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  • 1. HC VIN CNG NGH BU CHNH VIN THNG TNG QUAN V VIN THNG (Dng cho sinh vin h o to i hc t xa) Lu hnh ni b H NI - 2007

2. HC VIN CNG NGH BU CHNH VIN THNG TNG QUANG V VIN THNG Bin son : Ths. Nguyn Vn t Ths. Nguyn Th Thu Hng Ks. L S t Ks. L Hi Chu 3. TNG QUAN V VIN THNG M s : 411TQV260 Chu trch nhim bn tho TRUNG TM O TO BU CHNH VIN THNG 1 (Ti liu ny c ban hnh theo Quyt nh s: /Q-TTT1 ngy ca Gim c Hc vin Cng ngh Bu chnh Vin thng) 4. LI NI U Trong nhng nm qua, h tng vin thng pht trin nhanh v c cng ngh v cht lng cung cp dch v. Vin thng tri qua mt qu trnh pht trin lu di vi nhiu bc ngot trong pht trin cng ngh v pht trin mng li. Vit Nam cng nh cc nc trn th gii, hin nay c rt nhiu nh khai thc vin thng khc nhau vi s a dng ca cng ngh v cu hnh mng cng nh cc dch v cung cp. c c ci nhn tng quan v vin thng ni chung, nm bt nhng kin thc c bn v vin thng v cng nm trong chng trnh o to ca h i hc t xa ca Hc vin Cng ngh Bu chnh Vin thng, cun ti liu Tng quan v vin thng c cc ging vin B mn Mng Vin thng, Khoa Vin thng I bin son. Ti liu gm 6 chng, trnh by nhng kin thc c bn v lch s pht trin ca vin thng, cc dch v vin thng, cc k thut c bn v truyn dn v chuyn mch trong vin thng cng vn bo hiu v ng b mng. Chng 1- Gii thiu chung: chng ny cung cp cho hc vin cch nhn tng quan v mng vin thng; qu trnh pht trin ca vin thng trong qu kh, hin ti v xu hng pht trin trong tng lai cng nh cc khi nim c bn trong vin thng c cp gip ngi c bc u hiu v vin thng ni chung v c s tip cn vi h thng vin thng phc tp. Chng 2- Dch v vin thng: chng ny cp n cc vn lin quan n dch v vin thng nh khi nim, cch thc phn loi dch v vin thng, cc yu t nh hng n cht lng dch v v cht lng mng, ng thi gii thiu v cc loi hnh dch v vin thng c bn v cc dch v mi trn th gii v Vit Nam, nhu cu v xu hng pht trin dch v vin thng. Chng 3- Cc mng vin thng: chng ny gii thiu s hnh thnh v pht trin ca cc mng vin thng: cc mng mng in thoi, cc loi mng v cng ngh mng truyn s liu, mng my tnh, Internet. Chng ny cn gii thiu nhng khi nim cn bn v cc phn t to nn mng vin thng, v quan im phn tng giao thc v cc phng thc chuyn giao thng tin qua cc mng c bn. Chng 4- Cc vn truyn dn v ghp knh. Chng 4 trnh by cc ni dung lin quan n truyn dn; khi nim v ghp knh v cc k thut ghp knh c s dng trong mng vin thng. Chng 5- Cc vn v chuyn mch v nh tuyn. Chng ny trnh by cc khi nim v chuyn mch knh, k thut chuyn mch thi gian v khng gian, s kt hp cc k thut trong cc h thng chuyn mch; K thut chuyn mch gi, nhng khi nim v nh tuyn v s phn loi chng cng c cp. Chng 6- Bo hiu v ng b trong mng vin thng: Chng ny a ra cc khi nim v cc k thut c bn v bo hiu; vai tr v cc gii php ng b mng v ng b trong mng vin thng Vit Nam (ca VNPT). 5. 2 phn u mi chng u c phn gii thiu v ni dung ca chng v ch r nhng kin thc c bn hc vin cn nm bt sau khi hc xong chng ny. Ngoi ra, gip sinh vin cng c kin thc hc, cui mi chng u c cc cu hi n tp. Cc cu hi c a ra di dng trc nghim, gip hc vin c th t nh gi nh phn hng dn tr li cui ti liu. y l ti liu cung cp cho cc hc vin h o to i hc t xa ca Hc vin Cng ngh Bu chnh Vin thng ni ring cng nh nhng ngi c mun tm hiu, tip cn v vin thng, mt trong nhng lnh vc cng ngh hin i v rt phc tp. Trong qu trnh bin son, chng ti lun c gng a ra nhng gii thch, v d n gin d hiu, tuy nhin khng th trnh khi nhng thiu st, rt mong cc hc vin, bn c thng cm v cho nhng gp . Nhng kin ng gp xin gi v : B mn Mng vin thng- Khoa Vin thng 1- Hc vin Cng ngh Bu chnh vin thng T: 84-34-515484, bomonmangVT1@yahoo.com H Ni, thng 8 nm 2006 6. 3 CHNG 1 - GII THIU CHUNG GII THIU CHNG Mc ch ca chng 1 l cung cp cho ngi c nhng khi nim c bn nht v vin thng, v qu trnh pht trin ca vin thng trong qu kh, hin ti v xu hng pht trin trong tng lai. Phn u chng 1 cp n lch s pht trin vin thng v nhng khi nim cn bn v thng tin, tn hiu v h thng truyn thng. Vn chun ha l mt ni dung rt quan trng trong vic nghin cu, tm hiu vin thng ni chung. Chng 1 trnh by cc ni dung lin quan n vn chun ha, trong gii thiu v cc t chc chun ha khc nhau. y l cc t chc chun ha quc gia, khu vc v quc t c nh hng rt ln ti cc nh sn xut thit b vin thng, cc nh khai thc vin thng v c khch hng s dng dch v vin thng. Hc vin cn phi nm c cc khi nim c bn v thng tin, tn hiu v h thng truyn thng; lch s pht trin vin thng v cc t chc chun ha vin thng quc t. 1.1 LCH S PHT TRIN CA VIN THNG Vin thng l mt trong nhng b phn kinh doanh pht trin nhanh nht trong cc cng ngh thng tin hin i. Ch cch y vi thp k, c coi l c hiu bit c bn v vin thng, ta ch cn nm bt c cch thc hot ng ca mng in thoi l . Ngy nay, lnh vc vin thng bao gm rt nhiu cng ngh v dch v hin i. Ngoi mt vi dch v hon thin nh dch v in thoi c nh cn c rt nhiu dch v v ang bng n nh dch v in thoi di ng v Internet. S xa b nhng quy nh trong nn cng nghip vin thng lm kinh doanh tng trng mc d gi c ca cc dch v ngy cng gim. Mi trng vin thng m mi ngi phi la chn hin nay kh l phc tp. Trc y, chng ta ch c mt la chn duy nht l c dng hay khng dch v ca mt nh cung cp dch v thoi duy nht. Ngy nay, c rt nhiu nh cung cp dch v cung cp dch v ADSL hoc modem cp cho truy nhp Internet v chng ta c th la chn mt trong s nhiu nh cung cp khi mun dng dch v thoi. Vin thng l ngun ti nguyn quan trng mang tnh chin lc cho hu ht cc tp on hin i v tm quan trng ca vin thng ngy cng gia tng. Mi trng vin thng lun lun thay i ny cho ta nhiu la chn mi v chng ta cn hiu v vin thng nhiu hn v tng qut hn c th tn dng c nhng kh nng sn c ngy nay. 1.1.1 Khi nim chung v vin thng Vin thng: bao gm nhng vn lin quan n vic truyn thng tin (trao i hay qung b thng tin) gia cc i tng qua mt khong cch, ngha l bao gm bt k hot ng lin quan ti vic pht/nhn tin tc (m thanh, hnh nh, ch vit, d liu, ) qua cc 7. 4 phng tin truyn thng (hu tuyn nh ng dy kim loi, cp quang hoc v tuyn hoc cc h thng in t khc). Hnh 1.1 l lc phn loi vin thng. Vin thng chim phn ch o trong truyn thng. Truyn thng l vic truyn thng tin t mt im ti mt im khc, gm c truyn thng c hc (bu chnh) v truyn thng in (vin thng) bi v n pht trin t dng c hc (my mc) sang dng in/quang v ngy cng s dng nhng h thng in/quang phc tp hn. Vin thng n hng Song hng Truyn thanh Truyn hnh Truyn hnh v tuyn Truyn hnh cp in bo Telex in thoi c nh in thoi di ng Truyn d liu Th in t Truyn hnh hi ngh Hnh 1.1: Vin thng T phn truyn thng c hc (th t, bo ch) ang c xu hng gim trong khi t phn truyn thng in/quang, c bit l truyn song hng, li gia tng v s chim th phn ch o trong tng lai. V vy, ngy nay nhng tp on bo ch cng ang tp trung v hng ti truyn thng in/quang, coi l c hi kinh doanh tng lai ca mnh. 1.1.2 Cc giai on pht trin vin thng Vin thng tri qua nhiu giai on lch s khc nhau. Hnh 1.2 cho ta nhng mc lch s pht trin quan trng trong vin thng, ch yu nhn mnh vo s pht trin v m rng ca cc h thng v dch v vin thng (chi tit hn v cc dch v c gii