n 3 Femtocell

MC LCLI NI U6CHNG 1: TNG QUAN V FEMTOCELL71.1.M u.71.2.Khi nim v Femtocell.71.3.Nguyn l hot ng ca Femtocel81.4. Chun ca Femtocell.101.5. ng dng ca Femtocell.131.5.1. D bo th trng131.5.2. Vng mc vi femtocell141.6. Femtocell vi Wifi, Macrocell, Microcell, Picocell.15CHNG 218CC VN CA FEMTOCELL182.1. Hon thin 3G Femtocell.182.2. Nhiu v tuyn v phi hp tn s.182.2.1. Nhiu ng knh ( Cochannel Interference)182.2.2. Nhiu knh k ( Adjacent channel interference).192.2.3 Kt lun:202.3. Qun l Femtocell.202.3.1 Cc tin cho vic trin khai thu bao202.3.2. Cc yu cu qun l Femtocell212.3.3. Tng kt v khuyn ngh212.4. Femtocell v bo mt.222.4.1. Nhn thc thit b Femtocell232.4.2. S y quyn242.4.3. Cp php thut ton242.4.4. Bo v chng gian ln242.4.5. Mng v bo mt Backhaul252.4.6. Bo mt nhn thc im truy nhp Femtocell25CHNG 326CC GII PHP KT NI FEMTOCELL TI MNG LI DI NG263.1. M u.263.2. Kin trc da trn UMTS.263.2.1. Gii php Iub trn IP273.2.2. IU trn IP.283.3. Kin trc da trn gii php UMA/GAN.303.4. Kin trc da trn IMS.32 n 3 Femtocell

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DANH MC T VIT TT2nd GenerationTh h th hai

3nd GenerationTh h th ba

3rd Generation Partnership ProjectD n cng tc th h th ba

3rd Generation Partnership Project 2D n cng tc th h th ba 2

Fourth GenerationTh h th t

Asymmetric Digital Subscriber Lineng dy thu bao s bt i xng

Access Pointim truy cp

Base Station ControllTrm iu khin gc

Base Transceiver StationTrm thu pht di ng

Call Admission CotrollKim sot kt ni nhp hc

Digital Subcriber Line ng dy thu bao s

Femto Access Pointim truy cp Femto

Global System for Mobile CommunicasionsH thng thng tin di ng ton cu

General Packet Radio ServiceDch v v tuyn gi tng hp

High-Speed Uplink Packet AccessCng ngh truy nhp gi ng xung tc cao

Internet PotocolGiao thc Internet

Internet Protocol SecurityBo mt giao thc internet

Internet Key ExchangeTrao i kha Internet

Long Term EvolutionCuc tin ha di lu

Modulation and Coding SchemeH thng m ha v iu ch

Network Address TranslationDch a ch mng

Operation and Maintenance CenterTrung tm bo dung v khai thc

Quality of ServiceCht lng dch v

Radio Access NetworkH thng truy cp v tuyn

RadiofrequencyTn s v tuyn

Subscriber StationTrm thu bao

Trusted Platform ModuleNn tng Mo-dun tin cy

Voice over Internet ProtocolTing ni qua internet

WiMAX femtocell access pointim truy cp WiMAX femtocell

Wireless FidelityDng sng vo cht lng cao

Worldwide Interoperability For Microwave AcccessKh nng tng tc ton cu vi truy nhp viba

DANH MC BNG BIU, TH Hnh 1.1 Femtocell7Hnh 1.2 Nguyn tc hot ng ca Femtocell.8Hnh 1.3 Kin trc Femtocell9Hnh 1.4 Chun ca Femtocell11Hnh 1.5 Thit b Femtocell13Hnh 2.1 Nhiu ng knh19Hnh 2.2 Nhiu knh k20Hnh 3.1 Gii php kt ni Femtocell vi mng li26Hnh 3.2a gii php trn Iub trn IP27Hnh 3.5 B giao thc ca gii php da trn UMA/GAN31Hnh 3.6 Kin trc gii php da trn IMS/SIP32

LI NI U

Tnh cp thit ca ti:Theo thi quen s dng, ngi ta thng k c n trn 90% cc dch v d liu v tuyn c thc hin mi trng trong nh (ti gia nh hoc ni lm vic). Do , vic cung cp vng ph sng trong nh tt khng ch cho dch v thoi m c dch v video v c cc dch v d liu tc cao l cc k quan trng i vi nh cung cp mng v tuyn. Femtocell l mt gii php k thut c k vng gii quyt vn trn v hy vng s c trin khai rng ri vo nm 2012. Femtocell c mt s u im chnh nh sau: Chia s ti. Gim chi ph u t c s h tng. Nng cao cht lng tn hiu Vi s pht trin ca femtocell, mt lng ln lu lng c truyn ti trong cc mng macrocell c chuyn ti h thng femtocell. Femtocell c th cung cp cc dch v vng ti ca macrocell vi chi ph c s h tng cho cc thit b ta nh v backhaul c gim ng k, ko theo vic gim chi ph hot ng v u t. Trong mt mng macrocell duy nht, tn hiu di tn s cao b tn hao ln do hin tng m xuyn tng cc ta nh dn n tc d liu thp v cht lng thoi ti. Femtocell c th cung cp tn hiu v tuyn cht lng tt cho cc thu bao trong khi tit kim tiu hao cng sut ca cc thit b di ng mi trng trong nh. Kt cu ca lun vn: Chng 1: Tng quan v Femtocell.Chng 2 : Cc vn ca Femtocell. Chng 3: Cc gii php kt ni Femtocell ti mng li di ng. KT LUN V HNG PHT TRIN Em xin chn thnh cm n c gio Th.s o L Thu Tho nhit tnh, tn ty gip em hon thnh n ny !

CHNG 1: TNG QUAN V FEMTOCELL1.1.M u. Trong mng thng tin di ng t bo, sng raio c ph nh vo cc trm pht sng BTS. Mi mt BTS s ph mt vng gi l cell (t bo). Nhiu cell c thit k cn k nhau ph sng trn din rng. Chnh v cu trc ny m mng thng tin di ng cn c gi l mng t bo hay mng t ong. Trong mng thng tin di ng t bo truyn thng, chng ta thng nghe nhc n macrocell (t bo v m, c bn knh ph ln tm km), microcell (t bo vi m, c bn knh ph gii hn vi trm mt). Vi s pht trin ca mng thng tin i ng t bo, ngi ta cn thit k cc picocell (vng ph tng t nh mt AP WiFi) tng kh nng ca h thng v tng tc truyn thng.1.2.Khi nim v Femtocell. Gn y, khi nim femtocell mi c ra i.Femtocell l mt trm pht sng nh ca mng thng tin di ng t bo c dng nng cao cht lng dch v v cung cp cc dch v gi tr gia tng phm vi gia nh hay vn phng, cng s. Femtocell c xem nh trm pht sng trong nh (home base station) hay im truy nhp mng t bo ging im truy nhp WiFi. Femtocell l cng kt ni ca mng thng tin di ng t bo t ti nh khch hng. S khc bit ln ca femtocell so vi cc macrocell hay microcell truyn thng l femtocell kt ni vi mng ca nh cung cp dch v thng qua mng c nh bng rng nh DSL hay cp, thay v thng qua mng ring ca nh cung cp dch v di ng

