Publications
246 results found
Benkhelifa F, McCann JA, 2020, Resource allocation for NOMA-based LPWA networks powered by energyharvesting, IEEE Wireless Communications and Networking Conference (WCNC), Publisher: arXiv
In this paper, we explore perpetual, scalable, Low-powered Wide-area networks (LPWA). Specifically we focus on the uplink transmissions of non-orthogonal multiple access (NOMA)-based LPWA networks consisting of multiple self-powered nodes and a NOMA-based single gateway. The self-powered LPWA nodes use the "harvest-then-transmit" protocol where they harvest energy from ambient sources (solar and radio frequency signals), then transmit their signals. The main features of the studied LPWA network are different transmission times-on-air, multiple uplink transmission attempts, and duty cycle restrictions. The aim of this work is to maximize the time-averaged sum of the uplink transmission rates by optimizing the transmission time-on-air allocation, the energy harvesting time allocation and the power allocation; subject to a maximum transmit power and to the availability of the harvested energy. We propose a low complex solution which decouples the optimization problem into three sub-problems: weassign the LPWA node transmission times (using either the fair or unfairapproaches), we optimize the energy harvesting (EH) times using aone-dimensional search method, and optimize the transmit powers using aconcave-convex (CCCP) procedure. In the simulation results, we focus on Long Range (LoRa) networks as a practical example LPWA network. We validate our proposed solution and we observe a $15\%$ performance improvement when using NOMA.
Bhatia L, Breza M, Marfievici R, et al., 2020, Dataset: LoED: The LoRaWAN at the Edge dataset, The 3rd International SenSys+BuildSys Workshop on Data: Acquisition to Analysis, Publisher: ACM, Pages: 7-8
This paper presents the LoRaWAN at the Edge Dataset (LoED), an open LoRaWAN packet dataset collected at gateways. Real-world LoRaWAN datasets are important for repeatable sensor-network and communications research and evaluation as, if carefully collected, they provide realistic working assumptions. LoED data is collected from nine gateways over a four month period in a dense urban environment. The dataset contains packet header information and all physical layer properties reported by gateways such as the CRC, RSSI, SNR and spreading factor. Files are provided to analyse the data and get aggregated statistics. The dataset is available at: doi.org/10.5281/zenodo.4121430
Altherwy YN, McCann JA, 2020, SING: free space SensING of grape moisture using RF shadowing, IEEE Transactions on Instrumentation and Measurement, Vol: 70, Pages: 1-12, ISSN: 0018-9456
Convenient, non-obtrusive, low-cost, and accurate sensing of fruit moisture content is crucial for the scientific studies of Pomology and Viticulture and their associated agriculture. It can provide early indicators of yield estimation and crop health as well as providing data for food production and precision farming systems. With a focus on grapes, we introduce SING, a scheme that senses grape moisture content by utilizing RF signals but without physical contact with the fruit. In this paper, we extend the investigation of the theoretical relationship between the dielectric properties and the moisture content of agricultural products to establish a sensing model in the 5 GHz band. To make the work practical, we are first to measure the dielectric properties of grape bunches (not individually as that would be destructive), presenting a unique measurement challenge as internal grapes are hidden. In doing so, we demonstrate that our technique precisely estimates moisture content to a high degree of accuracy (90Current RF sensing models to estimate moisture are destructive; they require samples to be constrained in containers. Our work is first to dispense with such impracticalities, and, without contact with the object, accurately measures non-uniform grape clusters in open space. We demonstrate that SING is superior to existing work in its ability to accurately measure the dielectric properties of non-uniform fruit objects and test this through both lab-based experimentation and preliminary outdoor vineyard tests.
Webster M, Breza M, Dixon C, et al., 2020, Exploring the effects of environmental conditions and design choices on IoT systems using formal methods, Journal of Computational Science, Vol: 45, ISSN: 1877-7503
Wireless communication protocols are often used in critical applications, e.g., urban water supply networks or healthcare monitoring within the Internet of Things. It is essential that control software and protocols for such systems are verified to be both robust and reliable. The effects on the hardware caused by environmental conditions and the choice of parameters used by the protocol are among the largest obstacles to robustness and reliability in wireless systems. In this paper we use formal verification to verify that a wireless sensor network synchronization and dissemination protocol is not adversely affected by these factors.
