Mạng HFC Va Công nghệ Cable Modem

2 Page 1

..................................................................................................................... 1

.............................................................................. 3

PH L NH .................................................................................................. 4

THUT NG VIT TT ............................................................................................. 6

............................................................................................................... 9

1 NG HFC( Hybrid Fiber Coaxial) ........................................................ 11

1.1. Tng quan v m ng HFC ........................................................................................ 11

1 2 ..................................................................................... 19

1 2 1 .................................................................................. 19

1 2 2 .................................................................... 21

1.2.2.1. B khu i hai chiu .................................................................................... 21

1 2 2 2 p q p ng trc trong m ng ............................................................ 22

1.2.2.3.Cu r (Tap) ....................................................................................................... 23

1.2.2.4.Node quang ........................................................................................................ 24

1.2.2.5. Thi t b k t cui truy STB (Set-Top-Box) ........................................... 24

1 2 2 6 p ( ) ....................................................................... 25

1.2.2.7. H thng k t n p CMTS .............................................................. 26

1.2.2.8. H thng IP Phone ............................................................................................ 27

1.2.2.9. H thng thi t b c d ch v ................................................. 27

1.3. IEEE 802.14 ........................................................................................................... 27

1 .............................................................................................. 28

1 s ......................................................................................................... 29

1 6 .............................................................................. 30

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1 7 ng HFC ............................................................................... 31

1 7 1 ............................................................................................................. 31

1 7 2 t trong m ng HFC ...................................................................... 32

2 E ODE .................................................................................... 36

2 1 m v Cable Modem ................................................................... 36

2.2. L ch s i c Cable Modem ........................................ 36

2.3. C a Cable Modem ..................................................................................... 37

2 3 1 c a Cable Modem ......................................................................... 37

2.3.1.1. Tuner ................................................................................................................ 38

2.3.1.2. Demodulator ..................................................................................................... 39

2.3.1.3. Media Access Control (MAC) ........................................................................... 40

2.3.1.4. Microcessor....................................................................................................... 41

2 k p p cable modem ............................................................... 41

2.5. Ph cable modem .................................................................................................... 42

2 6 x c a cable modem ........................................................................................ 43

2 7 p ............................................................. 44

2 7 1 p CM ................................................................................................ 45

2.7.2. H thng k t cu p CMTS ................................................................ 45

2.7.3. Mt s server trong m p .................................................................. 46

2 s ( )................................ 46

U THAM KH O.............................................................................................. 48

2 Page 3

H tn thnh vin

Ni dung cng vic

Ph Q ( ng)

- u - q

Nguy

- u - Truyn d ng HFC

Nguyn Q

- u - m cu t o - m

- u - Cable Modem

Nguy ng

- u - ng HFC

- u - IEEE 802.14

Tr nh

- u - s

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PH L NH

1 1 n m ng HFC ........................................................................... 11

1 2 h thng headend ................................................................................. 12

1 3 k ............................................................................. 13

1 .................................................................................... 14

1 p ...................................................................... 15

1 6 p ........................................................................ 17

1 7 truyn d ng HFC ................................................................... 19

1 ............................................................. 19

1 khu i 2 chiu .................................................................................... 21

1 1 ng truyn p n d n b p q p

ng trc........................................................................................................................ 22

1 11 p q ....................................................................................... 22

1 12 p ng trc .................................................................................. 23

1 13 u truy p f 1 ....................................... 23

1 1 u r ( p) s ......................................................... 24

1 1 quang .................................................................................................. 24

1 16 Top Box trong truy p ......................................................... 25

1 17 p .................................................................................................. 26

1 1 k O ........................................................ 29

2 1 .................................................................................. 36

2 2 c ......................................................................... 37

2 3 E -CABLE MODEM .............................................................. 38

2 u ch QAM ................................................................................. 40

2 Page 5

2 khi b chuy i D/A ....................................................................... 40

2 6 k p p c a Cable Modem ............................................... 42

2 7 RF c a Cable Modem .............................................................................. 43

2 x ph Headend/station........................................................................... 43

2 p n c a h thng Cable Modem ................................................... 44