Hnh 1.1 Femtocell Femtocell l mt gii php cho hi t c nh di ng, cung cp kt ni tc cao cho ngi dng trong nh. Nhng tim nng v dch v a phng tin trong tng lai chnh l n by cho vic trin khai femtocell. y l mt gii php thay th cho gii php hi t c nh-di ng UMA (Unlicensed Mobile Access) hin gp khng t kh khn trong vic thu ht ngi dng. S khc bit ln nht gia UMA v femtocell l femtocell s dng cng giao din v tuyn nh mng thng tin di ng thay v dng WiFi. Do vy, ngi dng femtocell khng nht thit phi trang b in thoi dual-mode (c th kt ni vi WiFi v GSM/UMTS). 1.3.Nguyn l hot ng ca Femtocel im truy nhp Femtocell c kt ni bi DSL bng thng rng hoc kt ni IP giao din vi mng GSM hoc UMTS chuyn mch gi v cc mng chuyn mch knh. Femtocell lm vic vi cc thit b chun ph hp vi cc chun giao din tn ti trong mng 2G v 3G. iu ny m bo dch v lin tc v c tnh tng thch cao vi cc mng tn ti v trnh c nhng yu cu v tnh thch ng vi cc thit b cm tay. V nguyn tc: Femtocell kt ni ng d liu n cc nh cung cp dch v ca mng di ng thng qua cc ng truyn bng thng rng nh cp ng (DSL) hoc cp quang v thng h tr t hai n nm in thoi di ng trong khu vc . V iu khin: Femtocell kt ni ng iu khin (bo hiu) n cc trm BSC, tng i MSC ca mng di ng v hot ng theo s iu khin ca cc trm ny. Mc ch ca Femtocell l ph sng trong khu vc ca n v c th xem y l mt cng kt ni n mng di ng v l s kt hp gia mng c nh v mng di ng .

Hnh 1.2 Nguyn tc hot ng ca Femtocell. Kin trc Femtocell: Mt trong nhng ch s nh gi mc thnh cng trin khai cng ngh Femtocell l tnh tng hp gia im truy nhp Femto v mng. Nhng yu cu tng hp i hi s pht trin ca cc kin trc thng thng v cc chun cng ngh ph hp m bo ghp ni tng thch cho cc im truy nhp v mng. t c mc tiu ny, din n Femto pht trin mt kin trc c biu din Hnh 3, vi cc thuc tnh tiu chun c nh ngha cho c im truy nhp femto (FAP-Femto Access Point) v cng kt ni Femto (FGW-Femto Gateway). Cc im truy nhp Femto (FAP) gm nhng chc nng in hnh sau: - Qun l bo hiu 3GPP, mt phng ngi s dng, qun l ti nguyn tn s v tuyn - Chc nng vn chuyn IP, qun l QoS, bo mt lp 3, qun l TR-069 - T cu hnh, chc nng tng la, NAT, bo mt.

Hnh 1.3 Kin trc Femtocell Cc cng kt ni Femto (FGW) gm cc chc nng in hnh sau: - 3GPP RANAP, ng b v cung cp nh thi cho mng - Nhn thc v cp php Femtocell, Che du cu trc lin kt AP, mng - Chc nng bo mt IP - Tp hp v nh tuyn lu lng Femtocell, T ng cu hnh Cng vi nhng nh ngha ny, din n Femto v 3GPP vn cn phi tin hnh nhiu cng vic trong thi gian ti c th nh ngha cc kin trc bao gm mt kin trc c s "luh" vi "lucs" v"lups" hng ti CN. Chi tit v nhng yu cu cho Femtocell c xem xt trong bn thuyt mnh ca 3GPP: TS22.001 v hin nay cng nm trong bn mi: TS 22.220.

Cc nh cung cp yu cu cc giao thc v giao tip tiu chun phi c s dng gia im truy nhp Femto v cng kt ni Femto, gia cng kt ni Femto v mng di ng. Trong pht trin di hn, phi m bo tnh tng hp hon ton gia FAP v FGW t tt c cc nh cung cp. t c cn phi tip tc cc hot ng tiu chun ha: - Giao din gia cng kt ni Femto v im truy nhp Femto (bit ti vi tn "luh" trong 3GPP Rel 8) - Cc giao thc bo mt (Rel 9 trong 3GPP) - UICC hoc TPM (trusted platform module) cho thit b nhn thc (FAP) (Rel 9 trong 3GPP) - Qun l cc tnh nng da trn c s TR-069, v qun l cc tiu chun - Trin khai giao din kim tra m trong cng kt ni Femto m bo tnh tng hp trn Fa (luh). C th thy kin trc ny gm hai thnh phn chnh l HNB (a.k.a. Femtocell) v HNB gateway (a.k.a. Femto Gateway). Gia cc thnh phn ny l mt giao din mi Iu-h. Home NodeB (HNB): c kt ni vi mt dch v bng rng gia nh hin c, mt HNB cung cp vng bao ph v tuyn trong mt cn h theo chun ca thit b cm tay 3G. S kt hp cht ch ca cc HNB th kh nng ca mt node B chun cng ging nh mt b iu khin mng v tuyn RNC chun. HNB Gateway (HNB-GW): c ci t trong mng ca nh khai thc, HNB Gateway tp hp lu lng t mt s lng ln cc HNB ri a ln mng li thng qua chun Iu-cs v giao din Iu-ps. Giao din Iu-h: Nm gia HNB v HNB-GW, bao gm mt giao thc ng dng HNB (HNBAP) cho php thun li trong trin khai cc HNB c bit. Giao in ny a ra mt phng php cho vic truyn tn hiu iu khin Iu trn Internet. 1.4. Chun ca Femtocell. T hp ba din n v cng ngh bng rng l 3GPP, Femto v Broadband cng b tiu chun femtocell u tin trn th gii c 3GPP chnh thc xut bn, m ng cho vic chun ho femtocell to ra mt s lng ln, cho php tng thch gia cc cng truy nhp ca cc nh cung cp thit b khc nhau v cc cng kt ni femto (femto gateway). Tiu chun femtocell l mt phn ca tiu chun 3GPP phin bn 8, hon ton c lp vi phn m rng TR-069 (Technical Report-069) ca din n Broadband.

