[Laptrinh.vn]-Wimax_mang Truy Nhap

H Cng Ngh - HQGHN

T-VT

Chng 1 Tng Quan V Mng Truy Nhp Bng Rng-WiMAX1.1 Mng Truy Nhp bng rng

nh ngha mng truy nhp:Theo cc khuyn ngh ca ITU-T(Lin minh vin thng quc t pht trin cc tiu chun quc t),mng truy nhp l mt chui cc thc th truyn dn gia SNI (Service Node Interface Giao din nt dch v) v UNI (User Network Interface Giao din ngi s dng - mng). Mng truy nhp chu trch nhim truyn ti cc dch v vin thng. Giao din iu khin v qun l mng l Q.

Q Mng truy nhp Cc thc th mng (PSTN , ISDN..)

Thu bao

UNI- Giao din ngi s dng mng

SNI- Giao din nt dch v

Hnh 1 :Kt ni mng truy nhp vi cc thc th mng khc Thit b u cui ca khch hng c kt ni vi mng truy nhp qua UNI, cn mng truy nhp kt ni vi nt dch v (SN Service Node) thng qua SNI. V nguyn tc khng c gii hn no v loi v dung lng ca UNI hay SNI. Mng truy nhp v nt dch v u c kt ni vi h thng qun l mng TMN (telecom management network) qua giao din Q. S thay i ca c cu dch v l yu t then cht nh hng n s pht trin ca mng truy nhp. Khch hng yu cu khng ch l cc dch v thoi/ fax truyn thng, m c cc dch v s tch hp, truyn hnh k thut s phn gii cao,..vv. Mng truy nhp truyn thng r rng cha sn sng p ng cc nhu cu dch v ny.. Trong nhng nm gn y mng truy nhp v tuyn bng rng tc cao khng ngng c nghin cu v pht trin ,cung cp cc dch v Multimedia nh:______________________________________________________________________ Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam 1

H Cng Ngh - HQGHN

T-VT

truy cp Internet, VoIP, in thoi truyn hnh (Video Telephony), hi ngh truyn hnh (Video conferencing), truyn hnh qung b (Broadcast TV), xem phim theo yu cu (Video on Demand), tr chi trn mng (Game online) .vv C th ni mng bng rng l xu hng pht trin tt yu.Sau y chng ta s cp ti mt s cng ngh truy cp bng rng in hnh l :xDSL, Modem cp ,iPSTAR v mt s k thut truy nhp v tuyn nh WiFi v WiMAX. 1.1.1 Mng xDSL [9] Truy nhp xDSL ( x Digital Subscriber Line ):ng dy thu bao s (xDSL ) l phng thc truyn thng tin s tc cao qua ng in thoi truyn thng v s l nn tng cho vic phn b dch v bng rng ny n cc thu bao. S d iu ny thc hin c l nh ng dng cc k thut truyn s phc tp, l s b tr cc suy gim truyn dn trn ng dy in thoi v cc b x l s c nng lc rt ln.Cng ngh ny tn dng c s h tng ng dy thu bao cp ng c sn Khi nng lc x l ca b x l tn hiu s tng ln, th tc ca xDSL cng tng ln. Cng ngh DSL bt u t 144 kbit/s, pht trin ti 1,5 n 2 Mbit/s HDSL, 7 Mbit/s vi ADSL, v by gi vi VDSL l 52 Mbit/s ng dy thu bao s bt i xng ADSL (Asymmetric DSL) -

S dng mt i dy cp xon Tc lung xung ln (1,5Mbps khong cch 6 km n 8Mbps vi khong cch 3 km).Tc hng ln t 16kbps n 640kbps

ng dy thu bao s tc thch nghi RADSL (Rate Adaptive DSL) -

S dng mt i dy cp xon Tc lung xung ln (1 Mbps n 12 Mbps vi).tc hng ln t 128 kbps n 1Mbps tc truyn i xng trong khong t 1 n 2 Mbps Cc modem RADSL c kh nng nh gi cht lng ng y v t ng iu chnh mc iu ch hoc s dng cc bc sng (ty thuc vo phng php m ha ng y)

ng dy thu bao s tc rt cao VDSL(very high bit rate DSL) Tc lung xung ln (30Mbps n 50 Mbps vi c ly ngn thng nh hn 300m . Tc truyn i xng trong khong t 2 n 4 Mbps v khong cch xa hn.______________________________________________________________________ Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam 2

H Cng Ngh - HQGHN

T-VT

Cc cng ngh xDSL i xng nh HDSL, SDSL, HDSL2-

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High bit rate DSL (HDSL)l mt trong nhng cng ngh u tin c khai thc . Tc truyn i xng 1.54 Mbps trn 2 i dy cp xon hoc 2Mbps trn 3 i cp xon.,HDSLversion 2 ging HDSL nhng ch s dng 1 i cp xon.Khong cch truyn l 4 Km SDSL (Symmetric DSL) s dng 1 i cp xon, vi tc h tr ln ti 2Mbps cho frame-relay hay truyn hnh hi ngh.,khong cch truyn khong 3 Km. C c im ly(km) 3.6 Khng s dung truyn dn c ca d liu va tin hiu thoai Ghep ca tin hiu thoai va d liu trn cung mt i dy Tc tai d liu cung vi tin hiu thoai khng cao Thch hp cho cac doanh nghip va va ln D trin khai do s dung c s mang in thoai sn co.Chi phi hp ly. S dung ng thi fax, voice ma khng cn ngt mang. Hoat ng Fulltime. Phu hp vi cac doanh nghip va va ln S dung ng thi fax, voice tich hp Splitter Cha c h tr bi cac ISP chi dung cho mang LAN m rng Bng 1 :Cc cng ngh xDSL ng dng Mng cung cp T1/E1 , truy sut WAN, LAN Ni ht, thay th trung k T1/E1c dng b lp,Kt ni cc PBX vi nhau, Kt ni mng LAN

Tn

Tc d liu HDSL 1.544 (kbps) 2.048 (kbps) SDSL

1.5447(kbps) 3.6 2.048(kbps)

ADSL 1.5-9 Mbps 16-640 (kbps)

5

Truy nhp internet,/intranet video theo yu cu,VPN,VoIP ,truy nhp LAN t xa

VDSL 13-52 Mbps 1.5-2.3 Mbps

1.4

Truy nhp Mutimedia intern et.cc trng trnh broadcard TV

______________________________________________________________________ Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

3

H Cng Ngh - HQGHN

T-VT

Nhng u im v hn ch ca cng ngh xDSL: -

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Gim gi thnh v tc trn khai nhanh nhng khu vc m mng cp ng c sn C th trin khai trn din rng vi nhiu loi m hnh khc nhau sn sng ca mng cp ng mt s ni nh vng nng thn ,vng su vng xa , hoc hi o hu nh khng c ,v nu c th cht lng ca mng cp ng cha t yu cu nn m bo tc truy nhp cao DSL l rt kh. Vng ph nh, bn knh phc v t l nghch vi tc truy nhp nn mc u t s cao vng phn tn rng. Khng c tnh di ng.

1.1.2 Modem cp [5] Modem cp l thit b c dng chuyn d liu trn cc ng truyn cho truyn hnh cp. Loi ng truyn ny, l cp ng trc, mang li bng thng ln hn nhiu so vi ng in thoi thng thng. Ni modem ny vi cp truyn v vi PC s mang li kh nng truy cp Internet tc cao.Trn l thuyt, tc ti xung ca cc thit b ny c th t 35M bit/s, nhng thc t thng ch t 1,5M bit/s, ty thuc vo nh cung cp dch v cp. Tc gi thng ip i t PC, cn c gi l tc ti ln vo khong 128K bit/s, u nhc im ca Modem cp l: - Vic dng chung lm nh hng n tc . truy cp mng s t l nghch vi s ngi truy cp trn cng mt nt mng - Mt vn khc cng c quan tm l tnh bo mt, - Kh trin khai trn nhng vng n c phn tn . - Khng c tnh di ng - Chi ph cao,v do phi lp t ng cp truyn hnh l nhng nguyn nhn m dch v ny khng c pht trin ph bin.1.1.3

Truy nhp dch v bng rng qua v tinh (iPSTAR) [12]:

H thng v tinh c nh:VSAT(Very Small Aperture terminal) c trin khai ch yu cc tnh min ni ca Vit Nam. Cc h thng ny c th cung cp tc t 9.6Kbps dn 8Mbps. Vit Nam hin ang s dng hai h thng VSAT DAMA/SCPC ch y phc v cho vng su vng xa v VSAT TDM/TDMA phc v cho nhu cu internet .[5] Nhc im chnh ca cc h thng ny l gi thnh cao,tr hnh trnh ln v chu nh hng ca thi tit.


