WCDMA vs LTE
WCDMA (Wideband Code Division Multiple Access) thiab LTE (Long Term Evolution) yog cov thev naus laus zis sib txuas lus hauv xov tooj uas poob rau hauv 3rd Generation Partnership Project (3GPP) tso tawm. LTE cov qauv yog ib feem ntawm qhov tseeb 3GPP tshaj tawm, uas yog suav tias yog 4th Generation (4G), thiab WCDMA yog cov thev naus laus zis qub uas tau teev tseg raws li 3rd Generation (3G) technologies. LTE tso tawm muab tus naj npawb ntawm cov kev hloov hauv vaj tse thaum piv nrog WCDMA network.
WCDMA
WCDMA yog tus qauv European uas ua tiav 3G specifications luam tawm los ntawm IMT-2000 (International Mobile Telecommunication). WCDMA tau tsim los ua kom tiav cov ntaub ntawv tus nqi mus txog 2Mbps hauv qhov chaw nyob ruaj khov, thaum 384kbps hauv ib puag ncig txawb. WCDMA siv pseudo random teeb liab los hloov cov teeb liab thawj zaug rau hauv ib lub bandwidth siab dua, qhov twg thawj lub teeb liab tso rau hauv lub suab nrov. Txhua tus neeg siv yuav tau txais ib qho tshwj xeeb pseudo random code los cais cov thawj lub teeb liab los ntawm huab cua interface. WCDMA siv Quadrature Phase Shift Keying (QPSK) raws li kev hloov pauv, thaum siv Frequency Division Duplexing (FDD) raws li txoj kev duplexing. WCDMA architecture muaj cais Circuit Switched (CS) core network thiab Packet Switched (PS) core network. CS core muaj Media Gateway (MGw) thiab MSC-S (Mobile Switching Center-Server), thaum PS core muaj xws li Kev Pabcuam GPRS Support Node (SGSN) thiab Gateway GPRS Support Node (GGSN). Xov tooj cua nkag network ntawm WCDMA muaj xws li Xov tooj cua Network Controller (RNC) thiab Node-B. Nyob rau hauv no, RNC koom nrog MGw thiab SGSN rau CS cov ntaub ntawv thiab rau PS cov ntaub ntawv feem.
LTE
LTE tau qhia hauv 3GPP tso tawm 8 thaum Lub Kaum Ob Hlis 2008. LTE siv Orthogonal Frequency Division Multiplexing (OFDM) rau downlink, thiab Ib Lub Cev Muaj Peev Xwm Ntau Yam Kev Nkag Nkag (SC-FDMA) rau kev nkag mus. LTE Qeb 3 cov neeg siv khoom siv yuav tsum txhawb nqa txog 100Mbps hauv downlink, thiab 50Mbps hauv uplink. LTE muaj ntau qhov chaw tiaj tus nrog eNode-B, System Architecture Evolution Gateway (SAE-GW), thiab Mobile Management Entity (MME). eNode-B txuas nrog MME thiab nrog SAE-GW rau kev tswj lub dav hlau cov ntaub ntawv hloov tsheb (Signalling), thiab rau cov neeg siv dav hlau cov ntaub ntawv hloov tsheb (cov ntaub ntawv neeg siv) feem. LTE muaj peev xwm ua tau zoo spectral efficiency nrog OFDM, thaum muab robustness rau multipath fading. LTE txhawb nqa cov kev pabcuam xws li VoIP, Multicasting, thiab tshaj tawm tshaj tawm tau zoo dua li 3GPP cov lus qhia dhau los.
Qhov txawv ntawm WCDMA thiab LTE yog dab tsi?
WCDMA tau teev nyob rau hauv 3GPP tso tawm 99 thiab 4 ntawm qhov tshwj xeeb, thaum LTE tau teev tseg hauv 3GPP tso tawm 8 thiab 9. Tsis zoo li WCDMA, LTE txhawb nqa qhov sib txawv ntawm bandwidth los ntawm 1.25MHz txog 20MHz. Thaum cov ntaub ntawv tus nqi sib piv, LTE muab loj downlink thiab uplink speeds tshaj WCDMA. Tsis tas li ntawd, qhov ua tau zoo ntawm spectral yog ntau dua hauv LTE dua li ntawm WCDMA. LTE muab ntau yooj yim thiab tiaj tus network architecture dua li ntawm WCDMA. CS core network ib feem ntawm WCDMA, uas suav nrog MGW thiab MSC Server tau hloov tag nrho los ntawm PS core hauv LTE siv SAE-GW thiab MME. Tsis tas li ntawd, PS core nodes ntawm WCDMA uas muaj GGSN thiab SGSN raug hloov los ntawm tib SAE-GW thiab MME feem. RNC thiab Node-B nodes nyob rau hauv WCDMA architecture yog kiag li hloov los ntawm ntau tiaj tiaj architecture nrog tsuas yog eNode-B hauv LTE. Tshiab interface ntawm eNode-B's tau qhia hauv LTE, uas tsis muaj nyob hauv WCDMA. LTE tau ua kom zoo dua qub rau cov kev pabcuam IP pob ntawv; Tsis muaj qhov hloov pauv hauv Circuit Court nrog WCDMA. LTE muab kev yooj yim dua li ntawm WCDMA thaum los txog rau lub network topology thiab scalability. Feem ntau, WCDMA raug suav tias yog 3G thev naus laus zis thaum LTE suav tias yog 4G thev naus laus zis.
LTE muab cov ntaub ntawv ntau dua li WCDMA los ntawm kev ua tiav cov txiaj ntsig zoo dua. Tsis tas li ntawd, LTE thev naus laus zis muab ntau cov vaj tsev tiaj tus uas yog tsom rau IP pob ntawv raws li kev pabcuam tshaj li ntawm WCDMA. LTE topology yog qhov hloov pauv tau ntau dua thiab tuaj yeem hloov tau ntau dua li ntawm WCDMA vim qhov tiaj tus ntawm architecture.
