Analysis of the Performance of a Coherent SAC-OCDMA-OFDM-DWDM System Using a Flat Optical Frequency Comb Generator for Multiservice Networks.

A SAC-OCDMA-OFDM-DWDM system using a flat optical frequency comb generator and a coherent communication system is proposed in this research. The objective is to develop a novel OCDMA communication system that is appropriate and dedicated to multiservice networks. A comparison between the two codes, EDW and RD, has been presented. It has been concluded that the RD code system has better performance in terms of robustness and number of users than the EDW code. By analyzing the BER for several symbol rates and comparing it to the pre-FEC threshold, the proposed system demonstrates its effectiveness against linear and nonlinear effects. Performance evaluation of the proposed system is carried out via co-simulation of OptiSystem and MATLAB.

Towards Practical Applications in Modeling Blockchain System

Like multiservice networks, blockchain technology is currently experiencing significant development because of its decentralization and ability to organize secure, seamless, reliable data exchange and storage. Due to the significant demand for the technology, there is a need to analyze the impact of these technology processes on network characteristics to predict traffic behavior and ensure required quality indicators, as well as on the stability of public communication network elements when blockchain technology operates. Conducting a full-scale experiment is a time-consuming task that cannot always be accomplished, so in this paper, the authors propose considering approaches to modeling these systems and, as an example, propose to use a simulation system to assess the performance of the network and its elements.

Scientific Aspects of Structural and Parametric Simulation Modeling of Blockchain Systems

Over the past decade, in addition to multiservice networks, blockchain technology has undergone significant development due to the possibility of organizing a safe, integral, reliable exchange and storage of information. Due to the great demand for the technology, there is a problem of data transmission to the operators' networks. At the same time, a key task appears to consider the effect of this technology on network characteristics to predict traffic behavior on the network and ensure the required service quality indicators, as well as the stability of the state of the public communication network elements when the distributed ledger technology is operating. However, to consider and analyze the influence of technology in a full-scale experiment is a labor-intensive task that cannot always be performed, therefore, in this article, the authors propose to consider approaches to structural-parametric modeling of these systems.

DELAYS IN QUEUES OF QUEUING SYSTEMS WITH STATIONARY REQUESTS FLOWS

During all periods of the study of telecommunications systems traffic, the analysis was based on mass service theory. The subjects of the study here are request flows to be processed by some limited performance resources. Resource constraints and the random nature of requests’ receipt lead to refusals in processing or queues. The first works devoted to the analysis of teletraffic belong to A. K. Erlang. Request flows represented flows of requests for connections in networks with channel switching. Since requests were received from a large number of independent users, the flows of such requests could be defined as stationary, ordinary with no effect, or as recurring requests, with an exponential distribution of time intervals between neighboring requests. Connection request flows to a telephone exchange node are a superposition of a large number of low-intensity flows from independent users. Therefore, the fixed Poisson flow model describes the real flows in telephone exchanges with channel switching quite well. Therefore, the stationary Poisson flow model describes real flows in telephone exchanges with channel switching rather well. The emergence of telecommunications networks with packet switching, especially multiservice networks, showed the impossibility of using Poisson flow models for their analysis. The article is devoted to the analysis of delays in queues of queuing systems with correlated stationary flows of general type requests. The traffic of packets in multiservice networks is typically characterized by a high degree of correlation. On the basis of interval methods of analysis, the relations generalizing the Khinchin-Pollaczek formula for the average value of waiting time in queuing systems with flows of the general kind of requests are obtained. The main parameters to be analyzed when outputting the above formulas are time intervals between neighboring requests. It is shown that the values of time delays in queues depend on the dispersion and dispersion index of a random value characterizing the degree of additional maintenance of processed requests.

RESEARCH THROUGHPUT INDICATORS CORPORATE MULTISERVICE NETWORKS

The performance indicators corporate multi-service networks based on the architectural concept of the following Next Generation Network (NGN) and Future Networks (FN) using a number of innovative technologies are considered. A significant difference between such networks and previous generation networks is that the architecture of future networks is based on technologies software defined networks, virtualization network functions and the multimedia communications subsystem. As a criterion for complex performance indicators corporate multiservice networks, we selected throughput, the coefficient effective use hardware and software systems, various resources, and probability-time characteristics. As a result of the study, a method for calculating the complex throughput indicators corporate multiservice networks based on the architectural concept NGN and FN using SDN (Software Defined Networking), NFV (Network Functions Virtualization) and IMS (Internet Protocol Multimedia Subsystem) technologies is proposed. Th essence of the new method is to find relationships with which you can calculate the maximum throughput of the communication network and the areas feasible solutions of the basic equation that belong to it. System and technical analysis showed that the transmitted heterogeneous traffic has a special structure – self-similarity properties (scale invariance) and a quantitative assessment of the degree traffic self-similarity using the Hurst parameter. Based on the proposed calculation method, the complex indicators of corporate multiservice networks are examined taking into account the parameters traffic self-similarity, QoS (Quality of Service) and QoE (Quality of Experience). Resource management methods in network nodes were studied to improve the throughput characteristics taking into account the numerous QoS & QoE parameters and the coefficient effective use hardware and software systems was determined. Based on the calculation method, analytical expressions have been obtained to evaluate the complex indicators corporate multiservice networks in establishing connections and in providing multimedia services with the necessary parameters. A numerical analysis is carried out and a graphical dependence of the maximum network throughput on the total number software and hardware systems is constructed for a given system load factor.

Queuing System with Unreliable Servers and Inhomogeneous Intensities for Analyzing the Impact of Non-Stationarity to Performance Measures of Wireless Network under Licensed Shared Access

Given the limited frequency band resources and increasing volume of data traffic in modern multiservice networks, finding new and more efficient radio resource management (RRM) mechanisms is becoming indispensable. One of the implemented technologies to solve this problem is the licensed shared access (LSA) technology. LSA allows the spectrum that has been licensed to an owner, who has absolute priority on its utilization, to be used by other participants (i.e., tenants). Owner priority impacts negatively on the quality of service (QoS) by reducing the data bit rate and interrupting user services. In this paper, we propose a wireless multiservice network scheme model described as a queuing system with unreliable servers and a finite buffer within the LSA framework. The aim of this work is to analyze main system performance measures: blocking probability, average number of requests in queue, and average queue length depending on LSA frequencies’ availability.

POWER FOR PROCESSING APPLICATION FLOWS AND QUEUE SIZES IN MASS SERVICE SYSTEMS

The classical queuing theory studies time series processing under the assumption of sampling independence. However, the traffic of modern multiservice networks is usually strongly correlated and the methods of classical theory do not work. In this paper, we consider the cyclic process of queuing, conditional and unconditional mutual correlations. Conditional average values of queues are considered. The concept of processing power of the flow of applications in queuing systems (QS) is introduced. It is shown that the variable component of the indicated power is determined by the change in the load factor and corresponds to the conditional average size of the queue of applications in the QS.