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Cellular phone networks are often paralyzed after a disaster, as damage to fixed infrastructure, loss of power, and increased demand degrade coverage and quality of service. To ensure disaster victims and first responders have access to reliable local and global communication, we propose EmergeNet, a portable, rapidly deployable, small-scale cellular network. In this article, we describe EmergeNet, which addresses the challenges of emergency and disaster areas. EmergeNet provides free voice calling and text messaging within a disaster area, and enables users of unmodified GSM handsets to communicate with the outside world using the Skype VoIP network. We evaluate EmergeNet?s ability to provide robust service despite high load, limited bandwidth, and software or hardware failures. EmergeNet is uniquely well suited to providing reliable, fairly allocated voice and text communication in emergency and disaster scenarios. [ABSTRACT FROM PUBLISHER]

4G Long Term Evolution is the cellular technology expected to outperform previous generations and to some extent revolutionize the experience of users by taking advantage of the most advanced radio access techniques. However, the strong dependencies between user equipment, base stations, and the Evolved Packet Core limit the flexibility, manageability, and resilience of such networks. If the communication links between UE-eNB or eNB-EPC are disrupted, mobile terminals are unable to communicate. In this article, we reshape the 4G mobile network to move toward more virtual and distributed architectures to improve disaster resilience and drastically reduce the dependency between UE, eNBs, and EPC. First, we present the flexible management entity, a distributed entity that leverages on virtualized EPC functionalities in 4G cellular systems. Second, we introduce a novel device-to-device communication scheme allowing the UE in physical proximity to communicate directly without resorting to coordination with an eNB or EPC entity. [ABSTRACT FROM PUBLISHER]

The rapid increase in network traffic with new bandwidth-hungry applications such as cloud computing and telemedicine makes disaster survivability a crucial concern as the data (and revenue) loss caused by large-scale correlated cascading failures can be very high. To alleviate their impact, new measures should be taken since the nature of the network changes dramatically as available resources decrease during disasters. We develop a metric, called degraded-service tolerance, which can reduce protection cost and network disruption, and support maximal carried traffic in case of disasters. Degraded-service-tolerant connections can be admitted and recovered with reduced bandwidth under resource crunch. Our scheme re-assigns resources among connections by leveraging their degraded-service tolerance. A case study shows how our proposal can be applied to boost network performance during the resource crunch following a disaster. [ABSTRACT FROM PUBLISHER]

Wireless sensor networks (WSNs) have been widely recognized as a promising solution for enhancing various aspects of electric power grid and realizing the vision of smart grid. However, the challenging wireless environment in smart grid creates a number of challenges for WSNs, as a result of which energy efficiency and reliability become critically important. On the other hand, cognitive radio (CR) technology is expected to play a vital role in smart grid networks. The CR equipped sensor networks [or cognitive sensor networks (CSNs)] can effectively address the unique challenges of WSNs in smart grid. In this paper, we aim to design an energy efficient and reliable medium access control (MAC) protocol for CSNs. In this regard, we propose CRB-MAC which is a receiver-based MAC protocol for CSNs. The CRB-MAC uses preamble sampling and opportunistic forwarding techniques for providing high energy efficiency and reliability. In addition, CRB-MAC explicitly accounts for the peculiarities of a CR environment. Analytical and simulation results demonstrate the effectiveness of CRB-MAC as a viable solution for CSNs. [ABSTRACT FROM PUBLISHER]

Wireless sensor networks are built from nodes which have at least one sensor attached to them. To increase robustness and capacity, a signal from one node can be routed through many different nodes before it reaches its destination node (i.e. a base station). A smart antenna with a steerable beam has the potential, compared to a monopole, to increase the signal‐to‐noise ratio between nodes and hence provide more reliable communication paths. In this study, the data routing and link performance of a rhombus‐shaped mesh network using four IEEE 802.15.4 compliant MICAz sensor nodes (motes) is assessed using both monopole and smart antennas. Both reflectionless and multipath‐rich environments are used. It is shown that the electronically steerable parasitic array smart antenna offers a superior performance to a monopole antenna in both environments, while still consuming a similar amount of input power. [ABSTRACT FROM AUTHOR]

Co‐operative communication has been shown to significantly improve energy efficiency in wireless sensor networks. The outdated channel state information (CSI) problem will result in severe performance degradation of co‐operative communication systems including energy efficiency. In this study, the authors analyse the impact of outdated CSI on energy efficiency of amplify‐and‐forward co‐operative hybrid automatic repeat reQuest system. The authors derive the expression of the average energy consumption per bit of data transmission under outdated CSI. Numerical results show the deteriorating effects of outdated CSI on the performance of energy efficiency and transmission reliability in co‐operative communication system. It is also shown that energy efficiency can be improved by error correcting codes mechanism when end‐to‐end signal‐to‐noise ratio at the destination node is within a certain range. [ABSTRACT FROM AUTHOR]