2 1 thng chu ................................................. 46

2 Page 6

THUT NG VIT TT

T vit tt gha ting anh gha ting vit

CM Cable Modem p

TV Television Truy

RF Radio Frequency Tn s n

MAC Medium Access Control u khi n truy nhp

ng

QAM Quadrature Amplitude

Modulation u ch c p

CATV Communitty Attenna

Television

Truy q ng

ng

HFC Hybrid Fiber Coaxial M p q p ng

trc

CMTS Cable Modem Terminater

System H thng k t cu p

FN Fiber Node q

LAN Local Area Network M c b

WAN Wide Area Network M ng di n rng

SONET Synchronous Optical

Network Chu n truyn d ng b

DHCP Dynamic Host Configuration

Protocol Giao thc c ng

2 Page 7

FDM Frequency Division

Multiplexing p p n s

VOD Video On Demand Truy u

HDTV High Density Television Truy p i cao

HFC Hybrid Fiber Coaxial

M p q p ng

trc

HFPC Hybrid Fiber Passive Coaxial M p q p ng

trc th ng

SDH Synchronous Digital

Hierarchy p s ng b

STB Set Top Box Thi t b k t cui truy

IF Intermediate Frequency Trung tn

HDTV High Density Television Truy p i cao

IP Internet Protocol

ISP Internet Service Provider p

IEEE Institute of Electrical and

Electronic Engineers

Vi u k thu n

n t

HE Headend x

ATM Asynchronous Transfer Mode Ch truyn kh ng b

DLC Digitar Loop Carrier p s

QPSK Quadrature Phase Shift iu ch pha c p

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MUX Multiplex p ( )

PC Personal Computer

CPU Central Processing Unit x

NTSC National Television System

Committee

PCI Peripheral Component

Interconnect

( )

QoS Quality of Service cht

ng d ch v

PHY Physical

DSL Digital Subscriber Line K s

DSLAM Digital Subscriber Line

Access Multiplexer

Thi t b cung cp d ch v

D p ng

IEEE Institute of Electrical and

Electronic Engineers

Vi u k thu n

n t

2 Page 9

ng cable TV truyn thng s d p ng trc, t n

m c a mt m p ng tr n nhi k i

ng truyn: c kho ng 1km l i cn m k n u m

bao x k 3 k n kho 3 k ng

truyn.

Vi c cn s dng nhi k i d sau:

+ V li m ng: n u m k i g s c

tt c u b ng.

+ Ch ng truyn b ng: sau mi l c khuy i,

u b nhi v xa, ch ng

truyn s b ng.

M ng HFC khc ph p q

n mt lo p p i quang. T p p u quang s

c chuy p ng trc s c s d k t n

m c

+ s ng d ch v.

+ H n ch s c g

+ Chia mt m ng trc l ng trc nh, mi m ng

xu p m m phn ph q ng nh

c lp v c s c thng.

V truy p u tuy s dng hi i Vi

HFC (Hybrid Fiber Coaxial Cable) - p p q

p ng trc.

M ng truy p n th s d t b

p ng tr khuy

hi k p c v p k p c nhu c i xem c v

ch ch v.

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ng truy p s d HFC, vi phn truyn

d n s d p q m c s d

tn c p q suy hao thp khc phc nh m c a

m ng CATV truyn thng. M ng HFC- k p mt lo ch

v OD c bi Internet.

Kh a Truy p p u tuy

thng truy u truy c truyn d n b p n tng h

truyn s li ng truy p ( )

ngh Cable Modem.

x

2

h ng ng id i a ia : s k

k p

s s EEE

2 1

h ng 2 a d m q

Cable Modem, l ch s i c

s s m v, ch a nh p n c

p s p n nh ng chu n hi c

s d DO D EEE 2 1

ng r s cung cp c m

v HFC & Cable Modem. M gng rt nhiu song do th

n, ni dung c k k i nh ng thi s

t mong nh c nh k p ti p tc

chnh s a.

.

H N

hm 5 5- T T2

Kh a T T

T ng i hc in Lc

2 Page 11

NG HFC( Hybrid Fiber Coaxial)

1.1. Tng quan v m ng HFC

HFC (Hybrid Fiber Coaxial) mt m ng gi a p quang p ng

trc t o ra mt m ng rng. s d ng th p q p ng trc

truyn p p u. Vi c truy u t q

p q q p ng trc.

HFC c s p 1 ki

s

nh Kin t c c bn m ng HFC

M ng p quang m rng t headend ch (master headend) n headend

(regional headend), hubsite c a m ng cn sau chuy n i

q n (fiber optic node) phc v t 500 2 bao m i

Master headend ng antenparabol v tinh thu hi u video trong

k gian lung IP. Mt s masterheadend bao gm thi t b

n tho i cung cp d ch v vin n cng ng. Mt regional headend

thu hi u video t master headend k c a ph , k

dc, k cng khi c p p hoc qu ng

h thng h

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nh 1.2: S h thng headend

Headend thu nhn hi u t nhiu ngun k nhau ( hi u qu ng

v tinh, hi u s n xut ). Sau khi qua c x u ch ,

p k , trn... hi u c ra m ng truyn d n p phi n

bao.

Fiber optic node mt b thu p quang rng kh chuy n i

hi u u ch quang chiu xung n t headend ra hi u n gi n

bao, chuy i hi u n n t bao ra hi u quang

cho chiu c l i. hi u n chiu xung gi n bao hi u u ch

RF nm trong d i tn t 50 MHz 1 MHz. p q p n

headend hoc hub theo point-to-point hoc star topology hoc ring topology. Fiber

p s p s g n

headend. M u theo chi c l u ch RF nm trong d i tn t

z 2 z nh ng khu v k z 6 z

Phn p ng trc c a m ng k t ni t 25 2 bao ( ng 500

bao) theo cu d ng b khu ch i RF c s dng

khu ch i hi u, l i suy hao do p suy hao k t

chia p hoc r p p ng trc trung k c k t ni n optical node

d ng c a coaxial backbone p phi p k t ni nh p trung k

t i ngun AC t 60V n 90V. Ngun AC cung cp cho b khu ch

T p trung k , p p phi nh c k t ni n mt cng c a b

khu i trung k t n AC xu t.

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Cng c a b khu i trung k t n AC xu

t. Khi cn thi k khu p

phi nh s khu gi s t c u TV m

chp nh p p c m r nh m r

d r n l i ngun

AC tr k t b n tho i cn thi n d p p t

h thng ngu p ng tr k t cui r m r

bi ng s d u ni lo D n b o

v h thng t nh p t k m q

ng h p q u TV k t n ng

nh c a tt c t xu.

M ng HFC bao gm 3 m (s ) ng truyn d n (Transport

segment), m p p (D s s ) ng truy nhp ( Acess

segment).

nh S in t c m ng

ng t u n d n

ng truyn d

p u tuy ng truyn d p q t hay

mt s p q k t ni gi E s p s p, trong mt s

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ng h p k cp l k t gi s p v

th cp t q c li k t v E s

ng truyn d s l a ch n c a phn l

p d ch v qua m p gii bi nh m ni bt c a

h thng...

M ng truyn d n bao gm h th p q s p, nhi m

v c n d u t h k x s p

/p q / q n ti p u

quang t k

nh ng t u n d n

u t trung q chuy q u quang

s c truyn d q p s i quang t

th t tr p i n p u cho mt ph m vi ln

(gi p ) ch chia quang

hi u quang t q thu a h thng

u t n t i t c thi t k theo c

m ( ) s ( ) u sau n q c chuy n

i t q s s c truyn d p ng tr truyn d n

2 Page 15

n tng h q p ng trc nh khu

hi chia cao tn.

ng h n hi

M p p u bao gm h th p q c Hub th cp

q u quang t s c chuy n

t q truy c l ng h p m ng 2

chi u t m ng truy nhp s c thu t q

q truy n Hub v headend.

ng t u nh :

M ng truy nhp bao gm h th p ng tr t b p

t m v truyn t u cao t q t

b k p c v c a m ng con truy cp t

kho ng 300m.

M ng truy nhp truy u t node quang t ng

2 k

Mng truy nhp kiu HFPC (Hybrid Fiber Pasive Coaxal):

ng lai gi p q p ng tr

thi t b th k k t thi t b

m ng trc.

nh 5 u t c m ng t u nh

2 Page 16

c im ca m ng t u nh

+ p x ng theo m ng 1 chiu hay 2 chiu.

+ S d q s t ln.

+ M ng quang chi m t tr ng l m ng tng th .

+ M ng trc ch n tr p

v t b chia th ng.

+ Kh p c v t 400-600 t / q

u im:

+ Ch u t k s d khu i.

+ D k s d khu i cao t p

t, v

+ t b th k u 2 chi n

nh m ng v n cao khi tri n khai m ng 2 chiu.

+ S / q k p tt d ch

v 2 chiu vi t cao.

+ Gi p p ngu n, b ng, thay th t

b c.

h c im:

+ Kh p c a 1 node quang nh k s dng khu ch

i.

+ Y u node quang s dng ph s t ln, ch ng cao,

nh.

Mng truy nhp kiu HFC (Hybrid Fiber Coaxial)

m ng lai gi a p quang p ng trc trong s dng thi t

b c c ( b khu ch i cao tn ) m ng ng trc.

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nh u t c m ng t u nh

c im ca m ng t u nh HFC:

+ p x ng theo m ng 1 chiu hay 2 chiu.

+ M ng trc chi m t tr ng l m ng tng th .

+ M ng tr 3 p:

- Cp tr p ng trc tr k i

trc, b ng trc.

- Cp tr p ng tr khu i

- Cp m p ng tr

+ Kh p c v t 1500-2 / q

2 Page 18

u im

+ Ph m vi bao ph c a 1 node quang ln nh k ng trc

bi s d k i cao tn.

+ p u thp nh s d q

h c im:

+ Ch u thp k u m ng HFPC.

+ n l i khi tri k ng 2 chiu.

+ Y u cht ch v ngun cp u, n m cp ngu

m n tuy p s u.

+ ng phc t p.

S nh v

q k

q s x k q

p

k k 2

2 Page 19

2 T u n d n t n m ng

1.2.1 T u n d n t n m ng

Truyn d n trong m ng H c ch 1 7

nh 7 S truyn d n t n m ng HFC

nh 8 ng d h ad nd n c c thu a

2 Page 20

s t k p

v tinh, ngun qu s i i

p k q s ( ) u

c truyn t s p. Mi Hub

s p cung cp u ho kho 1 k ng 4 hoc 5 Hub th

cp i h t, mi Hub th cp c s d p p i ph

hi hoc s p k i m m vi p k

Video t s p cp k u chiu ti hoc chiu

xung t i tin tc t / ff i dung video, tho

d li u chiu lui hoc chi i tin tc t n

/ ff u khi n STB, d li i.

k s c c chia s s d

m ng backbone. M k x ng theo ki s d

ngh SONET/SDH hoc mt s c quyn.

m c O E / D p t d li u t t

OC-1(51,84Mb/s)/STM-1 (155,52 Mb/s) t gp n t

Trong m O E / D c s u ch p

k D c truyn k OC-12/STM-4 (622 Mb/s) ti

OC-4/STM-16 (2448 Mb/s). s dng k thu p k k D

r n s d p k k D c hi n cp p k

th th c hi ch v i qua m ng

O E / D n m D q x nh

bi s p q nh vi

kho 1 c c ln vi kho 2

p s Op s ( Os) p p p p gi

ch v b p q p ng tr p p

th truy v n s dng r u

ch k p p p s d truyn

d k q k k chi m

6 z k t tn s s ( k 2

2 Page 21

n s 2 z) k m gi k n k .

k V s t o ra m n video hi u qu

MPEG-2 hoc MPEG- k Q (Q p )

1.2.2 Thit t u n d n t ng m ng

1.2.2.1. B khuch i hai chiu

Trong phn m ng p ng trc, b khu ch i hai chiu c s dng bao

gm hai lo i:

- B khu p p i ( khu 2 u

p k )

- B khu rng Line Extender Amplifier mt h thng

HFC hi n 6 b khu i cho tng khu i RF sau mi

node.

s khu ch t u ch p nh k

nhi s p ng tn s.

nh : B khuch i 2 chiu

2 Page 22

1.2.2 2 quang v c ng trc trong m ng

nh 0: Kin t c m ng truyn h nh c truyn d n bng c quang v c

ng trc

quang

M p q a t 12 n 14 s q k mi lo p

Lo i s p c s dng s - s k ng 0,4

dB/km s ng l=1310 nm hoc suy hao 0,25 dB/km l=1550 nm(mc

s nh trong d i nhi c lp vi d i tn s n).

nh : c i c quang

2 Page 23

ng t c

n xu p n q k n nht (t 7 n

1,09 cm) ch ng tt nht, suy hao 45 dB/km 750 MHz hoc 9dB/km 40 Mhz.

n cui g s k ng 25 cm k , suy

hao kho ng 114 dB/km 40 MHz (m s p thu u

c p)

nh 2 c i c ng trc

1.2.2.3.Cu r (Tap)

Mi cu r 2 p n t ch k p chia

s s s ng cng c a cu r (

th 2 ) k p m v ng 1 s u

x nh.

nh : B chia tn hiu truyn h nh c Pacific 1 v 4 ra

2 Page 24

( p) 1 12:

H nh 1.14: Cu r Ta v t u n d n

1.2.2.4. Node quang

phn t nm ng ranh gii gi a p quang p ng trc, nhi m

v b n chuy n i hi u n cho ng xung ( c l i ) khu

p phi m ng p ng trc vi 3 hoc 4 u ra mi node.

nh 5: Node quang

1.2.2.5. Thit b kt cui truyn h nh STB (Set-Top-Box)

Thi t b k t cu u truy i hai lo s.

k

k p q n m q

p p d ch v x p t s d ch v c bi k c thanh

s d n tho ho

m n 1996 STB s c gii thi u vi mt s ch n:

2 Page 25

+ D k s d ch v t trong d i tn ng xung .

+ Gi i u ch k s thu c. u ch k s p

+ Gi i / k ch n.

+ Qu n hi u bao t Headend.

Cung cp giao di i s dng. G i ti c

tri n khai b / s s kp

p p p p bao s dng d ch v truyn

d ch v p p s

i ti n ho t c RGW.

p giao thc IP n thi t b IP voice, IP

videophone.

Truyn t i, x u truy p i cao HDTV.

nh : Set Top Box trong truyn h nh c

1.2.2 d m c a d m

t b n p p p

( ng ) p n v i

p

+ Lo i khi c k t ni v q k t n E (

th k t n E p

a mt b nh tuy n ) hoc giao di n k t ni USB.

2 Page 26

+ Lo i card cm n ng c i

nht song ch s ph i

s thi t k k x ay.

+ Lo i th ba c p p i

ti

nh 7 d m c

1.2.2.7. H thng kt ni m d m c CMTS

H th m trong Headend, thuc v k a m ng so vi modem

p t b k t ni c ng t p

p n gi p ng

Internet IP.

+ u ch t DSLAM trong h thng DSL.

+ m k

nh tuy k t n ng Internet.

+ Mi CMTS cha mt hoc nhi ( )

CMLC chuy s li ng xu ( n

) s q t k t

k k x p u truyn

c l i v t s server trong m ng modem

p D (D ) x nh bi RF2181.

p a ch IP theo nhu c p t b

s D ( f D ) x nh b 6

nhi m v s ki th

2 Page 27

ch TFP ( Trivial File Protoco ) x nh b 13 k

t i v f p ch v .

1.2.2.8. H thng IP Phone

thng s dng giao th truy u tho i qua m ng vin

c chu n cho lp chuy n m ng

LAN, WAN,... M ng IP m ng s li c lp vi lp v p c h

thng truyn t i tho n trong vi c t o thun l i

HFC th c hi n mt xa l c s truyn m i lo u : voice, data,

video. H th s dng thi t b k t cu n tho i IP phone hoc

n tho i truyn thng POTS phone k t ni vi m p / t STB s.

p t b k k k t n n mt t s h u

k t n n cng Ethernet chu n trong m p / t STB s / mt PC trong

p t thi t b a ch a

k t ni m O p n m p / s ph i

giao di n m p p / s cung cp

ch

1.2.2.9. H thng thit b thu a v tnh c c d ch v

m ct y u nh i v p d ch v truy ti

th qu p c c ch v. M p p p p

u qu nh s d u ( ch nh

p d ch v p p c gi xem ).

H thng qu truy nhp c c g thng truy

nhp u ki n.

1.3. IEEE 802.14

EEE 2 1 11 1 chu n

p v ( Y ) p u khi n truy nhp p n (MAC layer)

cho thng HFC.

2 Page 28

MAC layer:

H tr ch v ss -oriented

H tr QoS.

H tr CBR, VBR, ABR.

H tr ch v unicast, multicast, broadcast.

PHY layer:

m thi t k tham chi u.

H tr sub-sp ( z z ps ) -sp ( z12

z ps ) -sp ( z1 z ps )

S dng l i tn s chi

L a ch u ch QAM 64 cho chiu xung.

QAM-64 vi 6 bit/Hz t o ra 30 Mbps trong 6 MHz.

u ch QPS c ch n cho chi ch ng nhiu ln.

k k u xung.

n k thu u ch s dng 5,12 Msymbols/second cho chiu xu

mt k thu u ch s dng 1,28 Msymbols/second cho chi

Tc bit c a k thut u ch

QPSK: 2 bits/symbol x 5,12 Msymbols/second = 10,24 Mbps.

16 QAM: 4 bits/symbol x 5,12 Msymbols/second = 20,48 Mbps.



QPSK: 2 bits/symbol x 1,28 Msymbols/second = 2,56 Mbps.

1.4. Kh n ng ng thng

Ph k u xu z7 z

Ph k z 2 z

Ph z7 z 33 k 6 z

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Ph z 2 z 2 k 1 z

Chiu xung:

Q 33 k D x 1 2 ps/k = 337 ps

16 Q 33 k D x 2 ps/k = 1 13 ps

6 Q 33 k D x 6 ps/k = 13 1 ps

Chiu n

Q 2 k D x 2 6 ps/k = 1 ps

5 t t n

Cu POST HFC c ch ra trong 1.15. Mt b chuy n m ch

hoc DLC (Digitar Loop Carrier: b cung cp s) t t i headend.

B u khi n headend nh k i t t t

q D c b chuy n m ti nh x

DLC k T1 truyn d ch tho i s c k t n n mt t

class 5 g x c g i.

c trang b a t n m ch

class 5, vi kh th c hi n:

nh 8: Headend vi c c h n ng OST v

Chuy n m ch ni h t.

c.

2 Page 30

R t ng truyn t i h p tr c ti p

ng truyn t t ki p p

cho k

c trang b u khi ch v

k t vi m ng internet. B u khi n headend s n giao

x

X ( t chuy n m ) ruy nhp ATM

k t n n d n b chuy n m ch ATM trong m

cng. B u khi p li u,

video ho ch v CBR. Di p

ANI.

u nh c im ca m ng

p q s s

p q s p k D c ln, suy hao

u rt thp nhi n t, ch c tt. V s i

q c s n xu hi s q p p n

n s THz (10145 - 1015 Hz). u

p ng m u d ng truy k t

p n truyn d k c.

u quang truyn s i quang hi n nay ch y u nm trong 2 ca s c

s q 131 1 2 a s s u rt nh 3

/k s 131 2 s 1 k i mt

s p ng trc lo i suy hao thp nh p i mt 43dB/km t i tn s 1 GHz.

u truy s p u quang, v k ng bi

n t t ng d n m b c ch ng

truy c ch t o t s s q t

li k c d c a s i cao.

k p ng h p s i quang b t.

