PON Passive Optical Networking

PON Passive Optical Networking
During class please switch off your mobile, pager or other that may interrupt. Entry level requirements: General telecom concepts Suggested duration: 1 day (or 6 hours) Normal class hours: 8:30h  12:00h 13:00h  16:30h Teknoloji tanıtımı Alcatel-Lucent University Istanbul 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Dersin hedefleri Dersimiz sırasında...
Fiberlerin nasıl çalıştığını ve uçtan uca optik iletişimde kullanılan elemanları öğreneceğiz Fiber içi yansıma, transmitter(gönderici), amplifier(güçlendirici), receiver(alıcı), splitter(ayırıcı), … Pasif Optik Ağın (PON) temel bileşenlerini açıklayacağız PON ağında kullanılan elamanların işlevlerini tanımlayacağız Temel PON terminolojisini kullanıyor olacağız 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiber Optik Temel . . . . . p. 4 PON standartı . . . . . p. 36
İçerik Fiber Optik Temel p. 4 PON standartı p. 36 GPON Temel p. 39 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberin avantajları Çok yüksek bant genişliği
Az yer kaplayan, hafif kablolar Paralel fiber kablolar arasında crosstalk oluşmaması Inductive interferans oluşmaması Yüksek kalitede iletim Düşük kurulum ve işletim maliyetleri Extremely high bandwidth Fiber today has bandwidth capability theoretically in excess of 10Ghz and attenuations less than 0.3 db for a kilometer of fiber. The limits on transmission speed and distance today lies largely with the laser, receiver and multiplexing electronics. With the future advent of stable narrow line single-mode lasers and coherent optics, 10 to 100 Gb/s transmission is possible. Smaller diameter – lighter weight cables Even when fibers are covered with protective coatings, they still are much smaller and lighter than equivalent copper cables. Negligible crosstalk In conventional circuits, signals often stray from one circuit to another, resulting in other calls being heard in the background. This crosstalk is negligible with fiber optics even when numerous fibers are cabled together. Immunity to inductive interference Fiber optic cables are immune to interference caused by lightning, nearby electric motors, relays, and dozens of other electrical noise generators that induce problems on copper cables unless shielded and filtered. High quality transmission Fiber routinely provides communications quality orders of magnitude better than copper or microwave, this as a result of the noise immunity of the fiber transmission path. (BER: 10-9 – for fiber, 10-5 – 10-7 for copper or microwave) Low installation and operating costs Low loss increases repeater spacing, therefore reducing the cost of capital in the outside plant. The elimination (or reduction) of repeaters reduces maintenance, power and operating expenses. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiber Optiğin Yapısı Core (çekirdek) Cladding (kaplama)
Fiberin içinde ışığın dolaştığı ince cam merkez Cladding (kaplama) Çekirdeğin içinde dolaşan ışığı merkeze geri yansıtmak için etrafını saran dış malzeme Coating (koruma) Fiberi dış zararlardan ve nemden koruyan plastik kaplama If you look closely at a single optical fiber, you will see that it has the following parts: core - thin glass center of the fiber where the light travels cladding - outer optical material surrounding the core that reflects the light back into the core coating - plastic coating that protects the fiber from damage (abrasion, crushing, chemicals, …) and moisture Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiber Optiğin Türleri glass (Cam) plastik plastic-clad silica
Merkezi ve kaplaması cam En düşük attenuation (zayıflama) En yaygın kullanılan plastik Merkezi ve kaplaması plastik En yüksek attenuation (zayıflama) plastic-clad silica Cam merkez – Plastik kaplama Hafif attenuation (zayıflama) In almost all cases (for telecommunication fibers) the core and the cladding are made of silica glass (SiO2 ) --- Fiber optics can be defined as that branch of optics that deals with communication by transmission of light through ultrapure fibers of glass or plastic. It has become the mainstay or major interest in the world of electro-optics, the blending of the technology of optics and electronics. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiber optik tipleri G.651 – MMF – Multi-mode fiber
Büyük çekirdekli: micron çapında Kızıl ötesi ışığı yansıtır (dalgaboyu = 850 nm - 1,300 nm) light-emitting(ışık-yayıcı) diyodlar G.652 – SMF – Single mode fiber Küçük çekirdekli: 8-10 micron çapında Lazer ışığını iletir (dalgaboyu = 1,200 nm - 1,600 nm) Lazer diyodlar The glass used in a fiber-optic cable is ultra-pure, ultra-transparent, silicon dioxide, or fused quartz. During the glass fiber-optic cable fabrication process, impurities are purposely added to the pure glass to obtain the desired indices of refraction needed to guide light. Germanium, titanium, or phosphorous is added to increase the index of refraction. Boron or fluorine is added to decrease the index of refraction. Other impurities might somehow remain in the glass cable after fabrication. These residual impurities can increase the attenuation by either scattering or absorbing light. --- For data center premise cables, the jacket color depends on the fiber type in the cable. For cables containing SMFs, the jacket color is typically yellow, whereas for cables containing MMFs, the jacket color is typically orange. For outside plant cables, the standard jacket color is typically black. Single mode fibers are the most prominently used type in telecommunication applications. 245 um 125 um 8 – 62.5 um Cladding Coating Core 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Reflection (yansıma) ve refraction (kırılma)
Dolaşan ışın Yansıyan ışın ac a2 n1.sin(ac) = n2.sin(90°) a1 n1 n2 a2 Kırılan ışın n1.sin(a1) = n2.sin(a2) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Toplam iç yansıma Yapı Mesafe Sinyal degredasyonu (kaybı)
Işık kaplamadan sürekli yansıyarak çekirdek içerisinde dolaşır Mesafe Kaplama yansıyan ışığı soğurmadığı takdirde ışık çok büyük mesafelerde ilerleyebilir Sinyal degredasyonu (kaybı) Camın içinde saf olmayan bölümlerin sebebiyet verdiği kayıp Scattering(Saçılım),Absoption(Soğrulma) cladding The light in a multi-mode fiber-optic cable travels through the core by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances. However, some of the light signal degrades within the fiber, mostly due to impurities in the glass. The extent that the signal degrades depends on the purity of the glass and the wavelength of the transmitted light (for example, 850 nm = 60 to 75 percent/km; 1,300 nm = 50 to 60 percent/km; 1,550 nm is greater than 50 percent/km). Some premium optical fibers show much less signal degradation -- less than 10 percent/km at 1,550 nm. For single-mode fiber, the fiber operates as a waveguide. --- Attenuation is principally caused by two physical effects: absorption and scattering. Absorption removes signal energy in the interaction between the propagating light (photons) and molecules in the core. Scattering redirects light out of the core to the cladding. Kabul edilir açı core 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Scattering (Saçılım) If the scattered light maintains an angle that supports forward travel within the core, no attenuation occurs. If the light is scattered at an angle that does not support continued forward travel, however, the light is diverted out of the core and attenuation occurs. Depending on the incident angle, some portion of the light propagates forward and the other part deviates out of the propagation path and escapes from the fiber core. Some scattered light is reflected back toward the light source. This is a property that is used in an optical time domain reflectometer (OTDR) to test fibers. The same principle applies to analyzing loss associated with localized events in the fiber, such as splices. ORL – Optical Return Loss Due to collisions of photons with impurities in the fiber, some are reflected back Physical contact splices cause huge optical return losses too! Işın fotonlarının çekirdek camının saf olmayan bölümleriyle karşılaşması sonucu oluşan saçılım “saçılım ışığın kaplamadan dışarı yönelmesine sebep olur” optical return 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Absorption (Emilim) Kızıl ötesi emilim
Scattering --- When attenuation for a fiber-optic cable is dealt with quantitatively, it is referenced for operation at a particular optical wavelength, a window, where it is minimized. The most common peak wavelengths are 780 nm, 850 nm, 1310 nm, 1550 nm, and 1625 nm. The 850-nm region is referred to as the first window (as it was used initially because it supported the original LED and detector technology). The 1310-nm region is referred to as the second window, and the 1550-nm region is referred to as the third window. Material absorption occurs as a result of the imperfection and impurities in the fiber. The most common impurity is the hydroxyl (OH-) molecule, which remains as a residue despite stringent manufacturing techniques. Short wavelengths are scattered more than longer wavelengths. Any wavelength that is below 800 nm is unusable for optical communication because attenuation due to Rayleigh scattering is high. At the same time, propagation above 1700 nm is not possible due to high losses resulting from infrared absorption. Kızıl ötesi emilim Fiber içinde dolaşan ışık fotonlarının cam molekülleri ile olan etkileşiminden ötürü oluşan emilim 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Dalgaboyunun bir fonksiyonu – Zayıflama -
