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Given the unsettled debate about the role of nativeness and/or expertise in academic writing, we compared the first language (L1)-English expert writers and the Second language (L2)-English (Chinese L1) expert writers with a similar expertise level in the use of stance complement that-clauses. For our analysis, we selected equal numbers of published research articles written by the L1 and the L2 experts in the field of Telecommunications. We found considerable differences between the two groups of writers in terms of frequency, range, and semantic classes of words controlling that-clauses. First, although both the L1 experts and the L2 experts overwhelmingly used verb + that-clauses, they demonstrated relatively different syntactic preferences for stance construction. The L2 experts used more verb + that-clauses than the L1 experts, while the L1 experts utilized more noun + that-clauses. Second, the L2 experts were more likely to express greater certainty towards the claims in that-clauses than the L1 experts. Third, the L2 experts employed a narrower range of words controlling that-clauses than the L1 experts in all the semantic classes. These findings suggest that the nativeness status of academic writers still influences their use of evaluative that-clauses even at an advanced level. [ABSTRACT FROM AUTHOR]

The design of optical devices such as lasers and semiconductor optical amplifiers for telecommunication applications requires polarization insensitive optical emissions in the region of 1500 nm. Recent experimental measurements of the optical properties of stacked quantum dots have demonstrated that this can be achieved via exploitation of inter-dot strain interactions. In particular, the relatively large aspect ratio (AR) of quantum dots in the optically active layers of such stacks provide a two-fold advantage, both by inducing a red shift of the gap wavelength above 1300 nm, and increasing the TM001-mode, thereby decreasing the anisotropy of the polarization response. However, in large aspect ratio quantum dots (AR > 0.25), the hole confinement is significantly modified compared with that in lower AR dots-this modified confinement is manifest in the interfacial confinement of holes in the system. Since the contributions to the ground state optical intensity (GSOI) are dominated by lower-lying valence states, we therefore propose that the room temperature GSOI be a cumulative sum of optical transitions from multiple valence states. This then extends previous theoretical studies of flat (low AR) quantum dots, in which contributions arising only from the highest valence state or optical transitions between individual valence states were considered. The interfacial hole distributions also increases in-plane anisotropy in tall (high AR) quantum dots (TE110 ≠ TE-110), an effect that has not been previously observed in flat quantum dots. Thus, a directional degree of polarization (DOP) should be measured (or calculated) to fully characterize the polarization response of quantum dot stacks. Previous theoretical and experimental studies have considered only a single value of DOP: either [110] or [-110]. [ABSTRACT FROM AUTHOR]

This paper is a longer version of the one that won the 2005 MRS/AURA Insight Effectiveness Award. The award was for 'the best demonstration of using multiple sources of customer data to advise the board on future strategic direction'. It is a case study of defensive marketing in the telecommunications industry, which uses a combination of sales data, qualitative research, tracking studies, observation and the construction of a customer panel. It also discusses how senior company management, insight managers and research agencies can improve the insight process. [ABSTRACT FROM AUTHOR]

This study distinguishes alternative competitive and institutional explanations of interorganizational mimicry by examining the clustering of U.S. telecommunications firms' 1995--95 moves into other Western Hemisphere countries. Mimicry of entry moves was more likely when both a focal firm and prior movers had large shares in the same domestic markets. More mimicry occurred among oligopolistic long-distance firms than among monopolistic local-exchange phone companies. Thus, mimetic international entry was strongly linked to the structure of domestic competition. [ABSTRACT FROM AUTHOR]

This paper explores the effects of partner substitutability and alliance network structure on organizational profitability. Although firms are expected to benefit from the exclusive resources brought in by resource-rich, nonsubstitutable alliance partners, the costs of allying with such partners could offset those benefits. Analyzing alliances in the U.S. telecommunications industry, we show that a firm facing nonsubstitutable partners was better off when its alliances were embedded in third-party ties, which allowed the firm to gain indirect leverage on such partners. [ABSTRACT FROM AUTHOR]

The article focuses on the role of the telecommunications policy in the economic development of Europe and whether such development poses a threat for American businesses. The economic, industrial, and technological policies of the European Community (EC) are reviewed, and the EC's commitment to develop a telecommunications and information technology infrastructure are discussed. A SWOT analysis of the telecommunications policy is provided, and the implications of European integration for the United States telecommunication industry are considered.

With the rapid and bursting development of communication engineering and some related techniques, spread spectrum communication and sparse analysis have been a hot research topic in the research community. A novel anti-jamming driven sparse analysis-based spread spectrum communication methodology is proposed in this paper, which mainly increases the spread spectrum modulation and the spread spectrum demodulation in the receiving end. The process of spread spectrum communication according to the working methods of different methodologies including direct-sequence spread spectrum. In this paper, the sparse presentation, dictionary learning, anti-jamming analysis and the basic communication theories are integrated altogether to enhance the traditional spread spectrum communication analysis framework. The experimental result proves the robustness of the proposed method. [ABSTRACT FROM AUTHOR]

In an attempt to develop an understanding of existing research trends and to inform the development of new research in the field of telecommunications, literature reviews are being conducted. As an effort for investigating research trend, our research suggests the application of a text mining analysis technique to identify the knowledge structures of academic research in the field of telecommunications policy and to pinpoint future research opportunities. In this study, three analytical techniques were employed: a productivity analysis; a contents analysis based on topic modeling and word co-occurrence; and an author co-citation analysis based on a hierarchical clustering algorithm, multidimensional scaling, and a factor analysis. The findings from the research productivity analysis imply that the journal ‘Telecommunications Policy’ has greatly contributed to the publication of studies related to telecommunications policy. Moreover, our research institution analysis results indicate that telecommunication policy studies are undertaken by experts in various research fields. The contents and citation analysis results demonstrate that many studies related to telecommunications policy cover infrastructure-related topics, including the design, arrangement, and distribution of telecommunications networks. By contrast, recent studies are found to focus on the privacy and digital divide issues that may arise in connection with the application of telecommunications networks to other information technologies or industrial areas. However, the area of policy research that focuses on the application of information technologies still concentrates on the methods for the application of existing services—such as broadcasting and multimedia—without paying sufficient attention to the policy issues that may arise from the application of cloud computing, the Internet of Things, or big data analytics, services that have emerged with the recent expansion of wireless communications networks. In this sense, there is a need for discussions about the policies to respond to the increasing use of radio frequencies owing to the expansion of the Internet of Things, and to promote the efficient and safe control of data transmitted in real time on the wireless Internet. Studies of new technologies in the telecommunications policy field should be carried out in view of local and national characteristics. At the same time, further studies should consider efficient and reasonable ways to export telecommunications and networking technologies to countries that seek to invest in or expand their telecommunications networks to new information technologies. Expanding on this research, more text mining techniques for analyzing large amounts of text data and for clustering and visualizing them need to be considered. [ABSTRACT FROM AUTHOR]

The present study aimed at analyzing the publication pattern of highly cited research publications of Internet of Things. Web of Science citation database was used to extract data for the study. The top fifty highly cited publications were considered as the sample of this study. The data were analyzed based on publication year, document type, source title, time cited, usage count, authorship pattern, collaborative coefficient, research collaboration, and research areas. The findings revealed that majority of the publications were research articles and most of them were published in IEEE journals. Research articles written by multiple authors were more prominent than single-author publications. Researchers from USA and China preferred collaborative research and researchers from Italy preferred noninternational collaborative research. The researchers from developed western countries are highly engaging with research in Internet of Things. The most popular research areas under Internet of Things are computer science and telecommunication. [ABSTRACT FROM AUTHOR]

Tommy Flowers, born 22 December 1905, died 28 October 1998, designed the Colossus codebreaking machines. [ABSTRACT FROM AUTHOR]

