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Most existing network communication systems, such as the Internet, are built around the TCP/IP protocol stack. However, TCP/IP cannot effectively support the upcoming network communication systems with more wireless communication links and higher requirements in terms of throughput, latency, and reliability. In this article, we introduce a general network communication protocol design based on batched network coding (BNC), which includes the existing framework as a special case and whose design can be guided by channel coding theory. BNC-based protocols can have significant throughput gain for single-hop or multihop wireless communications and provide better trade-off among throughput, latency and reliability. [ABSTRACT FROM AUTHOR]

Satisfying the stringent 5G quality of service requirements necessitates efficient resource utilization by mobile networks. Consequently, we argue that multi-connectivity (MC) is an effective solution to leverage the limited radio resources from multiple base stations in order to enhance user throughput, provide seamless connectivity, and increase data reliability. For this, we study different MC architectures, where distinct network entities and protocol layers are used to split or aggregate the user traffic. The benefits and challenges of MC are analyzed as well as the open issues that network/device vendors and mobile network operators have to address for its use. Finally, through experimental evaluations, we illustrate the importance of MC design decisions for overall network performance. [ABSTRACT FROM AUTHOR]

Real-world robot networks create hostile radio environments due to their highly dynamic communication topologies and stringent real-time transmission requirements. In this article, we propose improvements to contention-based networks that utilize inter-robot navigation information for safer robot motion control in dense multi-robot settings. Toward this end, we introduce a Crash Risk Prioritization (CRP) index, which is employed as the core metric in a scheme of dynamic beacon rate control. Key to our approach is a coupled evaluation setup that allows us to evaluate the impact of network-level changes on the safety of robot navigation. Our results demonstrate that the co-design and simulation of robotic control algorithms and network protocols provide key insights and metrics into the network-level requirements for V2V systems. These insights allow us to make informed conclusions about how such networks can be best served by emerging standards. [ABSTRACT FROM AUTHOR]

IoT has evolved from an experimental to a backbone technology able to connect myriads of people, things, and services for a large range of businesses. At the same time, the emergence of SDN can ideally handle IoT challenges for elasticity, heterogeneity, and mobility, offering an architecture that abstracts decision making away from the data plane and providing a programmable network facility. Along these lines, we propose MINOS, a multi-protocol SDN platform for IoT that implements service awareness utilizing appropriate SDN abstractions and interfaces for logically centralized network control of diverse and resource-constrained IoT environments, two network protocols that are deployable and configurable on demand, and a GUI that provides a bespoke dashboard and a real-time visualization tool. Due to its components, MINOS enables experimentation with novel network control features and protocols that realize optimized routing over heterogeneous IoT nodes, application of real-time strategies as a response to dynamic network conditions, support of individual protocol configurations per node, and flexibility to accommodate new protocols and control algorithms. Our results demonstrate MINOS as an enabling platform for two protocols, CORAL-SDN and Adaptable-RPL, which, in comparison with the state-of-the-art IoT routing protocol RPL, improve the packet delivery ratio with relatively small control overhead. [ABSTRACT FROM AUTHOR]

Extending an Internet subnet by connecting resource-constrained nodes (e.g., embedded sensors and actuators) over multiple wireless hops is necessary to support the future Internet of Things (IoT). RPL, the IPv6 routing standard for low-power and lossy networks, tried to achieve this goal but has not seen wide adoption in practice. As an alternative, Thread is a recently standardized low-power network protocol for IoT, driven by the Thread group, an industry consortium led by Google/Nest. We provide a comparative analysis of the technical aspects of RPL and Thread based on their specifications, explaining why using Thread, as opposed to RPL, may make sense for the future Internet. Specifically, the fundamental differences between RPL and Thread are their respective scopes and multihop network architectures, which result in Thread's unique design and advantages over RPL. Lastly, we evaluate Thread in an indoor multihop wireless testbed using OpenThread, an official open source implementation of Thread. This work serves as the first analysis of the Thread protocol in academia. [ABSTRACT FROM AUTHOR]

We describe a new vision of joint computation and communication resource management that goes beyond the end-to-end and client-server model of the current Internet. Enabled by a growing trend toward embedding processing and networking capabilities into "smart" network nodes and devices, for example, smartphones, watches, appliances, and automobiles, Dispersed Computing describes a new resource-centric architecture that leverages the diversity of networked computation points within the network, and the heterogeneity of network links and protocol stacks that connect them. We describe this new, resource-centric architecture as an evolution of both fog/edge networking and active networks. We illustrate the fundamental principles and the advantages over the current Internet architecture, and highlight several commercial use cases enabled by a dispersed computing architecture. [ABSTRACT FROM AUTHOR]

