1.1 Passive optical splitter
Passive optical splitter yog ib qho tseem ceeb ntawm PON network.Kev ua haujlwm ntawm passive optical splitter yog faib lub zog kho qhov muag ntawm ib qho kev tawm tswv yim kho qhov muag rau hauv ntau qhov kev tawm.Feem ntau, lub splitter ua tiav lub teeb tawg ntawm 1: 2 txog 1: 32 lossis txawm 1: 64.Tus yam ntxwv ntawm passive optical splitter yog tias nws tsis xav tau lub hwj chim mov thiab muaj zog ib puag ncig adaptability.Txij li thaum EPON upstream channel yog lub sij hawm faib multiplexed los ntawm txhua tusONUs, txhua ONU tuaj yeem xa cov ntaub ntawv tsis pub dhau lub sijhawm teev tseg.Yog li ntawd, EPON upstream channel xa cov teeb liab tawg, uas yuav tsum tau siv cov khoom siv kho qhov muag uas txhawb nqa cov teeb liab tawg hauv ONUs thiab OLTs.
Passive optical splitters nyob rau hauv PON tes hauj lwm feem ntau muab faib ua ob hom: cov tsoos fusion taper splitter thiab cov tshiab tawm tshiab planar optical waveguide splitter.
1.2 Lub cev topology
Lub EPON network txais ib qho point-to-multipoint topology qauv es tsis txhob ntawm ib tug point-to-point qauv, uas zoo heev txuag tus nqi ntawm optical fiber thiab kev tswj cov nqi.PONOLTcov khoom siv txo cov lasers xav tau los ntawm lub hauv paus chaw ua haujlwm, thiab OLT tau qhia los ntawm ntau tus neeg siv ONU.Tsis tas li ntawd, EPON siv Ethernet thev naus laus zis thiab qauv Ethernet thav duab los nqa cov kev pabcuam tseem ceeb tam sim no-IP kev pabcuam yam tsis muaj kev hloov pauv.
1.3 Burst synchronization ntawm EPON lub cev txheej
Txhawm rau txo tus nqi ntawm ONU, cov thev naus laus zis tseem ceeb ntawm covEPONLub cev txheej yog tsom rau ntawm OLT, suav nrog: synchronization sai ntawm cov teeb liab tawg, kev sib txuas hauv network, kev tswj fais fab ntawm optical transceiver modules, thiab kev txais tos txais zoo.
Txij li thaum lub teeb liab tau txais los ntawm OLT yog lub teeb liab tawg ntawm txhua ONU, OLT yuav tsum muaj peev xwm ua tiav theem synchronization hauv lub sijhawm luv, thiab tom qab ntawd tau txais cov ntaub ntawv.Tsis tas li ntawd, vim hais tias lub uplink channel txais TDMA hom, thiab 20km optical fiber ntau kis tau tus mob ncua sij hawm them nyiaj siv tshuab paub txog lub sij hawm qhov synchronization ntawm tag nrho cov network, cov ntaub ntawv packets tuaj txog ntawm lub sij hawm qhov kev txiav txim los ntawm OBA algorithm.Tsis tas li ntawd, vim muaj qhov sib txawv ntawm txhua ONU los ntawm OLT, rau qhov tau txais module ntawm OLT, lub zog ntawm lub sijhawm sib txawv ntawm qhov sib txawv.Hauv DBA daim ntawv thov, txawm tias lub zog ntawm tib lub sijhawm sib txawv, uas yog hu ua qhov cuam tshuam ze-ntev.Yog li, OLT yuav tsum tau kho sai sai nws cov ntsiab lus "0" thiab "1" qib txiav txim siab.Txhawm rau daws qhov "kev cuam tshuam nyob ze", tau npaj lub tswv yim tswj fais fab, thiab OLT qhia rau ONU ntawm qib xa hluav taws xob los ntawm kev khiav hauj lwm thiab kev tswj xyuas (OAM) pob ntawv tom qab sib txawv.Vim tias cov txheej txheem no yuav ua rau tus nqi ONU nce ntxiv thiab qhov nyuaj ntawm cov txheej txheem txheej txheem lub cev, thiab txwv txoj kab kev sib kis mus rau ONU theem deb tshaj plaws ntawm OLT, nws tsis tau txais los ntawm pawg neeg ua haujlwm EFM.