Wang H, Zhou G, Bhatia L, et al., 2020, Energy-neutral and QoS-aware protocol in wireless sensor networks for health monitoring of hoisting systems, IEEE Transactions on Industrial Informatics, Vol: 16, Pages: 5543-5553, ISSN: 1551-3203
Hoisting equipment is core to many industrial systems and therefore their state of health significantly affects production lines and personnel safety; this is especially important in environments such as coal mines. The health of the hoisting system, can be estimated by deploying energy harvesting wireless sensor nodes that monitor the drum surface stress. In this network of sensor devices, it is very costly to send highly sampled data as it causes radio congestion and consumes energy. However, from our experience of sensing hoist systems, we note that the data observed at the upper surface of the hoist is significantly more indicative of the state of health of the whole system, compared with data sensed at the lower surface. Therefore, we need to take advantage of this to optimise the communications of sensor nodes. However, scarce energy can be collected for these devices from the hoist itself, along with the prioritised Quality of Service (QoS) requirements (throughput, delay) of monitoring signals, raises important challenges for energy management. In this paper, we use Lyapunov optimisation techniques and propose an Energy-neutral and QoS-aware Protocol (EQP), including duty cycling and network scheduling to solve it. Extensive simulations show that EQP helps sensor nodes realize consecutive monitoring, and achieve more than 38% utility gain compared with existing strategies.
Wei Z, Pagani A, Fu G, et al., 2020, Optimal sampling of water distribution network dynamics using graph fourier transform, IEEE Transactions on Network Science and Engineering, Vol: 7, Pages: 1570-1582, ISSN: 2327-4697
Water distribution networks are critical infrastructures under threat from the accidental or intentional release of contaminants. Large-scale data collection is vital for digital twin modelling, but remains challenging in underground spaces over vast areas. Therefore, inferring the contaminant spread process with minimal sensor data is important. Existing sensor deployment optimisation approaches use scenario-based numerical optimisation, but suffer from scalability issues and lack performance guarantees. Analytical graph theoretic approaches link complex network topology (e.g. Laplacian spectra) to optimal sensing locations, but neglect the complex fluid dynamics. Alternative data-driven approaches such as compressed sensing offer limited sample node reduction. In this work, we introduce a novel data-driven Graph Fourier Transform that exploits the low-rank property of networked dynamics to optimally sample WDNs. The proposed GFT guarantees error free recovery of network dynamics and offers attractive compression and scaling improvements over existing numerical optimisation, compressed sensing, and graph theoretic approaches. By testing on 100 different contaminant propagation data sets, the proposed scheme shows that, on average, with nearly 30% of the junctions monitored, we are able to fully recover the networked dynamics. The framework is useful for other monitoring applications of WDNs and can be applied to a variety of infrastructure sensing for digital twin modelling.
Wu D, Lambrinos L, Przepiorka T, et al., 2020, Enabling Efficient Offline Mobile Access to Online Social Media on Urban Underground Metro Systems, IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS, Vol: 21, Pages: 2750-2764, ISSN: 1524-9050
Wu D, Nie X, Asmare E, et al., 2020, Towards distributed SDN: mobility management and flow scheduling in software defined urban IoT, IEEE Transactions on Parallel and Distributed Systems, Vol: 31, Pages: 1400-1418, ISSN: 1045-9219
IEEE The growth of Internet of Things (IoT) devices with multiple radio interfaces has resulted in a number of urban-scale deployments of IoT multinetworks, where heterogeneous wireless communication solutions coexist. Managing the multinetworks for seamless IoT access and handover, especially in mobile environments, is a key challenge. Software-defined networking (SDN) is emerging as a promising paradigm for quick and easy configuration of network devices, but its application in urban-scale multinetworks requiring heterogeneous and frequent IoT access is not well studied. We present UbiFlow that adopts multiple controllers to divide urban-scale SDN into different geographic partitions and achieve distributed control of IoT flows. A distributed hashing based overlay structure is proposed to maintain network scalability and consistency. Based on this UbiFlow overlay structure, the relevant issues pertaining to mobility management such as scalable control, fault tolerance, and load balancing have been carefully studied. The UbiFlow controller differentiates flow scheduling based on per-device requirements and whole-partition capabilities. Therefore, it can present a network status view and optimized selection of access points in multinetworks to satisfy IoT flow requests, while guaranteeing network performance for each partition. Our experiments confirm that UbiFlow can successfully achieve scalable mobility management and robust flow scheduling in IoT multinetworks; e.g. 67.21% throughput improvement, 72.99% reduced delay, and 69.59% jitter improvements, compared with alternative SDN systems.