4

H Cng Ngh - HQGHN

T-VT

gim thiu nhng hn ch trn cng ty SSA-nh khai thc v tinh hng u chu pht trin h thng VSAT IP hay iPSTAR.i iPSTAR c nh gi l h thng v tinh bng rng a dch v em li nhiu tin ch.H thng thng tin v tinh bng rng iPSTAR h tr truyn s liu theo hng xung tc 4Mbps v 2Mbps hng ln..Cung cp cc dch v vin thng trn nn giao thc IP. c im ca VSAT-IP l thit b gn nh, d lp t, gi thnh thp hn nhiu so vi VSAT DAMA. V tin ch, VSAT-IP ngoi cung cp dch v in thoi, cn c kh nng cung cp cc ng dng m ch c dch v bng rng nh: thoi VoIP, Internet tc cao, truyn hnh hi ngh, mng ring o (VPN), knh thu ring, trung k mobile, truyn hnh qung b, truyn hnh theo yu cu. Vi dung lng h thng 35 Gbit/s. Dch v truy nhp bng rng cho vng nng thn c th thc hin qua truy nhp v tinh bng rng 2 ng.

Hnh 2 h thng truy nhp v tinh iPTSAT Nhng u im v nhc im: - Cc h thng thng tin v tinh c phm vi trin khai dch v ln, khng ph thuc vo a bn, c th trin khai vng su vng xa ,nhng ni c a hnh phc tp m khng th trin khai c cc h thng nh xDSL . - Hn ch ca truy nhp bng rng qua v tinh l s ph thuc ca nh cung cp dch v vo nh qun l h thng v tinh. Hin nay, VNPT mua dung lng 2,5 Gbit/s trin khai dch v VSAT bng rng Vit Nam. Vic mua dung lng s ph thuc vo chnh sch ca nh qun l h thng iPSTAR. Bi vy, gii php ny khng th trin khai c lp trong vng nng thn khi lng khch hng ln, n cn phi kt hp vi cc gii php truy nhp mt t khc.


5

H Cng Ngh - HQGHN

T-VT

-

Ngoi ra, chi ph trin khai dch v cao, tui th ca h thng iPSTAR theo thit k l 12 nm v th gi thnh bng tn s khng gim d nhu cu s dng tng. Mng truy nhp v tyn

1.1.4

Hin nay mng truy nhp v tuyn bng rng c xu hng pht trin nhanh hn so vi cc cng ngh truy nhp bng rng khc. L do l cng ngh ny c nhiu u im khi trin khai trn a hnh him tr m mng cp kh c th trin khai. So vi s dng v tinh th phng n ny c chi ph thp hn rt nhiu. n nay c rt nhiu cng ngh v tuyn kt ni bng rng mi, Trong lun vn ny ch cp n mt s cng ngh v tuyn bng rng sau. a/ HIPERLAN [14] HIPERLAN- L h thng cc chun cho WLAN ca vin tiu chun vin thng chu u ETSI- European Telecommunications Standards Institute. Nm 1991, ETSI thnh lp nhm RES10 .Nhm RES10 xy dng tiu chun HIPERLAN l chun thng tin lin lc s khng dy tc cao bng tn 5,1-5,3GHz v bng tn 17,2-17,3 GHz. C 4 loi HIPERLAN c a ra:HIPERLAN/1, HIPERLAN/2, HIPERCESS v HIPERLINK.vo nm 1996. HYPERLA N1 Wireless LAN 2.4 GHz 23.5 Mbps HYPERLA N2 Truy nhp WATM 5 GHz 54 Mbps HYPERLAN HYPERLAN 3 4 Truy nhp Kt ni PTP WATM c WATM nh t xa 5 GHz 17 GHz 54 Mbps 155Mbps

ng dng Bng tn Tc t c

Bng 2 Cc tiu chun ca ETSI HYPERLAN Cc chun m ETSI thit lp nh HiPerLAN/2 l mt chun cnh tranh trc tip vi chun 802.11 ca IEEE. Sau IEEE a ra chun 802.11h c th tng tc c vi chun HiPerLAN/2 ca ETSI. Trc , chun HiPerLAN/1 h tr tc ln n 24 Mbps s dng cng ngh DSSS trong phm vi 50m.HiPerLAN/1 s dng bng tn UNII thp v trung bnh ging nh HiPerLAN/2, 802.11a v 802.11h. HiperLAN2 [5].______________________________________________________________________ Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam 6

H Cng Ngh - HQGHN

T-VT

Trong cc chun ca HiperLAN, HiperLAN2 l chun c s dng rng ri nht bi nhng c tnh k thut ca n. Tc truyn d liu ca HiperLAN2 c th t ti 54 Mbps.C- th t c tc v HiperLAN2 s dng phng php gi l OFDM (Orthogonal Frequence Digital Multiplexing dn knh phn chia tn s). OFDM c hiu qu trong c cc mi trng m sng radio b phn x t nhiu im. HiperLAN Access Point c kh nng h tr vic cp pht tn s t ng trong vng ph sng ca n. iu ny c thc hin da vo chc nng DFS(Dynamic Frequence Selection) Kin trc HiperLAN2 thch hp vi nhiu loi mng khc nhau. Tt c cc ng dng chy c trn mt mng thng thng th c th chy c trn h thng mng HiperLAN2. u nhc im ca HIPERLAN-

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HIPERLAN bo mt tt hn IEEE802.11 HIPERLAN2 c h tr QoS ,v cc HIPERLAN cn h tr cc loi mng li khc nh ATM,kt ni Ethernet trong khi 802.11 ch h tr kt ni Ethernet HIPERLAN 2 cn c c tnh u vit nh c kh nng chn tn ng ,iu khin cng sut. Hn ch ca HIPERLAN l pham vi ph sng gii hn 50m Gi thnh thit b cao.

b/ WiFi WiFi l mt nhn hiu cho dng sn phm tun th theo cc chun cho WLAN ca Vin k thut in t IEEE(Institute of Electrical and Electronics Engineers) vi cc chun sau: Chun IEEE 802.11 802.11b 802.11a 802.11g 802.11n 802.11e 802.11f 802.11i Tc max: Phm vi (m) Mbit/s 2 11 54 54 320 iu ch 64-QAM. b\Truyn cc MAC PDU Cc MAC PDU c truyn trong cc burst. Cc burst PHY c th cha nhiu khi FEC. Cc MAC PDU c th ko di qua cc ng bin khi. Qu trnh truyn gm cc bc sau: - Ghp ni - Phn on - ng gi - Tnh CRC - m Quy c Cc trng ca bn tin MAC s c pht theo th t nh xut hin trong cc bng trn.Cc trng ca bn tin MAC v cc trng ca TLV, c ch ra l cc s nh phn (bao gm CRC v HSC) s c pht nh mt chui cc digit nh phn ca chng, bt u t MSB. Cc mt n bit (v d nh trong ARQ) c xem nh cc trng s. Cc s MSB nh du c nh v lm du. Trng di trong dng xc nh ca ITU-T X.690 cng c xem nh mt trng s. Cc trng c ch th nh cc SDU hay phn on SDU (v d ti trng MAC PDU) c pht theo th t cc byteb nh nhn c t lp trn.______________________________________________________________________ 33 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

Cc trng ch th nh cc chui cng c pht theo th t cc symbol trong chui.Trong trng hp 3 v 4, cc bit trong mt byte c pht theo nguyn tc MSB trc. Bc 1:Ghp ni MAC PDU C nhiu MAC PDU c ghp ni trong cng mt burst PHY. Cc MAC PDU c th c ghp trong mt lung truyn dn n ng ln hoc ng xung. Do mi MAC PDU c nhn dng bi mt CID, thc th MAC nhn c th to ra MAC SDU (sau khi lp rp MAC SDU t mt hay nhiu MAC PDU nhn) n trng hp chnh xc ca MAC SAP. Cc bn tin qun l MAC, d liu ngi dng, v cc MAC PDU yu cu bng tn c th c ghp vo cng mt lung truyn dn.

Hnh 8 :Ghp ni MAC_PDU Bc 2:Phn on MAC PDU Mi MAC SDU c th c phn on thnh nhiu phn on, mi phn on c ng gi thnh mt MAC PDU. Qu trnh ny c m bo cho php s dng bng tn c sn hiu qu lin quan n cc yu cu QoS ca mi lung dch v ca mt kt ni. Kh nng phn on v lp rp l bt buc.

______________________________________________________________________ 34 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

tin cy ca lu lng phn on trn mt kt ni c nh ngha khi kt ni c to ra bi MAC SAP. Vic phn on c th c khi to bi BS cho cc kt ni ng xung v bi SS cho cc kt ni ng ln. Cc kt ni khng ARQ: vi cc kt ni khng ARQ, cc phn on c pht ch mt ln v theo tun t. S tun t c gn cho mi phn on cho php u thu ti to li ti trng ban u v pht hin mt bt k gi no ngay lp tc. Mt kt ni c th ch c mt trng thi phn on mt thi gian bt k cho trc Cc kt ni ARQ: vi cc kt ni ARQ, phn on c nh dng cho mi lung truyn dn bng cch ghp mt tp hp cc khi ARQ vi cc s tun t lin nhau.Gi tr BSN trong tiu con phn on l BSN cho khi ARQ u tin xut hin trong phn on. FSH l tiu con phn on c di 8 bit.

Hnh 9: Phn on MAC_PDU Bc 3 :ng gi cc MAC PDU ng gi c thc hin trn mi kt ni, MAC c th gi nhiu MAC SDU vo mt MAC PDU n. ng gi to ra vic s dng ch s thuc tnh kt ni l kt ni mang cc gi c di thay i hay di c nh. Pha pht hon ton ch ng trong vic ng gi hay khng mt nhm cc MAC SDU trong mt MAC PDU n. Kh nng khng ng gi l bt buc. Cu trc ca cc PDU thay i vi cc kt ni ARQ v khng ARQ vi cc c php phn on v ng gi c th.


H Cng Ngh - HQGHN

T-VT

Vi cc kt ni khng s dng ARQ: ng gi cc khi c di c nh, iu khon Request/ Transmission c thit lp cho php ng gi v cm phn oan,v kch c SDU s c bao gm trong bn tin DSA-REQ khi thit lp kt ni. Trng di tiu MAC biu th s cc MAC SDU c gi trong mt MAC PDU n. Nu kch c MAC SDU l n byte, pha thu c th m gi bi bit rng trng di trong tiu MAC s l (nk+j) vi k l s MAC SDU c ng gi trong MAC PDU v j l kch c tiu MAC. Mt MAC PDU cha mt chui cc MAC SDU c gi. Khng c thm tiu do ng gi trong trng hp MAC SDU di c nh v mt MAC SDU n th n gin l mt chui c gi c di l 1. Khi ng gi cc kt ni MAC SDU di thay i, MAC gn mt tiu con gi (PSH) cho mi MAC SDU. Mt MAC PDU bao gm mt chui cc MAC SDU di thay i c ng gi. Nu c hn mt MAC SDU c ng gi, trng Type trong tiu MAC ch th s c mt ca cc PSH. Khi mt PSH c mt, thng tin phn on cho cc MAC SDU c th hay cc phn on MAC SDU c cha trong PSH tng ng. Nu khng c PSH, thng tin phn on cho cc phn on MAC SDU c th c cha trong tiu con phn on (FSH) tng ng. Vi cc kt ni cho php ARQ: S dng PSH cho mi kt ni tng t nh trn, ngoi tr cc kt ni ARQ s thit lp bit Extended Type trong tiu MAC chung. Nu ng gi c thc hin cho mt kt ni, MAC c th gi nhiu MAC SDU vo trong mt MAC PDU n. Gi cc MAC SDU c di thay i cho cc kt ni cho php ARQ tng t cc kt ni khng ARQ khi phn on c cho php. BSSN ca PSH s c dng bi giao thc ARQ nhn dng v pht li cc phn on mt. Khi trng Type ch th rng PSH c dng, thng tin phn on cho mi MAC SDU c th hay phn on MAC SDU c cha trong PSH kt hp. Khi PSH khng c dng, thng tin phn on cho mi ti trng ca MAC PDU (MAC SDU hay phn on MAC SDU) c cha trong FSH. Mt MAC SDU c th c chia thnh nhiu phn on v sau c gi trong cng mt MAC PDU cho ln truyn u tin. Cc MAC PDU c th c cc phn on t cng mt SDU hay cc SDU khc nhau, bao gm s trn ln gia ln truyn u tin v ln truyn li. Cc trng BSN (11 bit) v FC (2 bit) nhn dng mi SDU phn on hay SDU khng c phn on. Khi ng gi cc MAC SDU kch c c nh th khng cn thit cc tiu con gi. Cc MAC SDU loi ny v d nh cc t bo ATM trn cng mt kt ni.


H Cng Ngh - HQGHN

T-VT

Cc MAC SDU kch c thay i v d nh cc gi IP trn cng mt kt ni. Khi ng gi chng cn phi c tiu con gi PSH c di 16 bt.

Bc 4:Tnh CRC Mt lung dch v c th yu cu CRC thm vo mi MAC PDU mang d liu cho lung dch v . Trong trng hp ny vi HT=0, mt CRC s c gn vo ti trng MAC PDU. CRC s kim sot tiu MAC chung v ti trng MAC PDU. CRC s uc tnh ton sau khi mt m ha chng hn CRC bo v tiu chung v mt m ha ti trng. Mt m ha cc MAC PDU Khi pht mt MAC PDU trn mt kt ni c nh x n mt SA, pha gi s thc hin mt m ha v nhn thc d liu ca ti trng MAC PDU khi c ch th bi SA. Khi nhn mt MAC PDU trn mt kt ni c nh x n mt SA, u thu s thc hin gii mt m v nhn thc d liu ca ti trng MAC khi c ch th bi SA.


H Cng Ngh - HQGHN

T-VT

Tiu MAC chung s khng c mt m ha. Tiu cha tt c thng tin mt m ha (trng EC, trng s tun t kha mt m EKS v CID) cn gii mt m mt ti trng trm thu. Hai bit ca tiu MAC cha mt s tun t kha. Kha kt hp vi mt SA c thi gian sng hn ch v BS theo nh k lm mi kha ca SA. BS qun l 2 bit s tun t kha c lp vi mi SA v phn phi s tun t kha ny cho mi ln to ra kha mi. Tiu MAC bao gm s tun t nhn dng vic to c th mt kha SA c s dng mt m ha ti trng c gn. L mt con s 2 bit, s tun t t 0 n 3. So snh s tun t kha ca MAC PDU nhn vi ci m n tin tng l s tun t kha hin hnh, BS hay SS c th d dng nhn ra mt ng b kha. Mt SS s duy tr hai kha mi nht cho mi SA. Gi hai kha ny l cn thit duy tr cho dch v khng ngt qung trong khi chuyn tip kha ca SA. Mt m ha ti trng c ch th bi trng bit EC. Gi tr 1 cho bit ti trng c mt m ha v trng EKS cha d liu c ngha. Gi tr 0 cho bit ti trng khng c mt m ha. Bt k MAC PDU no cha m ha c nhn trn mt kt ni nh x n mt SA yu cu mt m ha th d liu s b loi b. Bc 5 :m Khng gian c n nh trong mt burst d liu m cha c s dng s c khi to cho mt trng thi c nhn bit. iu ny c th c hon thnh bng cch thit lp mi byte cha dng thnh mt gi tr byte m (0xFF). Nu kch c vng cha s dng t nht l kch c ca tiu MAC, vng ny cng c th c khi to bng cch nh dng khng gian cha s dng mt MAC PDU. Khi lm vic , trng CID tiu MAC s c thit lp gi tr ca CID m, cc trng Type, CI, EC, HT s c thit lp l 0, trng di s c thit lp s byte cha s dng (bao gm c kch c tiu MAC to ra cho MAC PDU m) trong burst d liu v HCS s c tnh ton theo cch thng thng. c\ Mt s k thut trong lp MAC_SAP K thut ARQ: K thut ARQ dng truyn li cc khung b li khng sa c bi FEC. Khi c b sung, ARQ c th c cho php trn mi kt ni. Mi kt ni ARQ s c nh r v thng lng trong khi to kt ni. Mt kt ni khng th c s pha trn gia lu lng ARQ v khng ARQ.