Hnh 1.4 Chun ca FemtocellPh hp vi giao din v tuyn 3G cho in thoi di ng . Ph hp vi h thng qun l t xa TR-069. Ph hp vi giao din Iu. Mt im giao din mi gia femtocell v gateway femtocell c gi l Iu-h. Chun femtocell bao gm bn phn chnh: cu trc mng, cc giao din v can nhiu v tuyn, qun l, d liu v an ninh cho femtocell.V mt cu trc mng, giao din ch yu gia hng triu femtocell tim nng v cc gateway trong li mng c gi l Iuh. Vic s dng li cc giao thc 3GPP UMTS sn c v m rng chng nhm mc ch h tr cc nhu cu trin khai femtocell s lng ln. Chun mi chp nhn giao thc qun l TR-069 ca din n Broadband, c m rng hp thnh mt m hnh d liu mi cho femtocell v c cng tc pht trin bi cc thnh vin ca hai din n Femto v Broadband. Kt qu l din n Broadband xut bn thnh TR-196 (Technical Report 196). TR-069 thc s c s dng rng ri trong cc mng c nh bng rng v cc thit b chuyn i (set-top box) v s cho php cc nh khai thc di ng trin khai h thng mt cch n gin v c th d liu, chn on v cp nht phn mm t ng t xa. Chun mi cng s dng kt hp cc gii php an ninh bao gm cc giao thc IKEv2 (Internet Key Exchange v2) v Ipsec (IP Security) xc nhn nh khai thc v thu bao nhm t c mt s bo m bo mt trong qu trnh trao i d liu. Da vo thnh cng cng ngh femtocell hp nht theo chun 3GPP phin bn 9, hng n LTE femtocell cng nh h tr chc nng tin tin hn cho femtocell 3G. Tiu chun femtocell cng ang c pht trin cho cc cng ngh giao din v tuyn b sung ph hp vi cc nhm cng ngh khc.

Trong Rel-8, 3GPP c nh ngha l cch thc c bn cho s pht trin ca HNB (Home NodeB) v HeNB (Home eNodeB). Nhng yu cu c ngh trong TS 22.011. Trong Rel-9 cng cp n nhng yu cu t Rel-8 v nhng yu cu cho HNB v HeNB trong TS22.220. TR23.832 cp lin trc IMS cho HNB (HNB v HNB Gateway) nh 1 dung lng ty ca HB, v d nh mt ngi khai thc mng offload CS n IMS. T Rel-8, mt c trng quan trng c gi l CSG( Closed Subscriber Group) c gii thiu. HNB cung cp cho nhng ngi dng truy cp b gii hn, ph thuc vo CSG. 1 hoc nhiu t bo thnh t bo CSG, c nhn dng bi s nhn dng s c nht, gi l CSG Identify. N c m t trong TS25.367. TS22.220 : Service requirements for HNB and HeNB TR23.830 : Architecture aspects of HNB and HeNB TR23.832 : IMS aspects of architecture for HNB TS25.467 : UTRAN architecture for 3G HNB TS25.367 : Mobility procedures for Home Node B (HNB) TS25.469 : UTRAN Iuh interface HNB Application Part (HNBAP) signalling TR25.820 : 3G Home Node B (HNB) study item TR25.967 : FDD Home Node B (HNB) RF Requirements TS32.581 : HNB OAM&P, Concepts and requirements for Type 1 interface HNB to HNB Management System TS32.582 : HNB OAM&P, Information model for Type 1 interface HNB to HNB Management System TS32.583 : HNB OAM&P, Procedure flows for Type 1 interface HNB to HNB Management System TR32.821 : Study of Self-Organizing Networks (SON) related OAM Interfaces for Home HNB TR33.820 : Security of HNB/HeNB TS25468 : UTRAN Iuh Interface RANAP User Adaptation (RUA) signaling

Hnh 1.5 Thit b Femtocell1.5. ng dng ca Femtocell. Li ch m cng ngh ha hn mang n cho ngi dng : Gim chi ph gi in thoi di ng ti nh. C mt kt ni tt, cht lng dch v tt hn, tc cao hn Tit kim nng lng tiu tn Cui thng ch cn chi tr mt ha n duy nht cho c in thoi c nh v di ng Nhiu ngi cng dng chung mt femtocell 1.5.1. D bo th trng Theo nghin cu gn y ca ABI Research th n ht nm 2011 s c hn 70 triu femtocell c bn ra th trng v cung cp dch v cho 150 triu ngi. Con s ny tng ng vi mt phn ba doanh thu ca th trng Wi-Fi, tc tm 2 t la. Cn theo mt d bo ca cng ty t vn OVUM th ring Ty u, tnh n 2011 s c khong 11 triu femtocells c ci t. Theo mt thng k c cng b rng ri, c hn 30% cuc gi di ng c thc hin khi ngi dng ang nh. Tip theo, mt bo co gn y ca McKinsey ch ra rng hn 35% ngi dng dch v TV di ng (mobile TV) khi h ang ti nh. Nh vy, r rng cc nh cung cp dch v c l khi h quyt nh u t vo femtocell thc s cung cp dch v a phng tin tc cao. Th trng femtocell ang dn nng ln v hu nh nhiu cng ty sn xut thit b, nhiu nh cung cp mng cng khng mun b l phn bnh ca mnh. Danh sch ny ngy cng di ra. Nh sn xut thit b Netgear v Nokia thng bo s phi hp cho ra i nhng b nh tuyn tt c trong mt tch hp femtocell v c Wi-Fi. Orange v Vodafone cng khng nh h gi RFP (request for proposal) t gia nm 2007 bit rng h vn ang thng mi loi hnh in thoi Unik. G khng l Google cng u t 25 triu la cho cng ty sn xut thit b Ubiquisys sn xut cc trm pht sng ti gia femtocell. V pha Motorola mi chun b gn nh hon tt. Nhng th nghim femtocell vi mng 3G vi nhiu nh cung cp mng Chu u cho nhng kt qu nh mong i. Motorola cng tin hnh th nghim vi Softbank Nht. Huawei cng th nghim femtocell vi Telefonica O2 Ty Ban Nha v Anh quc. Alcatel-Lucent k hp ng vi Sagem cng nhau sn xut v thng mi ha cc ang-ten femtocell. Ericsson th cho bit h nhn c nhng n t hng v femtocell nhng l femtocell cho 2G. Bouygues Telecom (nh cung cp mng ca Php) chn gii php ca Nokia Siemens Networks ci tin vng ph sng GSM cho thu bao ca Bouygues bn trong cc to nh, trong cc cng ty, di tng hm v xung quanh cc trm pht sng Wi-Fi. M, Sprint Nextel l ngi u tin thng mi ha femtocell. H trin khai femtocell cho ngi dng Denver v Indianapolis. Chc chn Sprint Nextel s tip tc m rng vic trin khai femtocell trong nm nay. Thit b femtocell ca h c cung cp bi Samsung, c bn vi gi 50 la cho khch hng. i vi ngi dng n l, h ch phi tr thm 15 la hng thng dng in thoi khng gii hn. Nu ngi dng femtocell cho quy m gia nh (2-5 ngi) th h phi tr 30 la/thng. Theo mt nghin cu ca IMS Research, sau nhiu ln th nghim, femtocell s c bt u trin khai Chu u trong nm nay 2008. Nhm chuyn gia IMS Research cng c cc rng hoc Orange hoc Tele2 s l ngi u tin m cch cng ca th trng mi ny Chu u. Tuy nhin, Idate li c mt kin khc. Idate cho rng vic trin khai femtocell cho mng 3G UMTS trong nm 2008 s rt hn ch v cc chun cho gii php ny cha sn sng cng nh vic tch hp femtocell vo mng c nh s gp khng t kh khn. Do vy, theo h th th trng femtocell s ch c th khi sc 2009 hoc 2010. Cng theo Idate, nhng nh cung cp mng u tin trin khai femtocell Chu u s l Telefonica O2, T-Mobile v Vodafone. 1.5.2. Vng mc vi femtocell Theo mt bo co ca Analysys, d cho v b ngoi li cun ca Femtocell, cng ngh ny vn n cha nhiu vn nghim trng cng nh nhiu him ha. Femtocell, theo nhiu chuyn gia, vn cha t c chn cng ngh, nht l cc vn v phn cp tn s, nhiu gy ra gia femtocell v macrocell hay cc femtocell ln cn. V Femtocell s c lp t gn ging nh Wi-Fi nn nh cung cp hu nh khng th iu chnh v tr ca femtocell hn ch nhiu. Ngoi ra, vn cht lng dch v khi tch hp vi mng c nh s khng tht d dng khi cc nh cung cp dch v di ng li nhm nhe ly i mt phn th trng mng Wi-Fi ca h. Hin ti vn cha c mt chun thng nht hay mt kin trc mng thng nht cho femtocell, iu ny cng s gy khng t kh khn cho vic trin khai chng rng khp. 1.6. Femtocell vi Wifi, Macrocell, Microcell, Picocell. Khng phi macrocell, khng phi microcell, cng khng phi picocell m l mt th trng khc ang ha hn mang li nhiu li ch hp dn mang tn femtocell (FCM).Femtocell l mt cell c vng ph ngang vi picocell (tng ng mt AP ca Wifi) nhng n c km thm cc tnh nng ca mt BSC, MSC. Femtocell cn c coi nh l mt "Home BS" ca 3G. FMC kt hp cc thit b cm tay 3G, cc thit b u cui Wifi vi mt im truy nhp trong nh, im truy cp ny c ni vo mng xDSL ri t xDSL kt ni ti mng li ca nh cung cp dch v. Femtocell to ra mt vng ph trong nh v ang tr thnh i th cnh tranh trc tip vi Wifi. im khc nhau ln nht gia femtocell v Wifi l femtocell dng giao din v tuyn 2G/3G/HSPA v bng tn c cp php ca nh khai thc. Do vy, thit b kt ni c vi femtocells s l cc my cm tay chun ch khng phi cc my cm tay dual-mode (in thoi s dng nhiu hn mt cng ngh cho vic gi cng nh nhn thoi v d liu). Femtocells ha hn mang li nhiu li ch cho ngi dng: gim chi ph gi in thoi di ng ti nh, c kt vi cht lng dch v tt hn v tc cao hn, tit kim nng lng tiu tn, cui thng ch cn chi tr mt ha n duy nht cho c in thoi c nh v di ng, nhiu ngi c th cng dng chung mt femtocell (femtocell hin ti c th h tr ng thi 5-6 kt ni di ng). Cc nh khai thc mng cng c hng rt nhiu li ch t femtocells: C th cnh tranh cng nh gim mi e da t cc dch v VoIP ca nh cung cp dch v Internet.tng cht lng ph sng trong cc cng trnh cng nh tng dung lng v cc dch v gi tr gia tng cho ngi dng, tng doanh thu bnh qun ca mt thu bao/thng, khuyn khch ngi dng s dng 3G hay WiMax, t tng s thu bao 3G, WiMax. Vi nhiu u im vt tri, femtocells ang c th nghim trn ton th gii nhng n cng vp phi nhiu kh khn v th thch.Vodafone v BSNL (n ) hi vng femtocells s lm gim mc gi m ngi tiu dng phi chu. Vivo - nh khai thc vin thng dn u lnh vc ng truyn mt t Brazil, BSNL v c JSC Ukrtelecom ca Ukraine cng biu hin s quan tm ca h ti femtocells. H mong i femtocells s cung cp mt con ng mi pht trin mng v tuyn mc cao hn. Cho n femtocells nng nhit nht c l l nhng hng vin thng mi bt u trin khai 3G, cha c bc tin ln trong kinh doanh 3G. V th, h khng chu bt c rng buc no trong vic quyt nh cng ngh cng nh thit k mng. Thm vo , h mong c s kt hp ca 3G v mng bng rng cung cp c nhiu tin ch hn l ch ring mnh 3G, nhm to ra nhng bc nhy vt theo kp c s h tng ca cc nc pht trin. Nhng hng vin thng ny cho rng s vng mt ca xDSL phm vi rng cn tr h trong vic thm nhp dch v ti tn nh khch hng, tnh mm do ca mng truy nhp v tuyn v sc nng ca femtocells c th ph v gii hn . Cc hng ny t nim tin trn vn vo femtocells v mc tiu ch yu ca h l xy dng femtocells nhanh chng cc thnh ph ln hoc khu vc dn c c thu nhp cao thu c li nhun trong thi gian ngn nht. Ukrtelecom cng ch thng bo v dch v UMTS vi thng trc, v th h tm kim ti femtocell lm tng nhanh s gii thiu cc thit b mi vi mc ch t s ngi s dng ln trong khi ci thin c cht lng dch v. Bt chp tro lu hng ti trm gc mt t t trong nh (femtocells) ang din ra mng m, nhiu hng Vin thng vn hoi nghi v tnh hiu qu ca femtocells. Thm ch Erisson ngi khng l ln nht th gii trong lng Vin thng cn c gng ngn chn tt c cc tro lu hng ti femtocells. Ericsson mun tip tc pht trin v cng c 3G v hi vng 3G vn mang li thu nhp cao m khng cn ti s gip ca femtocell. Orange v Telecom Italia hai nh khai thc vn ng h UMA/dual-mode cng ang lo lng trc tro lu femtocells. Mc d khng mn m lm nhng Telecom Italia thng bo h s sm gii thiu femtocells trong mt tng lai khng xa (UMA l gii php cho php truyn tn hiu qua Internet v kt ni vi mng li di ng, nn vic chuyn sang dng UMA kt ni vi mng li di ng v femtocells l mt vn khng qu kh vi Telecom Italia). Nn kinh t vn pht trin khng ngng v khch hng mun ngy cng c cung cp nhiu dch v hn, c bit l chu u chu lc giu nht th gii. iu ny khin cc nh khai thc phi tip tc u t cho h thng mng ca mnh v femtocells ang l la chn ca nhiu nh khai thc. Femtocells c coi l i th chnh ca Wifi v dual mode (d tnh n nm 2011, doanh thu ca femtocells s bng 1/3 ca Wifi). Nhng cng bng m ni, Femtocells ch c th dnh chin thng vi iu kin gi thnh phi chng. ng Arung Sarin, CEO ca Vodafone khng nh: Gi thnh ca femtocell phi b hn 100$ th n mi c c hi cnh tranh vi Wifi. Nhiu hng vin thng khc thm ch cn cho rng mc gi cn phi thp hn th nhiu. BT cng by t quan im trong bui hi tho v femtocells din ra ti London - ni ni v nh gi ca thit b trm gc t trong nh - Chng ta ang nh gi cho mt cng ngh nhng n vn cn rt t. Gi mt Hub Home ca BT thp hn 50% so vi gi chng ta a ra cho femtocell v vi mc gi ny, chng ta kh c th cnh tranh vi hub. BT l mt trong nhng hng u tin s dng phng php hi t dual-mode trn c s UMA. S ng h ca h dnh cho femtocells mt ln na cng c ngh rng xu th ang chng li dual-mode v ng h femtocell. Khng ch vp phi s hoi nghi ca nhiu nh khai thc, femtocell ang phi hng chu mt go nc lnh trc thi lnh nht ca Texa Instrument mt trong nhng hng sn xut vi mch in t ln nht th gii. Hng ny cho rng, thay v v bo tr cho femtocells h s u t vo nhng cng ngh khc mang tnh thuyt phc hn vi nhiu li ch hn. iu ny l ht sc nghim trng bi nu Texa Instrument ni ring v cc nh sn xut vi mch in t ni chung ng ngoi cuc v gi th trng chip bn ngoi femtocells th cng ngh ny rt kh sng st.CHNG 2CC VN CA FEMTOCELL2.1. Hon thin 3G Femtocell. The Radio Access Network (RAN) : trong UMTS, RAN tng ng BSS trong mng GSM. N lin kt UEs vo mng li. Radio NetworkController (RNC) tng ng BSC trong mng GSM c chc nng iu khin mt vi node B v thc hin qun l ti nguyn v tuyn (RRM) v c kh nng giao tip trc tip vi RNCs khc thng qua giao din Iur. Giao tip RNC vi cc mng li bng mt giao din gi l Iu. RNC thc hin Call Admission Control (CAC) v chp nhn hoc t chi cuc gi ph thuc v nodeB yu cu cuc gi. Femtocell ph sng v tuyn 3G trong nh, cc khu vc cng cng v cc ta nh vn phng. Mi Femtocell h tr 16 ngi dng ti cng mt thi im trong phm vi 600m. Tc ti xung ln ti 22 Mbps v tc ti ln ti 6 Mbps .2.2. Nhiu v tuyn v phi hp tn s. Nhiu l mt vn quan trng trong thng tin di ng, nh hng n cht lng tn hiu, khi x l tn hiu v truyn tn hiu th tn hiu s b mo dng hoc c tp m xen vo trong thit b ti to tn hiu. Femtocell c lp t ti nh ca khch hng, cc ta nh vn phng bng cch s dng lp t bo Marco cellular layery l mt mi trng khng c s qun l cht ch nn nhiu rt d xut hin. 2.2.1. Nhiu ng knh ( Cochannel Interference) Nhiu ng knh l hin tng nhiu do cc ngun pht pht ra tn hiu cng mt tn s hoc cng mt knh pht sng. My thu s thu c c hai tn hiu vi cng khc nhau ty vo v tr v cng sut ca trm pht.