Spina A, Breza M, Dulay N, et al., 2020, XPC: fast and reliable synchronous transmission protocols for 2-phase commit and 3-phase commit, The 2020 International Conference on Embedded Wireless Systems and Networks, Publisher: ACM, Pages: 73-84
The improvement of software abstractions and frame-works for programmers is one of the major challenges forthe engineering of reliable and efficient wireless sensing sys-tems. We address this challenge with X Process Commit(XPC), an atomic commit protocol framework, andHybrid,a Synchronous Transmission (ST) communication approach.Hybridexploits the reliability of Glossy and the speed ofChaos, two Synchronous Transmission primitives, to getlower latency and higher reliability than either on their own.Hybridis a general approach that can provide reliable com-munication for any round based protocol. We use XPC andHybridto build the classical 2-phase and 3-phase commitprotocols. Through extensive experimentation, we comparethe performance of the 2-phase and 3-phase commit proto-cols when they useHybrid, Glossy, and Chaos for commu-nication. Our results show thatHybridis more robust thanChaos to radio interference, with almost 100% reliability in anetwork of nodes suffering from moderate radio interference,13% to 50% faster than Glossy, and has comparable over-heads to other state of the art ST atomic commit approachesA2/Synchrotron.
Wang H, Zhou G, Xue R, et al., 2020, A driving-behavior-based SoC prediction method for light urban vehicles powered by supercapacitors, IEEE Transactions on Intelligent Transportation Systems, Vol: 21, Pages: 2090-2099, ISSN: 1524-9050
Range anxiety is one of the problems that hinder the large-scale application of electric vehicles (EVs). We propose a driving-behavior-based State-of-Charge (SoC) prediction (DBSP) algorithm to overcome this problem. This algorithm can determine whether drivers can reach their destinations while also predicting the SoC if drivers were to return the trip. First, two supercapacitor equivalent circuit models are established with one based on the historical average power and the other based on the equivalent current, which is proposed in this algorithm. Then, based on the equivalent transformation of the two models, an analytical expression relating the historical average power and the predicted SoC is derived by using the equivalent current as a “bridge.” Therefore, the predicted SoC can be dynamically adjusted in response to recorded historical data, including the output power, speed, and distance of EVs powered by supercapacitors. The simulation results demonstrate that the total prediction error is less than 0.5% of the real SoC at different initial SoC and temperature, which represents idealized behavior-based driving. In contrast, in actual driving experiments, the total prediction error is less than 3% of the real SoC at different initial SoC and temperature.
Tomic I, Breza M, McCann J, 2020, Jamming-resilient control and communication framework for cyber physical systems, Living in the Internet of Things 2019, Publisher: IET
The control and monitoring of large infrastructure installations is becoming smarter, cheaper to run and easier to managethrough the use of wireless sensor and actuator networks (WSANs). Cyber Physical Systems (CPSs)are the combination of cyber sensing via WSANs and physical control. The problem withthe use of WSANs in CPSs is that they make the whole system being controlled exposed to the world andvulnerable to theft or cyber-attacks.In this article we examine the failure of CPS infrastructure due to intelligent radio jamming.The intelligent jammer employs a protocol-aware jamming strategy to learn the transmission period of a sensor device.It then broadcasts noise to disrupt the wireless communication and destabilise the CPS.Wepresent a CPS control and communication approachto counter thethreat of intelligentradio jamming. The approach exploitsthe properties of the event-based controlstrategy combined with a reservation-based communication protocolthat employs obfuscation. We usea physical model of a water distribution networkto demonstrate that the approachis resilient to an intelligent jamming attack, it is able to continue normaloperationof the systemand maintain the desired level of performance while achieving low overheads.