H Cng Ngh - HQGHN

T-VT

Vi cc kt ni ARQ, cho php phn on l ty chn. Khi phn on c cho php, u pht c th phn chia mi SDU thnh nhiu phn on truyn dn ring bit da trn gi tr ca tham s ARQ_BLOCK_SIZE. Khi vic phn on khng c php, kt ni s c qun l ging nh khi c php. Trong trng hp ny, lin quan n kch c khi tha thun, mi phn on c nh dng truyn dn s cha tt c cc khi d liu kt hp vi SDU gc. K thut ny cho php tng tin cyh ca dch v nhng ng thi gim dung lng ng truyn v tng thi gian tr K thut yu cu v cp pht bng tn thc hin qu trnh yu cu v cp pht bng tn s c cc qu trnh nh polling yu cu v cp pht: Phn Polling: Polling l qu trnh c s dng bi BS cp pht cc c hi yu cu bng tn cho cc SS. Khi BS mun thng bo cho mt SS mt c hi yu cu bng tn ang n, n s s dng mt phn t thng tin IE bn tin UL-MAP lm vic . UL- MAP IE s chp nhn bng tn cho SS hay cc SS xem xt cc yu cu bng tn ca chng trong chu k yu cu theo l thuyt. Cp pht c hi yu cu bng tn s c thc hin trn c s n im, a im, hay qung b. Polling n im :Trong trng hp ny, mt SS c kim sot vng mt cch ring bit bi BS. SS s tr li vi cc byte trn nu bng tn c cp l khng cn thit. Polling a im v qung b: BS s s dng n kim sot vng a im hay qung b n cc SS nu bng tn ang sn c khng kim sot nhiu SS mt cch ring bit. Cc CID bt k c d tr cho cc nhm a im v cho cc bn tin qung b. Kim sot vng a im hay qung b cng c thc hin qua bn tin UL-MAP trong cng mt kiu vi polling n im. S khc bit c bn y l bn tin polling c nh hng n mt CID a im hay qung b thay v CID c th hoc SS. Poll-me bit: Poll-me bit c s dng bi cc SS s dng dch v UGS thng bo cho BS rng chng cn c kim sot vng. Poll-me bit l mt phn ca tiu con qun l cp pht. Khi poll-me bit c pht hin, BS s s dng mt polling n im n SS yu cu n. gim thiu nguy c BS lm mt Poll-me bit, SS c th thit lp bit trong tt c tiu con qun l cp pht MAC UGS khong thi gian lp lch ng ln.______________________________________________________________________ 39 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

Phn Yu cu: l k thut m cc SS s dng thng bo cho BS rng n cn c cp pht bng tn ng ln. Mt yu cu c th n nh mt tiu yu cu bng tn ng mt mnh hoc c th n nh mt PiggyBack Request. Bi v profile burst ng ln c th thay i linh ng, nn tt c cc yu cu bng tn s c to thnh s hng ca s cc byte cn mang tiu v ti trng MAC, nhng khng tnh lp vt l. Bn tin yu cu bng tn c th c pht trong bt k thi im no ng ln ngoi tr trong khong thi gian Initial Ranging. Bandwidth Request Header: SS c th yu cu cp pht bng tn vo bt k thi im no bng cch gi mt MAC PDU yu cu bng tn vi mt tiu yu cu bng tn v khng c ti trng. Tiu yu cu bng tn c s dng yu cu thm bng tn. Piggyback Request : Phng php thng dng yu cu bng tn s dng mt tiu con qun l cp pht mang mt yu cu cho bng tn thm vo cho cng mt kt ni trong MAC PDU. Mang mt bn tin BW Request trn mt gi d liu. Yu cu bng tn c th l tng dn hoc ton b. Khi BS nhn mt yu cu bng tn tng dn, n s ghi nh s lng bng tn c yu cu hin thi ca kt ni. Trng Type trong tiu yu cu bng tn cho bit yu cu l tng dn hay ton b. Do PiggyBack Request khng c trng Type, nn n s lun l tng dn. Phn Cp pht Cp pht trn mi kt ni (GPC): SS ch nhn cc cp pht cho cc kt ni c th (bao gm c cc kt ni qun l) v kt qu phi yu cu bng tn cho mi kt ni c th khi c nhu cu. Hn na, SS phi yu cu thm bng tn p ng cc yu cu ca RLC khng c mong i. V th, cc h thng GPC l n gin nhng khng hiu qu. Vic cp pht c quyt nh da trn bng tn yu cu v cc yu cu QoS v ti nguyn sn c. Cp pht trn mi trm thu bao (GPSS): SS nhn mt cp pht bng tn c s dng p ng cc nhu cu ca tt c cc kt ni ca n. T SS phi qun l bao nhiu bng tn c cp pht cho mi kt ni. Nu mt kt ni yu cu nhiu hn bng tn c th phc v, SS c th ly cp bng tn t mt kt ni khc lp y lng bng tn cn thiu. BS cng m nhn hng i u tin trn c s cc loi lu lng. SS sau c th gi mt yu cu n BS yu cu tng thm bng tn nhm p ng cc nhu cu mi ca n.______________________________________________________________________ 40 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

Cc cp pht bng tn c cung cp trn c s giao thc t hiu chnh tri ngc vi giao thc bit trn. Trong giao thc ny, nu SS khng nhn mt cp pht bng tn tr li yu cu bng tn ca n, SS s tha nhn rng yu cu b mt hay tr li khng c tha mn, v n gin s gi mt yu cu khc n BS m khng i mt s xc nhn ca yu cu ban u. Giao thc ny b qua tiu kt hp vi cc bn tin xc nhn. K thut dch v lp lch ng ln Cht lng dch v ni n kh nng cung cp u tin cho cc dch v khc nhau ca mng. Cc tham s chnh ca QoS trong mng bao gm rng bng tn chuyn dng, gc tr, jitter v t l mt. C nhiu dch v vi QoS khc nhau, iu ny c ngha l cc dch v khc nhau c cp pht cc ti nguyn khc nhau v cht lng dch v m bo. Phn loi dch v ng ln da trn cc yu cu khc nhau v bng tn, gc tr v jitter. Dch v cp pht khng yu cu (UGS) :Ti nguyn v tuyn ng ln c cp pht mt khong thi gian nh k. B lp lch BS a ra bng tn ng ln kch c c nh chp nhn c s thi gian thc theo chu k.Dch v UGS c thit k cho cc lung lu lng thi gian thc m pht cc gi d liu kch c c nh trn nn tng nh k nh T1/E1 v VoIP. Dch v kim sot vng thi gian thc (rtPS) Dch v ny cung cp cc c hi yu cu truyn dn ng ln cc khong thi gian c nh. Theo cch ny, ti nguyn trc ht phi c yu cu v sau c cp pht bi im truy nhp. Thng tin v cc ngun ti nguyn c cp pht trong ng ln l qung b thng qua ng xung n tt c cc u cui ngi dng. Dch v rtPS c dnh cho cc lung lu lng thi gian thc m pht cc gi d liu kch c thay i trn nn tng nh k nh l video MPEG. B lp lch BS a ra cc c hi yu cu bng tn ng ln theo nh k, thi gian thc. SS s dng c hi yu cu UL-BW a ra ch nh vic chp nhn UL-BW c mong mun. SS khng th s dng yu cu BW trn c s tranh chp. Dch v kim sot vng phi thi gian thc (nrtPS):Dch v ny cung cp k thut lp lch ng ln ging nh rtPS m khng thm d gc tr thp. Ph hp nht vi cc lung lu lng phi thi gian thc yu cu d liu kch c thay i chp nhn trn nn tng cch u nhau nh l FTP rng di tn cao. Cho cc dch v nrt-VBR nh truyn tp, cn nhiu rng di tn. B lp lch BS s cung cp cc c hi yu cu UL-BW theo thi gian (khong 1s hay t hn). SS c th s dng cc c hi yu cu BW trn c s tranh chp gi yu cu BW. Dch v Best Effort (BE):Vi dch v ny, cc khong thi gian yu cu tranh chp, cc c hi yu cu n im hay cc loi burst chp nhn d liu c th______________________________________________________________________ 41 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