Multihop propagation of situational information is a promising technique for improving beaconing performance and increasing the degree of situation awareness onboard vehicles. A possible way of achieving this is by piggybacking information on the beacon packets that are periodically sent by each vehicle in the network, as prescribed by the Dedicated Short-Range Communications standards and the European Telecommunications Standards Institute. However, prescribed limitations on beacon size imply that only information on a very small number of surrounding vehicles can be piggybacked in a beacon packet. In most traffic situations, this number is well below the typical number of vehicles within the transmission range, implying that multihop forwarding strategies must be devised to select which neighboring vehicle's information to include in a transmitted beacon. In this paper, we designed different multihop forwarding strategies and assessed their effectiveness in delivering fresh situational information to surrounding vehicles. Effectiveness is estimated in terms of both information age and the probability of experiencing a potentially dangerous situation-awareness blackout. Both metrics are estimated as a function of the hop distance from the transmitting vehicle and in the presence of different levels of radio channel congestion. The investigation is based on extensive simulations whose multihop communication performance is corroborated by real-world measurements. The results show that network-coding-based strategies substantially improve forwarding performance, as compared with a randomized strategy, reducing the average information age by up to 60% and the blackout probability by up to two orders of magnitude. We also consider the effect of multihop propagation of situational information on the reliability of a forward collision warning application and show that network-coding-based propagation yields a factor-3 improvement of reliability with respect to a randomized forwarding strategy and even higher improvements with respect to the case of no propagation. [ABSTRACT FROM PUBLISHER]

An application of computational intelligence to the problem of telecommunications call volume forecasting is proposed in this work. In particular, the forecasting system is a recurrent fuzzy-neural model. The premise and defuzzification parts of the model's fuzzy rules are static, while the consequent parts of the fuzzy rules are small block-diagonal recurrent neural networks with internal feedback, thus enabling the overall system to discover the temporal dependencies of the telecommunications time-series and perform forecasting without requiring prior knowledge of the exact order of the time-series. The forecasting performance is evaluated by using real-world telecommunications data. An extensive comparative analysis with a series of existing forecasters is conducted, including both traditional models as well as computational intelligence's approaches. The simulation results confirm the modelling potential of the proposed scheme, since the latter outperforms its competing rivals in terms of three appropriate metrics, in all kinds of calls. [ABSTRACT FROM AUTHOR]

We present an overview of the recently developed III-nitride-based optical waveguides for application in ultrafast signal processing at telecom wavelengths. We focus on different active and passive optical devices for further implementation within all-optical integrated circuits. Optical waveguides based on GaN/AlN quantum dots have been demonstrated to act as saturable absorbers requiring ∼3 pJ of input pulse energy to reach +3 dB transmittance contrast for TM-polarized light. On the contrary, sputtered-InN-based devices show −3 dB transmittance contrast associated to two-photon absorption for input pulse energies of ∼1 pJ, making them suitable to act as highly-efficient reverse saturable absorbers. Finally, the passive optical nature of waveguides based on sputtered AlN at 1.55 μm makes them suitable for further connections between different III-nitride-based active devices. [ABSTRACT FROM AUTHOR]

The telecommunications industry has used the time deviation (TDEV) very effectively for specifying network equipment clock performance as well as the performance of timing signals generated by Central Office equipment such as primary reference clocks and building integrated timing supplies (BITS) and synchronization supply units (SSUs). We discuss here the development of TDEV, and the variations of TDEV motivated by the advent of packet-switching and the steady transformation of the telecom network from circuit-switched-based to packet-switched-based. We illustrate these with simulation of the performance of the precise time protocol (PTP) across a packet-switched network. We then apply published methods to automatically determine noise types, and use these to predict time dispersion from a master clock for a slave clock using these PTP packets to stay synchronized. The result shows how TDEV and the other deviations provide an extensive array of tools for telecom networks, as well as for general time and frequency applications. [ABSTRACT FROM AUTHOR]

We show that properly designed mantle cloaks, consisting of patterned metallic sheets placed around cylindrical monopoles, allow tightly packing the same antennas together in a highly dense telecommunication platform. Our experimental demonstration is applied to the relevant example of two cylindrical monopole radiators operating for 3G and 4G mobile communications. The two antennas are placed in close proximity, separated by 1/10 of the shorter operational wavelength, and, after cloaking, are shown to remarkably operate as if isolated in free-space. This result paves the way to unprecedented co-siting strategies for multiple antennas handling different services and installed in overcrowded platforms, such as communication towers, satellite payloads, aircrafts, or ship trees. More broadly, this work presents a significant application of cloaking technology to improve the efficiency of modern communication systems. [ABSTRACT FROM AUTHOR]

