Telecommunication Systems

Today, cyber deception is an essential element of proactive and reactive defense systems. Military equipment is increasingly connected to the Internet, and next-generation network security is becoming increasingly complex. This vast network of military tactics thus becomes exposed and vulnerable, opening a battlefield against cyberattacks. The security of such a network is therefore paramount. In this paper, we propose a game-theoretic cyber deception approach for the allocation of diversified honeypots. To ensure high availability of our security measure, we opt for diversified redundancy in honeypot placement. We will analyze the impact on the defender's reward, with or without the attacker's success probability. The optimization will be solved using the Nash balance. Regarding honeypot placement, we adopt a deployment with redundancy to guarantee the security of critical nodes. Our results show that redundancy strengthens the ability to diversify the honeypot, thus ensuring long-term network security.

Today, cyber deception is an essential element of proactive and reactive defense systems. Military equipment is increasingly connected to the Internet, and next-generation network security is becoming increasingly complex. This vast network of military tactics thus becomes exposed and vulnerable, opening a battlefield against cyberattacks. The security of such a network is therefore paramount. In this paper, we propose a game-theoretic cyber deception approach for the allocation of diversified honeypots. To ensure high availability of our security measure, we opt for diversified redundancy in honeypot placement. We will analyze the impact on the defender's reward, with or without the attacker's success probability. The optimization will be solved using the Nash balance. Regarding honeypot placement, we adopt a deployment with redundancy to guarantee the security of critical nodes. Our results show that redundancy strengthens the ability to diversify the honeypot, thus ensuring long-term network security.

We carried out modeling and simulation of the noise properties associated with types of modal oscillations induced by scaling the asymmetric gain suppression (AGS) in multimode semiconductor lasers. The study is based on numerical integration of a system of rate equations of 21-oscillating modes taking into account the self-and cross-modal gain suppression mechanisms. AGS is varied in terms of a predefined parameter, which is controlled by the linewidth enhancement factor and differential gain. Basing on intensive simulation of the mode dynamics, we present a mapping (AGS versus current) diagram of the possible types of modal oscillations. When the laser oscillation is hopping multimode oscillation (HMMO), the spectra of relative intensity noise (RIN) of the total output, and hopping modes are characterized by a sharp peak around the relaxation oscillation frequency and a broad peak around the hopping frequency. The levels of RIN in the regimes of single-mode oscillation are much lower than those under HMMO, and the mode-partition noise is two orders of magnitudes lower.

This paper introduces analysis ofmode dynamics in multiple-quantum well (MQW) laser as a promising device for high-speed photonics. The study is based on a multimode model of semiconductor laser under direct intensity modulation. The simulation results are used to investigate the influence of the injection current on the dynamics of the non-modulated multimode laser, as well as influence ofthe modulation parameters (modulation index and modulation frequency) on the dynamics of the laser. The modal oscillations and the associated multimode hopping that characterizes the long-wavelength laser are investigated in both the non-modulated and modulated laser. The coupling among the oscillating modes under both cases is evaluated in terms oftheir correlation coefficients. Dependence of the small-signal modulation response and bandwidth on the bias current is introduced. In addition, we present comparison of the modulation response of the total output with those of the strongest o s cillating mo de s.

This paper introduces a theoretical study on the influence of intermodal asymmetric gain suppression (AGS) on dynamics and output of multimode semiconductor lasers. The study includes comprehensive and intensive simulations of the dynamics of 21-oscillating longitudinal modes taking account of the self-and crossmodal gain suppression mechanisms. AGS is varied in terms of a pre-defined parameter, 𝐻 𝑐 , that combines the linewidth enhancement factor and differential gain as controlling parameters of AGS. We classify laser oscillation into four types, namely, single mode oscillation (SMO), symmetric steady-state multimode oscillation (SSMMO), asymmetric steady-state multimode oscillation (ASMMO) and hopping multimode oscillation (HMMO) depending on the values of 𝐻 𝑐 and injection current. We allocate the operating regime of each of these classes over a mapping diagram of 𝐻 𝑐 versus current. SMO is attained when the current increases beyond the threshold and 𝐻 𝑐 has small values. Jumping of the oscillating mode on the long-wavelength side is noticed by increasing 𝐻 𝑐. When 𝐻 𝑐 increases and violates AGS, HMMO is induced among a number of modes, and asymmetric output spectra are obtained. In this case the mode-hopping frequency ranges between 36 and 392 MHz and the hopping modes are anti-correlated with correlation coefficient exceeding-0.25.