Low‐power medium access control (MAC) protocols used for communication of energy constraint wireless embedded devices do not cope well with situations where transmission channels are highly erroneous. Existing MAC protocols discard corrupted messages which lead to costly retransmissions. To improve transmission performance, it is possible to include an error correction scheme and transmit/receive diversity. It is possible to add redundant information to transmitted packets in order to recover data from corrupted packets. It is also possible to make use of transmit/receive diversity via multiple antennas to improve error resiliency of transmissions. Both schemes may be used in conjunction to further improve the performance. In this study, the authors show how an error correction scheme and transmit/receive diversity can be integrated in low‐power MAC protocols. Furthermore, the authors investigate the achievable performance gains of both methods. This is important as both methods have associated costs (processing requirements; additional antennas and power) and for a given communication situation it must be decided which methods should be employed. The authors' results show that, in many practical situations, error control coding outperforms transmission diversity; however, if very high reliability is required, it is useful to employ both schemes together. [ABSTRACT FROM AUTHOR]

In the recent past, research in the next generation wireless heterogeneous broadband networks has favoured the design of multi‐radio interface over the single radio interface architectures to support desirable features such as a self‐organisation, self‐configuration, reliability and robustness of network operations in a resource‐constrained environment. However, such autonomous network behaviours have been seen to cause an inefficient consumption of energy and frequency channel resources, impacting negatively on the economy and environment. To address the inefficient energy and frequency channel utilisation problems, this study proposes a biological behaviour‐based network resource management method. The research is inspired by such a well‐established optimal foraging theory whereby a solitary biological forager in a random ecosystem makes optimal decisions that maximise its own nutrients consumption, survival probability and lifetime, whereas minimising possible risks associated with its own behaviour. This study has applied this natural principle and developed a Bio‐inspired Energy and Channel (BEACH) management method. The BEACH method is aimed at achieving both efficient communication energy and frequency channel utilisation in the considered distributed wireless multi‐radio network. The efficacy of the developed BEACH method has been extensively validated through computer simulations and shown to yield improved energy‐efficiency and throughput performance. [ABSTRACT FROM AUTHOR]

This study presents the architectural design, software implementation, the validation and flight trial results of an aeronautical communications system developed within the Seamless Aeronautical Networking through integration of Data links Radios and Antennas (SANDRA) project funded by the European 7th Framework Aeronautics and Transport Programme. Based on software defined radio (SDR) techniques, an integrated modular radio (IMR) platform was developed to accommodate several radio technologies. This can drastically reduce the size, weight and cost in avionics with respect to current radio systems implemented as standalone equipment. In addition, the modular approach ensures the possibility to dynamically reconfigure each radio element to operate on a specific type of radio link. A radio resource management (RRM) framework is developed in the IMR consisting of a communication manager for the resource allocation and management of the different radio links and a radio adaptation manager to ensure protocol convergence through IP. The IMR has been validated although flight trials held at Oberpfaffenhofen, Germany in June 2013. The results presented in the paper validate the flexibility and scalability of the IMR platform and demonstrate seamless service coverage across different airspace domains through interworking between the IMR and other components of the SANDRA network. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) bring significant advantages over traditional communications in today's applications, such as environmental monitoring, homeland security, and health care. However, harsh and complex environments pose great challenges in the reliability of WSN communications. To achieve reliable wireless communications within WSNs, it is essential to have a reliable routing protocol and to have a means to evaluate the reliability performance of different routing protocols. In this paper, we first model the reliability of two different types of sensor nodes: 1) energy harvesting sensor nodes and 2) battery-powered sensor nodes. We then present wireless link reliability models for each type of sensor nodes, where effects of different parameters, such as battery life-time, shadowing, noise, and location uncertainty, are considered for analyzing the wireless link reliability. Based on the sensor node and wireless link reliability models, we compare the performance of different routing algorithms in terms of end-to-end path reliability and number of hops. A dynamic routing approach is then proposed to achieve the most reliable end-to-end path in WSNs. Furthermore, to facilitate a fair and comprehensive comparison among different routing algorithms, a cost function approach that integrates the end-to-end path reliability and number of hops is proposed, providing an indicator of quality of service of applications running on WSNs. [ABSTRACT FROM PUBLISHER]

Wireless sensing technology is becoming a new scientific instrument for environmental monitoring under extreme conditions. This class of applications requires reliable, energy-efficient, and self-organizing approaches. Connected dominating sets (CDSs) have been widely used for virtual backbone construction in unstructured wireless sensor networks to control topology, facilitate routing, and extend network lifetime. This paper proposes two distributed algorithms for CDS construction and maintenance in extreme wireless sensor networks. The proposed approaches efficiently construct and maintain a small CDS for challenging environments. Simulation shows that our proposed approaches provide significant energy efficiency without introducing any performance degradation in terms of CDS size. [ABSTRACT FROM PUBLISHER]