Energy efficient wireless communications have recently received much attention, due to the ever-increasing energy consumption of wireless communication systems. In this paper, we propose a new energy-efficient cooperative relaying scheme that selects a subset of relays before data transmission, through proactive participation of available relays using their local timers. We perform theoretical analysis of energy efficiency under maximum transmission power constraint, using practical data packet length, and taking account of the overhead for obtaining channel state information, relay selection, and cooperative beamforming. We provide the expression of average energy efficiency for the proposed scheme, and identify the optimal number and location of relays that maximize energy efficiency of the system. A closed-form approximate expression for the optimal position of relays is derived. We also perform overhead analysis for the proposed scheme and study the impact of data packet lengths on energy efficiency. The analytical and simulation results reveal that the proposed scheme exhibits significantly higher energy efficiency as compared to direct transmission, best relay selection, all relay selection, and a state-of-the-art existing cooperative relaying scheme. Moreover, the proposed scheme reduces the signaling overhead and achieves higher energy savings for larger data packets. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the multiservice delivery between the source–destination pairs in distributed selfish wireless networks (SeWN), where selfish relay nodes (RN) expose their selfish behaviors, i.e., forwarding or dropping multiservices. Owing to the effect of the RNs’ node-selfishness on the multiservices, a distributed framework of the node-selfishness management is constructed to manage the RN’s node-selfishness information (NSI) in terms of its available resources, the employed incentive mechanism and the quality-of-service (QoS) requirements, and the other RNs’ NSI in terms of their historical behaviors. In this framework, the RNs’ NSI includes the degree of node-selfishness (DeNS), the degree of intrinsic selfishness (DeIS) and the degree of extrinsic selfishness (DeES). Under the distributed node-selfishness management, a path selection criterion is designed to select the most reliable and shortest path in terms of RNs’ DeISs affected by their available resources, and the optimal incentives are determined by the source to stimulate forwarding multiservices of the RNs in the selected path. Our simulation results demonstrate that this framework effectively manages the RNs’ NSI, and the optimal strategies of both the path selection and the incentives are determined. [ABSTRACT FROM AUTHOR]

Spectrum leasing has been proposed as an effective approach for enabling more flexible spectrum utilization in CRNs. In CRNs, a primary network (PN) which consists of multiple primary users (PUs) can lease part of the licensed spectrum to secondary users (SUs) in exchange for operational benefits. The focus of this study is to investigate how and to what extent the PN allows spectrum leasing in CRNs, considering the QoS requirements of the PN and the secondary network (SN). Correspondingly, we propose two dynamic spectrum leasing strategies, which can improve the QoS performance of SUs while ensuring sufficient remuneration for PUs. In order to dynamically adjust the portion of leased bandwidth, two forms of leasing algorithms, which are based on channel occupancy of the PN and the SN respectively are proposed. Analytical models are developed to characterize system centric performance metrics including capacity, blocking probability, and forced termination probability in both networks. Furthermore, a dynamic pricing scheme for spectrum leasing and utility-based resource allocation is introduced. Finally the performance of dynamic leasing is compared quantitatively with that of static leasing and approaches without leasing. Numerical results obtained from both analysis and simulations show that dynamically adjusted spectrum leasing improves network performance. [ABSTRACT FROM AUTHOR]

We consider the concept of faster-than-Nyquist rate (FTN) broadcasting, which nonorthogonally multiplexes more than one user message in the continuous-time domain for transmission over broadcast channels. Two FTN broadcasting approaches, namely, sub-FTN and full-FTN, are considered for broadcasting of $K$ independent messages over $K$-user continuous time Gaussian broadcast channel. The derived achievable rate regions of the two approaches are shown to be, in general, greater than the capacity region of the optimally coded Nyquist-rate broadcasting using a same modulating pulse. The full-FTN broadcasting provides larger degrees of freedom (capacity pre-log factor) to each user of the broadcast channel while the sub-FTN improves signal-to-interference-plus-noise-ratios of the individual link. The amount of capacity gains in high SNR regime is linearly proportional to excess bandwidth in the modulating pulse used and dependent on FTN signaling rates, channel SNRs, and number of users in the broadcast channel. The simulated sub-FTN and full-FTN broadcast transceivers outperform coded Nyquist-rate systems both in BER performances and in capacity. [ABSTRACT FROM AUTHOR]

This paper studies two-user cognitive multiple-input multiple-output (MIMO) interference channel with delayed channel state information at transmitter (CSIT), where a transmitter possesses noncasual knowledge of data originating at the other user. We first derive an upper bound of degrees-of-freedom (DoF) region and then propose DoF bound achieving schemes for various antenna configurations. Since interference condition and interference suppression capability vary with antenna configurations, the proposed DoF optimal schemes differently utilize cognitive transmission based on delayed CSIT to suppress interference and thus differ in the required numbers of time slots and transmit symbols, although the key idea of swapping interfering signals between users is common. Comparing with the DoF regions of relevant channels, we identify and analyze the contributions of cognitive transmission and delay CSIT toward enlarging the DoF region. Our analysis specifies antenna configurations where delayed CSIT and cognitive transmission are useful, respectively. [ABSTRACT FROM AUTHOR]

In interference channels (ICs), channel state information (CSI) can be utilized to design transmit signals that are optimally adapted to the state of the channels. This requires feeding CSI back to the transmitters. The CSI available at the transmitters (CSIT) is usually degraded, due to the limited capacity of the feedback link and the delays involved in the channel estimation and feedback. We discuss the scenario of fast fading and delayed CSIT, which is highly relevant in mobile environments with short channel coherence times. We consider the two-user multiple-input-multiple-output (MIMO) IC where the transmitters are provided with delayed CSIT. The DoF region for this channel was characterized by Vaze and Varanasi. We devise a simple and intuitive achievable scheme, which has a unified structure for different antenna configurations. We show that the proposed scheme also achieves the DoF region of the two-user MIMO broadcast channel (BC). In the IC, our scheme does not require the knowledge of direct channels at the transmitters. Moreover, we show that the amount of feedback can be further reduced by exploiting the invariances of the problem. Our approach can be helpful when analyzing more complicated networks. [ABSTRACT FROM AUTHOR]

This paper proposes a new compressive sensing-based downlink channel state information (CSI) estimation scheme for frequency division duplexing (FDD) massive multiple-input multiple-output (MIMO) systems. The proposed scheme, which involves two-stage weighted block \ell _1-minimization, exploits the block sparse nature of the angular domain representation of the MIMO channel matrices and the existence of common scattering paths in the realistic propagation environment. In the first stage of the implemented scheme, a conventional block \ell _1-minimization program is solved to extract the information about the common/individual supports of the multiuser channel matrices. In the second stage, a weighted block \ell _1-minimization algorithm, the weighting coefficients of which are suitably chosen to exploit the acquired support information, is used to estimate the channel matrices. The analytic performance guarantees of the proposed scheme are specified based on the block restricted isometry property of the sensing matrix. Specifically, the upper bounds of the \ell _2-norm reconstruction error are derived using various assumptions regarding the weighting. The obtained analytical results enable a discussion of the selection of weighting coefficients to enhance the CSI estimation performance, and the determination of a sufficient condition under which the proposed scheme outperforms the unweighted naive solution. Computer simulations show that the proposed method achieves higher estimation accuracy as compared to an existing greedy-based algorithm. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) systems using the indoor lighting system to also provide downlink communications require high-average optical powers to satisfy the illumination needs. This can cause high-amplitude signals common in higher-order modulation schemes to be clipped by the peak power constraint of the light emitting diode (LED) and lead to high-signal distortion. In this paper, we introduce Hadamard coded modulation (HCM) to achieve low error probabilities in LED-based VLC systems needing high-average optical powers. This technique uses a fast Walsh–Hadamard transform (FWHT) to modulate the data as an alternative modulation technique to orthogonal frequency division multiplexing (OFDM). HCM achieves a better performance for high-illumination levels because of its small peak to average power ratio (PAPR). The power efficiency of HCM can be improved by reducing the DC part of the transmitted signals. The resulting so-called DC-reduced HCM (DCR-HCM) is well suited to environments requiring dimmer lighting. [ABSTRACT FROM AUTHOR]

