Overlay Protocol Research Articles

Outage and throughput performance analysis of smart UAV‐assisted full‐duplex NOMA‐based energy harvesting cognitive radio networks

SummaryIn this paper, the throughput and outage performance for an unmanned aerial vehicle (UAV)‐assisted non‐orthogonal multiple access (NOMA)‐based hybrid cognitive radio (CR) network are examined under m‐Nakagami fading channel. To be more specific, a secondary source transmitter ( ) broadcasts a NOMA‐enabled mixed signal to secondary destinations via UAV relay, which operates in full‐duplex (FD) mode and employs decode‐and‐forward protocol. In our approach, an energy harvesting (EH) circuit is employed at both and UAV to harvest energy from the PU radio frequency (RF) signals. These secondary transmitters are also incorporated with energy detector (ED) circuit as well, which detects the activity of the primary user (PU). The status of PU to be busy or idle is confirmed on the basis of the energy detector's results. In turn, this drives and UAV to switch between underlay and overlay protocols in an adaptive manner to increase spectrum efficiency (SE). The closed form mathematical expressions of the secondary outage probability for NOMA‐based UAV equipped CR networks under imperfect successive interference cancellation (i‐SIC) conditions have been evaluated. The administration of the power allocation policy at the and UAV is assessed while maintaining the PU quality of service (QoS). Finally, MATLAB simulation testbed has been used to verify all the analytical closed form expressions.

CPA-MAC: A Collision Prediction and Avoidance MAC for Safety Message Dissemination in MEC-Assisted VANETs

Vehicular ad hoc networks (VANETs) have been widely recognized as a promising solution to improve traffic safety and efficiency for the ability to provide situation awareness even though the potential dangers and traffic anomalies are out of the visual range. In VANETs, time-division multiple access (TDMA) based overlay protocols can prevent transmission collisions and play an important role in providing an efficient communication channel. However, due to high vehicle mobility and time-varying traffic flow, the existing TDMA-based slot allocation approaches cannot fully utilize the channel resources, resulting in high transmission delay and packet collision. To overcome these shortcomings, we propose a collision prediction and avoidance MAC (CPA-MAC) protocol that utilizes the capability of mobile edge computing (MEC) and machine learning in this paper. Specifically, we propose a new slot assignment method that aims to guarantee the high channel utilization and low delay of safety message under dynamic traffic conditions. Furthermore, we propose a new same-direction collisions prediction algorithm that combines the V2R communication and LSTM-based trajectory prediction algorithm. Finally, we conduct extensive experiments to demonstrate the effectiveness of the proposed protocol.

The HOP Protocol: Reliable Latency-Bounded End-to-End Multipath Communication

Next-generation wireless networks are expected to enable new applications with strict latency constraints. However, existing transport layer protocols are unable to meet the stringent Quality of Service (QoS) requirements on throughput and maximum latency: excessive queuing due to capacity-oriented congestion control inflates end-to-end latency well beyond interactivity deadlines. In this work, we propose a novel framework that evolves best-effort communications into reliability- and latency-aware communications for QoS-sensitive applications. The new protocol, named High-reliability latency-bounded Overlay Protocol (HOP), provides a novel combination of packet-level Forward Error Correction (FEC) and multipath scheduling to compensate for capacity drops and meet pre-defined QoS requirements. More specifically, the sender splits the data and the associated redundancy between the paths by using a stochastic forecast of their future capacity and decides the amount of redundancy necessary to meet the application’s requirements without clogging the connections. We compare HOP’s performance with state-of-the-art multipath protocols in ns-3 simulations using both synthetic and live network traces, and confirm that our scheme can reliably deliver high-throughput data, reducing the number of late blocks by 2 to 5 times with respect to optimized Multipath TCP (MPTCP).

A three-dimensional clustered peer-to-peer overlay protocol for mobile ad hoc networks

Peer-to-peer (P2P) computing involves exchanging resources and files by computers connected through a network rather than a central server. In P2P, over mobile ad hoc networks (MANETs), the fundamental necessity is the linkage of the overlay participating peers (OPPs) for the efficient operation of the DHT-based P2P overlay protocol over MANETs. This necessity becomes more critical in a high mobility environment. Due to the high mobility of OPPs, the topology of the P2P overlay is altered continuously. Consequently, the efficiency of DHT-based P2P overlay protocol over MANETs greatly decreases due to the increased lookup latency, maintenance, computational, and control overheads. In the current research, a novel three-dimensional clustered overlay P2P protocol, i.e., 3DCOP, is suggested to cope with the identified issues. Simulation results depict that 3DCOP performs better in routing overhead, false-negative ratio, path-stretch ratio, and file discovery delay in the high mobility environment over MANETs.

Empirical Performance Models of MAC Protocols for Cooperative Platooning Applications

Vehicular ad-hoc networks (VANET) enable vehicles to exchange information on traffic conditions, dynamic status and localization, to enhance road safety and transportation efficiency. A typical VANET application is platooning, which can take advantage of exchanging information on speed, heading and position to allow shorter inter-vehicle distances without compromising safety. However, the platooning performance depends drastically on the quality of the communication channel, which in turn is highly influenced by the medium access control protocol (MAC). Currently, VANETs use the IEEE 802.11p MAC, which follows a carrier sense multiple access with collision avoidance (CSMA/CA) policy that is prone to collisions and degrades significantly with network load. This has led to recent proposals for a time-division multiple access (TDMA)-based MAC that synchronize vehicles’ beacons to prevent or reduce collisions. In this paper, we take CSMA/CA and two TDMA-based overlay protocols, i.e., deployed over CSMA/CA, namely PLEXE-slotted and RA-TDMAp, and carry out extensive simulations with varying platoon sizes, number of occupied lanes and transmit power to deduce empirical models that provide estimates of average number of collisions per second and average busy time ratio. In particular, we show that these estimates can be obtained from observing the number of radio-frequency (RF) neighbours, i.e., number of distinct sources of the packets received by each vehicle per time unit. These estimates can enhance the online adaptation of distributed applications, particularly platooning control, to varying conditions of the communication channel.

РАСПРЕДЕЛЕННАЯ СИСТЕМА СБОРА, ОБРАБОТКИ И АНАЛИЗА СОБЫТИЙ ИНФОРМАЦИОННОЙ БЕЗОПАСНОСТИ СЕТЕВОЙ ИНФРАСТРУКТУРЫ ПРЕДПРИЯТИЯ

The majority of the network infrastructures of government agencies and private enterprises operate on the basis of a TCP/IP protocol stack, which has significant vulnerabilities. For illustrative purposes, it is worth mentioning the lack of verification of the interaction subject authenticity in the basic protocols and technologies of this stack. Some of the TCP/IP stack vulnerabilities can be eliminated by the intelligent functions of managed network devices: from access profiling to traffic segmentation. Complex firewalls, which include intrusion detection and prevention systems, are also an important element of the network protection. Methods of signature, heuristic, behavioral, self-similar, predictable and other approaches for analyzing network traffic and identifying network threats are further being developed by Russian and foreign scientists. However, the proposed solutions do not give an unambiguous result when using overlay technologies and cryptographic protocols. Also, due attention is not being paid to the processing, analysis of network traffic and logs of Windows/Linux operating systems and applications. The aim of this work was the research, development and software implementation of a distributed system for collecting, processing and analyzing security information events of an enterprise network infrastructure. The key task was to ensure objective monitoring of network information security. An additional task was to ensure the monitoring of the activity of users of personal computers running Windows and Linux operating systems. In order to address this challenge, a concept for complex processing of computer network traffic and security information events both on the server and on the client sides was developed. An original signature and statistical method of compiling the knowledge base system by testing and simulating known network and local attacks with tracking the response of operating systems and applications in a virtualization environment is reviewed. The approach to performing the automated analysis of correlating events with the use of deep packets inspection (DPI) and monitoring of users' local activity is described. The reviewed solution was successfully tested and used as one of the modules for providing network information security of the system for intelligent adaptive enterprise network infrastructure management, designed by author.

Proving properties of the Chord protocol using the ASM formalism

This paper describes the overlay protocol Chord using the formalism of Abstract State Machines. The formalization concerns Chord actions that maintain ring topology and manipulate distributed keys. We define a minimal set of deterministic constraints and prove that they guarantee the stability of the topological structure of the network and the consistency of data handling.

Cooperative spectrum sharing in cognitive radio networks: An interference free approach

We present a novel interference free dual-hop cooperative spectrum sharing protocol in cognitive radio networks exploiting spatial modulation (SM) at both primary transmitter (PT) and secondary transmitter (ST). A ST equipped with multi-antenna acts as a half-duplex decode-and-forward relay for the primary system. During phase-1, SM is invoked at PT, while ST keeps silent. The information bit stream of PT is mapped into two different sets: the M-ary phase shift keying (M-PSK)/M-ary quadrature amplitude modulation (M-QAM) bits and the antenna index. The ST then exploits iterative-maximum ratio combining (i-MRC) technique to de-map the block of information bits, transmitted by PT. During phase-2, ST forwards the primary data by activating only one antenna based on its own secondary data exploiting the concept of SM. The PT’s data is then retrieved at the primary receiver (PR) and the secondary receiver (SR) recover its own desired data by detecting only the transmit antenna indices of ST using i-MRC. As a result, mutual interference between primary and secondary systems is avoided and interference cancellation techniques at the PR and SR are no longer needed. In the proposed protocol, the primary user does not need to lease its spectrum or time slots to the secondary user in exchange for cooperation. Moreover, power of ST does not need to be distributed for primary and secondary transmission simultaneously during phase-2. The simulation and analytical results are presented to show effectiveness of the proposed protocol compared to conventional spectrum leasing and superposition coding based overlay protocols.

Reliable Overlay Networking on ETSI GeoNetworking Standards

A position-based routing vehicular ad hoc network (PBR-VANET) is a specific type of mobile ad hoc network where the vehicles are the nodes and the routing is determined on the basis of node positioning. However, PBR-VANET routing protocols suffer from mass packet loss due to frequent changes in topology. We discuss the requirements of the routing protocol and propose an overlay network protocol called Duplicated Unicast Packet Encapsulation (DUPE). The proposed protocol is compatible with the original GeoNetworking standard, and it can cooperate with existing implementations without modifications to either GeoNetworking infrastructures or user applications. It encapsulates a GeoNetworking packet in a BTP packet (a standard Layer 4 protocol in GeoNetworking) and duplicates the original packet into different paths to reduce packet loss caused by failure and outdated paths. The evaluations on DUPE in different scenarios show that, with reasonable latency and bandwidth overhead, the packet loss can be eliminated in certain scenarios, where the standard GeoNetworking protocol has a packet loss of up to 94.5% in the worst case. Real field simulations show that DUPE can improve the packet delivery ratio (PDR) by approximately 20% in real-world deployment.

Characterizing Multihop Aerial Networks of COTS Multirotors

Unmanned aerial vehicles (UAVs) recently enabled a myriad of new applications spanning domains from personal entertainment to surveillance and monitoring. In this paper, we focus on using several small UAVs collaboratively to provide extended reach to an online video monitoring system for inspection of industrial installations. We make use of 802.11 radios on low-cost commercial-off-the-shelf UAVs, set up a time-division multiple access overlay protocol to avoid mutual interference, and enable high channel utilization in multihop networks. In particular, we provide a model for the quality of the UAV-to-UAV link, in terms of packet delivery ratio as a function of distance, packet size, and orientation, based on an extensive measurement campaign. We show that this platform is not omnidirectional in the horizontal plane and that UAV-to-UAV communication ceases around 75 m. Concerning the operation in a multihop mode to allow extending the network, the paper derives the optimal number of hops that maximize the end-to-end throughput, as well as the corresponding hop lengths. We validate our mathematical model with extensive experimental measurements transmitting payloads up to 200 m (over 802.11 g at 54 MBps).

Analysis of Creido Enhanced Chord Overlay Protocol Under Different Movement Models in Delay Tolerant Networks

Delay Tolerant Network (DTN) is an enlivening area to delve in owing to its rudimentary characteristics like intermittent links, variable delays etc. and its physiognomies of applications wherever traditional networks like sparse and emergency mobile ad-hoc networks fails. These applications are aided extensively if the performance metrics are recuperated. In this article a novel plot to increase the end to end bundle delivery ratio by assimilating CREIDO bundles in chord overlay network. This periodic bundle invokes the stabilize function of chord overlay protocol to make the overlay topology robust during node join and exits. In this article, OverSim framework of OMNeT++ is used under different mobility models to analyse the performance metrics of CREIDO bundles. Thus the results obtained were encouraging and outsourced the existing protocol in aspects of Bundle Delivery Ratio and throughput.

Novel insights from 3D models: the pivotal role of physical symmetry in epithelial organization.

3D tissue culture models are utilized to study breast cancer and other pathologies because they better capture the complexity of in vivo tissue architecture compared to 2D models. However, to mimic the in vivo environment, the mechanics and geometry of the ECM must also be considered. Here, we studied the mechanical environment created in two 3D models, the overlay protocol (OP) and embedded protocol (EP). Mammary epithelial acini features were compared using OP or EP under conditions known to alter acinus organization, i.e. collagen crosslinking and/or ErbB2 receptor activation. Finite element analysis and active microrheology demonstrated that OP creates a physically asymmetric environment with non-uniform mechanical stresses in radial and circumferential directions. Further contrasting with EP, acini in OP displayed cooperation between ErbB2 signalling and matrix crosslinking. These differences in acini phenotype observed between OP and EP highlight the functional impact of physical symmetry in 3D tissue culture models.

Performance study of a CSMA based multiuser MAC protocol for cognitive radio networks: analysis of channel utilization and opportunity perspective

In the overlay medium access control (MAC) of cognitive radio networks, secondary user (SU) uses the spectrum portion which is assigned to primary user (PU), when PU is not using this spectrum at that time. In this article, a multiuser overlay MAC protocol is considered in which PUs and SUs are using time division multiple access and carrier sense multiple access (CSMA) MAC schemes, respectively. Firstly, new frame format and algorithm for the proposed MAC protocol are described, then the analytical modelling of this protocol is explained. In the SU network, Markov chain model along with the CSMA protocol is used for better utilization of the opportunity from the PU network (PUN). Channel utilization and probability of success are also derived and analyzed for this protocol with respect to idle time, collision (failure) time, various spectrum opportunities from PUN, number of SUs, and their fairness. This MAC scheme provides the optimal solution for channel utilization under a constraint on the probability of collisions. Numerical results are also provided to validate analysis of proposed MAC protocol and to investigate the performance behaviour of the optimal solution.

Contact graph routing in DTN space networks: overview, enhancements and performance

Delay- and Disruption Tolerant Networks (DTNs) are based on an overlay protocol and on the store-carry-forward paradigm. In practice, each DTN node can store information for a long time before forwarding it. DTNs are particularly suited to cope with the challenges imposed by the space environment. This paper is focused on routing in space DTNs, and in particular on contact graph routing (CGR) and its most representative enhancements, available in the literature, which are briefly surveyed in this work. Moreover, the applicability and the obtained performance of the DTN protocol stack and of the CGR have been evaluated by presenting results from real experimental experiences such as the Deep Impact Network experiment (employing the EPOXI space cruise), the JAXA jointly performed space link demonstrations with NASA (where the JAXA’s GEO relay satellite called Data Relay Test Satellite has been used), the Space Data Routers European Project, and the pilot operation of a DTN implementation on the International Space Station (ISS).

A QoS-aware reliable routing protocol for peer-to-peer overlay networks

In peer to peer overlay networks, the existing routing technique fails to address a more heterogeneous scenario, where the service provider and users are scattered across the internet. Moreover, the most research on routing aims at combining overlay routing protocol together with additional QoS mechanisms. In this paper, we propose a QoS aware reliable routing protocol for peer to peer overlay networks. When a source node wants to discover a route to destination, it performs route discovery mechanism. This technique selects the primary routing path based on the QoS metrics like packet loss, delay, bandwidth and hop count. If the primary path fails, the traffic is rerouted through backup paths. If a user requests the increased flow demand, a route restoration mechanism is executed. By simulation results, we show that the proposed approach minimises the delay and route failures while increasing the bandwidth utilisation and throughput.

3D P2P overlay over MANETs

We study the challenging problems of the mismatch between the overlay and the physical network and the resilience of the overlay structure in peer-to-peer (P2P) protocols over a mobile ad hoc network (MANET). Existing P2P protocols have used inflexible overlay structures to arrange peers and do not consider intra-neighbor relationships of peers when assigning logical identifiers. The intra-neighbor relationships of peers are crucial to exactly interpret the physical proximity of peers in an overlay and to avoid the mismatch between the overlay and the physical network that causes extensive routing overhead, larger average file discovery delay, increased false-negative ratio, and high average path-stretch. In this paper, we present a novel P2P overlay over MANETs that exploits a 3-dimensional overlay and 3D space that takes into account the physical intra-neighbor relationship of a peer and exploits a 3D-overlay to interpret that relationship. In the proposed protocol, each peer runs a distributed algorithm that exploits a 3D-overlay to calculate a consecutive logical identifier to a peer. Moreover, the protocol utilizes the 3D-overlay to maintain multi-paths to a destination peer that provides resilience against a node/link failure. Simulation results show that the proposed 3D-overlay outperforms the existing P2P overlay protocol in terms of routing overhead, average file-discovery delay, false-negative ratio, and average path-stretch.