Wind energy is one of the most attractive and one of the fastest growing sources of green energy in the world. With the expansion of wind parks, there is a growing need for an efficient coordination of the diverse energy production systems, as well as a tighter coupling between the production and the consumer side of the grid. Current grid operators have unnecessarily high costs due to the lack of an integrated management system toward a diverse set of proprietary network protocols, complex and error prone operation of the networks, as well as rigid security mechanisms. Network softwarization concepts, that is, SDN and NFV, offer great potential for reducing capital and operational expenditures by providing simplified network management and automated control. Recent works have demonstrated the feasibility of achieving stringent industrial-grade quality of service and fine grain security control with SDN and NFV. In this article, we provide an insight into wind park communication network requirements, analyze the technological benefits of the network softwarization, and demonstrate the economic profits in a case study of a typical Northwestern Europe wind park. [ABSTRACT FROM AUTHOR]

Network latency and reliability are becoming critical performance indicators for future mission critical services based on wireless connectivity. In this article we present a portable and low-cost measurement framework for quantifying the endto- end (E2E) latency and reliability of communication systems based on single or multiple links. The proposed framework is tailored for characterization of access diversity mechanisms, for example, multi-connectivity or hybrid access methods, which are expected to be essential for ultra-reliable wireless communications in 4G and 5G networks. An active-probe measurement approach is adopted, consisting of a client that transmits timestamped packets to a server, and vice versa, via one or multiple communication links under test. The setup allows us to measure the one-way latency performance in uplink and downlink separately, and allows fully synchronized measurements of multiple links in parallel to understand the benefits of multi-connectivity mechanisms. Traffic generation is flexible in terms of packet size, transport protocol (TCP or UDP), and inter-arrival time interval of the generated packets, hence being a powerful tool for benchmarking the performance for different application-specific message flows. Special emphasis is put on the tail of the latency distribution, that is, the latency that can be achieved with a certain probability constraint, for example, 99.9 percent or beyond. Given the challenge of measuring such rare events, we measure and validate the stability of the measurement equipment to ensure that the observed performance is not compromised by undesired behavior or malfunction of the equipment. The system has a measurement error below 400 μs with 99.9 percent confidence and below 3.1 ms with 99.999 percent confidence. The capability and applicability of the measurement framework is illustrated by a measurement test of two simultaneous LTE connections that provide robust communications to an aerial drone. [ABSTRACT FROM AUTHOR]

The world of connected devices has led to the rise of the Internet of Things paradigm, where applications rely on multiple devices, gathering and sharing data across highly heterogeneous networks. The variety of possible mechanisms, protocols, and hardware has become a hindrance in the development of architectures capable of addressing the most common IoT use cases, while abstracting services from the underlying communication subsystem. Moreover, the world is moving toward new strict requirements in terms of timeliness and low latency in combination with ultra-high availability and reliability. Thus, future IoT architectures will also have to support the requirements of these cyber-physical applications. In this regard, edge computing has been presented as one of the most promising solutions, relying on the cooperation of nodes by moving services directly to end devices and caching information locally. Therefore, in this article, we propose a modular and scalable architecture based on lightweight virtualization. The provided modularity, combined with the orchestration supplied by Docker, simplifies management and enables distributed deployments, creating a highly dynamic system. Moreover, characteristics such as fault tolerance and system availability are achieved by distributing the application logic across different layers, where failures of devices and micro-services can be masked by this natively redundant architecture, with minimal impact on the overall system performance. Experimental results have validated the implementation of the proposed architecture for on-demand services deployment across different architecture layers. [ABSTRACT FROM AUTHOR]

As multimedia services are gaining considerable popularity in the Internet of Things, providing QoE in smart mmIoT becomes a challenging issue. This article conceptualizes a new framework named SMP, to price the QoE rather than the binary data traffic in IoT multimedia services. By introducing PaaR in QoE-driven network scheduling in mmIoTs, a new dimension of price distortion is available in multimedia resource allocation, complementing traditional rate distortion and power distortion resource allocation approaches. This article also discusses open research challenges in SMP resource allocation, including the difficulty of numerical presentation of QoE, the unavailability of packet-level distortion information, and the non-concavity of the utility functions. A case study is presented to illustrate the PaaR potentials of improving QoE through the SMP framework in mmIoTs. [ABSTRACT FROM AUTHOR]

Pervasively implemented IoT systems are introducing unprecedented threats to our society. In this article, aiming to explore the security impact from the emerging and anarchistic IoT systems, we survey the state of the art of the security and privacy issues in the smart IoT world from a networking perspective. We predict that IoT systems will be extensively used by hackers to commit malicious actions given the features of IoT devices and systems. We also discuss the privacy issue caused by IoT systems. Finally, we present our understanding of counterattacks from both the application and theoretical aspects. We hope this article will shed light on the research field for interested readers. [ABSTRACT FROM AUTHOR]