Li K, Benkhelifa F, McCann J, 2020, Resource allocation for non-orthogonal multiple access (NOMA) enabled LPWA networks, IEEE GLOBECOM 2019, Publisher: IEEE, Pages: 1-6
In this paper, we investigate the resource allocation for uplink non-orthogonal multiple access (NOMA) enabled low-power wide-area (LPWA) networks to support the massive connectivity of users/nodes. Here, LPWA nodes communicate with a central gateway through resource blocks like channels, transmission times, bandwidths, etc. The nodes sharing the same resource blocks suffer from intra-cluster interference and possibly inter-cluster interference, which makes current LPWA networks unable to support the massive connectivity. Using the minimum transmission rate metric to highlight the interference reduction that results from the addition of NOMA, and while assuring user throughput fairness, we decompose the minimum rate maximization optimization problem into three sub- problems. First, a low-complexity sub-optimal nodes clustering scheme is proposed assigning nodes to channels based on their normalized channel gains. Then, two types of transmission time allocation algorithms are proposed that either assure fair or unfair transmission time allocation between LPWA nodes sharing the same channel. For a given channel and transmission time allocation, we further propose an optimal power allocation scheme. Simulation evaluations demonstrate approximately 100dB improvement of the selected metric for a single network with 4000 active nodes.
Benkhelifa F, ElSawy H, McCann JA, et al., 2020, Recycling cellular energy for self-sustainable IoT networks: a spatiotemporal study, IEEE Transactions on Wireless Communications, Vol: 19, Pages: 2699-2712, ISSN: 1536-1276
This paper investigates the self-sustainability of an overlay Internet of Things (IoT) network that relies on harvesting energy from a downlink cellular network. Using stochastic geometry and queueing theory, we develop a spatiotemporal model to derive the steady state distribution of the number of packets in the buffers and energy levels in the batteries of IoT devices given that the IoT and cellular communications are allocated disjoint spectrum. Particularly, each IoT device is modelled via a two-dimensional discrete-time Markov Chain (DTMC) that jointly tracks the evolution of the data buffers and energy battery. In this context, stochastic geometry is used to derive the energy generation at the batteries and the packet transmission success probability from buffers taking into account the mutual interference from other active IoT devices. To this end, we show the Pareto-Frontiers of the sustainability region, which define the network parameters that ensure stable network operation and finite packet delay. Furthermore, the spatially averaged network performance, in terms of transmission success probability, average queueing delay, and average queue size are investigated. For self-sustainable networks, the results quantify the required buffer size and packet delay, which are crucial for the design of IoT devices and time critical IoT applications.
Yu W, McCann J, Zhang C, 2019, Efficient pairwise penetrating-rank similarity retrieval, ACM Transactions on the Web, Vol: 13, Pages: 1-52, ISSN: 1559-1131
Many web applications demand a measure of similarity between two entities, such as collaborative filtering, web document ranking, linkage prediction, and anomaly detection. P-Rank (Penetrating-Rank) has been accepted as a promising graph-based similarity measure, as it provides a comprehensive way of encoding both incoming and outgoing links into assessment. However, the existing method to compute P-Rank is iterative in nature and rather cost-inhibitive. Moreover, the accuracy estimate and stability issues for P-Rank computation have not been addressed. In this article, we consider the optimization techniques for P-Rank search that encompasses its accuracy, stability, and computational efficiency. (1) The accuracy estimation is provided for P-Rank iterations, with the aim to find out the number of iterations, k, required to guarantee a desired accuracy. (2) A rigorous bound on the condition number of P-Rank is obtained for stability analysis. Based on this bound, it can be shown that P-Rank is stable and well-conditioned when the damping factors are chosen to be suitably small. (3) Two matrix-based algorithms, applicable to digraphs and undirected graphs, are, respectively, devised for efficient P-Rank computation, which improves the computational time from O(kn3) to O(υ n2+υ6) for digraphs, and to O(υn2) for undirected graphs, where n is the number of vertices in the graph, and υ (≪ n) is the target rank of the graph. Moreover, our proposed algorithms can significantly reduce the memory space of P-Rank computations from O(n2) to O(υn+υ4) for digraphs, and to O(υ n) for undirected graphs, respectively. Finally, extensive experiments on real-world and synthetic datasets demonstrate the usefulness and efficiency of the proposed techniques for P-Rank similarity assessment on various networks.
