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, cwbONUtuaj yeem xa cov ntaub ntawv tsis pub dhau lub sijhawm qhov rai. 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.ONUsthiabOLTs.
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 covOLTyog muab los ntawm ntauONUcov neeg siv. 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
Yuav kom txo tau tus nqi ntawmONU, cov technologies tseem ceeb ntawm covEPONlub cev txheej yog concentrated nyob rau hauvOLT, suav nrog: ceev synchronization ntawm tawg teeb liab, network synchronization, tswj fais fab ntawm optical transceiver modules, thiab kev txais tos txais.
Txij li thaum lub teeb liab tau txais los ntawm lubOLTyog lub teeb liab tawg ntawm txhua tusONU, covOLTyuav tsum muaj peev xwm ua tiav theem synchronization hauv lub sijhawm luv luv, thiab tom qab ntawd tau txais cov ntaub ntawv. Tsis tas li ntawd, vim hais tias lub uplink channel txais yuav 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 qhov sib txawv ntawm txhua qhovONUlos ntawmOLT, rau lub txais module ntawm lubOLT, 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 ntawd, lubOLTyuav tsum tau kho sai sai nws cov ntsiab lus "0" thiab "1" qib txiav txim siab. Txhawm rau kom daws tau qhov "kev cuam tshuam deb", tau npaj lub tswv yim tswj fais fab, thiabOLTqhia rauONUntawm kev xa hluav taws xob theem 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 rauONUtheem deb tshaj plaws ntawm lubOLT, nws tsis tau txais los ntawm EFM pawg ua haujlwm.