Ngophuhliso lothungelwano lonxibelelwano olubhekiselele kwibroadband kunye nokuhamba, inkqubo yonxibelelwano lwefiber optical fiber (ROF) idibanisa unxibelelwano lwefiber optical kunye nonxibelelwano olungenazingcingo, inika umdlalo opheleleyo kwiinzuzo zebroadband kunye nokuchasana nokuphazamiseka kwemigca yefiber optical, kunye nonxibelelwano olungenazingcingo. .Iimpawu ezifanelekileyo neziguquguqukayo ziyahlangabezana nemfuno yabantu yebroadband.Itekhnoloji yokuqala ye-ROF yayinikezelwe ikakhulu ekuboneleleni ngeenkonzo zothumelo lwe-wireless ezikwi-frequency ephezulu, ezinje nge-millimeter wave optical fiber transmission.Ngophuhliso kunye nokuvuthwa kweteknoloji yeROF, abantu baqala ukufunda i-hybrid wired and wireless transmission networks, oko kukuthi, iinkqubo ze-fiber optical fiber communication (ROF) ezibonelela ngeenkonzo zeengcingo kunye neengcingo ngaxeshanye.Ngophuhliso olukhawulezayo lonxibelelwano lukanomathotholo, ukunqongophala kwemithombo ye-spectrum kuye kwabonakala ngakumbi.Indlela yokuphucula ukusetyenziswa kwe-spectrum phantsi kwemeko yobuncwane obunqamlekileyo obungenazingcingo ukunciphisa ukuchasana phakathi kokubonelela kunye nemfuno yemithombo ye-spectrum ibe yingxaki ekufuneka isonjululwe kwintsimi yonxibelelwano.Irediyo yolwazi (i-CR) bubuchwephesha bokwabelana nge-spectrum obukrelekrele.Inokuphucula ngokufanelekileyo ukusetyenziswa kwemithombo ye-spectrum ngokusebenzisa "ukusetyenziswa okwesibini" kwe-spectrum egunyazisiweyo, kwaye ibe yindawo yophando kwinkalo yonxibelelwano.Kwinethiwekhi yendawo engenazingcingo ye-802.11 [1], i-802.16 yenethiwekhi yendawo yemetropolitan [2] kunye nenethiwekhi yonxibelelwano lwe-3G yeselula [3] baye baqala ukufunda ukusetyenziswa kobuchwephesha be-cognitive radio ukuphucula amandla enkqubo, kwaye baqala ukufunda ukusetyenziswa kwe Itekhnoloji ye-ROF ukuphumeza ukuhanjiswa okuxutyiweyo kwemiqondiso eyahlukeneyo yeshishini[4].Uthungelwano lwerediyo olusekwe kwi-fiber ye-fiber engenazingcingo ezithumela iisignali ezinocingo kunye nezingenazingcingo yindlela yophuhliso yothungelwano lwexesha elizayo.Inkqubo ye-ROF yosasazo oluxubileyo olusekwe kwitekhnoloji yolwazi lwerediyo ijongene nemingeni emininzi emitsha, efana noyilo lwezakhiwo zenethiwekhi, uyilo lweprotocol yomaleko, ukuveliswa kwemiqondiso enengcingo kunye neengcingo ezimodyuliweyo ezisekelwe kwiinkonzo ezininzi, ulawulo lwenethiwekhi, kunye nokuchongwa kwemiqondiso ehlengahlengisiweyo.
