Fiber mus rau Lub Tsev (FTTH) tau pib ua tiag tiag los ntawm cov tuam txhab kev sib txuas lus thoob ntiaj teb, ua kom cov thev naus laus zis los txhim kho sai. Active optical networks (AON) thiab passive optical networks (PON) yog ob lub tshuab loj uas ua rau FTTH broadband sib txuas tau. PON uas tuaj yeem muab cov kev daws teeb meem zoo tshaj plaws muaj ntau dua nyob rau hauv feem ntau ntawm FTTH xa tawm. ABC ntawm PON yuav raug qhia hauv tsab xov xwm no, uas feem ntau suav nrog cov khoom siv yooj yim thiab lwm yam cuab yeej suav nrogOLT, ONT, ONU, thiab ODN.
PON piav qhia: txhais, qauv, thiab qhov zoo
Passive optical network yog hais txog fiber ntau-optic network siv lub point-to-multipoint topology thiab optical splitters xa cov ntaub ntawv los ntawm ib qho kev xa mus rau ntau tus neeg siv qhov kawg. Nyob rau hauv sib piv rau AON, ntau tus neeg muas zaub tau txuas nrog ib tug tib transceiver los ntawm txoj kev ntawm ib tug ceg ntoo ntawm fibers thiab passive splitter / combiner units, ua hauj lwm tag nrho nyob rau hauv lub optical domain thiab tsis muaj hwj chim nyob rau hauv ib tug PON architecture. Muaj ob qhov qauv PON tseem ceeb tam sim no: Gigabit Passive Optical Network (GPON) thiab Ethernet Passive Optical Network (EPON). Lawv cov qauv topology yeej ib txwm zoo ib yam. Raws li thawj qhov kev xaiv hauv ntau qhov xwm txheej FTTH xa tawm, PON kev daws teeb meem muaj ntau yam txiaj ntsig zoo:
Kev siv hluav taws xob qis dua
Tsawg Yuav Tsum Tau Qhov Chaw
Siab dua Bandwidth
Kev ruaj ntseg siab dua
Yooj yim rau nruab thiab nthuav
Txo cov nqi khiav lag luam thiab kev tswj xyuas
PON Structure thiab Cheebtsam
Hauv Gigabit Ethernet Passive Optical Network (GEPON) system, muaj cov kab hluav taws xob kho qhov muag (OLT) ntawm cov chaw muab kev pabcuam hauv nruab nrab thiab ntau qhov chaw kho qhov muag (ONUs) lossis optical network terminals (ONTs) nyob ze cov neeg siv kawg, thiab. raws li qhov kho qhov muag splitter (SPL). Tsis tas li ntawd, optical distribution network (ODN) kuj tseem siv tau thaum lub sijhawm sib kis ntawm OLT thiab ONU / ONT.
Optical Line Terminal (OLT)
OLT yog qhov pib taw tes rau qhov kev siv qhov muag tsis pom kev, uas txuas nrog lub hauv paus hloov los ntawm Ethernet cables. Lub luag haujlwm tseem ceeb ntawm OLT yog hloov pauv, thav duab, thiab xa cov teeb liab rau PON network thiab tswj xyuas qhov kho qhov muag network terminals multiplexing rau kev sib koom ua ke sib kis. Feem ntau, OLT cov cuab yeej muaj khib, CSM (Control thiab Hloov Module), ELM (EPON Txuas Module, PON daim npav), kev tiv thaiv rov ua dua -48V DC fais fab mov modules lossis ib qho 110/220V AC fais fab mov module, thiab kiv cua . Nyob rau hauv cov khoom no, daim npav PON thiab cov khoom siv hluav taws xob txhawb kev sib pauv kub thaum lwm tus qauv tsim hauv. OLT muaj ob txoj kev taw qhia ntab dej: sab sauv (muab faib ntau hom ntaub ntawv thiab lub suab tsheb khiav los ntawm cov neeg siv) thiab nqes dej (tau txais cov ntaub ntawv, suab, thiab video tsheb los ntawm metro network lossis los ntawm lub network ntev thiab xa mus rau txhua ONT modules ntawm ODN.) Qhov kev ncua deb tshaj plaws txhawb kev xa tawm thoob plaws ODN yog 20 km.
Optical Network Unit (ONU) / Optical Network Terminal (ONT)
ONU hloov cov teeb liab kho qhov muag kis ntawm fibers mus rau cov teeb liab hluav taws xob. Cov teeb liab hluav taws xob no raug xa mus rau cov neeg siv khoom ib leeg. Feem ntau, muaj kev ncua deb lossis lwm yam kev nkag mus rau hauv lub network ntawm ONU thiab cov neeg siv khoom kawg. Tsis tas li ntawd, ONU tuaj yeem xa, sib sau ua ke, thiab tu cov ntaub ntawv sib txawv los ntawm tus neeg siv khoom thiab xa nws mus rau OLT. Grooming yog txheej txheem uas optimizes thiab reorganizes cov ntaub ntawv kwj ces nws yuav xa tau zoo dua. OLT txhawb nqa kev faib tawm bandwidth uas tso cai rau kev xa cov ntaub ntawv ntab mus rau OLT, uas feem ntau tuaj txog ntawm cov neeg siv khoom tawg. ONU tuaj yeem txuas tau los ntawm ntau txoj hauv kev thiab cable hom, xws li twisted-pair tooj liab hlau, coaxial cable, optical fiber, lossis los ntawm Wi-nkaus.
Cov neeg siv khoom kawg kuj tseem raug xa mus rau qhov chaw siv kho qhov muag (ONT). Qhov tseeb, ONT yog tib yam li ONU hauv cov ntsiab lus. ONT yog lub sij hawm ITU-T, qhov ONU yog lub sij hawm IEEE. Raws li cov qauv sib txawv, lawv ob leeg xa mus rau cov neeg siv khoom siv sab hauv hauv GEPON system. Tab sis hauv kev xyaum, muaj qhov sib txawv me ntsis ntawm ONT thiab ONU raws li lawv qhov chaw nyob.
Optical Distribution Network (ODN)
ODN, ib feem tseem ceeb ntawm PON system, muab qhov nruab nrab kis tau tus mob rau lub cev sib txuas ntawm ONUs rau OLTs nrog 20 km lossis deb dua. Nyob rau hauv ODN, fiber optic cables, fiber optic connectors, passive optical splitters, thiab auxiliary Cheebtsam koom tes nrog ib leeg. ODN tshwj xeeb muaj tsib ntu uas yog feeder fiber, optical tis point, faib fiber ntau, optical access point, thiab poob fiber ntau. Lub feeder fiber yog pib los ntawm optical tis ncej (ODF) nyob rau hauv lub hauv paus chaw ua hauj lwm kev sib txuas lus chav tsev thiab xaus ntawm lub optical tis taw tes rau kev pab nyob rau hauv ntev. Kev faib khoom fiber ntau los ntawm qhov chaw faib khoom kho qhov muag mus rau qhov chaw nkag mus rau qhov muag pom tau faib cov khoom siv kho qhov muag rau thaj chaw ib sab. Qhov poob fiber ntau txuas qhov chaw nkag mus rau qhov chaw txuas mus rau terminals (ONTs), ua tiav cov fiber ntau poob rau hauv cov neeg siv tsev. Tsis tas li ntawd, ODN yog txoj hauv kev tseem ceeb rau PON cov ntaub ntawv xa mus thiab nws qhov zoo cuam tshuam ncaj qha rau kev ua haujlwm, kev ntseeg siab, thiab kev ua kom muaj zog ntawm PON system.
Xaus
OLT, ONU lossis ONT, thiab ODN yog cov khoom tseem ceeb hauv GEPON system, uas tau siv dav hauv FTTH daim ntawv thov nyob deb. Qhov txo qis hauv kev tsim kho kab ke (tsis muaj cov ntsiab lus nquag) thiab kev sib kis tau yooj yim ua rau muaj kev sib txuas lus kho qhov muag zoo tshaj plaws rau kev siv Internet, suab, thiab video. Tsis tas li ntawd, passive optical networks kuj tuaj yeem siv rau hauv cov tsev kawm ntawv qib siab thiab cov chaw lag luam, muab cov kev daws teeb meem zoo. Raws li PON thev naus laus zis tau txuas ntxiv txhim kho, cov ntawv thov muaj peev xwm tau nthuav dav thiab.