Network slicing is a fundamental capability for future Fifth Generation (5G) networks to facilitate the cost-effective deployment and operation of multiple logical networks over a common physical network infrastructure in a way that each logical network (i.e. network slice) can be customized and dimensioned to best serve the needs of specific applications (e.g. mobile broadband, smart city, connected car, public safety, fixed wireless access) and users (e.g. general public, enterprise customers, virtual operators, content providers). The practical realization of such capability still raises numerous technical challenges, both in the Core and RAN parts of the 5G system. Through a comprehensive analysis of the impact that the realization of RAN slicing has on the different layers of the radio interface protocol architecture, this article proposes a framework for the support and specification of RAN slices based on the definition of a set of configuration descriptors that characterize the features, policies and resources to be put in place across the radio protocol layers of a next-generation RAN node. [ABSTRACT FROM PUBLISHER]

The Internet of Things has been widely deployed in various areas of daily life through heterogeneous communications protocols. Each unstandardized protocol focuses on a specific IoT communication pattern. Inspired by the Internet architecture over which divergent devices can easily be accessed and a considerable number of applications can be run, we propose a generic architecture for IoT. This architecture supports two DIY areas: network DIY for data aggregation and application DIY for service cooperation. To connect these two DIYs, a centralized controller has been designed to provide standardized interfaces for data acquisition, organization, and storage, and to support elastic and supportive computing. With these properties, divergent devices can coexist in a uniform microworld, and rich services can be developed and provided on demand to interoperate with physical devices. This article discusses the background, design principles, and advantages of the proposed architecture, as well as open problems and our initial solution, which substantiates a novel IoT architecture and new research ground. [ABSTRACT FROM PUBLISHER]

Wireless customers expect to have a guaranteed quality of experience at all times, at any location, and through different devices. Wi-Fi has become an access network of preference for service/ network providers and customers as well for public and private access. This sets a challenging requirement for next-generation Wi-Fi technology to provide seamless and uniform network quality of service). Consequently, the necessity for self-optimization of network and radio frequency segments becomes critical. This article surveys challenges and use cases of Wi-Fi self-optimizing networks (Wi-SONs) that have not been presented to date. We address technology and design challenges that shape Wi-SON as a very complex problem. [ABSTRACT FROM PUBLISHER]

Toward ITS, academia and industry aim to utilize all possible radio access technologies in order to support reliable services and applications in VANETs. Thus, the inclusion of already deployed Wi-Fi networks in VANET topology is a crucial step for the next generation vehicular networks. However, the VANET topology also requires preservation of the features already offered by DSRC and the core cellular network. As a result, the coexistence of multiple different access technologies results in high complexity in terms of the control and management of the network infrastructure. To this end, software defined networking provides a promising opportunity to simplify the management and control of clumsy network infrastructures by decoupling the data and control planes in order to provide elasticity for current networks. In this article, we propose an architectural model that exploits this opportunity in order to enhance VANET with Wi-Fi access capability. Moreover, we offer a novel software defined VANET architecture that consists of soft OpenFlow switches with Wi-Fi capabilities as both roadside units and vehicles. In particular, we first investigate existing test tools and environments for software defined wireless networks and also supply a novel testbed architecture in order to provide a feasible test environment for evaluating the proposed architecture. Additionally, we propose a Wireless Access Management (WAM) protocol that provides wireless host management and basic flow admission with respect to the available bandwidth to validate the capability of the offered architecture. The observation results of the deployed testbed prove the conformity of the offered 802.11 architecture to the VANET. [ABSTRACT FROM PUBLISHER]

Underwater sensor networks have enabled a new era in scientific and industrial underwater monitoring and exploration applications. However, these networks are energy-constrained and, more problematically, energy-hungry, as a consequence of the use of underwater acoustic links. In this work, we thoroughly review potential techniques for greening underwater sensor networks. In a top-down approach, we discuss the principal design and challenges of the appealing highlighted techniques. We also exemplify their use by surveying recent proposals in underwater sensor networks. Finally, we describe potential future research directions for energy conservation in underwater networks. [ABSTRACT FROM PUBLISHER]

Many people, especially technology historians, often ponder "Where would the world be without Ethernet?" Now, such a rhetorical question typically has no answer because you cannot rewind time, remove Ethernet from being invented, and let time fast forward to the present day. However, we have many active contributors amongst us who have been part of that history as it has evolved over the past 30 years. The Evolution of Ethernet Standards in 802.3 Working Group covers great details on the history of not just Ethernet standards development, but many dot standards that have led to support of wide-ranging applications. For me, just the first sentence captures the past, the present, and the future that I'd like to know more about: Ethernet is constantly evolving, adapting to the needs of the networking world, addressing the requirements of both operators and end-users, while making sure that the resulting technology is cost-efficient, reliable, and operates in a plug and play manner. [ABSTRACT FROM AUTHOR]

SDN is a centrally managed network architecture that automatically and dynamically allocates network resources to different types of workloads according to their application characteristics as well as current network conditions. We note that state-of-the-art SDN measurement mechanisms generally are slow, require reserved network resources, or use protocol-specific information when collecting flow-level statistics and constructing global network views. The lack of a fast and accurate SDN measurement mechanism significantly limits the effectiveness of SDN. In this article, we focus on the design of a scalable, accurate, and fast SDN measurement mechanism. We exploit packet-level statistics and propose a low-latency load-aware two-tier measurement and control platform for SDN. The port counter of the SDN switch, which tracks the number of bytes and packets that are sent and received on each port, is used for estimating link utilizations. The SDN switch actively monitors link states and pushes the statistics back to the SDN controller periodically for the detection of network congestion. When necessary, the controller can retrieve the flow statistics of the congested link from the SDN switches for traffic engineering. We implement a small-scale testbed and conduct emulations for evaluation. The experiment results show that compared to OpenSample and Planck, our two-tier mechanism quickly and accurately estimates link utilization and controls flow routes for better bisection throughput. [ABSTRACT FROM AUTHOR]

The article presents the discussion on meaning or semantics of the data. Topics include advancements in artificial intelligence (AI) providing a powerful tool for solving fundamental problems in semantic communications; and semantic communications in emerging wireless networks such as virtual reality and autonomous driving.

Single Sign On (SSO) protocols are today integrated in millions of web services so end users can authenticate to a third-party identity provider (IdP) to access multiple services. IdPs normally provide integration tools that hide almost all implementation details and allow developers to implement SSO in minutes. Such integration tools along with cumbersome protocol specifications result in developers without a clear view of the underlying SSO protocol. This article presents a conceptual characterization of web SSO protocols through their assertions and their features that help preserve the privacy of the user resources involved in SSO. [ABSTRACT FROM PUBLISHER]

CoAP is a lightweight RESTful application layer protocol devised for the IoT. Operating on top of UDP, CoAP must handle congestion control by itself. The core CoAP specification defines a basic congestion control mechanism, but it is not capable of adapting to network conditions. However, IoT scenarios exhibit significant resource constraints, which pose new challenges on the design of congestion control mechanisms. In this article we present CoCoA, an advanced congestion control mechanism for CoAP being standardized by the Internet Engineering Task Force CoRE working group. CoCoA introduces a novel round-trip time estimation technique, together with a variable backoff factor and aging mechanisms in order to provide dynamic and controlled retransmission timeout adaptation suitable for the peculiarities of IoT communications. We conduct a comparative performance analysis of CoCoA and a variety of alternative algorithms including state-of-the-art mechanisms developed for TCP. The study is based on experiments carried out in real testbeds. Results show that, in contrast to the alternative methods considered, CoCoA consistently outperforms the default CoAP congestion control mechanism in all evaluated scenarios. [ABSTRACT FROM PUBLISHER]

Buffer sizing is an important network configuration parameter that impacts the quality of service characteristics of data traffic. With falling memory costs and the fallacy that "more is better," network devices are being overprovisioned with large buffers. This may increase queueing delays experienced by a packet and subsequently impact stability of core protocols such as TCP. The problem has been studied extensively for wired networks. However, there is little work addressing the unique challenges of wireless environments such as time-varying channel capacity, variable packet inter-service time, and packet aggregation, among others. In this article we discuss these challenges, classify the current state-of-the-art solutions, discuss their limitations, and provide directions for future research in the area. [ABSTRACT FROM PUBLISHER]

Autonomous driving technology has been regarded as a promising solution to reduce road accidents and traffic congestion, as well as to optimize the usage of fuel and lane. Reliable and highly efficient vehicle-to-vehicle and vehicle-to-infrastructure communications are essential for commercial autonomous driving vehicles to be on the road before 2020. The current article first presents the concept of heterogeneous vehicular networks (HetVNETs) for autonomous driving, in which an improved protocol stack is proposed to satisfy the communication requirements of not only safety but also non-safety services. We then consider and study in detail several typical scenarios for autonomous driving. In order to tackle the potential challenges raised by the autonomous driving vehicles in HetVNETs, new techniques from transmission to networking are proposed as potential solutions. [ABSTRACT FROM AUTHOR]

Nowadays, the explosively growing demands for mobile service bring both challenges and opportunities to wireless networks, giving birth to fifth generation (5G) mobile networks. The features and requirements of different services are diverse in 5G. The management and coordination among heterogeneous networks, applications, and user demands need the 5G network to be open and flexible to ensure that network resources are allocated with high efficiency. To fulfill these requirements, wireless network virtualization is used to integrate heterogeneous wireless networks and coordinate network resources. In this article we propose a model of wireless network virtualization consisting of three planes: the data plane, the cognitive plane, and the control plane. A novel control signaling scheme has also been designed to support the proposed model. From the implementation perspective of network virtualization, a hierarchical control scheme based on cell-clustering has been used with dynamically optimized efficiency of resource utilization. Two use cases have been analyzed to demonstrate how the schemes work under the proposed model to improve resource efficiency and the user experience. [ABSTRACT FROM AUTHOR]