FreeRec: an anonymous and distributed personalization architecture

We present and evaluate FreeRec, an anonymous decentralized peer-to-peer architecture, designed to bring personalization while protecting the privacy of its users. FreeRec's decentralized approach makes it independent of any entity wishing to collect personal data about users. At the same time, its onion-routing-like gossip-based overlay protocols effectively hide the association between users and their interest profiles without affecting the quality of personalization. The core of FreeRec consists of three layers of overlay protocols: the bottom layer, rps, consists of a standard random peer sampling protocol ensuring connectivity; the middle layer, PRPS, introduces anonymity by hiding users behind anonymous proxy chains, providing mutual anonymity; finally, the top clustering layer identifies for each anonymous user, a set of anonymous nearest neighbors. We demonstrate the effectiveness of FreeRec by building a decentralized and anonymous content dissemination system. Our evaluation by simulation, our PlanetLab experiments, and our probabilistic analysis show that FreeRec effectively decouples users from their profiles without hampering the quality of personalized content delivery.

An Extensive and Diverse Set of Molecular Overlays for the Validation of Pharmacophore Programs

The pharmacophore hypothesis plays a central role in both the design and optimization of drug-like ligands. Pharmacophore patterns are invoked to explain the binding affinity of ligands and to enable the design of chemically distinct scaffolds that show affinity for a protein target of interest. The importance of pharmacophores in rationalizing ligand affinity has led to numerous algorithms that seek to overlay ligands based on their pharmacophoric features. All such algorithms must be validated with respect to known ligand overlays, usually by extracting ligand overlay sets from the Protein Data Bank (PDB). This validation step creates the problem of which of the known overlays to select and from which proteins. The large number of structures and protein families in the PDB makes it difficult to establish a definitive overlay set; as a result, validation studies have rarely employed the same data sets. We have therefore undertaken an exhaustive analysis of the RCSB PDB to identify 121 distinct ligand overlay sets. We have defined a robust protein overlay protocol, which is free from subjective interpretation over which residues to include, and we have analyzed each overlay set on the basis of whether they provide evidence for the pharmacophore hypothesis. Our final data set spans a broad range of structural types and degrees of difficulty and includes overlays that any algorithm should be able to reproduce, as well as some for which there is very weak evidence for a conserved pharmacophore at all. We provide this set in the hope that it will prove definitive, at least until the PDB is greatly enriched with further structures or with radically different protein folds and families. Upon publication, the data set will be available for free download from the Web site of the Cambridge Crystallographic Data Centre.

Performance Evaluation of Multicast Overlay Routing Protocols

Abstract For almost three decades the multicast communication has been a subject of a dynamic research. It came to the world of the packet switching networks rather late and still has not become a fist class citizen of the Internet, yet the demand for such services is growing and thus the relevant technologies evolve persistently providing increasing quality and availability of the means of the group communication. The overlay approach to the multicast is an application layer realization which came to life due to certain deficiencies at the lower layers. In general the gain from using multicast for group communication instead of duplicated unicast links is that we avoid sending the same data many times through a single link. Such gain may be achieved wit the use of the router level mulitcast solution. The overlay solutions tend to approach his level of efficiency with a different degree of success. Therefore one of the main characteristics that is interesting when evaluating a particular overlay protocol is how well does it achieve the aforementioned gain. There are several metrics that allow for objective comparison of protocols in this regard. However this is not the only point of view to provide a valuable evaluation of the multicast overlay solutions. One of the important aspects of the modern group communication such as the IPTV or teleconferencing is the dynamic nature of the users’ participation. A particular group may be joined and left by multiple users at a very frequent rate which is critical to the resources management as well as to maintaining the integrity of the abstract communication structure, e.g. a tree spanning all the participants. In such case two major classes of the evaluation criteria emerge: the statical and the dynamical ones. They’re both very important and interdependent, however the means to measure them may differ significantly. In this article a wide variety of the multicast overlay protocols have been analysed and two of them have been chosen to be compared. The stress of the evaluation has been put on the dynamic aspects of the multicast overlay protocols operation.

P2P Overlay Maintenance Algorithm

Peer to peer networking has emerged as viable business model and systems architecture for internet scale application since it attracts millions of simultaneous participants. In P2P overlay network (collection of peer connections in a P2P network) peers join and leave the overlay arbitrarily and do not stay in the overlay for a predictable time. To ensure dependability of the overlay, peers with neighbor links to the joining or leaving peers requires updates. Therefore overlay maintenance protocols have to be devised to include efficient features that able to handle peer churn. In this paper we are focusing on the P2P overlay maintenance protocol through which the peers in the overlay maintains routing properties, referred as overlay maintenance. We have proposed an efficient method to find stale routing table entries in a way that retains the desired routing behavior since the look up query traffic and overlay maintenance traffic both compete for the underlying network bandwidth and resources, maintenance traffic should be constrained to that needed for target table accuracy.