Mcgrane SJ, Acuto M, Artioli F, et al., 2019, Scaling the nexus: Towards integrated frameworks for analysing water, energy and food, Geographical Journal, Vol: 185, Pages: 419-431, ISSN: 0016-7398
The emergence of the water-energy-food (WEF) nexus has resulted in changes to the way we perceive our natural resources. Stressors such as climate change and population growth have highlighted the fragility of our WEF systems, necessitating integrated solutions across multiple scales. While a number of frameworks and analytical tools have been developed since 2011, a comprehensive WEF nexus tool remains elusive, hindered in part by our limited data and understanding of the interdependencies and connections across the WEF systems. To achieve this, the community of academics, practitioners and policy-makers invested in WEF nexus research are addressing several critical areas that currently remain as barriers. First, the plurality of scales (e.g., spatial, temporal, institutional, jurisdictional) necessitates a more comprehensive effort to assess interdependencies between water, energy and food, from household to institutional and national levels. Second, and closely related to scale, a lack of available data often hinders our ability to quantify physical stocks and flows of resources. Overcoming these barriers necessitates engaging multiple stakeholders, and using experiences and local insights to better understand nexus dynamics in particular locations or scenarios, and we exemplify this with the inclusion of a UK-based case study on exploring the nexus in a particular geographical area. We elucidate many challenges that have arisen across nexus research, including the impact of multiple scales in operation, and concomitantly, what impact these scales have on data accessibility. We assess some of the critical frameworks and tools that are applied by nexus researchers and articulate some of the steps required to develop from nexus thinking to an operationalisable concept, with a consistent focus on scale and data availability.
Fu A, Tomic I, McCann J, 2019, Asynchronous sampling for decentralized periodic event-triggered control, 2019 American Control Conference, Publisher: IEEE, Pages: 145-150, ISSN: 2378-5861
Decentralized periodic event-triggered control(DPETC) strategies are an attractive solution for wireless cyber-physical systems where resources such as network bandwidthand sensor power are scarce. This is because these strategieshave the advantage of preventing unnecessary data transmis-sions and therefore reduce bandwidth and energy requirements,however the sensor sampling regime remains synchronous.Typically the action of sampling leads almost immediately toa transmission on an event being detected. If the sampling issynchronous, multiple transmission requests may be raised atthe same time which further leads to bursty traffic patterns.Bursty traffic patterns are critical to the DPETC systemsperformance as the probability of collisions and the amount ofrequested bandwidth resources become high ultimately causingdelays. In this paper, we propose an asynchronous samplingscheme for DPETC. The scheme ensures that at each samplingtime, no more than one transmission request can be generatedwhich prevents the occurrence of network traffic collision.At the same time, for the DPETC system with asynchronoussampling a pre-designed global exponential stability andL2-gain performance can still be guaranteed. We illustrate theeffectiveness of the approach through a numerical example.
Qin Z, Liu Y, Li GY, et al., 2019, Performance analysis of clustered LoRa networks, IEEE Transactions on Vehicular Technology, Vol: 68, Pages: 7616-7629, ISSN: 0018-9545
In this paper, we investigate the uplink transmission performance of low-power wide-area (LPWA) networks with regards to coexisting radio modules. We adopt the long-range (LoRa) radio technique as an example of the network of focus, even though our analysis can be easily extended to other situations. We exploit a new topology to model the network, where the node locations of LoRa follow a Poisson cluster process while other coexisting radio modules follow a Poisson point process. Unlike most of the performance analysis based on stochastic geometry, we take noise into consideration. More specifically, two models, with a fixed and a random number of active LoRa nodes in each cluster, respectively, are considered. To obtain insights, both the exact and simple approximated expressions for coverage probability are derived. Based on them, area spectral efficiency and energy efficiency are obtained. From our analysis, we show how the performance of LPWA networks can be enhanced by adjusting the density of LoRa nodes around each LoRa receiver. Moreover, the simulation results unveil that the optimal number of active LoRa nodes in each cluster exists to maximize the area spectral efficiency.