With trillions of machines connecting to mobile communication networks to provide a wide variety of applications, supporting a massive number of machine-to-machine (M2M) communications devices has been considered an essential requirement for mobile operators. Meanwhile, cyber security is of paramount importance in M2M as all applications involving M2M cannot be widely accepted without security guarantees. In this article we focus on the standardization activities of 3GPP, especially group-based security for largescale M2M communications in 3GPP networks. We first introduce the main components of the machine-type communication (MTC) security architecture. Then we discuss several major challenges for group-oriented secure M2M communications in 3GPP systems, i.e. authentication signalling congestion and overload, and group message protection. Specifically, we identify the performance issues of authentication signalling congestion and overload in no/low mobility scenarios, and propose three group access authentication and key agreement protocols. Moreover, several 3GPP candidate solutions for group message protection are introduced. Finally, we present key issues and research directions related to group-based secure M2M communications, including security, privacy, and efficiency in mobility scenarios of MTC, and flexible and efficient group key management. [ABSTRACT FROM AUTHOR]

Vehicular communications are emerging as a promising technology to enable communications using vehicles as network nodes. VDTNs appear as a novel approach to enable services and applications where it is not possible to define an end-to-end path. To allow communications in such challenging environments, VDTNs rely for their operation on cooperation between network nodes, which contributes to increasing network connectivity and improving overall network performance. To accomplish such a task, nodes may be asked to share their constrained storage, bandwidth, and energy resources with one another. However, nodes may be unwilling to cooperate in order to save resources or due to selfish behavior. This kind of node severely affects the network functionality. This article gives an overview of the field, providing motivations, challenges, and an evaluation of the impact of cooperative measures on the performance of VDTN networks. [ABSTRACT FROM AUTHOR]

With ever growing mobile Internet and the explosion of its applications, users are experiencing abundant services from different content providers via different network service providers in the heterogeneous network. The information-centric network (ICN) advocates getting rid of the current host-centric network protocol because information dissemination rather than end-to-end communication contributes to the majority of today's network traffic. Furthermore, it is better for network entities to converge as a whole in order to take advantage of open, scalable, and smart traffic transmission. The cloud radio access network is one of the emerging architecture evolutions on the wireless side for easier infrastructure deployment and network management. Therefore, when the information-centric network meets the C-RAN in the Het-Net, it is worthwhile and consequential to integrate ICN protocol with C-RAN architecture to achieve more efficient communication and information management. Moreover, SDN has been recognized as another promising architecture evolution to achieve the flexibility and reconfigurability of dense HetNets; its inherent advantage lies in global uniform control of the wired network. Thus, any of ICN, C-RAN and SDN is the complementary to the others. In this article, we contribute to a fresh proposal for and elaboration of the integration of the ICN, CRAN, and SDN for the HetNet to achieve a win-win situation. The vision of the proposed system is demonstrated, followed by the advantages and challenges. We further present a hybrid system in a large-scale wireless heterogeneous campus network. [ABSTRACT FROM PUBLISHER]

Knowledge of end-to-end network distances is essential to many service-oriented applications such as distributed content delivery and overlay network multicast, in which the clients have the flexibility to select their servers from among a set of available ones based on network distance. However, due to the high cost of global measurements in large-scale networks, it is infeasible to actively probe end-to-end network distances for all pairs. In order to address this issue, network distance prediction has been proposed by measuring a few pairs and then predicting the other ones without direct measurements, or splicing the path segments between each pair via observation. It is considered important to improve network performance, and enables service- oriented applications over large-scale networks. In this article, we first illustrate the basic ideas behind network distance prediction, and then categorize the current research work based on different criteria. We illustrate how different protocols work, and discuss their merits and drawbacks. Finally, we summarize our findings, and point out potential issues and future directions for further research. [ABSTRACT FROM PUBLISHER]

Information-centric networking (ICN) is an emerging networking paradigm that places content identifiers rather than host identifiers at the core of the mechanisms and protocols used to deliver content to end users. Such a paradigm allows routers enhanced with content-awareness to play a direct role in the routing and resolution of content requests from users, without any knowledge of the specific locations of hosted content. However, to facilitate good network traffic engineering and satisfactory user QoS, content routers need to exchange advanced network knowledge to assist them with their resolution decisions. In order to maintain the location-independency tenet of ICNs, such knowledge (known as context information) needs to be independent of the locations of servers. To this end, we propose CAINE — Context-Aware Information-centric Network Ecosystem — which enables context-based operations to be intrinsically supported by the underlying ICN routing and resolution functions. Our approach has been designed to maintain the location-independence philosophy of ICNs by associating context information directly to content rather than to the physical entities such as servers and network elements in the content ecosystem, while ensuring scalability. Through simulation, we show that based on such location-independent context information, CAINE is able to facilitate traffic engineering in the network, while not posing a significant control signalling burden on the network. [ABSTRACT FROM PUBLISHER]

The article reports that In contrast to the Shannon paradigm whose underlying principle is to guarantee the correct reception of each single transmitted packet regardless of its meaning, semantic communication is concerned with the problem of how transmitted symbols convey a desired meaning to the destination, as well as how effectively the received meaning affects the action in a desired way.

The article reports that During the last two years of COVID-19 pandemic the importance of e-work and remote collaboration systems as key contributors to the technological and economic progress of many industries has become more and more clear. Countries and companies that were able to rapidly adapt to the changes in work settings and dynamics brought about by the pandemic were able to significantly limit the economic impact of the pandemic in those fields that don't require physical presence.

The rise of machine-to-machine communications has rekindled interest in random access protocols as a support for a massive number of uncoordinatedly transmitting devices. The legacy ALOHA approach is developed under a collision model, where slots containing collided packets are considered as waste. However, if the common receiver (e.g. base station) is able to store the collision slots and use them in a transmission recovery process based on successive interference cancellation, the design space for access protocols is radically expanded. We present the paradigm of coded random access, in which the structure of the access protocol can be mapped to a structure of an erasure-correcting code defined on a graph. This opens the possibility to use coding theory and tools for designing efficient random access protocols, offering markedly better performance than ALOHA. Several instances of coded random access protocols are described, as well as a case study on how to upgrade a legacy ALOHA system using the ideas of coded random access. [ABSTRACT FROM PUBLISHER]

Cellular networks are confronted with unprecedented pressure to accommodate the dramatically increasing demands of mobile Internet. This phenomenon is principally due to the restricted spectrum resource and low-efficiency spectrum management. Recently, cognitive radio technology has been corroborated to significantly improve spectrum utilization efficiency. In order to enhance the spectrum management efficiency in cellular networks, the concept of ?cognitive cellular networks? was introduced. It has been realized that the network architecture, algorithms, and protocols cannot be simply designed without considering the socio-economic aspects involved. In this article, we consider the economic issues in cognitive cellular networks from the perspectives of game theoretic modeling and mechanism design. Specifically, both the simultaneous and sequential dynamic spectrum access games are investigated, respectively. The mechanism design related issues (i.e., spectrum auction, pricing, and contract) to ensure desired outcomes are introduced with detailed applications in cognitive cellular networks. The goal of this article is to provide an overview to understand the motivation, problem formulation, methodology, and solutions of the economic issues in cognitive cellular networks. [ABSTRACT FROM PUBLISHER]

The fifth generation (5G) network will serve as a key enabler in meeting the continuously increasing demands for future wireless applications, including an ultra-high data rate, an ultrawide radio coverage, an ultra-large number of devices, and an ultra-low latency. This article examines security, a pivotal issue in the 5G network where wireless transmissions are inherently vulnerable to security breaches. Specifically, we focus on physical layer security, which safeguards data confidentiality by exploiting the intrinsic randomness of the communications medium and reaping the benefits offered by the disruptive technologies to 5G. Among various technologies, the three most promising ones are discussed: heterogenous networks, massive multiple-input multiple-output, and millimeter wave. On the basis of the key principles of each technology, we identify the rich opportunities and the outstanding challenges that security designers must tackle. Such an identification is expected to decisively advance the understanding of future physical layer security. [ABSTRACT FROM PUBLISHER]

Delay-tolerant networks, DTNs, are characterized by lacking end-to-end paths between communication sources and destinations. A variety of routing schemes have been proposed to provide communication services in DTNs, and credible and flexible protocol evaluation tools are in demand in order to test these DTN routing schemes. By examining the evolution of DTN protocol testing and evaluation, this article discusses the trend toward large-scale mobility trace supported emulation, and we propose TUNIE, a large-scale emulation testbed for DTN protocol evaluation based on network virtualization. Unlike the existing simulation tools and real-life testbeds, which either cannot provide a realistic DTN environment setup or are too costly and time-consuming, our proposed TUNIE architecture is capable of simulating reliable DTN environments and obtaining an accurate system performance evaluation. By system prototype and implementation, we demonstrate TUNIE as a flexible platform for evaluating DTN protocol performance. [ABSTRACT FROM PUBLISHER]

Wireless sensor networks with mobile sinks, mWSNs, have attracted a lot of attention recently. This is because sink mobility can greatly alleviate the hotspot issue in WSNs and further prolong the network lifetime. However, sink mobility also causes unexpected changes in network topology and data routing paths, which can largely affect the routing performance in such networks. Design of efficient routing protocols for mWSNs has been a critical issue, and much work has been carried out in this aspect. In this article, we first classify existing protocols based on different design criteria and then present a survey of the state-of-the-art routing protocols in this area. We illustrate how each of the protocols works, and discuss their advantages and disadvantages. Finally, we point out some future directions for efficient routing in mWSNs. [ABSTRACT FROM AUTHOR]

