Subscriber Access Network Research Articles

ПРОВЕДЕННЯ ЛАБОРАТОРНИХ РОБІТ В ПРОЦЕСІ ЗМІШАНОГО НАВЧАННЯ СТУДЕНТІВ ЗА МОДЕЛЛЮ «ПЕРЕВЕРНУТИЙ КЛАС» В ГАЛУЗІ 17 ЕЛЕКТРОНІКА, АВТОМАТИЗАЦІЯ ТА ЕЛЕКТРОННІ КОМУНІКАЦІЇ

In the article, the authors clarify the importance and role of laboratory work in the process of training future specialists in the field of 17 ‒ Electronics, Automation and Electronic Communications. In particular, the use of laboratory workshops as a component of the educational process, the functionality of which is aimed at consolidating theoretical knowledge and developing practical skills necessary for further professional activity, is substantiated. The authors outline the defining aspects of the introduction of blended learning technologies in laboratory work aimed at developing the following skills in future professionals: use of instruments and equipment, measurements in telecommunication networks, design of instruments, creation of original installations and devices, development of new technologies, etc. It is shown that the flipped classroom model is one of the formats of blended learning, according to which the theoretical part of the educational material is studied by students at home individually, and during classes (online) practical application and consolidation of knowledge is implemented. The article describes the experimental part of the study, which includes the experience of teachers of the Kyiv Professional College of Communications and Vinnytsia Technical Professional College: in the process of teaching the discipline "Subscriber Access Networks", a series of laboratory works was conducted according to the "Flipped Classroom" model. The authors have established that laboratory workshops in the process of blended learning based on the flipped classroom model have a number of advantages, in particular, flexibility in the distribution of educational content in accordance with the requirements and conditions of participants in the educational process (establishing proportionality), release of a significant share of real learning time for practical activities ‒ focus on the formation of practical skills and abilities of future specialists.

DESIGN OF A PERMITTED NETWORK USING FIBER-OPTIC-BASED SOLUTIONS MATHEMATICAL MODELING

The main goal of the research is to increase the speed of exchange in broadband subscriber access networks, primarily using PON technology, since the needs of subscribers are constantly growing and modern structures can no longer provide them. This article discusses the PON technology, types of WDM technology, equipment designed for communication networks using WDM, designs and parameters of WDM multiplexers. The possibility of implementing WDM-TDM hybrid multiplexing in existing PON systems is considered. Conclusions are drawn about the relevance of the use of this technology in order to modernize existing access networks. The rapid development of technologies for the production of electronic optical devices and optical fibers made it possible in the mid-80s to use fiber to connect individual users and organizations. The launch of the first distribution networks was carried out using point-to-point topologies, but a few years later the technology of passive optical networks (PON) was created, which allows organizing point-to-point topologies.

Devising a method to control the operational quality and reliability of fiber-optical communication lines

The lack of recommendations in the normative and technical documentation related to fiber-optic communication lines (FOCL) for assessing their technical condition necessitated devising a method to control the lines' quality and reliability of operation. The method creates the basis for calculating the quality and reliability indicators of FOCL operation and suggests measures to improve them. It determines the methods of control, as well as the acquisition, accounting, and analysis of damage statistics with and without interruption of communication. The graphic sequence of implementation of the stages of the method demonstrates that resolving the task to control these indicators should involve: – managing the acquisition and actual acquisition of operational data on damages (the causes, nature, quantity, the duration of communication breakdown and complete elimination of damage); – determining the quality and reliability indicators of FOCL operation annually; – analysis of the obtained results and the development (correction) of measures to comply with the norms of these indicators; – the implementation of measures to comply with the norms of quality and reliability of FOCL operation (if necessary). Based on the operational data from a line operator acquired over three years in the specified climatic zone (a cable of the type OKLBg-3 DA12-3×4E-0.4F3.5/0.22N18-12/0), the methodical component of the method was examined. The obtained results on the operational quality (damage density, average damage duration, break (downtime) of communication) and reliability indicators (FOCL readiness factor) of a subscriber access network without reservation showed that the line had low efficiency. The communication breakdown over three years amounted to K=12,569.8 stream∙hours. The downtime at this volume of digital stream∙hours has led to significant economic losses. Line operators have been given recommendations for the proper FOCL operation and ensuring a normalized value of the line readiness coefficient. To this end, it is necessary to reduce the time to re-link and prolong the line's failure-free operation

Performance analysis of a hybrid optical CDMA/DWDM system against inter-symbol interference and four wave mixing

This paper reports the implementation and theoretical model for analyzing an optical CDMA/DWDM hybrid system to reduce two major problems, the Inter-Symbol Interference (ISI) and the Four-Wave Mixing (FWM) effects and improve the performance of optical subscriber access networks by using Zero Cross-Correlation (ZCC) optical codes, which helps to reduce the effect of the Multiple Access Interference (MAI). A squeezing method is used in the proposed hybrid system to completely suppress the ISI. In this method, the sequence interval of the signature code is squeezed into a duration of less than one-bit. The hybrid system is capable of accommodating 120 optical CDMA users carried by only 10 DWDM wavelengths spaced by 0.2 ​nm with 60 ​Gb/s/wavelength transmitted over 105.075 ​km of optical fiber. The result shows that the optimum interval of the code sequence is a quarter (i.e., 25%) of the bit duration. Moreover, the results reveal that the CDMA technology based on the spread spectrum is capable of increasing the nonlinear tolerance of the proposed hybrid system as the energy of bits is distributed over the chip sequence code. Also, the number of ones/weight and the positions between them have a significant effect on the performance of the proposed hybrid system.

For the security of telecommunication networks on the application program package OPNET Modeler v.14.5 and the use of the «NetDoctor» module

The work is focused on modeling in OPNET Modeler v.14.5 wireless subscriber access network for its analysis and research by using and applying the NetDoctor module to ensure the security of the built network. Wireless communication is used, as it is accepted, in networks, connecting and wired (cable) means, and give the opportunity to take a convenient, fast and economical solution of problems arising in the process of solution and modernization of cable networks. Wireless communications, therefore, should be considered not a complete alternative to cable networks, but only an alternative technology for the implementation of individual segments or even entire levels of the designed, extensible or modernizing computer network. Detection of used erroneous technologies in the process of building and modeling of telecommunication networks ensures the security of their functioning and predicts their reliable building structure at their design. In our work we use the NetDoctor module of the program package of OPNET Modeler v.14.5 to test the security of the built wireless network.

The approach for supporting synchronous Ethernet in 10G EPON

In recent, many countries and research institutes have been studying how to construct the high-speed subscriber access network. Task Force team of IEEE 802.3ah has accomplished the standardization of EPON which is the next generation subscriber access network. EPON doesn't still have the bandwidth enough to support the new service(e.g various multimedia service) which demands the high bandwidth. For these new multimedia services,10G EPON is the next generation subscriber access network which expanded the up-down bandwidth range of 1G EPON 10 times in order to support demanding high bandwidth. We have proposed the model which can accommodate IEEE 802.1 AVB traffics smoothly in 10G EPON and suggesting the Intra-ONU scheduling model which makes this model operate effectively.

Differential Bandwidth Allocation Method using Upstream Bandwidth Wavelength Division of EPON

Abstract The subscriber access network is cause of the bottleneck phenomenon because equipment and infrastructure were not originally designed for busty high-bandwidth traffic between MAN(Metro Area Network) and LAN(Local Area Network). Whether riding on shorter copper drops or optical fiber, Ethernet is emerging as the future broadband protocol of choice, offering plug and play simplicity, and low cost. EPON(Ethernet Passive Optical Network) combines point-to-multipoint optical infrastructure with low-cost high-bandwidth Ethernet. The future broadband access network will be a combination of point-to-point and point-to-multipoint Ethernet, optimized for transporting IP data, as well as time critical voice and video. EPON is being considered as a novel communications infrastructure for next-generation broadband access network for the convergence of low-cost Ethernet equipment and low-cost fiber infrastructure. But, EPON has a problem with duplex multimedia services. It is the insufficiency of bandwidth for upstream. Because all ONUs use a shared transmission media for upstream. In this paper, we addressed the problem of upstream bandwidth in EPONs. We presented a wavelength division EPON supporting QoS in the differentiated services framework.

동시 사용자의 간섭을 제거한 광 주파수 및 시간 영역 광 CDMA를 이용한 광 가입자 망의 제안

In this paper, we propose optical subscriber access network to eliminate multiple access interference using 2 dimensional(D) optical frequency and time domain CDMA method. We have numerically analyzed the characteristics of proposed system. It is seen that the excess intensity noise is the major limiting factor to the system. Also it is seen that the number of simultaneous subscribers is four times as large as the conventional ID optical system under the same bit error ratio.

Fair Queueing With Service Envelopes (FQSE): A Cousin-Fair Hierarchical Scheduler for Subscriber Access Networks

In this paper, we propose and investigate the characteristics of a fair queueing with service envelopes (FQSE) algorithm-a hierarchical fair-share scheduling algorithm for access networks based on a remote scheduling system such as Ethernet passive optical networks (EPON) or cable TV network. FQSE is designed to overcome the limiting factors of a typical remote scheduling system such as large control-plane delay, limited control-plane bandwidth, and significant queue switch-over overhead. The algorithm is based on a concept of service envelope-a function representing the fair allocation of resources based on a global network condition called satisfiability parameter (SP). We define properties of cousin-fairness and sibling-fairness and show the FQSE to be cousin-fair. FQSE is unique in that it is the only hierarchical algorithm that is simultaneously cousin-fair. Furthermore, we show the necessary techniques to adapt FQSE to variable-sized packet-based networks. We analyze FQSE performance in EPON serving 1024 independent queues and demonstrate FQSE's ability to provide guaranteed bandwidth to each queue and to share the excess bandwidth fairly.

데이터속도에 무관하게 동일 성능을 보장하는 광주파수영역 CDMA를 이용한 초고속 멀티미디어 광 가입자망의 제안

In this paper, we propose ultra-fast multimedia optical subscriber access network using optical frequency domain CDMA method in order to access the multimedia with multiple data rates. We numerically analyze the effects of spectral power distortion in the light source for the optical CDMA system modified PN codes and FBG(Fiber Bragg Grating)s. In the proposed multiple-rate multimedia access optical networks, the performances such as BER(Bit Error Rate) are the same for all data regardless of data rates in the case of the same number of simultaneous ONU. In the proposed ultra-fast multimedia optical subscriber access network, the performances for all data are much more improved than those in the conventional system.

An OCDMA Scheme to Reduce Multiple Access Interference and Enhance Performance for Optical Subscriber Access Networks

We propose a new optical code division multiple access (OCDMA) scheme for reducing multiple access interference (MAI) and enhancing performance for optical subscriber access networks using modified pseudorandom noise (PN)-coded fiber Bragg gratings with bipolar OCDMA decoders. Through the bipolar OCDMA decoder and the modified PN codes, MAI among users is effectively depressed. As the data are encoded either by a unipolar signature sequence of the modified PN code or its complement according to whether the data bit is 1 or 0, the bit error ratio (BER) can be more improved with the same signal to interference plus noise ratio over the conventional on-off shift keying-based OCDMA system. We prove by numerical analysis that the BER of the proposed bipolar OCDMA system is better than the conventional unipolar OCDMA system. We also analyze the spectral power distortion effects of the broadband light source.

Evolutionary architecture for an all‐services ATM access network

AbstractThis paper presents a flexible concept for a broadband subscriber access network which minimizes investment costs by predominantly using the existing network infrastructure. The target network may consist of either a coaxial tree‐and‐branch structure or symmetrical copper pairs to the subscriber, and is connected to the central head station with the aid of optical feeder lines which can be implemented or enhanced by a passive optical network (PON). In the event of an increase in bit rate requirements, the coaxial network can be expanded by dividing it into smaller, optically fed subnetworks or by supplementing it with optical overlay systems. Flexibility, expandability and low costs are achieved through the standard ATM format implemented for the signals of all interactive services down to the network termination units on the subscriber side. Those signals are transmitted in the coaxial network in frequency bands above the CATV band in accordance with a multiple of the CATV channel width to ensure that the modulation and demodulation is implemented in a cost‐efficient manner while providing ‘bit rate on demand’ for a suitably high number of subscribers. Separation of the network termination unit from the customer premises equipment enables a flexible, cost‐efficient subscriber configuration to be selected, existing domestic wiring to be used and several completely different subscriber terminals to be simultaneously connected.

Multichannel wavelength-switched transmitters and receivers-new concepts for broadband networks and distributed switching systems

Three component concepts for use in high-density wavelength-division-multiplexed optical systems are described. The applications envisaged for these components include broadband overlay for subscriber access networks and ultrahigh-capacity packet switching for telecommunications or parallel processing computer applications. The components each use a dispersive optical grating and integrated array of optoelectronic transducers to form a component with precisely defined multiple operating wavelength channels. Multichannel laser transmitter and direct detection receiver components suitable for up to about 50 independent channels separated by 1-2 nm in the 1300- to 1600-nm-wavelength range are described. >