Kuhlelo lwe-EPON, iOLTixhunywe kokuningiAma-ONU(amayunithi enethiwekhi yokubona) nge-POS (i-passive optical splitter). Njengomongo we-EPON,OLTamamojula optical azothinta ngqo ukusebenza kwalo lonke uhlelo lwe-10G EPON.
1.Isingeniso ku-10G EPON symmetricalOLTimodeli ye-optical
I-10G EPON i-symmetricalOLTimojula ye-optical isebenzisa i-uplink burst reception kanye ne-downlink eqhubekayo yokudlulisela izindlela, ezisetshenziselwa ikakhulukazi ukuguqulwa kwe-optical / kagesi ezinhlelweni ze-10G EPON.
Ingxenye etholayo iqukethe i-TIA (i-transimpedance amplifier), i-APD (Avalanche Photodiode) ku-1270 / 1310nm, kanye nama-LA amabili (ama-amplifiers akhawulela) ku-1.25 kanye ne-10.3125 Gbit / s amanani.
Isiphetho sokudlulisa sakhiwe i-10G EML (i-electro-absorption modulation laser) kanye ne-1.25 Gbit / s DFB (i-laser yempendulo esabalalisiwe), futhi ubude bayo bokuphuma bungu-1577 no-1490nm, ngokulandelana.
Isifunda sokushayela sihlanganisa isekethe yedijithali ye-APC (Automatic Optical Power Control) kanye nesekhethi ye-TEC (Isinxephezelo Sezinga lokushisa) ukuze kugcinwe ubude begagasi obuzinzile be-laser engu-10G. Ukuqapha kwepharamitha yokudlulisa nokwamukela kusetshenziswa i-chip microcomputer eyodwa ngokuya ngephrothokholi ye-SFF-8077iv4.5.
Ngoba ukuphela kokuthola kweOLTimojula ye-optical isebenzisa ukwamukela okuqhume, isikhathi sokusetha ukwamukela sibaluleke kakhulu. Uma isikhathi sokumisa ukwamukela siside, sizothinta kakhulu ukuzwela, futhi kungase kubangele ngisho nokwamukela ukuqhuma ukungasebenzi kahle. Ngokwezimfuneko zephrothokholi ye-IEEE 802.3av, isikhathi sokusungulwa kwesamukeli sokuqhuma esingu-1.25Gbit / s kufanele sibe u-<400 ns, futhi ukuzwela kokwamukela ngokuqhume kufanele kube ngu-<-29.78 dBm ngephutha elincane elingu-10-12; kanye no-10.3125 Gbit / s Isikhathi sokusetha ukwamukela okuqhume kufanele sibe ngu-<800ns, futhi ukuzwela kokwamukela ngokuqhuma kufanele kube ngu-<-28.0 dBm ngesilinganiso sephutha esincane esingu-10-3.
2.10G EPON symmetricalOLToptical module design
2.1 Uhlelo lokuklama
I-10G EPON i-symmetricalOLTimojula ye-optical yakhiwa i-triplexer (i-single-fiber yendlela-ntathu module), ukudlulisa, ukwamukela, nokuqapha. I-triplexer ihlanganisa ama-lasers amabili kanye nomtshina. Ukukhanya okudlulisiwe kanye nokukhanya okutholiwe kuhlanganiswe kudivayisi ye-optical ngokusebenzisa i-WDM (Wavelength Division Multiplexer) ukuze kuzuzwe ukudluliswa kwe-bidirectional ye-fiber eyodwa. Ukwakheka kwayo kuboniswe kuMfanekiso 1.
Ingxenye yokudlulisa iqukethe ama-lasers amabili, umsebenzi wawo oyinhloko ukuguqula izimpawu zikagesi ze-1G ne-10G zibe amasignali optical, ngokulandelanayo, nokugcina ukuqina kwamandla okukhanya esimweni esivaliwe se-loop ngokusebenzisa isifunda se-APC yedijithali. Ngesikhathi esifanayo, i-single-chip microcomputer ilawula ubukhulu be-modulation yamanje ukuze ithole isilinganiso sokuqothulwa esidingwa uhlelo. Umjikelezo we-TEC wengezwe kumjikelezo wokudlulisa we-10G, ozinza kakhulu ubude be-wavelength be-laser ye-10G. Ingxenye eyamukelayo isebenzisa i-APD ukuguqula isignali yokubona yokuqhuma etholiwe ibe isignali kagesi, futhi iyikhiphe ngemva kokukhulisa nokubunjwa. Ukuze uqinisekise ukuthi ukuzwela kungafinyelela ebangeni elifanele, kuyadingeka ukunikeza ukucindezela okuphezulu okuzinzile ku-APD emazingeni okushisa ahlukene. Ikhompyutha ye-chip eyodwa ifinyelela lo mgomo ngokulawula isekethe ye-APD high-voltage.