Technologies that will lead to adaptive, intelligent, and aware wireless communications systems are expected to offer solutions to the capacity, interference, and reliability problems of wireless networks. The spectrum sensing feature of CR systems is a step forward to better recognize the problems and to achieve efficient spectrum allocation. On the other hand, even though spectrum sensing can constitute a solid base to accomplish the reconfigurability and awareness goals of next generation networks, a new perspective is required to benefit from all of the dimensions of the available electro (or spectrum) hyperspace, beyond frequency and time. Therefore, spectrum sensing should evolve to a more general and comprehensive awareness-providing mechanism, not only as part of CR systems but also as a communication environment-awareness component of an ASHA paradigm that can adapt sensing parameters autonomously to ensure robust signal identification, parameter estimation, and interference avoidance. Such an approach will lead to recognition of communication opportunities in different dimensions of the spectrum hyperspace, and provide necessary information about the air interfaces, access techniques, and waveforms that are deployed over the monitored spectrum to accomplish ASHA resource and interference management. [ABSTRACT FROM AUTHOR]

In this paper, we present bi-directional data vortex interconnection network in which the packets are routed both in the forward as well as in the reverse directions. We have simulated the hardware model of a single node with data flow from the node in both the directions and routing. The cascading performance of nodes has been studied by varying the input power from -15 to 0 dBm and BER characteristics up to 70 cascaded nodes have been verified. The terminal reliability analysis of bi-directional data vortex is carried out, as reliability and fault tolerance are important parameters for any multistage interconnection network. Finally, the comparison of the terminal reliability between the proposed bidirectional architecture with two data vortex networks connected in parallel for bidirectional operation is presented. [ABSTRACT FROM PUBLISHER]

In this paper we present a decoding algorithm for multiple-input multiple-output (MIMO) communications. The algorithm is based on the QRD-QLD algorithm (see, e.g., Radosavljevic et al. 2012), proposes an improved path metric computation, and achieves a low probability of error which is close to the single tree search sphere decoder, at low implementation complexity. The proposed improved path metric computation increases the reliability of combining the results of the partial searches into sequences representing the maximum likelihood (ML) and the counter ML hypotheses in soft input MIMO decoding. The excellent performance of the improved algorithm are demonstrated via numerical simulations. [ABSTRACT FROM PUBLISHER]

A fundamental problem when locating sensors in a network is to reliably estimate the distance between pairs of sensors. Since security of sensor networks is vulnerable in the wireless environment, this paper proposes a device-based ranging and node identification scheme, which can be applied to provide secure position information for wireless sensor applications. By generalizing the asynchronous distance estimation technology (distance estimation via asynchronous clocks), a device-based distributed distance estimation method is presented. Moreover, based on the physical property of a device, the communication delay (e.g., internal component delay, difference of the clocks, and response delay) between two wireless sensors may be used to identify the normal wireless sensors, to renew the network node information, and to enhance the reliability of distance estimation. The proposed device-based asynchronous ranging and node identification algorithm is shown to be feasible for identifying malicious sensor nodes in the network and is superior to the delay attack-resilient clock synchronization scheme with regard to the successful detection rate of antinodes and ranging accuracy. [ABSTRACT FROM PUBLISHER]

Existing approaches to diagnosing sensor networks are generally sink based, which rely on actively pulling state information from sensor nodes so as to conduct centralized analysis. First, sink-based tools incur huge communication overhead to the traffic-sensitive sensor networks. Second, due to the unreliable wireless communications, sink often obtains incomplete and suspicious information, leading to inaccurate judgments. Even worse, it is always more difficult to obtain state information from problematic or critical regions. To address the given issues, we present a novel self-diagnosis approach, which encourages each single sensor to join the fault decision process. We design a series of fault detectors through which multiple nodes can cooperate with each other in a diagnosis task. Fault detectors encode the diagnosis process to state transitions. Each sensor can participate in the diagnosis by transiting the detector's current state to a new state based on local evidences and then passing the detector to other nodes. Having sufficient evidences, the fault detector achieves the Accept state and outputs a final diagnosis report. We examine the performance of our self-diagnosis tool called TinyD2 on a 100-node indoor testbed and conduct field studies in the GreenOrbs system, which is an operational sensor network with 330 nodes outdoor. [ABSTRACT FROM PUBLISHER]

We consider two-way relay (TWR) networks consisting of two communicating nodes and multiple relays built upon orthogonal frequency-division multiplexing signaling. For low-cost implementation of relays, two pragmatic TWR protocols are proposed based on analog network coding (ANC). The proposed two-phase (2P)- and three-phase (3P)-ANC schemes employ time-domain instantaneous power scaling and relay selection to improve the outage performance without equipping discrete Fourier transform (DFT) and inverse DFT functions at the relay. In particular, we devise a relay power allocation factor and a resultant relay selection metric for the proposed 3P-ANC scheme, which can be implemented at low complexity. For the proposed schemes, the outage probability and achievable diversity order are also analyzed, which reveals a larger diversity order of the 3P-ANC scheme than the 2P-ANC scheme. The results from analysis and simulation show that the proposed schemes outperform the conventional 2P-ANC schemes employing time-domain average power scaling and distributed space-time block coding or frequency-domain power scaling and relay selection. [ABSTRACT FROM PUBLISHER]

This paper tackles the issue of reliable transport in delay-tolerant mobile ad hoc networks (DTNs) that are operated by some opportunistic routing algorithm. We propose a reliable transport mechanism that relies on acknowledgements (ACKs) and coding at the source. The various versions of the problem depending on buffer management policies are formulated and a fluid model based on mean-field approximation is derived for the designed reliable transport mechanism. This model allows both the mean file completion time and the energy consumption to be expressed up to the delivery of the last ACK at the source. The accuracy of this model is assessed through numerical simulations and a detailed investigation of the impact of the system parameters on the performance is conducted. We eventually present a joint optimization of the mean completion delay with or without an energy constraint, to identify the optimal set of parameters to use. [ABSTRACT FROM PUBLISHER]

Simultaneous wireless information and power transfer (SWIPT) is able to prolong the lifetime of energy constrained wireless networks. In this paper, we consider the relay beamforming design problem for SWIPT scheme in a non-regenerative two-way multi-antenna relay network. Our objective is to maximize the sum rate of two-way relay network under the transmit power constraint at relay and the energy harvesting (EH) constraint at EH receiver. For the non-convex EH-constrained relay beamforming optimization problem, we propose an iterative algorithm to find the global optimal solution based on semidefinite programming and rank-one decomposition theorem. To reduce computational complexity of global optimal solution, we transform the EH-constrained optimization problem to a difference of convex programming and propose a constrained concave convex procedure based iterative algorithm to find a local optimum. To further reduce the complexity, we propose a suboptimal solution based on the generalized eigenvectors method. When the case of multi-antenna sources is considered, we propose the alternating optimization based iterative algorithms. It is shown from simulations that considering the EH constraint, our proposed schemes outperform conventional relay beamforming schemes in the literature. [ABSTRACT FROM PUBLISHER]

For the requirements of energy saving in wireless sensor networks (WSNs), this study proposes a transmission power control strategy for cluster heads (CHs) based on multi‐packet reception in clustering WSNs. First, this study proposes a new CHs selection algorithm for clustering WSNs. Second, transmission power levels of each CH are determined according to the number of CHs in monitoring area. Third, with restrictions of successive interference cancellation algorithm in sink, transmission power control strategy for CHs are determined by distance from CHs to sink and residual energy of CHs. For whole network, single‐hop communication mode is designed to send data from sensor nodes to CHs, at the same time; it is also applied to send data from CHs to sink. Simulation results show that this power control strategy can reduce the energy consumption of sensor nodes and increase network throughput, which can greatly improve network lifetime. The authors believe that their findings will be useful guidelines for moving forward with successive interference cancellation research in WSNs. [ABSTRACT FROM AUTHOR]

Several approaches have been proposed to increase the lifetime of a wireless sensor network (WSN) while preserving full coverage of the sensed area. Most of them employ protocols to reduce the energy consumption by switching the sensors off. To correctly decide the set of nodes to switch off without losing the full network coverage, these techniques must guarantee that all nodes have up‐to‐date information about their neighbours. Considering a static WSN, the only important information which must be regularly advertised is the energy level of the nodes. This information is exchanged between nodes in fixed time slots through one‐hop messages. Nevertheless, the energy spent to transmit one simple bit of information is as the same used to process hundreds of transactions in a typical sensor. Thus, reducing the communication between nodes leads to an increase in the energy saving. This study proposes the unadvertised round energy saving (u‐REST) algorithm which eliminates the energy level advertise messages, thus conserving a huge amount of energy. u‐REST is able to increase the energy savings by deciding the set of nodes which can be switched off while preserving full area coverage without using energy level advertise messages. Mathematical proofs demonstrate that u‐REST ensures a full coverage of the interest area while saving energy. In fact, it is mathematically demonstrated that the worst case for energy savings in u‐REST is able to preserve more energy than the best case of all synchronisation‐based methods. [ABSTRACT FROM AUTHOR]

Ultra‐wideband (UWB) technology can offer very efficient solutions for various vehicular communication applications. The authors propose to use this technique to establish vehicle‐to‐vehicle and vehicle‐to‐infrastructure communications. In fact, compared to traditional carrier‐based technology, UWB is a carrierless system that implements new paradigms in terms of signal generation and reception. Thus, designing a UWB communication system requires the understanding of a mechanism which allows us to have wide bandwidth and very low transmitted powers used jointly to provide a reliable radio link. UWB offers potential transceiver systems with very simple implementations. Two approaches have emerged, which meet all the communication requirements: impulse and multi‐band systems. The present work relies on the first approach. So, the authors propose to use orthogonal functions called modified Gegenbauer functions (MGF) in the UWB system. Different scenarios are studied and compared in the scope of a system offering communication for subway trains. The authors propose a new receiver for the MGF‐UWB communication system. To evaluate the performances of the proposed communication system, the bit error rate values are calculated and analysed in the presence of multi‐user interference, considering synchronous and asynchronous cases. This study shows that this new receiver offers the required performance, for our UWB communication in transport systems, better than the performance obtained using a conventional receiver. [ABSTRACT FROM AUTHOR]