1 Itekhnoloji yerediyo yokuqonda
Irediyo yengqondo yindlela esebenzayo yokusombulula ukunqongophala kwe-spectrum kunye nokusetyenziswa kakubi kwe-spectrum.Irediyo yolwazi yinkqubo yonxibelelwano engenazingcingo ekrelekrele.Iyakuva ukusetyenziswa kwezinto ezisingqongileyo kwaye ilungelelanise eyayo iparamitha ngokuguquguqukayo ngokufunda ukufikelela kusetyenziso olusebenzayo.Izixhobo ze-Spectrum kunye nonxibelelwano oluthembekileyo.Ukusetyenziswa koonomathotholo bengqondo bubuchwephesha obuphambili ekuqondeni ubutyebi be-spectrum ukusuka kulwabiwo olusisigxina ukuya kulwabiwo oluguquguqukayo.Kwi-cognitive radio system, ukwenzela ukukhusela umsebenzisi ogunyazisiweyo (okanye abe ngumsebenzisi oyintloko) ekuphazamisekeni komsebenzisi wekhoboka (okanye umsebenzisi we-CR), umsebenzi we-spectrum sensing kukubona ukuba ngaba umsebenzisi ogunyazisiweyo ukhona.Abasebenzisi berediyo bengqondo banokusebenzisa okwethutyana ibhendi yefrikhwensi xa ibekwe esweni ukuba ibhendi yefrikhwensi esetyenziswa ngumsebenzisi ogunyazisiweyo ayisetyenziswa.Xa kuhlolwa ukuba ibhendi ye-frequency yomsebenzisi ogunyazisiweyo isetyenziswa, umsebenzisi we-CR ukhulula itshaneli kumsebenzisi ogunyazisiweyo, ngaloo ndlela eqinisekisa ukuba umsebenzisi we-CR akaphazamisi umsebenzisi ogunyazisiweyo.Ke ngoko, uthungelwano lonxibelelwano olungenazingcingo lunezi mpawu zilandelayo: (1) Umsebenzisi ophambili unokubaluleka ngokupheleleyo ukufikelela kumjelo.Ngakolunye uhlangothi, xa umsebenzisi ogunyazisiweyo engahlali kwitshaneli, umsebenzisi wesibini unethuba lokufikelela kumjelo ongasebenziyo;xa umsebenzisi oyintloko evela kwakhona, umsebenzisi wesibini kufuneka aphume kwijelo elisetyenziswayo ngexesha kwaye abuyisele ijelo kumsebenzisi oyintloko.Ngakolunye uhlangothi, xa umsebenzisi oyintloko ethatha ijelo, umsebenzisi wekhoboka unokufikelela kwijelo ngaphandle kokuchaphazela umgangatho wenkonzo yomsebenzisi oyintloko.(2) I-terminal yonxibelelwano yeCR inemisebenzi yokubona, ukulawula kunye nokulungelelanisa.Okokuqala, i-terminal ye-CR yonxibelelwano inokubona i-frequency spectrum kunye ne-channel environment kwindawo yokusebenza, kwaye inqume ukwabelana kunye nokwabiwa kwezibonelelo ze-spectrum ngokwemigaqo ethile ngokweziphumo zokufumanisa;ngakolunye uhlangothi, i-terminal ye-CR yonxibelelwano inamandla okulungelelanisa iiparitha zokusebenza kwi-intanethi, njengokutshintsha Iiparamitha zokuhambisa ezifana ne-frequency carrier kunye nendlela yokumodareyitha inokulungelelanisa utshintsho kwimo engqongileyo.Kuthungelwano lonxibelelwano olungenazingcingo, ukubonwa kwe-spectrum yeyona teknoloji iphambili.I-algorithms ye-spectrum esetyenziswa ngokuqhelekileyo ibandakanya ukuchongwa kwamandla, ukuchongwa kokucoca okuhambelanayo, kunye neendlela zokufumanisa iimpawu ze-cyclostationary.Ezi ndlela zineengenelo kunye nezingeloncedo zazo.Ukusebenza kwezi algorithms kuxhomekeke kulwazi lwangaphambili olufunyenweyo.I-algorithms esele ikho ye-spectrum sensing zezi: isihluzo esihambelanayo, isikhangeli samandla kunye neendlela zokubona iimpawu.Isihluzi esihambelanayo sinokusetyenziswa kuphela xa umqondiso ophambili usaziwa.Umtshini wamandla ungasetyenziswa kwimeko apho umqondiso oyintloko ungaziwa, kodwa ukusebenza kwayo kuyancipha xa kusetyenziswa ixesha elifutshane lokuqonda.Kuba umbono ophambili wesixhobo sokujonga kukusebenzisa i-cyclostationarity yesiginali ukubona ngomsebenzi wokunxibelelanisa okubonakalayo.Ingxolo luphawu olumileyo olubanzi kwaye