c cp pht. Trong cch ny, cc yu cu ti nguyn c th tranh chp ch trong khi kt ni ang xy ra. Cc gi d liu c pht qua cc ti nguyn c dnh ring theo cc yu cu ti nguyn bi b lp lch ng ln trong im truy nhp. Cho lu lng best-effort v d nh HTTP, SMTP. SS s dng cc c hi yu cu BW trn c s tranh chp. 2.2.3 Lp MAC_PS [2] Hai chc nng chnh: - Bo mt qua cc khng gian truyn dn. - Bo v khi cc nh cp dch v. Lp con bo mt thc hin m ha d liu trc khi truyn i v gii m d liu nhn c t lp vt l. N cng thc hin nhn thc v trao i kha bo mt. Chun IEEE 802.16 ban u s dng phng php DES 56 bit cho m ha lu lng d liu v phng php m ha 3-DES cho qu trnh trao i kha. Trong mng IEEE 802.16, trm gc cha 48 bit ID nhn dng trm gc (ch rng y khng phi l mt a ch MAC), cn SS c 48 bit a ch MAC 802.3. C 2 giao thc chnh hot ng trong lp con bo mt: giao thc m ha d liu thng qua mng bng rng khng dy, v giao thc qun l kha bo v bo mt (PKM- Privacy and Key Management Protocol) m bo an ton cho qu trnh phn phi kha t BS ti SS. N cng cho php BS t iu kin truy nhp cho cc dch v mng. Giao thc PKM s dng thut ton kha cng khai RSA, chng thc s X.509 v thut ton m ha mnh thc hin trao i kha gia SS v BS. Giao thc bo mt ny da trn giao thc PKM ca DOCSIS BPI+ c ci tin cung cp mt lc m ha mnh hn nh chun m ha ci tin AES. MAC trong IEEE 802.16 l phn lp hng kt ni, c thit k cho cc ng dng truy nhp khng dy bng rng theo cu hnh im a im (PMP), hay dng mesh. C hai loi kt ni MAC c xc nh bi 16 bit nhn dng kt ni CID l: Cc kt ni qun l v Cc kt ni vn chuyn d liu. Cc kt ni qun l li gm 3 loi: c s, s cp th cp

Trong c s s dng cho truyn ti, iu khin lin kt v tuyn...,cn s cp lin quan n thit lp nhn thc v kt ni, v kt ni qun l th cp l cc bn tin qun l da trn chun truyn ti nh DHCP, TFTP, SNMP. Kt ni qun l s cp v kt ni c s c to ra khi mt MS/SS ra nhp vo mt BS phc v ca mng. Kt ni vn chuyn d liu c th c thit lp da trn nhu cu. Chng______________________________________________________________________ 42 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

c s dng cho cc lung lu lng ngi s dng, cc dch v n hng (Unicast) v a hng (Multicast). Cc knh b sung cng c MAC d tr gi ra ngoi cc thng tin lp lch ng xung v ng ln. Cc thnh phn c bn ca mng l trm gc BS v trm thu bao SS (Subscriber Station), trm gc BS ging nh cc im truy nhp (AP) trong mng WiFi. BS c ni vi phn hu tuyn, n pht qung b cc thng tin ti SS. Khc vi phng php CSMA/CA trong 802.11, 802.16 s dng cc nh x ng xung v ng ln khc phc xung t trong mi trng truy nhp. SS s dng phng thc truy nhp TDMA chia s ng ln trong khi BS s dng phng thc TDM. Tt c cc chc nng ny c thc hin thng qua bn tin DL_MAP v UL_MAP. 2.2.4 c im lp MAC ca WiMAX a/ QoS im ni bt trong kin trc MAC trong IEEE 802.16 l QoS.Ging nh mi h thng h tr QoS khc, vic phn loi dch v cng l im ct li trong vic m bo QoS. Xem cc loi hnh dch v QoS trong bng di y: QoS ph thuc vo 3 yu t sau: Giao thc MAC hot ng hng kt ni (connection oriented). Mi mt gi tin u c a vo mt kt ni c th, kt ni ny l kt ni o, c xc nh bi tham s CID. Vic to nn cc kt ni o ny khin cc gi tin c gi i mt cch hiu qu v nhanh chng. C ch cp pht bng thng Request/Grant: C ch ny lm tng hiu qu s dng bng thng ca h thng, c bit l cc h thng m c nhiu thu bao. Trong c ch ny, MS yu cu thng lng bng thng cp pht t BS thng qua mt s cc phng thc khc nhau. BS s cp pht bng thng bng cch cp pht cc timeslot ti cc MS c yu cu. C ch lp lch (scheduling) trong WiMAX khng c qui nh c th trong chun. C nhiu hnh thc lp lch khc nhau, mc ch l lm th no s dng ti nguyn UL va DL mt cch c hiu qu nht trong khi lun m bo c QoS yu cu.

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-


H Cng Ngh - HQGHN

T-VT

Bng 6: Dch v QoS Yu cu QoS Dch v cho php t nguyn (Unsolicited Grant ServiceUGS) Dch v thi gian thc(Real time Polling servicertPS) Dch v thi gian m rng (Extnded Real time Polling service-ErtPS) Dch v khng theo thi gian thc (Non Real time Polling service-nrtPS) Dch v tt nht(Best Effort Service -BE) b/ iu khin cng sut WiMAX di ng h tr hai ch vn hnh l: Sleep Mode v Idle Mode tit kim nng lng tiu th. Sleep Mode l trng thi m MS trong giai on trc khi c bt c trao i thng tin g vi trm gc qua giao din v tuyn. Sleep Mode cho php MS ti thiu nng lng tiu th v ti thiu ti nguyn v tuyn ca trm gc. Sleep Mode cng cung cp kh nng linh hot cho MS d cc trm gc khc thu thp thng tin h tr chuyn giao trong Sleep Mode. Idle Mode cung cp mt c ch cho MS sn sng mt cch nh k nhn cc bn tin qung b DL m khng cn ng k vi mt trm gc xc nh no khi MS di chuyn trong mt mi trng c ng truyn v tuyn c ph sng bi nhiu trm gc.______________________________________________________________________ 44 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

ng dng VoIP

c tnh k thut Tc duy tr ti a Dung sai tr ti a Dung sai jitter Tc knh dnh ring ti thiu Tc duy tr ti a Dung sai tr ti a u tin lu lng Tc knh dnh ring ti thiu Tc duy tr ti a Dung sai tr ti a Dung sai jitter u tin lu lng Tc dnh ring ti thiu Tc Tc duy tr ti a u tin lu lng Tc duy tr ti a u tin lu lng

Lung audio hoc video

Thoi vi d tm hot ng

Giao thc truyn file (FTP) Truyn d liu, duyt Web

H Cng Ngh - HQGHN

T-VT

c/ Qun l di ng C ba phng php chuyn giao c chun IEEE 802.16 h tr l : -

Chuyn giao cng (Hard Handoff HHO), Chuyn trm gc nhanh (Fast Base Station Switching FBSS) Chuyn giao phn tp v m (Macro Diversity Handover MDHO)

Trong , chuyn giao HHO l bt buc cn FBSS v MDHO l hai ch ty chn. Cng ging ging nh chuyn giao nhanh (FBSS hay MDHO) trong h thng CDMA, chuyn giao nhanh trong WiMAX cng ch c th thc hin gia cc BS nm trong ci gi l Diversity Set (tp hp cc BS hot ng trong cng tn s, c SINR ln MS c th kt ni c v c bit l chng phi ng b (synchronisation)). Trong Diversity Set ny th ch c 1 ci BS c gi l anchor (ci BS ch lc, hay cn gi l im kt ni, khp ). S khc nhau gia MDHO v FBSS l ch: i vi FBSS, MS ch communicate thng tin data thng qua BS anchor thi, cn MDHO th MS communicate thng tin data traffic qua tt c cc BS nm trong Diversity Set. d/ Bo mt WiMAX h tr tt nht cc c tnh bo mt lp nh p dng cc cng ngh tt nht ang sn c hin nay. N h tr nhn thc gia thit b/ngi dng, giao thc qun l kha linh ng, m ha lu lng, bo v bn tin iu khin v ti u ha giao thc bo mt cho cc chuyn giao nhanh. Giao thc qun l kha: Giao thc qun l kha v bo mt phin bn 2 (Privacy and Key Management Protocol Version 2 PKMv2) l mt trong nhng khi nim bo mt c bn ca WiMAX di ng. Giao thc ny qun l bo mt MAC s dng bn tin PKM REQ/RSP. Nhn thc PKM EAP, iu khin m ha lu lng, trao i kha chuyn giao v cc bn tin bo mt Mutilcast/Broadcast u da trn giao thc ny. Nhn thc thit b/ngi dng: WiMAX di ng h tr nhn thc thit b v ngi dng s dng giao thc IETF EAP bng cch cung cp h tr credentials c da trn SIM, hoc da trn USIM hoc chng nhn s hoc da trn tn ngi s dng/mt khu. M ha lu lng: AES-CCM l mt m ho c s dng bo v tt c s liu ngi s dng qua giao din WiMAX MAC di ng.______________________________________________________________________ 45 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

Bo v cc bn tin iu khin: D liu iu khin c bo v bi AES da trn CMAC, hoc s HMAC da trn MD5. H tr chuyn giao nhanh: Mt s bt tay 3 bc c h tr bi WiMAX di ng ti u c ch nhn thc li cho h tr chuyn vng nhanh. C ch ny cng hu ch trong vic chng li vic tn cng gia chng ca hacker. e/ Dch v Muticast v Broadcast MBS Dch v MBS trong WiMAX di ng kt hp cc c tnh tt nht ca DVB H, MediaFLO v 3GPP E UTRA, tha mn nhng yu cu sau: Tc d liu cao v kh nng ph sng s dng mng mt tn s (SFN Single Frequency Network) Cp pht ti nguyn v tuyn linh ng. MS tiu th nng lng thp. H tr d liu ngang hng bao gm cc lung audio v video. Thi gian chuyn mch knh nh.