The authors propose a novel traffic prediction method for the minimisation of packet delay in Ethernet passive optical networks. The method relies on traffic monitoring at the optical network units (ONUs) and utilises readily available traffic information to predict the accumulated burst size of each respective ONU in the following cycle. They demonstrate that a significant delay enhancement can be accomplished by reporting the predicted, rather than the current, burst size to the optical line terminal (OLT). The author's simulation results show that a delay improvement of over 25% can be expected by the proposed method without modifying the well‐established interleaved polling scheme with adaptive cycle time dynamic bandwidth assignment scheme at the OLT. [ABSTRACT FROM AUTHOR]

This paper presents a new color shift keying (CSK) modulation format for wireless visible light communication (VLC), based on four colors instead of the three colors used in the existing IEEE 802.15.7 CSK physical layer standard. The new four color system uses a novel intensity modulation and direct detection approach to realize a four-dimensional signaling scheme that uses the available color and signal spaces efficiently. The bit error rate evaluation of both the existing and proposed system shows that the new four color scheme achieves a significant 4.4-dB electrical SNR gain over the three color scheme for an additive white Gaussian noise channel. The performance of existing and proposed CSK systems is examined over a range of dispersive optical wireless channels including the channel crosstalk and insertion losses, which reveals that the four color CSK scheme is more power efficient and reliable than the three color scheme for a particular amount of delay spread that the optical wireless channel may have. [ABSTRACT FROM PUBLISHER]

A dual price-based congestion control (DPCC) mechanism for optical burst switching (OBS) networks is proposed in this paper, which can achieve an optimal rate-reliability tradeoff by allocating proper network traffic and resources based on the idea of network utility maximization (NUM). The DPCC uses the congestion and reliability prices and feedback information to dynamically adjust the users' data sending rate and the end-to-end data transmission reliability in an OBS network. The performance of DPCC is evaluated and analyzed through simulations. Results verify that DPCC works very well in terms of its convergence and optimality. Moreover, compared with TCP, DPCC can achieve a maximum network utility, a parameter which can be used to reflect the overall user satisfaction degree in a network. DPCC is scalable due to its distributed nature. [ABSTRACT FROM PUBLISHER]

Backup paths are usually pre-installed by network operators to protect against single link failures in backbone networks that use multi-protocol label switching. This paper introduces a new scheme called Green Backup Paths (GBP) that intelligently exploits these existing backup paths to perform energy-aware traffic engineering without adversely impacting the primary role of these backup paths of preventing traffic loss upon single link failures. This is in sharp contrast to most existing schemes that tackle energy efficiency and link failure protection separately, resulting in substantially high operational costs. GBP works in an online and distributed fashion, where each router periodically monitors its local traffic conditions and cooperatively determines how to reroute traffic so that the highest number of physical links can go to sleep for energy saving. Furthermore, our approach maintains quality-of-service by restricting the use of long backup paths for failure protection only, and therefore, GBP avoids substantially increased packet delays. GBP was evaluated on the point-of-presence representation of two publicly available network topologies, namely, GÉANT and Abilene, and their real traffic matrices. GBP was able to achieve significant energy saving gains, which are always within 15% of the theoretical upper bound. [ABSTRACT FROM PUBLISHER]

We propose and demonstrate a concept of photonics-aided coordination for multi-cell downlink transmissions. The concept targets reliable high-throughput applications for future-proof millimeter-wave small cells based on radio-over-fiber fronthaul. Based on the physical properties of millimeter waves and the phase and magnitude relationship during optoelectrical conversion, a photonics-aided coordination module is proposed, which adjusts the overall channel matrix of optical wireless transmissions in order to achieve a distortion-free reception. Exploiting the multitude and density of remote access units, we specifically propose three methods of coordination, namely, photonics-aided amplification, synthesis, and interference cancellation, which directly enhance the signal-to-noise ratio, increase the throughput, and mitigate the interference of cell-edge users, respectively. These methods are realized at the physical layer and can be transparent to data, which reduces the coordination overhead. Prototypes, involving end-to-end downlink transmissions, are established, which demonstrate the feasibility and effectiveness of the proposed methods for both scalar and vector signals. [ABSTRACT FROM PUBLISHER]

