Kedu ihe bụ PON? Nkà na ụzụ ịnweta brọdband na-arị elu, a kara aka na ọ ga-abụ ogige agha ebe anwụrụ ọkụ na-agaghị apụ apụ. Ka ọ dị ugbu a, ihe eji arụ ọrụ ụlọ ka bụ teknụzụ ADSL, mana ọtụtụ ndị na-emepụta akụrụngwa na ndị na-arụ ọrụ etinyela uche ha na teknụzụ ịnweta netwọkụ anya.
Ọnụ ahịa ọla kọpa na-aga n'ihu na-arị elu, ọnụ ahịa eriri na-aga n'ihu na-adaba, na mmụba na-arịwanye elu maka IPTV na ọrụ egwuregwu vidiyo na-eme ka ọganihu nke FTTH. Atụmanya mara mma nke iji dochie eriri ọla kọpa na eriri coaxial wired site na eriri anya, telifon, USB TV, na brọdband data egwuregwu ugboro atọ na-apụta ìhè.
Foto 1: PON topology
PON (Passive Optical Network) netwọk anya na-agafe agafe bụ teknụzụ bụ isi iji ghọta eriri FTTH n'ụlọ, na-enye ohere ịnweta fiber-na-multipoint, dị ka egosiri na Figure 1, ọ bụOLT(oghere ahịrị ngwa anya) na akụkụ onye ọrụ nke akụkụ ụlọ ọrụ. NkeONU(Optical Network Unit) na ODN (Optical Distribution Network) mejupụtara.N'ozuzu, the downlink adopts the TDM broadcast mode and the uplink adopts the TDMA (Time Division Multiple Access) mode to form a point-to-multipoint tree topology.The Ihe kacha pụta ìhè nke PON dị ka teknụzụ ịnweta anya bụ "na-agafe agafe". ODN enweghị ngwaọrụ eletrọnịkị ọ bụla na-arụ ọrụ yana ọkụ eletrik. Ihe niile mejupụtara ha bụ ihe ndị na-agafe agafe dị ka ndị nkesa, nke nwere obere njikwa na ụgwọ ọrụ.
Akụkọ mmepe PON
Nchọpụta nkà na ụzụ PON malitere na 1995. N'October 1998, ITU nakweere ụkpụrụ nkà na ụzụ PON dabeere na ATM, G, nke òtù FSAN kwadoro (network access network). 983. A makwaara dị ka BPON (BroadbandPON). Ọnụego ya bụ 155Mbps ma nwee ike ịkwado 622Mbps na nhọrọ.
EFMA (Ethernetin the First Mile Alliance) webatara echiche nke Ethernet-PON (EPON) na njedebe nke 2000 na ọnụego nnyefe nke 1 Gbps na oyi akwa njikọ dabere na ntanetị Ethernet dị mfe.
Ndị otu FSAN tụpụtara GPON (Gigabit-CapablePON) na Septemba 2002, na ITU nakweere G na Maachị 2003. 984. 1 na G. 984. 2 nkwekọrịta. G. 984.1 A na-akọwapụta njirimara n'ozuzu nke usoro ịnweta GPON.G. 984. 2 na-akọwapụta nkesa anụ ahụ metụtara sublayer nke ODN (Optical Distribution Network) nke GPON. Na June 2004, ITU gafere G ọzọ. 984. 3, nke na-akọwapụta ihe ndị a chọrọ maka oyi akwa Transmission Convergence (TC).
Ntụnyere ngwaahịa EPON na GPON
EPON na GPON bụ isi akụkụ abụọ nke ohere netwọk anya, nke ọ bụla nwere uru nke ya, na-asọrịta mpi, na-akwado ibe ya na ịmụta ihe site na ibe ya. Ndị a na-atụnyere ha n'akụkụ dị iche iche:
Ọnụ ego
EPON na-enye uplink na downlink nke 1.25Gbps, na-eji akara ahịrị 8b/10b, na ọnụego ya bụ 1Gbps.
GPON na-akwado akara ule ọsọ ọsọ ma nwee ike ịkwado uplink na downlink ọsọ asymmetric, 2.5Gbps ma ọ bụ 1.25Gbps mgbada, na 1.25Gbps ma ọ bụ 622Mbps uplink. Dị ka ihe achọrọ n'ezie, a na-ekpebi ọnụọgụ uplink na downlink, na a na-ahọrọ modul ngwa anya kwekọrọ iji bulie oke ọnụ ahịa ngwa ngwa ngwa anya.
Nkwubi okwu a: GPON dị mma karịa EPON.
Oke nkewa
Oke nkewa bụ oleONU(ndị ọrụ) na-ebu otuOLTọdụ ụgbọ mmiri (ụlọ ọrụ).
Ọkọlọtọ EPON na-akọwa oke nkewa nke 1:32.
