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The increasing interest on spectrum resources causes various efforts on developing smart and compact solutions as joint radar-communication (JRC) systems. A JRC system can offer cost-effective solution with concurrent operation, as target sensing via radar processing and establishing communication links. JRC capability has been proposed over the years for different types of MIMO radars. However, a JRC capable monostatic coherent MIMO radar system is yet to be developed. These radars offer several advantages as fully coherent signal processing and coherent transmit beamforming which provides beampatterns to minimize probability of intercept. In this paper, two new waveform generation techniques suitable for JRC operation without disturbing transmit beamforming requirements and waveform orthogonality condition in space and time domain are proposed for monostatic coherent MIMO radars. Then, new communication methods are introduced for phase coded monostatic coherent MIMO radars. First method uses chirp-wise information encoding inside the radar pulse as intra-pulse communications. Second rotates the phase of a specific waveform on radiated symbols to a specific direction and the last method applies a small amount of progressive phase shift to the radar waveforms emitted from the antennas to create relative phase modulation between selected radar waveforms. Then, the performance of the proposed communication techniques are investigated in terms of bit error rate (BER) and generated waveforms are examined according to the orthogonality and transmit beamforming requirements., NA

High throughput capability of the terahertz band (0.3-10 THz) wireless communications is expected to be utilized by the fifth generation of mobile telecommunication systems and enable a plethora of new applications. Supporting devices will transfer large amounts of data in both directions, causing high energy consumption by the electronic circuitries of the equipment in use. Therefore, physical layer for these systems must be designed carefully in order to reduce energy consumption per bit. In this paper, the best performing modulation scheme and hardware parameters that minimize the energy consumption without affecting the system throughput are determined. THz band device technologies are outlined and a complete survey of the state-of-the-art low-THz band circuit blocks which are suitable for mass market production is given. It is shown that for short-range communications, M-ary quadrature amplitude modulation is the most energy-efficient technique that can lead up to 90% reduction in consumed energy. Moreover, optimal transceiver parameters which can be used to further minimize the energy consumption of the THz band system are examined., Scientific and Technological Research Council of Turkey (TÜBİTAK)

Fog Computing is a new paradigm that has been proposed by CISCO to take full advantage of the ever growing computational capacity of the near-user or edge devices (e.g., wireless gateways and sensors). The paradigm proposes an architecture that enables the devices to host functionality of various user-centric services. While the prospects of Fog Computing promise numerous advantages, development of Fog Services remains under-investigated. This article considers an opportunity of Fog implementation for Alert Services on top of Wireless Sensor Network (WSN) technology. In particular, we focus on targeted WSN-alert delivery based on spontaneous interaction between a WSN and hand-held devices of its users. For the alert delivery, we propose a Gravity Routing concept that prioritizes the areas of high user-presence within the network. Based on the concept, we develop a routing protocol, namely the Gradient Gravity Routing (GGR) that combines targeted delivery and resilience to potential sensor-load heterogeneity within the network. The protocol has been compared against a set of state-of-the-art solutions via a series of simulations. The evaluation has shown the ability of GGR to match the performance of the compared solutions in terms of alert delivery ratio, while minimizing the overall energy consumption of the network.

Recently, huge attention is attracted to the concept of integrating communication and radar missions within the same platform. Joint Radar-Communications (JRC) system gives an important opportunity to reduce spectrum usage and product cost while doing concurrent operation, as target sensing via radar processing and establishing communication links. A JRC-capable coherent MIMO radar system have been proposed recently in the literature. Several methods are introduced to reach dual goal as a notable null level towards the direction of interest of the radar and MIMO radar waveform orthogonality. Due to the limitations originated form the JRC operation, communication channel may encounter unwanted amplitude variations. This unwanted modulation normally affects the communication performance by its nature, due to the fades on radiated signal amplitude towards the direction of communication. However, the effect of this unintentional modulation on communication channel is yet to be investigated. In this paper, the communication channel for JRC capable phase-coded coherent MIMO radars is analyzed and investigated under additive white Gaussian noise and Rayleigh/Rician fading conditions. Communication capacity is evaluated for each channel condition. The results reveal that, using the single-side limited null direction fixed waveform generation method displays the best capacity performance under all channel conditions., NA

