Network Simulator

Next generation networks will combine various access technologies to enable users to roam freely from one access network to another which is referred as Vertical handovers. Vertical handovers mobility management in next generation all-IP networks is the key factor that determines vertical handovers (HO) performance. Mobility management is generally based on mobility protocols that perform the handovers either horizontally (within the same access network) or vertically (between different access technologies). In this context, many solutions were proposed to provide seamless vertical handovers between WLAN and WiMax networks. These solutions aimed to perform the HO with minimum QoS degradation based on either the coupling architecture method, the mobility management protocol or the handover decision process. Our solution is based on the handover decision process that will make use of the emerging WiMax technology in order to guide the vertical handover to the suitable destination netw...

The evolutionary algorithm AMALGAM implements the novel concept of adaptive multimethod search to ensure a fast, reliable and computationally efficient solution to multiobjective optimization problems. The method finds a well-distributed set of Pareto solutions within a single optimization run, and achieves an excellent performance compared to commonly used methods such as SPEA2, NSGA-II and MOEA/D. In this paper, I review the basic elements of AMALGAM, provide a pseudo-code of the algorithm, and introduce a MATLAB toolbox which provides scientists and engineers with an arsenal of options and utilities to solve multiobjective optimization problems involving (among others) multimodality, high-dimensionality, bounded parameter spaces, dynamic simulation models, and distributed multi-core computation. The AMALGAM toolbox supports parallel computing to permit inference of CPU-intensive system models, and provides convergence diagnostics and graphical output. Four different case studies are used to illustrate the main capabilities and functionalities of the AMALGAM toolbox.

Abstract: In Fixed Wireless Applications (FWA), the Code Division Multiple Access (CDMA) is the most promising candidate for wideband data access. The reason is the soft limit on the number of active mobile devices. Many Fixed Wireless Applications impose an upper bound on the BER performance which restricts the increase in number of mobile users. The number of active mobile users or Capacity is further reduced in Multipath Fading Environment (MFE). This paper presents an effective method of improving the capacity of CDMA based Fixed ...

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.

Quantum computing is a form of unconventional computation utilizing quantum effects as a fundamental part of its calculations. It has already been used in practical signal encryption in the 2010 Soccer World Cup, and there is competition amongst many governments to build more powerful and practical quantum computers. Although quantum computing is the most widespread and invested in form of unconventional computation, there have been no implementations of artistic systems with live hardware quantum computers. Furthermore there is a vast gap between public understanding of classical digital computing and of quantum computing. Q-Muse is a quantum computer music system design for a specific performance. The Entangled Orchestra is a performance for Orchestra, Electronics and Live Internet-Connected Photonic Quantum Computer. There are many types of quantum computation hardware implementations including Nuclear Magnetic Resonance, Trapped Ions, and Optical Computing. Q-Muse incorporates t...

Transmission Control Protocol (TCP) is known to suffer from performance degradation in mobile wireless environments, as such environments are prone to packet losses due to high bit error rates and mobility induced disconnections, because TCP is well reliable protocol for wired networks. In wired network packet loss due to congestion. Proposed scheme is a true end-to-end approach, based on the idea of exclusive handover message and is used for alleviating the degrading effect of host mobility on TCP performance. Experiments are performed using the Network Simulator (NS-2). The simulator has been extended to incorporate wireless link characteristics.

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Modern digital infrastructure confronts escalating cyber threats while conventional processing systems demonstrate inadequate performance in addressing real-time security challenges across enterprise networks. Brain-inspired computational frameworks offer revolutionary alternatives by mimicking biological neural mechanisms to overcome fundamental limitations present in traditional cybersecurity architectures. Temporal spike-based processing networks deliver biologically authentic methods for examining time-dependent characteristics within data transmission flows, facilitating enhanced recognition of coordinated service disruption attacks, persistent infiltration campaigns, and irregular network behaviors. Activity-triggered computational models substantially minimize energy consumption while preserving microsecond response capabilities crucial for protecting organizational network assets. Fusion with access governance protocols strengthens identity verification procedures and permission management through simultaneous evaluation of diverse communication channels. Large-scale neural processing hardware exhibits remarkable computational performance with processing elements functioning at elevated operational frequencies while maintaining reduced power utilization levels. Timingdependent synaptic adaptation enables continuous learning functionality, permitting automatic calibration of detection variables according to changing network environments. Power conservation benefits prove especially significant for extensive installations where electrical consumption directly influences operating expenses and ecological responsibility. Deployment obstacles encompass equipment procurement limitations, architectural compatibility issues, and coordination requirements with established technological infrastructure. Anticipated developments include protocol unification projects, enhanced machine learning techniques, and thorough assessment platforms designed to expedite progression from conceptual designs to functional cybersecurity implementations.

