Ua ntej, qhov teeb meem dab tsi yog PON siv los daws?
● Nrog qhov tshwm sim ntawm cov kev pabcuam siab-bandwidth xws li video ntawm kev thov, kev ua si hauv online thiab IPTV, cov neeg siv yuav tsum tau ceev nrooj ntawm kev siv bandwidth.Existing ADSL-raws li broadband access txoj kev nyuaj zuj zus kom tau raws li cov neeg siv yuav tsum tau rau siab bandwidth, ob- txoj kev kis tau tus mob, thiab kev ruaj ntseg.
● Vim muaj qhov sib kis tau ntev, muaj zog tiv thaiv kev cuam tshuam thiab muaj peev xwm loj, cov khoom siv kho qhov muag tau siv dav hauv cov pob txha caj qaum. Nyob rau hauv xyoo tas los no, nrog kev txo qis ntawm tus nqi ntawm cov khoom siv kho qhov muag, cov khoom siv kho qhov muag tau maj mam dhau los ua thawj qhov kev xaiv rau kev sib kis nruab nrab ntawm kev nkag mus rau hauv lub network.
● Passive Optical Network (PON) yog tus nqi qis hauv kev siv fiber ntau thiab tuaj yeem hloov kho tau yooj yim. Nws tau txais kev pom zoo los ntawm cov tswv lag luam hauv xov tooj thiab suav tias yog qhov kev daws teeb meem zoo tshaj plaws los daws qhov teeb meem " mais kawg".
Qhov thib ob, qhov muaj pes tsawg leeg ntawm PON
Lub PON muaj peb ntu: ib qho kev txiav tawm kho qhov muag (OLT), ib qho chaw kho qhov muag network (ONU), thiab passive optical splitter (POS).
PON yog asymmetric, point-to-multipoint (P2MP) qauv. Lub luag hauj lwm ua los ntawm covOLTthiab covONUtxawv. CovOLTyog sib npaug rau lub luag hauj lwm ntawm tus Xib Hwb, thiab covONUyog sib npaug rau lub luag hauj lwm ntawm tus qhev.
Peb, qhov zoo ntawm PON:
● Txuag
P2P - Tsis muaj fiber ntau optical; 2N optical transceiver
P2PCurb - 1 fiber ntau; 2N + 2 optical transceiver; yuav tsum tau siv fais fab hauv zos; txuag fiber ntau
P2MP (PON) - 1 fiber ntau; N + 1 optical transceiver; ib tug loj tus naj npawb ntawm optical fibers tau txais kev cawmdim; ntau ntawm optical transceivers
● Txhim khu kev qha
Lub teeb liab tsis dhau los ntawm cov khoom siv hluav taws xob nquag thaum lub sijhawm PON kis tau tus mob, txo qhov muaj peev xwm ntawm qhov tsis ua haujlwm;
Kev siv cov khoom siv passive ua kom yooj yim lub network hierarchy, thiab cov qauv sib txuas sib txuas yooj yim dua los tswj thiab tswj.
● Ntev nrug
PON kis tau tus mob nrug yog 10 mus rau 20km, uas ua tiav qhov kev txwv ntawm qhov kev ncua deb ntawm Ethernet thiab xDSL txoj kev nkag, thiab txhim kho qhov yooj yim ntawm tus neeg teb xov tooj qhov kawg chaw ua haujlwm xa mus.
● High bandwidth
Piv nrog xDSL, PON muaj ntau dua bandwidth thiab ua tau raws li qhov xav tau ntawm HDTV hauv online tshaj tawm cov kev pabcuam yav tom ntej.
● Yooj yim
PON networking qauv tsis txwv, thiab lub network ntawm tsob ntoo thiab lub hnub qub topology tuaj yeem ua tau yooj yim.
PON yog qhov tshwj xeeb tshaj yog haum rau lub sijhawm uas tus neeg siv nkag mus rau cov ntaub ntawv cov ntsiab lus tau tawg, thiab lub cev kho qhov muag fiber ntau tuaj yeem txaus siab rau txhua tus neeg siv nkag mus rau cov ntaub ntawv cov ntsiab lus.