Many applications of wireless sensor network (WSN) require the execution of several computationally intense in-network processing tasks. Collaborative in-network processing among multiple nodes is essential when executing such a task due to the strictly constrained energy and resources in single node. Task allocation is essential to allocate the workload of each task to proper nodes in an efficient manner. In this paper, a modified version of binary particle swarm optimization (MBPSO), which adopts a different transfer function and a new position updating procedure with mutation, is proposed for the task allocation problem to obtain the best solution. Each particle in MBPSO is encoded to represent a complete potential solution for task allocation. The task workload and connectivity are ensured by taking them as constraints for the problem. Multiple metrics, including task execution time, energy consumption, and network lifetime, are considered a whole by designing a hybrid fitness function to achieve the best overall performance. Simulation results show the feasibility of the proposed MBPSO-based approach for task allocation problem in WSN. The proposed MBPSO-based approach also outperforms the approaches based on genetic algorithm and BPSO in the comparative analysis. [ABSTRACT FROM PUBLISHER]

Coverage is a vital issue that ensures that basic functions are available in wireless sensor networks (WSNs). These functions provide communications during emergency rescue or in war environments. Sensor nodes must be dispersed and survive in place for a long time in order to accurately monitor all events. However, sensor nodes rely on limited battery energy restricted to the lifetime of the entire network. When few sensor nodes are awake during an epoch, the entire network lifetime becomes longer. This implies that the coverage problem must be solved based on the energy efficiency issue. In order to strengthen the coverage ratio with a limited number of sensor nodes, practical coverage algorithms were proposed in the existing researches but investigated in a 2-D plane, which is not suitable for a realistic environment. Few researchers have investigated the WSN coverage problem for a 3-D space. The actual terrain is rugged and bumpy that prevents deploying sensor nodes in three-dimension space. In this paper, we consider the field of interest as a complex surface but also use the spline function to obtain factual information about a complex surface. Furthermore, dynamic programming is utilized to optimize the sensing radius for reducing the power consumption. [ABSTRACT FROM PUBLISHER]

Over the last couple of decades, clustering‐based protocols are believed to be the best for heterogeneous wireless sensor networks (WSNs) because they work on the principle of divide and conquer. In this study, the authors propose and evaluate two new clustering‐based protocols for heterogeneous WSNs, which are called single‐hop energy‐efficient clustering protocol (S‐EECP) and multi‐hop energy‐efficient clustering protocol (M‐EECP). In S‐EECP, the cluster heads (CHs) are elected by a weighted probability based on the ratio between residual energy of each node and average energy of the network. The nodes with high initial energy and residual energy will have more chances to be elected as CHs than nodes with low energy whereas in M‐EECP, the elected CHs communicate the data packets to the base station via multi‐hop communication approach. To analyse the lifetime of the network, the authors assume three types of sensor nodes equipped with different battery energy. Finally, simulation results indicate that the authors protocols prolong network lifetime, and achieve load balance among the CHs better than the existing clustering protocols. [ABSTRACT FROM AUTHOR]

With the recent prevalence of Internet protocol-based services, packet traffic is rapidly becoming the mainstream of data traffic. This has increased the demand for transport network technology that can efficiently accommodate the large capacity of both packet-based and circuit-based traffic while achieving high reliability, sufficient operation, and maintenance capability comparable to that of traditional transport networks such as synchronous digital hierarchy or optical transport networks. This study gives an overview of packet transport technologies including Ethernet and multiprotocol label switching (MPLS), and provides details of MPLS-TP (transport profile), recently developed as a promising next-generation packet transport technology. Its standardization in International Telecommunication Union, Telecommunication Standardization Sector and Internet Engineering Task Force is also described. Then, further perspectives are given on MPLS-TP applications including layer convergence of transport networks for cost-effective and simple operation. [ABSTRACT FROM PUBLISHER]

As virtualization is becoming a promising way to support various emerging application, provisioning survivability to requested virtual networks (VN) in a resource efficient way is important. In this paper, we investigate the survivable VN embedding (SVNE) problem from a new perspective. First, we consider the failure dependent protection (FDP) in which each primary facility node would have a different backup facility node, as opposed to the Failure Independent Protection (FIP) which has been studied before, in order to provide the same degree of protection against a single node failure with less substrate resources. Secondly, we enhance the VN with additional computing and communication resources and design the Enhanced VN (or EVN) before embedding it to the substrate in order to further reduce the amount of substrate resources needed to survive a single facility node failure. The work is the first that combines the FDP with EVN design (FD-EVN) to explore a resource efficient solution to the SVNE problem. After presenting a binary quadratic programming (BQP) formulation of the FD-EVN design problem and a Mixed Integer Linear Programming (MILP) formulation of the EVN embedding (EVNE) problem, we propose two heuristic algorithms for FD-EVN design, as well as an EVNE algorithm that explores primary and backup substrate resources sharing. Simulations are conducted to evaluate the performance of the solutions to the BQP/MILP formulation when possible, and the heuristics. The proposed FD-EVN approach has shown to be resource efficient and in particular, outperform other approaches in terms of request acceptance ratio and embedding cost, although as a tradeoff, requiring more service migration after failures. [ABSTRACT FROM PUBLISHER]

