In this paper we analyze the requirements for the complex information system used to support a modern global university. We outline the architecture for this system based on the emerging cloud computing platforms and present a use case based on the Google cloud.

The reduction of cost of fiber-optic technologies makes this medium more attractive for resolving transmission issues in the access part of telecommunication networks. Fiber-optic technologies are needed in this part of the telecommunications network, because services that are delivered to end-users demand more and more bandwidth. Thus, there are currently two scenarios for the introduction of fiber-optic technologies to the access network: step by step, where the proportion of optical cables in relation to metal cables is increasing as time passes, and directly, where the optical fiber is taken directly to the user’s premises (for example, in fiber-to-the-premises [FTTP] networks). It might seem that the end-user’s needs could be satisfied by simple technological upgrading. However, the number and types of services that are transmitted per access line can be wide ranging. The mutual interaction between these services may derogate the quality of one or more services. Therefore, it is necessary in the access networks, in addition to providing sufficient bandwidth, to provide mechanisms to protect the quality of service (QoS). For this purpose, the second International Workshop on Fiber Optics in Access Network ( FOAN ) was held in October 2011. In addition to standard topics on the optical physical layer, the focus of FOAN 2011 was on QoS in the access networks. Like in 2010, the workshop was held within the International Congress of the Ultra Modern Telecommunications and Control Systems ( ICUMT ). ICUMT 2011 was held in

Abstract The aim of this study is to investigate the use of an optical power meter in the field of passive optical networks. This instrument can provide certain spatial information about the fault at the physical layer in a passive optical network with cascade architecture, which is not possible in other optical networks. Attenuation of the optical path from the single optical network unit to the central office can be obtained by inserting a splitter 2/1 and measuring a difference in optical powers in the “on” and “off” states of this unit. The presented test results show the accuracy of measurement better than 2.5%.

Telecommunications networks throughout the transmission system are adopting fiberoptic technologies, because they are the most profitable part of the telecommunications infrastructure. Over time, with significant price reduction, optical technologies began to spread to all aspects of telecommunications. Currently, tremendous growth is being witnessed in the number of services to endusers of telecommunications networks. With a large number of services, the needs of end-users for bandwidth are also rising. Therefore, there is a basic rule to replace, as much as possible, short copper wires with an increasing proportion of fiber-optic cable in the subscriber fixed line of telecommunications networks. Using fiber-optic technology, where until recently there was a copper twisted pair, has its own specifics. The First International Workshop on Fiber Optics in Access Networks (FOAN 2010) was held in Moscow in October 2010 with the aim of gathering researchers and engineers who will provide more details about implementation specifics. The workshop was held within the ICUMT 2010 (International Congress on Ultra Modern Control Systems). The ICUMT is an annual international congress providing an open forum for researchers, engineers, network planners, and service providers in telecommunications and control systems targeted on newly emerging algorithms, systems, standards, services, and applications. The ICUMT is positioned as a premier international annual congress for the presentation of original and fundamental research and engineering results. The aim of the ICUMT is to bring together Russian and international players in telecommunications and control systems. The workshop was divided into two sessions, the first, called “Technology and Services,” aimed at showing the networks, services, and technologies in general. The second, entitled “System Performance and Optical Devices,” showed the recent events in this field. For this workshop, 15 articles were submitted; after the review process, 9 were accepted and presented, and 5 were selected for this special issue. The selected articles cover topics from a backbone network to top services, such as 3D (three dimensions) video.

This paper presents the comprehensive stochastic model of the TCP (Transmission Control Protocol) that aggregates all TCP states. The model provides the TCP connection throughput for a given packet loss probability, link capacity and link delay. The derived model incorporates assumption that packets coming after the first lost packet are not necessarily lost. Such assumption led to the model which adequately describes TCP behavior. The model derivation required determination of the transitional probabilities between TCP states, number of acknowledged packets and time intervals required for transitions. The obtained stochastic model was confirmed by averaged packet-level simulation results in ns2.

Nowadays, mobile terminal applications rapidly transform the meaning and context of health care services around the globe. Continuous monitoring of physical parameters is very important for improvement of the patient's life quality. Detection of ECG RR interval and QRS complex is crucial for diagnosis of heart diseases. In this paper, we present Bluetooth ECG Sensor Emulator in Matlab. We have tested the computation performances of mobile phones for monitoring and analysis of ECG signals. Three different peak detection algorithms were implemented using Java ME. MIT-BIH Arrythmia database signals were used for testing. Experimental results are discussed in order to determine their applicability to the real-time ECG telemonitoring.