Network management is achieved through a large number of disparate solutions for different technologies and parts of the end-to-end network. Gaining an overall view, and especially predicting the impact on a service user, is difficult. Recently, a number of proprietary platforms have emerged to conduct end-to-end testing from user premises; however, these are limited in scale, interoperability, and the ability to compare like-for-like results. In this article we show that these platforms share similar architectures and can benefit from the standardization of key interfaces, test definitions, information model, and protocols. We take the SamKnows platform as a use case and propose an evolution from its current proprietary protocols to standardized protocols and tests. In particular, we propose to use extensions of the IETF?s IPFIX and NETCONF/YANG in the platform. Standardization will allow measurement capabilities to be included on many more network elements and user devices, providing a much more comprehensive view of user experience and enabling problems and performance bottlenecks to be identified and addressed. [ABSTRACT FROM PUBLISHER]

This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied. [ABSTRACT FROM PUBLISHER]

Cooperative communication can increase the throughput and/or extend the coverage of wireless networks. However, in conventional cooperative networks, half-duplex relays transmit and receive under a prefixed schedule, which does not allow them to exploit the best receiving and transmitting channels, thus limiting performance. Recently, new protocols have been proposed that circumvent this problem by making use of the additional flexibility offered by relays with buffers. Compared to conventional relaying protocols, these buffer-aided protocols provide significant gains in terms of throughput, diversity, and signal-to-noise ratio. This article outlines several buffer-aided relaying protocols for different network topologies, including one-way single- and multi-relay networks as well as two-way single-relay networks. Moreover, some practical challenges inherent to buffer-aided relaying, such as increased delay and complexity, and topics for future research are discussed. [ABSTRACT FROM PUBLISHER]

Testing networking devices before releasing them onto the market is a way of ensuring quality and robustness. Replaying artificial or realworld traffic is a method to test networking devices. Using real-world traffic is desirable as it uncovers more realistic properties. The challenges of testing with real-world traffic are mainly the high volume of the captured traces and the prolonged time required for replay testing. In order to efficiently reproduce the failures of networking devices and reduce the replay time, it is necessary to reduce the size of the traces that have triggered the failures. In this work, two algorithms used to downsize the traces but still retain the failures they triggered, Binary Downsizing (BD) and Linear Downsizing (LD), are proposed. Meanwhile, a metric called downsizing ratio (DR), the ratio between the size of the downsized traces and that of the original traces, is defined in order to evaluate the efficiency of the trace downsizing. Three kinds of probes following the basic RFC benchmarking requirements, ARP, ICMP, and HTTP requests, are regularly sent to diagnose the devices during the testing. ARP and ICMP probes test the reachability of a networking device hosted on the local network, and HTTP probes check if the device still responds to users? requests. The evaluation of failure distribution shows that 70 percent of failures happened because they failed to respond to one of the three probes, 23 percent failed to respond to two probes, and 7 percent failed to respond to all probes. From the downsizing experiments, LD was inferred to have a slightly higher DR than that of BD, but BD generally would require fewer iterations than LD. [ABSTRACT FROM PUBLISHER]

This article considers the concept of device-to- device communications for the resolution of persistent issues in mobile networks. Specifically, two scenarios are described, the opportunistic coverage expansion of the infrastructure, where an access point transits to offline mode (and hence its terminals shall exploit the presence of neighboring devices in order to reroute their traffic to alternative APs), as well as the opportunistic capacity expansion scenario where an AP faces congestion issues due to the excessive traffic of its terminals or the use of an obsolete RAT with low capacity. In the same manner, part of the traffic shall be offloaded to alternative APs through the creation of D2D links with neighboring devices. In order to realize the proposed solutions, the network elements exchange information regarding their capabilities and their status so as to identify the best path from all the potential ones. Therefore, control channels for cognitive radio systems will be utilized since the information that is conveyed through them comprises information from all the layers of the protocol stack. Furthermore, the article focuses on the coverage expansion scenario, which is implemented at the w.iLab-t testbed. In order to realize the D2D constructs, the devices of the testbed will be configured to communicate through WiFi technology, and specifically the 802.11s standard for wireless mesh networks, in order to enable multihop communications. In this respect, the D2D constructs that will be created are mesh networks that comprise the problematic terminals, their neighboring terminals that offload their traffic, and the APs that receive the traffic. In order to evaluate the proposed solution, the signaling loads of the conveyed messages are measured, as well as the performance of the mesh network that is created after the solution enforcement through the use of a ping, a file transfer, and a video streaming application. [ABSTRACT FROM PUBLISHER]

We present the Direct Code Execution (DCE) environment for ns-3, notable for being the first free open source framework for integrating Linux kernel and application code within a leading discrete-event network simulator. This new approach has many potential advantages over virtual-machine-based frameworks in terms of realism, reproducibility, avoidance of realtime execution constraints, configuration management, and the ability to debug a network-wide experiment from a single address space using common debugging tools. We provide an overview of DCE and illustrate some key features of this framework with two use cases, one involving thttpd, an HTTP server implementation, and another one involving the udp-perf traffic generator. [ABSTRACT FROM PUBLISHER]