thiu trong Chng 2). C th phn s pht trin ca vin thng qua bn giai on chnh. Giai on th nht ko di khong 90 nm t khi in thoi ra i v pht trin. Giai on th hai l giai on xut hin chuyn mch SPC, truyn dn s v thng tin v tinh. Giai on th 3 l giai on pht trin c trng ca cc mng d liu v cng ngh chuyn mch gi. Giai on th 4 xut hin cng vn lin kt mng truyn thng. Phn tip theo trnh by nhng mc thi gian ng nh i theo nhng s kin ni bt lin quan ti vin thng (xem Ph lc 1 bit thm chi tit). - 1838-1866 in bo (telegraph): Samuel Morse hon thin h thng in bo ca chnh mnh; in bo l dch v vin thng u tin xut hin nm 1844. 8. 5 - 1876-1899 in thoi (telephony): Alexander Graham Bell pht minh ra in thoi (1876); xut hin tng i in thoi u tin vi 8 ng dy; Almond Strowger sng ch ra tng i c in kiu tng nc (step by step, 1887). - 1920-1928 Carson, Nyquist, Johnson v Hartley gii thiu l thuyt truyn dn. - 1923-1938 Truyn hnh (Television): H thng c hnh nh c thc hin; bt u nhng th nghim v thc nghim qung b. - 1937 Alec Reeves hnh thnh khi nim iu xung m (PCM). - 1938-1945 Cc h thng radar v viba pht trin trong i chin th gii ln th 2; FM c s dng rng khp trong truyn thng qun s. - 1948-1950 C.E. Shannon pht hnh cc bi bo nn tng v l thuyt thng tin. WAN: Mng din rng LAN: Mng ni ht WLAN: LAN khng dy WWW: World Wide Web ADSL: ng dy thu bao s bt i xng ISDN: Mng s tch hp a dch v AM: iu ch theo bin FM: iu ch theo tn s IP: Giao thc Internet CS: Chuyn mch knh PS: Chuyn gi VoD: Truyn video theo yu cu TV: Truyn hnh Hnh 1.2: S pht trin ca cc h thng v dch v vin thng - 1950 Ghp knh phn chia theo thi gian (TDM) c p dng vo in thoi. - 1953 Cc chun Tivi mu c cng b M. - 1955 J. R. Pierce xut cc h thng truyn thng v tinh. - 1962-1966 Dch v truyn d liu c thng mi; PCM chng t s thch hp cho truyn thoi v TV; l thuyt truyn dn s c pht trin. - 1965 Mariner IV truyn nhng bc nh t Sao Ha v Tri t. - 1976 Ethernet LAN do Metcalfe v Broggs (Xerox) sng ch. - 19701975 Chun PCM c CCITT trin khai. - 19801983 Khi ng ca Internet ton cu da trn giao thc TCP/IP. - 19801985 Cc mng di ng t bo hin i cung cp dch v; NMT Bc u, AMPS M, m hnh tham chiu OSI c T chc chun ha quc t (ISO) nh ngha. - 1989 Tim Berners-Lee (CERN) c ban u cho vn kin kt ni Web trn WWW (World Wide Web). 9. 6 - 19901997 H thng t bo s u tin, Global System for Mobile Communications (GSM), c thng mi v pht trin mnh trn ton th gii; S dng Internet v dch v m rng nhanh chng nh c WWW. - 19972001 Cng ng vin thng c bi b quy nh v kinh doanh pht trin nhanh chng; cc mng t bo s, c bit l GSM m rng trn ton th gii; nhng ng dng thng mi ca Internet m rng v mt phn truyn thng thoi truyn thng c chuyn t mng in thoi chuyn mch cng cng (PSTN) sang Internet; cht lng LAN c ci thin vi cng ngh Ethernet tin tin c tc ln ti tm Gigabit/s - 20012005 Truyn hnh s bt u thay th truyn hnh qung b tng t; cc h thng truy nhp bng rng m rng kh nng cung cp dch v Internet a phng tin ti mi ngi; dch v thoi tr thnh dch v truyn thng c nhn khi s xm nhp ca cc h thng t bo v PCS tng ln. - 2005 Truyn hnh s s thay th truyn hnh tng t v bt u cung cp cc dch v tng tc ngoi dch v qung b; cc h thng di ng t bo th h th 3 v cc cng ngh WLAN s cung cp cc dch v d liu tin tin cho ngi s dng di ng; cc dch v di ng ni ht s m rng, ng dng cho nhng cng ngh khng dy khong cch ngn trong nh v cng s s tng ln; mng vin thng ton cu s tin trin hng ti mt bng mng chuyn mch gi chung cho tt c cc