alunalunxulumano, ngelixa isiginali emodulisiweyo inxibelelene kunye ne-cyclostationary.Ngoko ke, umsebenzi wokulungelelaniswa kwe-spectral unokwahlula amandla omsindo kunye namandla omqondiso owenziweyo.Kwindawo enengxolo engaqinisekanga, ukusebenza kwesixhobo sokubona izinto kubhetele kunomtshina wamandla.Ukusebenza kwesikhangeli sesici phantsi komlinganiselo ophantsi wesignali ukuya kwingxolo ulinganiselwe, unobunzima obuphezulu bokubala, kwaye ufuna ixesha elide lokujongwa.Oku kunciphisa i-throughput yedatha ye-CR system.Ngophuhliso lwetekhnoloji yonxibelelwano olungenazingcingo, izibonelelo ze-spectrum ziya zisiba shushu ngakumbi.Ngenxa yokuba itekhnoloji yeCR inokuphelisa le ngxaki, itekhnoloji yeCR inikwe ingqwalasela kuthungelwano lonxibelelwano olungenazingcingo, kwaye imigangatho emininzi yonxibelelwano engenazingcingo iye yazisa itekhnoloji yerediyo yokuqonda.Ezinje nge-IEEE 802.11, IEEE 802.22 kunye ne-IEEE 802.16h.Kwisivumelwano se-802.16h, kukho umxholo obalulekileyo wokukhetha i-spectrum eguqukayo ukuququzelela ukusetyenziswa kwe-WiMAX yerediyo kunye neebhendi zefrikhwensi zikamabonwakude, kwaye isiseko sayo sithekhnoloji yokubona i-spectrum.Kumgangatho wamazwe ngamazwe we-IEEE 802.11h wothungelwano lwengingqi olungenazingcingo, iikhonsepthi ezimbini ezibalulekileyo ziye zaziswa: ukhetho lwe-dynamic spectrum (DFS) kunye nokulawula amandla okuhambisa (TPC), kunye nerediyo yokuqonda isetyenziswe kuthungelwano lwengingqi olungenacingo.Kumgangatho we-802.11y, iteknoloji ye-orthogonal frequency division multiplexing (OFDM) isetyenziselwa ukubonelela ngeendlela ezahlukeneyo zokukhetha i-bandwidth, ezinokufikelela ngokukhawuleza ukutshintshwa kwe-bandwidth.Iinkqubo ze-WLAN (inethiwekhi yendawo engenazingcingo) inokuthatha inzuzo yeempawu ze-OFDM ukuphepha ukuphepha ngokuhlengahlengisa i-bandwidth kunye nokuhambisa iiparamitha zamandla.Ukuphazamisa abanye abasebenzisi abasebenza kule bhendi yefrikhwensi.Ngenxa yokuba inkqubo ye-fiber optical fiber ine-advantes of wide optical fiber communication bandwidth kunye neempawu eziguquguqukayo zonxibelelwano lwamacingo, isetyenziswe ngokubanzi.Kwiminyaka yakutshanje, ukuhanjiswa kwee-radio frequency cognitive WLAN signals kwifiber optical kutsale umdla.Umbhali woncwadi [5-6] ucebise ukuba inkqubo ye-ROF Imiqondiso yerediyo yeCognitive ihanjiswa phantsi kolwakhiwo, kwaye iimvavanyo zokulinganisa zibonisa ukuba ukusebenza kwenethiwekhi kuye kwaphuculwa.
I-2 ye-ROF-based hybrid optical fiber transmission system ye-architecture
Ukuze kuhlangatyezwane neemfuno zeenkonzo zemultimedia zokusasazwa kwevidiyo, i-fiber-to-the-home (FFTH) iya kuba yeyona teknoloji yokufikelela kwi-broadband, kunye ne-passive optical network (PON) ibe yingqwalasela xa ifika. ngaphandle.Kuba izixhobo ezisetyenziswa kuthungelwano lwe-PON zizixhobo ezingenzi nto, azifuni mbane, zinokukhuseleka kwimpembelelo yokuphazamiseka kwe-electromagnetic yangaphandle kunye nombane, zinokufezekisa ukuhanjiswa kweenkonzo elubala, kwaye zibe nokuthembeka okuphezulu kwenkqubo.Uthungelwano lwe-PON lubandakanya ubukhulu becala ulwahlulo lwexesha lothungelwano lwe-multiplexing passive optical network (TDM-PON) kunye ne-wavelength division multiplexing networks optical passive (WDM-PON).Xa kuthelekiswa ne-TDM-PON, i-WDM-PON ineempawu ze-bandwidth ezikhethekileyo zomsebenzisi kunye nokhuseleko oluphezulu, ibe yinethiwekhi yokufikelela kwi-optical kwixesha elizayo.Umzobo 1 ubonisa umzobo webhloko wenkqubo ye-WDM-PON.