0,85 µ band 1,30 µ band 1,55 µ band 2.0 1.8 1.6 1.4 1.2 Zayıflama (dB/Km) 1.0 0.8 0.6 0.4 The transmission loss or attenuation of an optical fiber is perhaps the most important characteristic of the fiber, as it generally is the determining factor as to repeater spacing, and the type of optical transmitter and receiver to be used. The attenuation of light through glass depends on the wavelength of the light. For the kind of glass used in fibers, the attenuation is shown in decibels per linear kilometer of fiber. The figure shows the near infrared part of the spectrum, which is used in practice. Visible light has slightly shorter wavelengths, from 0.4 to 0.7 microns (1 micron is 10-6 meters). Three wavelengths bands are used for communication. They are centered at 0.85, 1.30 and 1.55 microns, respectively. The latter two have good attenuation properties (less than 5 percent loss per kilometer). The 0.85 micron band has higher attenuation, but the nice property that at that wavelength, the lasers and electronics can be made from the same material (gallium arsenide). All the three bands are 25,000 to 30,000 GHz wide. Typical low loss fibers have attenuations of between 0.3 to 3dB/km. Contrast this attenuation with the ones for coaxial cable!! For fibers and coaxial cables alike, the losses are a function of the frequency of the signal carrier. Coax attenuation varies as the square of frequency with signal carriers in the DC to hundreds of megahertz range. With fiber, the usable carrier frequency (band of low attenuation) is in the terahertz range, and therefore we designate optical carrier frequency in terms of its wavelength. Attenuation is therefore specified at certain wavelengths rather then at certain frequencies. The most common impurity is the hydroxyl (-OH) molecule, which remains as a residue despite stringent manufacturing techniques. These radicals result from the presence of water remnants that enter the fiber-optic cable material through either a chemical reaction in the manufacturing process or as humidity in the environment. Recent advances in manufacturing have overcome the 1380-nm water peak and have resulted in zero-water-peak fiber (ZWPF). 0.2 0.0 1.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.8 Dalgaboyu (microns) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Uçtan uca fiber optik iletişim
Optik Verici (transmitter) Işık sinyalini üretir ve kodlar Optik Güçlendirici (amplifier) Uzun mesafeler için ışık sinyalini güçlendirmek amacıyla kullanılabilir Optik Alıcı (receiver) Işık sinyalini alır ve kodunu çözümler Fiber Optik Kablo Işık sinyalinin iletiminde kullaınılır The basic function of an optical fiber relay system (or optical fiber link) is to transport a signal from some piece of electronic equipment (e.g., a computer, telephone or video device) at one location to corresponding equipment at another location with a high degree of reliability and accuracy. Of course the optical fiber is one of the most important elements in an optical link. A variety of fiber types exist, and there are many different cable configurations, depending on whether the cable is to be installed inside a building, in underground pipes, outside on poles, or under water. --- Basically, a fiber-optic system simply converts an electrical signal to an (infrared) light signal, launches or transmits this light signal onto an optical fiber, and then captures the signal on the other end, where it reconverts it to an electrical signal. Even though miniature or tiny light sources and detectors are in use, optical fibers are so small that special connectors must be used to couple the light from the source to the fiber and from the fiber to the detector. The optical fiber provides a low-loss path for the light to follow from the light source to the light detector. In a sense it is a waveguide that carries optical energy. When the link becomes too long, the fiber will attenuate the lightwaves traveling down it so that the lightwaves cannot be distinguished from noise. Today the range goes to tens of kilometers before amplification is necessary. Even with the highest-intensity light sources and the lowest-loss fibers, the lightwaves finally become so weak or dim from absorption and scattering that they must be regenerated. At this point a repeater must be placed in the circuit. This device consists of a light receiver, pulse amplifier and regenerator and a light source. Together they rebuild the pulses to their former level and send them on their way. Not covered here, but other components one might find in a fiber optic relay system are passive and/or active devices, and connectors and splitters. Tx Rx Amplifier Electrical Optical 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik Verici (transmitter)
Fonksiyon: Elektriksel – Optik dönüşüm (E/O) Tipleri: Light Emitting Diode - LED Laser Diode – LD (FP, DFB) Karşılaştırma: Tx Konu LED LD Veri hızı Düşük Yüksek Mod Multimode Multimode veya single mode Mesafe Kısa Uzun Sıcaklık hassasiyeti Değişken Maliyet Pahalı The transmitter consists of a light source and associated electronic circuitry. The source can be a light-emitting diode (LED) or laser diode. The transmitter electronics are used to set the source operating point and to vary the optical output in proportion to an electrically formatted information input signal. --- The transmitter is physically close to the optical fiber and may even have a lens to focus the light into the fiber. Lasers have more power than LEDs, but vary more with changes in temperature and are more expensive. The most common wavelengths of light signals are 850 nm, 1,300 nm, and 1,550 nm (infrared, non-visible portions of the spectrum). Lifetime of LED’s are on the order of 107 to 108 hours, while that for ILDs are on the order of 106 hours at room temperature. Obviously, none of these devices has been operated for 107 hours, as that represents hundreds of years. In practice, it is rare for a LED or ILD to fail often in a system. They generally will outlast other components such as power supplies and complex circuit board assemblies. Because ILDs in particular use thermoelectric coolers to keep them at constant temperature (generally below room temperature) they are very reliable. There are two laser technologies that are used for nearly all single mode communications applications. At first there are Fabry-Perot (FP) lasers, which are lower in cost, and lower in power but which do have a poorer wavelength stability. The distributed feedback (DFB) lasers have a higher cost, and a higher power level, and offer an excellent wavelength and temperature stability: internally modulated - Good for moderate powers and distances externally modulated - Ultimate today for quality in broadcast applications LED – Light Emitting Diode ILD – Injection Laser Diode 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik güçlendirici (amplifier)
Tanım: Güçlendricili kaplamayla sarılı fiber optik Nasıl Çalışır: laser pump  toplu değişim Çoğu atom yüksüz durum yerine yüklü durumdadır Kontrollü ve uyarılmış yayılım Yüklü atomlar bir foton ile karşılaştığı zaman yeni bir foton oluştururlar, Bu oluşan ikinci foton ilkiyle aynı fazda, frekansta, polarizasyonda ve yönde yaratılır, Bu süreç esnasında ilk foton kaybolmaz, Kullanılan Element erbium – nadir ve pahalı erbium doped fiber amplifier - EDFA Amplifier After an optical signal has travelled a certain distance along a fiber, it becomes greatly weakened due to power loss along the fiber. At that point the optical signal needs to get a power boost. This is done in long-distance links by means of an optical amplifier that boosts the power level completely in the optical domain. In a PON an optical amplifier is not employed in the outside cable plant but is used in a central office to boost the level of analogue video signals before inserting them onto a fiber line. --- An optical amplifier consists of optical fibers with a special coating (doping). The doped portion is "pumped" with a laser. When the degraded signal comes into the doped coating, the energy from the laser allows the doped molecules to become lasers themselves. The doped molecules then emit a new, stronger light signal with the same characteristics as the incoming weak light signal. Basically, the regenerator is a laser amplifier for the incoming signal. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Kendiliğinden ve uyarılmış yayılım
Kendiliğinden yayılım Uyarılmış yayılım 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Üretilen foton (λ signal)
Foton üretimi Dolaşan foton(laser pump) (λ pump) Geçen foton (λ signal) Üretilen foton (λ signal) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Kontollü, uyarılmış yayılım
useful signal laser pump amplified signal 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik alıcı (receiver)