Benkhelifa F, Qin Z, McCann J, 2019, Minimum throughput maximization in LoRa networks powered by ambient energy harvesting, ICC 2019 - 2019 IEEE International Conference on Communications (ICC), Publisher: Institute of Electrical and Electronics Engineers, ISSN: 1550-3607
In this paper, we investigate the uplink transmissions in low-power wide-area networks (LPWAN) where the users are self-powered by the energy harvested from the ambient environment. Demonstrating their potential in supporting diverse Internet-of-Things (IoT) applications, we focus on long range (LoRa) networks where the LoRa users are using the harvested energy to transmit data to a gateway via different spreading codes. Precisely, we study the throughput fairness optimization problem for LoRa users by jointly optimizing the spreading factor (SF) assignment, energy harvesting (EH) time duration, and the transmit power of LoRa users. First, through examination of the various permutations of collisions among users, we derive a general expression of the packet collision time between LoRa users, which depends on the SFs and EH duration requirements. Then, after reviewing prior SF allocation work, we develop two types of algorithms that either assure fair SF assignment indeed purposefully `unfair' allocation schemes for the LoRa users. Our results unearth three new findings. Firstly, we demonstrate that, to maximize the minimum rate, the unfair SF allocation algorithm outperforms the other approaches. Secondly, considering the derived expression of packet collision between simultaneous users, we are now able to improve the performance of the minimum rate of LoRa users and show that it is protected from inter-SF interference which occurs between users with different SFs. That is, imperfect SF orthogonality has no impact on minimum rate performance. Finally, we have observed that co-SF interference is the main limitation in the throughput performance, and not the energy scarcity.
Tomic I, Breza MJ, Jackson G, et al., 2019, Design and evaluation of jamming resilient cyber-physical systems, IEEE International Conference on Cyber, Physical and Social Computing (CPSCom 2018), Publisher: IEEE
There is a growing movement to retrofit ageing,large scale infrastructures, such as water networks, with wirelesssensors and actuators. Next generation Cyber-Physical Systems(CPSs) are a tight integration of sensing, control, communication,computation and physical processes. The failure of any one ofthese components can cause a failure of the entire CPS. Thisrepresents a system design challenge to address these interde-pendencies. Wireless communication is unreliable and prone tocyber-attacks. An attack upon the wireless communication of CPSwould prevent the communication of up-to-date information fromthe physical process to the controller. A controller without up-to-date information is unable to meet system’s stability and perfor-mance guarantees. We focus on design approach to make CPSssecure and we evaluate their resilience to jamming attacks aimedat disrupting the system’s wireless communication. We considerclassic time-triggered control scheme and various resource-aware event-triggered control schemes. We evaluate these ona water network test-bed against three jamming strategies:constant, random, and protocol aware. Our test-bed results showthat all schemes are very susceptible to constant and randomjamming. We find that time-triggered control schemes are justas susceptible to protocol aware jamming, where some event-triggered control schemes are completely resilient to protocolaware jamming. Finally, we further enhance the resilience ofan event-triggered control scheme through the addition of adynamical estimator that estimates lost or corrupted data.
