1.1 M hnh trin khai thit b spliter trong mng ODN (GPON)1.1.1 Nguyn tc chung: Lp t ti a 2 cp b chia/ghp quang th ng (Spliter). Vic lp t b chia phi tnh ti vn suy hao m bo khi lp thit b vo h thng hot ng c theo ng nh tnh ton. Tng chiu di tuyn cp quang t OLT n ONU/ONT khng qu 20 km. Suy hao ti a trong mng quang th ng GPON khng qu 28dB (tnh t OLT n ONU/ONT). Suy hao quang ph thuc vo nhiu yu t nh u ni quang, u ni tch cc, u ni c kh, suy hao si quang, suy hao b chia quang vv. y ch xt 3 tham s lin quan n suy hao l suy hao connector, suy hao si quang bao gm c cc mi hn v suy hao b chia quang (xem bng di).M tSuy hao (dB)

Suy hao s quang0.35dB/km

Suy hao mi hn0.1dB/mi hn

Suy hao connector0.3dB/connector

D phng1~3dB

Suy hao ca spliter hng VissemT l chia ca SpliterSuy hao (dB)

1:2 4 dB

1:4 7.4 dB

1:8 10.7 dB

1:16 14 dB

1:32 17.2 dB

1:64 21.5 dB

Suy hao ca spliter hng KexinT l chia ca SpliterSuy hao (dB)

1:2 3.5 dB

1:4 7.5 dB

1:8 10.5 dB

1:16 13.5 dB

1:32 17.5 dB

1:64 20.5 dB

Ch : Trong vic thit k, khi t 1 b chia (spliter) vo h thng, cho d cha dng ht s cng ca spliter nhng gi tr suy hao vn tnh bng gi tr suy hao tng ca spliter , v d spliter 1:64 l 19.7dB

Tng suy hao (dB)= Suy hao si quang x (chiu di cp quang) +Suy hao ca spliter +Suy hao mi hn x (tng s mi hn) +Suy hao connector x (tng s connector) + D phng

Hnh 1: M hnh lp t spliter trong mng ODN

1.1.1 La chn spliter v gii php lp t:Cn c s lng thu bao d bo, v tr lp t la chn chng loi, dung lng v gii php lp t ph hp: Cc Spliter s c t ti im truy nhp quang (AP = Access Point), im phi quang (t ODF, cc t phi quang DP = Distribution Point) v khng cn cp ngun. Dung lng chia/ghp bao gm: 1:2, 1:4, 1:8, 1:16, 1:32, 1:64. Vic t spliter phi tnh ton m bo ti a khng qu 64 cng quang cung cp ti khch hng trn 1 cng GPON ca OLT.

a. Gii php lp t Splitter 1 cp.- Lp t Splitter 1 cp khi ti khu vc lp t c s thu bao d bo nh sau: [32 < S lng thu bao d bo 64]. Vi gii php ny, cng sut quang ch b chia tch mt ln, tt c cc dch v ca Khch hng c truyn ti thng qua duy nht mt Splitter. Hnh 2: Cu trc lp t Splitter 1 cp

+ Dung lng la chn: 1:16, 1:32 v 1:64.+ V tr lp t: trin khai ti cc im phi quang (DP) hoc im truy nhp quang (AP) v u tin khai ti cc khu vc c mt thu bao cao, ti thiu khong cch ko cp quang thu bao n nh khch hng.

b. Gii php lp t Splitter 2 cp.- Gii php ny c nhiu u im, h s suy hao nh, thun li trong vic kim tra v bo dng mng cp quang, cu hnh cp quang linh hot v c th trin khai trong khu vc rng nh khu thng mi cng nh khu vc thu bao khng tp trung. Vi gii php ny, cng sut quang b chia tch hai ln, tt c cc dch v ca Khch hng c truyn ti thng qua hai cp Splitter.- Tu thuc vo s lng thu bao ti mi khu vc, c im a hnh la chn cu trc, dung lng v chng loi Splitter ph hp sao cho tng s thu bao/cng PON trn OLT 64, thng thng, cc cp Splitter c la chn nh sau: Spliter cp 1 (thng trin khai loi 1:2, 1:4, 1:8) trong loi 1:2 v 1:4 u tin trin khai ngay trong trm vin thng t OLT, cc spliter 1:2, 1:4 s lp t vo trong t phi quang ODF. Spliter 1:8 s trin khai ti cc im phi quang (DP) th nht chia ra cc hng cp quang phn b khc nhau. Spliter cp 2 (1:16, 1:32, 1:64) trin khai ti cc im phi quang (DP) hoc im truy nhp quang (AP) v u tin khai ti cc khu vc c mt thu bao cao, ti thiu khong cch ko cp quang thu bao n nh khch hng.

V d: Splitter cp l loi 1:2 th Splitter cp 2 l loi 1:32; hoc nu Splitter cp 1 l loi 1:4 th Splitter cp 2 l loi 1:16.

Splitter cp 11:4Splitter cp 21:16Splitter cp 11:16OLT Hnh 3: Cu trc lp t Splitter 2 cp

Vic lp t cc spliter vo tng loi t (ODF, DP, AP ) c hng dn c th theo sn phm ca tng hng. Thng s k thut i vi cc spliter chi tit nh trong ph lc 1 (km theo)

1.2 Trin khai mng ODN phn cp thu bao1.2.1 Cp quang thu bao i vi cc tuyn cp thu bao si quang ko ngm: s dng cp thu bao si quang 2Fo loi ng m lng lp t, u ni v cung cp dch v FTTH-AON/GPON. - Khng s dng hp ODF dung lng 4Fo lp t ti nh khch hng.1.2.2 u ni fast connector ng dng: S dng u ni fast connector loi SC/UPC gn vi 2 u cp thu bao si quang 2Fo loi m cht (ti hp ODF In/Outdoor v hp ATB) u ni, cung cp dch v cho khch hng. Phng php lp t nh sau:+ i vi thu bao AON: si quang c lun trong ng bo v si quang (Protective Tube) ng knh 900m gn vo fast connector. Cp thu bao si quang 2Fo c lp c nh, chc chn trong hp ODF v hp ATB, m bo trnh t gy si quang. Vt t s dng bao gm: cp thu bao si quang 2Fo; 04 ng bo v si quang; 04 u fast connetor SC.+ i vi thu bao GPON: si quang c gn trc tip vi u fast connector hoc c th c lun trong ng bo v si quang (Protective Tube) ng knh 900m gn vo fast connector ty theo fast connector ca hng sn xut. Cp thu bao si quang 2Fo c lp c nh, chc chn trong hp ODF v hp ATB, m bo trnh t gy si quang. Vt t s dng bao gm: cp thu bao si quang 2Fo; 02 ng bo v si quang (ty theo loi fast connector); 02 u fast connetor SC.(chi tit ti hnh v v video gi km) Tiu chun k thut i vi u fast connector:+ Suy hao chn - Insertion Loss: IL < 0,3 dB.+ Suy hao phn hi - Return Loss: RL 50 dB.+ Ph hp vi si quang c ng knh v l 250 m; 900 m v cp thu bao si quang loi [2.0x3.1] mm.+ Cho php tho ra, lp li: ti thiu 05 ln (suy hao p ng YCKT).+ Thao tc n gin, khng cn phi c dng c c bit lp t. Dng c thi cng bao gm: km tut si quang, dao ct si quang (khng s dng my hn si quang).1.2.3 Rp ni quang c kh: ng dng: rp ni quang c kh c s dng trong cc trng hp (khng c my hn si quang), c th:+ ng cu, khi phc tm thi thng tin lin lc cho si quang Ring 2-3 kt ni mng truyn dn TDM, MAN-E; ng truyn kt ni trm BTS/BSC v cc thu bao thuc nhm khch hng VIP1 ca VNPT H Ni.+ u ni khc phc s c t cp thu bao si quang 2Fo ca thu bao FTTH-GPON c chiu di t 300 m tr ln (trng hp b t t 2 im tr ln th phi thay mi cp thu bao si quang). Tiu chun k thut i vi rp ni quang c kh:+ Ph hp ni si quang c ng knh 250 m v 900 m.+ Suy hao chn - Insertion Loss: IL < 0,1 dB.+ Lc gi si quang > 1lb (0.45 kg).+ Hot ng tt ti nhit : 00C n + 800C.+ Cho php tho ra, lp li: ti thiu 05 ln (suy hao p ng YCKT).+ Thao tc n gin, khng cn phi c dng c c bit lp t.Splitter