Fonksiyon: Optik – Elektriksel dönüşüm (O/E) Photodetector: APD – Avalanche Photo Diode PIN – Positive Intrinsic Negative photodiode Nasıl çalışır: Işık tarafından uyarıldığında elektriksel sinyal üretir Hatalar: Termal gürültü problemi: ışık sinyalinin algılanabilmesi için yeteri kadar enerji taşıması gerekir Işık sinyallerini yeteri kadar güçlü üretebilirsek hata oranı o kadar azalır Rx Inside the receiver is a photodiode that detects the weakened and distorted optical signal emerging from the end of an optical fiber and converts it to an electrial signal. The receiver also contains electronic amplification devices and circuitry to restore signal fidelity. --- The optical receiver takes the incoming digital light signals, decodes them and sends the electrical signal to the other user's computer, TV or telephone. The receiver uses a photocell or photodiode to detect the light. Semiconductor light sensors (photodetectors) are used to convert the optical energy to electrical current. The detectors most commonly used in fiber optics are positive-intrinsic-negative (PIN) photodiodes and avalanche photodiodes (APDs). As in PON networks most typically a single fiber is used, the device which terminates the optical link is an optical transceiver: this is a single device with both transmitting and receiving functions in a single housing. This is where the main technical difficulty lies: burst mode optics need to be developed which can recover the signal level and bit level timing from multiple end-stations. (See later for a description of burst mode operation) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Alcı-Verici (Transceiver)
Tanım: Aynı modülde hem alıcı hem verici Pratik uygulama: Alıcı-verici modüller SFP olarak adlandırılır Small-Form-factor Pluggable unit Rx Tx As in PON networks most typically a single fiber is used, the device which terminates the optical link is an optical transceiver: this is a single device with both transmitting and receiving functions in a single housing. --- This is where the main technical difficulty lies: burst mode optics need to be developed which can recover the signal level and bit level timing from multiple end-stations. (See later for a description of burst mode operation) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Işık dalgası modülasyonu
dijital Işığın yoğunluğu var/yok modelinde gerçekleşir NRZ - non return to zero 0 – zayıf optik sinyal 1 – güçlü optik sinyal analog Işığın yoğunluğu devamlı olarak değişkenlik gösterir Two types of lightwave modulation are possible: analog or digital. In analog modulation, the intensity of the light beam from the laser or LED is varied continuously. That is, the light source emits a continuous beam of varying intensity. In digital modulation, conversely, the intensity is changed impulsively, in an of/off fashion. The light flashes on and off at an extremely fast rate. In the most typical system – pulse-code modulation PCM – the analog input signals are sampled for wave height. For voice signals this usually at a rate of 8000 times a second. Each wave height is then assigned an 8-bit binary number that is transmitted in a series of individual time slots or slices to the light source. In transmitting this binary number, a 1 can be represented as a pulse of light and a 0 by the absence of light in a specific time slice. Digital modulation is far more popular, as it allows greater transmission distances with the same power than analog modulation. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberler arası bağlantılar
Kalıcı birleştirme EKLER 0.3 dB 0.3 dB 0.1 dB 0.1 dB 0.1 dB 0.1 dB 0.1 dB Terminal A Terminal B CONNECTOR (BİRLEŞTİRİCLER) Ayrılabilir bağlantılar Fiberleri birbirine düşük kayıp verecek yöntemle birleştirin Kalıcı bir bağ mı gerekiyor? – ek yapın (splice)! Söküp-takılabilen esnek bir bağlantı mı? – connector! A significant factor in any fiber optic system installation is the requirement to interconnect fibers in a low-loss manner. These interconnections occur at the optical source, at the photodetector, at intermediate points within a cable where two fibers join, and at intermediate points in a link where two cables are connected. The particular technique selected for joining the fibers depends on whether a permanent bond or an easily demountable connection is desired. A permanent bond (usually within a cable) is referred to as a splice, whereas a demountable joint at the end of a cable is known as a connector. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberleri birleştirmek – Fiber doğrultması
Kötü doğrultma Çekirdekler hizalanmamış Yüksek güç kaybı İyi doğrultma Çekirdekler hizalanmış Düşük güç kaybı 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberleri birleştirmek – Fiber hizalanması
straight physical contact Fazla geri yansıma (büyük) dönüş kaybı angular physical contact Kısmi geri yansıma (küçük) dönüş kaybı In combination with connectors, this becomes: SPC – Straight-Polished Connector APC – Angle-Polished Connector UPC – Ultra-Polished Connector 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberleri birleştirmek – Bağlayıcılar(Konnektör)
özellikler İyi doğrultma/doğru hizalama Fiberin sonlandığı noktada uygulanır Herzaman kaybe neden olur Bağlayıcı(Konnektör) tipleri LC, FC, SC, … Renk kodu APC – yeşil PC – mavi kayıp: 0.3 dB fiber connectors are used when two ends need to be joined and unjoined repeatedly two fibers, or a fiber and an electro-optical source or detector, at fiber terminal equipment, optical patch panels, fiber couplers, … present at the transmitter and receiver interface as a minimum --- LC connectors are used with single-mode and multimode fiber-optic cables. The LC connectors are constructed with a plastic housing and provide for accurate alignment via their ceramic ferrules. LC connectors have a locking tab. LC connectors are rated for 500 mating cycles. FC connectors are used for single-mode and multimode fiber-optic cables. FC connectors offer extremely precise positioning of the fiber-optic cable with respect to the transmitter's optical source emitter and the receiver's optical detector. FC connectors feature a position locatable notch and a threaded receptacle. They have ceramic ferrules and are rated for 500 mating cycles. SC connectors are used with single-mode and multimode fiber-optic cables. They offer low cost, simplicity, and durability. SC connectors provide for accurate alignment via their ceramic ferrules. An SC connector is a push-on, pull-off connector with a locking tab. Typical matched SC connectors are rated for 1000 mating cycles. The ST connector is a keyed bayonet connector and is used for both multimode and single-mode fiber-optic cables. It can be inserted into and removed from a fiber-optic cable both quickly and easily. Method of location is also easy. ST connectors come in two versions: ST and ST-II. These are keyed and spring-loaded. They are push-in and twist types. ST connectors are constructed with a metal housing and are nickel-plated. They have ceramic ferrules and are rated for 500 mating cycles. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Fiberleri birleştirmek – Ekler
Mekanik ek Fiberleri doğrultun ve hizalayın, Sonra birbirine kenetleyin Lehim ek Fiberleri doğruştun ve hizalayın, Sonra fiberleri lehimleyin Elektirsel lehim cihazı kullanın kayıp: 0.1 dB Mechanical splices just lay the two carefully cut ends next to each other on a special sleeve and clamp them in place. Alignment can be improved by passing light through the junction and then making small adjustments to maximize the signal. Mechanical splices take trained personnel about 5 minutes, and result in a 10 percent light loss. Two pieces of fiber can be fused (melted) to form a solid connection. A fusion splice is almost as good as a single drawn fiber, but even here, a small amount of attenuation occurs. For both kinds of splices, reflections can occur at the point of the splice, and the reflected energy can interfere with the signal. --- Fiber-optic cables might have to be spliced together for a number of reasons—for example, to realize a link of a particular length. Another reason might involve backhoe fade, in which case a fiber-optic cable might have been ripped apart due to trenching work. The network installer might have in his inventory several fiber-optic cables, but none long enough to satisfy the required link length. Situations such as this often arise because cable manufacturers offer cables in limited lengths—usually 1 to 6 km. A link of 10 km can be installed by splicing several fiber-optic cables together. The installer can then satisfy the distance requirement and avoid buying a new fiber-optic cable. Splices might be required at building entrances, wiring closets, couplers, and literally any intermediate point between a transmitter and receiver. Connecting two fiber-optic cables requires precise alignment of the mated fiber cores or spots in a single-mode fiber-optic cable. This is required so that nearly all the light is coupled from one fiber-optic cable across a junction to the other fiber-optic cable. Actual contact between the fiber-optic cables is not even mandatory. There are two principal types of splices: fusion and mechanical. Fusion splices use an electric arc to weld two fiber-optic cables together. The process of fusion splicing involves using localized heat to melt or fuse the ends of two optical fibers together. The splicing process begins by preparing each fiber end for fusion. Fusion splicing requires that all protective coatings be removed from the ends of each fiber. The fiber is then cleaved using the score-and-break method. The quality of each fiber end is inspected using a microscope. In fusion splicing, splice loss is a direct function of the angles and quality of the two fiber-end faces. Dış çevrede bulunan fiber eklerinin muhafazası 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik güç ayırıcıları (splitter)
