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Summary: In this paper, the problem of pinning synchronization for delayed complex directed networks via generalized intermittent adaptive control strategy is considered. First, a dynamical mode of delayed network is investigated. Second, a generalized intermittent adaptive control strategy which unified the traditional periodic intermittent control and the aperiodic case is introduced. Additionally, by constructing a piecewise Lyapunov auxiliary function and making use of piecewise analysis technique, some effective and novel criteria to ensure the global synchronization of delayed complex networks based on the designed control protocols are obtained. Finally, an example with numerical simulations is provided to demonstrate the validness of the theoretical results proposed scheme. [ABSTRACT FROM AUTHOR]

In this study, the distributed event-triggered control strategy is found to cope with the pinning control problem of stochastic discrete-time complex networks with time-varying delay. Under the devised mechanism, exponential mean-square synchronisation can be implemented in the directed networks. By utilising the Lyapunov functional method and the stochastic analysis, several sufficient conditions are established. Moreover, the issue of average synchronisation is investigated. For the stochastic complex networks without reference state, it is demonstrated that all nodes can converge to a time-varying weighted average exponentially by a suitable distributed event-triggered controller. Finally, some numerical examples are presented to indicate the effectiveness of the devised control strategies. [ABSTRACT FROM AUTHOR]

Cloud computing has great economical advantages and wide application, more and more data owners store their data in the cloud storage server (CSS) to avoid tedious local data management and insufficient storage resources. But the privacy of data owners faces enormous challenges. The most recent searchable encryption technology adopts the ciphertext-policy attribute-based encryption (CP-ABE), which is one good method to deal with this security issue. However, the access attributes of the users are transmitted and assigned in plaintext form. In this paper, we propose a based on blinded CP-ABE searchable encryption cloud storage service (BCP-ABE-SECSS) scheme, which can blind the access attributes of the users in order to prevent the collusion attacks of the CSS and the users. Data encryption and keyword index generation are performed by the data owners; meanwhile, we construct that CSS not only executes the access control policy of the data but also performs the pre-decryption operation about the encrypted data to solve higher time cost of decryption calculation to the data users. Security proof results show that this scheme has access attribute security, data confidentiality, indistinguishable security against chosen keyword attack, and resisting the collusion attack between the data user and the CSS. Performance analysis and the experimental results show that this scheme can effectively reduce the computation time cost of the data owners and the data users. [ABSTRACT FROM AUTHOR]

Summary: To provide privacy protection in mobile health care system, medical users typically encrypt their personal health information before publishing it to the health care center. And other medical users download, decrypt, and process it using an access control protocol. However, current access control protocols are mainly focusing the privacy of personal health information and lacking the protection for medical users' real identities, leading to a variety of security issues. At the same time, current access control protocols for mobile health care systems are usually based on bilinear map, resulting in high computation costs. Observing the above issues, we introduce a novel access control protocol with privacy‐preserving called Access Control for Mobile Healthcare System (ACMHS). Similar to protocols of this field, ACMHS can provide privacy protection for mobile health care systems. However, different from other well‐known approaches, ACMHS uses pseudonyms instead of real identities, which can provide privacy protection for medical users' real identities. Moreover, to reduce the computation cost of bilinear map, we introduce the algebraic signature to ACMHS and design a novel access control protocol, which is much more efficient than current bilinear‐map‐based protocols. By doing so, ACMHS can achieve high efficiency while still enjoying required security requirements. Experimental results show that ACMHS is feasible for real‐world applications. [ABSTRACT FROM AUTHOR]

Summary: An efficient cryptography mechanism should enforce an access control policy over the encrypted data to provide flexible, fine‐grained, and secure data access control for secure sharing of data in cloud storage. To make a secure cloud data sharing solution, we propose a ciphertext‐policy attribute‐based proxy re‐encryption scheme. In the proposed scheme, we design an efficient fine‐grained revocation mechanism, which enables not only efficient attribute‐level revocation but also efficient policy‐level revocation to achieve backward secrecy and forward secrecy. Moreover, we use a multiauthority key attribute center in the key generation phase to overcome the single‐point performance bottleneck problem and the key escrow problem. By formal security analysis, we illustrate that our proposed scheme achieves confidentiality, secure key distribution, multiple collusions resistance, and policy‐ or attribute‐revocation security. By comprehensive performance and implementation analysis, we illustrate that our proposed scheme improves the practical efficiency of storage, computation cost, and communication cost compared to the other related schemes. [ABSTRACT FROM AUTHOR]