Hnh 2.1 Nhiu ng knh Trong h thng femtocell, nhiu ng knh xy ra do s dng li tn s nhm tng dung lng cho h thng. Khi 1 im truy cp Femtocel qu gn trm macrocell (nh hn 50m),lm cho im truy nhp b gii hn v hiu qu ph sng, bi v mc tn hiu cao nhn c t m ng knh. Khi 1 im truy cp qu xa macrocell, lm cho cc thit b di ng dng trong macrocell khng bt c tn hiu t macro. c trng cho nhiu ng knh l t s C/I( t s sng mang trn nhiu) th hin mi quan h gia cng tn hiu mong mun so vi nhiu ng knh t cc femtocell khc C/I = 10log (Pc/Pi).Yu cu l C/I khong cch cc cell cng tn s phi ln. Nhiu knh k: Cn c 1 b lc tt c th loi b tn s khng mong mun. 2.3. Qun l Femtocell. Qun l giao din v tuyn ca cc Femtocell gn ging vi qun l macrocell thng thng, tuy nhin vi mt s lng ln Femtocell nn cc vn gp phi cng tng ln. 2.3.1 Cc tin cho vic trin khai thu bao im truy nhp Femto s c trin khai ti nh khch hng v mt s mi trng khng kim sot. Bi th cc khch hng c th thc hin mt s hot ng c th nh hng ti hiu nng hot ng ca lp Femtocell m khng thng bo cho nh khai thc. Nhng hnh ng nh vy bao gm: Tho b v thit lp li ngun, ngt kt ni DSL. Di chuyn v tr vt l im truy nhp Femto, thit t li im truy nhp Femto. - S dng cng ng kt ni DSL vi cc ng dng d liu khc. Mt s hnh ng khc gm c tc ng va p vi im truy nhp Femto. 2.3.2. Cc yu cu qun l Femtocell Cc nh cung cp s yu cu cc iu khon v kh nng qun l cc Femtocell, khng mu thun vi cc h thng qun l c s dng cho cc macrocell thng thng. Danh sch nhng yu cu c lit k di y c th hu dng trong vic lp hp ng: Qun l bn kim k (c bit l phn phi l ti khch hng). D liu thit b Femtocell cho cc im truy nhp Femto c nhn hoc tp th. C kh nng nhn bit cc im truy nhp Femto c nhn v kt ni vi khch hng. Kch hot/gii phng thit b Femtocell, c kh nng thit lp hoc ngt truyn dn v tuyn Femtocell, khng ch c bt k iu khin no do khch hng to ra. Qun l cu hnh. Kh nng cu hnh cc thng s v tuyn quan trng nh l nng lng truyn, tn s. Ch rng cng c th cu hnh t ng nhng thng s ny, tuy nhin cc nh cung cp s c cc ty chnh c th khng ch cc tnh hung. Qun l hng hc Cnh bo v thng bo dng nhn bit cc hng hc do ngi s dng tt FAP hoc cc kt ni bng rng. Nhn bit v tr v c kh nng cu hnh li hoc ngt im truy nhp Femto nu nh v tr b thay i. Qun l thay i, bao gm kh nng iu khin nng cp phn mm Kim sot dch v, qun l hiu nng hot ng v dung lng Qun l danh sch cp iu khin truy nhp. Thm na, cc nh cung cp phi c kh nng cu hnh, thay i, v khng ch c nhng thay i ca khch hng. 2.3.3. Tng kt v khuyn ngh Mt h thng qun l y s l mt ch s quan trng nh gi s thnh cng ca vic trin khai Femtocell. N rt quan trng trong vic m bo cht lng dch v tt cho khch hng v trnh c nhng chi ph khng cn thit trong vic qun l v h tr gii php Femtocell. Cc nh khai thc cn c kh nng kim sot, iu khin v nng cp im truy nhp Femto trong nh khch hng. Cc nh cung cp xut gii php TR-069 trn din n bng rng gii quyt vic iu khin nhng yu cu qun l. TR-069 l tp cc giao thc gii quyt nhng yu cu ca cc modem DSL v vic cu hnh ca chng. Tuy nhin, TR-069 khng chi tit ha cc thng s v v tuyn v cu hnh ngi s dng, chng c th yu cu s m rng ca cc tiu chun hin ti hoc cc phng php khc cho vic cu hnh. Hin ti BBF v FF ang lm vic trn mt m hnh chung v s c cp n trong chun 3GPP SA5. xut c a ra l cn c s hp tc trong cng ngh thng qua cc din n Femto, din n Bng rng (thng c bit ti l din n DSL), 3GPP v Lin minh Di ng M (Open Mobile Alliance) nh hng v to iu kin cho s xy dng cc qun l tiu chun cho h thng qun l Femtocell. 2.4. Femtocell v bo mt.Kim sot v tr im truy nhp V cc Femtocell hot ng trong ph v tuyn cho php, nn cc nh khai thc cn phi kim sot v tr Femto hot ng xc nh im truy nhp hot ng trong nc hoc di tn nm ngoi di cho php. H thng qun l Femtocell phi c kh nng ngt hoc ngn s khi to ca im truy nhp nu v tr khng th c xy dng. iu ny yu cu mt kt ni ti h thng qun l trong qu trnh thit b khi to v sau l v tr chnh xc c xc nhn trong qu trnh thit b hot ng. K thut chnh xc

AGPS chnh xc < 100m

Mng Macro sniffing chnh xc < 300m( th)

Cng DSL/ a ch IPPh thuc vo RIR , xc nh khu vc, nc

a ch ci t cung cp cho thu baonh x a ch chnh xc

Khi a Femtocell vo nh cc thu bao s m ra mng di ng vi nhng ri ro mi v cn phi c bo m. Cc khch hng s c truy nhp trc tip ti mt hng mc ca thit b m c kt ni trc tip ti mng di ng. H s c kh nng truy nhp vt l vo phn cng ca cc thnh phn ca thit b v thch ng hoc thay i thit b cho php s dng gian ln gn ging vi khi thc hin vi thit b thu v tinh v cp. Khuyn ngh cc nh khai thc s dng tnh nng O&M phng truy nhp bt hp php vo im truy nhp Femto, bao gm gi mo thng bo, s c mm t ng v thng bo nu cc thnh phn hoc cc thng s quan trng nh l nng lng truyn b tc ng thay i. Cc im truy nhp phi c cng c c v mt vt l v logic, th d cng c h iu hnh (OS), khng c cng m, o c trnh cc d liu nhy cm n h thng ng truyn dn v b nh ca thit b, ngn cn, bo v, da trn nn tnh ton tin cy... Vic khi ng cc phn mm cho cc im truy nhp phi c bo v bi mt ha nh l s dng mt TPM (Trusted platform module) v cp nht d liu cho ton b cc phn mm, thay i cu hnh cng phi c m bo bi mt ha. im truy nhp Femto phi c cung cp mt b hin th cho c mc ch bo v v cnh bo.

2.4.1. Nhn thc thit b Femtocell S dng UICC c xut trong 3GPP SA3 TR nh l mt ty chn iu khin h tr nhn thc thit b, tuy nhin cch tip cn ny c th khng phi l mt ty chn c s dng. S trin khai ca mt c cu ph hp ghp cp UICC v FAP s to iu kin cho vic nhn thc ca mt FAP vi mt th bi an ton nh l th UICC. Ghp cp an ton yu cu mt knh an ton c xy dng gia im truy nhp Femto v UICC. Mt v d trin khai c th hin trong ETSI TS 102 484. Mt c cu ghp cp thit thc, khng nhy cho kiu tha hip bo mt m c chng minh qua c cu kha SIM trong cc thit b di ng cm tay, c th c s dng gn kt UICC vi FAP. Nh vy c cu s gim nh , nu khng chng li, ri ro ca vic dng th bi nhn thc trong cc thit b cm. iu ny s ngn cc thit b cm c trang b vo cc b c UICC t truy nhp nhn c ti nh iu mng IP.

Thng tin chi tit c cung cp trong TR 33.820, TPM l bt buc v UICC cho my ch nhn thc l c kh nng iu chnh c s dng v trin khai trong FAP. 2.4.2. S y quyn Nhng ngi s dng yu cu mt im truy nhp Femto s mua t h thng phn phi bn l bao gm in thoi v my tnh. im truy nhp s cn phi cu hnh mng vi cc thng s ngi s dng v trong tt c cc trng hp bt k im truy nhp no u phi c hp php ha bi nh khai thc mng trc khi c th s dng dch v.

2.4.3. Cp php thut ton C th coi nh cc im truy nhp Femto s b tn cng cho php vic nghe trm v truy nhp bt hp php. Do , khi sn xut im truy nhp, mt iu quan trng l phi m bo theo kp cng ngh GSM v UMTS ngy nay v cc thut ton c trin khai trn nhng thit b ca chng.

2.4.4. Bo v chng gian ln Cc bin php bo mt phi ph hp vi vic trin khai tng im truy nhp femto c th. Mt s ng dng Femtocell c th khng ch c, hoc gy xung t vi mt s c cu bo mt c ng dng trong cng ngh di ng. c bit, cc th tc qun l tnh di ng ca Femtocell c th nh hng khng tt ti chc nng IMSI tm thi (TMSI), IMSI c yu cu truyn r rng hn.

Cc khuyn ngh t GSMA l cc giao din an ton c s dng gia im truy nhp Femto v mng di ng cung cp tnh bo mt c v gc vt l v logic ca cc d liu nhy cm v cc im truy nhp Femto, m bo n khng bao gi nm ngoi min c bo m trong im truy nhp Femto, ch c cc TMSI c s dng qua khng gian. Ch l thit b c kh nng c s dng cho cc mc ch phi php. Cc thit b Femtocell ch c cung cp cho nhng khch hng uy tn, khi iu ny b vi phm th c kh nng cc im truy nhp Femto c s dng thc hin cc cuc gi bt hp php...

2.4.5. Mng v bo mt Backhaul Vic kt ni im truy nhp Femto thng qua mng Internet cng cng v cc lin kt DSL to ra mt s vn v bo mt mi. Nhng vn ny bao gm t bo v chng li vic nghe trm cc cuc gi ti vic ngi s dng lp thm cc thit b thay i lung vo mng pha sau. Bt k gii php bo mt no cng phi iu khin mt cch hiu qu a cuc gi ng thi. S e da ng k nht tn ti trn vi mt cui cng ti im truy nhp Femto, chng thng da trn c s Ethernet. Xa hn, backhaul trn mng WAN l quan trng cp 2. gim nh nhng vn ny GSMA khuyn ngh lu lng im truy nhp Femto tr IP ni b, v lu lng Internet phi c an ton s dng IPSEC VPN thng qua xDSL backhaul (tuy nhin, ch l c nhng gii pho bo mt khc tn ti bao gm SRTP). Vi tt c lung lu lng c m bo an ton nh mt m ha bao gm lu lng ngi s dng v iu khin.

2.4.6. Bo mt nhn thc im truy nhp Femtocell Mi e da chnh cho s trao i ca cc Femtocell l s trin khai v s dng cc thit b nhi hoc khng hp php. S bo v phi c cung cp chng li cc im truy nhp bt hp php kt ni ti mng. S dng cc im truy nhp l n trm v khng r ngun gc phi c nh a ch bi nhn thc thit b c miu t trong khuyn ngh pha trn.

CHNG 3 : CC GII PHP KT NI FEMTOCELL TI MNG LI DI NG3.1. M u. Trong mng thng tin di ng th h th 3G UMTS, cc trm pht sng Node B (bao gm cc macro-cell, micro-cell hay c pico-cell) kt ni trc tip vi khi iu khin mng v tuyn RNC (Radio Network Controller) bng ng truyn dnh ring nh E1/T1. Cc RNC ghp cc lu lng d liu t cc Node B trc khi gi chng n mng li di ng. RNC phn pht lu lng thoi (ca mng chuyn ni mnh) n cc tng i MSC (Mobile Switching Center) thng qua giao din Iu-CS v d liu gi (ca mng chuyn ni gi) n SGSN (Serving GPRS Support Node) thng qua giao din Iu-PS. V l do gi thnh v tin li s dng, femtocell phi p ng tnh nng cm v chy (plug-and-play) ging nh cch m ngi ta ci t v s dng mt trm truy nhp WiFi. Trong tng lai, hng ngn femtocell s c ni kt vi kin trc mng li di ng thng qua mng cng cng Internet. iu ny t ra bi ton v kh nng m rng (scalability), tnh bo mt v s chun ha ca cc thit b v gii php. Di y, chng ta s cng tm hiu 4 gii php c ngh kt ni thit b femtocell n mng li di ng.

Hnh 3.1 Gii php kt ni Femtocell vi mng li3.2. Kin trc da trn UMTS. Gii php u tin i theo hng gi nguyn h tng mng nm pha sau RNC. Vic lin lc t cc femtocell v mng li s thc hin bng ng hm IP c bo mt thng qua mng IP bng rng cng cng. Chng ta c th phn ra 2 loi:Iubtrn IP(nung hm IPc thit lp gia femtocell v RNC) vIu trn IP(nung hmc thit lp gia RNC v MSC/SGSN). Trong khung gii php ny, Iu-concentrator (cn c gi l Femtocell Gateway FGW) c ngh nh im tp trung lu lng thng tin t hng nghn femtocelltrc khi i vo mng li di ng tng kh nng m rng (scalability).3.2.1. Gii php Iub trn IP Trong gii php ny, femtocell ng vai tr ca mt Node B, cn FGW s nm gia femtocell v RNC nh minh ha hnh 1. Gii php ny thch hp khi c t ngi kt ni vi femtocell cng lc (v d trong gia nh hay vn phng t ngi). Ty theo s lng femtocell kt ni vi FGW m FGW v RNC c th thit k trong cng mt thit b hay 2 thit b ring l. y ta xt trng hp chng tch bit nhau v lin lc gia FGW v RNC thc hin trn giao din Iub.

Hnh 3.2a gii php trn Iub trn IP

Hnh 3.2b Gii php IUb trn IP Femtocell c s xc thc gm 16 bit nh mt cell-ID. FGW c nhim v ghp lu lng t nhiu femtocell n v chuyn tip chng n RNC dng giao thc FP (Framing Protocol). Giao thc Iub c ng gi trong cc gi IP (cn gi l ng hm Iub). Bo mt s c m bo bi giao thc IPSec. Ngay lc u lp t, femtocell s to mt lin hip bo mt vi FGW trnh nhng thng tin thu bao gi n t mng IP cng cng. Femtocell dng TR-069 hay mt c ch tng t cu hnh a ch IP ca n t mt my ch cu hnh t ng ACS (Auto Configuration Server). RNC v FGW s cng nhau thc hin chc nng qun l ti nguyn, c bit dnh ring cho cc chuyn giao gia femtocell v macrocell. Nu mng li khng h tr truyn ti IP, RNC s lm nhim v chuyn i IP-sang-ATM v ngc li. Cc chc nng nh qun l di ng MM (Mobility Management) v iu khin cuc gi CC (Call Control) c thc hin bi mng li. Vi gii php ny, nu femtocell v macrocell cng thuc s qun l ca mt RNC, s chuyn giao gia femtocell v macrocell s thuc loi intra-RNC. Trong trng hp ngc li, s chuyn giao gia femtocell v macrocell s l inter-RNC. Khi chuyn giao t macrocell sang femtocell, the CN v UE s chn femtocell thch hp, thit lp bo hiu Iub v to ng hm vn ti thng qua mng IP cng cng gia FGW v femtocell. Ti nguyn v tuyn gia femtocell v UE c qun l bi giao thc RRC (Radio Resource Control) RNC. Mt khi vic thit lp ng hm Iub hon tt, mng li s chuyn cuc gi sang femtocell. Trong chuyn giao t femtocell sang macrocell, RNC s tin hnh thit lp kt ni vi macrocell trc khi chuyn cuc gi sang macrocell. Trong chuyn giao gia 2 femtocell, RNC s ng vai tr l nt neo (anchor) trong qu trnh thit lp ng hm Iub ti femtocell ch n. Tr ngi ca gip php ny nm gii hn m rng ca RNC p ng hng ngn Node-B (bao gm cc femtocell). khc phc phn no tnh trng ny, FGW c ngh. Mc dng giao din Iub l mt giao din chun nhng n li c thm nhiu c tnh ring ty thuc theo gii php ca nh cung cp thit b mng. Chnh v th, n thiu mt s nht qun chung gia nhng nh sn xut thit b khc nhau.3.2.2. IU trn IP. Trong gii php ny, cc femtocell s c tch hp vi mng li di ng thng qua cc FGW nh minh ha hnh 3. Nhng chc nng ca RNC v Node B s c ci t trn femtocell v do femtocell s lin lc vi FGW thng qua giao din 3G Iu trn IP. S nhn din ca femtocell trong trng hp ny khi lin lc vi FGWc dnga chca mt RNC (12 bits).FGWto ng hm cho cc thng ip bo hiu RANAP t femtocell n mng li. Nu mng li khng h tr vn ti IP,FGWs m nhim vic chuyn i giatruyn ti IP v truyn tiATM nh vogiao thc truyn ti bo tinSIGTRAN.Cng ging nh trn, trong gii php Iub trn IP, ngay khi lpt, femtocell s to mtlin hip bo mtviFGWv dng TR-069 hay mtc ch tng tcu hnha ch IP ca n. Thm voy, femtocell s s dngACS cu hnh ccthngsqun l ti nguyn cng nh thut tonthc hin trong mi trng femtocell.

Hnh 3.3 Kin trc gii php Iu trn IP FGWlimtptrunglu lng t hng ngn femtocell gin v tch gilu lng thoi v d liun tngi MSC v SGSN ging nh chc nng ca mt RNC.V d, thng tin thoi s c gi t femtocell n FGW dng RTP trn UDP, sau FGW s chuyn i thng tin thoi ny sang IP, ATM hay DTM tng ng vi truyn ti camng li. Tm li,FGWgi lp vai tr ca mng li dingi vi cc femtocell v gi lp RNCi vi mng li ding. Do vy, vi gii php ny ta khng cn bt c s thayi noh tng mng li.bo mt thng tin gi t femtocelln FGWqua mng IP cng cng,giao thc IPSecc chn dng.Mt cng bo mtsc citcng vi FGW. y cng chnh lim kt thc ca ccng hmIPSecn t ccfemtocell.

Hnh 3.4 B giao thc ca gii php Iu trn IP Khi ngi dng chuyn giao t femtocell sang mt macrocell, nu c 2 u cng thuc s qun l ca mt MSC/SGSN, chuyn giao ny s thuc loi inter-RNC. Nu khng, chuyn giao gia femtocell v macrocell s c thc hin nh mt chuyn giao inter-MSC/SGSN.Khi chuyn t mt macrocell sang mt femtocell, UE v CN s xcnh femtocell thch hpda vo danh schcc cell cn k, thit lp bo hiu Iu vng hmtruyn tigia femtocell v FGWthng quamng IP.Vic qun l ti nguyn gia femtocell v UEc thc hin nhsphi hp ca giao thc RRC v RANAP (nh hnh 4).Mt khing hm Iuc thit lp, mng li s chuyncuc githoi ti femtocell s dng giao thcqun l ding MM v giao thcqun l cuc gi CC MSC v UE.Trong qu trnh chuyn giao theo chiu ngc li, tc t femtocell sang macrocell, giao thc RANAP ti MSC v giao thc RRCti RNC ch n thit lp kt ni macrocell trc khi cuc gi c chuyn giao. i vi chuyn giao gia 2 femtocell, MSC/SGSN ng vai tr nh mt im neo thit lpng truyn vng hm Iu mi ti femtocellchn. Femtocellc chc nngqun l ti nguyn cc b gia femtocell v nhng ngi dng. Tuy nhin, cht lng dch v ph thuc vo s kt ni vi mng IP cng cng. Nhng vn nh tr IP hay mt gi tin d nhin s nh hng n cht lng dch v trn femtocell. y l mt gii php nhanhnht vn gin nht trin khai femtocell. Tuy nhin, do tt c dung lng t cc kt ni femtocells s v mng li,iu ny c th s dnn yu cu phi nng cp mng li.3.3. Kin trc da trn gii php UMA/GAN. Cng ngh UMA cho php thc hin cc dch v GSM /GPRS trn cc bng tn khng cp php (s dng cho Bluetooth v WiFi). UMA c 3GPP chun ha vi tn gi l cng ngh GAN (Generic Access Network). UMA/GAN ngh mt thc th mi gi l GANC (GAN controller), hay UNC (UMA Network Controller) thc hin cc chc nng ging nh mt b iu khin trm gc BSC trong GSM. GAN nh ngha mt giao din Up mi gia GANC v thit b di ng UE. V nguyn tc, femtocell cng ging nh UMA/GAN ngoi tr vic femtocell s dng bng tn cp php 2G/3G thay v bng tn khng php nh WiFi hay Bluetooth. Do vy, gii php UMA/GAN c th c m rng h tr gii php femtocell bng cch tch thm cc chc nng ca FGW vo trong b iu khin GANC. Hng gii php ny rt ph hp cho nhng nh cung cp mng trin khai h tng GAN/UMA cung cp thm cc dch v gi tr gia tng ca cng ngh HSPA (High Speed Packet Access). Kin trc kt ni s ging nh hnh 3. Tuy nhin cc lin lc gia femtocell v FGW s c thc hin trn giao din Up ca gii php UMA. Chng giao thc bo hiu ca gii php ny c minh ha hnh 5 di y.

Hnh 3.5 B giao thc ca gii php da trn UMA/GAN Trong gii php ny, FGW s ng vai tr nh mt GANC. FGW lin lc vi mng li bng giao din Iu. FGW xem femtocell nh mt thit b IP v do vy FGW lin lc vi femtocell bng a ch IP v s cng. Femtocell s chuyn i lu lng thoi t UE gi n sang gi ri chuyn n FGW trn giao thc truyn ti RTP/UDP. FGW phi chuyn i gi RTP tr li lu lng thoi trc khi gi n tng i MSC. Nhiu ln chuyn m trn nhiu mng truyn ti khc nhau c th dn ti gim cht lng thng tin thoi. Do vy, cn phi c cc c ch qun l QoS cht ch hn trn giao din Up. Qu trnh chuyn giao gii php ny da trn nguyn tc rt ging vi gii php Iub-trn-IP trnh by trn.3.4. Kin trc da trn IMS. Gii php ny nhm kt ni femtocell trc tip vi mng li IMS (IP Multimedia Subsystem). Mt gii php thay th trong cng hng ny l dng softwitch trong cc femtocell c kt ni vi cc softwitch thng qua giao din SIP (Session Initiation Protocol). Vic kt ni trc tip vi IMS li mang li nhiu li ch nh: gim ti lu lng cho mng li di ng v lu lng t cc femtocell s khng phi i qua mng li, gim thi gian truyn ti v gim s nt mng m mt gi thng tin phi i qua. Cui cng, y mt gii php di hn cung cp dch v a phng tin ca IMS trong tng lai. pha mng li IMS, femtocell c th giao tip trc tip vi softwitch thc hin chc nng CSCF (Call Session Control Function) thng qua giao thc SIP, giao tip vi HSS (Home Subscriber Server) thng qua giao thc Diameter cho chc nng xc thc, y quyn v tnh cc AAA (Authentication, Authorization, and Accounting) (nh minh ha hnh 6). Femtocell cng c th chn la giao tip vi cc thit b k trn thng qua mt cng gi d liu PDG (Packet Data Gateway). V kha cnh truyn ti thng tin thoi, femtocell s truyn lu lng thoi trn gi RTP n mng li IMS. Chng giao thc bo hiu minh ha s phi hp cc thc th mng c th hin hnh.

Hnh 3.6 Kin trc gii php da trn IMS/SIP

KT LUN V HNG PHT TRIN

H thng femtocell li ko s ch ca nhng nh cung cp dch v khng dy mc cha tng thy do nhng thun li ca femtocell nh l m rng vng ph cell, gia tng dung lng v m rng cht lng dch v trong mi trng trong nh. Nhng c tnh femtocell tin tin v ti u hn na s c mt trong giai on hai trong s hon chnh ca tiu chun IEEE 802.16m v l mt phn ca th h WiMAX 2.0 vi trin khai mc tiu vo nm 2012-2013.Nhng hot ng cng nghip bng n gia tng li cao tim nng trong vng ph v dung lng c hy vng t nhng trin khai femtocell, cng nh s lng ln trin khai on trc. Mt bo co mi y ca t chc d bo ABI vo nm 2012 s c s c 36 triu chuyn hng t vi c s ci t gn 70 triu femtocell qua 150 triu ngi dng. Vng ph khng tha mn v gia tng nhng ng dng t l d liu cao l hai mt thc y pht trin femtocell. Trong tng lai, nhng n lc c cng hin lm cho nhng nghin cu v femtocell i n thnh cng.Hn na nhiu ch cha c nghin cu trong giao din v tuyn IEEE 802.16m nh l tr gip ci t cng sut pht ng xung hoc iu khin cng sut ca femtocell v tr gip a sng mang trong femtocell. Nhng ch ny c th bao gm nghin cu nhng vn ca nhng th h chun tng lai. Vo thng 5 nm 2010 nhm nghin cu h thng lc s bt u v hin ang tip tc, mc tiu l m rng giao din v tuyn cho IEEE 802.16m cho trin khai a lp. Mt nhm cng tc chnh thc v vn ny ang c k vng lp ra.

DANH MC TI LIU THAM KHO1. http://en.wikipedia.org/wiki/Femtocell 2. http://www.femtoforum.org/femto/aboutfemtocells.php 3. http://www.lulu.com/product/paperback/femtocell-primer/3423204 4. Joseph Boccuzzi, Michael Ruggiero, Femtocells: Design & Application The McGraw-Hill (2011).