Ụkpụrụ GPON na-akọwa oke nkewa na 1:32; 1:64; 1:128
N'ezie, usoro EPON teknụzụ nwekwara ike nweta oke nkewa dị elu, dị ka 1: 64, 1: 128, usoro njikwa EPON nwere ike ịkwado karịa.ONU.The ụzọ ruru bụ tumadi ejedebeghị site arụmọrụ nkọwa nke ngwa anya modul, na nnukwu gbawara n'etiti ruru ga-eme ka ngwa anya modul na-eri ịrị elu budata. Na mgbakwunye, mfu ntinye PON bụ 15 ruo 18 dB, na nnukwu nkewa nkewa na-ebelata ebe nnyefe. Ọtụtụ bandwit nkekọrịta onye ọrụ bụkwa ọnụ ahịa nke oke nkewa.
Nkwubi okwu a: GPON na-enye ọtụtụ nhọrọ nhọrọ, mana nlebara anya ọnụ ahịa abụghị ihe doro anya. Oke kachasị anya nke sistemu GPON nwere ike ịkwado. Mgbe oke nkewa anya bụ 1:16, a ga-akwado oke anya anụ ahụ nke 20km. Mgbe oke nkewa anya bụ 1:32, a ga-akwado oke anya anụ ahụ nke 10km. EPON bụ otu,nkwubi okwu a: nhata.
QOS(Ọdịmma ọrụ)
EPON na-agbakwụnye 64-byte MPCP(multi point control protocol) na MAC nkụnye eji isi mee Ethernet nkụnye eji isi mee.MPCP njikwa ohere P2MP point-to-multipoint topology site na ozi, ala igwe, na oge iji mejuputa DBA dynamic bandwit òkè.The MPCP gụnyere na oke nkeONUohere nnyefe oge, nchọpụta akpaka na ịbanye nkeONU, na akuko nke nchikota na elu n'ígwé ka dynamically ekenye bandwit.MPCP na-enye isi nkwado maka P2MP topology. Agbanyeghị, protocol anaghị ekewa ihe ndị kacha mkpa ọrụ. Ọrụ niile na-asọ mpi maka bandwit na enweghị usoro. GPON nwere DBA zuru oke yana oke ọrụ QoS.
GPON na-ekewa usoro nkesa bandwit ọrụ n'ime ụdị anọ. Kachasị mkpa bụ nke edobere (Edozi), Nkwenye, Na-enweghị Nkwenye, na BestEffort. DBA gara n'ihu kọwapụta akpa okporo ụzọ (T-CONT) dị ka ngalaba nhazi oge okporo ụzọ, yana T-CONT ọ bụla bụ nke Alloc-ID na-achọpụta. T-CONT ọ bụla nwere ike ịnwe otu GEMPart-ID ma ọ bụ karịa. E kewara T-CONT n'ụdị ọrụ ise. Ụdị T-CONT dị iche iche nwere ụdị nhazi nke bandwidth dị iche iche, nke nwere ike izute ihe dị iche iche QoS chọrọ nke ọrụ dị iche iche na-aga maka igbu oge, jitter, na ọnụ ọgụgụ ọnwụ. oke-bandwidth (Edobere), dabara adaba maka ọrụ nwere mmetụta igbu oge, dịka ọrụ olu. A na-eji ụdị bandwit mara ụdị nke 2 site na bandwit edobere mana oghere oge enweghị njedebe. Oke bandwit ekwekọrịtara ekwekọrịtara (Assured) dabara adaba maka ọrụ bandwit edozi nke anaghị achọ nnukwu jitter, dị ka vidiyo na-achọ ọrụ. Ụdị 3 bụ nke e ji mara ya site na nkwa bandwidth opekempe na nkesa ike nke bandwidth na-adịghị arụ ọrụ, ma nwee njedebe nke bandwit kachasị elu, kwekọrọ na nkesa bandwidth na-ejighị n'aka (Na-enweghị Nkwenye), dabara maka ọrụ nwere ihe ndị chọrọ nkwa ọrụ yana nnukwu okporo ụzọ gbawara. Dị ka nbudata azụmahịa.Ụdị 4 ka e ji BestEffort mara, enweghị nkwa bandwidth, dabara maka ọrụ nwere obere latency na mkpa jitter, dị ka ọrụ nchọgharị WEB. Ụdị 5 bụ ụdị nchikota, mgbe ekenyechara n'aka na bandwidth na-abụghị nke a na-ekwe nkwa, mgbakwunye A na-ekenye bandwidth chọrọ dị ka o kwere mee.
Mmechi: GPON dị mma karịa EPON
Na-arụ ọrụ ma jikwaa OAM
EPON enweghị nlebara anya nke ukwuu maka OAM, kama ọ na-akọwa naanị ihe ngosi mmejọ ONT, loopback na njikọ njikọ, yana nkwado nhọrọ.