In a natural disaster such as an earthquake, it is vital to know the number of people trapped under the ruins. To address this problem, we propose RESCUE - wiREless backScattering CommUnication based disastEr recovery system. RESCUE is composed of special Radio-frequency identification (RFID) readers and sensors that are used to determine the total number of people under the ruins. Passive wireless sensor nodes are placed inside the building during construction and are equipped with a camera that is activated during an earthquake. After the earthquake, communication to the passive tags of sensors is achieved by wireless power transfer from a reader located outside the ruins. Tags harvest this energy and send the image data stored by the camera. We also design an antenna structure to maximize simultaneous wireless information and power transfer (SWIPT) for devices under ruins. We analyze the communication channel between reader and sensors and derive a channel model over ruins. Furthermore, we obtain the results of experimental study where we validate the derived channel model. Results show that RESCUE can collect the desired data in a relatively short time, and hence, is a promising disaster recovery system architecture., Scientific and Technological Research Council of Turkey (TÜBİTAK); Turkish National Academy of Sciences Distinguished Young Scientist Award Program (Turkish Academy of Sciences (TÜBA)-GEBIP)

© 2017 Elsevier B.V. Due to the opportunistically resource usage of users in cognitive radio sensor networks (CRSNs), the availability of network resources is highly variable. Therefore, admission control is an essential mechanism to manage the traffic of cognitive radio users in order to satisfy the quality of service (QoS) requirements of applications. In this study, a connection admission control (CAC) mechanism is introduced to satisfy the requirements of delay sensitivity and power consumption awareness. This proposed mechanism is modeled through a semi Markov decision process (SMDP) and a linear programming problem is derived with the aim of obtaining the optimal policy to control the traffic of CRSNs and achieving maximum reward. The number of required channels at each network state is estimated through a graph coloring approach. An end to end delay constraint is defined for the optimization problem which is inspired from Kleinrock independence approximation. Furthermore, a power-aware weighting method is proposed for this mechanism. We conduct different simulation-based scenarios to investigate the performance of the proposed mechanism. The experimental results demonstrate the efficiency of this SMDP-based mechanism in comparison to the last CAC mechanism in CRSNs.

Performance guarantees for congestion control schemes in cognitive radio sensor networks (CRSNs) can be helpful in order to satisfy the quality of service (QoS) in different applications. Because of the high dynamicity of available bandwidth and network resources in CRSNs, it is more effective to use the stochastic guarantees. In this paper, the stochastic backlog and delay bounds of generic rate-based additive increase and multiplicative decrease (AIMD) congestion control scheme are modeled based on stochastic network calculus (SNC). Particularly, the probabilistic bounds are modeled through moment generating function (MGF)-based SNC with regard to the sending rate distribution of CR source sensors. The proposed stochastic bounds are verified through NS2-based simulations., Iran Telecommunication Research Center (ITRC)

Given the highly variable physical layer characteristics in cognitive radio sensor networks (CRSN), it is indispensable to provide the performance analysis for cognitive radio users for smooth operations of the higher layer protocols. Taking into account the dynamic spectrum access, this paper formulates the two fundamental performance metrics in CRSN; bandwidth and delay. The performance is analyzed for a CSMA-based medium access control protocol that uses a common control channel for secondary users (SUs) to negotiate the wideband data traffic channel. The two performance metrics are derived based on the fact that SUs can exploit the cognitive radio to simultaneously access distinct traffic channels in the common interference region. This feature has not been exploited in previous studies in estimating the achievable throughput and delay in cognitive radio networks. Performance analysis reveals that dedicating a common control channel for SUs enhances their aggregated bandwidth approximately five times through the possibility of concurrent transmissions on different traffic channels and reduces the packet delay significantly. (C) 2013 Elsevier B.V. All rights reserved.

This paper presents measurements and statistical characterization to compare three potential bands of the low-THz channel, namely, the 300 to 319 GHz, 340 to 359 GHz and 380 to 399 GHz bands. From the large set of measurements performed in line-of-sight (LoS) and non-LoS (NLoS) environments, parameters for path loss model with shadowing are evaluated. Our results show that the path loss exponents for the band around 310 GHz, 350 GHz, and 390 GHz is 2.07, 1.90 and 1.96, respectively. The impacts of different materials acting as surfaces in LoS channels and reflectors in NLoS environments are also examined. Additionally, the statistical analysis due to temporal, spatial and multipath propagation is performed to determine the best fit distributions. Finally, we look at some networking scenarios in THz Band communication to derive the expressions for the number of connections a user can make based on antenna characteristics, data rate requirements and antenna mobility as well as network density. Our results suggest fundamental parameters that can be used in future THz Band analysis with applications in both macro and micro scale Internet of Things (IoT)., Scientific and Technological Research Council of Turkey (TÜBİTAK)

In this paper, we develop a realistic model of the synaptic multiple-input single-output (MISO) communication channel for cortical neurons. The synaptic channel weights change adaptively according to the rules of spike timing-dependent plasticity (STDP) to enable learning and memory within neuronal connections. We calculate the ergodic capacity of the synaptic multiple-input multiple-output (MIMO) communication channel, and investigate its performance using the statistical properties of neuro-spike communication. Moreover, we analyze the communication performance of synaptic channels in terms of decoding error probability, and define a lower bound on the synaptic multiple-input single-output (MISO) communication channel.

To realize molecular nanonetworks, the foundations of molecular information theory should be established through identification of the existing molecular communication mechanisms, and architectures and networking techniques for nanomachines should be developed, which demand novel engineering efforts. Luckily, these engineering skills and technology have been prepared for us by the natural evolution in the last several billions of years. Indeed, the human body is a massive nanoscale molecular communications network as it is composed of billions of interacting nanomachines, i.e., cells. Intra-body biological systems are closely linked to each other and communicate primarily through molecular transactions. Thus, vital activities inside the human body are regulated by everlasting communication performance and operations of intra-body molecular nanonetworks. However, natural intra-body molecular nanonetworks are yet to be explored with the elegant tools of information and communication theories. In this paper, first, the elementary models for significant intra-body molecular communication channels, i.e., nanoscale neuro-spike communication channel, action potential-based cardiomyocyte molecular communication channel, and hormonal molecular communication channel, are introduced. Next, molecular nanonetworks belonging to multi-terminal extensions of channel models, i.e., nervous, cardiovascular molecular, and endocrine nanonetworks are discussed. Furthermore, heterogeneous communication network of intra-body molecular nanonetworks together with five senses, i.e., nanosensory networks, is explored from the perspectives of communication and network theories. Moreover, open research challenges, such as extension of molecular channel models to multi-terminal cases, and developing a communication theory perspective to understand the physiology and to capture potential communication failures of intra-body biological systems, are provided. Our objectives are to learn from the elegant molecular communication mechanisms inside us for engineering practical communication techniques for emerging nanonetworks, as well as to pave the way for the advancement of revolutionary diagnosis and treatment techniques inspired from information and communication technologies, which is promising for future nanomedicine and bio-inspired molecular communication applications.

Communication requirements for cognitive radio sensor networks (CRSN) necessitate addressing the problems posed by dynamic spectrum access (DSA) in an inherently resource-constrained sensor networks regime. In this paper, arising challenges for reliability and congestion control due to incorporation of cognitive radio capability into sensor networks are investigated along with the open research issues. Impact of DSA, i.e., activity of licensed users, intermittent spectrum sensing and spectrum handoff functionalities based on spectrum availability, on the performance of the existing transport protocols are inspected. The objective of this paper is to point out the urgent need for a novel reliability and congestion control mechanism for CRSN. To this end. CRSN challenges for transport layer are revealed and simulation experiments are performed to demonstrate the performance of the existing transport protocols in CRSN., Scientific and Technological Research Council of Turkey (TÜBİTAK); Turkish National Academy of Sciences (Turkish Academy of Sciences (TÜBA)-GEBIP)

A number of nanomachines that cooperatively communicate and share molecular information in order to achieve specific tasks is envisioned as a nanonetwork. Due to the size and capabilities of nanomachines, the traditional communication paradigms cannot be used for nanonetworks in which network nodes may be composed of just several atoms or molecules and scale on the orders of few nanometers. Instead, molecular communication is a promising solution approach for the nanoscale communication paradigm. However, molecular communication must be thoroughly investigated to realize nanoscale communication and nanonetworks for many envisioned applications such as nanoscale body area networks, and nanoscale molecular computers. In this paper, a simulation framework (NanoNS) for molecular nanonetworks is presented. The objective of the framework is to provide a simulation tool in order to create a better understanding of nanonetworks and facilitate the development of new communication techniques and the validation of theoretical results. The NanoNS framework is built on top of core components of a widely used network simulator (ns-2). It incorporates the simulation modules for various nanoscale communication paradigms based on a diffusive molecular communication channel. The details of NanoNS are discussed and some functional scenarios are defined to validate NanoNS. In addition to this, the numerical analyses of these functional scenarios and their experimental results are presented. The validation of NanoNS is shown via comparative evaluation of these experimental and numerical results.

The developments in the communication and networking technologies have yielded many existing and envisioned information network architectures such as cognitive radio networks, sensor and actor networks, quantum communication networks, terrestrial next generation Internet, and InterPlaNetary Internet. However, there exist many common significant challenges to be addressed for the practical realization of these current and envisioned networking paradigms such as the increased complexity with large scale networks, their dynamic nature, resource constraints, heterogeneous architectures, absence or impracticality of centralized control and infrastructure, need for survivability, and unattended resolution of potential failures. These challenges have been successfully dealt with by Nature, which, as a result of millions of years of evolution, have yielded many biological systems and processes with intrinsic appealing characteristics such as adaptivity to varying environmental conditions, inherent resiliency to failures and damages, successful and collaborative operation on the basis of a limited set of rules and with global intelligence which is larger than superposition of individuals, self-organization, survivability, and evolvability. Inspired by these characteristics, many researchers are currently engaged in developing innovative design paradigms to address the networking challenges of existing and envisioned information systems. In this paper, the current state-of-the-art in bio-inspired networking is captured. The existing bio-inspired networking and communication protocols and algorithms devised by looking at biology as a source of inspiration, and by mimicking the laws and dynamics governing these systems are presented along with open research issues for the bio-inspired networking. Furthermore, the domain of bio-inspired networking is linked to the emerging research domain of nanonetworks, which bring a set of unique challenges. The objective of this survey is to provide better understanding of the potentials for bio-inspired networking which is currently far from being fully recognized, and to motivate the research community to further explore this timely and exciting topic.

Molecular communication enables nanomachines to exchange information with each other by emitting molecules to their surrounding environment. Molecular nanonetworks are envisioned as a number of nanomachines that are deployed in an environment to share specific molecular information such as odor, flavor, or any chemical state. In this paper, using the stochastic model of molecular reactions in biochemical systems, a realistic channel model is first introduced for molecular communication. Then, based on the realistic channel model, we introduce a deterministic capacity expression for point-to-point, broadcast, and multiple-access molecular channels. We also investigate information flow capacity in a molecular nanonetwork for the realization of efficient communication and networking techniques for frontier nanonetwork applications. The results reveal that molecular point-to-point, broadcast, and multiple-access channels are feasible with a satisfactorily high molecular communication rate, which allows molecular information flow in nanonetworks. Furthermore, the derived molecular channel model with input-dependent noise term also reveals that unlike a traditional Gaussian communication channel, achievable capacity is affected by both lower and upper bounds of the channel input in molecular communication channels.

Wireless Sensor and Actor Networks (WSAN) are composed of large number of sensor nodes collaboratively observing a physical phenomenon and relatively smaller number of actor nodes, which act upon the sensed phenomenon. Due to the limited capacity of shared wireless medium and memory restrictions of the sensor nodes, channel contention and network congestion can be experienced during the operation of the network. In fact, the multi-hop nature of WSAN entangles the level of local contention and the experienced network congestion. Therefore, the unique characteristics of WSAN necessitate a comprehensive analysis of the network congestion and contention under various network conditions. In this paper, we comprehensively investigate the interactions between contention resolution and congestion control mechanisms as well as the physical layer effects in WSAN. An extensive set of simulations are performed in order to quantify the impacts of several network parameters on the overall network performance. The results of our analysis reveal that the interdependency between network parameters call for adaptive cross-layer mechanisms for efficient data delivery in WSAN.

The existing TCP protocols contribute to the stability of the Internet by deploying window-based additive-increase multiplicative-decrease (AIMD) congestion control. However, the window-based congestion control is not favorable in the existence of long propagation delay and for real-time multimedia traffic. Thus, the rate-based congestion control has become an attractive alternative for the links with high delay and for multimedia flows. In this paper, an analysis of the rate-based generic AIMD congestion control scheme is presented. The analytical model is validated Via simulation experiments for a wide range of link conditions and the effects of rate-increase and decrease parameters on the performance are investigated. One important result of this analysis is that throughput performance of the rate-based schemes is inversely proportional to square-root of the propagation delay whereas that of the window-based schemes is known to be inversely proportional to the propagation delay itself. This result also justifies that the rate-based congestion control schemes have higher resilience to the high link delay than the window-based schemes.

The developments in the space technologies are enabling the realization of deep space scientific missions such as Mars exploration. InterPlaNetary (IPN) Internet is expected to be the next step in the design and development of deep space networks as the Internet of the deep space planetary networks. However, there exist significant challenges to be addressed for the realization of this objective. Many researchers and several international organizations are currently engaged in defining and addressing these challenges and developing the required technologies for the realization of the InterPlaNetary Internet. In this paper, the current status of the research efforts to realize the InterPlaNetary Internet objective is captured. The communication architecture is presented, and the challenges posed by the several aspects of the InterPlaNetary Internet are introduced. The existing algorithms and protocols developed for each layer and the other related work are explored, and their shortcomings are pointed out along with the open research issues for the realization of the InterPlaNetary Internet. The objective of this survey is to motivate the researchers around the world to tackle these challenging problems and help to realize the InterPlaNetary Internet.

Keywords: lts4 Reference EPFL-ARTICLE-131247doi:10.1016/j.comnet.2008.06.011View record in Web of Science Record created on 2009-01-19, modified on 2017-05-10