This paper presents one approach to modeling of TCP connection during the slow start phase. Such modeling can be used for TCP connection analysis with reduced computation complexity compared to the packet-level simulators. Proposed model is validated by comparing the results obtained from ns-2 simulations. Introduction Application protocols mainly used on the Internet, such as HTTP or SMTP, use TCP protocol for reliable transport. TCP connection performance analysis can be carried out in two different ways. First one is simulation of TCP connection at the packet-level. This approach leads to accurate results but also requires long simulation time. Alternative approach is to model the TCP behaviour analytically, significantly reducing simulation time while simultaneously keeping accuracy at an acceptable level. This paper reviews models available in the literature and proposes an alternative analytical TCP model during the slow-start phase. TCP behavior can be described with different models. Packet-level models are the most accurate since they employ full TCP stack implementation. However, when analyzing large-scale networks or simple networks with high throughputs, packetlevel simulators are impractical due to long simulation time. An alternative approach is to use mathematical abstractions to model the TCP behavior. One way to abstract the TCP behavior through mathematical tools is to use differential equations. Another approach is based on probability analysis. In this approach, statistical formulas are used to describe TCP behaviour in different stages. Aggregating these models, the full TCP behavior could be obtained. In this paper, a probability model for the slow-start TCP stage is derived. The derived model is validated by comparing the results with the packet-level simulation tool ns-2 [7]. Finally, future directions for employment of probability models of other TCP stages are given. 1 TCP Protocol TCP is a reliable connection-oriented transport protocol for packet-switched networks. Reliability is achieved by employing acknowledgements (ACKs) [2]. Using ACKs and sequence numbers, the transmitter keeps the track of packets that are successfully delivered to the receiver. TCP operates in different stages: Slow Start, Congestion Avoidance, Fast Retransmit, Fast Recovery and Timeout. Transition between stages is determined by packet loss or acknowledgement of predefined number of packets. The window size determines the maximum number of packets that a transmitter may send before receiving the first acknowledgement. In the Slow Start phase, window size is incremented with every received ACK. Time interval, from departure of the first packet to the last packet in a window, represents round. The window size varies with the rate of the packet loss in the network. Hence, the packet loss probability increases with the number of sent packets due to the congestion in the network. Generally, window size wi grows in rounds and can be expressed as: 1 0 1 1 1 1 1 1 1 − − − − − ⋅ = ⋅ = + ⋅ = + = i i i i i i w w b w w b w w γ γ (1) where b is number of packets acknowledge by one ACK, and i is the round number and w0 is the initial window size. Total number of packets sent in slow start including the round i is 1 1 0 0 1 2 0 0 − − ⋅ = ⋅ + + + ⋅ + = − γ γ γ γ γ i i i w w w w ssdata (2) When a packet loss occurs during the slow start stage, there are two mechanisms to detect it. The first mechanism detects packet loss by using timeouts (TO). The second mechanism detects packet loss upon receiving three duplicate ACKs. SNE Simulation Notes Europe – Print ISSN 2305-9974 | Online ISSN 2306-0271 SNE 21(1), 2011, 45-48 | doi: 10.11128/sne.21.sn.10047 A Gogic et al. Probability Model for TCP Slow Start 46 SNE 21(1) – 4/2011 TN 2 Approaches for Modelling the Packet Switched Networks There are several approaches for modeling packet switched networks. The most accurate network models are packet-level models that keep track of individual packets. These models are implemented in network simulators, such as ns-2 [7]. The main drawback of packet-level model is a large computational effort required to keep track of each virtual packet in large scale simulations. Analytical models are based on idea to model the TCP network mathematically in order to reduce complexity involved in simulations [1, 6]. These models do not consider the network dynamics. They assume that round-trip time and loss probability are constant and there are no interactions between TCP flows. Fluid models are intended for simulation of packet networks. They overcome network scalability problem by keeping track of average quantities for relevant network parameters [5, 4]. Additionally, they use assumption that the bit rates are piecewise constant. Hybrid models use continuous time state variables with discrete time events [3]. Hybrid simulations require significantly less computational resources than packet level simulators. However, solution of hybrid equations is still necessary in order to simulate networks. 3 Probability Model for TCP Slowstart Stage There are two approaches for creating probability models of TCP behaviour. The source centric model assumes that packets leave the source with a certain loss probability [1]. The assumption taken by the second model is that the network generates loss probabilities for each packet [5]. Thus, the arrival process is represented by Poisson random process. In this paper we use the first approach with the further assumptions: the packet losses in two successive rounds are not correlated, packet loss occurs only in the forward direction; packet losses are independent of window size. Model detects packet losses by triple duplicates and TOs. Based on the source-centric model [1,6], we derived the expected value of number of packets sent in the slow start phase as a function of packet loss probability p, the initial size of congestion window wi and the number of packets acknowledged by one ACK. We further distinguish two boundary cases related to the position where packet was lost. The first case is characterized by the packet loss occurring at the beginning of the round (Figure 1). For the second case, the packet loss occurs at the end of the round (Figure 2). Figure 1. Slow-start phase, packet drop occurred at beginning of the round i. Figure 1 shows the number of acknowledge packets -1. Taking into consideration equation (2), we can write