2.2 Ukuqaliswa kokwamukela ukuqhunyiswa kwezilinganiso ezimbili
Ingxenye etholayo ye-symmetric ye-10G EPONOLTimojuli ye-optical isebenzisa indlela yokwamukela ngokuqhuma. Idinga ukwamukela amasiginali wokuqhuma wamanani amabili ahlukene we-1.25 kanye ne-10.3125 Gbit / s, okudinga ingxenye eyamukelayo ukuthi ikwazi ukuhlukanisa amasignali okubonayo alawa manani amabili ahlukene kahle ukuze ithole amasiginali kagesi aphumayo azinzile. Izikimu ezimbili zokuqalisa ukwamukelwa kokuqhuma kwezilinganiso ezimbili zeOLTamamojula optical ahlongozwayo lapha.
Ngenxa yokuthi isignali yokubona okokufaka isebenzisa ubuchwepheshe be-TDMA (Time Division Multiple Access), isilinganiso esisodwa kuphela sokukhanya okungase sibe khona ngesikhathi esifanayo. Isignali yokufaka ingahlukaniswa kusizinda sokubona nge-1: 2 isihlukanisi se-optical, njengokuboniswa kumfanekiso 2. Noma sebenzisa kuphela umtshina wesivinini esiphezulu ukuze uguqule amasiginali we-1G kanye ne-10G optical abe amasignali kagesi abuthakathaka, bese uhlukanisa ezimbili zikagesi. amasignali anamanani ahlukene nge-TIA yomkhawulokudonsa omkhulu, njengoba kuboniswe kuMfanekiso 3.
Uhlelo lokuqala oluboniswe kuMfanekiso 2 luzoletha ukulahlekelwa okuthile kokufaka lapho ukukhanya kudlula ku-1: 2 isihlukanisi se-optical, okumele sikhulise isignali ye-optical input, ngakho-ke i-amplifier optical ifakwe phambi kwe-splitter optical. Amasignali ahlukanisiwe optical abe esengaphansi kokuguqulwa kwe-optical/electrical yizitholi zamazinga ahlukene, futhi ekugcineni kutholakala izinhlobo ezimbili zokuphuma kwesignali kagesi ezinzile. Ukungalungi okukhulu kwalesi sixazululo ukuthi i-amplifier optical kanye ne-1: 2 optical splitter isetshenziswa, futhi ama-detectors amabili ayadingeka ukuze kuguqulwe isignali ye-optical, okwandisa ubunzima bokuqaliswa nokwandisa izindleko.
Ohlelweni lwesibili olukhonjiswe ku-FIG. 3, isignali ye-optical yokufaka idinga kuphela ukudlula kumtshina kanye ne-TIA ukuze kuzuzwe ukuhlukana esizindeni sikagesi. Umnyombo walesi sixazululo usekukhethweni kwe-TIA, okudinga ukuthi i-TIA ibe nomkhawulokudonsa ongu-1 ~ 10Gbit / s, futhi ngesikhathi esifanayo i-TIA inempendulo esheshayo ngaphakathi kwalo mkhawulokudonsa. Kuphela ngepharamitha yamanje ye-TIA engathola inani lokuphendula ngokushesha, ukuzwela kokwamukela kungaqinisekiswa kahle. Lesi sixazululo sinciphisa kakhulu inkimbinkimbi yokuqaliswa futhi sigcina izindleko zilawulwa. Kumklamo wangempela, ngokuvamile sikhetha isikimu sesibili ukuze sizuze ukwamukela okuqhume okukabili.
2.3 Idizayini yesekethe yehadiwe ekugcineni kokwamukela
Umdwebo 4 umjikelezo wehadiwe wengxenye yokwamukela eqhumayo. Uma kukhona okokufaka kwe-optical yokuqhuma, i-APD iguqula isignali yokubona ibe isignali kagesi ebuthakathaka futhi iyithumele ku-TIA. Isignali ikhuliswa yi-TIA ibe isignali kagesi eyi-10G noma engu-1G. Isignali kagesi ye-10G ifakwa ku-10G LA ngokuhlangana okuhle kwe-TIA, futhi isignali kagesi ye-1G ifakwa ku-1G LA ngokuhlanganisa okunegethivu kwe-TIA. Ama-Capacitor C2 kanye ne-C3 angama-coupling capacitor asetshenziselwa ukuzuza okukhiphayo okuhlanganisiwe kwe-10G ne-1G AC. Indlela ye-AC-coupled yakhethwa ngoba ilula kunendlela ye-DC-coupled.
Kodwa-ke, ukuxhuma kwe-AC kunenkokhelo nokukhishwa kwe-capacitor, futhi isivinini sokuphendula esignali sithinteka ngokukhokhiswa nokukhipha isikhathi njalo, okungukuthi, isignali ayikwazi ukuphendulwa ngesikhathi. Lesi sici nakanjani sizolahlekelwa inani elithile lesikhathi sokumisa ukwamukela, ngakho-ke kubalulekile ukukhetha ukuthi inkulu kangakanani i-AC coupling capacitor. Uma i-coupling capacitor encane ikhethiwe, isikhathi sokumisa singafinyezwa, futhi isignali idluliselweI-ONUngesikhathi ngasinye slot ingamukelwa ngokuphelele ngaphandle kokuthinta umphumela wokwamukela ngoba isikhathi sokumisa ukwamukelwa side kakhulu kanye nokufika kwe-slot yesikhathi esilandelayo.
Kodwa-ke, i-capacitance encane kakhulu izothinta umphumela wokuhlanganisa futhi inciphise kakhulu ukuzinza kokwamukela. I-capacitance enkulu inganciphisa i-jitter yesistimu futhi ithuthukise ukuzwela kwesiphetho sokwamukela. Ngakho-ke, ukuze ucabangele isikhathi sokumisa ukwamukela kanye nokuzwela kokwamukela, ama-coupling capacitor afanelekile C2 kanye ne-C3 adinga ukukhethwa. Ukwengeza, ukuze kuqinisekiswe ukuzinza kwesignali kagesi yokufaka, i-coupling capacitor kanye ne-resistor ehambisanayo enokumelana kwe-50Ω ixhunywe ku-terminal negative ye-LA.
Isifunda se-LVPECL (Low Voltage Positive Emitter Coupling Logic) esakhiwe ngezinto eziphikisayo u-R4 no-R5 (R6 no-R7) kanye nomthombo kagesi ongu-2.0 V DC ngokusebenzisa isignali ephumayo ehlukile ngo-10G (1G) LA. isignali kagesi.
2.4 Isigaba sokwethula
Ingxenye yokudlulisa ye-symmetric ye-10G EPONOLTimojula ye-optical ihlukaniswe ikakhulukazi izingxenye ezimbili ze-1.25 kanye ne-10G yokudlulisa, ngokulandelanayo ithumela amasignali nge-wavelength ye-1490 ne-1577 nm ku-downlink. Ukuthatha ingxenye yokudlulisa ye-10G njengesibonelo, i-pair of 10G yezimpawu zokuhlukanisa ingena ku-CDR (Clock Shaping) chip, i-AC-ihlanganiswe ne-chip yomshayeli we-10G, futhi ekugcineni ifaka ngokuhlukile ku-laser ye-10G. Ngenxa yokuthi ukuguqulwa kwezinga lokushisa kuzoba nomthelela omkhulu ku-wavelength ekhishwa yi-laser, ukuze kuzinze ubude begagasi bufinyelele ezingeni elidingwa yi-protocol (iphrothokholi idinga i-1575 ~ 1580nm), ukusebenza kwamanje kwesekethe ye-TEC kudinga ukulungiswa, ukuthi ubude be-wavelength obuphumayo bungakwazi ukulawulwa kahle.
3. Imiphumela yokuhlolwa nokuhlaziya
Izinkomba zokuhlola eziyinhloko ze-symmetric ye-10G EPONOLTimojula ye-optical ihlanganisa isikhathi sokusetha umamukeli, ukuzwela kowamukelayo, kanye nomdwebo weso lokudlulisa. Izivivinyo eziqondile zimi kanje:
(1) Thola isikhathi sokusetha
Ngaphansi kwendawo evamile yokusebenza ye-uplink burst optical power of -24.0 dBm, isignali yokubona ekhishwa umthombo wokukhanya oqhumayo isetshenziswa njengendawo yokuqala yokulinganisa, futhi imojula ithola futhi imise isignali kagesi ephelele njengendawo yokugcina yokulinganisa, indiva ukubambezeleka kwesikhathi sokukhanya ku-fiber yokuhlola.Isikhathi sokusetha esilinganisiwe se-1G burst reception singu-76.7 ns, esihlangabezana nezinga lamazwe ngamazwe elingu-<400 ns; isikhathi sokusetha ukwamukelwa kwe-10G eqhumayo ngu-241.8 ns, futhi ehlangabezana nezinga lamazwe ngamazwe elingu-<800 ns.
3. Imiphumela yokuhlolwa nokuhlaziya
Izinkomba zokuhlola eziyinhloko ze-symmetric ye-10G EPONOLTimojula ye-optical ihlanganisa isikhathi sokusetha umamukeli, ukuzwela kowamukelayo, kanye nomdwebo weso lokudlulisa. Izivivinyo eziqondile zimi kanje:
(1) Thola isikhathi sokusetha
Ngaphansi kwendawo evamile yokusebenza ye-uplink burst optical power of -24.0 dBm, isignali yokubona ekhishwa umthombo wokukhanya oqhumayo isetshenziswa njengendawo yokuqala yokulinganisa, futhi imojula ithola futhi imise isignali kagesi ephelele njengendawo yokugcina yokulinganisa, indiva ukubambezeleka kwesikhathi kokukhanya ku-fiber yokuhlola. Isikhathi esilinganisiwe sokwamukela ukuqhuma kwe-1G singu-76.7 ns, esihlangabezana nezinga lamazwe ngamazwe elingu-<400 ns; isikhathi sokusetha ukwamukelwa kwe-10G eqhumayo ngu-241.8 ns, futhi ehlangabezana nezinga lamazwe ngamazwe elingu-<800 ns.