An atomic source of single photons in the telecom band 1 CHRISTOPHER PHENICIE, ALAN DIBOS, MOUKTIK RAHA, JEFF THOMP-SON, Princeton University -Single atoms are ideal sources of single photons and long-lived memories for quantum networks. However, most atomic transitions are in ultraviolet-visible wavelengths, where propagation losses in optical fibers prohibit long distance transmission. A notable exception is the Er 3+ ion, whose 1.5 µm transition is exploited in fiber amplifiers that drive telecommunication networks. However, an optical interface to single Er 3+ ions has not yet been achieved because of the low photon emission rate (<100Hz). Recently, we have observed the emission of single photons from a single Er 3+ ion in a solid-state host [1]. This was enabled by interfacing Er 3+ ions with silicon nanophotonic cavities, which enhances the photon emission rate by a factor of more than 300. Dozens of distinct ions can be addressed in a single device based on inhomogeneous variations in their transition frequencies. We will also discuss ongoing progress on characterizing the spin dynamics of this system, spin-photon entanglement, and interactions between nearby Er 3+ defects. These results are a significant step towards long-distance quantum networks and deterministic quantum logic for photons based on a scalable silicon nanophotonics architecture. [1] Dibos, A.M. et al, arxiv: 1711.10368 1 EFRI ACQUIRE program (grant 1640959). C. M. P. is supported by a NDSEG fellowship

A mass deployment of femtocells is anticipated to affect a number of areas more adversely, especially in the celledge of the macrocell network. In this paper, we propose a flexible frequency-partitioning scheme for OFDMA network based on cyclic difference sets. The cyclic property of these sets allows a quick construction of orthogonal patterns for the macrocell and femtocell networks with an emphasis on tri-sector sites. The impact and the co-deployment of femtocells is also investigated. Unlike, with existing works in the literature, the novel scheme can adaptively control the level of coverage in the cell-edges areas and additionally enables coexistence of femtocells in the network. Simulation results confirm the effectiveness of the proposed scheme in both macrocell and femtocell networks compared to the legacy soft frequency reuse and universal frequency reuse.

Mobility of nodes is an important issue in mobile adhoc networks (MANET). Nodes in MANET move from one network to another individually and in the form of group. In single node mobility scheme every node performs registration individually in new MANET whereas in group mobility scheme only one node in a group i.e group representative (GR) performs registration on behalf of all other nodes in the group and is assigned Care of Address (CoA). Internet protocol (IP) of all other nodes in the group remains same. Our simulated results prove that group mobility scheme reduces number of messages and consumes less time for registration of nodes as compared to single node mobility scheme. Thus network load is reduced in group mobility scheme. This research paper evaluates the performance of group mobility with single node mobility scheme. Test bed for this evaluation is based on Network Simulator 2 (NS-2) environment.

A typical Internet protocol (IP)could not address the mobility of nodes and was only designed for fixed networks where the nodes were improbable to move from one location to other. An ever-increasing dependence on network computation makes the use of portable and handy devices,inevitable. Mobile IP protocol architecture was developed tomeet such needs and support mobility. Mobile IPlets the roving nodes to establish an uninterrupted connection towards internet without altering the IP address whilemoving to another network.However, Mobile IP goes through several issues like ingress filtering, triangle routing, handoff and Quality of service problems etc. In this paper we discuss few of those with their possible solutions. That resolves these problems, reduce the unnecessary load from the network and enhance the efficiency. Some security threats on mobile and their solutions are also focused to secure the communicationduring mobility.

The mass composition and all-particle energy spectrum of cosmic rays are determined by analysis of coincident events between the IceTop air shower array on the surface and the deep IceCube strings. IceTop mainly detects the electromagnetic component of high energy cosmic ray air showers, while the TeV muon bundle penetrates deep into the Antarctic ice and generates Cherenkov light, which is seen by IceCube. This analysis uses data taken from June 2010 to May 2011 when the detector was nearly complete with IceCube in its 79 string conguration and IceTop running 73 stations. Variables sensitive to composition and primary energy are based on the lateral signal distribution reconstructed at the surface by IceTop and the energy loss of the muon bundles reconstructed by IceCube. Using a neural network we determine the average mass A and all-particle flux in the energy range from a few PeV up to 1 EeV. We find that < log A > increases up to at least 100 PeV.

The combined information from cosmic ray air showers that trigger both the surface and underground parts of the IceCube Neutrino Observatory allows the reconstruction of both the energy and mass of the primary particle through the knee region of the energy spectrum and above. The properties of high-energy muon bundles, created early in the formation of extensive air showers and capable of penetrating deep into the ice, are related to the primary energy and composition. New methods for reconstructing the direction and composition-sensitive properties of muon bundles are shown. Based on a likelihood minimization procedure using IceCube signals, and accounting for photon propagation, ice properties, and the energy loss processes of muons in ice, the muon bundle energy loss is reconstructed. The results of the highenergy muon bundle reconstruction in the deep ice and the reconstruction of the lateral distribution of low energy particles in the surface detector can be combined to study primary composition and energy. The performance and composition sensitivity for both simulated and experimental data are discussed.

muon bundle, simple and more advanced reconstructions are used. The existing reconstructions I improved and new reconstructions I developed are explained in Chapter 4. High quality reconstruction are obtained by performing advanced hit cleaning algorithms on the detected signals before reconstructions and by removing low quality events. These methods are described in Chapter 5 and result in a high quality selection of data with reconstructed variables that are sensitive to primary mass and primary energy. The extraction of the primary mass and primary energy is done by a combination of a neural network approach, followed by a template fitting to extract the average mass for each reconstructed energy. The technical details of these analysis tools are explained in Chapter 6. Before the final energy spectrum and composition measurement is discussed in Chapter 8, I will first give an overview about the systematic uncertainties in this analysis in Chapter 7.

The pervasiveness and the seemingly unpopular nature of unidirectional data transfer has greatly necessitated the efforts of this paper. We investigated the performance of User Datagram Protocol (UDP) over IP-based wireline and wireless networks. The conceptual model was developed and tested using Network Simulator 2(NS2) and its bevaviour was monitored over the two networks. The results of the simulation in terms of effective throughput, packet drop/loss, and bandwidth utilization were presented. It reveals that UDP exhibits improved performance degradation on wired networks and that the high throughput is as a result of the fact that UDP does not have flow control protocol as it does not retransmit lost packets.

Existing priority-based QoS routing protocols in ad hoc wireless networks did not consider the effect of mutual interference between routes in wireless medium during routing. We have investigated the effect of mutual interference on the routing performance in wireless environment and explored the advantage of using zone-disjoint routes to avoid mutual interference and to improve the network performance. In this paper, a priority based QoS routing scheme is proposed that uses the notion of zone-disjoint routes. Our protocol avoids the contention between high and low priority routes by reserving high priority zone of communication. Low priority flows will try to avoid this zone by selecting routes that is maximally zonedisjoint with respect to the high priority reserved zone and will consequently allow a contention-free transmission of high priority traffic in that reserved zone. If, under some unavoidable situations, a low priority flow has to go through high priority reserved zone causing interference then it will block itself temporarily to allow contention-free transmission of high priority flows and later may resume the blocked communication if possible. We have evaluated the effectiveness of our proposed protocol on QualNet network simulator.

The use of directional antenna in wireless ad hoc networks largely reduces radio interference, thereby improving the utilization of wireless medium and consequently the network throughput, as compared to omnidirectional antenna, where nodes in the vicinity of communication are kept silent. In this context, researchers usually assume that the gain of directional antennas is equal to the gain of corresponding omni-directional antenna. However, for a given amount of input power, the range R with directional antenna will be much larger than that using omni-directional antenna. In this paper, we propose a two-level transmit power control mechanism in order to approximately equalize the transmission range R of an antenna operating at omnidirectional and directional mode. This will not only improve medium utilization but also help to conserve the power of the transmitting node during directional transmission. The performance evaluation on QualNet network simulator clearly indicates the efficiency of our protocol.

Application of multipath routing techniques in mobile ad hoc networks has been explored earlier, as multipath routing may help to reduce end-to-end delay, perform load balancing and consequently improve throughput. However, it has also been shown that the success of multipath routing in ad hoc wireless network depends on network topology and channel characteristics can severely limit the gain offered

Mobile Ad Hoc Networks (MANET) have emerged as one of the most significant areas of research in the field of mobile computing. However, the dynamics of mobile, wireless ad hoc networks as a consequence of mobility and disconnection of mobile hosts pose a number of problems in designing proper routing schemes for effective communication between any source and destination. The protocols proposed so far in this context and mechanisms for data communication have failed to ensure a stable QoS in such an infrastructure primarily due to two main reasons. First, due to the dynamism of the ad hoc architecture, uninterrupted multimedia (or any other data) communication has to rely heavily on the changing link stability. And, second, on link failures, resuming communication requires the entire route-establishment process to be redone. This generates intolerable overhead and delay. In this paper, we address the problem of maintaining a stable route in a resource limited, dynamic architecture li...

A fundamental problem that distinguishes wireless networks from wired networks is the mutual interference between routes within the proximity of each other. This phenomenon is known as route coupling and it restricts the possibility of occurrence of simultaneous communications along the coupled routes. In this context, the use of directional antenna, having smaller transmission beam‐width compared to omni‐directional antenna, helps to easily decouple interfering routes, and improves network performance through space division multiple access (SDMA). However, even if we have an efficient directional MAC protocol, it alone would not be able to guarantee good system performance, unless we have a proper routing strategy in place that exploits the advantages of directional antenna. So, in this paper, an adaptive routing strategy is proposed that exploits the advantages of directional antenna in ad hoc networks through the selection of maximally zone‐disjoint shortest routes. Zone‐disjoint...

In hippocampal slices, high-frequency (125-333 Hz) synchronized oscillations have been shown to occur amongst populations of pyramidal neurons, in a manner that is independent of chemical synaptic transmission, but which is dependent upon gap junctions. At the intracellular level, highfrequency oscillations are associated with full-sized action potentials and with fast prepotentials. Using simulations of two pyramidal neurons, we previously argued that the submillisecond synchrony, and the rapid time-course of fast prepotentials, could be explained, in principle, if the requisite gap junctions were located between pyramidal cell axons. Here, we use network simulations (3072 pyramidal cells) to explore further the hypothesis that gap junctions occur between axons and could explain high-frequency oscillations. We show that, in randomly connected networks with an average of two gap junctions per cell, or less, synchronized network bursts can arise without chemical synapses, with frequencies in the experimentally observed range (spectral peaks 125-182 Hz). These bursts are associated with fast prepotentials (or partial spikes and spikelets) as observed in physiological recordings. The critical assumptions we must make for the oscillations to occur are: (i) there is a background of ectopic axonal spikes, which can occur at low frequency (one event per 25 s per axon); (ii) the gap junction resistance is small enough that a spike in one axon can induce a spike in the coupled axon at short latency (in the model, a resistance of 273 MV works, with an associated latency of 0.25 ms). We predict that axoaxonal gap junctions, in combination with recurrent excitatory synapses, can induce the occurrence of high-frequency population spikes superimposed on epileptiform field potentials. ᭧ 1999 IBRO. Published by Elsevier Science Ltd.

Mobility of nodes is an important issue in mobile adhoc networks (MANET). Nodes in MANET move from one network to another individually and in the form of group. In single node mobility scheme every node performs registration individually in new MANET whereas in group mobility scheme only one node in a group i.e group representative (GR) performs registration on behalf of all other nodes in the group and is assigned Care of Address (CoA). Internet protocol (IP) of all other nodes in the group remains same. Our simulated results prove that group mobility scheme reduces number of messages and consumes less time for registration of nodes as compared to single node mobility scheme. Thus network load is reduced in group mobility scheme. This research paper evaluates the performance of group mobility with single node mobility scheme. Test bed for this evaluation is based on Network Simulator 2 (NS-2) environment.

This paper presents an analytical and simulationbased work which helps to estimate time duration of routes in a mobile ad-hoc network. First, we studied a simple route with a single intermediate node between source and destination, and then we model how long it takes for the intermediate node to leave the route (i.e., leave the overlapping region formed by the intersection of the coverage areas between source and destination). Then, we generalized the model for routes with N intermediate nodes. Simulation experiments were developed using the NS-2 network simulator to verify that our theoretical model agrees with simulation results.

This paper presents the design, analysis and performance evaluation of VRing, a novel application-layer multicast (ALM) protocol that establishes a virtual ring as an overlay network among the multicast group members in a selforganizing and distributed manner. VRing takes advantage of the inherent desirable property of a ring; namely, the degree of each node on the ring is O´1µ (i.e., independent of the number of the group members) and hence, the state maintained at each group member is also O´1µ. In order to reduce the routing delay of the ring overlay network, we propose to form a spare ring overlay structure that improves connectivity among group members. The design of the spare ring is justified by proposing, and analytically studying the performance of, a data delivery and duplicate suppression mechanism that makes use of both the original ring and the spare ring for forwarding data packets. We conduct simulations of both VRing and a hierarchical ALM protocol, NICE, using the J-Sim network simulator. Simulation results show that although VRing has a higher path stretch and a higher link stress than NICE, it provides less control overhead, consumes less bandwidth, and provides lower average node degree than NICE. Furthermore, VRing achieves a higher average data delivery ratio in the presence of failures than NICE. The performance improvement is especially pronounced for larger multicast groups.

Due to recent expansion of wireless communications, it has become impossible to cope with the allotment of the precious spectrum while resources for wireless communication are bounded and finite. Hence, the cognitive radio concept is introduced to ensure optimal utilization of these invaluable resources. By emerging research in the field of cognitive radio network, fresh researchers are looking for a suitable simulator for the cognitive radio network since the implementation and testbed is not practical and feasible invariably. Moreover, there is no simulator that has been designed with cognitive radio networks in mind. Furthermore, this research area is relatively new. Therefore, often it becomes very hard to decide which network simulator to work with, as the availability of reference is significantly low. As a result, much effort is required to make a proper decision. In this paper, we take a detailed look at current simulators used by researchers in the field of cognitive radio networks to help researchers identify appropriate tools for simulation. To further aid researchers, we classify the simulation tools, demonstrate their architectures, describe features, elucidate advantages and disadvantages of these tools, and report some open issues and challenges for future research.

This paper studies first-best and second-best congestion pricing in the presence of unobserved and observed preference heterogeneity using a stylised stochastic user equilibrium choice model. Travellers choose between multiple alternatives, have heterogeneous values of travel times, and may differ in their valuation of variety. We derive first-best and second-best tolls taking into account how the overall network demand responds to expected generalized prices, including tolls. For second-best pricing, we show that with homogeneous values of times the welfare losses of second-best pricing are smaller when route choice is probabilistic than when route choice is deterministic. Furthermore, we find that with heterogeneous values of times and benefits of variety, uniform second-best tolls and group-differentiated tolls can be very close, implying potentially low welfare losses from the inability to differentiate tolls. Finally, we show that there are cases where all groups benefit from second-best congestion pricing, but that these cases are likely to be politically unacceptable because tolls are then higher for low income groups.

A description of ongoing work which aims to provide better quality propagation models for use in network simulators is provided in this paper. A 3D ray-tracing model is described which allows for accurate specification of a variety of wave scattering phenomena. Details of its parallelisation are given as well as a discussion of future work including the incorporation of a visibility algorithm. Results illustrate the increased realism obtained by using site-specific propagation models.

Simulation has been of paramount importance to the development of novel Internet protocols. Such an approach typically focuses on one of three domains: wireless and other link-layer technologies, routing protocols, and transport-layer mechanisms and protocols. Existing techniques can tackle well simulation at layers 2, 3 and 4 of the TCP/IP architecture, but are not flexible enough to appropriately deal with application-layer protocols. These require simulators that support the modeling of networks and components with different levels of abstraction. Simmcast is an object-oriented framework that focuses on the necessary flexibility for application-layer protocol research. A simulation can be developed by the simple extension of building blocks that closely resemble components of a real network such as hosts, links and routers. The internal complexity of these components, however, is hidden from the user, so he/she can focus on the implementation of the desired protocol characteristics. This paper describes the flexible simulation architecture proposed and instantiated through Simmcast, and draws lessons from our experience in designing, implementing and deploying it. We also present framework instances used to evaluate application-layer protocols, exemplifying how different kinds of simulations can be developed with Simmcast.

Most VANET simulators do not allow for feedback between the vehicle mobility model and the network simulator. This limits the realistic simulation of safety and traffic information applications that might cause drivers to change their routes. To address this issue, we developed extensions to the SWANS wireless network simulator. Our SWANS modules, which we collectively call ASH (Application-aware SWANS with Highway mobility), make several contributions. ASH allows for the needed two-way communication between the mobility model and the networking model. To support highway scenarios, we built in ASH a customizable highway topology, allowing entrances, exits, and variable number of lanes. ASH includes implementations of the existing IDM car-following and MOBIL lane-changing models, as well as the Inter-Vehicle Geocast data dissemination protocol. To facilitate diverse simulations, ASH enhances the node model in SWANS to allow for the presence of non-participating vehicles and obstacles, along with participating vehicles and road-side infrastructure. These additions to the scalable SWANS simulator will allow for realistic VANET simulations of important safety and traffic information applications.

The quantum internet represents a paradigm shift in communication technology by utilizing the fundamental principles of quantum mechanics such as superposition, entanglement, and quantum teleportation. Unlike classical networks, the quantum internet promises unconditionally secure communication, distributed quantum computing, clock synchronization, and enhanced sensing. This paper provides a comprehensive review of the quantum internet's architecture, including physical, link, network, and application layers. It also explores enabling protocols like quantum key distribution, entanglement swapping, and quantum error correction. Special emphasis is placed on India's strategic initiatives, such as the National Quantum Mission (NQM), and its growing role in global quantum research and infrastructure development. The paper concludes by outlining technological challenges, scalability issues, and a roadmap for future deployment.

At the transport layer of the Open System Interconnection (OSI) model, the transmission control protocol (TCP) is a major protocol used in today's communication over the Internet. The TCP is designed to provide a reliable end-to-end connection over unreliable links. Besides affecting the physical and media access control (MAC) layers of the OSI model, ensuring the high data rates in environments characterised with fluctuations in the quality of the wired links or wireless channels deteriorate the performance of the transport layer of the network . Ensuring reliable end-to-end connections over versatile wired and wireless networks which become complex and heterogeneous, presents a demanding challenge in terms of its practical implementation. This challenge arose during the last decades as the subject of the researchers' interest . One of the mechanisms that plays a critical role in TCP performance is the congestion control (CC) mechanism. One of the main purposes of the CC mechanism is to probe the network for available capacity by dynamically increasing or decreasing the amount of data (also known as window size) that can be sent over a communication link. This approach enables avoiding the congestion of the network that can be caused by a large burst of data during transmission . Node or link congestion in wired networks and blockage and beam misalignment in wireless networks can seriously affect the TCP CC mechanism. This further results in poor end-to-end transmission performance. Conventional TCP CC algorithms are not able to differentiate between the potential causes of packet loss. They can occur due to a lack of wired link capacity or poor wireless channel quality . In today's data networks, the main protocol used to ensure reliable communications is the transmission control protocol (TCP). The TCP performance is largely determined by the used congestion control (CC) algorithm, which main purpose is to avoid the congestion of the network that can be caused by a large burst of data traffic. TCP CC algorithms have evolved over the past three decades and a large number of CC algorithm variations have been developed to accommodate various communication network environments. Considering the importance of CC in communication networks, the fundamentals of the TCP as the main transport layer protocol and CC process have been explained in detail. Also, an encyclopedic overview of the most popular single-flow and multi-flow TCP CC algorithms with corresponding alternatives has been present. Future directions in the possible improvement of CC algorithms for implementation in complex heterogeneous networks composed of wired and wireless elements are lastly discussed in this encyclopedic work.

The formidable growth of WSN research has opened challenging issues about their performance evaluation. Despite the steady increase in mathematical analysis and experimental deployments, most of the community has chosen simulation for their study. Although it seems straightforward, this approach becomes a quite delicate matter. Complexity is caused by several issues. First, the large number of nodes heavily impacts simulation performance and scalability. Second, credible results demand an accurate characterization of the sensor radio channel. New aspects, inherent in WSN, must be included in simulators, e.g. a physical environment and an energy model, leading to different degrees of accuracy versus performance. Moreover, many necessary models are in the continuous-time domain (e.g. heat transmission, battery discharge), being complex to integrate into discrete event network simulators. These issues result in an exponential growth of the overall network state information. Through this survey we review these problems both quantitatively and qualitatively while depicting a common suitable simulation model. We also briefly describe the most significant simulation frameworks available.

In this work we have devoted to some proposed analytical methods to simulate these attacks, and node mobility in MANET. The model used to simulate the malicious nodes mobility attacks is based on graphical theory, which is a tool for analyzing the behavior of nodes. The model used to simulate the Blackhole cooperative, Blackmail, Bandwidth Saturation and Overflow attacks is based on malicious nodes and the number of hops. We conducted a simulation of the attacks with a C implementation of the proposed mathematical models.

This research paper clearly identifies the problems of data transmission traffic, erratically slow data and video streaming on the World Wide Web internet through the network interface cards (NICs). It also provides the reliable solutions and appropriate means to address these perennial problems of ICT-Based institutions and organisations. The entire wired or wireless internet data network connectivity of an institution is sustained by the standard of installed Network Interface Cards (NICs). The standard and the relative performance metrics of NIC types such as 1Gbps, 10Gbps and 100Gbps were adequately examined using different information data sizes of 20MB, 40MB, 60MB, 80MB and 100MB which is either meant for data upload or download on the internet network. Specifically, the paper categorically discusses the parameters for performance metrics of each of these Ethernet card which include the data transmission time, data total time delay and throughput. The research work accurately established the active features of the NICs as the major backbone of the Internet network and the transmission control protocol (TCP) which is designed for reliable transmission of data over the internet. TCP as a connectionless protocol of the NIC is majorly used for surfing webs, downloading and uploading files. In practical terms, the TCP is able to dynamically adapt its packet sending rate to the network conditions in order to achieve the highest possible throughput. In a nutshell , this research paper proposes an upgrade to 100Gbps Ethernet card on the Internet infrastructures of ICT-Based institutions in order to ensure reliable, efficient, sustainable, fast and effective internet data access in all internet devices connected to their networks.

Smart Antenna Systems (SAS) are providing a strong increasing impact in digital wireless communication systems. Due to their great advantages regarding nodes power saving and coverage enhancing, SAS are largely employed on pervasive network environments such as MANET. Because almost the whole of existing network simulators use omnidirectional antennas on nodes, we propose a new version of Inet framework of Omnet++ that extends its operation also for network scenarios in which nodes are equipped with directional antennas. Furthermore, we created a new directional antenna module that simulates the behaviour of a Phased Array System and a very simple algorithm for power management in channel. The new proposed model presents some modifications to key-modules that are involved in a normal wireless communication scenario, in order to support asymmetrical communications between nodes.

In cellular network, channels are scarce radio resources. These resources are to be utilized judiciously. Though efforts have been made in the past for maximum channel utilization, studies show that effective channel utilization is often not done because of various constraints. The cognitive radio concept suggests that opportunistic channel utilization is possible if the mobile services are classified into two classes. The usage of the channels are based on the cognition that the radio derives. This work proposes a new model that applies a meta-heuristic Genetic Algorithm and the concept of cognitive radio for better channel utilization. The concept of single channel and multi-channel lending is also introduced towards this. Priority is given to the handoff services in comparison to the new services. The performance study, of the model, suggest the effective channel utilization in terms of blocked and dropped services.

In a multi-hop mobile ad hoc network (MANET), mobile nodes cooperate to form a network without using any infrastructure such as access points or base stations. The mobility of the nodes and the fundamentally limited capacity of the wireless medium, together with wireless transmission effects such as attenuation, multi-path propagation, and interference combine to create significant challenges for security in MANETs. Traditional cryptographic mechanisms such as authentication and encryption are not capable of handling some kinds of attacks such as packet dropping by malicious nodes in MANETs. This paper presents a mechanism for detecting malicious packet dropping attacks in MANETs. The mechanism is depends on a trust module on each node, which is based on the reputation value computed for that node by its neighbors. The reputation value of a node is computed based on its packet forwarding behavior in the network. The reputation information is gathered, stored and exchanged between the nodes, and computed under different scenario. The proposed protocol has been simulated in a network simulator. The simulation results show the efficiency of its performance.

Wireless Sensor Networks (WSNs) are highly distributed networks consisting of a large number of tiny, lowcost, light-weight wireless nodes deployed to monitor an environment or a system. Each node in a WSN consists of three subsystems: the sensor subsystem which senses the environment, the processing subsystem which performs local computations on the sensed data, and the communication subsystem which is responsible for message exchange with neighboring sensor nodes. While an individual sensor node has limited sensing region, processing power, and energy, networking a large number of sensor nodes give rise to a robust, reliable, and accurate sensor network covering a wide region. Thus, routing in WSNs is a very important issue. This paper presents a query-based routing protocol for a WSN that provides different levels of Quality of Service (QoS): energy-efficiency, reliability, low latency and fault-tolerance-under different application scenarios. The algorithm has low computational complexity but can dynamically guarantee different QoS support depending on the requirement of the applications. The novelty of the proposed algorithm is its ability to provide multiple QoS support without reconfiguration and redeployment of the sensor nodes. The algorithm is implemented in network simulator ns-2 and its performance has been evaluated. The results show that the algorithm is more efficient than some of the currently existing routing algorithms for WSNs.

With an annual passenger capacity of more than 4 billion and a rapidly increasing number, air transport is the undisputed leader among other travel options for long-distance traveling. There are unique airline connections between more than 20 thousand cities in the world. Despite this, many passengers fly via connecting as there are no direct flights from many cities to many cities or because direct flights are sometimes not economical or common. Since passengers do not like to wait in transfers, passengers are lost to other flights and airline companies if the airline does not have a suitable flight at the appropriate time for the transfer. Arrival and departure synchronization is vital at major hub airports and major airlines. In this study, the synchronization of arrival and departure flights is solved for Istanbul airport, an important hub airport worldwide, using data from a prominent airline company. Three metaheuristic methods, Evolutionary Strategies (ES), Modified Discrete Particle Swarm Optimization (MDPSO), and Random Search (RS) were used, and the results were compared with the original plan (OP). ES and MDPSO were found to be promising solution methods, and they provided substantially increased acquired passengers during connecting flights.

Intraplatoon information management strategies for dealing with safe and stable operation are proposed in this paper. New algorithms to mitigate communication delays are presented, and Matlab/Simulink-based simulation results are reported. We argue that using anticipatory information from both the platoon's leader and the followers significantly impacts platoon string stability. The obtained simulation results suggest that the effects of communication delays may be almost completely canceled out. The platoon presents a very stable behavior, even when subjected to strong acceleration patterns. When the communication channel is subjected to a strong load, proper algorithms may be selected, lowering network load and maintaining string stability. Upon emergency occurrences, the platoon's timely response may be ensured by dynamically increasing the weight of the platoons' leaders data over the behavior of their followers. The simulation results suggest that the algorithms are robust under several demanding scenarios. To assess if current intervehicle communication technology can cope with the proposed information-updating schemes, research into its operation was conducted through a network simulator.