optik splitter … Optik sinyali böler … Tek girişli sinyalden çok (e.g. iki) çıkışlı sinyal Ve genelde olarak Düşük optik güç kaybına sebep verir l1 l2 l1 l3 1 -> 4, 1 -> 8 : planar splitter --- Passive splitters are made by twisting and heating several optical fibers until the power output is evenly distributed. Splitter loss depends on the split ratio and is about 3 dB for a 1 x 2 splitter, increasing by 3 dB each time the number of outputs is doubled. A 1 x 32 splitter has a splitter loss of at least 15 dB. This loss is seen for both downstream and upstream signals. l1 Passive 3 dB kayıp 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik dalgaboyu ayırıcıları (splitter)
wavelength division multiplexing … sağladıkları … Çoklu dalgaboyu (e.g. iki) Tek bir fiberde Yapılan dizayna göre optik dalgaboyu splitterlar … Genel olarak … Çok az güç kaybına sebep olur l1 Optical Wavelength Splitting = kind of FDM, but in optics … and is most typically called WDM: Wavelength Division Multiplexing l1 l2 l2 Passive 0.3 dB loss kayıp 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON - Optik ağlar ve Ağ topolojisi
Point to Point (Noktadan Noktaya) + Yüksek kapasite - Yüksek fiber kurulum maliyeti Active Star (Aktif Yıldız) + Yüksek kapasite - Yüksek bakım ve işletim maliyeti - Yüksek out-door ekipman maliyeti Passive Star (Pasif Yıldız) + Standartlaşmış + Pasif ve esnek kablo kurulumu + Düşük işletim maliyeti + Tüm hizmet tek fiberde + Düşük kurulum maliyeti CO CO CO A (double) ring structure is mostly used in fiber optic networks, at the core of networks, as that is the place where very big capacities are needed. This slide – for FTTx applications Distance – optical power budget Passive Optical Networks (PONs) Shares fiber optic strands for a portion of the networks distribution Uses optical splitters to separate and aggregate the signal Power required only at the ends Active Node Subscribers have a dedicated fiber optic strand Many use active (powered) nodes to manage signal distribution Hybrid PONs Literal combination of an Active and a PON architecture --- ODN = Optical Distribution Network 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

(distribution section)
PON fiber kısımları Birinci Esneklik noktası İkinci Esneklik Noktası CO CP Besleyici kısım (feeder section) İndirme kısmı (drop section) Dağıtım kısmı (distribution section) Merkezi splitter senaryosu Splitterlar sadece birinci esneklik noktasında Dağılmış splitter senaryosu Splitterlar hem birinci hem ikinci esnkelik noktasında CO = Central Office CP = Customer Premises --- PON = Passive Optical Network OSP = OutSide Plant ODN = Optical Distribution Network All of these three abbreviations are more or less the same: they represent what is out in the field between the CO device and the CP device, excluding these devices themselves! 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Merkesi Splitter In a centralised architecture, the splitters are all located in the primary flexibility point. The primary flexibility point is the ODN element where the feeder plant and the distribution plant are cross-connected. As shown in the figure above, the distribution fiber cable includes a separate fiber for each drop. As the distribution fiber passes by a group of houses (for example, a group of four homes), a drop box is used to allow access to the fibers serving the homes in that group. The rest of the fibers remain unbroken and continue down the distribution fiber cable run. While outside plant designs vary widely and generalized rules are difficult to make, centralized splitters tend to provide more flexibility and lower cost in some deployment situations, such as overbuild, where service take rates are lower and not all homes passed are connected (drops and ONTs installed). Homes are connected as broadband services are requested by customers. This allows only the homes that are connected to be patched to splitter ports. All homes passed can be potentially patched to splitters by adding additional splitters, but initially only those homes that are actually connected consume splitter ports. This can be done because the distribution cables converge at the centralized splitters located at the primary flexibility point. Because the number of splitters correlates directly to the number of feeder fibers and OLT PON ports, better splitter port utilization results in fewer feeder links and PON ports in the CO. The centralized scheme can be viewed as more future-proof because it uses direct fiber links from the primary flexibility point to the customers and enables technologies, such as WDM PON. Shorter loop lengths tend to favor centralized schemes because the distributed model’s use of fewer cables results in negligible possible savings. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Dağıtık Splitter Instead of locating all the splitters at the primary flexibility point, it is possible to have splitters in multiple points in a cascading fashion. The figure above shows how the feeder fiber can be split 1:16 ways using splitters located in the primary flexibility point. Each one of the branch fibers in the distribution cable can be further split 1:4 ways in the drop box. Only one fiber is needed to serve a group of homes, instead of dedicated fiber for each home as in the centralized model. The single fiber is split and cross-connected to the drop cables for each home at the drop box. In greenfield situations where all homes passed are connected, a distributed splitter architecture provides better cost points because it can minimize the cost of fiber. For example, if a 1:4 splitter located in the primary flexibility point is feeding a 1:8 splitter in the drop box, only one fiber is required to serve 8 homes up to the drop point and much lower fiber count distribution cable can be used, resulting in lower cost. The limitation in this case, however, is that even if only 1 of the 8 homes is connected, it still needs to be connected back to the 1:4 splitter, which in turn will consume a feeder link and an OLT port back at the CO. The result will be poor utilization and higher cost. In some deployment situations, (particularly with RF overlay) where high transmit launch power is required because of the loop length, a distributed model may offer some advantages by reducing the effect of stimulated Brillouin scattering (SBS). In this case, the first-stage splitters can be located in the CO and can immediately reduce the power level, thus avoiding any possible SBS effect. In either centralized or distributed cases, however, using a higher split ratio of 1:64 provides significant CAPEX savings in the outside plant as well as in CO electronics and passive connectivity. An extra split of 1:64 vs. 1:32 can substantially reduce feeder plant cost an CO electronics and passive connectivity costs. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON Besleyici yedekliliği
ITU-T G standartı OLT – ONT arasında 3 tip yedekliliği tanınmlar Type A : yedek fiber, ek olarak LT ve ya ONT olmadan Type B : yedek splitter : yedekli 2 LT’den ilk splittera kadar yedekli 2 fiber Type C: uçtan uca yedeklilik: yedekli LT, fiber, splitter, ONT

PON Besleyici yedekliliği
Alcatel-Lucent Type B yedekliliği desteklemektedir (Type B-) LT PON’dan optik splittera kadar 1+1 yedekli besleyici fiberler Fiber-only koruması: yedek fiber diğeri kesildiği zaman kullanılır ** Eş zamanlı fiber kesintilerini önlemek için iki besleyici bölüm için iki farklı çoğrafi yol kullanılmalıdır ** LT yedekliliği yok – LT’de oluşacak herhangi bir software ya da hardware arızasına karşı yedeklilik yok LT kapasitesini 50% düşürür PON 1 PON 2 N:2 splitter LT koruma

PON faydaları Tamamen pasif fiber kurulumu
Düşük bakım maliyeti ve yüksek güvenilirlik Tek fiberi bir çok müşteri için paylaşıma sunar Az fiber ihtiyacı, santralde az port kullanımı Sanal olarak fiberde bantgenişliği limitsiz Daha yüksek bantgenişliği x bakır erişime kıyasla daha uzak mesafe Fiberler gelecekte WDM bağlantıları için tekrar değerlendirilebilir Kurulu fiber altyapısı gelecek için bir yatırımdır PON ile tek bir fiberden çoklu hizmet verilebilir triple play – voice / data / video Most networks in the telecommunications networks of today are based on active components at the serving office exchange and termination points at the customer premises as well as in the repeaters, relays and other devices in the transmission path between the exchange and the customer. By active components, we mean devices which require power of some sort, and are generally comprised of processors, memory chips or other devices which are active and processing information in the transmission path. With Passive Optical Networks, all active components between the central office exchange and the customer premises are eliminated, and passive optical components are put into the network to guide traffic based on splitting the power of optical wavelengths to endpoints along the way. This replacement of active with passive components provides a cost-savings to the service provider by eliminating the need to power and service active components in the transmission loop. The passive splitters or couplers are merely devices working to pass or restrict light, and as such, have no power or processing requirements and have virtually unlimited Mean Time Between Failures (MTBF) thereby lowering overall maintenance costs for the service provider. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON kurulum senaryoları – FTTx
