OPTICAL ADD DROP MULTIPLEX- SURVEY

Transcription

1 International Journal of Computer Engineering and Applications, Volume X, Issue VI,June2016 OPTICAL ADD DROP MULTIPLEX- SURVEY Er Neeraj Sharma 1, Er. Daljit Kaur 2, Er Amandeep Kaur 3 1,2,3 Department of Electronics & Communication Engineering SSIETM ABSTRACT: An optical add-drop multiplexer is a device which is wavelength-division multiplexing systems for multiplexing and routing different channels. An optical add-drop multiplexer is a device which allows the insertion or extraction of one or more wavelengths from a fiber at a network node. Add and drop here refer to the capability of the device to add one or more new wavelength channels to an existing multi-wavelength WDM signal, and/or to drop (remove) one or more channels, passing those signals to another network path. This paper presents a survey on optical add drop multiplexer its types and its uses for the optical fiber communication. Keywords: optical add-drop multiplexer; Multiplexer; Demultiplexer; Optical fiber; WDM. [1] INTRODUCTION An optical add/drop multiplexer (OADM) is a device which allows the insertion or extraction of one or more wavelengths from a fiber at a network node. For example, an OADM might have the capability to drop and insert three wavelengths from a set of N being transported over a single fiber. [1]The remaining N -3 wavelengths pass unaffected through (also called express through) the OADM to the next node. Without an OADM, if only three wavelengths out of N >> 3 are needed at the local node, then all the other wavelengths also would need to be processed there by means of optoelectronic transceivers. This will greatly increase the equipment costs at that node. Thus the advantage of add/drop function is that no signal processing is required for the set of wavelengths that passes straight through the OADM. The OADM can reside at an optical amplifier site in a long-haul network or it can be located at a node in a metro network[2]. Depending on how it is designed, an OADM can operate Er Neeraj Sharma 1, Er. Daljit Kaur 2, Er Amandeep Kaur 3 12

2 OPTICAL ADD DROP MULTIPLEX- SURVEY either statically in a fixed add/drop configuration or it can be reconfigured dynamically from a remote network management site. OADM has two types: FIXED OADM: A fixed optical add/drop multiplexer is simply referred to as an OADM. A fixed OADM obviously is not as flexible as a ROADM and may require a change of hardware components if a different set of wavelengths needs to be dropped or added. RECONFIGURABLE OADM: A dynamic device is called a reconfigurable OADM (ROADM). Depending on whether an engineer is designing a metro or a long-haul network, different performance specifications need to be addressed when implementing an optical add/drop capability in the network[8]. In general, because of the nature of the services provided, changes in the add/drop configuration for a long-haul network occur less frequently than in a metro network where there tends to be a high turnover rate in service requests and in wavelengths being transported. In addition, compared to a metro network the wavelengths spacing usually is much narrower in a long-haul network and the optical amplifiers which are used must cover a wider spectral band. [2] OADM CONFIGURATIONS A number of different OADM configurations are possible. These can be a series of dielectric thin-film filters, an arrayed waveguide grating (AWG), a set of liquid crystal devices, or a series of fiber Bragg gratings used[4] in conjunction with optical circulators. The architecture selected for a particular application depends on implementation factors such as the number of wavelengths should be dropped and added at a node, the desired modularity of the OADM (e.g., how easy is to upgrade this device), and the constraint of whether random individual wavelengths or a neighboring group of wavelengths should be processed. Here we assume that N wavelengths traveling on a single fiber enter the OADM and a subset M of them is processed at the node. After processing, these M wavelengths are reinserted onto the fiber line to rejoin the through-going N M channels. In the configuration illustrated in figure2.1, all N incoming wavelengths are separated into individual channels at the OADM input by means of a wavelengths demultiplexer[3]. This gives a very versatile architecture, since any of the N wavelengths can be dropped, processed at the node, and then reinserted onto the outgoing fiber by means of a wavelength multiplexer. In the illustration given here, M wavelengths are dropped and the remaining N M channels individually pass through the OADM. The M dropped wavelengths are labeled i through k to indicate that any combination of M wavelengths selected from the N incoming light channel can be dropped and added[8]. However it is not cost effective for dropping and adding a small fraction of the incoming wavelengths. [Figure 1] shows a more modular OADM architecture. Here the N incoming light channels are split into several bands of wavelengths. This function can be achieved using either a set of thin-film filters or an AWG 13