The concept of D-spectrum is a useful tool to investigate the reliability and stochastic properties of networks. In this paper, we consider a network consisting of n components (links or nodes), and assume that the network has two states: up, and down. We study the D-spectrum-based reliability of the network under the assumption that the components are subject to failure according to a counting process. Mixture representation of the reliability of the network lifetime is given in terms of the reliability functions of arrival times. It is shown that, when the D-spectra of two networks are stochastically ordered, then under some conditions the lifetimes of two networks are also stochastically ordered. Under the special case when the process of the failure of the components is a nonhomogeneous Poisson process, we arrive at a mixture representation for the reliability function of the network lifetime, and explore several stochastic and aging properties of the network lifetime under different scenarios. The failure rate of the network lifetime and its asymptotic behavior is investigated. D-spectrum based representation theorems are also given on the basis of the stochastic precedence concept. [ABSTRACT FROM AUTHOR]

In wireless sensor networks (WSNs) having a high density of sensor nodes, transmitted measurements are spatially correlated, often redundantly whenever an event of interest is detected. In this work, the authors propose a correlation model to enable energy‐efficient methodologies that exploit the spatial correlation at the network and medium access control (MAC) layers. At the network layer, the authors first demonstrate how, through proper tuning of both the sensing range and correlation threshold, WSNs can be partitioned into disjoint correlated clusters without degrading the information reliability, thus enabling significant energy saving. On the other hand, as another contribution, the authors investigate the impacts of correlation between nodes on achieved distortion in the event estimation at the sink. The interactions among various parameters such as distortion constraints, spatial node density, node selection, sensing range and their impacts on the reconstruction performance are quantitatively studied. The authors demonstrate that the same level of distortion constraint can be achieved by selecting fewer nodes. The nodes can be still fewer if they are less spatially correlated. However, the MAC protocols which show distributive effect of this selection needs more study. [ABSTRACT FROM AUTHOR]

Recently, there are much research on wireless body sensor network (WBSN) as the growing demands of pervasive health and personal entertainment. Supporting high‐speed data transmission becomes a challenge in development of WBSN in medical and entertainment applications. In this study, the authors present ZebraBAN, a high‐speed low‐power WBSN based on single‐carrier ultra‐wideband (SC‐UWB) and IEEE 802.15.4. The heterogeneous network combines the strengths of SC‐UWB and IEEE 802.15.4 technologies while offsetting their weakness. Like SC‐UWB, the system achieves medium to high data rate and reduces radiation and power consumption at a low cost. Like IEEE 802.15.4, ZebraBAN achieves low data rate and low latency under low contention. In ZebraBAN, the authors introduce the idea of control plane and data plane for controlling multiple PHYs and MACs according to energy and data rate balance. Experimental results based on the prototype system are presented to evaluated the network performance. The result demonstrates that high reliability transmission for every sensor data stream within 4 m around the person, with a low‐power consumption for fabricated application specific integrated circuits (ASIC) about 8.2 mW when it works on transmitting one channel video. The network has a peak capacity of 100 Mbps that could support multiple sensor nodes, including four channel video stream and multiple low‐speed sensor datas. [ABSTRACT FROM AUTHOR]

In recent years, following the deployment of wavelength division multiplexing networks, fault detection and localisation has become a challenging issue in networks with high reliability. Optical layer monitoring schemes based on monitoring trails (m ‐trail) are considered an efficient way to localise a single fault unambiguously in all‐optical networks. In spite of the extensive work on the m ‐trail concept, the issue has not been validated from the feasibility point of view. Previous works on the m ‐trail monitoring scheme have focused mainly on algorithm design for minimising the number of monitors, however, none of them have observed that length limitations should be considered as well. The authors investigate the physical constraints of launching m ‐trails, mainly focusing on the maximum length that each m ‐trail may have and describe an algorithm that solves the length constrained m ‐trail formulation problem. Numerous simulations were implemented in a physical layer simulator for observing qualitative parameters in different m ‐trail lengths. The authors propose 15 000 km as a length limit for each m ‐trail for out‐of‐band monitoring. Finally, an algorithmic solution is provided for monitoring trail design problem satisfying these physical constraints. [ABSTRACT FROM AUTHOR]

The random linear network coding was proposed as an adoptable coding technique for many practical communication networks. This study focuses on analysing the failure probabilities of random linear network coding to study its performance for multicast network, emphatically some known upper bounds of the failure probabilities have been improved and the worst cases are indicated for these bounds. Besides, if the more network topology information is achieved, the better upper bounds can be obtained. Furthermore when the field size goes to infinity the limit behaviours of the failure probabilities are discussed. [ABSTRACT FROM AUTHOR]