We consider the joint carrier frequency offset (CFO) and channel estimation for OFDM systems. A novel frequency offset estimator is derived based on maximum likelihood principles by using the pilot symbols embedded in each OFDM symbol. An iterative joint CFO and channel estimator is proposed to further reduce the estimation error and improve the system performance. The joint estimator is initialized with the first CFO estimate and linearly interpolated channel estimates. The CFO and channel response estimates are updated by maximum likelihood (ML) and least squares (LS) algorithms. Simulation results show that the proposed joint estimator is effective and can achieve excellent bit error rates in just one iteration.

Quality of Experience (QoE) is a metric that quantifies the quality experienced while using a service. This is a subjective metric that is crucial for determining the level of satisfaction with the quality of services, such as multimedia streaming or games. Because of its subjective character, QoE is estimated accurately by executing complex and cumbersome subjective studies, or not as accurately by using objective signal distortion metrics. In order to get the accuracy of the subjective approach and the practicality of the objective, we ...

We investigate the problem o f designing reconfigurable embedding schemes for a fixed hypercube (without redundant processors and links). The fundamental idea for these schemes is to embed a basic network on the hypercube without fully utilizing the nodes on the hypercube. The remaining nodes can be used as spares to reconfigure the embeddings in case of faults. The result of this research shows that by carefully embed ding the application graphs, the topological properties of the embedding can be preserved under fault conditions, and reconfiguration can be carried out efficiently. In this dissertation, we choose the ring as the basic network of interest, and propose several schemes for the design o f reconfigurable embeddings with the aim of minimizing reconfiguration cost and performance degradation. The cost is measured by the number of node-state changes or reconfiguration steps needed for processing of the reconfigura tion, and the performance degradation is characterized as the dilation of the new embed ding after reconfiguration. Compared to the existing schemes, our schemes surpass the existing ones in terms of applicability of schemes and reconfiguration cost needed for the resulting embeddings. A. Failure M odel.

In this paper, an expression for the channel capacity (CC) of the combined L-branch (SC) selection receiver is derived in the presence of Rayleigh small fading and co-channel interference (CCI) also by Rayleigh distribution. Rayleigh fading occurs when there is a large number of objects between the transmitter and receiver on which the signal scatters. Analytical results for CC will be performed in closed form and then graphed for channel capacity. In addition, a machine learning approach based on ChatGPT is introduced to recognize the type of fading based on channel capacity measurements, which is further leveraged for quality of service (QoS) adjustment tuning the corresponding parameters on receiver's side.

In today’s competitive market, the customer retention represents one of the focal concern for telecommunications companies. The telecommunications sector can be considered on the top of the list with an annual churn rate of approximately 30%. Since the cost associated with subscriber acquisition is higher than the cost of subscriber retention, the need for predictive models to identify subscribers that are at risk of churning has become an important aspect for modern telecommunications operators. But, because the pre-paid mobile telephony market is not easily traceable and definable, implementing a predictive model would be a complex process. In this paper, we present an advanced methodology that helps to predict subscribers churn in pre-paid mobile telecommunications industry, by applying data mining algorithms on dataset that contains call details records. To construct the models we will use k-nearest neighbor, logistic regression, and bayesian networks algorithms. To evaluate and...

Relaying is a promising enhancement to current radio access networks. Relay enhanced LTE-Advanced networks are expected to fulfill the demanding coverage and capacity requirements in a cost-efficient way. However, due to low transmit power, the coverage areas of the relay nodes will be small. Therefore, the performance of relay deployments may be limited by load imbalances. In this study, we present a practical solution for this problem by introducing a bias to cell selection and handover decisions along with a reduction in eNB transmit power. This method results in an extension of the relay cells and an appropriate load balance can then be achieved. Moreover, it is shown that a proper power control setting is necessary in the uplink and that power control optimization can further enhance the system performance. Comprehensive system level simulations confirm that the proposed solution yields significant user throughput gains both in the uplink and the downlink.

Software Defined Network (SDN) is a developing innovation which actualizes the decoupling of the control plane from the system components, for example, switches or switches and keeps just the information plane with them. This separation provides a more efficient method for development of more complex and advanced applications that are not vendor specific. In SDN, the control plane which decides how to forward the packets is separated from the network elements and hence the forwarding decisions are made only at SDN Controller, with exceptions when the Network Administrator leaves some control functions to the forwarding elements. In this paper, effort has been made to mitigate two major layer two attacks which are common. A Port Blocker and VLAN Application is written and tested in a POX controller based environment all simulated in Mininet and tested to determine their efficacy.

Internet radio broadcasting emerged as a dynamic media that enables the delivery of audio content through various devices and network conditions. This paper investigates the technical foundations of Internet radio, focusing on the critical role of audio encoding in optimizing bandwidth usage, listener experience, and device compatibility. Major audio codecs like MP3, AAC/AAC+, Opus, Ogg Vorbis, and FLAC are systematically reviewed and are analyzed by their suitability for various genres and various scenarios. Through comparative tables and academic diagrams, it is demonstrated that AAC+ offers superior performance for low-bitrate classical streams, while Opus excels in adaptive environments and talk formats. The study provides actionable recommendations for internet radio stations by emphasizing codec selection that can be changed and chosen by the content type and needs of audience.

This paper addresses the problem of capacity pro- visioning in a QoS enabled IP network, subject to satisfying varying performance requirements for different traffic classes. These performance requirements are viewed in terms of mean end-to-end delays required for the various traffic classes or in terms of random variations of their delays (i.e., jitter) or a combination of both. The accuracy of the model is investigated by means of a simulation study over an extended range of test cases for different traffic load characteristics and traffic intensities at the nodes. The results demonstrate the capability of the model in guaranteeing the end-to-end delay requirements for the traffic classes. procedures that allow burstiness of multi-class IP traffic to be effectively modelled. The selection of a renewal traffic model i.e., GI arrival process, for this purpose, represents a reasonable bal- ance between the accuracy (modelling power) and the efficiency required by a network planning t...

Mobile ad hoc networks typically use a common transmission power approach for the discovery of routes and the transmission of data packets. In this paper we present PCQoS; a power-controlled Quality of Service (QoS) scheme for wireless ad hoc networks which builds QoS mechanisms for specific applications that wish to tradeoff better QoS performance for sub-optimal paths. PCQoS allows selected flows to modify their transmit power as a way to add and remove relay nodes from their paths in order to coarsely modify their observed application QoS performance. We present simulation results and show that PCQoS can be used to provide coarse control over traditional QoS metrics (e.g., delay, throughput). To the best of our knowledge the PCQoS protocol represents the first attempt to use variable-range transmission control as a means to provide QoS differentiation to applications in wireless ad hoc networks.

Traditional data acquisition methods for wireless sensor networks (WSNs) require all sensor nodes to transmit at least once to the sink node to obtain a full view of the network. In this paper we present Disagree, a different data acquisition method to retrieve data in WSNs that works in the opposite way as compared with traditional methods. In Disagree, only nodes that do not satisfy an assertion are required to transmit data back to the sink node in order to obtain a complete view of the network. We show that this behavior is the base of an energy-efficient way to gather all data. An important feature of Disagree is that it saves energy at the sensor level by exploiting data correlation. Rather than requesting explicit data readings from all sensor nodes, Disagree estimates the readings from sensor nodes that did not respond to the assertion. As a result of this policy, Disagree can obtain a view of the sensing field with different levels of resolution involving the transmission of only a subset of the sensor nodes by exploiting spatial data redundancy. We implemented Disagree in NS-2 network simulator and results indicate Disagree can significantly reduce the percentage of nodes replying to queries compared with flat and a cluster head based approaches.

New paradigms are being proposed to cope with the increasing traffic demand in the access networks. One alternative is to leverage cost-efficient VCSEL-based Sliceable Bandwidth Variable Transceivers (S-BVTs) near the edge. In this work, we investigate the adoption of optical S-BVTs for the transport of cellular traffic. A dynamic and decentralized orchestration algorithm is proposed to achieve an optimal user association and resource allocation of the access network's resources while considering the load-balancing and availability of the underlying optical infrastructure. Two association and resource allocation techniques are explored in a two-tier heterogeneous network featuring different radio access technologies. The results show that the decentralized solution outperforms the coverage mapsbased association and exhibits load balancing capabilities without the need of a centralized coordination, which can be leveraged by the S-BVT's adaptive capabilities.

Wireless communications are radically changing the way we communicate and live. While wireless communications for, e.g., computers communications and cellular telephony are a commodity nowadays, another important paradigm (an extension of the above technologies) is entering our lives, which are wireless sensor networks. In particular human centered networks of this kind are going to play an important role and they are referred to as Wireless Body Area Networks (WBAN), or (when exposing the importance of sensors) as Wireless Medical Sensor Networks (WMSN). Clearly, when these latter networks are used for medical purposes, security and privacy are of utmost importance. And while quite a substantial body of literature nowadays acknowledges this issue, this body remains rather limited as far as complete solutions are concerned. Therefore this paper provides a recap of some relevant papers in this area, and further extends them by exposing the need for the big picture approach to securit...

The network field has been very popular in recent times and has aroused much of the attention of researchers. The network must keep working with the varying infrastructure and must adapt to rapid topology changes. Graphical representation of the networks with a series of edges varying over time can help in analysis and study. This paper presents a novel adaptive and dynamic network routing algorithm based on a Regenerate Genetic Algorithm (RGA) with the analysis of network delays. With the help of RGA at least a very good path, if not the shortest one, can be found starting from the origin and leading to a destination. Many algorithms are devised to solve the shortest path (SP) problem for example Dijkstra algorithm which can solve polynomial SP problems. These are equally effective in wired as well as wireless networks with fixed infrastructure. But the same algorithms offer exponential computational complexity in dealing with the real-time communication for rapidly changing networ...

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Researchers are directing enormous efforts to achieve the aim of global mobility by enhancing the standard mobile IP with various routing schemes focusing on best routes and least cost while ignoring the facts of the organizations usual use of private IP’s and the presence of firewalls. Nevertheless, existing Mobile IP models are still missing three basic concepts that hinder their applicability in real environment. First, global mobility must be independent of the different infrastructure technologies (e.g., Wi-Fi, WiMAX, UMTS, etc.). Second, a secure authentication mechanism for guiding the access of mobile nodes to the corporate network’s resources is certainly needed. Third, the capability of correlating the mobile node’s activities to a real world identity is a requirement of security in a wider since i.e., network, web, and national security. This paper defines the role of global mobility in facilitating and improving mobile business performance. It, also, presents a review of...

The Internet Exchange Point (IXP), an Ethernet fabric central to the structure of the global Internet, is largely absent from community-driven collaborative network infrastructure. IXPs exist in central, typically urban, environments where strong network infrastructure ensures high levels of connectivity. Between rural and remote networks, separated by distance and terrain, no such infrastructure exists. In this paper we present RemIX a distributed IXP architecture designed for the community network environment. We examine this praxis using an implementation in Scotland, with suggestions for future development and research.

Modern communication systems adopt the principle of wireless communication as a basic choice in life in the city and nearby offices. Systems are often expensive and monopolized by governments and
regimes, so many researchers around the world are interested in finding systems that can be of a cheap nature, have good communication quality, and can send data at an acceptable to excellent rate. Free space optical system is one of those systems that unlicensed and cost-effective system. In this study we found the optimum wavelength for FSO system and apply it with the three main weather condition fog, rain and snow. FSO using many techniques like a LOS (line of sight) and multibeam sending data where voice, video communication and data is achieved with high data rate by bidirectional full duplex connectivity[1].
The 850 nm wavelength is very suitable for FSO system because of it’s reliable, high-performance, and inexpensive transmitter and detector components. Also, they are generally available and commonly used in today’s service provider networks and transmission equipment[6].

In this paper, we propose a novel evolutionary algorithm called Genetic Algorithm with Asexual Reproduction (GAwAR) to solve Maximum Lifetime Coverage (MLC) Problem in Wireless Sensor Networks (WSN). We use for GAwAR a binary coding of the problem, develop asexual operator of crossover and operator of mutation in which knowledge about MLC problem is incorporated, and apply deterministic selection. We compare the proposed algorithm with a standard Genetic Algorithm with elitist strategy. We show that the proposed GAwAR significantly outperforms the standard Genetic Algorithm.

This paper deals with optical packet switching in a full-IP transport network scenario. Given the technological limits of accomplishing packet buffering in the optical domain, deflection routing is here explored as an alternative technique for resolving packet contentions without buffering packets. Two different network topologies have been considered here, that is a regular six-node network with different connectivity factors and the classical NSF network. A limited amount of optical buffering is considered in the switching nodes that performs both input queuing and shared queuing of packets to be switched. The performance improvements that can be obtained by deflection routing have been evaluated considering different methods for choosing the alternative paths where to deflect packets that cannot be transmitted onto the shortest path to the addressed destination.

Inter-Autonomous System (AS) links represent nowadays the real bottleneck of the Internet. Internet carriers may coordinate to efficiently balance the load, but the current practice is often based on an uncoordinated selfish routing. Firstly, we assess this issue by characterizing BGP route deviations across top-tier interconnections we could detect using recent Internet routing history data. Then, in order to improve the current practice, we present a novel gametheoretical framework to efficiently coordinate the routing on inter-AS links while modeling the non-cooperative carrier behavior. It relies on a coordinated use of the Multi-Exit Discriminator (MED) attribute of BGP, hence it is nick-A preliminary version of this paper has been published in the 2009 Next Generation Internet Networks (NGI 2009) conference proceedings (best paper award) .

Redundant data retransmission problem in wireless sensor networks (WSNs) can be eliminated using the data aggregation process which combines similar data to reduce the resource-consumption and consequently, saves energy during data transmission. In the recent days, many researchers have focused on securing this paradigm despite the constraints it imposes such as the limited resources. Most of the solutions proposed to secure the data aggregation process in WSNs are essentially based on the use of encryption keys to protect data during their transmission in the network. Indeed, the key generation and distribution mechanisms involve additional computation costs and consume more of energy. Considering this, in this paper, we propose a new security mechanism to secure data aggregation in WSNs called SDAW (secure data aggregation watermarking-based B Djallel Eddine Boubiche

Wireless body area networks (WBANs) have seen an increase in popularity in recent years. Electromagnetic waves created by the body have the capacity to connect nodes all over the epidermis and throughout the body. If the gadget does not cause discomfort or harm, it can be linked to or implanted in the body. This is something that is currently being worked on. Other factors influence an individual's genuine mobility and the ease with which they can use something. Participating in social networks may enhance the lives of members. WBANs equipped with sensors can monitor a user's heart rate and communicate that information to the user's physician. WBAN has been shown to be a dependable electronic health solution. WBAN technology allows you to follow your patient's data no matter where they are, when they are, or what they are doing. However, because it runs in an open Wi-Fi environment and can conceal users' physiological data, it is more vulnerable to assault. To deal with resource-constrained WBAN sensors and devices, a cryptographic solution that is both very efficient and extremely secure is required. Our primary priority will be the safeguarding of the WBAN network. WBAN contains several significant security weaknesses that must be addressed immediately. WBANs might benefit from certificateless signature encryption that uses a hyperelliptic curve and works over a secure channel. We are outpaced by the opposition by 4.58 milliseconds.

Vehicular Ad-hoc NETworks (VANETs) is a special form of Mobile Ad-hoc NETworks (MANETs). The continuous developments in wireless networks have paved the way for the adoption of wireless data exchange for onroad vehicles. The application of VANETs is considered as a key component within the envisioned Intelligent Transportation Systems (ITS). One of the primary applications of VANETs is to enhance the safety measures for the vehicles on-road. Information about vehicles, such as vehicle speed and location coordinates are passed among vehicles to improve their awareness of each other. In VANETs, vehicles are referred to as nodes within a network where each node can act as both; end devise and router. The current design of VANETs has been identified with several drawbacks, while obtaining high performance in multi-hop message dissemination being as one of the most prominent issues. This problem need a solution to improve VANET's performance, especially over networks with high node densities. In this paper, we propose an ontologybased approach for multi-hop message dissemination over VANETs as a solution that would address the above highlighted issue.

Cloud computing is an emerging market place in which computing resources are treated as the utilities and priced for their usage. A huge competition prevails among the cloud Service Providers (SPs) to offer eco-friendly and economically viable cloud services. Heterogeneous Cluster System (HCS) forms the backbone of such computing resources and for eco-friendly services, minimal energy consumption in HCS is a challenging issue. It not only brings down the operational cost but enhance the system reliability and other environmental veneration as well. Commonly, a green Service Level Agreement (SLA) is made between cloud users and SP. Green SLA ensures that a certain percentage of of the schedule is sacrificed for an energy efficient schedule. This work proposes a scheduling framework to execute heterogeneous independent jobs on a HCS. It also introduces a SLA based negotiation scheme for makespan, energy and cost reffered as "Makespan, Energy and Cost Negotiator (MECN)". The proposed model utilizes all possible empty slacks of the schedule running on Processing Elements (PEs) and extended (due to SLA). Using Dynamic Voltage and Frequency Scaling (DVFS) technique, it provides an energy efficient schedule. A resource replacement strategy is also incorporated, in the proposed framework, to generate a cost effective schedule without sacrificing its performance. The performance of the model is analyzed by its simulation which reflects its usefulness and effectiveness.

Prior laboratory studies have shown that PhishGuru, an embedded training system, is an effective way to teach users to identify phishing scams. PhishGuru users are sent simulated phishing attacks and trained after they fall for the attacks. In this current study, we extend the PhishGuru methodology to train users about spear phishing and test it in a real world setting with employees of a Portuguese company. Our results demonstrate that the findings of PhishGuru laboratory studies do indeed hold up in a real world deployment. Specifically, the results from the field study showed that a large percentage of people who clicked on links in simulated emails proceeded to give some form of personal information to fake phishing websites, and that participants who received PhishGuru training were significantly less likely to fall for subsequent simulated phishing attacks one week later. This paper also presents some additional new findings. First, people trained with spear phishing training material did not make better decisions in identifying spear phishing emails compared to people trained with generic training material. Second, we observed that PhishGuru training could be effective in training other people in the organization who did not receive training messages directly from the system. Third, we also observed that employees in technical jobs were not different from employees with non-technical jobs in identifying phishing emails before and after the training. We conclude with some lessons that we learned in conducting the real world study.

There exist a lot of methods for vision through an opaque medium. At present UWB (Ultra-Wideband) technology is used more and more because it is suitable for localization and detection of a human body behind a wall. First of all this paper describes known methods for vision through walls, which can be divided into two general groups -imaging and non-imaging systems. Secondly it describes the state of the art UWB radar for this application and its specifics. Finally it depicts our UWB radar system (centre frequency 4,7GHz) and our practical procedures relevant to the detection of a human body presented behind a concrete wall.

In this paper, we present a comprehensive taxonomy of the most popular authentication mechanisms, the main threats, vulnerabilities, the possible types of attacks and the security issues that are associated with computer systems. Our main contribution is to analyze the architecture of the current security environment from all aspects and to make a comparative assessment of different authentication methods in order to identify and develop a scalable and reliable mechanism that must deal with multi-level security and strong authentication requirements. We propose hybrid methods of authentication, which combine and integrate biometric technologies with cryptographic asymmetric algorithms, elements that play a vital role in the field of information security and aim to resolve the shortcomings of traditional methods of authentication and enhance the level of security.

Over a decade, cryptographers are more attentive on designing lightweight ciphers in focus to compact cryptographic devices. More often, the security of these algorithms are defined in terms of its resistance to mathematical cryptanalysis methods. Nevertheless, designers are well aware of implementation attacks and concentrating on new design strategies to improve the defence quality against implementation attack. PRINCE [3] and RECTANGLE [17] lightweight block ciphers are designed using new design strategies for efficiency and security. In this paper we analyse the security of PRINCE and RECTANGLE against a type of implementation attack called Differential Power Analysis (DPA) attack. Our attack reduces key search space from 2 128 to 33008 for PRINCE and 2 80 to 288 for RECTANGLE.

A VANET is type of MANET that allows vehicles to communicate with roadside equipment. The vehicles may not have a direct Internet connection the wireless roadside equipment may be connected to the Internet that allows data from the vehicles to be sent over the Internet. In Ad-hoc vehicular scenario the dedicated short size communication frequency. The Wave protocol which does not provide sufficient spectrum for reliable exchange of safety message to overcome this problem cognitive network architecture is implemented to extend the control channel CCH used by vehicles to transfer safety massages to achieve this cooperative spectrum sensing scheme through which the network vehicle can optimize the available spectrum resource on that bandwidth. The CCH detect the vacant frequency and use them for transmission of safety message.

An optimal cooperation strategy, decode-tocooperate, is proposed and investigated for performance improvements in dual-hop wireless relay networks. Based on decode-and-forward (DF) strategy with multiple relay selection, we design a novel scheme such that the source node keeps transmitting sequentially and the selected relays cooperate by transmitting the decoded signal using distributed Alamouti coding. We exploit the multipath propagation effect of the wireless channel to achieve lower probability of error and introduce optimum power allocation and relay positioning. We analyze the scenario when the source to destination direct link is not available and derive a closed form expression for symbol error rate (SER), its upper bound and an asymptotically tight approximation to exploit the performance gain by selecting the optimum relays in a multiple-relay cooperation scheme. Moreover, asymptotic optimum power allocation (based on the SER approximation) and optimal relay positioning are also considered to further improve the SER. The proposed relay selection scheme outperforms cooperative (DF) and non-cooperative schemes by more than 2 dB.

