Choyamba, ndi vuto lanji lomwe PON amagwiritsidwa ntchito kuthetsa?
● Ndi kutuluka kwa mautumiki apamwamba a bandwidth monga mavidiyo omwe akufunidwa, masewera a pa intaneti ndi IPTV, ogwiritsa ntchito akufunikira mwamsanga kuonjezera bandwidth. njira kufala mphamvu, ndi chitetezo.
● Chifukwa cha mtunda wautali wotumizira, mphamvu zotsutsana ndi zosokoneza komanso mphamvu zazikulu, kuwala kwa kuwala kwagwiritsidwa ntchito kwambiri pamsana wam'mbuyo. M'zaka zaposachedwa, ndi kuchepa kwa mtengo wa chipangizo cha optical, kuwala kwa fiber pang'onopang'ono kwakhala chisankho choyamba pa njira yotumizira mauthenga.
● Passive Optical Network (PON) ndi yotsika mtengo mu njira ya fiber access mode ndipo ikhoza kukwezedwa bwino. Imakondedwa kwambiri ndi ogwira ntchito pa telecom ndipo imatengedwa kuti ndi njira yabwino yothetsera vuto la "mailesi omaliza".
Chachiwiri, kapangidwe ka PON
PON ili ndi magawo atatu: kutha kwa mzere wa kuwala (OLT), mawonekedwe a netiweki (ONU), ndi passive optical splitter (POS).
PON ndi mawonekedwe asymmetric, point-to-multipoint (P2MP). Maudindo omwe amasewera ndiOLTndiONUndi zosiyana. TheOLTndizofanana ndi udindo wa Mbuye, ndiONUzikufanana ndi udindo wa Kapolo.
Chachitatu, ubwino wa PON:
● Kusunga
P2P - Palibe ulusi wa kuwala; 2N kuwala kwa transceiver
P2PCurb - 1 CHIKWANGWANI; 2N+2 transceiver kuwala; amafuna magetsi am'deralo; amapulumutsa ulusi wambiri
P2MP (PON) - 1 CHIKWANGWANI; Transceiver ya N+1; ulusi wambiri wa kuwala wopulumutsidwa; kuchuluka kwa ma transceivers owoneka
● Wodalirika
Chizindikiro sichidutsa pa chipangizo chamagetsi chogwira ntchito panthawi ya kufalitsa kwa PON, kuchepetsa kwambiri zomwe zingatheke;
Kugwiritsa ntchito zida zopanda pake kumathandizira kuwongolera maukonde, ndipo mawonekedwe a netiweki a flattened ndi osavuta kukonza ndikuwongolera.
● Mtunda wautali
Mtunda wotumizira wa PON ndi 10 mpaka 20km, womwe umagonjetsa malire a mtunda wapakati pa Ethernet ndi xDSL njira zopezera, ndipo zimakulitsa kwambiri kusinthasintha kwa kutumizidwa kwa ofesi yomaliza.
● Kuthamanga kwambiri
Poyerekeza ndi xDSL, PON ili ndi bandwidth yapamwamba ndipo imakwaniritsa zosowa zamtsogolo zapaintaneti za HDTV.
● Wololera
Mtundu wapaintaneti wa PON ulibe malire, ndipo maukonde amitengo ndi nyenyezi amatha kumangidwa mosinthika.
PON ndiyoyenera makamaka nthawi zomwe zidziwitso za ogwiritsa ntchito zimabalalika, ndipo thunthu la optical fiber limatha kukhutiritsa mwayi wa ogwiritsa ntchito onse kuti apeze zidziwitso.
Chachinayi, muyezo waukulu wa PON
● GPON - GigabitPON, ITUG.984 protocol standard, kukweza ndi kukulitsa APON, pogwiritsa ntchito mawonekedwe amtundu wamba kuti apereke chithandizo cha mautumiki osiyanasiyana. Mlingo wapamwamba kwambiri ndi 2.5Gbps. GPON ili ndi ubwino pa liwiro lalitali ndi chithandizo cha mautumiki angapo, koma teknoloji ndi yovuta, mtengo wake ndi wokwera, ndipo kukhwima kwa mankhwala sikuli kwakukulu.
● EPON——Ethernetover PON, IEEE802.3ah protocol standard, yomwe imatumiza mapaketi amtundu wa Efaneti pa netiweki ya PON ndipo imatha kuthandizira 1.25Gbps symmetric rate. EPON imachokera paukadaulo wa Efaneti ndipo protocol ndiyosavuta komanso yothandiza. Poyerekeza ndi APON, GPON ili ndi zabwino zodziwikiratu pamitengo.
Chachisanu,Makiyi aukadaulo a EPON
● Kuchulukitsa njira
Dongosolo la EPON limagwiritsa ntchito ukadaulo wa WDM kuti uzindikire kufalikira kwamtundu umodzi wa fiber bidirectional;
Mtengo wa tchanelo ndi 1.25 Gbps kumtunda ndi kutsika.
● EPON downlink transmission mode - njira yowulutsira
● EPON uplink transmission mode – TDMA mode
● Multipoint Control Protocol – MPCP
Mosiyana ndi kamangidwe ka Ethernet P2P, PON ndi kamangidwe ka P2MP. TheONUimapikisana ndi zida za uplink, ndipo njira yolumikizirana ndiyofunikira kuti mupewe kugundana kwa data ya uplink ndikugawa moyenera zothandizira. Protocol ya 802.3ah imatanthawuza njira yolamulira yofananira, Multi-point MAC Control Protocol (MPCP);
lMPCP makamaka imatanthawuza Multi-point MAC Control sublayer kuti iwonjezere ndikusintha MAC Control sublayer yofotokozedwa ndi 802.3 protocol. Dongosolo lowongolera la protocol ya MPCP limakhala lofunikira kwambiri kuposa mawonekedwe a data a MACClient.
● Kubweza ndi kuchedwa
Kutumiza kwa EPON uplink kumatengera mawonekedwe a TDMA. TheOLTamasankha nthawi yaONUkutumiza deta. Popeza aliyenseONUndi yosiyana ndiOLT, padzakhala kusiyana kochedwa. Ngati palibe njira yolipirira yochedwa yochedwetsa, mkangano wotumizira ma data a uplink udzachitikabe.
Kulipira kwa EPON ndi kuchedwetsa kubweza ndiye matekinoloje ofunikira pakuchulukitsa kwa njira za uplink. Ø Munjira ya DiscoveryProcessing, theOLTimawerengera mtengo wa RTT (RoundTrip Time) wa chilichonseONUpoyesa olembetsa kumeneONU.
TheOLTamagwiritsa RTT kusintha nthawi yovomerezeka ya aliyenseONU.
TheOLTimathanso kuyambitsa kuyambira pomwe ilandila MPCP PDU.
Kuwerengera kwa RTT:
Chimango cha GATE chili ndi gawo la "timestamp" lomweONUamagwiritsa ntchito kutsitsimutsa kaundula wa nthawi yakomweko. TheOLTakhoza kuwerengera RTT kupyolera mu REPORT yolandirira chimango kuti apereke malipiro oyesera.
● Dynamic Bandwidth Allocation (DBA)
Kuyerekeza kwa nthawi yokhazikika komanso mipata yanthawi yosinthika:
