Bai Giang Chuong 1 Tong Quan He Thongtruyen Dan

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  • 1Bi ging

    K thuttruyn dn 1

    Ging vin: ThS. Phan Thanh Hin

  • 2Vai tr - V tr mn hc1. Vai tr:

    1. Cung cp kin thc tng quan v h thng truyn dns

    2. Cc thng s c bn trong knh truyn dn s.3. Cc k thut truyn dn s in hnh ( PDH, SDH,)4. Cc m hnh qun l mng truyn dn.

    2. V tr mn hc:1. Cc mn hc tin quyt: C s thng tin s; L thuyt

    thng tin; K thut mch in t2. Cc mn hc song hnh: Thng tin vi ba s, Mng my

    tnh; K thut truyn hnh

  • 3Hnh thc hc nh gi1. Yu cu: i hc y ( khng ngh qu s tit quy nh) Chun b bi trc khi n lp. Chun b gio trnh v ti liu tham kho

    2. nh gi:1. Kim tra gia k: Thi vit2. Thi kt thc hc phn: Thi vit3. im chuyn cn: Sinh vin c th ng k lm tiu

    lun,

  • 4Ti liu hc tpSch, gio trnh chnh: [1]; Nguyn Quc Bnh; K thut truyn dn s; NXB

    Qun i nhn dn; 2001. [2]; Chu Cng Cn; K thut truyn dn SDH; NXB Giao

    thng vn ti; 2003. [3]; Nguyn Hng Sn; K thut truyn s liu; NXB Lao

    ng - X hi; 2002. Sile bi ging, ti liu km theo. - Sch tham kho: [4]; Nguyn Thc Hi; Mng my tnh v cc h thng

    m; NXB Gio dc; 1997.

  • 5Ni dung mn hc Chng 1: Tng quan v h thng truyn dn Chng 2: S ho tn hiu lin tc trong cc h thng

    truyn dn s.

    Chng 3: Ghp knh trong truyn dn tn hiu s Chng 4: X l tn hiu bng gc Chng 5: K thut truyn dn PDH Chng 6: K thut truyn dn SDH Chng 7: ng b trong truyn dn s

  • 6CHNG 1

    TNG QUAN V H THNG TRUYN DN

  • 7Ni dung chnh

    1. Cc c im ca h thng thng tin s

    2. Trnh by mt s khi nim v thut ng

    3. S khi h thng thng tin s c bn

    4. Cc tham s cht lng c bn ca h thng thng tin s

    5. H thng truyn dn s

    6. Dch v mng vin thng v mi trng truyn

  • 81. Cc c im h thng thng tin s

    Cc h thng thng tin s c dng truyn tin tc tni ny n ni khc.

    Bn tin l dng hnh thc cha ng thng tin ( C thlin tc hay ri rc)

    Biu din vt l ca mt bn tin c gi l tn hiu. Tn hiu truyn dn c th l: Tn hiu Analog Tn hiu s

  • 92. MT S KHI NIM V THUT NG

    Tm lc mt s kin thc c bn :Khi nim v thut ngTn hiu v nhiu

  • 10

    Tn hiu

  • 11

    Tn hiu

  • 12

    T

    A

    Tn s ca tn hiuMin thi gian Min tn s

    A

    T

    T

    A

    1 giy (s)

    f

    A

    A

    A

    0

    f

    2f

    F

    F

    F

  • 13

    Ph ca tn hiu

    f = 300 Hz 300F (Hz)

    600 Hz 600F (Hz)

    700 Hz 700F (Hz)

    F (Hz)

    Ph: Tm tn s cha trong tn hiu

  • 14

    Bng thngA

    F500 2500

    Bng thng tuyt i rng ph (c o bng s chnh lch tn s cao nht v thp nht

    m knh h tr) Bng thng cng ln, tc truyn cng cao

    Bng thng hiu dng Bng thng Di tm tn s hp cha hu ht nng lng ca t/h

    Bandwidth = 2500 500 = 2000 Hz

  • 15

    Ph m ca thoi

  • 16

    Nhiu Tn hiu thm vo gia thit b pht v thit b thu Cc loi nhiu Nhiu nhit Nhiu iu ch Nhiu xuyn knh (cross talk) Nhiu xung