Yu W, Lin X, Zhang W, et al., 2019, SimRank*: effective and scalable pairwise similarity search based on graph topology, VLDB Journal, Vol: 28, Pages: 401-426, ISSN: 1066-8888
Given a graph, how can we quantify similarity between two nodes in an effective and scalable way? SimRank is an attractive measure of pairwise similarity based on graph topologies. Its underpinning philosophy that “two nodes are similar if they are pointed to (have incoming edges) from similar nodes” can be regarded as an aggregation of similarities based on incoming paths. Despite its popularity in various applications (e.g., web search and social networks), SimRank has an undesirable trait, i.e., “zero-similarity”: it accommodates only the paths of equal length from a common “center” node, whereas a large portion of other paths are fully ignored. In this paper, we propose an effective and scalable similarity model, SimRank*, to remedy this problem. (1) We first provide a sufficient and necessary condition of the “zero-similarity” problem that exists in Jeh and Widom’s SimRank model, Li et al. ’s SimRank model, Random Walk with Restart (RWR), and ASCOS++. (2) We next present our treatment, SimRank*, which can resolve this issue while inheriting the merit of the simple SimRank philosophy. (3) We reduce the series form of SimRank* to a closed form, which looks simpler than SimRank but which enriches semantics without suffering from increased computational overhead. This leads to an iterative form of SimRank*, which requires O(Knm) time and O(n2) memory for computing all (n2) pairs of similarities on a graph of n nodes and m edges for K iterations. (4) To improve the computational time of SimRank* further, we leverage a novel clustering strategy via edge concentration. Due to its NP-hardness, we devise an efficient heuristic to speed up all-pairs SimRank* computation to O(Knm~) time, where m~ is generally much smaller than m. (5) To scale SimRank* on billion-edge graphs, we propose two memory-efficient single-source algorithms, i.e., ss-gSR* for geometric SimRank*, and ss-eSR* for exp
Liu X, Qin Z, Gao Y, et al., 2019, Resource allocation in wireless powered IoT networks, IEEE Internet of Things Journal, Vol: 6, Pages: 4935-4945, ISSN: 2327-4662
In this paper, the efficient resource allocation for the uplink transmission of wireless powered Internet of Things (IoT) networks is investigated. We adopt LoRa technology as an example in the IoT network, but this paper is still suitable for other communication technologies. Allocating limited resources, like spectrum and energy resources, among a massive number of users faces critical challenges. We consider grouping wireless powered IoT users into available channels first and then investigate power allocation for users grouped in the same channel to improve the network throughput. Specifically, the user grouping problem is formulated as a many to one matching game. It is achieved by considering IoT users and channels as selfish players which belong to two disjoint sets. Both selfish players focus on maximizing their own utilities. Then we propose an efficient channel allocation algorithm (ECAA) with low complexity for user grouping. Additionally, a Markov decision process is used to model unpredictable energy arrival and channel conditions uncertainty at each user, and a power allocation algorithm is proposed to maximize the accumulative network throughput over a finite-horizon of time slots. By doing so, we can distribute the channel access and dynamic power allocation local to IoT users. Numerical results demonstrate that our proposed ECAA algorithm achieves near-optimal performance and is superior to random channel assignment, but has much lower computational complexity. Moreover, simulations show that the distributed power allocation policy for each user is obtained with better performance than a centralized offline scheme.
Puliafito A, Gangopadhyay A, Ganti R, et al., 2019, Message from the SMARTCOMP 2019 conference chairs
Qin Z, Li FY, Li GY, et al., 2019, Low-power wide-area networks for sustainable IoT, IEEE Wireless Communications, Vol: 26, Pages: 140-145, ISSN: 1536-1284
LPWA networks are attracting extensive attention because of their ability to offer low-cost and massive connectivity to IoT devices distributed over wide geographical areas. This article provides a brief overview of the existing LPWA technologies and useful insights to aid the large-scale deployment of LPWA networks. In particular, we first review the currently competing candidates of LPWA networks, such as NB-IoT and LoRa, in terms of technical fundamentals and large-scale deployment potential. Then we present two implementation examples of LPWA networks. By analyzing the field-test results, we identify several challenges that prevent LPWA technologies from moving from theory to wide-spread practice.