Garden City University is a higher learning institution in Ghana, in the second capital, Kumasi. The institution has several faculties and departments. The communication requirement of the institution has changed over years after establishment, ranging from traditional communication delivery using office messengers to the use of mixed mode where they still deliver messages through messengers or call using GSM/telephone networks, which is usually costly as compared to other available methods. Voice over internet protocol is a prevailing technology that can enhance an organizations communication. Asterisk PBX is a software based private business exchange that has the capability to outsmart a traditional analogue PBX system. This research project therefore uses the power vested in the open source asterisk PBX to deploy a prototype of a communication system for Garden city university college, using open source liblinphone library and Software development kit to create a softphone for both inbound and outbound communication among staff and the university administration. The system uses Raspberry pi for the prototype. The same project can be replicated on a powerful computer architecture for relatively higher capacity of communication. Evaluation of the system is done to ascertain information about the project. The evaluation of the prototype helps in building similar system for production use. A GSM modem with voice support is later used to interface the Asterisk PBX network with public switch telephone network so that staff could dial regular telephone numbers.

The deployment of wireless ad hoc networks faces severe limitations by mutual interference between wireless devices. In this work, we introduce a method to alleviate interference using a medium access control (MAC) layer exploiting multiuser detection (MUD). Instead of interference avoidance, the primary task of such a MAC layer is interference handling. To this end, we first identify link layer requirements for deploying MUD in a decentralized and self-organizing network. Based on these requirements, we propose a MAC protocol supporting MUD. We estimate possible throughput gains of this protocol. Network simulations confirm the analytical results and show remarkable throughput improvements.

Evaluating the performance of distributed applications, such as mobile telephone or video conferencing devices, has become increasingly complex as the diversity of scenarios and data rates in networks increase. In this paper, we present the design and implementation of RplTrc, a network emulation tool. RplTrc uses traces to drive interceptions of the Linux protocol stack to delay, drop or duplicate packets. The length of traces is not limited. Thus, unlike other well-known emulators such as NIST Net or the emulator module in the Linux 2.6 kernel, RplTrc is capable to account for important performance characteristics inherent to real networks such as long-range dependence and selfsimilarity of cross-traffic. Tests show that RplTrc installed on a commodity PC is capable to emulate a 100MBit/s or a lightlyloaded 1GBit/s network and has a precision in reproducing packet delays in the order of 100 µs. RplTrc thus enables extensive performance evaluation of distributed applications in lab environments.

To deal with the "memory wall" problem, microprocessors include large secondary on-chip caches. But as these caches enlarge, they originate a new latency gap between them and fast L1 caches (inter-cache latency gap). Recently, Non-Uniform Cache Architectures (NUCAs) have been proposed to sustain the size growth trend of secondary caches that is threatened by wire-delay problems. NUCAs are size-oriented, and they were not conceived to close the inter-cache latency gap. To tackle this problem, we propose Light NUCAs (L-NUCAs) leveraging on-chip wire density to interconnect small tiles through specialized networks, which convey packets with distributed and dynamic routing. Our design reduces the tile delay (cache access plus one-hop routing) to a single processor cycle and places cache lines at a finer-granularity than conventional caches reducing cache latency. Our evaluations show that in general, L-NUCA improves simultaneously performance, energy, and area when integrated into both conventional or D-NUCA hierarchies.

In this paper, a model of self-organizing spiking neural networks is introduced and applied to mobile robot environment representation and path planning problem. A network of spike-response-model neurons with a recurrent architecture is used to create robot-s internal representation from surrounding environment. The overall activity of network simulates a self-organizing system with unsupervised learning. A modified A* algorithm is used to find the best path using this internal representation between starting and goal points. This method can be used with good performance for both known and unknown environments.

This paper investigates the feature negotiation procedure of the Datagram Congestion Control Protocol (DCCP) in RFC 4340 using Coloured Petri Nets (CPNs). After obtaining a formal executable CPN model of DCCP feature negotiation, we analyse it using state space analysis. The experimental result reveals that simultaneous negotiation could be broken on even a simple lossless FIFO channel. In the undesired terminal states, the confirmed feature values of Client and Server do not match.

The semi-annual alternation between polar day and polar night causes the South Pole atmosphere to undergo a large annual change. Seasonal changes of the atmosphere highly affect the properties of cosmic ray air showers. IceCube detects the high-energy muonic component of air showers with the 1 km 3 underground detector, whereas IceTop, the surface array, mainly measures the electromagnetic component. The influence due to the seasonal changes on the high-energy muon multiplicity, important for composition studies, is studied in simulation and data. To reduce this variation, a correction procedure based on the measured atmospheric temperature profile and the muon production longitudinal profile is proposed.