Based on the efficient generalized water-filling with group peak power constraints (GWFGP), this paper proposes an iterative algorithm to compute the optimal solutions to system throughput (sum-rate) maximization problems. This class of problems is equipped with the multiuser multiple input multiple output multiple access channels (MU-MIMO MAC) in the general communication systems. The proposed iterative GWFGP algorithm (IGWFGP) has two levels of loops. The inner loop aims at computing the solution to each member in the family, while the outer loop aims at computing the solution to the target problem based on the results obtained by the inner loop. Both GWFGP and the convergence theory of an algorithm are used in the inner loop and the outer loop respectively. Furthermore, by exploiting the concept of variable weighting factor for covariance update, IGWFGP owns fast convergence and provides optimal solutions to the sum rate maximization problems. The usage of the convergence theory in IGWFGP and the algorithm of GWFGP are efficient and novel. To the best of the authors’ knowledge, no prior algorithm has been reported in the open literature to solve the targeted problem in this paper. In addition, the proposed algorithm does not require to choose the initial value for computation. This feature is a significant advantage of the algorithm, especially for large and complicated systems. [ABSTRACT FROM AUTHOR]

Energy harvesting (EH) has recently emerged as a key technology for green communications as it can power wireless networks with renewable energy sources. However, directly replacing the conventional non-EH transmitters by EH nodes will be a challenge. In this paper, we propose to deploy extra EH nodes as relays over an existing non-EH network. Specifically, the considered non-EH network consists of multiple source–destination (S-D) pairs. The deployed EH relays will take turns to assist each S-D pair, and energy diversity can be achieved to combat the low-EH rate of each EH relay. To make the best of these EH relays, with the source transmit power minimization as the design objective, we formulate a joint power assignment and relay selection problem, which, however, is NP-hard. We thus propose a general framework to develop efficient suboptimal algorithms, which is mainly based on a sufficient condition for the feasibility of the optimization problem. This condition yields useful design insights and also reveals an energy hardening effect, which provides the possibility to exempt the requirement of noncausal EH information. Simulation results will show that the proposed co-operation strategy can achieve near-optimal performance and provide significant power savings. Compared to the greedy co-operation method that only optimizes the performance of the current transmission block, the proposed strategy can achieve the same performance with much fewer relays, and the performance gap increases with the number of S-D pairs. [ABSTRACT FROM AUTHOR]

The heterogeneous cellular network (HCN) is a promising approach to the deployment of 5G cellular networks. This paper comprehensively studies physical layer security in a multitier HCN where base stations (BSs), authorized users, and eavesdroppers are all randomly located. We first propose an access threshold-based secrecy mobile association policy that associates each user with the BS providing the maximum truncated average received signal power beyond a threshold. Under the proposed policy, we investigate the connection probability and secrecy probability of a randomly located user and provide tractable expressions for the two metrics. Asymptotic analysis reveals that setting a larger access threshold increases the connection probability while decreases the secrecy probability. We further evaluate the network-wide secrecy throughput and the minimum secrecy throughput per user with both connection and secrecy probability constraints. We show that introducing a properly chosen access threshold significantly enhances the secrecy throughput performance of a HCN. [ABSTRACT FROM AUTHOR]

Distributed arithmetic coding (DAC) is an effective technique for implementing Slepian–Wolf coding (SWC). It has been shown that a DAC code partitions source space into unequal-size codebooks, so that the overall performance of DAC codes depends on the cardinality and structure of these codebooks. The problem of DAC codebook cardinality has been solved by the so-called codebook cardinality spectrum (CCS). This paper extends the previous work on CCS by studying the problem of DAC codebook structure. We define Hamming distance spectrum (HDS) to describe DAC codebook structure and propose a mathematical method to calculate the HDS of DAC codes. The theoretical analyses are verified by experimental results. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a spectrum refarming system where an OFDMA system shares the licensed band of a CDMA system. Both systems share the same cell site, but each has different base station (BS) antennas. Joint resource allocation problem is formulated to optimize the CDMA receive power, OFDMA transmit power, and subcarrier assignment. Conventional interference control to protect the primary CDMA system relies on the availability of cross-channel gains (CCGs) from each secondary OFDMA transmitter to the CDMA BS receiver. However, the CCGs are difficult to be obtained due to lack of intersystem cooperation. To address this problem, we first decouple the original problem into higher and lower-level problems via primal decomposition. Then, a robust lower-level resource allocation (R-LRA) scheme, which controls interference without using CCGs is proposed, with which CDMA users can be sufficiently protected. Thereafter, an enhanced R-LRA (ER-LRA) scheme is proposed to decrease the conservation of R-LRA scheme. Assisted by the CDMA inner power control and based on the ER-LRA, efficient algorithm is designed to solve the higher-level problem. Extensions of the ER-LRA for other scenarios are also studied. Simulation results are provided to validate the proposed schemes in facilitating and improving the spectrum sharing performance. [ABSTRACT FROM AUTHOR]

In cognitive radio networks, the cross-channel gain from a cognitive transmitter (CT) to a primary receiver (PR) is critical for spectrum sharing and obtaining the cross-channel gain is very difficult. Even though proactive estimation allows the CT to autonomously estimate the cross-channel gain, it may cause severe interference to the PR. This raises a new issue for spectrum sensing, called spectrum sensing interference. In this paper, we deal with the sensing interference and propose a relay-assisted method to conduct the proactive estimation, which obtains the cross-channel gain with much less interference to the PR. In our method, we let the CT act as a full-duplex amplify-and-forward relay to probe the close-loop power control between primary transceivers. By measuring the power adjustment of the primary signal, the CT estimates the cross-channel gain. Simulation results indicate that our method can reduce the sensing interference to an extremely low level. [ABSTRACT FROM AUTHOR]

Machine-to-machine (M2M) communication’s severe power limitations challenge the interconnectivity, access management, and reliable communication of data. In densely deployed M2M networks, controlling and aggregating the generated data is critical. We propose an energy-efficient data aggregation scheme for a hierarchical M2M network. We develop a coverage probability-based optimal data aggregation scheme for M2M devices to minimize the average total energy expenditure per unit area per unit time or simply the energy density of an M2M communication network. Our analysis exposes the key tradeoffs between the energy density of the M2M network and the coverage characteristics for successive and parallel transmission schemes that can be either half-duplex or full-duplex. Comparing the rate and energy performances of the transmission models, we observe that successive mode and half-duplex parallel mode have better coverage characteristics compared to full-duplex parallel scheme. Simulation results show that the uplink coverage characteristics dominate the trend of the energy consumption for both successive and parallel schemes. [ABSTRACT FROM AUTHOR]

We consider the problem of oblivious transfer (OT) over OFDM and MIMO wireless communication systems where only the receiver knows the channel state information. The sender and receiver also have unlimited access to a noise-free real channel. Using a physical layer approach, based on the properties of the noisy fading channel, we propose a scheme for honest-but-curious parties that enables the transmitter to send obliviously one-of-two files, i.e., without knowing which one has been actually requested by the receiver, while also ensuring that the receiver does not get any information about the other file. [ABSTRACT FROM AUTHOR]

In this paper, we consider the secrecy capacity of a wiretap channel in the presence of causal state information and secure rate-limited feedback. In this scenario, the causal state information from the channel is available to both the legitimate transmitter and the legitimate receiver. In addition, the legitimate receiver can send secure feedback to the transmitter at a limited rate $R_f$. We derive upper and lower bounds on the secrecy capacity and show that, when the channel to the eavesdropper is degraded, the bounds are tight and the secrecy capacity is completely characterized. The capacity achieving scheme is based on Wyner, Csiszár, and Körner wiretap coding and two steps of shared-key generation: one from the state information and one via the noiseless feedback. The upper bound is more involved and requires a nontrivial recursive lemma extending previous results in the literature to include both state and feedback. We conclude the paper by showing that a few interesting known results can be seen as special cases of the above, as well as discussing the case where the source of local randomness at the encoder is limited. [ABSTRACT FROM AUTHOR]

We consider a three-node buffer-aided relaying network with statistical quality-of-service (QoS) constraint in terms of maximum acceptable end-to-end queue-length bound outage probability. In particular, we study the adaptive link selection relaying problem that aims to maximize the constant supportable arrival rate $\mu$ to the source (i.e., the effective capacity). Fixed and adaptive source and relay power allocation are investigated. By employing asymptotic delay analysis, we first convert the QoS constraint into minimum QoS exponent constraints at the source and relay queues. We then derive the link selection and power allocation solutions as functions of the instantaneous link conditions and QoS exponents using Lagrangian approach. Solutions for various special cases of link conditions and QoS constraints are presented. Moreover, we compare the effective capacities of the proposed relaying schemes and other existing schemes under different link conditions and QoS constraints. Illustrative results indicate that the proposed schemes offer substantial performance gains, and power adaption outperforms fixed power allocation at low signal-to-noise power ratio (SNR) region or under loose QoS constraints. [ABSTRACT FROM AUTHOR]

The current cellular networks have evolved to be more randomly, irregularly, and heterogeneously deployed to meet the exponential growth of mobile data traffic and the demand for seamless coverage, making the signal-to-interference ratio (SIR) distribution more challenging to analyze. Therefore, in this paper, we propose two simple approximative approaches to the SIR distribution of general heterogeneous cellular networks (HCNs) based on the ASAPPP method, which stands for “approximate SIR analysis based on the Poisson point process” and the MISR (mean interference-to-signal ratio)-based gain for each individual tier of the HCNs. Specifically, we first establish a per-tier ASAPPP approximation to general HCNs and then present an effective gain ASAPPP method as a further simplification when the path loss exponents are the same for all the tiers, that is, we give an explicit expression for the effective gain G\rm{ eff} of general HCNs such that the SIR distribution is obtained by scaling the SIR threshold \theta to \theta/G_{\rm{ eff}} . The asymptotic behavior for the tail of the SIR distribution is also given. Furthermore, to highlight the simplicity and effectiveness of the approximative approaches, we derive the exact distribution of the SIR in the two-tier HCNs modeled by \beta$-Ginibre and Poisson point processes and compare it with the approximate results. The results demonstrate that the proposed approaches give a simple yet excellent approximation for the SIR distribution. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) inherently suffers from two major drawbacks: high out-of-band (OOB) power leakage and high peak-to-average power ratio (PAPR). This paper proposes a novel approach called suppressing alignment for the joint reduction of the OOB power leakage and PAPR. The proposed approach exploits the temporal degrees of freedom provided by the cyclic prefix (CP), a necessary redundancy in OFDM systems, to generate a suppressing signal, that when added to the OFDM symbol, results in marked reduction in both the OOB power leakage and PAPR. Additionally, and in order to not cause any interference to the information data carried by the OFDM symbol, the proposed approach utilizes the wireless channel to perfectly align the suppressing signal with the CP duration at the OFDM receiver. Essentially, maintaining a bit error rate (BER) performance similar to legacy OFDM without requiring any change in the receiver structure. [ABSTRACT FROM AUTHOR]

Evolution in the telecommunications networks and the rapid advances made in wireless mobile communication networks, have taken computer networks to a new communication level. They now provide support for new mobile multimedia applications and are thus fostering the development of new network types and configurations. MANET is an important configuration of network for operations that employ mechanisms to enable dynamic self-configuration, self-optimization and self-healing, which is a challenging task for the routing protocols, new multimedia application and the battery energy consumption of wireless and mobile devices. These protocols are challenging because battery problems are more serious in this type of network and the existing protocols are not adapted to current problems, particularly mobile multimedia streaming, that can be found in most Internet flow. This paper proposes a reliable energy-efficient multilayer mechanism to address this to make improvements in the main current protocols. The proposal adds decision metrics to an energy-efficient computational intelligence technique based on Fuzzy-System with QoE, mobility and battery guarantees, choosing the best path in an efficient and accuracy way. The proposal has been evaluated in a network simulator. [ABSTRACT FROM AUTHOR]

A growing body of literature suggests that the segregation of infrastructure and urban/regional planning is at the root of contemporary problems facing many of the world's metropolitan areas. More recently, the introduction of new telecommunication infrastructure highlights the invisible borders that exist within critical infrastructure that provide advantages to some areas such as transportation and disadvantages to others. This paper attempts to understand the nature of inter-sectoral and intra-sectoral borders across infrastructure in Australia and the US. It examines the sometimes contradicting market-led vs. government-led models adopted in the two countries to deliver broadband communications and transportation. The findings identify similarities and differences between the two countries, and reiterate that in order to achieve social equity, and enhance the provision of infrastructure to non-profitable areas, government intervention is required. The paper concludes with a call for performance-based policies that go beyond traditional borders in an effort to better address the contemporary wicked planning problems. [ABSTRACT FROM PUBLISHER]