McCann JA, Picco GP, Gluhak A, et al., 2019, Connected things connecting Europe, Communications of the ACM, Vol: 62, Pages: 46-51, ISSN: 0001-0782
Benkhelifa F, ElSawy H, McCann J, et al., 2019, Recycling cellular downlink energy for overlay self-sustainable IoT networks, 2018 IEEE Global Communications Conference: Wireless Communications, Publisher: IEEE
This paper investigates the self-sustainability of anoverlay Internet of Things (IoT) network that relies on harvest-ing energy from a downlink cellular network. Using stochasticgeometry and queueing theory, we develop a spatiotemporalmodel to derive the steady state distribution of the numberof packets in the buffers and energy levels in the batteries ofIoT devices given that the IoT and cellular communicationsare allocated disjoint spectrum. Particularly, each IoT deviceis modeled via a two-dimensional discrete-time Markov Chain(DTMC) that jointly tracks the evolution of data buffer andenergy battery. In this context, stochastic geometry is used toderive the energy generation at the batteries and the packettransmission probability from buffers taking into account themutual interference from other active IoT devices. To this end,we show the Pareto-Frontiers of the sustainability region, whichdefines the network parameters that ensure stable networkoperation and finite packet delay. The results provide severalinsights to design self-sustainable IoT networks.Index Terms—Spatiotemporal models, stochastic geometry,queuing theory, energy harvesting, packet transmission successprobability, two-dimensional discrete-time Markov chain, sta-bility conditions.
McCann J, Zheng Q, 2019, Message from the Program Chairs: ICPADS 2018, Proceedings of the International Conference on Parallel and Distributed Systems, Pages: xxii-xxiii, ISSN: 1521-9097
Webster M, Breza M, Dixon C, et al., 2019, Formal verification of synchronisation, gossip and environmental effects for wireless sensor networks, Electronic Communications of the EASST, Vol: 76, ISSN: 1863-2122
The Internet of Things (IoT) promises a revolution in the monitoring and control of a wide range of applications, from urban water supply networks and precision agriculture food production, to vehicle connectivity and healthcare monitoring. For applications in such critical areas, control software and protocols for IoT systems must be verified to be both robust and reliable. Two of the largest obstacles to robustness and reliability in IoT systems are effects on the hardware caused by environmental conditions, and the choice of parameters used by the protocol. In this paper we use probabilistic model checking to verify that a synchronisation and dissemination protocol for Wireless Sensor Networks (WSNs) is correct with respect to its requirements, and is not adversely affected by the environment. We show how the protocol can be converted into a logical model and then analysed using the probabilistic model-checker, PRISM. Using this approach we prove under which circumstances the protocol is guaranteed to synchronise all nodes and disseminate new information to all nodes. We also examine the bounds on synchronisation as the environment changes the performance of the hardware clock, and investigate the scalability constraints of this approach.
Altherwy YN, Elmallah ES, McCann JA, 2019, Poster Abstract: Two-Terminal Connectivity in UWSN Probabilistic Graphs: A Polynomial Time Algorithm, 17th ACM Conference on Embedded Networked Sensor Systems (SenSys), Publisher: ASSOC COMPUTING MACHINERY, Pages: 444-445
Jiang S, Cao J, McCannt JA, et al., 2019, Privacy-preserving and Efficient Multi-keyword Search Over Encrypted Data on Blockchain, 2nd IEEE International Conference on Blockchain (Blockchain), Publisher: IEEE COMPUTER SOC, Pages: 405-410
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Sevegnani M, Kabac M, Calder M, et al., 2018, Modelling and verification of large-scale sensor network infrastructures, 23rd International Conference on Engineering of Complex Computer Systems (ICECCS), Publisher: IEEE, Pages: 71-81
Large-scale wireless sensor networks (WSN) are increasingly deployed and an open question is how they can support multiple applications. Networks and sensing devices are typically heterogeneous and evolving: topologies change, nodes drop in and out of the network, and devices are reconfigured. The key question we address is how to verify that application requirements are met, individually and collectively, and can continue to be met, in the context of large-scale, evolving network and device configurations. We define a modelling and verification framework based on Bigraphical Reactive Systems (BRS) for modelling, with bigraph patterns and temporal logic properties for specifying application requirements. The bigraph diagrammatic notation provides an intuitive representation of concepts such as hierarchies, communication, events and spatial relationships, which are fundamental to WSNs. We demonstrate modelling and verification through a real-life urban environmental monitoring case-study. A novel contribution is automated online verification using BigraphER and replay of real-life sensed data streams and network events by the Cooja network simulator. Performance results for verification of two application properties running on a WSN with up to 200 nodes indicate our framework is capable of handling WSNs of that scale.
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