GPON na-akọwa PLOAM (PhysicalLayerOAM) na oyi akwa anụ ahụ, na OMCI (ONTMmanagementandControlInterface) na-akọwapụta na oyi akwa dị elu iji rụọ ọrụ nchịkwa OAM n'ọtụtụ ọkwa. A na-eji PLOAM emejuputa data ezoro ezo, nchọpụta ọkwa, na nlekota njehie. A na-eji protocol ọwa OMCI iji jikwaa ọrụ ndị oyi akwa dị elu kọwapụtara, gụnyere usoro paramita ọrụ nkeONU, ụdị na ọnụọgụ nke ọrụ T-CONT, paramita QoS, ozi nhazi arịrịọ na ọnụ ọgụgụ arụmọrụ, na-agwakwa ihe omume na-agba ọsọ nke usoro ahụ ozugbo iji mejuputa nhazi nkeOLTna ONT. Nlekọta nke nchọpụta mmejọ, arụmọrụ na nchekwa.
Mmechi: GPON dị mma karịa EPON
Njikọ oyi akwa mkpuchi na nkwado ọtụtụ ọrụ
Dị ka e gosiri na Figure 2, EPON na-agbaso usoro data Ethernet dị mfe, ma na-agbakwụnye 64-byte MPCP point-to-multipoint control protocol na Ethernet nkụnye eji isi mee mejuputa bandwit òkè, bandwit round-robin, na akpaka chọpụtara na usoro EPON. Ịgba ọsọ na ọrụ ndị ọzọ. Enweghị ọtụtụ nyocha na nkwado nke ọrụ na-abụghị ọrụ data (dị ka ọrụ mmekọrịta TDM). Ọtụtụ ndị na-ere ahịa EPON emepụtala ụfọdụ ngwaahịa na-abụghị ọkọlọtọ iji dozie nsogbu a, mana ha adịghị mma ma ọ na-esiri ike izute ihe QoS nke ụgbọelu chọrọ.
Ọgụgụ 2: Tụnyere nchịkọta GPON na EPON protocol
GPON gbadoro ụkwụ na akwa mkpuchi njem njem ọhụrụ (TC), nke nwere ike mezue mmegharị nke ọrụ dị iche iche dị elu. Dị ka egosiri na eserese 2, ọ na-akọwapụta ihe mkpuchi ATM na GFP encapsulation (protocol framing izugbe). Ị nwere ike ịhọrọ ha abụọ. Otu bụ maka encapsulation azụmahịa. N'ihi ewu ewu nke ngwa ATM ugbu a, GPON na-akwado naanị GFP encapsulation dị. Ngwa ngwa a malitere, na-ewepụ ATM na nchịkọta protocol iji belata ọnụ ahịa.
GFP bụ usoro oyi akwa njikọ ọnụ maka ọtụtụ ọrụ, nke ITU kọwara dị ka G. 7041. A na-eme mgbanwe dị nta na GFP na GPON, na PortID ka ewebatara na isi nke GFP frame iji kwado multi-port multiplexing. A na-ewebatakwa ihe ngosi nkebi Frag (iberibe) iji mee ka bandwidth dị irè nke sistemụ ahụ dịkwuo mma. Ọ na-akwado naanị ọnọdụ nhazi data maka ogologo data ogologo agbanwe ma ọ naghị akwado ọnọdụ nhazi data transperent maka ngọngọ data. GPON nwere ikike iburu ọtụtụ ọrụ dị ike. GPON's TC oyi akwa na-emekọrịta ihe, na-eji ọkọlọtọ 8 kHz (125μm) okpokolo agba ogologo, nke na-enye ohere GPON ịkwado oge ngwụcha ruo ọgwụgwụ yana ọrụ ndị ọzọ na-emekọrịta ihe, ọkachasị maka ịkwado ọrụ TDM ozugbo, nke a na-akpọ NativeTDM. GPON nwere nkwado “eke” maka ọrụ TDM.
Nkwubi okwu a: oyi akwa TC na-akwado GPON maka ọtụtụ ọrụ siri ike karịa MPCP nke EPON.
Mmechi
EPON na GPON nwere uru nke ha. GPON dị mma karịa EPON n'ihe ngosi arụmọrụ. Agbanyeghị, EPON nwere uru nke oge na ọnụ ahịa. GPON na-aga n'ihu. Ịtụ anya n'ihu ahịa ohere brọdband nwere ike ọ gaghị abụ nnọchi, ọ kwesịrị ịbụ nkwado. Maka bandwit, ọtụtụ ọrụ, QoS dị elu na nchekwa chọrọ, yana teknụzụ ATM dị ka onye ahịa azụ azụ, GPON ga-adaba adaba. Maka ndị ahịa nwere ọgụgụ isi dị ọnụ ala, QoS na nchekwa chọrọ, EPON abụrụla ihe kacha mkpa.