2 Page 31

M m i thi k ch u truy

ng con truy nhp v n s d t b khu u

nh s p truy x k

m p , trc trc c a m ng truy p p n ln x y

khu t b p t b m r i

vi nh v , sa ch k th c hi n nhanh

n ch ng phc v k a m ng. V ng truy

nhp ng trc, khi cung cp d ch v 2 chi khu i c p phn t

khu nh c a m ng gi m. Do

v x gi ang chuy n dn sang s dng m ng truy nhp th ng.

1.7 An t n t ng mi t ng HFC

1.7 ii thiu

t ch rt quan tr ng k t k p n internet. Hu

h t tt c ng d u mt m

cp s

+ Nh i s dng d ch v (Users).

+ Nh q (Op s)

+ q p (Government agencies).

V p i s dng d ch v m b

n d li x k k t d ch v.

V p q n d li u,

c lp, gi i v k x

k n hoc la g m gi

khi d ch v k ng do s c p d ch

v/ q ng cn s gi p d n trong kinh doanh c a

h c a h i v k ng.

2 Page 32

V p q p h p l v

th q p p t, nh m b o l ch v, c

m o v s t.

Vi nh ng v t ra c v an

t b m nh ng ch ng dng

k u khi ch v m:

+ u khi n truy nhp.

+ X

+

+

1.7 2 An t n v m t trong m ng HFC

t trong m k nh ng m k t

n m- m truyn th ng h p c p ng, m

cp k t ni tr c ti p n mt m i t i h t, vi c nghe

trm th c hi k i v

k b s i s dng nh k

mt m p v k k p

v p ng HFC hai chi

n d n nhiu- n-m t- n-nhi t trung k .

c u cu an t n t i lp MAC:

C gng t ng truy nhp p

s s ng truy nhp p k

ch s

X ( ) p i t x p l i vi

m ng truy nhp. p x nh thi t b c

quyn phc v a nh i vi profile c a d ch v. S phc t p c a

q x c ph i thi n ra c

i xng.

2 Page 33

M ( p on): D li n

HFC ph mt.

B o v s p i (Replay protection): M ng truy nhp ph c b o v

n s p l

Qu k ( ) D i s dng

i vi bt k m

S thun l i v i s d u cu (E s )

ch k i s d u cui

th ng h tr i v thng.

su ( sp ) p i ho ng

k p c a d ch v (CoS-Class of Service) cung cp

i s dng.

Kh x t kh (Exp ) ng truy nhp p n

s s s dng world wide. Rt nhiu qu q nh

v s dng, nhp kh x t kh t

p ng tri q nh v xut kh p

kh u.

Truyn d li u tin c (D sp ) ng truy nhp

ph n chia s ph s i bit sao cho ti thi u m

rng l i bit c a m ng truyn d p k

k i bit b n do vi c m rng l n. H

thng ph k p ng b m c s k s n

truyn d n d li u.

( s s ) p p n chia

s ph k thu p n t c i tr

thu i m ng HFC.

p c s ( ) ng truy nhp

p n chia s ph c thi t k s k t lp

l o m ( k )

2 Page 34

Kh p ( p )

m ng truy nhp p n chia s ph p p p hay thay

m

M t m v gii m t m

M i m c th c hi n bng thu DE m s

d ( p k )

t s v v k thut m n bi s

M s dng ph c ch n.

M p c th p n cng hoc phn mm.

M p k u. D li s k

m k

Mt p tr

Gi i m p i gii h n khu i li.

M p i t ng b .

V c EEE 2 1 k t h p k thut m thng

MAC sao cho truy a mt tr x c. Th c

hi u n s bi a ch i nghe tr tht gi

p n d n chia s Q s

k ( x ) EEE 2 1 ngh s dng giao thc

k D ff -Hellman cho HFC.

Provisioning: Trong ch p p k

Chng th c ID c s c s d x

p p p c cn thi truy nhp

d ch v k D p n c bao (certification number or serial

number c a thi t b ) s d k t Diffie-Hellman.

k ( s ) u

ID duy nht c q p

p p ( q p s ) s x k t trao

th k ng th D c s d x

2 Page 35

th p p p k p nh D

k tht b i.

k t Diffie-Hellman: Thu p p i s

d k m

k k m i m

Thu D ff -Hellman d k t ri r c trong

s s i vi ng.

2 Page 36

2 A E ODE

2 Kh i nim v cng ngh Cable Modem

( ) truyn s li ng truyn

p ( ) ng lai gi p q p ng tr cung cp

u mt chiu.

M ng Internet c a truy p ng truy cp q

p

nh 2 h nh a d m

2.2. L ch s v mc ch a i ca cng ngh Cable Modem

p ln cung cp d ch v t 1

hi n nay Vi t Nam d ch v ng d k

D ch v cable- c cung cp m u megabit.