2.2.5 Lp vt l (PHY, physical layer) Ban u c t PHY c nh ngha cho 1066 GHz l :Truyn lan LOS (line-ofsight -tm nhn khng b vt cn),Kin trc im- a im,v S dng iu bin sng n mang. khc phc hn ch truyn LOS trong di 10-66 GHz,Lp vt l 211 GHz c thit k do nhu cu theo hng hot ng NLOS (non-line-of-sight) v mi c t u a ra tnh hot ng cng nhau. V c bn, BS truyn mt tn hiu TDM vi nhng trm thu bao ring l c nh v nhng khe thi gian theo chu k. S truy cp theo hng ng ln cho bi TDMA. Tip theo nhng tho lun m rng v duplexing, mt thit k burst c chn cho php c TDD (timedivision duplexing), ti ng ln v ng xung dng chung mt knh nhng khng truyn cng lc v FDD (frequency-division duplexing), ti ng ln v ng xung hot ng trong nhng knh ring bit. Thit k burst ny cho php c TDD ln FDD c x l theo cch tng t. Nhng la chn mt trong hai TDD v FDD h tr nhng burst thch ng, trong nhng ty chn iu bin v m ha c th c gn ng trn c s tng burst mt. a\ nh dng khung c t PHY c nh ngha cho 1066 GHz s dng iu bin sng mng n dng burst vi burst-profiling thch ng, nhng tham s truyn, bao gm______________________________________________________________________ 46 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

H Cng Ngh - HQGHN

T-VT

cc k hoch iu bin v m ha, c th c iu chnh ring cho mi trm thu bao (subscriber station, SS) trn c s tng khung (frame) mt. H thng s dng mt khung 0.5, 1 hoc 2 ms. Khung ny c chia ra thnh nhng khe vt l cho mc ch cp pht v nhn bit di thng thuc cc chuyn tip PHY. Mt khe vt l c nh ngha cho 4 k hiu QAM (quadrature amplitude modulation). Trong phng n TDD ca PHY, khung con ca ng ln k tip theo khung con ca ng xung trong cng mt tn s sng mang. Trong phng n FDD, cc khung con ca ng ln v ng xung cui cng cng trng khp nhng chng c mang trn nhng tn s ring bit. Khung con ca ng xung bt u vi mt on iu khin khung c cha DL-MAP cho khung ng xung hin hnh cng nh UL-MAP cho thi gian nh r trong tng lai. Khung con ng xung c cha mt TDM-portion (on TDM) ngay tip theo on iu khin khung. D liu ng xung c truyn ti mi SS khi s dng mt burst-profile tha thun. Mo u khi u khung l dy 32 k hiu c to ra bng lp mt dy 16 k hiu .Khung iu khin chc nng c s dng chuyn thong tin iu kim cho knh ti tt c cc SS,v d liu ny khng c bo mt. Trong cc h thng, sau on TDM l mt on TDMA c cha mt on m du (preamble) ph ti im xut pht ca mi burst-profile mi. c tnh ny cho php h tr tt hn cc SS bn song cng. Trong mt h thng FDD c hoch nh hiu qu vi nhiu SS bn song cng, mt s c th truyn sm hn trong khung hn l chng nhn. V bn cht bn song cng, cc SS ny mt s ng b ha vi ng xung. TDMA-preamble cho php chng ly li s ng b ha . Type PHY Synchronization DCD Count BS_ID low BS_ID high Element count

Khun dng thng ip DL_MAP Type(8 bit) :kiu thng ip qun tr.c gi tr mc nh l 2. PHY Synchronization (32 bit):trng ng b vt l DCD Count (8 bit) :b m DCD Base station _ID low (32bit) :m nhn dng BS thp Base station _ID high (16bit) :m nhn dng BS cao Element count (16 bit) s lng phn t DL_MAP


H Cng Ngh - HQGHN

T-VT

DL-MAP ca on iu khin khung cung cp ti cc SS cc c tuyn cu ng xung. lun c th ng dng cho khung hin thi v lun c di ti thiu l hai block FEC. S chuyn tip PHY u tin c biu th trong block FEC u tin, cho php thi gian x l thch ng. Trong c hai h thng TDD v FDD, ULMAP cung cp cc nh v bt u khng mun hn khung ng xung tip theo. Tuy vy, UL-MAP c th nh v s khi u khung hin thi min l nhng thi gian x l v nhng tr ton phn (round-trip delay) phi c gim st. Type DL Ch_ID CCC PTR

Khun dng thng ip DCD Type: (8 bit) kiu thng ip qun tr c gi tr =1 DL Ch_ID : Downlink Channel ID (8 bit) ch th knh ng xung CCC (8 bit) :b m thay i cu hnh PTR (16 bt):trng con tr nh dng cu trc c trng vt l cho knh ng xung.

DCD l thng ip m t knh ng xung .mt b nhn dng BS 48 bit c th lp trnh trong DL_MAP. B nhn dng ny v DCD dng nhn dng knh ,c s dng trong trng hp khi SS nm trn ng bao vng ph sng. Type UL Ch_ID UCD count Element Allocation count start time

Khun dng thng ip DL_MAP Type: (8 bit) kiu thng ip qun tr c gi tr =3 UL Ch_ID : Uplink Channel ID (8 bit) ch th knh ng ln UCD count: (8 bit) b m UDC Element count: (16 bit) s lng phn t UL_MAP Allocation start time(32 bit) :thi im bt u phn phi

Khun dng thng ip UCD Type UL Ch_ID CCC RngBS RngBE ReqBS ReqBE PHY_Ptr List_Ptr Type: (8 bit) kiu thng ip qun tr c gi tr =0 UL Ch_ID : Uplink Channel ID (8 bit) ch th knh ng ln CCC (8 bit) :b m thay i cu hnh RngBS (8bit) im bt u sp xp RngBE (8bit) im kt thc sp xp


H Cng Ngh - HQGHN

T-VT

-

ReqBS (8bit) im bt u gi yu cu ReqBE (8bit) im kt thcgi yu cu PHY_Ptr (16 bt):trng con tr nh dng cu trc c trng vt l cho knh ng xung. List_Ptr (16 bt):trng m t kiu con tr nh dng cc loi burst.

UDC c s dng cung cp cho cc SS thng tin v yu cu c ch cum ng ln.Thng tin UL_MAP nhn c bng vic s dng b nhn dng kt ni CID. Thng ip ny cung cp mt m s dng xung nhp ng ln UIUC c SS s dng truyn ln. Thng ip UL_MAP v UCD c m t nh hnh trn. Khung con ng ln Khng ging nh ng xung, UL-MAP cp gii thng cho cc SS c th. Cc SS truyn trong vng cp pht c n nh c s dng burst-profile ch r bi UIUC (Uplink Interval Usage Code) trong mc vo (entry) UL-MAP cp di thng cho chng. Khung con ng ln c th cng cha nhng nh v trn c s cnh tranh cho truy nhp h thng lc ban u v broadcast hay multicast cc yu cu di thng. Nhng c hi truy cp cho truy nhp h thng lc ban u c xc nh ln cho php thm thi gian bo v cc SS m chng khng c gii quyt thi gian truyn cn thit b li tr ton phn (round-trip delay) cho BS. C 3 loi cm c th hin din trong bt k khung con ng ln no : -

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Cm tranh chp :da trn duy tr ban u hoc cc c hi truy nhp ban u Cm tranh chp da trn c hi mc dnh bng khong thi gian yu cu p ng truyn a hng hoc vng qung b Khng tranh chp da trn nh v khong thi gian c sp xp ti SS c bit trong UL_MAP m bo bng thng t BS

Cc cm trn u c th c trong bt k khung no.Khng ging nh UL_MAP cp bng thng cho cc SS c th. Khung con ng ln c th cha cc nh v trn c s tranh chp cho truy nhp h thng lc ban u. b\Lp con hi t truyn TC (transmission convergence). Gia PHY v MAC l mt lp con hi t truyn TC (transmission convergence). Lp ny thc hin s bin i cc PDU (protocol data units) MAC di c th thay i vo trong cc block FEC di c nh (cng thm c th l mt block c rt ngn vo on cui) ca mi burst. Lp TC c mt PDU c kch thc khp vi block FEC hin thi b y. N bt u vi mt con tr ch ra v tr u mc PDU MAC tip theo bt u bn trong block FEC. Khun dng PDU_TC P(con tr Khi PDU u tin Khi PDU u tin Khi PDU th 2 1byte) khi u trong TC khi u trong TC khi u trong 49 ______________________________________________________________________TC Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam hin ti ngay trc hin ti

H Cng Ngh - HQGHN

T-VT

Khun dng PDU TC cho php ng b ha li PDU MAC tip sau trong trng hp block FEC trc c nhng li khng th phc hi c. Khng c lp TC, mt SS hay BS nhn s mt ton b phn cn li ca mt burst khi mt li khng th sa cha xut hin. 2.2.6 Cc k thut truyn thng s trn lp PHY a/ OFDM (Orthogonal Frequency Division Multiplexing) hay ghp knh phn chia theo tn s trc giao l mt k thut iu ch a sng mang. K thut ny c th t c tc d liu rt cao, chng nhiu giao thoa k t - ISI (Inter symbol Interference) v gii quyt c vn tn hiu a ng. Cng ngh OFDM chia lung d liu thnh nhiu ng truyn bng hp trong vng tn s s dng cc sng mang con trc giao vi mt sng mang con khc. Nhng sng mang con ny sau ghp thnh cc knh tn s truyn v tuyn. OFDM khai thc s phn tp tn s ca knh a ng bng cch m ho v chn thng tin trn cc sng mang con trc khi truyn i. iu ch OFDM c th thc hin c vi bin i ngc Fourier nhanh - IFFT, php bin i ny cho php mt s lng ln cc sng mang con (ln ti 2048) vi phc tp thp. Trong mt h thng OFDM, ti nguyn sn c trong min thi gian chnh l cc symbol OFDM v trong min tn s chnh l cc sng mang con. Ti nguyn v thi gian v tn s c th c t chc thnh cc knh con (sub-channel) cp pht cho ngi dng. b/OFDMA (Orthogonal Frequency Division Multiple Access)- a truy nhp phn chia theo tn s trc giao l cng ngh a truy cp phn chia theo sng mang , v c pht trin da trn cng ngh OFDM. OFDMA cho php nhiu ngi dng cng truy cp vo mt knh truyn bng cch phn chia mt nhm cc sng mang con (subcarrier) cho mt ngi dng ti mt thi im. cc thi im khc nhau, nhm sng mang con cho 1 ngi dng cng khc nhau. OFDMA c dng trong cng ngh mng 802.16e (WiMAX di ng), OFDMA h tr cc nhim v ca cc sng mang con i vi cc thu bao nht nh. Mi mt nhm sng mang con c biu th nh mt knh con (subchannel) v mi thu bao c ch nh mt hoc nhiu knh con truyn pht da trn mi yu cu c th lu lng ca mi thu bao


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OFDMA c mt s u im nh kh nng linh hot tng, thng lng v tnh n nh c ci tin. Bng vic n nh cc knh con cho cc thu bao c th, vic truyn pht t mt s thu bao c th xy ra ng thi m khng cn s can thip no, do s gim thiu tc ng nh nh hng a truy nhp. c/ Cc h thng anten thch ghi AAS (Adaptive Antena System) Cc h thng anten thch ghi AAS (Adaptive Antena System) l mt phn ca la chn tiu chun IEEE 802.16. AAS c kh nng iu chnh bp sng ch tp trung vo mt hng nht nh hoc cng c th tp trung vo nhiu hng. iu ny c ngha l trong khi pht tn hiu c gii hn theo mt hng nht nh ca pha thu, ging nh mt im sng. Cn khi thu, h thng AAS cng c kh nng gim nhiu ng knh t cc v tr khc. AAS c coi l s pht trin ca tng lai, c kh nng ci thin t l ti s dng ph tn v kh nng ca mt mng WiMAX d/MIMO- Multiple-Input and Multiple-Output La chn phn tp pht WiMAX s dng m ha thi gian khng gian, lm gim qu d tr yu cu v trnh nhiu. i vi phn tp pht, rt nhiu cc phng php kt hp ci thin kh nng ca h thng. M khng gian thi gian (Space Time Code STC): H tr phn tp truyn nh m Alamouti cung cp kh nng phn tp khng gian v gim d tr suy hao tn hiu. Ghp knh khng gian (SM): H tr ghp knh khng gian tn dng tc nh cao hn v gim thng lng. Nh ghp knh khng gian, nhiu lung s c truyn trn h thng nhiu anten. Nu pha thu cng c h thng nhiu anten, n c th phn tch cc lung khc nhau t c thng lng cao hn so vi cc h thng n anten. e/iu ch thch nghi v m ha(AMC- Adaptive Modulation and Coding) iu ch thch nghi cho php h thng WiMAX iu chnh c phng php iu ch tn hiu da trn iu kin SNR ca tuyn. Khi tuyn truyn dn c cht lng tt, kiu iu ch cao nht c s dng, lm tng dung lng ca h thng. Khi tuyn mc cht lng thp hn, h thng WiMAX c th chuyn sang mt kiu iu ch thp hn m bo cht lng kt ni v n nh ca tuyn. Ngoi ra iu ch BPSK cng c dng gi cc thng bo tn hiu (signalling), broadcast...trong h thng WiMAX v n cho 1 vng ph ln nht.______________________________________________________________________ 51 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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f/ K thut sa li trc (FEC-forward error correction) Cc k thut sa li trc c p dng trong h thng WiMAX gim t s tn hiu trn tp m yu cu. M ha sa li trc (FEC) Reed Solomon, m ha xon cc thut ton chn k t c s dng pht hin v sa li nhm ci thin thng lng ca h thng. g/ S dng li tn s c bit trong WiMAX, l dy tn s dng trn 2 cells k nhau l nh nhau. V trong WiMAX s dng OFDMA, v mi mt user s c phn b mt s tn s v symbol time nht nh (gi l zone/chunk). Nh th trnh nhiu th cc user ba ca nhng cell gn nhau s c phn b cc tn s khc nhau. chnh l khi nim chia nh tn s (fractional freq reuse).

Hnh 10: Minh ha cc loi iu ch dng trong WiMAX h/. T ng yu cu lp li kiu kt hp(HARQ- Hybrid automatic repeat request) WiMAX di ng cng h tr HARQ. HARQ c php s dng giao thc Dng v i N knh cung cp kh nng p ng nhanh ng gi li v ci tin kh nng ph sng ng bin cell. Ngoi ra ci thin hn na s n nh ca ng truyn. Mt knh dnh ring ACK cng c cung cp ng ln bo hiu ACK/NACK ca HARQ. Hot ng a knh HARQ cng c h tr. 2.3 Cu hnh mng______________________________________________________________________ 52 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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WiMAX h tr cu hnh mng a im v cu hnh mng li MESH 2.3.1Cu hnh im-a im PMP PMP l mt mng truy nhp vi mt hoc nhiu BS c cng sut ln v nhiu SS nh hn. Ngi dng c th ngay lp tc truy nhp mng ch sau khi lp t thit b ngi dng. SS c th s dng cc anten tnh hng n cc BS, cc BS c th c nhiu anten c hng tc dng theo mi hng hay mt cung. Vi cu hnh ny trm gc BS l im trung tm cho cc trm thu bao SS. hng DL c th l qung b, a im hay n im. Kt ni ca mt SS n BS c c trng qua nhn dng kt ni CID.

Hnh 11 Cu hnh PMP 2.3.2 Cu hnh mt li MESH Vi cu hnh ny SS c th lin lc trc tip vi nhau. Trm gc Mesh BS kt ni vi mt mng bn ngoi mng MESH. Mt s im phn bit nh sau: Neighbor: Kt ni trc tip n mt node mng Neighborhood : Tt c cc neighbor ca mt node to ra neighorhood. Extended neighborhood: Tt c cc neighbor ca mt neighborhood.