  • 17

    Nhiu

  • 18

    Nhiu nhit Do dao ng nhit ca cc in t trong cht dn Hm ca nhit

    Phn tn ng nht trn ph tn s Nhiu trng Khng th loi b gii hn hiu sut ca h thng Nhiu trong bng thng 1Hz ca bt k cht dn no

    N0 = kT N0: mt cng sut nhiu (watt/Hz) k: hng s Boltzmann (= 1.38 x 10-23 J/0K) T: nhit (0K)

    Nhiu trong bng thng W Hz: N = N0W = kTW

  • 19

    Nhiu Nhiu iu ch

    T/h nhiu c tn s l tng hoc hiu tn s ca cc t/h dng chungmi trng truyn

    Do tnh phi tuyn ca thit b thu/pht Nhiu xuyn knh (crosstalk)

    T/h t ng truyn ny nh hng sang cc ng truyn khc Cng ln (hoc nh hn) nhiu nhit

    Nhiu xung Xung bt thng (spike)

    e.g. nh hng in t bn ngoi Thi khong ngn Cng cao nh hng nhiu n qu trnh trao i d liu s

    Xung 0.01s lm mt 50 bit d liu nu truyn tc 4800bps

  • 20

    Tc knh truyn (kh nng knh) c im C th truyn nhiu hn mt bit ng vi mi thay i ca

    tn hiu trn ng truyn. Tc truyn thng tin cc i b gii hn bi bng thng

    ca knh truyn Cng thc Nyquist Nu tc truyn tn hiu l 2W th tn hiu vi tn s nh

    hn (hoc bng) W l ; ngc li nu bng thng l W th tc tn hiu cao nht l 2W

    C = 2W x log2M C : tc truyn t/h cc i (bps) khi knh truyn khng c

    nhiu W : bng thng ca knh truyn (Hz) M : s mc thay i tn hiu trn ng truyn

    hu hiu bng thng: B = R/W (bps HZ-1)

  • 21

    Tc knh truyn

  • 22

    Tc knh truyn

  • 23

    Tc d liu Baud rate (baud/s)

    Nghch o ca phn t d liu ngn nht (s ln thay i tn hiung truyn mi giy)

    Tn hiu nh phn tc 20Hz: 20 baud (20 thay i mi giy) Bit rate (bps hoc bit/s)

    c trng cho kh nng ca knh truyn Tc truyn d liu cc i trong trng hp khng c nhiu Bng baud rate trong trng hp tn hiu nh phn Khi mi thay i ng truyn c biu din bng 2 hay nhiu bit,

    tc bit khc vi tc baud Quan h gia Baud rate v Bit rate

    R = Rs x log2M = Rs x m R : tc bit (bit/s) Rs : tc baud (baud/s) M : s mc thay i tn hiu trn ng truyn m : s bit m ha cho mt tn hiu

  • 24

    Bit rate

  • 25

    T l tn hiu so vi nhiu Signal to Noise ratio

    SNR = 10 x log10 (S/N) (dB) S : cng sut tn hiu nhn N : cng sut nhiu

    Cng thc Shannon-HartleyC = W x log2 (1 + S/N) (bps)

    C: tc truyn t/h cc i khi knh truyn khng c nhiu

  • 26

    Chiu di sng Khong cch chim bi mt chu k Khong cch gia 2 im pha tng ng trong 2 chu k

    lin tip K hiu Gi s vn tc t/h l v = vT f = v c = 3*108 ms-1 (tc nh sng)

  • 27

    3. S khi h thng thng tin s

    To khun

    To khun

    M ho ngun

    Gii m ngun

    M ho mt

    Gii m mt

    M ho khnh

    Gii m khnh

    iu ch

    Phn khnh

    Ghp khnh

    Gii iu ch

    Tri ph

    Gii tri ph

    a truy nhp

    a truy nhp

    My pht

    My thu

    Knh truyn

    ng b

    T cc ngun khc

    Ti cc ch khc

    T ngun tin

    Ti b nhn tin

    * * * * *

    * * * * *

    * : Chui bt

    # # #

    ###

    #: Chui dng sng

    y l s h thng thng tin s in hnh song khng phi nht thit hthng no cng phi thc hin y cc thut ton c bn ny.

  • 28

    Chc nng cc khi trong s

    To khun dng tn hiu: thc hin bin i tn tc cntruyn th hin dng tn hiu lin tc hay s thnh ccchui bit nh phn.

    M ho v gii m ngun tn hiu: thc hin nn v giinn tn hiu nhm gim tc bit gim ph tn hiu.

    M mt: thc hin m chui bit theo 1 kho xc nhnhm bo mt tin tc.

    M knh: chng nhiu v cc tc ng xu khc trnng truyn.

  • 29

    Chc nng cc khi trong s Ghp, tch knh: thc hin truyn tin t nhiu ngun tin

    khc nhau ti cc ch nhn tin khc nhau trn 1 h thngtruyn dn.

    iu ch (MODEM) l bin i tn hiu t bng tn c ssang tn hiu thch hp vi ng truyn dn.

    Tri ph: nhm mc ch chng nhiu v bo mt tin tc. a truy nhp: cho php nhiu i tng c th truy nhp

    mng thng tin s dng h thng truyn dn theo yucu.

    ng b mng: bao gm ng b nhp v dng b sngmang

  • 30

    4. Cc tham s c trng trong truyn dn

    1. Cng sut pht.

    2. Di tn knh.

    3. T s S/N.

    4. Suy hao.

    5. Mo tr nhm.

    6. BER.

  • 31

    4.1 Cng sut pht

    Cng sut pht: Ph thuc hon ton vo my pht. Cng sut pht ln th khong cch truyn dn tt hn, xa

    hn. Tu thuc vo knh truyn dn m cng sut pht ca

    my pht c th thay i m bo vic truyn dn vkhng tc ng ln cc h thng xung quanh.

  • 32

    4.2. Di tn hay Bng thngA

    F

    Bng thng tuyt i rng ph (c o bng s chnh lch tn s cao nht v thp nht

    m knh h tr) Bng thng cng ln, tc truyn cng cao

    Bng thng hiu dng Bng thng Di tm tn s hp cha hu ht nng lng ca t/h

    500 2500

    Bandwidth = 2500 500 = 2000 Hz

  • 33

    4.3. T s tn hiu/ nhiu (S/N)

    T s tn hiu/nhiu (S/N): c trng cho mi trngtruyn dn.

    T s S/N cao tng ng vi knh truyn tt, nnh cao, khng b tc ng nhiu ca nhiu. Ngc linu t s S/N thp th knh truyn ny b tc ng rtnhiu ca nhiu.

    i vi knh truyn c t s S/N thp th bt buc phi sdng m ho, tri ph nhm chng nhiu.

  • 34

    4.4. Suy hao hay Suy gim tn hiu

    T/h nhn c khc vi t/h truyn i Analog suy gim cht lng t/h Digital li trn bit

    Nguyn nhn Suy yu v mo do suy yu trn ng truyn Mo do tr truyn Nhiu

  • 35

    suy gim tn hiu nh ngha (signal attenuation)

    Khi mt tn hiu lan truyn qua mt mi trng truyn, cng (bin ) ca tn hiu b suy gim (theo khong cch)

    Ty thuc vo mi trng truyn dn i vi mi trng v tuyn, suy gim cng t/h l mt hm phc

    tp theo khong cch v thnh phn kh quyn Cng t/h nhn phi

    mnh thit b nhn nhn bit c cao so vi nhiu t/h khng b li Suy yu l mt hm tng theo tn s K thut cn bng suy yu trn di tn s Dng b khuych ai (khuych i tn s cao nhiu hn)

    o bng n v decibel (dB) Cng t/h suy gim theo hm logarit li/ hao ht ca cc tng ni tip c th c tnh bng php

    ton n gin (+/-)

  • 36

    suy gim tn hiu o bng n v decibel (dB) Cng t/h suy gim theo hm logarit li/ hao ht ca cc tng ni tip c th c tnh

    bng php ton n gin (+/-) Cng thc Attenuation = 10log10(P1/P2) (dB)

    P1: cng sut ca tn hiu nhn (W) P2: cng sut ca tn hiu truyn (W)

    Decibel (dB) l gi tr sai bit tng i Cng sut suy gim hao ht l 3dB Cng sut tng gp i li l 3dB

  • 37

    4.5. Tr lan truyn tn hiu Mo tr truyn

    Ch xy ra trong mi trng truyn dn hu tuyn Vn tc lan truyn thay i theo tn s

    Vn tc cao nht gn tn s trung tm Cc thnh phn tn s khc nhau s n ch cc thi im khc

    nhau Cng thc

    Transmission propagation delayTp = S/V

    S : khong cch vt l (meter) V : vn tc lan truyn tn hiu trn mi trng truyn, vd: vi

    sng in t: v = 2 x 106 (m/s)

    Round trip delay Tx = N/R

    N : khi lng d liu truyn (bit) R : tc truyn bit trn ng truyn.

  • 38

    Tham s cht lng c bn ca HTTTS

    Yu cu ca h thng thng tin s: tin cy cao v tc truyn nhanh.

    i vi thng tin: Tham s chnh nh gi cht lng hthng nh gi qua t l li bit (BER: Bit Error Ratio).

    BER: L t l gia s bit nhn b li v tng s bit truyn trong khong thi gian quan st.

    Khi khong thi gian quan st tin n v hn th t l libit tin ti xc sut li bit.

    Khi BER > 10-3 th h thng truyn dn c xem l ginon.

  • 39

    5. Mi trng truyn dn Hu tuyn (guided media wire)

    Cp ng Cp quang

    V tuyn (unguided media wireless) V tinh H thng sng radio: troposcatter, microwave, ...

    c tnh v cht lng c xc nh bi mi trng v tn hiu i vi hu tuyn, mi trng nh hng ln hn i vi v tuyn, bng thng to ra bi anten nh hng ln hn

    Yu t nh hng trong vic thit k: tc d liu v khong cch Bng thng

    Bng thng cao th tc d liu cao Suy yu truyn dn

    Nhiu (nhiu nhit, nhiu iu ch, nhiu xuyn knh, nhiu xung) S thit b nhn (receiver)

    Mi trng hu tuyn Cng nhiu thit b nhn, tn hiu truyn cng mau suy gim

  • 40

    Mi trng truyn dn

  • 41

    Mi trng truyn dn hu tuyn Cp xon i Cp ng trc Cp quang

    Frequency Range

    Typical Attenuation

    Typical Delay Repeater Spacing

    Twisted pair (with loading)

    0 to 3.5 kHz 0.2 dB/km @ 1 kHz

    50 s/km 2 km

    Twisted pairs (multi-pair cables)

    0 to 1 MHz 0.7 dB/km @ 1 kHz

    5 s/km 2 km

    Coaxial cable 0 to 500 MHz 7 dB/km @ 10 MHz

    4 s/km 1 to 9 km

    Optical fiber 186 to 370 THz 0.2 to 0.5 dB/km

    5 s/km 40 km

  • 42

    Cp ng: two-wire open line

    Single pair

    Flat ribon

    Terminating Connector

  • 43

    Cp ng: twisted-pair Tch ri Xon li vi nhau Thng c b li

    Insulatingouter cover

    Multi core

    Insulatingouter cover

    Protective screen (shield)

  • 44

    Cp ng: twisted-pair ng dng Mi trng truyn dn thng dng nht Mng in thoi

    Gia cc thu bao v hp cp (subscriber loop) Kt ni cc ta nh

    Tng i ni b (Private Branch eXchange PBX) Mng cc b (LAN)

    10Mbps hoc 100Mbps

    u nhc im R D dng lm ch Tc d liu thp Tm ngn

  • 45

    Cp ng: twisted-pairc tnh truyn dnAnalog

    Cn b khuch i mi 5km ti 6km suy gim t/h: ~1dB/km Chun trong T: = 6dB

    Digital Dng tn hiu tng t hoc tn hiu s Cn b lp (repeater) mi 2km hoc 3km

    Khong cch gii hnBng thng gii hn (1MHz)Tc d liu gii hn (100MHz)D b nhiu v tc ng ca mi trng ngoi

  • 46

    Cp ng: twisted-pair Khng v bc gip Unshielded Twisted Pair (UTP)

    Dy T bnh thng R nht D lp t D b nhiu trng in t bn ngoi

    V bc gip Shielded Twisted Pair (STP) V gip bn gip gim nhiu v tc ng bn ngoi t hn Kh lp t (cng, nng)

  • 47

    Cp ng: twisted-pair UTP Cat 3

    Ln n 16MHz c dng trong lin lc thoi hu ht cc

    vn phng Chiu di xon (twist length): 7.5cm ti 10cm

    UTP Cat 4 Ln n 20 MHz

    UTP Cat 5 Ln n 100MHz c dng ph bin hin nay trong cc vn

    phng Chiu di xon: 0.6cm n 0.85cm Thch hp cho tc truyn ln n 100.106

    bits/second

    STP Cat 3: thch hp cho tc truyn ln n10.106 bits/second

  • 48

    Cp ng: twisted-pair

  • 49

    Cp ng: Unshielded Twisted-Pair

  • 50

    Cp ng: Shielded Twisted-Pair

  • 51

    Cp ng: Coaxial ng dng

    Mi trng truyn linh hot nht Cp truyn hnh Truyn dn T khong cch xa

    FDM C th mang ng thi 10.000 cuc gi S b thay th bi cp quang

    Kt ni cc thit b khong cch gn Mng cc b

    c tnh truyn dn Hiu ng b mt (skin effect) Analog

    Cn b khuych i mi vi km Khong cch cng ngn nu tn s cng cao Ln n 500MHz

    Digital Cn b lp (repeater) mi km

  • 52

    Cp ng: Coaxial

  • 53

    Cp ng: coaxial

    Insulatingouter cover

    Braided outerconductor

    Dielectricinsulatingmaterial

    Centerconductor

    Insulatingouter cover

    Braided outerconductor

    Dielectricinsulatingmaterial

    Centerconductor

  • 54

    Cp ng: c im chung Xc sut bit li trn ng truyn (Bit Error Rate BER)

    vo khong 10-6. D b nh hng ca nhiu (crosstalk, thermal,...) v mi

    trng xung quanh. Tc truyn thng tin thay i ty theo phm vi h

    thng c trin khai : LAN: tc 10Mbps ~ 100Mbps, khong cch khong vi

    trm mt (UTP: length < 100 m). WAN: tc truyn thp hn, t vi chc Kbps n vi

    Mbps. V d: T1 ~ 1,5Mbps, E1 ~ 2Mbps, ng T: 64Kbps

  • 55

    Cp quang

    Single core

    Multicore

    Plasticcoating

    Optical core Optical claddingSingle core

    Multicore

    Plasticcoating

    Optical core Optical cladding

  • 56

    Cp quang

  • 57

    Cp quang: li ch v ng dng Li ch

    Dung lng cao Tc d liu hng trm Gbps (so vi 100Mbps trn 1km coaxial

    cable v thp hn ca twisted-pair cable) Kch thc v trng lng nh suy hao ca tn hiu trn ng truyn thp. Cch ly trng in t (t b nh hng ca nhiu v mi trng xung

    quanh) Khong cch gia cc b lp xa T l bit li trn ng truyn vo khong 10-9 10-12

    ng dng Phm vi trin khai rt a dng: LAN (vi km), WAN (hng chc km). Mi trng truyn thch hp trin khai cc ng dng mng s a

    dch v tch hp bng rng (Broadband Integrated Services Digital Networks)

    ng trung k khong cch xa Trung k th Trung k tng i nng thn

    h b

  • 58

    Cp quang: c tnh truyn dn Sng lan truyn c hng 1014 n 1015 Hz Mt phn ph hng ngoi v ph nhn thy c

    Light Emitting Diode (LED) R Tm nhit hot ng rng Tui th cao

    Injection Laser Diode (ILD) Hiu qu hn Tc d liu cao hn

    Wavelength Division Multiplexing

  • 59

    Cp quang: c tnh truyn dn Sng lan truyn c hng 1014

    n 1015 Hz Mt phn ph hng ngoi v

    ph nhn thy c Light Emitting Diode (LED)

    R Tm nhit hot ng rng Tui th cao

    Injection Laser Diode (ILD) Hiu qu hn Tc d liu cao hn

    Wavelength Division Multiplexing

    Ngunsng

    LED/ILD

    LED/ILD

    ILD

    Bngthng

    20MHz/km

    1GHz/km

    Ln n1000GHz/km

    ng dng LAN, computer data links

    Mod length phone lines

    Long haul telecom. lines

    ngknh li(m)

    > 80 50 60 1.5 5

    suygim t/h(dB/km)

    0.5 2.0

    0.5 2.0 0.15

  • 60

    Cp quang: ch truyn

    multimode: several paths/time delays

    narrow: 1 wavelength no time delays

  • 61

    Cp quang: ch truynStep-index multimode

    Graded-index multimode Single-mode

    Ngun sng LED/ILD LED/ILD ILD

    Bng thng Rng (ln n200MHz/km)

    Rt rng (200MHz-3GHz/km)

    Cc rng (3GHz-50GHz/km)

    Ghp ni kh kh kh

    ng dng Truyn d liumy tnh

    ng in thoi (khongcch trung bnh)

    Vin thng ng di

    Gi thnh R nht Trung bnh t nht

    ng knh li(m)

    50-125 50-125 2-8

    ng knh v(m)

    125-440 125-440 15-60

    suy gim(db/km)

    10-50 7-15 0.2-2

  • 62

    Cp quangOptical Dielectric SLT Cable, 72-Fiber, Composite (24 SM/48MM)

  • 63

    Truyn dn v tuyn Truyn v nhn thng qua anten C hng

    Chm nh hng (focused beam) i hi s canh chnh hng cn

    thn V hng

    Tn hiu lan truyn theo mi hng C th c nhn bi nhiu anten

    Tm tn s 2GHz n 40GHz

    Sng viba (microwave) nh hng cao im-im V tinh

    30MHz n 1GHz V hng radio

    3 x 1011 n 2 x 1014 Hng ngoi Cc b

    Khc phc nhng kh khn v al khi trin khai h thng

    T l bit li trn ng truyn(BER) thay i ty theo h thngc trin khai. V d: BER ca vtinh ~ 10-10

    Tc truyn thng tin t cthay i, t vi Mbps n hng trmMbps

    Phm vi trin khai a dng: LAN (vi km), WAN (hng chc km)

    Chi ph trin khai h thng ban u rt cao

  • 64

    V tuyn: cc bng tn truyn dn

  • 65

    V tuyn: sng viba mt t Cho parabol (thng 10 inch) Chm sng nh hng theo ng ngm (line of sight) Khong cch max gia cc anten

    h: chiu cao ca anten k: hng s hiu chnh gp khc ca sng (k=4/3) V d: thp anten cao 100m cch xa 82km Chui thp anten: im-im

    suy gim t/h d: khong cch : chiu di sng suy gim t l thun bnh phng khong cch cn

    amp/repeater mi 10-100km suy gim thay i theo mi trng (cng tng khi c ma)

    Vin thng khong cch xa Thay th cho cp ng trc (cn t b amp/repeater, nhng phi nm

    trn ng thng) Tn s cng cao th tc d liu cng cao

    khd 14.7=

    ( ) dBL d 24log10 =

  • 66

    V tuyn: sng v tin...