FTTEx FTTCab FTTC FTTH/B ONU ADSL ( < 6 KM ) XNT Central Office < 8 Mbit/s ATM NETWORK OLT ONU ADSL/VDSL ( < 1 KM ) XNT LL Network < 26 Mbit/s ONU VDSL ( < 300 M ) OTHER XNT A Passive Optical Network (PON) consists of an optical line terminator (OLT) located at the Central Office (CO) and a set of associated optical network terminals (ONTs) located at the customer’s premise. Between them lies the optical distribution network (ODN) comprised of fibers and passive splitters or couplers. In a PON network, a single piece of fiber can be run from the serving exchange out to a subdivision or office park, and then individual fiber strands to each building or serving equipment can be split from the main fiber using passive splitters / couplers. This allows for an expensive piece of fiber cable from the exchange to the customer to be shared amongst many customers thereby dramatically lowering the overall costs of deployment for fiber to the business (FTTB) or fiber to the home (FTTH) applications. The alternative is to run individual fiber or copper strands from exchange to customer premises, which results in much higher serving costs per customer. --- FITL = Fibre In The Loop The application of PON technology for providing broadband connectivity in the access network to homes, multiple-occupancy units, and small businesses commonly is called fiber-to-the-x. This application is given the designation FTTx. Here x is a letter indicating how close the fiber endpoint comes to the actual user. This is illustrated in the drawing above. Among the acronyms used in the technical and commercial literature are the following: FTTB – fiber-to-the-business, refers to the deployment of optical fiber from a central office switch directly into an enterprise. FTTC – fiber-to-the-curb, describes running optical fiber cables from central office equipment to a communication switch located within 1000 ft (about 300m) of a home or enterprise. Coaxial cable, twisted pair copper wires (e.g. for DSL), or some other transmission medium is used to connect the curbside equipment to customers in a building. FTTH – fiber-to-the-home, refers to the deployment of optical fiber from a central office environment directly into a home. The difference between FTTB and FTTH is that typically, business demand larger bandwidths over greater part of the day than do home users. As a result, a network service provider can collect more revenues from FTTB networks and thus recover the installation costs sooner than for FTTH networks. FTTO – fiber-to-the-office, is analogous to FTTB in that an optical path is provided al the way to the premises of a business subscriber. FTTP – fiber-to-the-premises, has become the prevailing term that encompasses the various FTTx concepts. Thus FTTP architectures include FTTB and FTTH implementations. An FTTP network can use BPON, EPON or GPON technology. FTTU – fiber-to-the-user, is the term used by Alcatel-Lucent to describe their products for FTTB and FTTH applications. FTTx: FTTH – Fibre to the home FTTB – Fibre to the business FTTC – Fibre to the curb FTCab – Fibre to the cabinet FTTEx – Fibre to the exchange FTTP – Fibre to the premises < 52 Mbit/s POTS/ISDN ONT 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

ITU-T GPON standartları
G – GPON hizmet gereksinimleri Hat hızı konfigurasyonunu ve hizmet yeterliliklerini tanımlar G – GPON fizisel ortam Transceiver (alıcı-verici) karakteristiğini tanımlar G – GPON iletim ortamı İletim ortamı protokollerini, fiziksel katman OAM ve mesafe hesaplama mekanizmasını tanımlar G – GPON ONT yönetim kontrol arayüzü (OMCI) GPON paket formatını düzenler In 2001, the FSAN group initiated a effort for standardizing PON networks operating at bit rates above 1 Gbps. Apart from the need to support higher bit rates, the overall protocol had to be opened for reconsideration so that the solution would be most optimal and efficient to support multiple services and operation, administration, maintenance and provisioning (OAM&P) functionality and scalability. As a result of FSAN efforts, a new solution emerged in the optical access market place – Gigabit PON (GPON), offering unprecedented high bit rate support (up to Gbps) while enabling the transport of multiple services, specifically data and TDM, in native formats and with extremely high efficiency. In January 2003, the GPON standards were ratified by ITU-T and are known as ITU-T Recommendations G.984.1, G and G ------ G984.1 provides the GPON framework, and is known as the GPON service requirements (GSR). The GSR summarizes the operational characteristics that service providers expect of the network, in terms of transport speeds, tolerances, delay, etc. G984.2 provides the GPON physical medium dependant specifications (GPS). This includes operational parameters of the optical transmitters and transceivers, clock recovery and error correction mechanisms. G984.3 provides the GPON transmission convergence (GTC) specifications. The GTC is responsible for correct implementation of the data flow process in the physical layer and addresses issues such as the frame structure, the control sequence between the OLT and the ONTs, and the packet encryption function. G984.4 defines the ONT management and control interface (OMCI) for a GPON. ---- G (future GPON λ-bands) G (Reach extension) Alcatel-Lucent kullandığı OMCI metod detaylarını açıklayan ilk firmadır 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

ITU-T G.984.x framework Voice/Data/Video C/M application … … Ethernet
G OMCI OMCI PLOAM G GTC TC adaptation sublayer Framing sublayer Embedded OAM This picture shows the protocol stack for the overall GPON architecture. GPON is required to support all currently known services and new services being for the residential subscribers and business customers. Therefore, the set of G.984 standards describes a flexible access networks using optical fibre technology. The focus is primarily on a network to support services including POTS, data, video, leased line and distributive services. The G concentrates on the physical and fibre aspects (optical considerations, power budgets, rates, etc). G covers the Transmission Convergence (TC) aspects between the service node interface and the user-network interface and deal with specifications for frame format, media access control method, ranging method, OAM functionality and security in G-PON networks. Finally, G specifies the detailed information structure of the ONT Management and Control Interface (OMCI) for the G-PON system to enable multi-vendor interoperability between the OLT and the ONT. G PMD PON-PHY G General characteristics 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON özellikleri PON – Passive Optical Network lambda Mesafe ayarlama
Pasif bileşenler splitters + WDM-aleti Yıldız topoloji p2mp – tek noktadan çok noktaya lambda 1490nm – downstream verisi 1310nm – upstream verisi 1550nm – downstream (opsiyonel) Mesafe ayarlama 60 km mantıksal erişim 20 km fiziksel erişim Mesafe farkı Split oranı 64 kullanıcı (gelecek sürümlerde 128) PON According to the GSR, a GPON must be a full-service network, which means that it should be able to carry all service types. These include 10- and 100-Mbps Ethernet, legacy analog telephone, digital T1/E1 traffic (I.e., and Mbps), 155-Mbps asynchronous transfer mode (ATM) packets, and higher-speed leased-line traffic. The nominal line rates are specified as 1.25 Gbps ( Mbps) and 2.5 Gbps ( Mbps) in the downstream direction, and 155 Mbps, 622 Mbps, 1.25 Gbps, and 2.5 Gbps in the upstream direction. The data rates can be either symmetrical (the same rate in both directions) or asymmetrical, with higher rates being sent downstream from the OLT to the ONTs. A service provider can offer a lower upstream rate to those GPONs in which the downstream traffic is much larger than in the upstream direction, as is the case when subscribers use the IP data service mainly for applications such as lower-rate upstream Internet surfing or and higher-rate downstream downloads of large files. The wavelengths are specified to be in the range 1480 to 1500 nm for downstream voice and data traffic and 1260 to 1360 nm for its corresponding upstream traffic. Thus, the median values are the standard and 1310-nm wavelengths as used in BPON and EPON systems. In addition, the wavelength range 1550 to 1560 nm can be used for downstream video distribution. Depending on the capabilities of the optical transmitters and receivers, the GPON recommendation specifies maximum transmission distances of 10 or 20 km. For a GPON the maximum number of splitting paths is 64. --- The 60 km max. distance is also referred to as a logical distance: this is related to the ranging procedure, where an ONT will add some equalisation delay depending on the distance the ONT is away from the OLT. This leads to all ONTs being virtually away 60 km from the OLT. About the split: the standards already took care of having a split of up to 128 subscribers, which is sometimes referred to as a logical split. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Mesafe hattaki bileşenlerde oluşan kayba göre değişir:
Optik güç bütçesi Mesafe hattaki bileşenlerde oluşan kayba göre değişir: Splitter kaybı Kaskat splitter kullanılabilir e.g. 1:4 ve ardından 1:8 splitter ya da tam tersi Ya da 1:32 tek splitter kullanılabilir WDM coupler kayıpları Fiber kayıpları Konnektör kayıpları Ek kayıpları PON distance = f(loss), splitters WDM coupler fiber ( x dBm/km) splices application (data or video) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Veri alış-veriş özellikleri (class B+)
P (dB) P (dB) +5,0 Downstream bütçesi: +1,5 – (-27) – (0,5) = 28,0 +1,5 1490 nm path penalty: 0,5 dB -8,0 0,30 dB/km Tx level -27,0 Rx level P (dB) P (dB) Tx level Rx level +5,0 0,42 dB/km The loss budget requirement for the PON, based on ITU Recommendation G.983.4, is 22 dB total loss budget for Class B PON and 27 dB for Class C PON. What differentiates Class B and Class C PON is the power of the laser used and, marginally, the quality of the optical components. This loss budget is really tight, especially when high-port-count splitters are used in the design. The splitters in a PON cause an inherent loss because the input power is divided between several outputs. Splitter loss depends on the split ratio and is about 3 dB for a 1 x 2 splitter, increasing by 3 dB each time the number of outputs is doubled. A 1 x 32 splitter has a splitter loss of at least 15 dB. This loss is seen for both downstream and upstream signals. Combine the losses of the WDM coupler, splices, connectors and fiber itself, and it is easy to understand why a precise bidirectional measurement of end-to-end optical loss at the installation is a must. In addition to the optical loss, the end-to-end link optical return loss (ORL) is very important to measure. Undesirable effects of ORL include: Interference with light-source signals Higher bit error rate in digital systems Lower system optical-signal-to-noise ratio Strong fluctuations in the laser output power Permanent damage to the laser Upstream bütçesi: +0,5 – (-28) – (0,5) = 28,0 path penalty: 0,5 dB +0,5 -8,0 1310 nm -28,0 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik güç bütçesi – Veri
örnek: bütçe: 28,0 dBm 16 yönlü splitter kaybı: 13,8 dBm (theor. 12dBm) konnektör+ek kaybı: 3 dBm (24*0,1 dBm + 2*0,3 dBm) Fiber yaşı: 1 dBm zayıflama: 0,30 dBm/km – downstream 0,42 dBm/km – upstream mesafe: (28,0 – 13,8 – 3 – 1) / 0,42 = 10,2 / 0,42 = 24,28 km yorum: 1:16 split için max ONT mesafesi 24 km A system is limited in the distance you can send signals and the maximum number of times you can split the signal to go to different subscribers. The main problem is usually that the signal level drops too low to be usable. Other considerations sometimes dominate. Fiber loss per km is 0.25 dB (1550 nm) to 0.4 dB ( nm) Every time the signal is split two ways, half the power goes one way and half goes the other. So each direction gets half the power, or the signal is reduced by 10log(0.5)=3 dB. Broadcast analog video actually sets the distance (see next slide) --- Class A – 5-20 dB Class B – dB Class C – dB The power budget available (for data) on a particular PON depends on the class of laser used: e.g. for class B+ it is 28 dB The power budget available (for video) on a particular PON is lower than this. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Video alış-veriş özellikleri
P (dB) P (dB) +18,5 Downstream budget: +18,5 – (-4,9) = 23,4 1550 nm Tx level -4,9 Rx level 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Optik güç bütçesi – Video
örnek: bütçe: 23,4 dBm 16 yönlü splitter kaybı: 13,8 dBm (theor. 12dBm) konnektör+ek kaybı: 3 dBm (24*0,1 dBm + 2*0,3 dBm) Fiber yaşı: 1 dBm zayıflama: 0,25 dBm/km - downstream mesafe: (23,4 – 13,8 – 3 – 1)/0,25 = 22,4 km yorum: 1:16 split max ONT mesafesi 22,4 km A system is limited in the distance you can send signals and the maximum number of times you can split the signal to go to different subscribers. The main problem is usually that the signal level drops too low to be usable. Other considerations sometimes dominate. Fiber loss per km is 0.25 dB (1550 nm) to 0.4 dB ( nm) Every time the signal is split two ways, half the power goes one way and half goes the other. So each direction gets half the power, or the signal is reduced by 10log(0.5)=3 dB. Broadcast analog video actually sets the distance (see next slide) --- Class A – 5-20 dB Class B – dB Class C – dB The power budget available (for data) on a particular PON depends on the class of laser used: e.g. for class B+ it is 28 dB The power budget available (for video) on a particular PON is lower than this. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON lambda Tek fiber üzerinde upstream ve downstream video
Ters yönde iki farklı dalgaboyu video Downstream yönünde tek dalgaboyu 1490 nm 1310 nm Data path 1550 nm Video path Splitters Hat hızı esnekliği X Mb/s Y Mb/s Feeder section: stretch from CO to first splitting point Issue: the optical power budget … The loss budget requirement for the PON, based on ITU Recommendation G.983.4, is 22 dB total loss budget for Class B PON and 27 dB for Class C PON. What differentiates Class B and Class C PON is the power of the laser used and, marginally, the quality of the optical components. This loss budget is really tight, especially when high-port-count splitters are used in the design. The splitters in a PON cause an inherent loss because the input power is divided between several outputs. Splitter loss depends on the split ratio and is about 3 dB for a 1 x 2 splitter, increasing by 3 dB each time the number of outputs is doubled. A 1 x 32 splitter has a splitter loss of at least 15 dB. This loss is seen for both downstream and upstream signals. Combine the losses of the WDM coupler, splices, connectors and fiber itself, and it is easy to understand why a precise bidirectional measurement of end-to-end optical loss at the installation is a must. In addition to the optical loss, the end-to-end link optical return loss (ORL) is very important to measure. Undesirable effects of ORL include: Interference with light-source signals Higher bit error rate in digital systems Lower system optical-signal-to-noise ratio Strong fluctuations in the laser output power Permanent damage to the laser 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

PON dalgaboyu planı 1.3 m wavelength band intermediate
upstream upstream/downstream upstream/downstream DATA VIDEO UP Reserved DOWN 1260 1280 1300 1320 1340 1360 1380 1400 1420 1440 1460 1480 1500 1520 1540 1560 l1 l2 l3 l4 Basic band Enhancement band The 1.5 micron band can in general be used for both down as well as upstream communication, and falls apart in 3 sub-bands: basic band: Wavelength region allocated for the ATM-PON downstream capabilities. enhancement band: Wavelength region allocated for new additional service capabilities, which include at least video services and Dense Wavelength Division Multiplexing (DWDM) services. future band: reserved wavelength region for future use. (not shown in slide) --- The wavelengths are specified to be in the range 1480 to 1500 nm for downstream voice and data traffic and 1260 to 1360 nm for its corresponding upstream traffic. Thus, the median values are the standard and 1310-nm wavelengths as used in BPON and EPON systems. In addition, the wavelength range 1550 to 1560 nm can be used for downstream video distribution. Depending on the capabilities of the optical transmitters and receivers, the GPON recommendation specifies maximum transmission distances of 10 or 20 km. For a GPON the maximum number of splitting paths is 64. Upstream Window (no change) Basic band (constrained APON band) Enhancement band (other uses) For future use 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

CTS – Common Technical Specifications
line rate downstream: Gb/s upstream: Gb/s Dalgaboyları downstream data: 1490 nm upstream data: 1310 nm downstream video: 1550 nm PON GPON The nominal line rates for GPON are specified as 1.2 and 2.4 Gbps in the downstream direction and 155 Mbps, 622 Mbps, 1.2 Gbps, and 2.4 Gbps in the upstream direction. The data rates can be either symmetrical (the same rate in both directions) or asymmetrical, with higher rates being sent downstream from the OLT to the ONTs. --- CTS = Common Technical Specifications, a task group created in March 2005. The objective of this task group is to identify the broadest common system specification consensus based on the GPON standard series. The aim is to reduce the number of implementation options and thus ease the implementers work and speed up early order volumes. FSAN telcos participating to the CTS are thinking that such a reduction could decrease dramatically the price of next optical access systems based on GPON. Consequently, this effort is an operator driven process and FSAN vendors will be invited to spot the hard points whenever higher level consensus needs to be met. The first decision taken by the "GPON CTS" Task Group was to give the information that 1.25/2.5Gbps (US/DS) is the preferred linerates combination. Moreover, five operators indicated that they need such a linerate combination with a 20km reach, while two operators have interest in both a 10 and 20km reach and one operator could do with a 10km reach only capable system. A G-PON system operating at 1.25/2.5 Gbps (US/DS) was decided to meet the dual objective for selecting a single linerate combination with sufficient capacity for both business applications and residential applications. Other linerate combinations that are also specified in the ITU-T G.984 G-PON Recommendations continue to remain available for development for additional applications. 2.5 Gbps = Mbps 1.25 Gbps = Mbps 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON protokol katmanları ve formatları
GEM – GPON Encapsulation Method Ethernet + TDM ATM – Asynchronous Transfer Mode [AAL2] + Ethernet + TDM POTS/VF VG Ethernet [AAL5] + Ethernet optical (TDM/TDMA) ONT OLT AAL2 and AAL5 are indicated between square brackets, as they are optional (and actually no-one is implementing ATM) AAL = ATM Adaptation Layer AAL2 = adaptation for e.g. voice (CBR style of connection) AAL5 = adaptation for data --- Depending on who you are talking to, people talk about Generic Encapsulation Method or GPON Encapsulation Method. BAS 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

OMCI – ONT Management Control Interface
ONT’leri OLT üzerinden yönetmek için kullanılan metod Konfigurasyon, hata ve performans yönetimi için Her ONT ve OLT kendi OMCI kanalını kullanır Bantgenişliği PON yaratıldığı anda rezerve edilir protokol OMCI protokolü PON The purpose of OMCI is similar to that of ILMI known from xDSL. OMCI includes configuration, fault and performance management. Capacity: ~424kbps per ONT --- Actually the OMCI channel is a bidirectional channel on the PON for the purpose of managing a single ONT. So on a particular PON there are as many OMCI channels as there are provisioned ONTs, or in other words, each ONT gets it’s own OMCI channel. For the upstream direction of the OMCI channel each ONT gets its own T-CONT, identified by its own unique allocation ID. The allocation ID for the ONT is assigned by the P-OLT, and communicated back to the ONT at the end of the ranging procedure through the downstream PLOAM channel. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Downstream operasyonu (1/2)
TDM – Time Division Multiplexing continuous mode operation (devamlı sinyal verişi) Downstream yönündeki trafik tüm ONT’ler tarafından alınır sorun: data gizliliği AES – Advanced Encryption Standard Link katmanı şifrelemesi Rx l0 Tx Rx l0 The process of transporting data downstream to the customer premises is different from transporting data upstream from the customer premises. Downstream data is broadcasted from the OLT to each ONT, and each ONT processes the data destined to it by matching the address at the protocol transmission unit header. --- When the OLT sends an ATM cell down the PON, each ONT compares the cell's VPath identifier against its own. If there's a match, the ONT copies the cell, removes it from the network, and sends it to the customer premises. Each customer premises then compares the cell's VC identifier against its own, and if there's a match, the node copies the data and removes the cell. Data is transmitted continuously on the downstream using time division multiplexing (TDM), the data is broadcast to all ONUs. Clock and data are extracted and the ONUs may synchronise in the same way as SDH/SONET using specific patterns in an overhead field, or by ATM cell delineation as described in ITU-T recommendation I.432. As is the case with other PON architectures, since the downstream data from the OLT are broadcast to all ONTs, every message transmitted can be seen by all the users attached to the GPON. Thus, the GPON standard describes the use of a security mechanism to ensure that users are allowed to view only the information intended for them. In addition, such a security mechanism ensures that no malicious eavesdropping threat is probable. One example of a point-to-point encryption mechanism is the Advanced Encryption Standard (AES), which is used to protect the information payload of the data field in the GPON frame. t OLT l0 Rx ONU 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Downstream operasyonu (2/2)
ONT’nin sorumluluğu: downstream sinyalinin senkronizasyonu sync-pattern için Saat(sayaç/clock) hesaplaması Kullanılacak verinin filtrelenmesi Header (paketteki başlık bilgisi) belirteçlerine göre ATM – Circuit-ID GEM – Port-ID Rx l0 Tx Rx l0 t OLT l0 Rx ONU 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Upstream operasyonu (1/2)
TDMA – Time Division Multiple Access Anlık iletim yöntemi (burst mode) Upstream yönünde hangi ONT’nin erişim yetkisi alacağına OLT karar verir sorun: olası çarpışma Erişim yetkisi isteği Mesafe belirleme Rx t l0 ONU OLT Tx Upstream traffic is more complicated due to the shared media nature of the ODN. There is a need to coordinate between the transmissions of each of the ONTs to the OLT in order to avoid collisions. Upstream data is transmitted according to control mechanisms in the OLT, using a TDMA (time division, multiple access) protocol, in which dedicated transmission time slots are granted to each individual ONT. The time slots are synchronized so that transmission bursts from different ONTs do not collide. --- When an ONT needs to send information, it waits for the OLT to send a PLOAM cell. Each PLOAM cell has 26 or 27 grants that anyone can read. The ONT checks the data grant number in the PLOAM cell, and when it matches its own, the ONT uses the grants to send the data. The cell is then transmitted upstream. The OLT receiver receives the bits and, using the preamble to recover the clock, reads out the cells and passes them to the ATM switch for delivery onto the provider‘s core network. Besides this, for this scheme to work properly, the ONTs need to be ranged. Actually ranging has two aspects: distance ranging and amplitude ranging. TDMA requires Medium Access Control (MAC) in the OLT in order … - to prevent collisions - to distribute/schedule upstream bandwidth among ONTs TDMA requires burst mode operation of the OLT receiver (and the ONT transmitter) - upstream data bursts are preceded by burst overhead (OH) - burst overhead size: trade-off between complexity of OLT PMD Rx circuitry and upstream channel efficiency Time division multiple access (TDMA) – similar to downstream, with gaps for laser start/stop (guard time) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Upstream operasyonu (2/2)
ONT upstream verisini gönderir P-OLT gönderilen yetkiye göre Uygun zaman geldiği zaman anlık upstream verisini iletir (burst) P-OLT: senkronizasyon Alınan her anlık veri için (upstream burst) Tx l0 Rx Tx l0 t OLT l0 ONU Tx 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Mesafe belirleme – Neden?
20 km 20 km In normal network conditions, ONUs are located at different distances from the OLT. This results in transmission phase differences and the OLT may receive overlapping transmissions from the different ONUs. The PON concept has a specific method for synchronising the ONU transmissions, called ranging. First, an ONU synchronises itself to the downstream frame headers and waits for the ranging window to open. When the window opens, the network enters into the ranging procedure, during which the delay and phase differences between the OLT and all active ONUs are determined. As a result, the ONUs adjust their transmission phases and grants accordingly. The overall ranging scheme is presented in the picture above. The ranging is operated by the OLT, which opens a ranging window between configurable time periods. This means that the OLT sends a ranging grant and stops the traffic in the network and waits for the ONUs to send their ranging PLOAMs. The ranging window should be large enough to cover propagation and processing delays of all the ONUs, including the farthest ONU. The window size can be programmed to support transport distances up to 20 kilometres (B-PON). During the ranging procedure, each active ONU receives a PON-ID from the OLT, which uses the IDs to send data to each ONU individually. Moreover, the OLT measures the arrival phases of the ONU ranging cells, calculates the required equalisation delays and communicates the information to the ONUs. The ONUs adjusts their transmission phases according to the determined values. After initialisation, each active ONU can transmit data according to the given grants. 15 km Çarpışmaları önlemek için eşitleyici geciktirme (equalization delay) yapılır 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON çerçeve formatı ATM-segment (option) downstream frame – 125 us
GEM-segment upstream frame – 125 us ONU1 ONU2 ONU3 ONU4 ONU5 The GPON frame format is specified as part of ITU-T recommendation G.984.3: GTC – GPON transmission convergence. This recommendation is equivalent to layer 2 (the data transmission layer) in the OSI reference model, and besides the GPON frame format also describes the media access control protocol, the ranging scheme, operations and maintenance processes, and the information encryption method. The picture shows the GPON frame format, which has a fixed 125-s length. The frame consists of a physical control block (PCB) and a payload composed of a pure ATM segment and a GEM segment. The PCB section contains the physical layer overhead information to control and manage the network. PCB ATM-cell GEM-packet 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON çerçeve formatı – Downstream
ATM-segment (option) GEM-segment Physical Control Block Psynch Ident PLOAMd BIP PLend PLend US BW Map In the downstream direction the PCBd (physical control block for frames going downstream) contains the following information: a 4-byte frame synchronization field (Psync). a 4-byte segment (Ident) that contains an 8-kHz counter, a dowstream FEC status bit, an encryption key switchover bit, and 8 status bits reserved for further use. a 13-byte downstream physical layer OAM (PLOAMd) message, which handles functions such as OAM-related alarms or threshold crossing alerts. a 1-byte bit interleaved parity (BIP) field, used to estimate the bit error rate. a 4-byte downstream payload length indicator (Plend), which gives the length of the upstream bandwidth (US BW) map and the size of the ATM segment. The Plend field is sent twice for extra redundancy and error robustness. the N x 8-byte US BW map allocates N transmission time slots to the ONTs. 4 bytes 4 bytes 13 bytes 4 bytes 4 bytes N*8 bytes 1 byte 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON çerçeve formatı – Downstream (devamı)