As the Internet takes an increasingly central role in the authors communications infrastructure, the slowness of routing convergence after network failure is becoming a significant problem in the current link‐state‐based routing protocol. There is an alternative approach, which is to compute backup routes that allow the failure to be repaired locally by the routers that detect the failure without informing other routers of the failure immediately. Failure insensitive routing (FIR) adopts this approach, in which packet forwarding is based on not only the destination but also the link it arrives from. However, FIR faces two problems. First, a packet may travel an unnecessary path, which degrades resource utilisation efficiency. Second, FIR may fail to set a re‐route path even though an active path is available. This study proposes a resilient routing scheme that avoids these two problems by enhancing FIR. It is named smart FIR (S‐FIR). Upon failure, S‐FIR employs a backup routing table based on the unexpected link from which a packet arrives so that subsequent packets can be forwarded to a different next hop to avoid roll back, whereas the original FIR forwards every packet based on the current working routing table. Numerical results indicate that S‐FIR reduces the path length significantly, compared with the original FIR. In addition, in case of any link failure, S‐FIR is proven to guarantee that any packet reaches its destination as long as there is a valid path. S‐FIR provides more robust routing than FIR. [ABSTRACT FROM AUTHOR]

Multicell cooperation (MCC) is an approach for mitigating intercell interference in dense cellular networks. Existing studies on MCC performance typically rely on either oversimplified Wyner-type models or complex system-level simulations. The promising theoretical results (typically using Wyner models) seem to materialize neither in complex simulations nor in practice. To more accurately investigate the theoretical performance of MCC, this paper models an entire plane of interfering cells as a Poisson random tessellation. The base stations (BSs) are then clustered using a regular lattice, whereby BSs in the same cluster mitigate mutual interference by beamforming with perfect channel state information. Techniques from stochastic geometry and large-deviation theory are applied to analyze the outage probability as a function of the mobile locations, scattering environment, and the average number of cooperating BSs per cluster \ell . For mobiles near the centers of BS clusters, it is shown that outage probability diminishes as O(e^- \ell ^\nu 1) with 0\leq \nu 1\leq 1 if scattering is sparse, and as O(\ell ^-\nu 2) with \nu 2 proportional to the signal diversity order if scattering is rich. For randomly located mobiles, regardless of scattering, outage probability is shown to scale as O(\ell ^-\nu 3) with 0\leq \nu 3 \leq 0.5. These results confirm analytically that cluster-edge mobiles are the bottleneck for network coverage and provide a plausible analytic framework for more realistic analysis of other multicell techniques. [ABSTRACT FROM PUBLISHER]

A common measure of performance of a reliable network, i.e., a network in which elements are failure prone, is the expected value of the maximum s-t flow between a pre-specified source node s and a pre-specified terminal node t in the network. The problem of determining the expected value of maximum s-t flow is computationally hard. Therefore, for practical sized networks, it is estimated through Monte Carlo based simulation methods which estimate the measure by evaluating the maximum flows in a large sample of network states. Such methods are computationally expensive. In this paper, we present an algorithm which speeds up the process of evaluating maximum flows in the sampled states by a factor of three on two difficult classes of randomly generated networks. This speed-up allows us to compute the measure for larger networks than is currently possible. It also allows us to obtain more accurate estimates on similar sized problems within similar execution times. [ABSTRACT FROM PUBLISHER]

In this paper, a system of systems (SoS) framework for the reliability analysis of telecommunication networks is proposed. In this framework, two hazard analysis techniques, hazard and operability analysis and fault tree analysis, are combined in a hybrid scheme. This is further enhanced using the Bayesian network model along with sensitivity analysis in order to answer complex probability queries and to estimate the impact of residual mishap risks, unknown events, or events that cannot easily be modeled. The SoS emergent behavior is further revealed using exploratory modeling. The proposed SoS framework is applied in the case of a fiber-to-the-curb VDSL telecommunication network. [ABSTRACT FROM PUBLISHER]

Integration of miniature sensors composes a wireless body area network (WBAN), which enables remote health monitoring. To make this technology widely acceptable in the society, some studies suggest commonly used gadgets such as cell phones or laptops as a hub for WBANs. In these cases, envisaged medical and non‐medical applications of WBANs must have the same priority unless in emergency situations. Also, medical applications of WBANs need some strict requirements that are not that important for non‐medical applications, such as very low‐power consumption or reliability. In addition, channel condition may change in WBANs because of fading effects and this causes packet loss. Therefore proper traffic prioritisation, high reliability and efficient channel utilisation are vitally important issues in these networks. In this study, the authors improve the performance of the medium access control (MAC) protocol of WBANs using an adaptive resource allocation and traffic prioritisation according to the medical situation of user and channel condition. Through adaptively separating and managing the possible traffics of WBANs, the heterogeneous requirements of different applications are provided. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 and IEEE 802.15.6 MAC protocols in terms of power consumption as well as the channel utilisation and reliability. [ABSTRACT FROM AUTHOR]