algorithms for POMDPs.
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| 47. |
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| 48. |
- Yuan, Di, et al.
(författare)
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Dual Decomposition for Computational Optimization of Minimum-Power Shared Broadcast Tree in Wireless Networks
- 2012
-
Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 11:12, s. 2008-2019
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of constructing a shared broadcast tree (SBT) in wireless networks, such that the total power required for supporting broadcast initiated by all source nodes is minimal. In the well-studied minimum-energy broadcast (MEB) problem, the optimal tree varies by source. In contrast, SBT is source-independent, thus substantially reducing the overhead for information storage and processing. The SBT problem also differs from the range assignment problem (RAP), because the power for message forwarding in SBT, although being source-independent, depends on from which tree neighbor the message is received. We approach SBT from a computational optimization standpoint, and present a dual decomposition method applied to an optimization model that embeds multiple directed trees into a shared tree. For the dual decomposition method, some of the constraints in the model are preferably formulated implicitly. The dual decomposition scheme is coupled with a fast local search algorithm. We report computational results demonstrating the effectiveness of the proposed approach. In average, the performance gap to global optimality is less than three percent.
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| 49. |
- Yue, Jing, et al.
(författare)
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Coding for Distributed Fog Computing in Internet of Mobile Things
- 2021
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Ingår i: IEEE Transactions on Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1233 .- 1558-0660. ; 20:4, s. 1337-1350
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Tidskriftsartikel (refereegranskat)abstract
- Internet of Mobile Things (IoMTs) refers to the interconnection of mobile devices, for example, mobile phones, vehicles, robots, etc. For mobile data, strong extra processing resources are normally required due to the limited physical resources of the mobile devices in IoMTs. Due to latency or bandwidth limitations, it may be infeasible to transfer a large amounts of mobile data to remote server for processing. Thus, distributed computing is one of the potential solutions to overcome these limitations. We consider the device mobility in IoMTs. Two situations of the movement position of the mobile devices, i.e., unpredictable and predictable, are considered. In addition, three possible relative positions between the two server sets which respectively correspond to the positions of a mobile device for computation tasks offloading and for output results receiving, i.e., within the same server sets, with two different server sets and with two adjacent server sets, are studied. Coded schemes with high flexibility and low complexity are proposed based on Fountain codes to reduce the total processing time and latency of the distributed fog computing process in IoMTs for the above different situations. The latency related performance, i.e., the computation, the communication and the transmission loads, is analyzed. We also compare of the Fountain code-based and the uncoded schemes and numerical results demonstrate that shorter total processing time and lower latency can be achieved by the Fountain code-based schemes.
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| 50. |
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