Plaub, tus qauv tseem ceeb ntawm PON
● GPON – GigabitPON, ITUG.984 raws tu qauv qauv, txawj tej yam ntxiv thiab txuas ntxiv ntawm APON, siv ib tug ntau thav duab hom los muab kev txhawb rau ntau yam kev pab cuam. Qhov siab tshaj plaws yog 2.5Gbps. GPON muaj qhov zoo ntawm kev kub ceev thiab kev txhawb nqa rau ntau yam kev pabcuam, tab sis cov thev naus laus zis yog qhov nyuaj, tus nqi siab, thiab kev loj hlob ntawm cov khoom tsis siab.
● EPON—Ethernetover PON, IEEE802.3ah raws tu qauv qauv, uas xa cov ntawv Ethernet hom ntawv ntawm PON network thiab tuaj yeem txhawb 1.25Gbps symmetric tus nqi. EPON yog raws li Ethernet thev naus laus zis thiab cov txheej txheem yooj yim thiab ua haujlwm tau zoo. Piv nrog APON, GPON muaj qhov pom tseeb zoo ntawm tus nqi.
Thib tsib, Cov thev naus laus zis tseem ceeb ntawm EPON
● Channel multiplexing
EPON system txais WDM thev naus laus zis kom paub txog ib leeg-fiber bidirectional kis tau tus mob;
Tus nqi channel yog 1.25 Gbps sab sauv thiab qis.
● EPON downlink kis tau tus mob hom – tshaj tawm hom
● EPON uplink kis hom - TDMA hom
● Multipoint Control Protocol – MPCP
Tsis zoo li Ethernet P2P architecture, PON yog P2MP architecture. CovONUsib tw rau uplink channel cov peev txheej, thiab yuav tsum muaj kev txiav txim siab txog kev txiav txim siab kom tsis txhob muaj cov ntaub ntawv uplink sib tsoo thiab faib cov peev txheej channel kom zoo. 802.3ah raws tu qauv qhia txog kev tswj hwm raws tu qauv, Multi-point MAC Control Protocol (MPCP);
lMPCP feem ntau txhais lub Multi-point MAC Control sublayer kom txuas ntxiv thiab hloov MAC Control sublayer txhais los ntawm 802.3 raws tu qauv. Cov txheej txheem tswj hwm ntawm MPCP raws tu qauv muaj qhov tseem ceeb dua li MAClient cov ntaub ntawv.
● Kev them nyiaj ntau thiab ncua sij hawm
EPON uplink kis tau tus mob txais TDMA hom. CovOLTtxiav txim lub sij hawm rau lubONUxa cov ntaub ntawv. Txij li txhua tusONUyog txawv ntawm covOLT, yuav muaj qhov sib txawv qeeb. Yog tias tsis muaj kev cuam tshuam kev them nyiaj qeeb qeeb, cov ntaub ntawv uplink kis tau tus mob tseem yuav tshwm sim.
EPON sib txawv thiab ncua sij hawm them nyiaj yog cov thev naus laus zis tseem ceeb rau uplink channel multiplexing. Ø Nyob rau hauv cov txheej txheem DiscoveryProcessing, lubOLTxam tus nqi RTT (RoundTrip Time) ntawm txhua tusONUlos ntawm kev ntsuas cov ntawv sau npe tshiabONU.
CovOLTsiv RTT los kho lub sijhawm tso cai ntawm txhua tusONU.
CovOLTkuj tseem tuaj yeem pib sib txawv thaum nws tau txais MPCP PDU.
Kev suav RTT:
GATE ncej muaj qhov "timestamp" teb uas covONUsiv los hloov kho lub sijhawm sau npe hauv zos. CovOLTtuaj yeem xam RTT los ntawm qhov tau txais REPORT ncej los ua qhov kev sim nyiaj.
● Dynamic Bandwidth Allocation (DBA)
Kev sib piv ntawm cov sij hawm tas li thiab cov sij hawm dynamic:
