Cibiyar sadarwar tarho ta al'ada murya ce ta hanyar musanyawa, watsa shirye-shiryen watsa shirye-shiryen da ake buƙata na 64kbit/s. Abin da ake kira VoIP shine cibiyar sadarwar musayar fakitin IP azaman dandamali na watsawa, damfara siginar siginar murya, marufi da jerin aiki na musamman, ta yadda zai iya amfani da ka'idar UDP da ba ta da alaƙa don watsawa.
Ana buƙatar abubuwa da ayyuka da yawa don watsa siginar murya akan hanyar sadarwar IP. Mafi sauƙi nau'i na hanyar sadarwa ya ƙunshi na'urori biyu ko fiye da ke da damar VoIP waɗanda aka haɗa ta hanyar hanyar sadarwa ta IP.
1. Canjin Murya-Data
Siginar murya siginar siginar analog ne, ta hanyar IP don watsa murya, ko kasuwancin aikace-aikacen lokaci-lokaci ko kasuwancin aikace-aikacen lokaci-lokaci, na farko zuwa canjin siginar analog na bayanan siginar, wato siginar muryar analog 8 ko 6 ƙididdigewa, sannan a aika zuwa ma'ajiyar buffer. , Za a iya zaɓar girman buffer bisa ga buƙatun jinkirta da coding. Yawancin maƙallan ƙananan ramuka masu ƙima suna ɓoye a cikin firam.
Tsawon firam na al'ada ya kasance daga 10 zuwa 30 ms. Idan aka yi la'akari da farashin lokacin watsawa, fakitin harsuna yawanci sun ƙunshi 60, 120, ko 240ms na bayanan magana. Ana iya aiwatar da digitization ta amfani da tsare-tsaren coding na murya daban-daban, kuma ma'auni na coding murya na yanzu sun fi ITU-T G.711. Mai rikodin murya a inda ake nufi dole ne ya aiwatar da algorithm iri ɗaya domin na'urar magana da ke wurin zata iya dawo da siginar magana ta analog.
2.Original data-to-IP hira
Da zarar an ƙididdige siginar magana ta lambobi, mataki na gaba shine a damfara ɓoye fakitin magana tare da takamaiman tsayin firam. Yawancin masu rikodin suna da takamaiman tsayin firam. Idan encoder yana amfani da firam 15ms, fakitin 60ms daga farko an raba shi zuwa firam huɗu kuma an rufa masa asiri a jere. Kowane firam yana da samfuran magana 120 (yawan samfurin 8kHz). Bayan rufaffiyar, an haɗa firam ɗin huɗun da aka matsa zuwa cikin kunshin magana da aka matsa kuma an aika zuwa mai sarrafa cibiyar sadarwa. Mai sarrafa hanyar sadarwa yana ƙara Baotou, sikelin lokaci, da sauran bayanai zuwa muryar kuma ya wuce shi zuwa ɗayan ƙarshen ta hanyar hanyar sadarwa.
Cibiyar sadarwar magana kawai tana kafa haɗin jiki tsakanin wuraren ƙarshen sadarwa (layi ɗaya) kuma tana watsa sigina masu rufaffiyar tsakanin wuraren ƙarshen. Ba kamar cibiyoyin sadarwar da'ira ba, cibiyoyin sadarwar IP ba sa yin haɗi. Yana buƙatar a sanya bayanai a cikin madaidaitan rahotanni ko fakiti masu tsayi, sannan adireshi da sarrafa bayanai zuwa kowane datagram kuma a aika ta hanyar hanyar sadarwa, tura zuwa wurin da aka nufa.
3. Canja wurin
A cikin wannan tashar, ana kallon duk hanyar sadarwa azaman fakitin murya da aka karɓa daga shigarwar sannan kuma a tura shi zuwa fitarwar cibiyar sadarwa cikin ƙayyadadden lokaci (t). t na iya bambanta a cikin cikakken kewayo, yana nuna jitter a watsawar hanyar sadarwa.
Kullin guda ɗaya a cikin hanyar sadarwar yana bincika bayanan adireshin da ke da alaƙa da kowane bayanan IP kuma yana amfani da wannan bayanin don tura waccan bayanan zuwa tasha ta gaba akan hanyar da za a nufa. Hanyar hanyar sadarwa na iya zama kowane topology ko hanyar samun damar da ke goyan bayan rafukan bayanan IP.
4.The IP kunshin - da canji na bayanai
Na'urar VoIP mai zuwa tana karɓar wannan bayanan IP kuma ta fara aiki. Matakan cibiyar sadarwa yana ba da madaidaicin tsayin daka da ake amfani da shi don daidaita jitter ɗin da hanyar sadarwa ta haifar. Buffer na iya ɗaukar fakitin murya da yawa, kuma masu amfani za su iya zaɓar girman ma'ajin. Ƙananan buffers suna samar da ƙarancin latency, amma ba sa tsara babban jitter. Na biyu, na'urar tantancewa tana buɗe fakitin magana don samar da sabon kunshin magana, kuma wannan ƙirar kuma tana iya aiki ta firam, daidai tsayin da na'urar.
Idan tsayin firam ɗin ya kasance 15ms, fakitin muryar 60ms ana raba su zuwa firam 4, sa'an nan kuma a canza su zuwa madaidaicin bayanan murya na 60ms kuma a aika zuwa buffer na yanke hukunci. A yayin aiwatar da rahoton bayanan, ana cire bayanin adireshi da sarrafawa, ana adana ainihin bayanan asali, sannan ana bayar da wannan ainihin bayanan ga mai yankewa.
5.An canza magana ta dijital zuwa magana analog
Tushen sake kunnawa yana cire samfuran muryar (480) a cikin ma'ajin kuma aika su zuwa katin sauti ta lasifikar da aka ƙididdige mitar (misali 8kHz). A takaice dai, watsa siginar murya akan hanyar sadarwar IP yana tafiya ta hanyar juyawa daga siginar analog zuwa siginar dijital, marufi na dijital a cikin fakitin IP, watsa fakitin IP ta hanyar hanyar sadarwa, fakitin fakitin IP da dawo da muryar dijital zuwa analog. sigina.
Na biyu, matakan fasaha masu alaƙa da VoIP
Don aikace-aikacen multimedia akan cibiyoyin sadarwar da ake da su, Ƙungiyar Sadarwar Sadarwa ta Duniya (ITU-T) ta ƙirƙira ka'idar tsarin sadarwa ta Multimedia H.32x, manyan ma'auni masu zuwa don bayani mai sauƙi:
H.320, Standard for multimedia sadarwa a kan narrowband video tarho tsarin da m (N-ISDN);
H.321, Standard don sadarwar multimedia akan B-ISDN;
H.322. Matsayi don sadarwar multimedia akan LAN wanda QoS ya lamunce;
H.323. Daidaitaccen sadarwar multimedia akan hanyar sadarwa ta sauya fakiti ba tare da garantin QoS ba;
H.324, ma'auni don sadarwar multimedia akan ƙananan hanyoyin sadarwa na ƙananan kuɗi (PSTN da hanyar sadarwa mara waya).
Daga cikin ma'auni na sama, H. The 323 Standard-defined networks su ne mafi yadu amfani, kamar Ethernet, Token Network, FDDI Network, da dai sauransu.Saboda H.A aikace-aikace na 323 misali ya halitta ya zama wani zafi tabo a kasuwa. Don haka a ƙasa za mu mai da hankali kan H.323.H.323 An bayyana manyan abubuwa guda huɗu a cikin tsari: Terminal, ƙofa, software na sarrafa kofa (wanda aka fi sani da gateway ko gate), da naúrar sarrafa maki mai yawa.
1. Tashar (Terminal)
Duk tashoshi dole ne su goyi bayan sadarwar murya, kuma damar sadarwar bidiyo da bayanan na zaɓi ne.duk H. Dole ne tashar ta 323 ta goyi bayan Standard H.245, H.245 Ana amfani da ma'auni don sarrafa amfani da tashar da aikin tashar.H. .323 Babban sigogi na codec na magana a cikin sadarwar murya an ƙayyade kamar haka: ITU shawarar bandwidth murya / KHz watsa bit rate / Kb / s matsawa algorithm annotation G.711 3.4 56,64 PCM sauki matsawa, shafi PSTN a G .728 3.4 16 LD-CELP ingancin murya kamar yadda G.711, kamar yadda aka yi amfani da shi zuwa ƙananan ƙananan watsawa G.722 7 48,56,64 ADPCM ingancin murya ya fi G.711, da aka yi amfani da shi zuwa babban saurin watsawa G. .723.1G.723.0 3.4 6.35.3 LP-MLQ ingancin murya abin karɓa ne, G.723.1 Dauki G don dandalin VOIP.729G.729A 3.4 8 CS-ACELP jinkiri ya yi ƙasa da G.723.1, ingancin murya ya fi girma fiye da na VOIP. G.723.1.
2. Gateway (Gateway)
Wannan shine zaɓi na H.An don tsarin 323. Ƙofar na iya canza ladabi, audio, video codeing algorithms da kuma siginar sarrafawa da aka yi amfani da su ta hanyar tsarin daban-daban don ƙaddamar da tsarin sadarwa ta tashar.Kamar PSTN-tushen H.324 System da kunkuntar. ISDN na tushen H.The 320 System da H.323 Don tsarin sadarwa, ya zama dole don saita ƙofar;
3.Tsarin kwastan (Mai tsaron ƙofar)
Wannan shi ne H.Abin zaɓi na tsarin 323 shine software don kammala aikin gudanarwa. Yana da manyan ayyuka guda biyu: na farko shine H.323 Application management; na biyu shine gudanar da hanyar sadarwa ta tashar ta hanyar ƙofa (kamar kafa kira, cirewa, da dai sauransu) .Mai gudanarwa na iya yin fassarar adireshi, sarrafa bandwidth, tabbatar da kira, rikodin kira, rajistar mai amfani, sarrafa yankin sadarwa da sauran ayyuka ta hanyar kwastan. keeping.one H.323 Yankin sadarwa na iya samun ƙofofi da yawa, amma ƙofa ɗaya ce kawai ke aiki.
4.Multipoint iko naúrar (Multipoint Control Unit)
MCU tana ba da damar sadarwa mai ma'ana da yawa akan hanyar sadarwar IP, kuma ba a buƙatar sadarwa mai nuni zuwa ma'ana. Duk tsarin yana samar da topology tauraro ta hanyar MCU. MCU yana ƙunshe da manyan abubuwa guda biyu: Multipoint controller MC da multipoint processor MP, ko ba tare da MP.H ba tsakanin tashoshin sarrafa MC.245 Sarrafa bayanai don gina ƙaramin sunan jama'a don sarrafa sauti da bidiyo.MC ba ya sarrafa duk wani rafi na bayanan kafofin watsa labarai kai tsaye, sai dai ya bar shi zuwa MP. MP yana gaurayawa, kunnawa, da sarrafa sautin. , bidiyo, ko bayanan bayanai.
A cikin masana'antar akwai tsarin gine-gine guda biyu masu kama da juna, daya shine ITU-T H da aka gabatar a sama.323 Protocol shine ka'idar SIP (RFC2543) wanda Cibiyar Injiniya ta Intanet (IETF) ta gabatar, kuma ka'idar SIP ta fi dacewa da tashoshi masu hankali.
Na uku, Ƙarfafa haɓakar VoIP
Yin amfani da VoIP da yawa zai zama gaskiya da sauri saboda yawancin kayan aiki, software, abubuwan da suka shafi ci gaba da fasaha a cikin yarjejeniya da ka'idoji. Ci gaban fasaha da ci gaba a cikin waɗannan fagagen suna taka rawa wajen ƙirƙirar hanyar sadarwa ta VoIP mafi inganci, aiki da aiki. Abubuwan fasaha waɗanda ke haɓaka saurin haɓakawa har ma da yaɗuwar aikace-aikacen VoIP ana iya taƙaita su cikin waɗannan abubuwan.
