OFDM tau tshaj tawm hauv IEEE 802.11a.Raws li cov qauv kev hloov kho no, peb yuav tsum paub tias OFDM yog dab tsi kom nkag siab txog cov txheej txheem sib txawv.
OFDM yog dab tsi?
OFDM yog ib qho tshwj xeeb multi-carrier modulation technology.Cov thev naus laus zis no tsom rau kev faib cov channel rau ntau qhov chaw orthogonal sub-channels, thiab tom qab ntawd hloov cov ntaub ntawv ceev ceev rau hauv cov ntaub ntawv qis qis rau kev sib kis, uas tau hloov kho thiab xa mus rau txhua qhov sub-channel.Txhua lub subcarrier yog orthogonal rau lwm tus, thiab cov zaus raws tom qab kis spectrum modulation tuaj yeem sib tshooj, txo qhov cuam tshuam ntawm subcarriers thiab txhim kho kev siv spectrum.
Yuav ua li cas to taub orthogonal tsis cuam tshuam: thaum ib tug subcarrier mus txog lub ncov, lub amplitude ntawm lwm subcarrier yog 0. Qhov ntawd yog, ob lub subcarriers yog orthogonal yam tsis muaj kev cuam tshuam.Raws li pom nyob rau hauv daim duab hauv qab no, thaum lub xiav tuaj txog amplitude yog siab tshaj, lwm subcarrier yog 0.
Tsis tas li ntawd, OFDM tuaj yeem siv cov subcarriers uas sib tshooj vim tias cov subcarriers tau txhais nyob rau hauv ib txoj kev uas ua rau lawv yooj yim qhia sib nrug.
Lub teeb liab muab faib ua peb subcarriers, los ntawm sab laug mus rau sab xis.Txhua subcarrier ncov yog siv rau cov ntaub ntawv coding, raws li qhia nyob rau hauv lub liab dot nyob rau hauv daim duab, uas sib haum mus rau 0 scale kab hauv qab no.Ib tug mus txog lub ncov, thiab tus so nce mus txog 0. Cov subcarriers no txhob txwm tsim kom muaj kev sib raug zoo orthogonal rau ib leeg.Lub ncov ntawm txhua tus subcarrier Lub sijhawm no, qhov amplitude ntawm ob lub subcarrier yog 0.
5GHz OFDM channel:
5GHz channel muaj 52 subcarriers, thiab txhua tus subcarrier muaj 312.5 kHz.Muaj 48 channels rau kev xa cov ntaub ntawv, thiab 4 channel yog siv rau theem siv.
OFDM subchannel modulation tshuab siv QAM (QAM yog cov ntawv luv ntawm quadrature amplitude modulation, uas yog txhais ua "quadrature amplitude modulation" hauv Suav).QAM siv lub amplitude thiab theem ntawm cov cab kuj nthwv dej los xa cov ntaub ntawv.
Cov saum toj no yog cov kev paub piav qhia ntawm OFDM-802.11 raws tu qauv coj los rau koj los ntawmShenzhen HDV Phoelectron Technology Co., Ltd.vam tias tsab xov xwm no tuaj yeem pab koj nce koj txoj kev paub.Dhau li ntawm tsab xov xwm no yog tias koj tab tom nrhiav rau lub tuam txhab kev sib txuas lus zoo fiber ntau cov khoom lag luam koj tuaj yeem xav txogtxog peb.
Cov khoom sib txuas lus tsim los ntawm lub tuam txhab npog:
Module: optical fiber modules, Ethernet modules, Optical fiber ntau transceiver modules, optical fiber nkag modules, SSFP optical modules, thiabSFP optical fibers, lwm.
ONU qeb: EPON UA, AC ONU, Optical fiber ntau ONU, CATV UA, GPON UA, XOV TOOJ, lwm.
OLT chav kawm: OLT hloov, GPON OLT, PEB OLT, kev sib txuas lus OLT, thiab lwm yam.
Cov khoom saum toj no tuaj yeem txhawb nqa cov xwm txheej sib txawv.Rau cov khoom lag luam saum toj no, ib pab neeg ua haujlwm R & D muaj zog tau ua ke los muab kev txhawb nqa rau cov neeg siv khoom, thiab pab pawg ua lag luam xav tau zoo tuaj yeem muab cov kev pabcuam zoo rau cov neeg siv khoom thaum ntxov.kev sab lajthiab tom qab ntawd ua haujlwm.