3 International Journal of Computer Engineering and Applications, Volume X, Issue VI,June Figure.1 OADM architecture The band to be dropped can be sent through a second demultiplexer followed by processing of the individual wavelengths. As an example, if N=12 and three wavelengths need to be dropped, the incoming wavelengths can be divided into four bands of three wavelengths each. Added lightwave channels go through two stages of multiplexing to rejoin the passthrough bands. An advantage of this approach is that for future OADM upgrades to drop another wavelength band at this node, network engineers can incorporate another secondstage demultiplexer to handle the next desired wavelength band. [2.1] RECONFIGURABLE OADM The task of reconfiguring a fixed OADM manually may require several days of planning and implementation of hardware changes. In contrast, the use of ROADM gives service provides the ability to reconfigure a network within minutes from a remote network-management console. The dynamic flexibility to drop and add selected wavelengths quickly at a particular node upon customer demand for new or expanded services is known popularly as services is known popularly as service provisioning on the fly[8]. This is particularly important in metro network where changes in service request tend to be significantly more dynamic that in longhaul networks and clients expect very rapid responses to their requests. Such service requests can have fairly diverse origins such as time-varying business application, on-demand entertainment, and emergency or disaster-response communications. A variety of ROADM architectures are possible. In this section we will look at three types. These are based on wavelength blockers, arrays of small switches, and wavelengthselective switches. Section 13.6 describe the concept of an optical cross-connect, which uses a more complex architecture of multiple wavelength-selective switches. Each ROADM can have a number of alternative configuration and different operational characteristics. The design of a particular ROADM depends on factors such as cost, reliability, technology maturity, desired network operating flexibility, and upgrade capability of the equipment. Er Neeraj Sharma 1, Er. Daljit Kaur 2, Er Amandeep Kaur 3 14

4 OPTICAL ADD DROP MULTIPLEX- SURVEY Before going into architecture details, let us first look at some desired features and technology. [3] DESIRED FEATURE OF OADM WAVELENGTH DEPENDS: If the architectures are wavelength-dependent they are said to be colored or have colored parts. When the ROADM operation is independent of wavelength it is referred to as being colorless or having colorless parts[7]. ROADM DEGREE: The degree of ROADM refers to the number of bidirectional multiwavelength interfaces the device support [6]. Thus a degree-2 ROADM has two bidirectional WDM interfaces and a degree-4 ROADM can support up to four bidirectional WDM interfaces, for example, in north, south, east and west directions. REMOTE RECONFIGURATION: The ability to change the ROADM configuration from a remotely located network-management workstation is an important feature, since if greatly reduces operations costs by eliminating the need for a service person to visit the ROADM site in order to manually upgrade the device. EXPRESS CHANNELS: The ability to have express channels that allow a selected set of wavelengths to pass through the node without the need of optical-to-electrical-to-optical conversion saves the expense of having optical transceivers for those wavelengths. MODULAR EXPANSION: To avoid the initial high set up cost to connect transmit and receive equipment to each add/drop port, service provides usually first activate the minimum number of ports needed to support current traffic and then later add more channels as the service demand increases. This is known popularly as the pay-as-you-grow approach. MINIMUM OPTICAL IMPAIRMENT: Having an express wavelength feature requires a careful engineering design to avoid the accumulation of optical signal impairments as a particular wavelength set passes wavelength-dependent attenuation, ASE noise, and polarization- dependent loss. [4] ANALYSIS AND CONCLUSION OADM are devices in high demand both in LAN and in long haul system. It is an important device in routing the wavelengths. OADM reduced the circuitry and also it reduces the cost of additional circuit required. One can easily set up the new ROADM with small circuit and then if the demand is high then additional circuit can be added to it. 15

5 International Journal of Computer Engineering and Applications, Volume X, Issue VI,June REFERENCES [1] G. KEISER Optical fiber communication 4 th edition McGraw-Hill Education. [2] G. P. Agrawal Optical fiber communication [3] G. P. Agrawal Nonlinear Fiber Optics [4] W. Suwancharoen Chaotic signal generation and cancellation using a micro ring resonator incorporating an optical add/drop multiplexer Volume 280, Issue 2, 15 December 2007, Pages [5] Retrieved from /cemil/dwdm/ pdf [6] Retrieved from [7] A. Nabih Z. Rashed Optical Add Drop Multiplexer (OADM)Based on Dense Wavelength Division Multiplexing Technology in Next Generation Optical Networks international Journal of Multimedia and Ubiquitous Engineering Vol. 7, No. 1, January, [8] N.K.Shukla and K.Dixit Reconfigurable Optical Add and Drop Multiplexers A Review Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 1, March2014 Er Neeraj Sharma 1, Er. Daljit Kaur 2, Er Amandeep Kaur 3 16

6 OPTICAL ADD DROP MULTIPLEX- SURVEY Author[s] brief Introduction 1. Neeraj Kumar Sharma AP ECE at St Soldier Institute of Engineering & Technology Jalandhar. 2. Daljit Kaur AP ECE at St Soldier Institute of Engineering & Technology Jalandhar. 3. Amandeep Kaur AP ECE at St Soldier Institute of Engineering & Technology Jalandhar Corresponding Address- (Pin code and Mobile No) ( ADDRESS OF All authors same) Vill Bhoolpur Po Miani, Tehsil Dasuya Distt Hoshiarpur,Punjab Contact No: Neeraj Kumar Sharma Daljit Kaur Amandeep Kaur