Authentication and key agreement (AKA) is a challenge-response-like security protocol that uses symmetric-key cryptography to establish authenticated keys between 2 parties. Its application in the third-generation mobile system universal mobile telecommunications system (UMTS) is called UMTS-AKA, and the version applied in the fourth-generation mobile communication system long-term evolution (LTE) is called LTE-AKA. Both UMTS-AKA and LTE-AKA share the same weakness: the network operators need to maintain a large space of authentication vectors for visiting stations, and the transmission of the vectors causes lots of overhead. This weakness will be amplified when there are billions of devices accessing the network in the Internet-of-things scenarios. In addition, these schemes provide only key distribution (not key agreement) and cannot provide session key forward secrecy. In this paper, we propose a range-bound key assignment technique to tackle the challenges. The proposed scheme drastically reduces the communication overhead and greatly strengthens the security robustness. The securities are analyzed and are verified using the AVISPA toolset. [ABSTRACT FROM AUTHOR]

Address Resolution Protocol (ARP) is an essential protocol for the operation of local area networks. It is used for mapping the logical address to the physical address. However, ARP was designed without any security features. Therefore, ARP is vulnerable to many ARP spoofing attacks, such as the host impersonation, man-in-the-middle (MITM), and denial of service (DoS) attacks. Many techniques were introduced in the literature for mitigating ARP spoofing attack. However, they could not provide protection against the host impersonation and DoS attacks. This work introduces a new technique to secure address resolution protocol called ARP Authentication (ARP-A). The proposed technique provides authentication for ARP messages and entities. In addition, it converts ARP from a stateless to a stateful protocol. To evaluate the performance of ARP-A, it was implemented on Linux. To investigate the scalability of ARP-A, a new analytical model was designed for it using stochastic reward nets. The results show that, compared with other related schemes introduced in the literature, ARP-A is more efficient in terms of security and performance. [ABSTRACT FROM AUTHOR]

With its simplicity and feasibility, password-based remote user authentication becomes a popular way to control remote access to network. These years, numerous password-based authentication schemes have been proposed. Recently, Maitra et al proposed a smart card-based scheme which claims to be resistant to various attacks. Unfortunately, we found some important flaws in this scheme. Therefore, in this paper, we will demonstrate that the scheme of Maitra et al is not secure enough as claimed: neither resisting against off-line password guessing attack and insider attack nor preserve forward secrecy. To overcome those flaws, we put forward an improved new scheme which not only is resistant to all known attacks but also provides many attractive attributes, such as user revocation and re-register. Also, we compared the scheme with other related schemes, the result proved the superiority of our scheme. Particularly, we show a new way (beyond the conventional Deffie-Hellman approach) to achieve forward secrecy. Furthermore, we put some efforts into exploring the design principle of authentication schemes. [ABSTRACT FROM AUTHOR]

In this paper, medium access control (MAC) sublayer data traffic scheduling in distributed networked control systems (DNCSs) with networked induced packet losses and delays is investigated for stabilization and control of system dynamics. An effective-information-directed distributed sensor selection algorithm is proposed to select sensors to participate in delay-tolerant information filtering for state estimation. The distributed scheduling algorithm is based on the total amount of effective information for all measurements stored in the sensors. We consider packet loss in wireless networks as a special type of delay, so the impact of packet losses on effective information amount can also be studied for the formulation of distributed scheduling strategy in the presence of packet losses. The distributed data traffic scheduling considering packet losses and delays is carried out in a networked system with data packet dropout governed by a Markov process for voltage regulation and stabilization with distributed energy resources (DERs). Experimental results demonstrate that the scheduling algorithm with awareness of the system dynamic state can well control the power system dynamics. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Many Java applications instantiate objects within the Java heap that are persistent but seldom if ever referenced by the application. Examples include strings, such as error messages, and collections of value objects that are preloaded for fast access. This paper describes a stack-based framework for detecting these 'cold' objects at runtime, with a view to marshaling and sequestering them in designated regions of the heap where they may be preferentially paged out to a backing store, thereby freeing physical memory pages for occupation by more active objects. Furthermore, we evaluate the correctness and efficiency of stack-based approach with an access barrier. The experimental results from a series of SPECjvm2008 benchmarks are presented. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Densifying the communications network and integrating innovative technologies leads to increased power consumption (PC), along with increased signalling and degraded scalability. The latter can be mitigated by using software defined networks, while cloud radio access network (C-RAN) reduces the PC. Since evaluating and improving the PC is an important key success factor for the upcoming fifth generations, a reliable power model (PM) is required. This study proposes a componentised, linear and parameterised PM, and explores the individual components relevant for PC analysis, particularly for software defined C-RAN (SDC-RAN) architecture. The model quantifies the energy efficiency (EE) by capturing the PC of individual components, and measures the amount of PC in the network. Cooling and total PC of C-RAN and SDC-RAN for different parameters such as varying numbers of antennas and different system's bandwidth share has also been considered. The results show that SDC-RAN increases the total PC by about 20% compared with C-RAN. Additionally, the study shows the results of modelling the participating core network's control plane unit's PC along with establishing the accuracy of the components and the parameterised models. [ABSTRACT FROM AUTHOR]

Next generation wireless networks consist of many heterogeneous access technologies that should support various service types with different quality of service (QoS) constraints, as well as user, requirements and provider policies. Therefore, the need for network selection mechanisms that consider multiple factors must be addressed. In this paper, a network selection method is proposed by applying the analytic network process to estimate the weights of the selection criteria, as well as a fuzzy version of technique for order preference by similarity to ideal solution to perform the ranking of network alternatives. The method is applied to a heterogeneous network environment providing different QoS classes and policy characteristics. Each user applies the method to select the most appropriate network, which satisfies his or her requirements in respect of his or her service-level agreement (SLA). Performance evaluation shows that when the user requests only one service, the proposed method performs better compared to the original technique for order preference by similarity to ideal solution, as well as the Fuzzy AHP-ELECTRE method. Moreover, the proposed method can be applied in cases where a user requires multiple services simultaneously on a device. The sensitivity analysis of the proposed method shows that it can be properly adjusted to conform to network environment changes. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we address the problem of interference when multiple time division multiple access-based wireless body area networks (WBANs) come in the proximity of one another. We propose a simple solution that creates common non-conflicting schedule between these interfering WBANs. Our proposed scheme allows the reuse of maximum possible time slots among WBANs that are two-hop neighbors of one another. A flow admission control scheme is applied to control the flows during the period of interference. We show that the percentage of flows admitted because of flow control decreases with the increase in the network size and flow rate. We simulated a scenario where WBANs move randomly within a simulation area with a certain speed and meet at a particular point. We show that the signal to interference noise ratio (SINR) value of WBANs changes as long as they are within the transmission range of one another. Also, we show that the exchanges of common schedule (which is dependent on the number of times the SINR value drops below the threshold) are required in order to improve the packet delivery ratio in WBANs. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new opportunistic cross-layer MAC protocol involving channel allocation and packet scheduling for cognitive radio networks is proposed. Cognitive radio allows secondary users (SUs) to exploit the available portions of the licensed spectrum bands without interfering with primary users. In particular, we consider a cognitive radio system, where SUs are equipped with two transceivers: a control transceiver and a software-defined radio transceiver. Data traffic characteristics of SUs are considered to ameliorate system performance. So, we propose a mechanism of resource reservation to improve QoS requirements that favors successful SUs to transmit data during x time slots without interfering with primary users. The key novelty of this paper is giving priority for SUs with important data traffic and which frequently solicits data channels to transmit for the remaining time of the ongoing time slot and for the next time slots directly after checking the channel availability. We develop a new analytical model to evaluate delay parameter for two scenarios with and without resource reservation and we then investigate the impact of those scenarios on the energy consumption. We show through simulations that cognitive radio performances increase noticeably with the proposed scheme. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the capture effect through experiments conducted with Iris nodes equipped with AT86RF230 radio transceivers. It is shown that the first arriving packet in a collision can capture the radio channel for equal power transmissions and may be decoded depending on the amount of overlap. A new 3-packet-capture scenario is introduced and implemented. To be able to understand the impact of capture on the throughput performance of wireless sensor networks, we present an analysis of the capture coefficient using our practical results. For real-world implementations, the throughput of pure ALOHA considering a finite number of users is presented in analytical form. The capture coefficient is then applied to pure ALOHA as a case study. Using analytical and practical implementations of the capture effect on ALOHA, a very good match in channel throughput performance enhancement is demonstrated over the non-capture effect case. TinyOS-2.x is used to program the nodes and to observe data exchange on a computer through a base station. [ABSTRACT FROM AUTHOR]

We propose a two-sided model with two competing Internet platforms, and a continuum of Content Providers (CP's). We study the effect of a net neutrality regulation on capacity investments in the market for Internet access, and on innovation in the market for content. Under the alternative discriminatory regime, platforms charge a priority fee to those CP's which are willing to deliver their content on a fast lane. We find that under discrimination, investments in broadband capacity and content innovation are both higher than under net neutrality. Total welfare increases, though the discriminatory regime is not always beneficial to the platforms as it can intensify competition for subscribers. As platforms have a unilateral incentive to switch to the discriminatory regime, a prisoner's dilemma can arise. We also consider the possibility of sabotage, and show that it can only emerge, with adverse welfare effects, under discrimination. [ABSTRACT FROM AUTHOR]

SUMMARY Considering the limitations of satellite communication systems and advantages of new emerging interleave-division multiple access (IDMA) technology, IDMA is introduced into the satellite systems, providing a new solution for multiple access techniques of satellite systems. To further validate the IDMA into satellite systems, a novel medium access control (MAC) scheme is proposed. In the random access channel, the interleave-division slotted ALOHA method is adopted to alleviate the collision of access requests. Furthermore, a novel minimum power allocation scheme based on signal-to-interference-plus-noise ratio (SINR) evolution is proposed to maximize the capacity of such an interference-sensitive system. By virtue of SINR evolution, our proposed scheme can accurately estimate multi-user detection efficiency with low computational cost and further reduce the transmitted power, illustrating the high power efficiency of IDMA. To further enhance the performance of the MAC protocol, an effective call admission control scheme considering the effect of power control error is designed and combined into our MAC protocol. Analysis and simulation results show that, by taking full advantage of the chip-by-chip multi-user detection technique, the proposed IDMA MAC protocol achieves high throughput and low average packet delay simultaneously, with low onboard processing complexity in the multi-beam satellite communication systems. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In ad hoc networks, directional antennas offer many benefits compared with classical omnidirectional antennas. Those include significant increases in spatial reuse, coverage range, and subsequently network capacity as a whole. Most of the proposed directional medium access control methods assume that all the nodes in the network have homogeneous antenna types. However, it is quite unusual that a sudden change will occur, and every laptop, palmtop, computer, and other similar device will be turned into a directional antenna holding device. There will always be a possibility of heterogeneous antenna used in the deployed nodes of the network. In this paper, we have proposed a medium access control protocol that deals with the new challenges introduced into heterogeneous networks in the form of deaf and hidden node problems. Using Optimized Network Engineering Tools 16.0, we have simulated three ad hoc network scenarios. These scenarios have different ratios of omnidirectional and directional nodes. We evaluated the performance of these scenarios by varying the ratio. We found that when we increase the directional nodes in the network, the performance increases. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes a multimedia streaming architecture that combines network and video technologies to handle video traffic over multi-hop access networks. In this context, resource overprovision typical of current quality of service approaches will become a limiting factor because of the increasing spread of bandwidth-intensive multimedia applications. The proposed scheme adopts a time-driven priority scheduling at network nodes and exploits slice classification at the video encoder to differentiate packets. The service guarantees offered by time-driven priority, together with the packet classification, significantly reduce congestion and increase the video quality at the receiver with respect to the traditional differentiated services (DiffServ) approach, also achieving high resource utilization. This is an important result, as current DiffServ-based architectures are far from obtaining such resource utilization in conjunction with reasonable delays and jitters. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Distributed network utility maximization (NUM) is receiving increasing interests for cross-layer optimization problems in multihop wireless networks. Traditional distributed NUM algorithms rely heavily on feedback information between different network elements, such as traffic sources and routers. Because of the distinct features of multihop wireless networks such as time-varying channels and dynamic network topology, the feedback information is usually inaccurate, which represents as a major obstacle for distributed NUM application to wireless networks. The questions to be answered include if distributed NUM algorithm can converge with inaccurate feedback and how to design effective distributed NUM algorithm for wireless networks. In this paper, we first use the infinitesimal perturbation analysis technique to provide an unbiased gradient estimation on the aggregate rate of traffic sources at the routers based on locally available information. On the basis of that, we propose a stochastic approximation algorithm to solve the distributed NUM problem with inaccurate feedback. We then prove that the proposed algorithm can converge to the optimum solution of distributed NUM with perfect feedback under certain conditions. The proposed algorithm is applied to the joint rate and media access control problem for wireless networks. Numerical results demonstrate the convergence of the proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The medium access control protocol determines system throughput in wireless mobile ad hoc networks following the ieee 802.11 standard. Under this standard, asynchronous data transmissions have a defined distributed coordination function that allows stations to contend for channel usage in a distributed manner via the carrier sensing multiple access with collision avoidance protocol. In distributed coordination function, a slotted binary exponential backoff (BEB) algorithm resolves collisions of packets transmitted simultaneously by different stations. The BEB algorithm prevents packet collisions during simultaneous access by randomizing moments at stations attempting to access the wireless channels. However, this randomization does not eliminate packet collisions entirely, leading to reduced system throughput and increased packet delay and drop. In addition, the BEB algorithm results in unfair channel access among stations. In this paper, we propose an enhanced binary exponential backoff algorithm to improve channel access fairness by adjusting the manner of increasing or decreasing the contention window based on the number of the successfully sent frames. We propose several configurations and use the NS2 simulator to analyze network performance. The enhanced binary exponential backoff algorithm improves channel access fairness, significantly increases network throughput capacity, and reduces packet delay and drop. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper describes an analytical model and an associated algorithm for assessing the throughputs of each host in wireless mesh networks (WMNs). It provides a framework for studying WMNs, particularly when the performance and parameters in multiple protocol layers have to be jointly evaluated and optimized. From the point of the implementation, a simple recursive formula with N − 1 iterations is used to obtain the throughput performance of N node WMNs. The produced expressions offer insights into understanding the performance of the individual nodes without referring to a specific medium access control layer or physical layer technology. The model serves as a general tool for capturing the characteristics of the WMNs. Using the model, the complexity of cross-layer studies is reduced, thus allowing researchers to focus on the modelling of other associated layers. The paper explains the rationale behind the model and provides examples of scenarios for which it is suitable. It is validated using discrete event simulations in the OPNET network simulator. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The statistical multiplexer problem was analyzed extensively in the discrete-time case within the context of ATM access networks or Internet. Despite the vast literature on ATM multiplexer, this problem has not been satisfactorily analyzed in the continuous-time case. In this paper, a statistical multiplexer consisting of a single server queue is modeled and analyzed. N identical interrupted Poisson process arrivals flow into the multiplexer are considered, the service time is assumed to be exponentially distributed, and the queue size is infinite. We developed an efficient way to approximate the superposition of n interrupted Poisson process (or n MMPP 2) arrival process by an MMPP 2 through moments and index of dispersion count (IDC) matching. We then find the closed-form Laplace transform of the departure process of an MMPP 2/M/1 queue. Our results prove that the departure process of an MMPP 2/M/1 queue is not an MMPP 2, which closes the long open problem that whether the departure process of an MMPP/M/1 can be a MMPP. Using Laplace transform matching, we approximated the departure process of an MMPP 2/M/1 by an MMPP 2. These results permit us to analyze a number of statistical multiplexer linked in series as they arise in an access network. Numerical experiments show that approximate analytical results match the simulation results very well. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Compared with omni-directional antennas, directional antennas have many merits, such as lower interference, better spatial reuse, longer transmission range, and improved network capacity. Directional antennas enable numerous emerging outdoor and indoor applications, which have been addressed in many recent studies. Despite the advances in wireless networks with directional antennas (DAWNs), there are many research challenges in all layers of DAWNs. This paper presents a detailed study on recent advances and open research issues on DAWNs. Firstly, we briefly introduce the classification of directional antennas, antenna radiation patterns, antenna modes, and the challenges in the physical layer of DAWNs. We then present research issues on the medium access control (MAC) layer, followed by the current solutions as well as open research problems on the MAC layer of DAWNs. In addition, we also discuss the research issues on the routing layer and the transport layer. Moreover, other research challenges on the performance evaluation of DAWNs and a brief introduction of indoor DAWNs are given in this paper as well. In conclusion, we summarize the current research issues on DAWNs as well as prospects in the future. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Following recent advances in the performance of ad hoc networks, the limited life of batteries in mobile devices poses a bottleneck in their development. Consequently, how to minimize power consumption in the Medium Access Control (MAC) layer of ad hoc networks is an essential issue. The power-saving mode (PSM) of IEEE 802.11 involves the Timing Synchronization Function to reduce power consumption for single-hop mobile ad hoc networks (MANETs). However, the IEEE 802.11 PSM is known to result in unnecessary energy consumption as well as the problems of overheating and back-off time delay. Hence, this study presents an efficient power-saving MAC protocol, called p-MANET, based on a Multi-hop Time Synchronization Protocol, which involves a hibernation mechanism, a beacon inhibition mechanism, and a low-latency next-hop selection mechanism for general-purpose multi-hop MANETs. The main purposes of the p-MANET protocol are to reduce significantly the power consumption and the transmission latency. In the hibernation mechanism, each p-MANET node needs only to wake up during one out of every N beacon interval, where N is the number of beacon intervals in a cycle. Thus, efficient power consumption is achieved. Furthermore, a beacon inhibition mechanism is proposed to prevent the beacon storm problem that is caused by synchronization and neighbor discovery messages. Finally, the low-latency next-hop selection mechanism is designed to yield low transmission latency. Each p-MANET node is aware of the active beacon intervals of its neighbors by using a hash function, such that it can easily forward packets to a neighbor in active mode or with the least remaining time to wake up. As a consequence, upper-layer routing protocols can cooperate with p-MANET to select the next-hop neighbor with the best forwarding delay. To verify the proposed design and demonstrate the favorable performance of the proposed p-MANET, we present the theoretical analysis related to p-MANET and also perform experimental simulations. The numerical results show that p-MANET reduces power consumption and routing latency and performs well in extending lifetime with a small neighbor discovery time. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Supported by the IEEE 802.15.4 standard, embedded sensor networks have become popular and been widely deployed in recent years. The IEEE 802.15.4 medium access control (MAC) protocol is uniquely designed to meet the desirable requirements of the low end-to-end delay, low packet loss, and low power consumption in the low rate wireless personal areas networks (LR-WPANs). This paper develops an analytical model to quantify the key performance metrics of the MAC protocol in LR-WPANs with bursty ON-OFF traffic. This study fills the gap in the literature by removing the assumptions of saturated traffic or nonbursty unsaturated traffic conditions, which are unable to capture the characteristics of bursty multimedia traffic in sensor networks. This analytical model can be used to derive the QoS performance metrics in terms of throughput and total delay. The accuracy of the model is verified through NS-2 (http://www.isi.edu/nsnam/ns/) simulation experiments. This model is adopted to investigate the performance of the MAC protocol in LR-WPANs under various traffic patterns, different loads, and various numbers of stations. Numerical results show that the traffic patterns and traffic burstiness have a significant impact on the delay performance of LR-WPANs. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Because the orthogonal frequency division multiple access physical resource available for scheduling in Worldwide Interoperability for Microwave Access networks is frame by frame, an uplink scheduler located at the base station must efficiently allocate available resources to the subscriber stations in response to constant or bursty data traffic on a per-frame basis. Available resources for real-time and nonreal-time traffics, called frame-based adaptive bandwidth allocation and minimum guarantee and weight-based bandwidth allocation, respectively, are proposed in this paper. Moreover, both short-term and long-term bandwidth predictions for traffic are incorporated so that the long-term bandwidth prediction can have sustainable throughput requirement, and the short-term bandwidth prediction can meet the objectives of low delay and jitter. For the scenarios studied, it shows that system performance of the proposed algorithm is better than the hybrid (earliest deadline first + weighted fair queuing + FIFO) algorithm in terms of packet delay, jitter, throughput, and fairness. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Carrier sense multiple access and its variants have been widely used in mobile ad hoc networks. However, most existing access mechanisms cannot guarantee quality of service for real-time traffic. In this paper, we present a novel approach to guarantee the performance of real-time applications such as voice and video that require periodic access to the wireless local area network (WLAN) channel. Our approach can work either with distributed coordination function or enhanced distributed coordination function, and includes distributed reservations of time slots between the stations sharing the WLAN without the need to send any signaling or control messages. Stations can access the wireless medium only if they are able to complete the frame transmission without interruption to the reserved slots of existing real-time sessions. Simulation results indicate that the proposed mechanism provides high channel utilization, and bounded delays and jitter for real-time traffic. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, an initial spectrum access control algorithm for cognitive wireless networks was studied. The objective was to maximize the number of admitted secondary users (SUs) under the constraints of interference temperature at multiple measurement points (MPs), while providing active SUs' QoS protection (AQP). Here, AQP means that the signal-to-interference-plus-noise ratios (SINRs) of all active SUs will not fluctuate below some predefined thresholds during a new SU's initial spectrum access process. To this end, we proposed a new distributive power control algorithm in conjunction with a simple alarm mechanism that ensures the interference temperatures at multiple MPs to be always below their thresholds during the initial spectrum access process. Then, two realizations of the spectrum access algorithms, namely, D-AQP and C-AQP, according to whether the MPs can act as local controllers or not, were presented. In the D-AQP algorithm, each SU updates its transmit power distributively based on the local information including the current SINR, the QoS requirement, and the indicator from the MPs so that the resultant SINRs of the active SUs are able to stay above the predefined thresholds. Whereas in the C-AQP algorithm, apart from the same procedure as mentioned, each MP is supposed to be able to decide which new SU should quit the initial spectrum access process so as to protect the communication quality of the primary system. Finally, the performances of the proposed algorithms were validated by extensive simulations. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Optical burst switching (OBS), which takes advantage of both high capacity of optical fiber and sophisticated control of electronics, has been considered as a promising paradigm for the modern Internet. In this paper, the recovery procedures for IP over OBS/WDM multilayer network are addressed, which focus on the failure detection and failure localization. Bidirectional forwarding detection (BFD) mechanism which provides low-overhead, short-duration detection of failures in the path between adjacent forwarding engines, including the interfaces, data link(s) is introduced for the failure detection and localization in the IP over OBS/WDM multilayer network, especially at the OBS/WDM layer. The unique feature of OBS and the easy-to-implement merit of BFD make it feasible for BFD adopted at OBS/WDM layer. Besides, BFD is a highly cost effective method when compared with traditional methods such as detecting the Loss of Light of each wavelength. Not only the implementation details of BFD-based failure detection for the OBS/WDM layer are demonstrated in this paper, but also how the BFD localizes failures such as fiber failure, link failure and node failure. Moreover, extensive simulations have been done at different scenarios such as single failure and multiple failures. And the numerical results concerning the performance of BFD-based failure detection and localization in terms of failure detection and localization time and BDP lost rate verified the proposed solution. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Net neutrality (NN) is a widely debated policy issue that has the potential to alter the dynamics of accessing online content. The focal point of the debate lies in whether broadband service providers (BSPs) should be allowed to charge content providers for the preferential delivery of their digital content. This decision will affect broadband market coverage for end consumers as well as the issues of long-term competition and innovation in the market of digital content. Our research aims to analyze and address these issues. We propose a game theoretical model with three players-the BSP, the content providers, and the consumers-where the BSP, in its capacity as a gatekeeper between the content providers and the consumers, is modeled as a two-sided market platform. We find that while abandoning the principle of NN might sometimes result in increased consumer surplus and broadband market coverage, it can also hinder the ability of startups to compete against established rivals and thus reduce innovation at the edge. The results should be of great interest to policymakers as they debate on this very crucial issue. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate a service-aware optical transport system. The proposed service-aware optical transport system makes a flow based on service type and priority of traffic. The generated flow is mapped to a corresponding sub-? for transport over an optical network. Using sub-λ provided by the centralized control plane, we could effectively provide quality-ofservice guaranteed Ethernet service and best-effort service simultaneously in a single link. The committed information rate (CIR) traffic and best-effort traffic are assigned to different sub-λs. The bandwidth of the CIR traffic is guaranteed without being affected by violation traffic because the bandwidth is managed per each sub-λ. The failure detection time and restoration time from a link failure is measured to be about 60 μs and 22 ms, respectively, in the ring network. The measured restoration time is much smaller than the 50 ms industry requirement for real-time services. The fast restoration time allows the proposed service-aware optical transport system to offer high availability and reliability which is a requirement for transport networks. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. [ABSTRACT FROM AUTHOR]

Summary: In the network neutrality debate, safeguarding innovations in the digital economy is an important concern. However, the impacts of network neutrality regulation on technological innovation in telecommunications have not been well understood, especially with mathematical model. This study first briefly discusses the significant role of technological innovation in telecommunications. Then, we adopt a stylized two‐sided model (Internet broadband provider connect the two sides of Internet, content providers and end customers) and use two‐stage game theory to examine the decision‐making of network operators and content providers in two alternative situations, respectively, that is, the neutral regime and non‐neutral regime. By comparing players' decisions in the two regimes, the impacts of network neutrality regulation on innovations are revealed. We find that non‐neutral regime increases both network infrastructure investments and congestion‐sensitive content innovations. In other words, network neutrality regulation inhibits telecommunications technological innovation and meanwhile hinders the emergence of high‐level content innovation. [ABSTRACT FROM AUTHOR]

Current rapid increasing implementations in data diversity, autonomy, and dynamic privilege management, fine-grained access controls in social networks have resulted in various challenges in applying existing access control models. The intercrossing relations lead to the complex access control system, which often brings risks when the system is updated or expanded. The implementations of cloud computing has further complicate the access controls due to multiple tenancies and service providers. We focus on this issue and propose a new social network access control model using logical authorization language, named as RuleSN, which can be efficiently used in cloud systems. This model provides high performance of authorization expressiveness and flexibility that can effectively describe relations of User to User (U2U), User to Resource (U2R), Resource to Resource (R2R) and attributes of users and resources. First, this paper elaborates the formal definitions of the RuleSN model. Second, we describe the model's authorization specification and verification policies and explain the syntax and semantics of the authorization language. Finally, the implementation, application, and expressiveness of the model discussed by examples. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article reports on the new social entrepreneurship initiative by South African digital agency Krazyboyz Digital. It is stated that internet access, hosting, and website development is prohibitively expensive in South Africa effectively shutting the internet door on start-up companies. Due to the new project by the Krazyboyz Digital, young South African entrepreneurs are being given a helping hand onto the information superhighway. It is also said that a partnership between Umsobomvu youth Fund and Krazyboyz would allow SMIs to set up their own business websites.