Smart homes and environments will consist of a large number of low power wireless devices such as sensors and actuators. Recently IETF standardized a network protocol called RPL that is designed to run on these nodes. In this article, we study the performance of RPL on a variety of scenarios that these nodes will encounter when they are deployed in practice. We deploy a network of 23 sensor nodes in a computer lab to monitor energy used by each computer across the applications and users. We subject the network to four different levels of interference that are representative of the types and levels of interference that these networks might encounter in deployment. Our study finds that RPL?s reliability degrades even with an access point in overlapping channel under normal network traffic. With high interference, the packet delivery reliability goes down to 10 percent. The scenario that resulted in this performance is not unimaginable in smart home or environment. This performance degradation is partly due to lack of coordination across the layers of the protocol stack: RPL is unaware of the changes in the wireless environment underneath and proceeds as usual. As other research has shown, coordination across the network stack is essential for network protocols to work reliably in the presence of interference. This will require a more coordinated approach to standards across the bodies. [ABSTRACT FROM PUBLISHER]

Troubleshooting network outages is a complex and time-consuming process. Network administrators are typically overwhelmed with large volumes of monitoring data, like SMTP and NetFlow measurements, from which it is very hard to separate between actionable and non-actionable events. In addition, they can only debug network problems using very basic tools, like ping and traceroute. In this context, intelligent correlation of measurements from different Internet locations is essential for analyzing the root cause of outages. However, correlating measurements across domains raises privacy concerns and hence is largely avoided. A possible solution to the privacy barrier is secure multi-party computation (MPC), that is, a set of cryptographic methods that enable a number of parties to aggregate private data without revealing sensitive information. In this article, we propose a distributed mechanism based on MPC for privacy-preserving correlation of NetFlow measurements from multiple ISPs, which helps in the diagnosis of network outages. We first outline an MPC protocol that can be used to analyze the scope (local, global, or semi-global) and severity of network outages across multiple ISPs. Then we use NetFlow data from a medium-sized ISP to evaluate the performance of our protocol. Our findings indicate that correlating data from several dozens of ISPs is feasible in near real time, with a delay of just a few seconds. This demonstrates the scalability and potential for real-world deployment of MPC-based schemes. Finally, as a case study we demonstrate how our scheme helped analyze, from multiple domains, the impact that Hurricane Sandy had on Internet connectivity in terms of scope and severity. [ABSTRACT FROM PUBLISHER]

In part I of this article we presented the design alternatives, issues, and challenges for designing backhaul for 2G (GSM, CDMA) and 3G (UMTS, CDMA2000) radio access networks (RANs). Part II extends the survey of backhaul technologies to address LTE-based RANs. We present various alternatives to deal with the specific requirements imposed by Evolved Packet System architecture on the backhaul design. In particular, we address handling of the X2 interface, network security through IPSec, distribution of frequency and phase synchronization, the impact of small cell design, self-organizing networks, and endend QoS management within backhaul. We also present a brief overview of active debates with respect to some of these design options as open issues, in particular the impact of LTE-Advanced requirements on LTE backhaul design. [ABSTRACT FROM PUBLISHER]

This article presents the challenges and compares the alternatives to interoperate between SIP-based systems and the emerging standards for web real-time communication (WebRTC). We argue for an endpoint- and web-focused architecture, and present both sides of the SIP in JavaScript approach. Until WebRTC has ubiquitous cross-browser availability, we suggest a fallback strategy for web developer: detect and use HTML5 if available; otherwise, fall back to a browser plugin. [ABSTRACT FROM PUBLISHER]

This paper briefly describes Internet development in the Republic of Korea (South Korea), which started research and development on computer networking in the late 1970s. Korea became one of the first countries to deploy the Internet in 1982 [1], and organized one of the first global Internet conferences in 1985 [2]. In the late 1990s, Korea put much effort into development of broadband networks, starting from a master plan in 1995. Korea became a world leader with widely available wired and wireless broadband networks. Korea also led in Internet applications including online games, search engines and social networking services. As one of the earlier Internet countries, Korea has been vulnerable to newly arising problems on the Internet such as cybersecurity, net abuse and game addiction. Korea has been trying to solve these problems in collaboration with other leading countries. Korea has also shared its Internet experience with other countries, in particular with developing countries. A book is in preparation on the early history of the Internet in Korea [3] together with another, co-authored with Internet pioneers in other countries, on the early history of the Internet in Asia. [ABSTRACT FROM PUBLISHER]

Sleep scheduling is a widely used strategy for saving the energy of sensor nodes and prolonging the lifetime of a wireless sensor network (WSN). The lower the duty cycle is, the longer the network lifetime will be. However, sleep scheduling brings great challenges to the design of efficient distributed routing protocols for multi-hop duty-cycled WSNs. This issue has attracted much attention and various routing protocols have been proposed. In this article we first summarize the fundamental issues in the design of routing protocols for such networks, and then classify existing protocols based on different design criteria. We then present a survey of state-of-the-art routing protocols in this area. We illustrate how different protocols work and discuss their merits and deficiencies. Finally, we point out some future directions for routing in duty-cycled wireless sensor networks. [ABSTRACT FROM PUBLISHER]