giai bai toan tai cau hinh topo logic bang ga

8/8/2019 Giai Bai Toan Tai Cau Hinh Topo Logic Bang GA

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GVHD : ThS Ng Thanh Ngc 1 SVTH : Trn Vn Sang

MC LC

L I CM N............................................................................................................. L I GI I THIU......................................................................................................THUT NG VIT TT..........................................................................................DANH MC HNH V .............................................................................................DANH MC CC BNG....................................................................................MC LC ..................................................................................................................Ch ng 1 : M U................................................................................................ 4 Ch ng 2 : GI I THIU VMNG WDM........................................................... 8

2.1. Gi i thiu hthng WDM ................................................................................. 8 2.1.1. Cng nghWDM......................................................................................... 8 2.1.2.c im chnh ca hthng WDM............................................................. 9

2.2. Cu trc mng WDM ...................................................................................... 10 2.2.1. Cu trc mng WDMim ni im.......................................................... 10 2.2.2. Cu trc mng WDM cnh tuyn b c sng quang ............................... 11

2.3. Cu trc mng WDM ton quang .................................................................... 13 2.4. Mng truy nhp ton quang WDM................................................................... 14

2.4.1. Mng truy nhp ton quang th ng WDM ............................................. 14 2.4.2. Mng truy nhp ton quang tch cc WDM............................................... 14

2.5. Tng quan vmng nh tuyn b c sng....................................................... 15 2.6. Cu trc phn l p ca mng quang .................................................................. 16 2.7. L p quang ....................................................................................................... 18

2.7.1.nh ngh a ................................................................................................. 18 2.7.2. Cc ng quang (Lightpaths) ................................................................... 20 2.7.3. Dch v...................................................................................................... 20 2.7.4. Cu trc ca l p quang............................................................................... 21

2.8. Kt cu topo ca mng WDM.......................................................................... 23 2.8.1. Topo l g?................................................................................................. 23 2.8.2. Topo vt l................................................................................................. 23

2.8.2.a. Hnh tuyn tnh............................................................................................... 232.8.2.b. Hnh sao ......................................................................................................... 232.8.2.c. Hnh vng....................................................................................................... 242.8.2.d. Hnh cy......................................................................................................... 242.8.2.e. Hnh l i ........................................................................................................ 24

2.8.3. Topo logic................................................................................................. 26 2.8.3.a. Hnh sao ......................................................................................................... 262.8.3.b. Topo kiu cn bng ........................................................................................ 262.8.3.c. Topo hnh l i ................................................................................................ 27

2.8.4. So snh topo vt l v i topo logic............................................................ 27


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2.9. ng dng ca WDM trong mng vin thng ngy nay ............................... 28 Ch ng 3 : BI TON TI CU HNH TOPO LOGIC..................................... 30

3.1. Cc cng thc sdng trong bi ton thit ktopo logic ................................. 30 3.1.1. Thng s u vo....................................................................................... 30 3.1.2. Hm mc tiu............................................................................................. 30

3.1.3. Cciu kin rng buc ............................................................................. 30 3.2. Phn tch bi ton ti cu hnh ......................................................................... 31

3.2.1. T ng h p hai mc tiu bi ton ti cu hnh............................................. 31 3.2.2. Chuyn tip cu hnh ttopo logic c sang topo logic m i......................... 32

Ch ng 4 : THUT TON DI TRUYN GA ( GENERIC ALGORITHM )..... 36 4.1. Gi i thiu vGA ............................................................................................ 36 4.2. Cu trc ca thut ton di truyn ..................................................................... 38 4.3. Cc tnh cht c th ca thut ton di truyn.................................................. 40

4.4. Cc b c quan trng trong vic p dng thut ton di truyn........................... 40 4.5. Cc php ton v cc thng sca GA ............................................................ 41 4.5.1 Cc php ton ............................................................................................. 41

4.5.1.a. Php chn lc ................................................................................................. 414.5.1.b. Php lai ghp ( traoi cho ) ........................................................................ 424.5.1.c. Phpt bin.................................................................................................. 42

4.5.2. Cc thng sca thut ton di truyn......................................................... 43 4.5.2.a. Kch th c qun th( Population size )........................................................... 434.5.2.b. Xc sut lai ghp Pc ........................................................................................ 434.5.2.c. Xc su

t

t bi

n Pm

....................................................................................... 434.6. Cc ton tca thut ton di truyn................................................................ 43

4.6.1. Ton tchn lc c th........................................................................... 43 4.6.1.a. Ph ng php chn lc bnh xe Roulettle ........................................................ 444.6.1.b. Ph ng php chn lc xp hng( Rank selection ) .......................................... 444.6.1.c. Phong php chn lc bng trng thin nh ( Steady state selection ) ......... 444.6.1.d. Ph ng phpu tranh ................................................................................... 444.6.1.e. Ph ng php Top-Mate .................................................................................. 45

4.6.2. Ton tlai ghp ...................................................................................... 45 4.6.2.a. Lai ti mt im.............................................................................................. 454.6.2.b. Php lai ti haiim ....................................................................................... 454.6.2.c. Php lai ti nhiu im................................................................................... 464.6.2.d. Php lai t iu chnh phn bccim bt cho ........................................... 464.6.2.e. Php lai Segmented Crossover........................................................................ 464.6.2.f. Php laing nht........................................................................................... 464.6.2.g. Php lai nhiu cha m..................................................................................... 47

4.6.3. Ton t t bin ...................................................................................... 47 4.6.3.a.o bit............................................................................................................ 474.6.3.b. Thayi trt t............................................................................................... 484.6.3.c.t bin o ng c......................................................................................... 484.6.3.d.t bin chn ................................................................................................. 484.6.3.e. t bin thay th............................................................................................ 49

4.7. u nh c im vng dng ca thut ton di truyn...................................... 49


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4.7.1. u im..................................................................................................... 49 4.7.2. Nh c im ............................................................................................... 49 4.7.3. ng dng................................................................................................... 49

Ch ng 5 : P DNG GA VO BI TON TI CU HNH TOPO LOGIC.. 51

5.1. M ha ............................................................................................................ 51 5.2. Hm thch nghi (fitness function)..................................................................... 53 5.2.1. Hm pht ................................................................................................... 53

5.2.1.a. Hm pht t nh................................................................................................. 535.2.1.b. Hm pht ng............................................................................................... 54

5.3. Cc gii php thc hin trong thut ton GA ................................................... 54 5.4. Tiu chun kt thciu kin dng ................................................................. 55 5.5. Cc b c p dng thut ton GA vo bi ton ti cu hnh topo logic......... 55

5.5.1. Kh i to qun th....................................................................................... 55

5.5.2. Kim traiu kin dng............................................................................. 55 5.5.3. Chn lc..................................................................................................... 55 5.5.4. Lai to........................................................................................................ 56 5.5.5.t bin ..................................................................................................... 57

Ch ng 6 : KT QUM PHNG ..................................................................... 58 6.1. Kt qum phng mng 5 node ...................................................................... 58 6.2. Kt qum phng mng 7 node ...................................................................... 63 6.3.nh h ng ca slightpath thayi n gi tr hm mc tiu......................... 66

6.4. Qu trnh tin ha ca thut ton GA............................................................... 67 KT LUN HN CH - H NG PHT TRIN CA TI..................... 69 TI LIU THAM KHO....................................................................................... 71


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Ch ng 1 : M u


CH NG 1M U

Gn y v i spht trin nhanh chng ca internet cn phi c mt dung l ngmng rt l n. K thut WDM ra i hin thc ha khnng tn dng di thng vcng l n ca s i quang, c th xy dng mng din rng v i dung l ng hngterabit/s,c bit l k thut DWDM ( Dense WDM ). Mng WDM cung cp tc d liu rt cao, xc sut li v delay thp c th p ng v i cc ng dng nh supercomputer visualization, medical imaging, v CPU interconnect[11].

S ra i ca cc bkhuch i quang OA ( Optical Amplifier ), bghp knhxen-r quang OADM ( Optical Add-Drop Multiplexer ) v ni cho quang OXC( Optical Cross-Connect ) lm chuyn bin cc mng thng tin quang tmngWDMim ni ( Point-to-Point ) sang mng ton quang ( all optical ).

Hnh 1.1 : Optical Tr anspor t to Optical Networking: Evolution of the Phototonics Layer

Trong cc mng WDMim ni im, tn hiu quang phi c chuyn sangtn hiu in, qua cc b m ri pht li tn hiu quang ti cc node trung gian tr ckhi t n nodech. Qu trnh chuyn i quang-in-quang ti cc node trung gian lm gia tng th i gian trca tn hiu. Mt khc quy trnh chuyn i nyi hicc node phi c b m l n cng nh lm tng sl ng cc bthu pht quang timi node. Trong mng ton quang, mi thng tin c chuyn t node ngun nnodech thng qua mt ng quang ( lightpath ). Mt lightpath l mt ng dn

quang thit lp gia 2 node trong mng, c to ra bng cch phn cng b c sngtrong sut ng dn. iu kin m cng b c sng c lu tr trn tt ccc lin


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Ch ng 1 : M u


kt ca ng dn c xem nh l iu kin rng buc lin tc b c sng. Hailightpath c thsdng trn cng s i quang khi v ch khi chng sdng b c sngkhc nhau. Nu 2 node c kt ni b i 1 ng quang, bn tin c g i tnode nyn node khc m khng cn yu cu bt k b m v bchuyn i quang-in noti node trung gian.

C 2 l p topo trong mng quang: topo vt l ( physical topology ) v topoo( virtual topology ) hay cn gi l topo logic ( logical topology ). Topo vt l gmnhiu nt v lin kt trong mng. Trn topo vt l ca mt mng ton quang, ta c th thit lp ng quang gia cc cp nt, trong ng quang t ng trng cho mt ktni quang trc tip m khng c bt k sbin i in trung gian no. Tp h p cc ng quang gia cc nt to thnh topo logic. Mc d cc ng quang thuc topologic, vic inh tuyn phi thng qua cc lin kt s i quang vt l.

i v i topo vt l ca mng bit v phn b lu l ng ( traffic ) cho tr cgia mt cp nt ngun-ch, thit k c topo logic v mt thut tonnh tuyntrn topo ti thiu ho tc nghn trong mng v i cc rng buc v tr trung bnh gia cp nt ngun-ch v l ng lu l ng (traffic) yu cu x l ti ccnt (cp logic ca topo logic)[1]. Nu bqua rng buc v trth topo logic s kh phc tp v i cc ng quang ctrrt l n (trong phn ny ta ch bqua rngbuc vsb c sng sn c trong mng) .

Vn t ra khi c s thayi traffic phn b, topo logic va c thit kc

l skhng ti u na. Do , vic sp xp li topo logic ti u lm gim hint ng tht thot ( disruption ) lu l ng v lm tng khnng thc thi ca mng cnphi c xem xt.

C nhiu ph ng php khc nhaukim sot s thayi traffic ( c trnhby r h n trong ch ng 6 ).

Ph ng php thnht, bt ckhi no traffic yu cu thayi, mt topom i c thit k li khng quan tm topoo hin hnh. Do topologic thit k t c s tt nht vgi i hn hm mc tiu. Tuy nhins l ng lightpath cn c thayi khi chuyn t trng thi hin hnhn trng thi m i l rt l n. Ph ng php ny gi l new-design method.

Ph ng php thhai, traffic m i yu cu v topoo hin hnh c s dng nhcc thng s u vo (are taken as input) t topo m i v imc tiu ti thiu gi tr hm mc tiu v s l ng l ng lightpath cn c thay i. Ph ng php ny gi l ph ng php ti cu hnh( reconfiguration method ).

Khng ging nhbi ton thit ktopo logic. Qu trnh ti cu hnh topo logicl cn bng gia mc tiu thc hin thit k topo logic v mc tiu gim s thay itrong topo logic. B i v ti cu hnh khng ch thc hin mt ln m n c th thc


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Ch ng 1 : M u


hin nhiu ln bt ckhi no traffic thayi. Vn t ra khi no thc hin ti cuhnh v ti cu hnh bng cch no.

Qu trnh ti cu hnh l qu trnh thit k li topo logic da trn topo vt l,topo logic tr c v ma trn lu l ng m i yu cu sao cho topo logic m i khng

khc nhiu v i topo logic tr c trong khi vn png tt lu l ng m i.Topo logic c thit kv i mc ch ti thiu gi tr hm mc tiu. Topo

logic l p d i cn phi thayi png s thayi nn traffic l p cao. Qu trnhthc hin vic cn bng gi tr hm mc tiu v s l ng topo logic thayi. Gi tr hm mc tiu quyt nh topo thno l tt nht thch h p v i traffic yu cu. S l ng topo thayi quyt nh mc disruption nht nh ca traffic trong mng khichuyn n topoo m i. V bi ton ti cu hnh c thit lp d i dng cng thctheo ph ng php lp trnh tuyn tnh LP ( Linear Programming ) rt phc tp, tn rt

nhiu th i gian.khc phc cc khuyt im trn nhiu nh khoa hc a ranhiu thut ton heuristic khc nhau nhm tm ra l i gii gn ng.

Thc t, bi ton ti cu hnh topo logic c nhiu nh nghin cu quantm v cng b. C nhiu ph ng php khc nhaugii bi ton ti cu hnh c th l gii chnh xc bng cng thc hoc ph ng php d tm. Trong phn ny, strnhby ngn gn nhng ph ng php ny. Gii php thc hin chnh xc l Mixed IntegerLinear Programming ( MILP ) c trnh by trong [9]. Ph ng php s dng cngthc MILP c tm tt nh sau. t T1 l traffic c. t E l tp h p cc ph ng

trnh tuyn tnh m t iu kin rng buc ca bi ton. Gii php V1 ca E v i T1 ld liu vo topoo ti u v i lung traffic T1. By gi v i traffic m i T2, gii phpti u V2 c a ra bng cch gii E v i d liu u vo l T2.t Opt l gi tr hm mc tiu ca T2. Bt k gii php ti u no cho T2 nn cn c gi tr hm mctiu Opt.tm gii php ti u m gn v i v i gii php V1 nht, ph ng trnh Ecn c m rng thm bng cch thm voiu kin rng buc Objective value=Opt ,v t hm mc tiu m i ca vic ti thiu s l ng lightpath thayi. Gisrng s chuyn i b c sng din ra node trung gian. ni rng, rng buc vs lin tcb c sng c gim i. Topoo c thit kv i mc tiu l shop bnh qun, rngbuc chnh l gi i hn sbthu pht ti mi node v tnh khdng ca b c sng dc ng truyn m lightpath c thit lp. Gii php ny th lunt ti u ( ch ntraffic m i). Khng c dphng cho scn bng gia s l ng lightpath thayi vgi tr hm mc tiu. [12] l sbin thca cng thc MILPa ra [9], c a racn bng gia s l ng lightpath thayi v gi tr hm mc tiu. Tuy nhin vicgii bi ton theo ph ng php MILP rt nng nv tn nhiu th i gian khi snodeca mng tng ln.

Trong [10] bi ton ti cu hnh c a ra l cn bng cn bng ti( nghn )trong mng. Nu ti trn lightpath cng cao, th s l ng traffic x l minodenh tuyn cng cao,iu ny dn n tr hng i (queuing delay )scao.


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Ch ng 1 : M u


Cn bng ti trong mng c ngh a l gim b t ti trn lightpath v do gim tr trong hng i ( queuing delay ).trscnh h ng l n khi ti trn lightpathtn gn bng thng ca n. Do tr c xcnh hu ht b i ti trn lightpath.Thut ton trong [10] mc tiu l ti thiu ti trong lightpath.y l bi ton tm kimcc b( local ) bt u bng xcnh mt topo v to thayi cc b( local ) nhchotopolm gim ti trn lightpath. Thut ton cgng tm topo m c mt viimgn ging v i topo hin hnh. Cc topo ln cn c th c xcnh bng cch traoi cc b ( traoi gia cc node v cc lin kt. Trong [10]a ra nhiu ph ngphp traoi trong mng vng ring. Bao gm traoi node ( node swap ) traoi v tr bt k 2 node trong mng, traoi node ln cn ( neighboring node exchange )ov tr 2 node ln cn, chn node ( node insertion ) di chuyn mt noden v tr m itrong vng ring, traoi 2-nhnh ( 2-branch exchange ) chn hai lin kt v traoinode ch chnh ca chng. Cng trong bi bo ny,ra ph ng php traoi 3-

nhnh ( 3-branch exchange ) chn ba lin kt nh stht1,2,3 v tin hnh traoini ngun ca lin kt 1 n ch ca lin kt 2, ngun ca lin kt 2 n ch ca linkt 3 v ngun ca lin kt 3 n ch ca lin kt 1. Traoi 3-nhnh lun nh ccc kt ni ca mt topo. V i nhng biu khc nhaut c cc topo ln cn,ph ng php traoi 3-nhnh ch ra tnh mm do cho vic thayi topo v i (N/3) s la chn v gim ti a ba lin kt cho mi ln thayi. i v i ph ng php traoinode th ln cn c (N/2) s la chn nhng s thayi c thlnn N-1. Straoinode ln cn c N s la chn v mi thayi mt ( disrupt ) ba lin kt. Traoi 2-

nhnh c (N/2) s la chn, nhng c lbmt mt topo khng kt ni. Do trong[10] tc gidng ph ng php traoi 3-nhnh.

Trong [7] a ra ph ng php ti cu hnh qua hai tng ( two-stage approach ),gi i hn s khc bit gia topo c v topo m i gim s tht thot ( disruption )trong mng.

Trong lun vn ny, dng thut ton di truyn GAgii bi ton ti cu hnhtopo logic.


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Ch ng 2 : Gi i thiu vmng WDM


CH NG 2GI I THIU VMNG WDM

2.1. Gi i thiu hthng WDM2.1.1. Cng nghWDM

Cng nghghp knh theo b c sng quang (WDM) l cng ngh trong cngmt s i quang c thtruyn dn ng th i nhiu b c sng tn hiu quang. Tn hiuquang c b c sng khc nhau ti u pht c th p li (ghp knh) v phi ghptrn cng mt s i quang ca ng dy cp quangtruyn dn. u thu tn hiu cb c sng th p c phn gii ra (tch knh) v x l thm mt b c, khi phc litn hiu gc ri a vo ccu cui khc nhau. Chnh v thcng nghny c gil cng nghghp knh chia b c sng quang, hay cn c gi tt l cng nghghpknh theo b c sng (WDM).

Hnh 2.1 : S ch c n ng hth ng WDM

Cng nghWDMi v i snng cp m rng dung l ng, pht trin dch v bng rng (nhCATV, HDTV v BISDN), khai thcy tim nng bng rngca s i quang, hin nay c thm bkhuch i quang s i (EDFA) th WDM cng c

sc hp dn to l n v i mng thng tin hin i.pht trin, nu tt cdy kt ni quang truyn dn trong mt khu vc no

u nng cp thnh truyn dn WDM, chng ta s t chnhng dy kt ni WDMny giao nhau nhng thit b u cho quang (OXC) ly b c sng lm n v nicho dyi v i tn hiu quang, hoc thit b ghp/tch knh quang (OADM) ghp/tch, th trn l p vt l do ng dy kt ni quang to thnh shnh thnh mtl p quang m i.

Cng nghWDM c th c s dng nhiu vng mng khc nhau trongmng vin thng bao gm cc mng x ng sng (mng ng trc), mng truy nhp

Khuech ai tnKhuech ai tnTach tn hi euGhep tn hieu Thu tn hieuPhat tn hieu

Truyen tn hieutren si quang EDFAEDFA

MUXDE-

MUX

Tx1

Tx2

Rx1

Rx2

Tx2 Rx2


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ni ht v cc mng LAN, trong mng ng trc l mng u tinng dng cngnghWDM, sau l mng LAN.

* V tr c a h th ng WDM trong m ng truy n d n:

V tr hthng WDM trong mng truyn dn nh trong hnh 2.2 trong quanhgia SDH v WDM l quan hgia l p khch hng v l p phc v. T ngng v icng nghWDM, tn hiu SDH, PDH v ATMu ch l tn hiu dch vca hthngWDM.

Xt tph ng h ng pht trin ca hthng WDM, kt h p bghp/tch knh(OADM) v bni cho (OXC) sthnh mt l p mng mng truyn dn quang. S pht trin tip theo ca mng truyn dn l phi xy dng mt l p mng d i l pin SDH, tc s tch mng truyn dn v topo thnh hai l p quang vin m h

thng WDM l ht nhn ca l p mng quang.

2.1.2.c im chnh ca hthng WDM- Hthng WDM tn dng ti nguyn di tn rt rng ca s i quang.

- Hthng WDM truyn dn ng th i nhiu tn hiu v sdng cc b c sngc lp v i nhau.

- Thc hin truyn dn hai chiu trn mt s i quang cng nghWDM c th tit kim c l ngu tl n cho ng dy.

- H thng WDM v i cng nghc nhiu ng dng nh: mng x ng sng,

mng qung b, mng cc bnhiu ng, nhiu a ch.

Hnh 2.2 : V tr c a hth ng WDM trong m ng truy n d n

B nh tuyn IP

ATM

OAMHthng WDM

OXC

DXC

L p knh SDH

ATM

L p mchin(NhATM, IP,)

L p knh quangWDM


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- Hthng WDM ghp knh nhng b c sng truyn dn trong s i n mode,khi truyn ng di dung l ng l n c thtit kim sl ng l n s i quang.

- Sdng hthng WDM c thgim yu cu siu cao tc truyn dn iv i linh kin, ng th i c thtruyn dn dung l ng l n.

- C ththc hin cng nghIP trn WDM.- Hthng WDM c tnh linh hot, tnh kinh tv tin cy cao ca cu hnh

mng trong vic nh tuyn, chuyn mch v khi phc mng.

2.2. Cu trc mng WDM2.2.1. Cu trc mng WDMim ni im

Cu trc mng WDMim ni im c xem l n gin nht ca mngx ng sng sdng cng nghWDM.

Mi knh b c sng c sdng truyn ti mt lung d liu ring bit.Tt ccc knh b c sng c th p thnh mt chm sng ti bghp b c sngWDM a vo mt s i quang.

u thu chm sng sau khi t h p nhiu b c sng li s c tch rabng b tch knh WDM. Sau, nhng tn hiu trong mi knh b c sng s cchuyn sang min in qua btch sng quang O/E. Khi, mt knh b c sng ctht ng ng v i truyn dn mt s i quang n mode trong mng SDH.

Trong hnh thc truyn dn hai chiu mt s i quang, cc knh b c sng c th s dng cho chai h ng i v vhoc c thcho chnh thc mt chiu hai s iquang

u im ca cu trc WDMim - im l cho php tng rng bng thngnh truyn c nhiu knh v i chi ph thp.

Tuy nhin, hn chca cu trc ny l bng tn ca mi knh b c sng khng c sdng hiu quv hn chtc ca cc thit b in t lm gy ra hin t ngnghn cchaiin - quang.ng th i linh hot ca cu trc mng ny khng caodo cc kt ni ch sdng mt b c sng c nh


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Hnh 2.3 : H th ng truy n d n WDM i m n i i m

2.2.2. Cu trc mng WDM cnh tuyn b c sng quangCng nghkhthi cho cu trc ny l cc b nh tuyn b c sng trong min

quang, hin nay nhiu kiu b nh tuyn khc nhau c mt trn th tr ng. Kh nng thit lp li cu hnh cho php sdng dung l ng bng tn n mc ti a.

Mng WDMnh tuyn b c sng minh ho hnh 2.4, mng gm c mt photonic switching fabric, bao gm active switches kt ni cc lin kt s i quangtrn topo vt l bt k. Mi end-user c kt ni n mt active switch thng qua linkt s i quang. Kt h p end-user v chuyn mch t ng ng ca n c xem nh lmt node mng.

Mi node ( ti trm truy nhp ) c trang b cc b thu pht, chai b thu vpht c thlinhiu h ng b c sng. Bpht ti mt node sg i d liu vo mngv bthu thu dliu tmng.

Cu trc cn bn truyn thng trong mng nh tuyn b c sng l lightpath.

Mt lightpath l tt ccc knh thng tin gia 2 node trong mng, v n c thninhiu h n mt lin kt s i quang. Node trung gian trong ng dn s i quangnhtuyn lightpath trong min quang s dng active switch . Node kt cui ca lightpathtruy cp lightpath c bpht v bthu nm bt c b c sng m lightpath vnhnh. V d trn hnh 2.4, lightpath c thit lp gia node A v node C trn knhb c sng 1 , gia B v F trn knh b c sng 2 , gia H v G trn knh b c sng

1 . Lightpath gia A v C c nh tuyn qua active switch 1,6 v 7. ( Ch vic s dng li b c sng 1 ).

V khng c thit b chuyn i b c sng no, mt lightpath phi c cngknh b c sng trong sut ng truyn trong mng. S rng buc ny gi l lin t c


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b c sng Rng buc ny skhng cn thit nu c bchuyn i b c sng. V d trong hnh 2.4 lightpath gia node D v Ei qua (traverse) lin kt s i quang tnodeD n switch 10 l b c sng 1 , chuyn i thnh 2 ti switch 10,i qua lin kt s iquang gia switch 10 v switch 9 l b c sng 2 , chuyn i li b c sng 1 ti

switch 9, vi qua lin kt s i quang tswitch 9n node E l b c sng 1 .

Hnh 2.4 : M ng WDM nh tuy n b c sng

Yu cu c bn trong mng nh tuyn b c sng quang l hai hoc nhiulightpathi qua cng lin kt s i quang phi c knh b c sng khc nhauchngkhng gy xo trn cho nhau.

Hn chca cu trc ny l vn nghn c chai cc nt TDMin tvncn tn ti. Bn cnh , mt svn k thut vn cn c xem xt gii quyt hon thin i v i cu trc ny bao gm hthng iu khin cho vic thit lp li cuhnh kt ni, nh gi lu l ng gia cc knh WDM v gia cc s i quang, cng nh cng nghchto cc b nh tuyn.

gii quyt tt vn cn tn ti, cu trc mng WDM ton quang c ra i.


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2.3. Cu trc mng WDM ton quang

Hnh 2.5 : C u trc m ng ton quang

Mng ton quang phn thnh 3 l p con: level 0, level 1, level 2. Mi l p con lmt vng ton quang c khnng thot ng.

Level 0: Biu din mng ni ht (LAN) c sl ng rt l n.

Level 1: Biu din mng th (MAN) ly thnh phhay khu vc hnh chnhlm n v, th ng c cly vi Kmn vi chc Km.

Level 3: Biu din mng din rng (WAN) l mng ng trc trong phm viquc gia, cly th ng vi trm n vi nghn Km.

Hai c im quan trng ca s i trong mng ny l suy hao thp v di thngrng.

Mng phc v3 l p dch v: A, B, C. Dch v l p A v B c thl im ni

im hoc a im ni a im, kt ni n cng hay song cng. Dch v l p C ldch vgi.

Hai cng nghcho vic s dng di thng ca s i quang l WDM v TDM.c im ca mng WDM ton quang l khnng nh tuyn b c sng.nh tuyncung cp mt ng truyn nh sng trong sut gia ccu cui mng. Mt ngtruyn nh sng l ng m mt tn hiu quang trong mng tngun n ch c th bao gm s thayi b c sng ton quang. Mt ng truyn khng c s thay ib c sng. S trong sut ny cung cp cch n gin nht cho cc user khngng

nht chia sti nguyn.


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2.4. Mng truy nhp ton quang WDMVcu trc mng truy nhp quang c th c chia thnh 2 loi: mng truy

nhp th ng WDM, v mng truy nhp tch cc WDM.

2.4.1. Mng truy nhp ton quang th ng WDM

Mng quang th ng (PON) WDM sdng cc knh b c sngkt ni ccusers v i trm trung tm (CO). PONu tin c pht trin cho cc dch vbng hp.Tuy nhin, nhng mng PON gn y dng cho cbng hp ln bng rng.

Cu trc mng ny khng sdng cc thit b tch cc bn ngoi CO, nhng nh khch hng th phi sdng cc thit b ny v mi b c sng smang mt dchv.

Nhiu cu trc mng quang th ng c xut cho cng nghWDM

bao gm cu trc sao n, cu trc hnh cy, cu trc hnh sao kp v cu trc sao-bus. 2.4.2. Mng truy nhp ton quang tch c c WDM

Trong cc mng truy nhp DWDM th ng, mi knh b c sng ch sdngmang mt dch vti mt th i im xcnh m khng cn quan tmn bng tnv dung l ng m dch vyu cu, trong khi bng tn ca knh tn hiu c th l nmang mt sdch vkhi thc hin cng nghWDM trong mng a truy cp.

Trn c s ny, k thut TDM c ng dng trong mi knh b c sng tora mng truy nhp quang WDM tch cc trong cc thit b TDM c sdng cung cp cho cc dch vtch h p v cng nghATM c xem nhgiao thc TDMni bt trong cu trc mng ny.

Cu hnh mng truy nhp quang WDM tch cc cng ging nh trong mngtruy nhp quang WDM th ng.

* H n ch ca mng truy nh p tch c c WDM so v i mng truy nh p th ngWDM:

Mc d mng truy nhp WDM tch cc c thtn dng trit cc knh b csng v gim chi ph vs i quang, nhng nh cung cp mng cn lu l phi b sung thm chi ph cho cc thit b ATM trong hthng t tng i n nh thu bao.Cu trc mng ny cng lm tng thm mc phc tp trong qu trnh bo d ng vqun l hthng, lm chi ph vn hnh cao.

Do vy khi cng nghWDM pht trin, sl ng knh b c sng trong mt s iquang tng ln th mng truy nhp quang WDM th ng c thl cu trc c utin trong cu trc mng truy nhp.


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2.5. Tng quan vmng nh tuyn b c sngMng WDM ton quang c sdng nh tuyn b c sng c xem lng c

vin quan trng nht cho cc mng ng trc din rng thhtip theo. Topo vt lca mng bao gm cc b nh tuyn quang kt ni v i nhau bng cc cp lin kt s i

quangim ni im trong mt topo mng l i bt k ( hnh 2.6 ).Trong hnh 2.6 micp lin kt c t ng trng bng mt cnh v h ng gia cc ntnh tuyn. Nt u cui kt ni v i b nh tuyn. Mi ntu cui c sbpht v b thu gi i hn.Trong hnh 2.7 ntnh tuyn thu tn hiu ti mt b c sng xcnh ng vo can, sau nh tuyn tn hiu ny (c lp v i cc b c sng khc)n mt ng rano . B nh tuyn c Dp ng vo vDp ng ra c khnng x l L b c sngging nh L bchuyn mch b c sngDp Dp cu hnh li c.

Hnh 2.6 : M ng WDM g m nhi u nt nh tuy n k t n i b ng cc c p lin k t s iquang i m n i i m. Cc nt nh tuy n g n v i cc nt u cu i hnhthnh cc nt ngu n v ch cho l u l ng trong m ng.

Ntnhtuyn

Ntu cui- chuynmch ATM

ng quang

4

3

2

1

A C

B

D

TOPO VT L


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Hnh 2.7 : C u trc c a b nh tuy n c u hnh l i. B nh tuy n c th chuy n mchm i b c sng ng vo c l p v i cc b c sng khc.

2.6. Cu trc phn l p ca mng quangTrong cu trc tng quang bao gm nhiu l p tIP, ATM v SONET/SDHn

l p quang.

Khi nim v l p c th c s dng gip chng ta pht trin mt imm i ca ci nhn vmng. Ly v d, ton bmng c th c xem nh l tp h pcc dy l p, mi l p i din cho mt hthng truyn dn, v d l mng SONET v

ATM. ATM c pht trin cho truyn dn qua mng SONET [11]. Do, tmtquan im logic, ton bmng ch c mt l p cao h n (ATM) v mt l p thp h n(SONET) c trnh by trong ( hnh 2.8a ).

Vmt vt l, khi nim ny c th c cho tcng b i kt ni chuyn mchATM v i card adapter (png) SONET,t c truy nhp ATMn mng SONET.Mt ngun a s liu n mng ATM, n i m lung s liu c chuyn i thnhcell ATM. ATM chuyn mch trc tip nhng cell nyn card SONET. SONETchuyn i cell ATM thnh khung STS v truyn nhng khung ny qua mng. Ti

cui u thu, SONET chuyn i nhng khung ny tr li thnh cell ATM vanhng cell nyn chuyn mch ATM, n i a trc tip nhng celln ch ca n.iu ny c trnh by nh( hnh 2.8b ).

Vn cn mt v dna l truyn IP qua mng ATM. Trong tr ng h p ny, IPtp trung qua l p ATM, l l p nm ngoi l p SONET ( hnh 2.8c ). Phn vt l thchin hon thnh b i kt ni nh tuyn IP n mng ATM. Gi IP pht ra tmtngun c phn phtn nhng b nh tuyn IP. Nhng gi ny c chuyn ithnh cell ATM. Nhng cell ny c truyn qua mng ATM v chuyn i ng c li

thnh gi IP ti ngoi vi ca mng ATM. Router IP chuyn nhng gi nyn chca chng (Xem hnh 2.8d).

l 2

l 2l 2

l 2

l 2l 2

1

l 1

l 1l 1

l 1

l 1

l 2

l 1

l 1l 2

l 1l 2

l 1l 2

Chuy n mch quang

Chuy n mch quang

Tch b c sng Ghp b c sng

l 1l 2

l 1l 2

l 1l 2


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18/71



Physical l ayer

Section l ayer

Line layer

Path layerATM layer

ATM Adaptation layer

Data Link layer

Network layer

S O N

E T A

TM

I P

Hnh 2.9 : C u trc phn l p mng IP over ATM over SONET

Khi lu l ng trong mng thng tin quang tng ln, n cng lm tng cmong sdng IP trc tip qua SONET.

Trong phm vi nghin cu ca lun vn ny, tp trung vo vic thit k l pquang, l l p cung cp cc ng ni tc cao, thng qua cc lightpath.

2.7. L p quang

2.7.1.nh ngh aITU-T gi i thiu mt l p m i cho mng vin thng, l l p quang. Cu trc

l p ca mt mng hin i, bao gm mt l p quang, c trnh by hnh 14.21. Hnh14.21a v ba n mt ci nhn chung [1], trong khi hnh 14.21c kt h p cci nhnvt l v logiccho thy l p SONET c t nhthno v i l p quang v sktni gia nhng im ca chng.

Vmt vt l, ng truyn WDM l h thng im ni im, ni cc thnhphn SONET. Do, WDM l mt l p vt l m chuyn nhng khung SONET khng

tc ngn overhead SONET.C thhiu c nu nhvo lc ny bn ang thi ti sao chng ta cn mt

l p quang,c bit l tt cnhng g chng ta ni chon gi u nhm thuyt phcbn rng hu ht struyn dn hin nayu qua cp quang. Hy lm r ny : Truyndn vt l trong SONET, ATM v IP c thc hin b i h thng truyn thng cpquang m chng taang tho lun. Cu trc logic ca mng cp quang ny, tuy th,khng bao gm mt l p quang, nhhnh 2.8c trnh by.


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Lightpaths

SONET

ATM

IP

Optical layer

SONETConnections

Applications

Virtualcircuits

ATM

Connections

Virtualcircuits

a)

SONETlayer

Opticallayer

c)

b)Optical layer

FDDIIPATMSONET ...

Hnh 2.10 . C u trc phn l p ca mng fiber-optic trn l p quang a) IP over ATM over SONET over Optical layer

b) Network layers immediately over Optical layer c) SONET layer over an Optical layer

Mc d mi tr ng truyn dn cho mng hin i l cp quang, phn l n thitb cit v bghp knh xen/r t vn l in t. l l do ti sao chng ta xemnhng mng ny l thhmng cp quangu tin. L p quang m i ny c thit lpv i thhmng quang thhai. L p quang ny phc vkhng ch nhmt mi tr ngtruyn dn, m cn mang li tt cnhng chc nng v dch v i hi b i mt khinim l p.

Thhmng cp quang th hai cung cp khng ch kt ni quangim niim m cnnh tuyn v chc nng add/drop (xen/r t) trong min quang. Tkhi cmng WDM, tt ccc chc nng c kt h p v i knh b c sng.

L do chng ta cn mt l p na v i chc nng v dch vging nhnhng l p tn ti nh SONET hoc ATM l mi l p mng Quang, SONET, ATM, IP-hot ng c hiu qu trong phm vi bit ca n. Truyn dn hng terabit/s bao gmnhiu knh b c sng, mi knh b c sng gm c nhiu lung s liu nh c tob i cng nghTDM. N c hiu quh n v i vic giao cho l p quang hot ng mc Tbit/s, m khng bao gm truyn mc Mbit/s, n i m l p quang hot ng khnghiu qu. Ngoi ra, SONET c thit k dng d liu hot ng hiu qunht mc Mbit/s, nhng khng hot ng hiu qu tc Tbit/s. Mong mun ti u hotng ca mi l p l ng lc c bn trong s pht trin ca khi nim cu trc l pmng thng tin quang [11].


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Cu trc l p trn hnh 2.10a hot ng hin nay tt nhng n c mt hn chc hu : Cng nhiu sl ng giao din l p trong truyn dn, mng cng tr nn phc tp.C ngh a l gim s tin cy v gi thnh cao. Tuy vy, spht trin ca mng thngtin quang ngy nay cho php nhn vin mng thc hin SONET, ATM, IP, FDDItrn mt mng quang chung, c ngh a l tt cnhng l p c cp trn c t trn mt l p quang, nhhnh 2.10b m t.

2.7.2. Cc ng quang (Lightpaths)L p quang cung cp lightpathn l p cao h n [11]. Lightpath l mt knh

thng tin quang tm th i c thit lp trn mng. Ngoi ra, n cng c ngh a cungcp ng truyn end-to-end xuyn qua mt mng quang. S dng lightpath, c th truyn d liu dng b c sng n hoc thm ch s dng li b c sng (xem hnh2.6). Tnh linh hot ca lightpath c thlm cho l p quang cung cp s sdng y

di thng ca mng. Nhn li hnh 2.10 ln na, ch rng ATM hay LAN hoc bt k mt l p

mng khc, c th t pha trn l p mng m khng cn dng l p xen vo.

2.7.3. Dch v - Ci t lightpath l mt kiu dch v u tin m l p quang cung cp cho

l p trn. Thit lp lightpath c ngh a l thit lp kt ni gia tt cng i dngucui trong ton bmng. Chng ta c th a ra mt s t ng t v i PSTN (mngin thoi chuyn mch cng cng) l thit lp lightpath trong mng thng tin quangging nh thit lp kt ni vt l bn trong chuyn mch mch PSTN. Thit lplightpath hon thnh lc c yu cu ca ng i dng v kt ni kt thc khi cuc mthoi xong, mt hnhng ging nh trong hot ng PSTN, n i m kt ni giang i gi v ng i b gi c thit lp lc c yu cu ca ng i gi v kt thc b is ng chung.

Lightpath th ng c kt h p v i b c sng n trong h thng thng tinquang WDM, mt knh b c sng ring ltiu biu c tc bit cao (2,5 Gbit/s). B i

vy, lightpath biu th ton bdi thng ca l p trn.- Kiu dch v thhai m l p quang cung cp l thit lp mch o. Mch o

l kt ni chuyn mch gi gia nhng im. Scn thit dng mch o c th chiu qua vic xt v d : Gis rng bng thng ca ng truyn l 2,5 Gbit/s,inhnh ca knh b c sng n ngy nay; tuy vy, bn ch cn 155 Mbit/s. Khng cmcho, bn schim gi ton b ng truyn, mt cch khng hiu qu sdngkhnng ca mng.

Chia nh ton bdi thng thnh nhng phn nhh n, mt l p quang sdng

cng nghOTDM (ghp knh quang theo th i gian).Tr li v i v d trn, d liu s c truyn gia 2 im v i tp h p nhng gi truyn v i tc 155 Mbit/s. Lung


21/71



ny c ghp knh quang theo th i gian v i nhng d liu khc, do tc caton b knh l 2,5 Gbit/s.iu ny cho php ng i thit kmng lmy ton b bng thng ca ng truyn v i nhng phn nh h n. Nhng ngy nay mng hotng bng v i tc truyn nu nhc mt chuyn mch c nhn. Do, cng ngh ny c gi l virtual circuit (mcho).

- Kiu dch v th ba, mng quang cung cp n l p trn dch vdatagram(gi d liu) - a n truyn dn nhng gi d liu nhm khng thit lp kt nitr c khi truyn dn tht s.

2.7.4. Cu trc ca l p quangTt c nhng l p mng SONET, ATM, IPu cha nhiu l p con. L p

quang cng khng ngoi lv cu trc ca n c trnh by trn hnh 2.11.

Chng ta sxem xt nhng on nm ngang ca h thng WDM. T quanim ny, ton bmng c chia nh thnh nhng on gia hai im WDM k nhau v/hoc mt im WDM v mt im khuch i quang. Mi im c mt cutrc l p ring, c trnh by trn hnh 2.11. Hy xem xt cu trc ny [11] :

Optical Transmission Section layer (l p on truyn dn quang), c m t nhAmplifier layer (l p khuch i), trong hnh 2.11, c ti mi im v cung cpchc nng khuch i cho l p trn.

L p on ghp knh quang ( Optical Multiplex Section layer )c trng cho

kt ni im ni im gia nhng im WDM dc theo ltrnh ca ng quang).L p on knh ( Channel Section layer ), cng c gi l l p on knh quang

( Optical Channel Section layer ) hoc l p ng quang ( Lightpath layer ) c nhimv nh tuyn ng quang end-to-end xuyn qua ton bmng.


22/71



a)

OXC

OA

OADM

OA

OXC

Opticallayer

SONET, ATM, IP, FDDI, and other clients

Optical Channel Section layer

Optical Multiplex Section layer

Optical Transmission Section layer(Amplifier layer)

Optical interfaces (OCXs, OADMs, and Oas)

Hnh 2.11 : . C u trc c a mt l p quang :

a) Cc on ca mt l p quang (Sections of an optical layer)

b) Cc l p con c a mt l p quang ( the sublayers of an optical layer )

Xem li hnh 2.8 v 2.11, mng IP c chy trn mng ATM, v mng ATMchy trn SONET, nhhnh 2.8c trnh by. Cu trc l p ny ca ton bmng cvchi tit trn hnh 2.9, n i trnh by tt cl p con ca l p mng. Hnh 2.10 tip tcpht trin strnh by trn hnh 2.8 bng vic ch ra tt ccc l p chyu, bao gm c l p quang. C thddng vchi tit cu trc ca mng thng tin quang nhhnh 2.9b i vic kt h p chnh 2.9 v 2.14. Ch rng l p quang phc vnh l p vt ltrong mng SONET.

M hnh ca l p quang c gi i thiu b i ITU-T v c m t nh trnkhng phn nh tt cchc nng kt h p v i thhmng quang th hai. c bit,trong broadcast (bng rng) v mng thng tin quang, chc nng chuyn mch gi c hot ng b i Media-Access Control layer (l p iu khin truy nhp truynthng) ; tuy vy, l p ny khng c trnh by trn hnh 2.11. Trong mng nh tuynb c sng (wavelength-routing network) ( xem phn 2.2.2), chc nng chuyn mchgi c hot ng b i Network layer (l p mng) - khng c trnh by trn hnh2.11. M hnh ca mt l p quang cn c pht trin thm na nhmng thng tinquang tin trin. Hy nhn vo nhng tin tc cng b th ng mi vspht trin m inht cc l p quang, ha hn sni ln cng ngh trong quang cnh truyn thng tinquang.


23/71



2.8. Kt cu topo ca mng WDM2.8.1. Topo l g?

Topo tc l hnh th mng, bt k mng thng tin no cng c 2 loi kt cutopo: topo vt l v topo logic (hay topoo).

Phn loi topo :- Topo vt l : m tcu trc vt l ca im nt mng.

- Topo logic : m tsphn bdch vgia 2im nt mng.

2.8.2. Topo vt lTopo vt l ca mng l mt tp cc ntu cui, ntnh tuyn v cc lin kt

s i quang kt ni cc nt v i nhau vmt vt l m trn, ng i ta c ththit lp ng quang gia cc ntu cui. ng quang l mt ng dn i qua mng c cp pht b c sng gia cc ntu cui, v c thit lp bng cch cu hnh ccnt nh tuyn trong mng. Hai ng quang dng chung mt lin kt phi s dngb c sng khc nhau. ng quang cung cp mt ng thng gia hai ntu cuiv i bng thng bng v i bng thng ca mt knh, th ng l 2.5Gb/sn 10 Gb/s.

Topo vt l thc hin trn b ghp/ tch quang (OADM) v b kt ni choquang (OXC). Ngoi ph ng thc kt ni n gin im ni im, cc topo vt l s dng trong mng quang cn c my loi d i y :

2.8.2.a. Hnh tuyn tnhKhi tt cccim nt ca mng ni v i nhau theo kiu ng dy khng khp

kn, ta sc topo hnh tuyn.

im nt u trong cu trc ny thc hin chc nng ghp knh b c sng,im nt gia l thit bOADM.

u i m : C thlinh hot, dlp t ccu ni tr khng thp trn cc bus(th ng l ng dyng trc) m khngnh h ngn hot ng ca ton mng.

Nh c i m : Tnh tn ti ca n t ng i thp b i v khi mt im nt hoc ng dy kt ni ca mng b scth mng l i khng thhot ng c.

truy nhp n cc bus dliu quang phi dng cc bcouplers.

2.8.2.b. Hnh sao

Trong tt c cc im nt ca mng ch c mt im nt kt ni v i ttcccim nt cn li, im nt ny gi lim nt trung tm (central node hay hub).Ccim nt cn li gi l ccim nt phthuc (outlying), khng c cc kt ni vtl gia ccim nt ny nn thng tin gia chng phi chuyn tip quaim nt trungtm (chuyn tip in hoc quang).


24/71



im nt trung tm c th l 1 thit b th ng hay tch cc. Nu s dng 1thit b tch cc, t im nt trung tm c thkim sot tt ccc ng nh tuynthng tin trong mng. Nu sdng 1 thit b th ng, th ti im nt trung tm phit b tch cng sut chia cc tn hiu quangu von tt ccc ng ng ra i n cc trm phthuc.

u i m: To iu kin thun l i cho vic qun l tng h p bng tn ca mng.

Nh c im: Ph thuc voim nt trung tm, nn t c hiu qus dng mng i hi im nt trung tm phi c khnng x l rt mnh lu thotcc dch vthng tin gia im nt phthuc v i im nt trung tm v gia ccimnt phthuc v i nhau.

2.8.2.c. Hnh vng

Cc im nt mng lin tip nhau c kt ni bng nhng lin kt im niim v to thnh mt vng kn.

Cu trc t ng tnh topo hnh tuyn nhng haiim ntu cui u dngthit b OADM v dng ng dy cp quangni chng li v i nhau sto thnhtopo hnh vng.

Trong topo hnh vng, gia haiim bt k ca mng u c hainh tuyn dingn khc nhau, truyn dn ng c chiu nhau,iu ny to nhiu thun l i trong vnbo vmng.

D liu di chuyn trong mng vng d i dng gi t nt mng ny sang ntmng khc. Ti mi nt mng l mt thit b tch cc c khnng nhn ra a ch cacc gi dliu nhn ng thng tin gi cho n hay cho nt mng khc.

u im: C tnh nng bo v tt, thc hin n gin, hot ng hiu qu, cth ng dng trong mi tr ng h p.

2.8.2.d. Hnh cy

Mng hnh cy l kt h p gia topo hnh sao v i topo hnh tuyn, c thxem

nhl sm rng ca topo hnh sao.2.8.2.e. Hnh l i

Gia tt ccc im nt ca mng t nht c 2 ng dy kt ni vt l khcnhau, nu kt ni khng c dng hnh vng sl hnh l i. Nu nhc2 trong tt c ccim nt c kt ni vt l v i nhau th sto ra mng hnh l i l t ng.

Ccim nt mng th ng l bOXC.


25/71



Hnh 2.12 : Topo v t l d ng hnh tuy n

Hnh 2.13: Topo v t l d ng hnh vng

Station 1 3

N-1

N

2

Station Station

Station Station

Optical couplers

Bus trunk li ne

Station attachment l ines

Station attachment l ines

Station

Station

StationStation

Optical coupler

1

2

3

iFiber optic trunklines

NStation


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27/71



2.8.3.c. Topo hnh l i

Tt ccc im nt trong mng u c thkt ni thng tin ra, hu ht cc cpim nt tn ti knh thng tin trc tip.

u i m : Linh hot, hot ng rt mnh.

Nh c i m : vic iu khin v qun l.2.8.4. So snh topo vt l v i topo logic

C lin quan trc tip v i vic nhtuyn khit ng cp quang, tuy nhintopo vt l khng th theo kp s phttrin ca dch v v topo vt l c th xem l topo cng.

C lin quann khi nim knhquang v i s phn b dch v gia ccim nt, c th thay i topo logic t ch ng trnh phn mm nn c thxemtopo logic l topo mm.

C s ca topo vt l l kt ni vt lgia ccim nt.

C s thit kca topo logic l quanhkt ni logic gia ccim nt.

Phn nh quan h kt ni trong l pvt l, mc phc tp ca topo vt lphthuc vo s l ng u dy ca imnt mng.

Phn nh cc kt ni trong l p knhquang ca mng. Cht l ng truyn dnv x l, phc tp ca kt ni logicphthuc vo s l ng u dy ca imnt mng, sl ng b c sng ghp knh,chc nng v kt cu ca mng.

Mc ch thit k topo vt l l png nhu cu dch vmng, do yucu thit k cc kt ni sao cho ti ugia ccim nt mng.

Mc ch thit k topo logic l nng cao kh nng vn hnh v kinhdoanh ca mng, ti u ho chc nngmng ca l p knh quang da trn topovt l.

B ng 2.1: So snh topo v t l v i topo logic

Hnh 2.15 trnh by topo logicng v i topo vt l trong hnh 2.6, topo logic nyt ngng v i mt tp cc ng quang trong hnh 2.6. Topo logic l mt th v icc nt t ngng v i cc ntu cui trong mng gc, v mt cnh c h ng tntB n nt A nu ng quang c thit lp t nt B n nt A. Cp vt l(physical degree) ca mt nt nh tuyn l s l ng cc ntnh tuyn kt ni trctip v i n bng cc lin kt s i quang (v d cp vt l ca tt ccc ntnh

tuyn trong hnh 2.6 l 2). Cp logici (logical out-degree) ca mt nt u cui ls ng quang bt ngun tnt v cp logicn (logical in-degree) ca mtnt u cui l s ng quang kt cui ti nt, v d, trong hnh 2.15, cp logic


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i v cp logicn ca mi ntu cui u l 1. Gis rng mi ntnh tuynkt ni v i mt ntu cui duy nht v ng c li, th n gin ta ch ni n cp logic v cp vt l ca mi nt.

Hnh 2.15 : Topo logic cho m ng hnh 2.6. Cc c nh c h ng trong topo ny t ng

tr ng cho cc ng quang gi a cc nt u cu i t ng ng trong hnh 2.6

2.9. ng dng ca WDM trong mng vin thng ngy nay

Mc d pht trin trong nhng nm gn y nhng cng nghWDM( DWDM ) vn l mt trong nhng ch mang tnh th i sca l nh vc h tng c s mng.

WDM khng ch c coi l mt ph ng tin nng dung l ng cp quang

m cn l mt cng ngh ng dng trong mng ng trc a dch vvcc mng truy nhp di ng v n c khnng lin kt v i cc cng ngh m i nhATM, IP, ADSL.

Mng WDM ngy cng c sdng nhiu h n p ng nhu cu mngca khu vc v nhng n i tp trung dn c v khng ch xy dng ccmng hin ti v cung cp bo mt v tnh khdng cao.

Tuy nhin, nu so s nh vi cc mng cp ng di truyn thng th cngtc trin khai trong khu vc ng dn c li c nhng thch thc ring. V d, c im nng ng ca cc khu vc dn c thnh th i hi mng vtl phi png nhanh chng nhng thayi vnhu cu hoc lu l ng nh b sung hoc b t i cc d liu mi nt, trong chi ph lp t v bod ng khi thit kmng WDM l mt vn cn quan tm.

mt kha cnh khc, tnh linh hot v dung l ng l n khin cho WDMtr thnh cng nghl t ng cng ccho spht trin ca cc mng dchv thhtip theo ( mng NGN ), cho php WDMpng yu cu lul ng t cc mng khc nhau, d l c nh hay ding, d cc dch v ngy cng phc tp, sng i sdng ngy cng v t tri.

B

A

D

C


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Mng WDM ch l mt phn trong bc tranh ton cnh vthng tin quanghin nay, mt trong nhng mng pht trin nht l SDHi km v i cc h thng c ITU xc nhn.

Trn thgi i gn y, M, n i thng tin quang pht trin mnh m, l quc

gia u tin trin khai mng WDM, v ngy cng c ng dng rng ritrn th tr ng Chu u, Chu v Chu M La Tinh.

Xy dng mng WDM s a vo thit b kt ni cho quang OXC v thitb ghp/tch knh quang OADM v bin i b c sng quang trnim ntni cho nhau ca mng ng trc, t hnh thnh knh b c sngo t u n cui.

Ti Vit Nam, SDH OFC l mc tiu pht trin ca cc nh khai thc v s c m rng trong cn c chon nm 2010 v nhu cu vdung l ng v

tc ca dch vni chung cha cao lm. Khi noi hi vdung l ng ng truyn trn tuyn ng trc cao h n th gii php mng WDM cthl mt gii php thch h p.


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Ch ng 3 : Bi ton ti cu hnh topo logic


CH NG 3BI TON TI CU HNH TOPO LOGIC

Bi ton ti cu hnh l bi ton ti u c rng buc. Ti cu hnh c thchin khi c s thayi traffic yu cu, khng phi l skhng thch h p ca thit b cng khng phi l sthayi trong topo vt l.Trong ch ng ny tin hnh phn tchbi ton ti cu hnh v cc cng thc sdng trong bi ton.

3.1. Cc cng th c s dng trong bi ton thit ktopo logicBi ton thit ktopo logic c t ra nhm xcnh cc ng ni logic cn thit to thnh topo logic ti u, c khnng p ng yu cu truyn thng tin tt nhttrongiu kin rng buc vsl ng b c sng v khnng phn cng ca mng.

3.1.1. Thng s u vo Topo vt l : topo ca mng cp quang cth

Traffic yu cu : nhu cu kt ni gia cc node trong mng

3.1.2. Hm mc tiuTrongti ny, h ngn mc tiu ti thiu shop trung bnh

.sd sd s d

sd s d

t h Havg

t =

V i

Havg : s hop logic trung bnh m lung traffic phi v t khi truyn t ngunn ch

sd t : l ng traffic cn truyn tngun s n ch d

sd h : shop m traffic phi v t qua khi truyn tngun s n ch d

3.1.3. Cciu kin rng buc Sl ng thit b thu pht quang ti mi node

Dung l ng mi ng quang

S hop logic l n nht m mt lung traffic phi v t qua khi truyn t

ngun n ch Sb c sng ti a c thtruyn trn mi s i quang


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Chiu di vt l m cc ng quang phi truyn qua.

3.2. Phn tch bi ton ti cu hnhBi ton ti cu hnh l bi tona mc tiu m khng ch thc thi trong mng

m cn kim tra s thay i trong topo logic. Hiu r h n khc bit so v i thit k

topo logic thng th ng l n cn yu cu mc tiu khc ( ti thiu s lightpath thayi trong topo logic ) bn cnh mc tiu thc thi trong mng.

Cng thc sdng trong bi ton ti cu hnh th t ng tnhbi ton thit k,nhng trong phn ti cu hnh chng ta khng ch thc hin n thun trong mng mcn phi gim ti a sthayi c to ra trong qu trnh ti cu hnh

Bi ton thc hin qua 2 phn

Phn 1 : t ng h p hai mc tiu bi ton ton ti cu hnh to topo logic

m i Phn 2 : chuyn tip cu hnh ttopo logic c sang topo logic m i

3.2.1. T ng h p hai mc tiu bi ton ti cu hnhV bi ton ti cu hnh topo logic c hai mc tiu, m hai mc tiu c xungt

( conflict ) v i nhau, nu thayi ca topo m i so v i topo c tng th gi tr hm mctiu gim v ng c li. Nn cn phi t ng h p hai mc tiu ca bi ton.

Do i hi phi c hai thng s u vo l ma trn traffic m i yu cu v

topo logic hin hnh. Chng ti tnh ton bi ton ti cu hnh nhbi ton lp trnhtuyn tuyn tnh LP( Linear Programming ) [9]. t ng h p v i hai mc tiu trongLP, chng ta phi thit lp mt mc tiu nhmt hng strong khi LP ti u ci khcv lm ln l t.

u tint NoChange l s lightpath thayi, mc tiu bi ton lc ny l tithiu shop trung bnh

.sd sd s d

sd s d

t h Havg

t =

Tip theo thm vo mt rng buc m i

'sd sd s d

V V NoChange-

V i

'sd V : slightpath tnode sn node d trong topo logic m i

sd V : slightpath tnode sn node d trong topo logic c


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Bi ton lc ny tr nn n gin h n rt nhiu. Thay v gii v i hai mc tiubi ton lc ny ch gii v i mt mc tiu l ti thiu l shop trung bnh v i cc rngbuc.

3.2.2. Chuyn tip cu hnh t topo logic c sang topo logic m i

Tp h p cc lightpath trong topo logic m i c xc nh b iw

w { | 1,2,.... }nene i L l i n= = . Cho rng cc lightpath m c sdng chai topo c v m iskhng b thay i. Cc lightpath c m sdng bt k ti nguyn nhb c sng,bthu pht gy xungt v i topo m i sb xo b( torn down )thit lp lightpathm i. Xungt gia topo c v topo m i c trnh by r trong biu ph tr ( auxiliary grap )

Hnh 3.1: Bi u xung t gi a lightpath c v lightpath m i

(a) old L

(b) wne L

(c) bi u phtr Ga(V a ,E a)

wa old neV L L= w{( , ) |ne old a i j E l l= nu

ww

nei nel L xungt v i }old j old l L wa old neV L L=


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Ch rng mi xungt ny c ll kt quxungt vb c song v b thupht. H n na mi mt lightpath m i c xungt v i cc lightpath c. ( xem hnh v).

B i v chuyn tip ti cu hnh ( reconfiguration transiton ) c l l nguyn

nhn gy ra ch s trv mt gi tin, n cng lim ct li thng bo hiu qu phn b lu l ng yu cu ca mng trong sut qu trnh ti cu hnh. Gi inh rngkhng c tht thot lu l ng, cc lu l ng trn lightpath b xa b s c nhtuyn li n ng khc bng cch s dng thut ton tm ng i ngn nht( shortest path algorithm ). Vic thit lp lightpath m i s c dnh cho ln thit lpsau. Ch s delay gia cp ngun ch ( s-d ) c o bng s lightpath ( hoc s hop ) tnode sn node d.

Cc k hiu

tsd : L ng traffic cn truyn tngun s n ch d Lold : Topo logic hin hnh

Lnew : Topo logic m i

wneil : lightpath trong topo logic c

old il : lightpath trong topo logic m i

Ga(Va,Ea) : biu phtr

S : dy chuyn tip 1 2{ , , , }nS l l l= K v i wi nel L

iT : Topo logic sau khi thc hin u tin chuyn tip ti cu hnh th i

( , )iT

H s d : s hop logic nh nht m mt lung traffic phi v t qua khitruyn ts n d trn topo logic Ti

( ) N l : tp h p cc lightpath c m c xungt v i lightpathl

( )S : shop trung bnh ca dy chuyn tip. ( , )

( ) .isd T

s d

sd s d

t H s d

S n t =


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Thut ton tm hm thch nghi

Thng s u vo : Lold , Lnew, tsd , 1 2{ , , , }nS l l l= K

Thng s u ra : ( )S

Cc b c thc hin

B c 1 : T=Lold . Tnh ma trn HT dng thut ton tm ng i ngn nht Ford

B c 2 : Tnh shop logic m lung traffic v t qua tnode sn node d. ( , )

ia sd T s d

H t H s d =

B c 3 : To vng lp cho i chy t1 n n ( v i n l s lightpath m i xungtv i lightpath c ). Thc hin ln l t theo trnh tsau

v t[ ]SC i

l l= , cng lightpathl vo topo hin hnhT , xa ( remove )( ) N l cc lightpath c m c xungt v i lightpathl

v Dng thut ton tm ngi ngn nht tnh li HT v Tnh li shop logic . ( , )a a sd T

s d

H H t H s d = +

B c 4 : Trvgi tr ( )S

( ).

a

sd s d

H S

n t =


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Thut ton Ford tm ma trn hop logic H

Thut ton Ford l thut ton tm ngi ngn nht tn node ngun n n nodech

Hnh 3.2 : S thut ton Ford


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Ch ng 4 : Thut ton di truyn GA


CH NG 4THUT TON DI TRUYN GA

( GENERIC ALGORITHM )

4.1. Gi i thiu vGATrong sinh hot hng ngy, th ng gp rt nhiu vn , t n gin n phc

tp. C nhng vn lin quann sinh hot c nhn, nh vic bmtm ng ingn nht a con n tr ng, nhng cng vic c quan, c th k xp lch biuhng ngy cho gimc, anh cng nhn k thut hoch nh ch ng trnh cho mymc vn hnh v i chi ph v th i gian nh nht m vn m bo nng sut, cht

l ng,C rt nhiu gii php c a ra gii quyt cho cc vn nu trn nhng

khng gii php noem li hiu qucao nht. C nhng vn qu phc tp, khngththy c gii php tr c mt, hay khng gian tm kim qu l n, khng bit phibt u t u.

Trong nhng nm 70, mng n ron nhn to, logic m , cng v i thut ton ditruyn c nghin cu v p dng thnh cng trong vic gii quyt cc tr ng h pphc tp.

Thut ton di truyn c pht minh rabt tr c qu trnh pht trin t nhin trongiu kin quynh sn ca mi tr ng. Ccc im ca qu trnh nythu ht s ch ca John Holand ( i hc Michigan) ngay t nhng nm 1970.Holand tin rng s gn kt thch h p trong thut ton my tnh c th to ra mt k thut gip gii quyt cc vn kh khn ging nh trong tnhin din ra thngqua qu trnh tin ha.

Ngy nay, cng ngh thng tin v ang ng vai tr quan trng trong isng kinh t, x hi ca nhiu quc gia trn thgi i, l mt phn khng ththiu trongmt x hi nng ng, ngy cng hin i ha. V vy, vic tin hc ha vo mt s l nh vcng dng l hon ton c thv ph h p v i xu h ng hin nay.

Xut pht tnhu cu thc t , em p dng thut ton ny voti lunvn ca mnh.y l ch ng trnh tin hc cho php ng i sdng tm ra c kt qu gn ti u nht m nu dng vic tnh ton thng th ng s rt phc tp v tn rtnhiu th i gian. Ch ng trnh ny khng nhm a ra l i gii chnh xc ti u mara l i gii t ngi ti u.

p dng thut ton di truyn vo my tnh l ph ng phpng dng tr tu nhn to vo vic gii quyt cc bi ton phc tp. Thng qua tnh di truyn, s laighp,t bin ngu nhin tnhng c thc cc tnh nng,u im khc nhau. Sau


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nhiu ln chn lc qua nhiu thh, thhcui cng sl ging cy, con vt mongmun. Vn t ra l chi ph thc hin v kt qu t c. Thng th ng kt qu t c t ng i tt, cng c thl tt nht, c bit i v i nhng vn nan gii,cc thut ton thng th ng khng thgii quyt c.

Banu, ta spht sinh mt sl ng l n, gi i hn cc c thc gen ngu nhin ngh a l pht sinh mt tp h p cc chui bit ngu nhin. Tp cc c thny c gil qun thban u (initial population). Sau, da trn mt hm no, ta sxcnh c mt gi tr gi l thch nghi - Fitness. Gi tr ny, n gin c thtmhiu chnh l"tt" ca l i gii haycao trong tm kim theo kiu leoi. V phtsinh ngu nhin nn"tt" ca l i gii hay tnh thch nghi ca cc c thtrong qunthbanu l khng xcnh.

ci thin tnh thch nghi ca qun th, ng i ta tm cch to ra qun thm i.

C hai thao tc thc hin trn thhhin ti to ra mt thhkhc v i thchnghi tt h n.

Thao tcu tin l sao chp nguyn mu mt nhm cc c th tt t thh tr c ri a sang thhsau (selection). Thao tc nym bo thch nghi ca th hsau lun c gi mt mc h p l. Cc c th c chn thng th ng l ccc thc thch nghi cao nht.

Thao tc thhai l to cc c thm i bng cch thc hin cc thao tc sinh sntrn mt sc th c chn t thhtr c thng th ng cng l nhng c thc

thch nghi cao. C hai loi thao tc sinh sn : mt l lai to (crossover), hai ltbin (mutation). Trong thao tc lai to, tgen ca hai c th c chn trong thh tr c s c phi h p v i nhau (theo mt squy tc no) to thnh hai gen m i.

Thao tc chn lc v lai to gip to ra thhsau. Tuy nhin, nhiu khi do th hkh i to banu cc tnh cha phong ph v cha ph h p nn cc c thkhngri u c ht khng gian ca bi ton . T , kh c thtm ra l i gii ti u chobi ton. Thao tct bin sgip gii quyt c vn ny. l sbin i ngunhin mt hoc nhiu thnh phn gen ca mt c th thhtr c to ra mt c th hon ton m i ththsau. Nhng thao tc ny ch c php xy ra v i tn sut rtthp (th ng d i 0.1), v thao tc ny c thgy xo trn v lm mt i nhng c th chn lc v lai to c tnh thch nghi cao, dn n thut ton khng cn hiu qu.

Thhm i c to ra li c x l nh thhtr c (xcnh thch nghiv to thhm i) chon khi c mt c th t c gii php mong mun hoc tn th i gian gi i hn.


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4.2. Cu trc ca thut ton di truynTrong GA, cc c th(hay cn gi l nhim sc thvit tt l NST) c m

ha b i cc chui nh phn, mi v tr trn chui nh phn ch nhn mt trong hai gitr 1 hoc 0. Mt NST trong GA c in c dng nhsau:

0 0 0 1 1 1 0 1 0

Mi kiu gen (mt NST c th) biu th mt l i gii c thca bi ton; mtqu trnh tin ha c thc hin trn mt qun th(mt tp h p NST) t ng ngv i s tm kim trong mt khng gian cc l i gii c th. S tm kim nyi hi c

scn bng gia hai mc ch: tm l i gii tt nht v khm ph khng gian tm kim.Thut ton di truyn c in tm kim theo nhiu h ng bng cch duy tr mt tp l igii c th, khuyn khch shnh thnh v traoi thng tin gia cc h ng. Tp h pcc l i gii tri qua cc qu trnh tin ha v cui cng cho ta mt tp h p cc l i giitt ty theo yu cu. Ti mi thh, cc l i gii t ng i tt c ti sinh, trong cc l i gii t ng i ti b loi b. phn bit gia cc l i gii khc nhau, ng ita dng mt hm gi l hm thch nghi nh gitt, xu ca tng l i gii, hm

nyng vai tr ca mt mi tr ng sng trong thuyt tin ha.GA c in c J. H Holland gi i thiu gii bi ton ti u: max {f(x) / x

M}, trong M l mt min trong khng gian n-chiu, f(x) > 0 v i mi x M. Cutrc ca GA c in nhsau:


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Procedure GABegin

T = 0Kh i to P(t)

nh gi P(t)While ( not(iu kin dng )) doBegin

T = T + 1Chn P(t) tP(t-1)Thayi P(t)nh gi P(t)

EndEnd.

Cc qu trnh tin ha c din ra trong vng lp While, ti thhth t, thutton duy tr mt tp l i gii P(t) = {xt1, , xtn}. Mi l i gii xti c nh gi thch nghi. Mt tp l i gii m i c xy dng bng cch chn lc cc c ththch

nghi h n, ta c mt tp l i gii trung gian. Tip theo, mt sc thtrong tp l i giiny c bin i bng ph ng php lai ghp v t bin to thnh cc l i giim i cho thht + 1.

Hnh 4.1 : V d minh h a thu t ton v ton t di truy n


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Trong v dminh ha bng hnh 9.18, ta thy ti thhthn ta c mt l i gii cthch nghi rt thp (2), v v vy, n khng c sdng trong qu trnh ti snxut. Thay vo, l i gii c thch nghi cao nht (13) s c nhni vavo qu trnh ti sn xut.

4.3. Cc tnh cht c th ca thut ton di truyn GA lp lun mang tnh cht ngu nhin, thay v xcnh nh ton hc gii

tch.

GA duyt xt ton bcc gii php, sau chn ly gii php t ngi ttnht da trn hsthch nghi.

GA khng n chi tit vn , tri li ch ch n gii php,c bitl dy st ng trng cho gii php.

GA rt thch h p cho vic tm kim gii p cc vn , hay tmiu kinti u cho vic iu hnh, v phn nhm nhng gii php c c.

4.4. Cc b c quan trng trong vic p dng thut ton di truyngii quyt vn (bi ton) bng thut ton di truyn, chng ta cn thc

hin by b c quan trng sauy:

- B c 1: chn m hnh cho gii php ca vn : chn mt st ng trng choton bcc gii php (qun th) c thc cho vn .

- B c 2: ch nh cho mi gii php (c th) mt k hiu. K hiu c th lmt dy cc s0, 1 thuc hnh phn, hay dy cc sthp phn, dy cc chhayhn h p ca sv ch. K hiu n gin nht v th ng dng nht l dy cc s nh phn 0, 1.

- B c 3: tm hm s thch nghi cho vn v tnh hs thch nghi cho tnggii php (l i gii)

- B c 4: da trn hs thch nghi ca cc gii phpthc hin s to sinh(reproduction) v bin ha cc gii php. Cc ph ng thc bin ha bao gm: laighp (crossover),t bin (mutation).

- B c 5: tnh cc hs thch nghi cho cc gii php m i v loi bnhng giiphp km nht ch cn gi li mt snht nh cc gii php.

- B c 6: nu cha tm c gii php ti u hay t ng i kh nht hay chaht k hnn nh, tr li b c tht tm gii php m i.

- B c 7: tm c gii php ti u hoc nu th i gian cho php chm dtth kt thc thut ton v bo co kt qutm c.


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Hnh 4.2 : S thut ton di truy n

4.5. Cc php ton v cc thng sca GA4.5.1 Cc php ton

4.5.1.a. Php chn lc

Php chn lc l mt qu trnh trong c th c chn tham gia vocc pha tip theo ca qu trnh tin ha. Vic chn la ny ty thuc vo thch nghi ca c th , ngh a l nhng c thno c gi tr hm thch nghi caoh n sc khnng c nhiu con chu trong thhtip theo. Php chn lc cth c biu din d i dng mt bnh xe x sRoulettle, l mt hnh trntrong mi c thtrong thhhin hnh chim mt phn t ngng v i gi tr ca hm thch nghi ca n. Cc gi tr ny chnh l xc sut chn lc ca mi cth, c tnh theo cng thc:

pi = f(vi) / F

Trong: f(vi) l gi tr ca hm thch nghi ca mi c thvi.

F l tng ca cc gi tr thch nghi ca qun th.


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Hnh 4.3 sauy minh ha bnh xe xsca qu trnh la chn. Trong hnh, cth1 c xc sut chn lc l 25%, mi ln quay bnh xe x sn c khnng c chn l 0.25. T ng tnhvy i v i cc c th2, 3, 4.

Hnh 4.3 : Bnh xe x s m t qu trnh l a ch n

4.5.1.b. Php lai ghp ( traoi cho )

Php traoi cho hay cn gi l php lai ghp, kt h p ccc tnh trnNST ca bv m to thnh hai c thm i, bng cch troi ccon gen.

V d: ChaM

Th vic traoi cho cc NST sau gen th5 sto ra hai con:1 0 1 1 0 1 0 1 0

0 0 0 1 1 1 1 0 0

4.5.1.c. Phpt bin

Skt h p ca cc php chn lc v lai to i khi lm tht nhng NST ctim nng. Phpt bin c t ra nhm khc phc thiu st trn.

Phpt bin l ssa i mt vi gen ca mt NST c chn, bng cchthayi ngu nhin v i xc sut l t l t bin.

V d:

1 0 1 1 0 1 0 1 0

1 0 1 1 1 1 0 1 0

V1

V2

25%1

37.5%2

20%3

15%4

1 0 1 1 0 1 1 0 0

0 0 0 1 1 1 0 1 0

Con 1

Con 2


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NST V1 c chn t bin ti v tr gen thnm, gen ny hin ti l 0,sau khit bin str thnh 1. Khi NST V1 tr thnh V2.

4.5.2. Cc thng sca thut ton di truyn4.5.2.a. Kch th c qun th( Population size )

Kch th c qun thchnh l s l ng NST trong qun th( tnh trong mtthh). Nu sl ng NST l qu t th bng php lai ghp sci thin s l ngNST. Trong tr ng h p s l ng NST t th chng ta ch kho st mt phn nh trong khng gian tm kim, ng c li nu sl ng NST qu l n th th i gian x l ca thut gii di truyn ti mi thhschm. Theo thc nghim, kch th cqun thc gi tr t vi chc n vi trm. Kch th c qun thskhngiqua tng thh

4.5.2.b. Xc sut lai ghp Pc

Khng phi bt k NST no sau khi qua chn lc cng c lai ghp. Laighp ch thc hin v i mt xc sut nhh n 1. Xc sut lai ghp biu din mcxy ra th ng xuynthc hin vic lai ghp. Nu khng c php lai ghpth c thcon c chn ra chnh l bn sao tc thcha m, trong tr ng h pny th khng phi qun thm i hon ton ging v i qun th tr c v cnphi phthuc vo cch chn NSTtin hnh sao chp. Nu xc sut lai ghpl 1 th ton bcc c thcon c to ra bng php lai ghp.

4.5.2.c. Xc sut t bin Pm t bin ch c thc hin v i mt xc sut rt thp ( th ng nhh n 0.1 ).

Xc sut t bin biu din mc xy ra th ng xuyn ca NST b t binti gen. Nu khng c s t bin th cc c th c chn skhng c s thayi no tr nh h ng ca php lai.

4.6. Cc ton t ca thut ton di truyn4.6.1. Ton t chn lc c th

Ton t chn lc c th l thao tc x l trong mi c th c bo lu chovng to sinh tip sau ty thuc vo gi tr thch nghi ca n. Ton tny ging nh qu trnh chn lc tnhin. Gi tr thch nghi f(i) l cc gi tr c tnh ton xcnhv gn cho mi NST (f(i) l gi tr thch nghi gn cho NST th i), nu NST c gi tr thch nghi cng l n th khnng c la chn ca n cng l n v NST cng c coil h p l. Hm thch nghi l mt hm bt k c thkhng lin tc, d ng hay phituyn.

C nhiu ph ng php chn lc c th nh: Chn bng bnh xe Roulettle

( Roulettle wheel selection ), la chn bng ph ng php bng phu ng php xp hng( Rank selection ).


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4.6.1.a. Ph ng php chn lc bnh xe Roulettle

X l chn lc c thcha m c chn ra theo m hnh ti sinh trn vngtrn Roulttle ( Roulttle wheel ). Vng quay ca c kch c khc nhaung v inhng gi tr h p l ca tng c th. K thut ny gi l la chn cha m trn

vng quay ( Roulttle wheel parent selection ). Mi khi cn ti sinh mt c th con m i th ch cn quay vng trn vng trn Roulttlechn ra c nhng cthcha msang gi ra lmng cvin cho vic ti sinh m i.

thc hin k thut ny ta theo cc b c sau:

v [Sum] Tnh tng tt ccc gi tr thch nghi ca c thtrong qun thgil tng thch ngi ( total fitness ).

v [Select] Ly ngu nhin mt s r c gi tr trong khon t 0 n tngthch nghi.

v [Loop] Chon c mt thnh vinu tin trong qun thc thchnghi bng tng tch ly ca n v i thch nghi ca cc c thtr c nl n h n hoc bng r.

Nh c im ca ph ng php ny l khi gia cc c thc thch nghil n th xc sut c chn ca cc c thc thch nghi nhh n khc l rt t.Chng hn nu trong qun thc mt c thc thch nghi l n h n 90% cc cthkhc th xc sut la chn ca cc c thkhc n l rt thp.

4.6.1.b. Ph ng php chn lc xp hng( Rank selection )Trong cch la chn ny ta xp hng cc c th trong qun th theo th t

v u tin tng dn, v sth tca n trong bng xp hng c gn cho lch s thch nghi ca c th . V d: c thxu nht s ng u danh sch v c gn ch s thch nghi l 1, c thxu ktip ng thhai k v cgn ch sthch nghi l 2, v c thtt nht sc sthtl n v c ch sthchnghi l n ( n chnh l kch th c qun th).

4.6.1.c. Ph ong php chn lc bng trng thi n nh ( Steady stateselection )

Ph ng php la chn bng trng thin nh khng phi l mt ph ngphp cth la chn c thcha m. t ng ca ph ng php ny l hu htcc c th c chn tham gia vo thhktip.

4.6.1.d. Ph ng phpu tranh

Ph ng php ny kh n gin ch l ta la chn ra mt tp nh cc cthtrong qun thv c thno c ch sthch nghi tt nht s c chn lm cthcha m.


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4.6.1.e. Ph ng php Top-Mate

Trong ph ng php ny mt c thcha m c la chn theo trt t thch nghi, cn cc c thcn li c la chn mt cch ngu nhin.

4.6.2. Ton t lai ghpLai ghp nhm nng cao kt quc th, do , ton t lai ghp sto iu kin

cho tin trnh hi tnhanh hay chm. Cn ty thuc vo cch tchc v phn bccnhim sc thm chng ta c xc sut lai ghp nhanh hay chm. Sau y l viph ng php lai ghp thng dng trong k thut di truyn:

4.6.2.a. Lai ti mt im

Nh cp trn ( phn 4.5.1b ), chng ta ct ngu nhin mt v tr trong NST, tin hnh traoi cho cc c thcha mti im ct ny.

Tuy nhin cng vic ny vn cn mt shn chtrong vic tm kim l c. V d : gis ta c hai l c trn trung bnh sau [4]:

S1 = (01******01) v S2 = (****11****)

Trong tp l i gii c hai chui ng v i hai l c trn l:

v1 = (0110011001) v v2 = (1110110100)

R rng, v i hai chui trn, php lai khng thto ra mt chui nong v il c sauy: S3 = (01**11**01), h n na l c thnht sb loi b.

S hn ch th hai i v i php lai c in (p dng mt im traoicho) l: skhngi xng gia php lai v phpt bin. Phpt bin ph thuc vodi ca chui, cn php traoi cho th khng. Tht vy, gis xc sut t bin l pm = 0.01, nu di ca chui l 100 th trong mi chui ckhong mt bt b t bin, cn nu di chui l 1000 th trong mi chui ckhong 10 bt b t bin. Trong khi, trong chai tr ng h p trn, php lai c in vn kt h p hai chui ch ti mt im.

Do nhm loi bcc li c thtrong cc ph ng php ly l c , nngcp tm kim l i gii ti u trong qu trnh tin ha, khc phc shi ts m caGA c in. Trong vi nm gn y, c nhiu cng trnh nghin cu theo nhiuh ng khc nhautm ccha ra cch x l l c tt h n. Sauy ta s xem xt mt strong cc tip cn php traoi cho ( php lai to )

4.6.2.b. Php lai ti haiim

Chn ngu nhin haiim trong mt NST, sau traoi cho ccon gennm gia haiim ca hai NST cha, m nhn c hai NST con.


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V d : v i hai chui v1, v2 v haiim c chn traoi cho l 3 v 7,ta c cc NST con nhsau:

v1 = ( 0 1 1| 0 0 1| 1 0 0 1 )v2 = ( 1 1 1| 0 1 1| 0 1 0 0 )

v1=( 0 1 1| 0 1 1| 1 0 0 1 )v2=( 1 1 1| 0 0 1| 0 1 0 0 )

V i cch traoi cho ny, cho ta chui v1 ph h p v i l c S3 v l cS1 khng b loi b.

4.6.2.c. Php lai ti nhiu im

Mt t ng khc l, nu php lai haiim khng thkt h p to ra mtc thph h p v i mt l c no, th ta c thp dng php lai nhiu im c khng? Ng i ta a ra thnghim ny. Tuy nhin, php lai nhiu imrc ri h n, v phi ni lun phin gia ccon t ngng ca cha, msau khi ct thnh nhiu on v s im ct phi l schn.

4.6.2.d. Php lai t iu chnh phn bcc im bt cho

Hai nh khoa hc Schaffer v Morishima a ra mt th nghim vphplai c khnng t iu chnh phn bca ccim bt cho da vos t n t ica c th thch nghi cao nh t v s ti k t h p . t ng ny c thc hin

bng cch m ha bn bt cho v gn vo biu din chui. Nhng bn ny nh du ccim bt cho khi thc hin cc php lai. Trong qu trnh tinha, nu cch lai to no to ra c thcon cht l ng xu, cch lai to sb loi bv ng c li. Cc th nghim lai to trn cho kt qukhquan h n sov i ph ng php trao lai to c in.

4.6.2.e. Php lai Segmented Crossover

y c thxem l ci tin ca php lai nhiu im. Trong ci tin ny, s im bt cho khng phi l mt sc nh, m l mt t lngt on. T lnyxcnh mt on gen trong chui kt thc ti mt im bt k no.

V d : cho t lngt on s = 0,2; khi kt u mt on, khnng ktthc on ny ca mi bt l 0,2. Hay ta c thhiu rng, s cc im btcho ca chui l m/5 (m ldi chui). Mt skhc bit so v i php lainhiu im l s im bt cho khng phi l c nh.

4.6.2.f. Php laing nht

Php lai ny c th c xem l sm rng ca php lai mt im, hai

im v nhiu im. Ni dung ca php lai ny nh sau: gi p l xc sut mibt trn c thcon thnht ly tc thcha hoc m, bt t ngng trn c th con thhai sly trn c thcha hoc mcn li (v d: nu bt mt ca c th


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con th nht ly bt mt ca c thcha, th bt mt ca con th hai s ly btmt ca m). Sauy l mt v dminh ha:

Cho hai c thcha, mln l t l:

v1 = (0 1 0 0 0 1 1 0 0 1)

v2 = (1 1 0 1 1 0 0 0 1 0)Ta c thc cp c thcon nhsau:

v1 = (01 11 02 01 12 11 02 01 01 02)

v2 = (12 12 01 11 01 12 01 02 12 11)

Cc ch s1 v 2u ch bt l ca v1 hoc v2

V nh giu nh c im ca ph ng php ny, trong mt cng trnh

nghin cu, Spears v De Jong kt lun l: v php lai ng nh t trao itheo bit cho nn n c u i m l t c nguy c ph v cc kh i c bn, nh ngtrong m t s bi ton khc, n l i km hi u quh n php lai hai i m .

4.6.2.g. Php lai nhiu cha m

Hai nh khoa hc Muhlenbein v Voigt a ra mt ton t ti kt h pm i c gi l ti k t h p qu gen , trong cc gen ca mt c thcon cchn mt cch ngu nhin tqugen ca cc c thcha, m c chn. Php lainy cho php mt c thcon c thc nhiu cha, m.

Tm li, trong vi nm gn y, nhiu ci tin ca php traoi cho xuthin. N c khng nh h n hn php traoi cho c in, nhng cha c phpno v t tri h n cc php cng b. Qua thnghim, Eshelman a ra mt ktlun tng qut l: mi loi traoi cho ch thch h p v i mt loi bi ton cthno, iu ny cng khng nh thm t ng vcc thut ton di truyn c cc ton t phthuc bi ton.

4.6.3. Ton t t bin

Cng ging nh lai ghp, ton t t bin lm tng nhanh qu trnh hi t,nhng tng mt ccht ngt, cng c khi skhng gy tc dng g mt khi khngthnh cng. Khng ai c th nh gi c ph ng phpt bin no tt h n, doc mt vi ph ng php n gin, cng c vi tr ng h p kh phc tp. Ng i tath ng chn mt trong nhng ph ng php sau :

4.6.3.a.o bit

Chn ra bit v i xc sut cho tr c, o gi tr ca bit t 0 thnh 1 vng c li


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V d:

1 1 0 1 1 0 0 0 1 0

1 1 1 0 1 0 0 0 1 0

4.6.3.b. Thayi trt t

Hai bit c chn sthayi v tr cho nhau

V d:

1 0 0 1 0 1 0 0 0 1

1 0 1 1 0 0 0 0 0 1

Cc thao tc x l ny c p dng lp li chon khi cc NST con chuca chng tng tr ng t i kch c mong mun ca qun th.

4.6.3.c.t bin o ng cChn hai v tr ngu nhin trong mt nhim sc thv sau, nghch o

chui gia hai v tr ny.V d :

Nhim sc th: 9 3 8 5 7 1 6 4 2Sau khit bin: 9 31 7 5 8 6 4 2

4.6.3.d.t bin chnChn ngu nhin mt gen v sau chn n vo v tr ngu nhin.

V d :

Nhim sc th: 9 38 5 7 1 6 4 2

Saut bin: 9 3 5 78 1 6 4 2


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4.6.3.e. t bin thay th Chn ngu nhin mt chui con v chn n vo mt v tr ngu nhin.t

bin chn c th c xem nhtr ng h p c bit ca t bin thay th, trong, chui con ch cha mt gen.

V d :

Nhim sc th: 9 38 5 7 1 6 4 2

Saut bin: 9 3 68 5 7 1 4 2

4.7. u nh c im v ng dng ca thut ton di truyn

4.7.1. u im u im ca thut ton di truyn l tnh song song ca n. GA trong khng

gian tm kim v i nhiu c thh n ( v v i kiu di truyn h n l kiu hnh ), v vythut ton ny t khi b r i vo cc l i gii ti u cc bnhnhng ph ng php khc.Thut ton di truyn cng dthc hin , chng ta ch phi biu din NST m i giiquyt cc bi ton khc nhau v ny bi ton no c ph ng php m ha NST thchng ta ch cn vit li hm stnhthch nghi cho bi ton m thi.

4.7.2. Nh c imKhuyt im ca thut gii di truyn l th i gian tnh ton ca n, c thl

chm h n so v i cc ph ng php khc, nhng ngy nay v i tc pht trin my

tnh nhv bo th khng cn l vn l n na.4.7.3. ng dng

Thut gii di truyn cng dng cho rt nhiu l nh vc khc nhau

v Trong l nh vc thit k

Ti u ha vic thit kcc bphn cho my bay, tuabin nh my nhitin

v Trong l nh vc tin hc

Tmikin ti u cho vic thit kmng Neutral nhn to.

Thc hin ch ng trnh tin hc c bit IA ( Intelligent Agent ) giph ng dn, cvn ng i sdng trong cc l nh vc gio dc, qun tr,thit v truyn thng.

v Trong l nh vc ha hc

M phng qu trnh chit dung mi.

Tmiu kin cn bng ti u cho ha cht.


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v Trong l nh vc giao thng

Hoch nh l trnh xe ch hang tcc khon cc cng tr ng sao chonhanh v ngn nht.

Hoch nh ch ng trnh trnh bo tr cc xa l.

iu hnh mng l i neon bo hiu ti cc trc giao thng chnh. v Trong ngnh khai thc hm m, du kh

Vn hnh du kh

Tma im khoan du ti i d ng.

Thit kmy bin thcho cc nh myin v Trong xy dng

Qun l cc cng trnh xy dng. v Mt s ng dng khc

Sng tc m nhc

Sp xp th i kha biu


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Ch ng 5 : p dng GA vo bi ton ti cu hnh topo logic


CH NG 5P DNG GA VO BI TON TI CU HNH TOPO LOGIC

5.1. M ha Dng topo ca mt mng N node c th c din tbng ma trn kt ni N x

N, trong mi phn txi,jdin ts ng kt ni tnode in node j [xem 5]

11 12 13 1

21 22 23 2

31 32 33 3

1 2 3

n

n

n

n n n nn

x x x x

x x x x

X x x x x

x x x x

=

LLL

M M M L ML

Trn thc tkhng c d ng kt ni tn n chnh n nn ma trn kt ni lcny l

12 13 1

21 23 2

31 32 3

1 2 3

0

0 0

0

n

n

n

n n n

x x x

x x x X x x x

x x x

=

L

LLM M M L M

L

Ta cng c thtopo ca mng N node d i dng mt vector hng N(N-1) phntnhsau:

X= [x12x13. x1nx23x24. x2n.x(n-1)nx21x31 x32 . xn1 xn2 xn3 . x(n-1)n]

V dmt topo logic ca mt mng 5 node ( hnh d i ) c din td i dngma trn kt ni v chui nh phn t ngng nhsau :


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1

Hnh 5.1 : Topo logic c a mng 5 node

- Ma trn kt ni

0 0 1 1 00 0 1 1 01 0 0 0 10 1 0 0 11 1 0 0 0

L =

- Chui nh phn

1,2 1,3 1,4 1,5 2,3 2,4 2,5 3,4 3,5 4,5 2,1 3,1 3,2 4,1 4,2 4,3 5,1 5,2 5,3 5,4

0 1 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 0

Mi quan hkhi nim ca mng v khi nim ca thut ton di truyn c tm tttrong bng

Khi nim ca GA Khi nim ca mng- Mt c th( individual )- Qun th( population )- Nhim sc th( Chromosome )

- Gen trong nhim sc th

- V tr ca gen trong nhim sc th - Ni dung ca gen

- Mt topo cth - Tp h p nhiu topo- Chui nh phn din tcc kt ni to

nn topo- Bit trong chui nh phn th hin ng ni trong mng

- V tr ng ni trong mng- Sl ng ng ni

B ng 5.1 : So snh cc khi ni m c a m ng v khi ni m c a GA


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5.2. Hm thch nghi (fitness function) Dng nh gi mt c thc tt hay khng. Mt c thcng tt ngh a l

thch nghi ca n cng cao v tin n tr thnh l i gii ng ca bi ton. Vic thitkmt hm thch nghi tt l rt quan trng trong thut ton di truyn. Mt hmnh

gi khng chnh xc c thlm mt i cc c thtt trong qun th.Trong lun vn ny, xy dng hm thch nghi theo cng thc

max

max min. 1 Havg HavgF A Havg Havg

-= +-

V i

A: l mt sd ng, quyt nh binca F

Havg l gi tr hop trung bnh ca mng

Khi Havg = Havgmax = N-1 th F=Fmin=1Khi Havg = Havgmin = 1 th F=Fmax=A+1

Nh phn tch ch ng 3, bi ton ti cu hnh l bi ton ti uu c rngbuc nn trong qu trnh chn lc da vo hm thch nghi c th c nhng c th khng tha iu kin rng buc. C nhiu cchx l tnh hung ny. Cch thngdng nht l dng k thut pht ( penalty technique ).y l ph ng php nhmchuyn bi ton ti u c rng buc sang bi ton ti u khng rng buc bng cchthm hspht vo hm thch nghii v i nhng tr ng h p vi phm iu kin rngbuc.

Mt shm pht th ng c dng nhsau:

5.2.1. Hm pht5.2.1.a. Hm pht t nh

- Dng hscng

1( ) ( )

m

p i ii

f x f x Ca=

= + Trong :

f(x) l hm thch nghi banu ca c thx ,

ia =1 nu rng buc thi vi phm

ia =0 nu rng buc thi thaCi hspht t ngng khi rng buc thi vi phm


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5.4. Tiu chun kt thc iu kin d ng

kt thc vng lp GA, th ng c thch nh tr c s thhcn to ra sau kim tra li thch nghi nhng phn t tt nht bng cch so snh v i bi ton banu.

C cciu kin cho GA theo nhng tiu chun sau :o Theo sthh nh tr co Th i gian chy nh tr co Sau mt khong thhm qua hm thch nghi khng c ci thino Sau mt khong th i gian m qua hm thch nghi khng c ci

thino Mt gi tr thch nghinh tr c

Trong lun vn ny, chn iu kin dng l chy theo sthh nh tr c.

5.5. Cc b c p dng thut ton GA vo bi ton ti cu hnh topo logic5.5.1. Kh i to qun th

To qun thban u bng cch to ngu nhin. Bi ton ti cu hnht ra lp dng cho mng n node, nn to qun thngu nhin n node v i kch th c qun th

xc nh tr c. Tuy nhinrt ngn khng gian tm kim,dng topo logic hin hnhgn vo qun thbanu.

5.5.2. Kim tra iu kin d ngSau khi kh i to qun th, tnh gi tr hop trung bnh v kim traiu kin rng

buc.

Gi tr hop trung bnh c tnh theo cng thc:

.sd sd s d

sd s d

t h Havg

t =

5.5.3. Chn lcMi c th c chn lc da vo gi tr thch nghi ca n. Nu gi tr thch

nghi cng cao th xc sut chn lc cng l n.

Gi tr thch nghi ca mi c th c tnh theo cng thc

max

max min. 1 Havg HavgF A Havg Havg

-= +-


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Chn lc theo bnh xe Routtle v i cc rnh c nh kch th c theothchnghi.

Qu trnh xy dng bnh xe Routtleo Tnhthch nghi eval(Ni) ca mi nhim sc thNi ( i=1...pop_size)o Tm tng gi tr thch nghi ton qun th

1( )

popsize

i

Tong eval Ni=

=

o Tnh xc sut chn pi cho mi nhim sc thNi:

p i = eval(Ni)/Tong

o Tnh v tr xc sut qi cho mi nhim sc thNi:

1

i

i j j

q p=

= Tin trnh chn lc bng cch quay bnh xe Routtle popsize ln, mi ln chn

mt nhim sc ththeo cch sau:o Pht sinh ngu nhin mt sr trong khong [0..1]

o Nu r


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5.5.5. t bint bin o bit : v i xc sut t bin pm.

V i mi bt trn mt NST ca tp l i gii:

o Sinh mt sngu nhin r [0, 1].o Nu r < pm ta o bt (i 1 thnh 0 v ng c li).


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Ch ng 6 : Kt qum phng


6.1.2. Bi ton reconfiguration

- Dliu u vo:

o Topo logic va m i thit k o Thayi traffic v i traffic m i l

2

0 2 18 50 243 0 32 51 302 10 0 16 221 1 7 0 2823 3 9 20 0

T =

o Slightpath thayi: NoChange

- iu kin rng buc:o Sport ti mi node : TRmax = 2o Shop logic ti a : Hopmax=3o Slightpath thayi so v i topo logic c: NoC


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- Topo logic

Hnh 6.2 : Topo logic c xy d ng t T 2 b ng ph ng php new-design method

- Gi tr hop trung bnh : H2 = 1.323863

So snh gi tr hop trung bnh nhn thy rng ph ng phpnew-design method c gi tr nhh n nhiu ( H2 = 1.323863 ) so v i ( H1 = 1.53125 ). Tuy nhin nu sosnh s lightpath thayi hnh 6.1 v hnh 6.2 ta thy c 5 lightpath b xa v 5lightpath c cng vo. Do tng s lightpath thayi khi chuyn t trng thihin hnh ( hnh 6.1 )n trng thi m i ( hnh 6.2 ) l rt l n ( NoChange =10 ) phimt nhiu th i gian chuyn i v c thlm tht thot traffic.

Do bi tont ra tm topo m i sao cho s lightpath thayi t h n so v iph ng phpnew-design method trong khi gi tr hop trung bnh c thchp nhn c.

V i cng mt kch th c qun thl 200, s thhl 200. Tin hnh thayislightpath cho php thayi

Ln chy thnht: v i slightpath cho php thayi ti a l 4.

Kt qu - NoChange=4:- Ma trn kt ni

2,4

0 0 1 1 01 0 1 0 00 1 0 0 10 1 0 0 1

1 0 0 1 0

L =


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- Topo logic

Hn

giai bai toan tai cau hinh topo logic bang ga

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