In this paper we present ICT for providing real time two-way communication and the roll of wireless sensor networks for data acquisition in Smart grid. Architecture and overview of a power line communication technology is presented in our paper along with some advantages of this technology. The goal of this paper is to present the interoperability of power line communications (PLC) and wireless sensor networks technology. This paper also discusses the possibility of using this concept within the IMPONET project.

The paper presents a simple implementation model of the high-voltage power line communication (HV PLC) channel using digital filters. The model utilizes three identical finite impulse response (FIR) filters. The amplitude characteristic of the FIR filters matches the HV PLC channel amplitude characteristic for a given coupling, without taking into consideration reflection. The reflection phenomenon occurring at the HV power line terminals is implemented in the model by using a parallel feedback branch and additional filter delay corresponding to the traveling time of the reflected wave. The approach presented in this paper is applied to a 400 kV power line with three phase conductors in horizontal disposition. Results are given for two optimal couplings, middle phase to ground and outer phase to middle phase coupling.

The paper presents a method for the attenuation measurement of the optical path from ONU to OLT in GPON network. Optical power meter is connected to the fiber section via splitter in central office receiving optical signal from all ONU's. Optical power difference is measured in upstream signal with desired ONU in “on” or “off” state. The difference has a linear relationship with user's bandwidth. Finally paper describes an experimental setup for confirmation of proposal, the results differ by 2,5% from theoretically calculated. The system will improve the service reliability and reduce the maintenance cost.

This paper presents a methodology to develop a complete domain specific language (DSL) for simple finite state machine (FSM) modeling, utilizing metaprogramming techniques found in Ruby programming language. Additionally, two libraries for FSM modeling are reviewed. A simple vending machine model is used to demonstrate the effectiveness of the DSL code. The proposed techniques together with the SIP Servlet API can be combined with Ruby's web development environments to develop complex converged telecom applications.

The paper presents an approach to integrate dynamic programming languages with IMS application servers. Existing Java-based platforms for telecom applications are surveyed. Specific steps of integration of Ruby and JEE server are given. A proof of concept application is developed and deployed on an open-source Java Enterprise server.

This paper presents measurement results of frequency characteristics of the high-voltage power line in low radio-frequency range: amplitude and phase characteristic, group delay, and input impedance. Measurement results for the 400-kV overhead power-line under operation are presented together with the developed measurement methodology. The methodology provides a method to measure amplitude and phase characteristics, group delay and the return loss of the HV power line for a geographically distributed system utilizing an optical link as a return path. The measurement results confirm very low attenuation with a linear phase, but with oscillations present in all characteristics caused by reflection of the signal on the power line. The complete knowledge of frequency characteristics of the HV power line and noise description is crucial for the design of digital power-line carrier (PLC) systems.

This work presents an algorithm for the computation of frequency and time characteristics of the corona noise in power-line carrier communications. In the frequency domain, the corona noise is represented with a power spectral density and with a Gaussian noise voltage with variable root mean square value in the time domain. Simulations results are compared with measurements on an actual 400-kV power line.

The impulse noise in the HV power line channel is mainly caused by high voltage existing on conductors and station apparatus. Such impulse noise has repetition rate of SO or 150 Hz and is synchronous to power frequency period. In this paper, we have shown that the digital transmission via HV PLC channel have better performance if it is realized through the transmission of interleaved data blocks. The data frame duration must be adjusted to the periodicity of impulse noise or the power frequency period.