Physical Control Block N*8 bytes Psynch Ident PLOAMd BIP PLend PLend US BW Map AllocID Flag SStart SStop CRC 12 bits 2 bytes 1 byte … AllocID … CRC The US BW map contains N entries associated with N time-slot allocation identifications for the ONTs. As the picture shows, each entry in the US BW map or access structure consists of: a 12-bit allocation identifier (AllocID) that is assigned to an ONT twelve flag bits that allow the upstream transmission of physical layer overhead blocks for a designated ONT (see slide p. 43) a 2-byte start pointer (SStart) that indicates when the upstream transmission window starts. This time is measured in bytes; the beginning of the upstream GTC frame is designated as time zero. a 2-byte stop pointer (SStop) that indicates when the upstream transmission window stops. a 1-byte CRC that provides a 2-bit error detection and 1-bit error correction on the bandwidth allocation field --- The AllocID identifies the T-CONT (Traffic container) The Port-ID identifies the queue on the ONT With a split to 128 users, this actually means 32 alloc-id’s can be assigned to a single ONT! Entry for ONT#1 Entry for ONT#N 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON çerçeve formatı – Downstream (devamı)
US BW Map 3 entries ONT1 slot 75 slot 240 AllocID Start Stop ONT2 slot 280 slot 400 ONT3 slot 430 slot 550 upstream packet timing guard time guard time This slide gives an example of time-slot allocations for three ONTs. Here there are three entries in the US BW map field. The AllocID of the ONTs are 1, 2, and 3 for ONT1, ONT2, and ONT3, respectively. The center part of the picture shows start and stop time slots listed in the downstream US BW map field during which the various ONTs are allowed to transmit. The lower part of the picture shows the general format of the ensuing upstream information stream form the three ONTs. An appropriate guard time is placed between packets from different ONTs. --- So a GPON system allocates time slots for each ONT to ensure that the data of each ONT is received independently at the OLT. A system of pointers is used. The PCB holds the grant bytes/messages, which defines which ONU should use which time-slots/bytes in the upstream frame. This allocation can change frame after frame, so bandwidth is allocated dynamically. slot times: 75 240 280 400 430 550 time ONU1 ONU2 ONU3 ONU4 ONU5 r s t downstream frame upstream frame u v w x y z … grant 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GPON çerçeve formatı – Upstream
ONU1 ONU2 ONU3 ONU4 ONU5 Header Payload PLOu PLOAMu DBRu Upstream GPON traffic consists of successive transmissions from one or more ONTs. As the picture on previous slide illustrates, the particular sequence of frames is based on the transmission time-slot allocations developed by the OLT. To allow proper reception of the individual burst-mode frames, a certain amount of burst-overhead is needed at the start of an ONT upstream burst. The slide on this page shows the format of an upstream frame, which consists of up to four types of PON overhead fields and a variable-length user data payload that contains a burst of transmission. The upstream header fields are the following: the physical layer overhead (PLOu) at the start of an ONT upstream burst contains the preamble, which ensures proper physical layer operation (e.g., bit and byte alignments) of the burst-mode upstream link. the upstream physical layer operation, administration and management (PLOAMu) field is responsible for management functions such as ranging, activation of an ONT, and alarm notifications. The 13-byte PLOAMu contains the PLOAM message as defined in G and is protected against bit errors by a cyclic redundancy check (CRC) that uses a standard polynomial error detection and correction code. the dynamic bandwidth report (DBRu) field informs the OLT of the queue length of each AllocID at an ONT. This allows the OLT to enable proper operation of the dynamic bandwidth allocation process. The DBRu is protected against bit errors by a CRC. Transmission of the PLOAMu, PLSu, and DBRu fields are optional depending on the downstream flags in the US BW map. Physical layer overhead Physical layer OAM Dynamic bandwidth report 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

GEM encapsulation (paketleme)
GEM = GPON Encapsulation Method GEM allows for point-to-point (noktadan noktaya) payload fragmentasyonu (etkinlik) GEM, TDM transport yapısını destekler E1/T1, E3/T3 TDM GEM header PLI PortID PTI CRC payload payload L bytes 12 bits 12 bits 3 bits 13 bits L bytes Ethernet Payload MACDA MACSA Type/ Length FCS To accommodate all types of services (e.g. ATM, TDM, and Ethernet) efficiently, a GPON encapsulation method (GEM) is used. This method is based on a slightly modified version of the ITU-T recommendation G.7041 Generic Framing Procedure, which gives the specifications for sending IP packets over SONET or SDH networks. --- The GPON encapsulation method works similar to ATM, but is uses variable-length frames instead of fixed-length cells as in ATM. Thus, GEM provides a generic means to send different services over a GPON. The encapsulated payload can be up to 1500 bytes long. If an ONT has a packet to send that is larger than 1500 bytes, the ONT must break the packet into smaller fragments that fit into the allowed payload length. The destination equipment is responsible for reassembling the fragments into the original packet format. The picture above shows the GEM segment structure, which consists of four header fields and a payload that is L bytes long. The header fields are the following: A 12-bit payload length indicator (PLI) that gives the length in bytes of the GEM-encapsulated payload. A 12-bit port identification number that tells which service flow this fragment belongs to. A 3-bit payload type indicator which specifies if the fragment is the end of a user datagram, if the traffic flow is congested, or if the GEM payload contains OAM information. A 13-bit cyclic redundancy check for header error control that enables the correction of two erroneous bits and the detection of three bit erros in the header A key advantage of the GEM scheme is that it provides an efficient means to encapsulate and fragment user information packets. The reason for using encapsulation on a GPON is that it allows proper management of the multiple service flows from different ONTs that share a common optical fiber transmission link. The purpose of fragmentation is to send packets from a user efficiently regardless of their size and to recover the original packet format reliably from the physical layer transmission windows on the GPON. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Devamlı Sinyal Verişi (Continuous mode operation)
downstream frame Tx Rx continuous mode Tx continuous mode Rx downstream – herzaman sinyal vardır Gönderecek kullanıcı verisi olmasa bile Yönetimsel olarak port kapatılmadığı durumlarda components: continuous mode transmitter no need to adapt power level continuous mode receiver clock extraction … Power level consideration In continuous mode operation, the power level is high enough to reach all subscribers. Each ONT gets this signal, although attenuated differently because they all are at different distances from the central office. Anyhow, the attenuation shouldn’t be too big, so there still is enough power in the signal left. The attenuation shouldn’t be too small neither, because then the power level of the singal going out of the fiber would be too big and this might damage the optical receiver. When the power level is in the dynamic range of the receiver, the ONT can easily do the clock extraction and pick up the data destined for him. 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

Anlık Veri Akışı (Burst mode operation)
upstream frame Rx Tx burst mode Rx burst mode Tx upstream – sadece ONT veri ileteceği zaman sinyal vardır Veri iletecek hiç ONT yoksa, fiber üzerinde sinyal olmaz Ardışık 2 anlık veri akışı için koruma zamanı 26ns. components: burst mode transmitter can adapt it’s power level burst mode receiver resync on every single burst coming in the phase of every single data unit is different measure power level of 1 and 0 the amplitude of every single data unit is different  burst overhead Power level consideration Assume all ONTs send their upstream data using the same power level. Due to the fact they are all at different distances, the attenuation imposed will be different for all of them. It even is possible that the power level of a logic 0 from a near ONT exceeds the power level of a logic 1 from a far ONT! So the receiver at the OLT has a hard time to distinguish a logical 1 from a logical 0. In order to do that, the receiver has to measure the power levels of a 0 and a 1 (amplitude ranging), and adapt the detection thresholds accordingly. And this has to happened for each burst coming in! That’s the reason why every burst of information is prepended with some bits/bytes referred to as burst overhead (BO). --- The transmitter operates in burst mode. It has three modes: no light, logic 0 and logic 1. In contrast to point-to-point systems, ONUs which are not permitted to transmit must turn off their lasers. At the input to the OLT’s receiver, the light corresponding to a logic 0 from a near ONU could well exceed the light corresponding to a logic 1 from a far ONU. (chapter 60/4 of Telecommunicatios engineer’s reference book, second edition) 3FL AAAA WBZZA ED © 2009 Alcatel-Lucent., All rights reserved

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