1. OFDM

 

Theknoloji ea OFDM e arola mocha o fanoeng ho li-channel tse ngata tsa orthogonal sebakeng sa maqhubu.Subcarrier e le 'ngoe e sebelisetsoa modulation ho subchannel e' ngoe le e 'ngoe,' me e 'ngoe le e 'ngoe e tsamaisana le eona e fetisoa ka ho tšoana.Ka tsela ena, le hoja mocha ka kakaretso o sa bataletse ebile o khetha khafetsa.Empa subchannel ka 'ngoe e batla e bataletse.Phetisetso ea Narrowband e etsoa mocha o mong le o mong o monyenyane, 'me bandwidth ea pontšo e nyenyane ho feta bandwidth e lumellanang ea mocha.Ka hona, ho kena-kenana pakeng tsa maqhubu a maqhubu a pontšo ho ka felisoa haholo.

Kaha bajari ba kanale e 'ngoe le e' ngoe e nyane ba na le orthogonal ho e mong tsamaisong ea OFDM.Maqhubu a tsona a kopana.Sena ha se fokotse feela ho kena-kenana pakeng tsa li-sub-carriers, empa hape se ntlafatsa tšebeliso ea spectrum.

 

2. COFDM

 

COFDMis Coded Orthogonal Frequency Division Multiplexing, e bolelang

pele ho feto-fetoha ha OFDM, phallo ea khoutu ea dijithale e kentsoe.

Coded ee e etsa'ng?Ke likhoutu tsa mocha (ho fana ka likhoutu tsa mohloli ke ho rarolla bothata ba ho sebetsa hantle, 'me likhoutu tsa mocha ke ho netefatsa ho ts'epahala ha phetisetso).

 

Mokhoa o khethehileng ke:

 

2.1.Tokiso ea Phoso ea Pele(FEC)

 

Mohlala, li-bits tse 100 tsa data li hloka ho feto-fetohabakeng safetisang.E fetole pele ho li-bits tse 200,.Ha lets'oao le amoheloa, leha ho na le bothata ka phetiso ea li-bits tse 100, data e nepahetseng e ntse e ka theoleloa.Ka bokhutšoanyane, ke ho eketsa redundancy pele ho modulation ho ntlafatsa ho tšepahala ha phetiso.Sena se bitsoa Phoso ea ka hare ea Phoso (FEC) mekhoeng ea COFDM.Mme ket ke parameter ea bohlokoa ea tsamaiso ea COFDM.

 

 

2.2.Sekhahla sa Molebeli

 

Fkapa morero oa solvngbongata-bothata ba tselake horelets'oao le fetisitsoeng le fihla pheletsong ea ho amohela ka litsela tse ngata tsa phetiso. Akarohano ea molebeli e kenngoa pakeng tsa likotoana tsa data tse fetisoang.