M g cung cp th c s s i ph thu p d ch

v i v k c x p p p O O

D a Cable Modem (CM) s thy

t d ch v rt tuy t, tuy n k s ng

d ch v s gi m xung.

n ch i s dng VN

ng gp ph i hi n nay khi s dng truyn s li u qua h th n tho i

h n v t . Vi chu mi V90, t t 6 ps

c s dng gi a thi t b c k

2 Page 37

cp d ch v tho p p p mt d p ng truyn

thng. M i c ng ngh ng nh p s

dng nh ng ng dng, d ch v m c tr c tuy n, xem phim

tr c tuy u k t ni m ng, truyn s li u t cao...Cable Modem cho

p p p Internet t mt phn nh c a thi

p s n thng dial- p

1) ng m i k t n n m

2) ch v " " k

h mun, khi h mu p p p

gi n tho i m c a h i vi cuc hi tho i bng

gi

2.3. C u t c ca Cable Modem

2 S c u t c ca Cable Modem

Cable Modem gm lo i lp p ng h p

p trong hp thu Set- p i ph i

t b p c chu u khi n khi k t ni Internet. Th c t k

th p ng Digital Cable, hp thu set- p k

k t ni th q ng k t n i s d

nhp Internet hay k

D lo s c t d

sau :

nh 2 2 S c u t c a d m

2 Page 38

Tuner - B u ch u.

Demodulator - B gi u d ng s.

Modulator - B gi u t dng s sang dng tu n t .

Media Access Control(MAC) - Thit b u khin truy nhp

Microprocessor - B x l

2.3.1.1. Tuner

Tuner-B u ch phn ni Modem Cable v p

hi u hoc vi b p k li u Internet ra kh k

ng. T li c Tuner ti p nh i d u s

s n t D p

t thi t b D p x p p s dng m n tn s (trong kho ng

42- z) D w s k ( k ng 5-42

MHz) cho Upstream.

p n c a b p s c thi t

k c s d ng dng trong k t qu c a vi c

p mt b l p

nh 2 h nh T ER-CABLE MODEM

2 Page 39

2.3.1.2. Demodulator

p c s d gi u ch

q ng trong vi c gi c chuy i t d

sang s.

D QAM (Quadrature Amplitude

Modulation) s u tun t g m c s

p i chuy s gi x i A/D Converter

(Analog to Digital Converter). A/D Converter nh u bi i theo

p i s 1

B sa li (Error Correction Module) s c ki n

s s i d li u chu n do v x y ra khi truyn d li

c ki k c phc. Trong hu h ng h p li u hay

w k f E t thi t b ng b E c s d

chc chn rng m i d li m b o truy

Ch th c p s

B nh p thng tin a li:

B nhp sa l (E ) p m

v ki s s d so

s i d li u chu ng v x y ra khi truyn d li u,

n s c s ngay lp t c khc phc.

B iu ch in cu h ng QA

B u ch c p Q (Q p )

n vi nhi m v truyn t u ch

c li u b i c

p s Q t d s t d s

Cosine v p o tn s chuy c giao gi a

s s p p n d li ng th k X x t chu

k s s

2 Page 40

nh 2 h nh iu ch QAM

B chuyn i D/A ( Digital to Analog Convenrter)

Chuy i s s y m c bi u di i

d s ( ) n th ho n t l

v s p p p c s d chuy D/ p

p p n tr p p p n tr

khi c a mt chuy i D/A:

nh 2 5 S khi b chuyn i D/A

2.3.1.3. Media Access Control (MAC)

MAC- u khi n truy nhp ng con giao thc truyn

d li u, mt phn c a t k t d li O p

a ch u khi n truy nhp k p p m cui hoc

c v t m ng.

2 Page 41

t t a vi giao th p

(multiple access protocol), do tng con MAC cung cp. Vi p p u tr m

k t ni t ng v

i vi Cable Modem p p ps

D w s th c ch n gi a phn c p n mm c

thc m k M i thi t b m i vi

p c t p u so v ( )

a MAC s do q nh.

hi ng s d a ch v

t b m ng, p t b v s d ng m ng.

2.3.1.4. Microcessor

ss t b vi x k t h p a mt b x

( ) t m p duy nht , hoc m p t

thi t b lp x nh t s n.

i vi Cable Modem, nhi m v c a b x p thu c Cable

c thi t k vi m s d n hay ch cho m k t

ni Internet ng. ng h p p trong PC, b x p

s t c a MAC.

2.4. h nh in t c h n p cable modem

EEE 2 1 x u khi n

headend. Ki t kh u tng c x nh ki

p p ng ki t d x

thi t b .

k p p / 3 1

g

+ ( )

+ Lp v (p s ( Y) )

+ Lp MAC (MAC layer).

2 Page 42

nh 2 h nh in t c h n p ca Cable Modem

U EEE 2 1 p i

chu p v

+ k

+ k u xung.

+ S hi t k thut.

2.5. Ph cable modem

Ph tn s c a chi u xu k

MHZ t Z Z k u xung,

bao g u ch Z Z n

Z k s chi k rng t 1 Z n 6

Z k s trong tm t 1 6 ps n 10 Mbps khi s

dng k thu u ch Q k c thi t k truy

u khi li n headend. Mt s ng l k u xung

nm trong n 300 MHZ gi Z 7 Z k c

p q li c t n tt c tr m thu.

2 Page 43

nh 2 7 h RF ca Cable Modem

2 nh ca cable modem

Truy c tt nh

3.3. Mt b (x t tr ) c k t n n tt c

k 6 Z u xung (t k 1 k ) a ph. Cable modem ph

kh u chnh b c b k n 6 M Z

nhn d li u t headend. T i k t cu p p k

p k k 1 k trong

2

nh 2 8 nh ph Headend/station

i tho i gi c khi t o khi mt modem lp t

ng b u l k u xu k n thi t b

c p ng l i bi vi c ch k p

truyn d li u c thu c k

2 Page 44

chiu xu k t v k i tho i gi a

s p qu n tr MAC ch m.

Kh s ng v th c

tham chi f q -agile cable modem.

2 7 c thnh hn ca h thng ca m d m

nh 2 c thnh hn ca h thng Cable Modem

Mt h thng CM bao g p n sau:

- B khu i 2 chiu.

- p q p ng trc trong m ng.

- Cu r (Tap).

- Node quang.

- Thi t b k t cui truy -STB.

- p( )

- H thng k t cu p

- Server trong m p

- H thng IP phone.

- H thng qu c d ch v.

2 Page 45

p k 2 p q p

1 p s p p

k p s p

2.7.1 d m c CM

thi t b n p p p n m

( ) p n v 3 i

p

+ Lo i khi c t n q k t n E (

nhi k t n E p

ch a b nh tuy n) hoc giao di n k t ni USB.

+ Lo i card c ng c

nht song ch s ph s

thi t k k x

+ Lo i th ba c p p i ti n

2.7.2. H thng kt cui m d m c CMTS

H th m trong Headend, thuc v p k a m ng so vi

p t b k t cu p

Headend c p n gi

p ng Interrnet IP.

+ u ch t DSLAM trong h thng DSL.

+ m k

nh tuy k t n ng Internet.

+ Mi CMTS cha mt hoc nhi p ( )

CMLC chuy s li ng xu (

) s k k x

p u truy c l i v ng

2 Page 46

2.7.3. Mt s server trong m ng m d m c

D x nh bi RF 21 1 p a ch

IP theo nhu c p t b s

D x nh b 6 m v i gian

s ki thng.

x nh bi RFC 1350 k i v f u

p ch v .

2 8 c chu n c dng t ng cng ngh a d m

nh 2 a h thng chu n a d m in h nh

p h s dng nhi o th c quy k

k s d p a nhiu

k t h th 1 7 3 n ni tr

EEE 2 1 D /D i di i di n cho Bc M vi

2 Page 47

b giao th DO n nay, nh ng chu ng c i ti n

l s c th p

+ DOCSIS g 3 1 DO 1 1 DO 2 DO c

p n b s c chu bi ITU.

+ D p x n m

D /D i D

chu n 1.0(12/1995), 1.1(9/1996), 1.2(12/1996). M y u c p

b tr ng d ch v s li u .

k p n sau (DAVIC 1.3;1.4;1.5) ch y tr

d ch v qu s ch v truy k

+ EEE 2 1 n cho lp v p p MAC cho m ng HFC

s ng. Ph m vi s dng c EEE 2 1 n d q ng

p truy cp Internet t

Bng 2 c tnh ca c c chu n s dng t ng cng ngh Cable Modem

m DOCSIS 1.x Euro-DOCSIS DVB-RC

T ng xung

64-QAM:27Mbps

256-QAM:42Mbps

6 z

64-QAM:38Mbps

256-QAM:52Mbps

z

64-QAM:38Mbps

256-QAM:52Mbps

z

T

320, 640, 1.280,

2.560, 5.120

(Mbps)

QPSK

6 1 280, 2.560, 5.120,10.24

(Mbps)

16-QAM

5-42Mhz

320, 640, 1.280,

2.560, 5.120

(Mbps)

QPSK

640, 1.280, 2.560, 5.120,10.24

(Mbps)

16-QAM

5-65Mhz

1.554Mbps;3.088Mbps

Differential QPSK

5-65Mhz

ch v Truy nhp Internet,

VoIP.

Truy nhp Internet,

VoIP.

Truy nhp Internet,

2 Page 48

T U THAM KH O

[1] D ng truy nhp ng cho h X c vi n CNBCVT,

2007.

[2]. D ng: M truy nhp 6

2010.

[3]. Cablemodem.com

[4]. Internet

[5]. Ph m Th Thu 2 3.

[6]. zz sp s /2

[7]. Cable television technology & operation.

[8] s k

Documents

Mạng HFC Va Công nghệ Cable Modem