1.Digital Signal Processor
Na'urori masu sarrafa sigina na ci gaba (Digital Signal Processor, DSP) suna aiwatar da abubuwan da ake buƙata don haɗa murya da bayanai. Ƙarfin sarrafawa tare da ƙananan farashi yana sa DSP ya dace don yin ayyukan sarrafa sigina a cikin tsarin VoIP.
Rafin murya guda ɗaya akan G.729 Farashin ƙididdiga na matsar murya yawanci babba, yana buƙatar 20MIPS. Idan ana buƙatar CPU ta tsakiya don aiwatar da ayyukan tafiyar da tsarin aiki yayin sarrafa rafukan murya da yawa, wannan ba gaskiya bane. Sabili da haka, yin amfani da ɗaya ko fiye DSP na iya cire aikin kwamfuta na hadaddun matsawar murya algorithm daga tsakiyar CPU. Bugu da ƙari, DSP ya dace da gano ayyukan murya da sokewar amsawa, yana ba su damar aiwatar da rafukan bayanan murya a cikin ainihin lokaci kuma da sauri samun dama. Ƙwaƙwalwar kan jirgi, don haka. A cikin wannan sashe, muna dalla-dalla yadda ake aiwatar da coding na murya da sokewar amsawa akan dandalin TMS320C6201DSP.
Protocol da daidaitattun software da hardware H.323 Hanya madaidaiciya madaidaiciya DSP MPLS tag musayar nauyi bazuwar farkon ganowa ci-gaba ASIC RTP, RTCP dual mazurari babban adadin cell algorithm DWDM RSVP rated damar samun sauri kudi SONET Diffserv, CAR Cisco sauri isar da CPU sarrafa ikon G. 729, G.729a: CS-ACELP Extended Access Tebur ADSL, RADSL, SDSL FRF.11/FRF.12 Token ganga algorithm Multilink PPP Frame Relay Data rectifier SIP dangane da fifikon haɗin CoS Packet akan SONET IP da ATM QoS / CoS
2.Advanced sadaukar hadedde da'irori
Aikace-aikacen da aka haɗa da shi (ASIC) ci gaba ya samar da sauri, mafi rikitarwa, da kuma ƙarin aiki na yau da kullun ko ƙaramin aikin da ke da alaƙa da kunkuntar kwallaye. ana iya inganta su sosai don takamaiman ayyuka, yawanci tare da maƙasudi guda biyu CPU ɗaya ko umarni da yawa na girma cikin sauri.
Kamar dai yadda guntu na Instruction Set Computer (RSIC) ke mayar da hankali kan saurin aiwatar da lambobi masu iyaka, an tsara ASIC don aiwatar da ayyuka masu iyaka da sauri.Da zarar an gama haɓakawa, farashin samar da taro na ASIC ya ragu, kuma ana amfani dashi. don na'urorin sadarwar ciki har dahanyoyin sadarwada masu sauyawa, yin ayyuka irin su duba tebur na tuƙi, ƙaddamar da rukuni, rarraba rukuni da dubawa, da kuma layi. Yin amfani da ASIC yana ba da na'urar aiki mafi girma da ƙananan farashi. Suna samar da ƙarar broadband da mafi kyawun goyon bayan QoS ga cibiyar sadarwa, don haka suna wasa. muhimmiyar rawa wajen inganta ci gaban VoIP.
3.IP fasahar watsawa
Yawancin cibiyoyin sadarwar sadarwar watsawa suna amfani da rarrabuwar lokaci-lokaci, yayin da Intanet dole ne ta ɗauki sake amfani da ƙididdiga da musayar fakiti mai tsayi. Idan aka kwatanta, na karshen yana da yawan amfani da albarkatun cibiyar sadarwa, sauƙi mai sauƙi da tasiri mai mahimmanci, kuma yana da amfani sosai ga ayyukan bayanai, wanda shine daya daga cikin muhimman dalilai na ci gaba da sauri na Intanet. Duk da haka, sadarwar sadarwar IP mai watsa shirye-shiryen yana buƙatar QoS da halayen jinkiri. , don haka ci gaban ƙididdiga na musayar fakitin multixing ya jawo damuwa. A halin yanzu, ban da sabon ƙarni na yarjejeniyar IP-IPV6, ƙungiyar aikin injiniya ta Intanet ta duniya (IETF) ta ba da shawarar fasahar musaya ta lamba mai yawa (MPLS), wannan. wani nau'i ne na zaɓin layin hanyar sadarwa wanda ya dogara da alamar tag / lakabi daban-daban, na iya inganta sassaucin zaɓin hanya, faɗaɗa ikon zaɓin layin hanyar sadarwa, sauƙaƙena'ura mai ba da hanya tsakanin hanyoyin sadarwada haɗin haɗin yanar gizon musanya, inganta aikin cibiyar sadarwa.MPLS na iya aiki a matsayin ka'idar zirga-zirga mai zaman kanta, kuma mai jituwa tare da ka'idodin hanyar sadarwa na yanzu, tallafawa ayyuka daban-daban, gudanarwa da ayyukan kulawa na cibiyar sadarwar IP, sa QoS, ƙaddamarwa, aikin sigina ya inganta sosai, don isa ko kusa da matakin ƙididdiga na sake amfani da tsayayyen fakitin musayar fakiti (ATM), kuma mai sauƙi, inganci, arha kuma mai amfani fiye da ATM.
Har ila yau, IETF a cikin gida yana fahimtar sabuwar fasahar haɗakarwa, don cimma nasarar zaɓin hanyar QoS. Ana nazarin "fasaha na rami" don cimma nasarar watsa hanyoyin sadarwa ta hanyar sadarwa guda ɗaya. Bugu da ƙari, yadda za a zabi dandalin watsa shirye-shiryen IP shine ma muhimmin filin bincike a cikin 'yan shekarun nan, da IP akan ATM, IP akan SDH, IP akan DWDM da sauran fasaha sun bayyana a jere.
Layin IP yana ba wa masu amfani da IP damar samun damar yin amfani da IP masu inganci tare da wasu garantin sabis.Mai amfani da mai amfani yana ba da hanyar samun damar (IP access da broadband access) da kuma nau'in abun ciki na sabis.A cikin tushe na asali, Ethernet, a matsayin Layer na jiki. hanyar sadarwar IP, al'amari ne na hakika, amma IP overDWDM yana da sabuwar fasaha, kuma yana da babban damar ci gaba.
Dense Wave Division MultipLexing (DWDM) injects sabuwar rayuwa a cikin fiber cibiyoyin sadarwa da kuma samar da ban mamaki bandwidth a cikin telecom kamfanonin kwanciya sabon fiber backbone.DWDM fasaha utilizes da capabilities na Tantancewar zaruruwa da kuma ci-gaba Tantancewar watsa kayan aiki.The sunan kalaman division multiplexing aka samu don watsa mahara mahara. Tsawon raƙuman haske na haske (LASER) daga rafi guda ɗaya na fiber na gani. Tsarin halin yanzu na iya aikawa da gane 16 raƙuman raƙuman ruwa, yayin da tsarin gaba zai iya tallafawa 40 zuwa 96 cikakkun maɗaukaki. don haka fadada hanyar sadarwar 2.6 Gbit/s (OC-48) da sau 16 ba tare da sanya sabbin zaruruwa ba.
Yawancin sababbin hanyoyin sadarwa na fiber suna gudanar da OC-192 a (9.6 Gbit / s), suna samar da damar sama da 150 Gbit / s akan nau'i biyu na fibers lokacin da aka haɗa su tare da DWDM. Bugu da ƙari, DWDM yana ba da ka'idar dubawa da siffofi masu zaman kansu na sauri, kuma suna goyan bayan ATM guda biyu. , SDH da Gigabit Ethernet watsa siginar siginar a kan fiber guda ɗaya, wanda zai iya dacewa da hanyoyin sadarwa na yanzu, don haka DWDM zai iya kare dukiyar da ke ciki, amma kuma ya samar da ISP da kamfanonin sadarwa tare da kashin baya mai karfi, da kuma sanya broadband kasa da tsada kuma mafi dacewa, wanda ke ba da damar yin amfani da shi. goyon baya mai ƙarfi don buƙatun bandwidth na mafita na VoIP.
Ƙarfafa yawan watsawa ba zai iya samar da bututun da ke da ƙarancin toshewa ba, har ma ya rage jinkiri da yawa, don haka zai iya rage buƙatun QoS akan hanyoyin sadarwar IP.
4.Broadband fasaha fasaha
Samun damar mai amfani da hanyar sadarwar IP ya zama ƙugiya mai hana ci gaban duk hanyar sadarwa.A cikin dogon lokaci, babban burin samun damar mai amfani shine fiber-to-gida (FTTH). da kuma m Tantancewar cibiyar sadarwa.Tsohon ne yafi a Amurka, hade da bude baki V5.1/V5.2, watsa da hadedde tsarin a kan Tantancewar fiber, nuna babban vitality.
Na karshen yana cikin tsari kuma a cikin Jamus. Fiye da shekaru goma, Japan ta ɗauki jerin matakai don rage farashin hanyoyin sadarwa na gani zuwa matakin kama da igiyoyi na jan karfe da murɗaɗɗen ƙarfe, kuma suna amfani da shi.Musamman. A cikin 'yan shekarun nan, ITU ya ba da shawarar hanyar sadarwa ta ATM-based passive Optical Network (APON), wanda ya dace da fa'idodin ATM da kuma hanyar sadarwa mai mahimmanci. Matsakaicin damar shiga zai iya kaiwa 622 M bit / s, wanda ke da matukar fa'ida ga haɓaka sabis ɗin multimedia na IP na broadband, kuma yana iya rage ƙarancin gazawar da adadin nodes, da faɗaɗa ɗaukar hoto. A halin yanzu, ITU ta kammala aikin daidaitawa. , masana'antun suna haɓaka haɓakawa sosai, za a sami kayayyaki a kasuwa, za su zama babban jagorar ci gaba na fasahar samun damar faɗaɗa don ƙarni na 21st.
A halin yanzu, manyan fasahohin shiga su ne: PSTN, IADN, ADSL, CM, DDN, X.25 da Ethernet da kuma ginshiƙin tsarin shiga mara waya ta broadband, da dai sauransu.Wadannan fasahohin shiga suna da halayensu, ciki har da ADSL da CM masu tasowa mafi sauri; CM (Cable Modem) yana amfani da kebul na coaxial, babban adadin watsawa, ƙarfin hana tsangwama mai ƙarfi; amma ba watsa ta hanyoyi biyu ba, babu daidaitattun daidaito. ADSL (Asymmetrical Digital Loop) yana da keɓantaccen damar yin amfani da na'ura mai ba da hanya tsakanin hanyoyin sadarwa, yana yin cikakken amfani da hanyar sadarwar wayar da ake da ita da kuma samar da ƙimar watsawar asymmetric. Matsakaicin zazzagewar a gefen mai amfani zai iya kaiwa 8 Mbit/s, kuma yawan lodawa a gefen mai amfani zai iya kaiwa 1M bit/s.ADSL yana ba da buɗaɗɗen buɗaɗɗen buɗaɗɗen da ake buƙata don kasuwanci da duk masu amfani, kuma yana rage tsada sosai.Yin amfani da ADSL mai rahusa da'irori na yanki, kamfanoni yanzu suna samun damar Intanet da VPN na tushen Intanet a cikin sauri mafi girma, yana ba da damar mafi girman ƙarfin kiran VoIP.
5.Central sarrafawa naúrar fasaha
Ƙungiyoyin sarrafawa na tsakiya (CPU) suna ci gaba da samuwa a cikin aiki, iko, da sauri.Wannan yana ba da damar yin amfani da aikace-aikacen multimedia PC kuma yana inganta aikin ayyukan tsarin da aka iyakance ta hanyar CPU power.The PC's ikon aiwatar da rafi audio da bidiyo bayanai an dade ana jira. ta masu amfani, don haka isar da kiran murya akan cibiyoyin sadarwar bayanai shine manufa ta gaba. Wannan fasalin na'ura mai kwakwalwa yana ba da damar duka aikace-aikacen tebur na multimedia da ci-gaba a cikin abubuwan cibiyar sadarwa don tallafawa aikace-aikacen murya.