Ngaphambi kokuqonda ubuchwepheshe be-PAM4, buyini ubuchwepheshe bokushintshashintsha? Ubuchwepheshe bokushintshashintsha buyindlela yokuguqula izimpawu ze-baseband (izimpawu zikagesi ezingavuthiwe) zibe izimpawu zokudlulisa. Ukuze kuqinisekiswe ukusebenza kahle kokuxhumana nokunqoba izinkinga ekudlulisweni kwezimpawu zebanga elide, kubalulekile ukudlulisa i-spectrum yesignali esiteshini esinomvamisa ophezulu ngokusebenzisa ukuguqulwa kokudlulisa.
I-PAM4 iyindlela yokuguqula i-pulse amplitude modulation (PAM) ye-fourth order.
Isignali ye-PAM ubuchwepheshe bokudlulisa isignali obudumile ngemva kwe-NRZ (Non Return to Zero).
Isignali ye-NRZ isebenzisa amazinga amabili esignali, aphezulu naphansi, ukumela u-1 no-0 wesignali ye-logic yedijithali, futhi ingadlulisela ulwazi lwe-logic oluyi-1 bit ngomjikelezo wewashi.
Isignali ye-PAM4 isebenzisa amazinga ama-signal ahlukene angu-4 okudlulisa isignali, futhi umjikelezo ngamunye wewashi ungadlulisela ama-bits amabili olwazi lwe-logic, okungukuthi u-00, u-01, u-10, no-11.
Ngakho-ke, ngaphansi kwezimo ezifanayo zesilinganiso se-baud, izinga le-bit lesiginali ye-PAM4 liphindwe kabili kunelesignali ye-NRZ, okuphinda kabili ukusebenza kahle kokudlulisa futhi kunciphisa izindleko ngempumelelo.
Ubuchwepheshe be-PAM4 busetshenziswe kabanzi emkhakheni wokuxhumana kwesignali ngesivinini esikhulu. Njengamanje, kune-module ye-transceiver ye-optical engu-400G esekelwe kubuchwepheshe bokuguqulwa kwe-PAM4 yesikhungo sedatha kanye ne-module ye-transceiver ye-optical engu-50G esekelwe kubuchwepheshe bokuguqulwa kwe-PAM4 yenethiwekhi yokuxhumeka ye-5G.
Inqubo yokusebenzisa i-module ye-transceiver ye-optical ye-400G DML esekelwe ekuguqulweni kwe-PAM4 imi kanje: lapho kuthunyelwa izimpawu zeyunithi, iziteshi ezingu-16 ezitholiwe zezibonakaliso zikagesi ze-25G NRZ zifakwa kusuka kuyunithi yesixhumi esibonakalayo sikagesi, zicutshungulwe kusengaphambili yiprosesa ye-DSP, zilungiswe yi-PAM4, bese zikhishwa iziteshi ezingu-8 zezibonakaliso zikagesi ze-25G PAM4, ezilayishwa ku-chip yomshayeli. Izimpawu zikagesi zesivinini esiphezulu ziguqulwa zibe iziteshi ezingu-8 zezibonakaliso ze-optical zesivinini esiphezulu ze-50Gbps ngeziteshi ezingu-8 zama-laser, zihlanganiswe yi-multiplexer yokuhlukanisa ubude be-wavelength, futhi zenziwe zibe isiteshi esingu-1 sokukhishwa kwesignali ye-optical yesivinini esiphezulu ye-400G. Lapho kwamukelwa izimpawu zeyunithi, isignali ye-optical yesiteshi esingu-1 etholiwe yesiteshi esingu-400G ifakwa ngeyunithi yesixhumi esibonakalayo esibonakalayo, iguqulwe ibe isignali ye-optical yesivinini esiphezulu yesiteshi esingu-8 ye-50Gbps nge-demultiplexer, itholwe yisamukeli se-optical, futhi iguqulwe ibe isignali kagesi. Ngemva kokubuyiselwa kwewashi, ukukhulisa, ukulinganisa, kanye nokususwa kwe-PAM4 yi-chip yokucubungula i-DSP, isignali kagesi iguqulwa ibe iziteshi ezingu-16 zesignali kagesi engu-25G NRZ.
Sebenzisa ubuchwepheshe bokuguqulwa kwe-PAM4 kumamojula we-optical angu-400Gb/s. Imojula ye-optical engu-400Gb/s esekelwe ekuguqulweni kwe-PAM4 inganciphisa inani lama-laser adingekayo ekugcineni kokudlulisa futhi inciphise ngokufanayo inani lama-receiver adingekayo ekugcineni kokwamukela ngenxa yokusebenzisa amasu okuguqulwa aphezulu uma kuqhathaniswa ne-NRZ. Ukuguqulwa kwe-PAM4 kunciphisa inani lezingxenye ze-optical kumojula we-optical, okungaletha izinzuzo ezifana nezindleko zokuhlanganisa eziphansi, ukusetshenziswa kwamandla okuncishisiwe, kanye nosayizi wokupakisha omncane.
Kunesidingo samamojula optical angu-50Gbit/s kumanethiwekhi okudlulisa kanye nokubuyela emuva kwe-5G, futhi isisombululo esisekelwe kumadivayisi optical angu-25G futhi esingezwe yifomethi ye-PAM4 pulse amplitude modulation siyasetshenziswa ukuze kufezwe izidingo ze-bandwidth ezishibhile neziphezulu.
Uma uchaza izimpawu ze-PAM-4, kubalulekile ukunaka umehluko phakathi kwesilinganiso se-baud kanye nesilinganiso se-bit. Kumasignali endabuko e-NRZ, njengoba uphawu olulodwa ludlulisela idatha encane, izinga le-bit kanye nezinga le-baud kuyafana. Isibonelo, ku-100G Ethernet, kusetshenziswa izimpawu ezine ze-25.78125GBaud zokudlulisa, izinga le-bit kusignali ngayinye nalo lingu-25.78125Gbps, kanti izimpawu ezine zifinyelela ukudluliselwa kwesignali engu-100Gbps; Kumasignali e-PAM-4, njengoba uphawu olulodwa ludlulisela idatha engama-bits ama-2, izinga le-bit elingadluliselwa liphindwe kabili kunezinga le-baud. Isibonelo, kusetshenziswa iziteshi ezine zezibonakaliso ze-26.5625GBaud zokudlulisa ku-200G Ethernet, izinga le-bit kusiteshi ngasinye lingu-53.125Gbps, kanti iziteshi ezine zezibonakaliso zingafinyelela ukudluliselwa kwesignali engu-200Gbps. Ku-400G Ethernet, kungafinyelelwa ngeziteshi ezingu-8 zezibonakaliso ze-26.5625GBaud.
Isikhathi sokuthunyelwe: Jan-02-2025