Effective emergency management of a disaster at a single point of failure is vital if the effects of the disaster are to be mitigated. The immediate impacts of a disaster highlight stakeholder perspectives. There is no one-size-fits-all solution to every disaster. Nevertheless, analysing features, aftermath, impact and interim services made available after a disaster provide lessons that can be utilised to avert or mitigate the effects of similar events in the future. This paper provides lessons learnt from the a fire that occurred in 2012 in the Warrnambool telephone exchange located in Victoria, Australia and proposes a strategy that provides increased network resilience and more effective emergency management once the copper-based core switching in exchanges is progressively replaced by fibre service area modules.

A new optically controlled reconfigurable antenna for cognitive radio is presented. The antenna can operate at an ultra-wideband and three narrow bands by controlling four photoconductive switches. The bandwidth of the ultra-wideband is 2.65 to 10.3 GHz. The bandwidths of three narrow bands are 7.10 to 8.01 GHZ, 3.55 to 5.18 GHz, and 5.12 to 6.59 GHz, respectively.

The behavior of IP based network traffic has been the subject of several works. In this paper we compare two modeling approaches and their ability to capture two basic traffic features: packet size distribution and interarrival times. Data traces have been measured at the border gateway of the campus network of the University of Pavia at different times of the day. The two modeling schemes use respectively well established Hidden Markov Model (HMM) techniques and a stochastic engine derived from chaotic attractors.

Law on Electronic Communications and its additional rules should provide conditions for Internet access and using the Internet services, by the principles of transparency and non discrimination, and these conditions determines the operator with significant market power in relevant markets. Also, it lays down the rules applicable for the distribution of limited resources. Using of Internet Services takes great momentum and growth, and the users of telecommunications services are increasingly use the Internet services, and in that way shall take into consideration the technical resources for using of Internet services and adapt to the needs and accept the offered quality. The Government of the Republic of Macedonia has taken a special efforts on accelerate the liberalization process, with special emphasis on using the Internet services and the aggressive introduction competition in all telecommunications segments, including Internet services, because it is a prerequisite for the creation called inclusive Information Society which creates the preconditions for reducing the existing monopoly on particular market, and rapid increasing in the economy and also in the market competition field, improvement of social and cultural cohesion, reduction of the costs for doing activity in the fields of Internet services, and also accomplishes the principle goal behind the general policy of the Government, which includes the liberalization of the Internet service market, no matter of the technical part of the transmission, and to the utilization of benefits that globalization brings, and certainly stimulated the Internet services and their growth in the Republic of Macedonia and to take its place on the world map, in the economy, as well as in the IT roadmap. This electronic document is a "live" template and already defines the components of your paper [title, text, heads, etc.] in its style sheet.

A novel framework for the analysis and optimization of cognitive wireless networks with unslotted time operations and reactive primary users is proposed. In the considered network setting, primary users' channel access is regulated by a carrier sense-based contention mechanism. As the sensing mechanism cannot distinguish between primary and secondary signals, secondary users' activity may interfere with primary users' channel contention, thus biasing the statistics of the stochastic process modeling primary users' transmissions. In fact, a primary user which wakes up during a transmission from a secondary user may sense a busy channel and enter backoff or generate a collision. The proposed framework considers these effects and optimizes the fraction of time a secondary user is allowed to transmit according to a constraint on the minimum throughput achieved by the primary users. Numerical results are presented which illustrate fundamental behaviors and tradeoffs in a network with one primary and one secondary user. Extension to more general scenarios is also discussed.

In this paper we compare two traffic models based on Markov modulated Poisson processes (MMPPs), that were designed to capture self-similar behavior over multiple time scales. These models are both constructed by fitting the distribution of packet counts in a number of time scales. The first model is a superposition of MMPPs where each MMPP describes a different time scale. The second one is obtained as the equivalent to an hierarchical construction process that, starting at the coarsest time scale, successively decomposes MMPP states into new MMPPs to incorporate the characteristics offered by finner time scales. We evaluate the accuracy of the models by comparing the probability mass function at each time scale, as well as the loss probability and average waiting time in queue, corresponding to measured traces and to traces synthesized according to the proposed models. The analysis is based on three measured traffic traces exhibiting self-similar behavior: the well-known pOct Bellcore trace and two traces measured in a Portuguese ISP. Based on the obtained results, we conclude that both Markovian models have good and very similar performances in matching the characteristics of the data traces over the relevant time scales. However, one advantage of the hierarchical approach is that the number of states of the corresponding MMPP can be much smaller.

For reducing the energy consumption of the Mobile Station in mobile Broadband Wireless Access networks, IEEE 802.16 offers three kinds of sleep mode operations called power saving classes type I, type II and type III. In order to investigate mathematically the inherent relationships between the performance measures and the system parameters, we propose in this paper a novel method for modeling the sleep mode with the power saving class type II in IEEE 802.16 and analyzing the performance of this sleep mode. Considering the attractive feature that some data frames can be transmitted during the listening state, we present a queueing model with two kinds of busy mechanisms to capture the working principle of the sleep mode operations with the power saving class type II. With the first and higher derivatives of the probability generating functions, we can give the averages and the standard deviations for the system performance using the diffusion approximation for the operating process of the system. We also propose methods for measuring the system performance in terms of the switching ratio, the energy saving ratio, and the average response time of data frames, as well as giving the expressions for these performance measures. Numerical results are provided with analysis and simulation to show the average performance measures, standard deviations and the cost function with different system loads. Moreover, we construct a cost function with the aim of determining the optimal time length of the sleep window to minimize the cost function.

An ultra-wideband planar four-element multiple-input multiple-output (MIMO) antenna array for millimeter wave (mmWave) 5G applications is presented in this article, characterized by a simple structure and diverse performance capabilities. The antenna system operates in the 20 GHz band (ranging from 42.3 to 63.3 GHz), with a high gain of 7.8 dB. The compact size of 25 × 25 mm makes it suitable for being integrated with various telecommunication devices used in a number of mmWave applications. The antenna's elements are placed orthogonally, achieving great isolation of over 24 dB. The performance of the proposed antenna was analyzed in terms of its s parameters, gain, efficiency, radiation patterns, and MIMO diversity characteristics, including the envelope correlation coefficient (ECC), diversity gain (DG), and mean effective gain (MEG).

Most work on Differentiated Services (DiffServ) handles Quality of Service (QoS) provisioning on a per node basis, which assumes that this strategy would provide QoS in the entire domain. Nevertheless, this approach could fail in large domains with multiple flow aggregation and unexpected input traffic. Therefore, provisioning techniques should be used to avoid unexpected overloads that result in QoS fluctuations. A proposal using fuzzy controllers to reconfigure DiffServ nodes according to both incoming traffic and the actual QoS is given. However, it is not easy to specify fuzzy rule bases and membership functions that optimize controller performance. Thus, we also propose a methodology to choose fuzzy controller parameters using the Wang-Mendel and genetic algorithms. Finally, we evaluate the performance of this model by simulation of an IP Telephony application in a DiffServ domain.

The authors report measurement of the radio-frequency (RF) transport electromagnetic properties of chemical vapour deposition graphene over the direct current (DC) to 110 MHz frequency range at room temperature. Graphene on Si/SiO 2 substrate was mounted in a shielded four terminal-pair (4TP) adaptor which enabled direct connection to a calibrated precision impedance analyser for measurements. Good agreement is observed for the DC four-probe resistance and the 4TP resistance at 40 Hz, both yielding R ≈ 104 Ω. In general, the apparent graphene channel electromagnetic properties are found to be strongly influenced by the substrate parasitic capacitance and resistance, particularly for high-frequencies f > 1 MHz. A phenomenological lumped-parameter equivalent circuit model is presented which matches the frequency response of the graphene 4TP impedance device over approximately seven decades of the frequency range of the applied transport alternating current. Based on this model, it is shown for the first time, that the intrinsic graphene channel resistance of the 4TP device is 'frequency-independent' with R G ≃ 105 Ω or sheet resistance of approximately 182 Ω/□. The parasitic substrate impedance of the device is found to be R P ≃ 2.2 Ω and C P ≃ 600 pF. These results suggest that our new RF 4TP method is in good agreement with the conventional DC four-probe method for measuring the intrinsic sheet resistance of single-atom thick materials and could potentially open up new applications in RF electronics, AC quantum Hall effect metrology and sensors based on graphene 4TP devices operating over a broad range of frequencies.

We report on the challenges faced in the implementation and simulation of a side-channel communication based on frames with an intentionally corrupted Frame Check Sequence (FCS). Systematically corrupted FCSs can be used to enable covert communications between nodes that share the same algorithm for deciphering the FCS. In order to assess the possibility in detecting this side-channel communication it is necessary to have the ability to simulate it as well as to implement it on actual devices. Nearly all simulators drop corrupted frames before they reach their destination, making it impossible to simulate any side-channel communication based on intentionally corrupted FCS. We present an example of the modifications required to prevent this as applied to a well-known simulator called Sinalgo. We also discuss problems encountered when trying to intentionally corrupt the FCS on actual devices.