MESH khc PMP l trong kiu PMP cc SS ch lin h vi BS v tt c lu lng i qua BS.Vi kiu MESH tt c cc node c th lin lc vi mi node khc mt cch trc tip hoc bng nh tuyn nhiu bc thng qua cc SS khc.______________________________________________________________________ 53 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Mt h thng vi truy nhp n mt kt ni backhaul c gi l Mesh BS, trong khi cc h thng cn li c gi l Mesh SS. D cho MESH c mt h thng c gi l Mesh BS, h thng ny cng phi phi hp qung b vi cc node khc. Backhaul l cc anten im-im c dng kt ni cc BS c nh v qua khong cch xa.

Hnh 12 Cu hnh mesh Mt mng MESH c th s dng hai loi lp lch qung b. Vi kiu lp lch phn tn, cc h thng trong phm vi hai bc ca mi node khc nhau chia s cc danh mc v hp tc m bo trnh xung t v chp nhn ti nguyn. MESH lp lch tp trung da vo Mesh BS tp hp cc yu cu ti nguyn t cc Mesh SS trong mt di bt k v phn phi cc yu cu ny vi kh nng c th. Kh nng ny c chia s vi cc Mesh SS khc m d liu ca ngi dng c chuyn tip thng qua cc Mesh SS trao i vi Mesh BS. Trong kiu MESH, phn loi QoS c thc hin trn nn tng tng gi hn l c kt hp vi cc lin kt nh trong kiu PMP. Do ch c mt lin kt gia gia hai node Mesh lin lc vi nhau. 2.4 Kin trc mng WIMAX


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Hnh 13 M hnh truyn thng ca WiMAX WiMAX hot ng tng t WiFi nhng tc cao v khong cch ln hn rt nhiu cng vi mt s lng ln ngi dng. Mt h thng WiMAX gm 2 phn:-

Trm pht: ging nh cc trm BTS trong mng thng tin di ng vi cng sut ln c th ph sng mt vng rng ti 8000km2 Trm thu: c th l cc anten nh nh cc Card mng cm vo hoc c thit lp sn trn Mainboard bn trong cc my tnh, theo cch m WiFi vn dngCc trm pht BTS c kt ni ti mng Internet thng qua cc ng truyn tc cao dnh ring hoc c th c ni ti mt BTS khc nh mt trn trung chuyn bng ng truyn thng (line of sight), v chnh v vy WiMAX c th ph sng n nhng vng rt xa.

Cc anten thu/pht c th trao i thng tin vi nhau qua cc tia sng truyn thng hoc cc tia phn x. Trong trng hp truyn thng, cc anten c t c nh trn cc im cao, tn hiu trong trng hp ny n nh v tc truyn c th t ti a. Bng tn s dng c th dng tn s cao n 66GHz v tn s ny tn hiu t b giao thoa vi cc knh tn hiu khc v bng thng s dng cng ln hn. i vi trng hp tia phn x, WiMAX s dng bng tn thp hn, 2-11GHz,______________________________________________________________________ 55 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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tng t nh WiFi, tn s thp tn hiu d dng vt qua cc vt cn, c th phn x, nhiu x, un cong, vng qua cc vt th n ch. WiMAX Forum nh ngha mt modul tham chiu mng WiMAX (NRM). NRM nhn dng cc thc th chc nng v cc im tham chiu qua tnh tng tc t c gia cc thc th chc nng Nhiu ASN ca cng mt operator to thnh mt NAP (Network Access Provider). Nhiu nh cung cp khc nhau s c th trin khai nhiu mng truy nhp khc nhau, ri chng s cng kt ni vi mt hoc nhiu CSN (Core Service Network).

Hnh 14:Cc im tham chiu trong mng WiMAX Hnh v sau cung cp mt ci nhn c th hn v nhiu thc th trong cc nhm chc nng ca ASN v CSN.


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Hnh 15 :Cc thc th v nhm chc nng trong mng CSN c nh ngha l mt tp cc chc nng mng cung cp cc dch v kt ni IP cho cc thu bao WiMAX. Mt CSN c th gm cc phn t mng nh router (b nh tuyn), my ch/proxy nhn thc AAA, c s d liu ngi dng v thit b cng lin mng. Mt CSN c th c trin khai nh mt phn ca nh cung cp dch v mng WiMAX. MS, ASN, CSN v cc im tham chiu c nhn dng mt cch r rng cho lin kt ca cc thc th logic. Cc im tham chiu miu t mt nhm cc chc nng.. Vic to nhm v phn phi cc chc nng trong cc thit b vt l, trong mt thc th chc nng (nh ASN) l mt la chn b sung. Mt nh sn xut c th chn bt k b sung cc chc nng vt l no, ring bit hoc kt hp, vi iu kin vic b sung p ng cc yu cu v tnh tng tc v v chc nng. Mc tiu ca NRM l cho php nhiu ty chn b sung cc chc nng xc nh, v phi c tnh tng tc gia cc thc th chc nng khc nhau. Tnh tng tc da trn nh ngha cc giao thc truyn thng v cch x l mt bng d liu gia cc thc th chc nng t c mt chc nng u cui-u cui hon thin, v d, bo mt hay qun l tnh di ng. Do , cc thc th chc nng pha ny hay pha kia ca mt im tham chiu miu t mt tp hp cc im cui mt bng iu khin v truyn ti. Cc giao din ny nh ngha cc th tc v cc giao thc v cc lin kt logic, lin kt vt l truy nhp cc thc th.Cc chi tit k thut ca mng cho h thng WiMAX da trn c s nhiu nguyn l kin trc mng c bn, c lit k di______________________________________________________________________ 57 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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y. Mt s cc nguyn l chung c hng dn trin khai kin trc mng WiMAX di ng bao gm: - Cung cp s tch bit v mt logic gia cc th tc ni trn v nh a ch IP, nh tuyn v th tc qun l kt ni v cc giao thc cho php s dng kin trc truy nhp c bn trong cc trng hp trin khai tng thch v mt mnh. - H tr chia s mt hay nhiu ASN ca mt NAP gia nhiu NSP. - H tr dch v cung cp NSP n l qua nhiu ASN c qun l bi mt hay nhiu NAP. - H tr vic pht hin v la chn cc NSP c th truy nhp bi mt MS hay SS. - H tr cc NAP m s dng mt hay nhiu cu hnh ASN. - H tr truy nhp n cc dch v ca nh khai thc hin thi thng qua tng thch cc chc nng khi cn thit. - Chi tit k thut ca cc im tham chiu khng hn ch v hon ton xc nh gia mt nhm cc thc th chc nng mng (trong mt ASN, gia cc ASN, gia mt ASN v mt CSN v gia cc CSN) v c bit gia mt MS, ASN v CSN cho php tng tc gia nhiu nh cung cp. - H tr cc phng php nng cp gia nhiu kiu thng dng thnh cc gi nh v bt buc hp l v mt cng ngh. - Cho php b sung cc nh cung cp khc nhau trn c s kt hp cc thc th chc nng khc nhau trn cc thc th mng vt l, vi iu kin nhng b sung ny tun theo cc giao thc v th tc quy chun qua cc im tham chiu thch hp, nh nh ngha trong c im k thut mng. - H tr cho trng hp mt nh khai thc ring l bnh thng nht s dng mt ASN cng vi mt t hp c gii hn cc chc nng CSN, v th nh khai thc c th a ra dch v truy cp Internet c bn m khng xem xt v Roaming hay tng thch. 2.4.1 Qu trnh vo mng Mt trm thu bao WiMAX phi hon thnh th tc vo mng lin lc c vi mng. Trng thi vo mng thay i thit lp li nu n b li tip tc t bt k trng thi no. ng b knh ng xung Khi SS mun vo mng, n qut mt knh trong danh sch tn s nh ngha. Thng thng mt SS c cu hnh s dng mt BS c th vi mt t hp cho trc cc tham s vn hnh, khi hot ng trong bng tn c cp php. Nu SS tm thy mt knh ng xung v c th ng b mc vt l s dng______________________________________________________________________ 58 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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mo u chu k khung. Thng tin v iu ch v cc tham s UL v DL khc ginh c bng cch quan st DCD v UCD ca knh ng xung. Initial Ranging Khi mt SS c ng b vi knh DL v nhn DL v UL-MAP cho mt khung, n bt u th tc Initial Ranging bng cch gi mt bn tin MAC yu cu Ranging s dng cng sut truyn dn cc tiu. Nu khng nhn c tr li t BS, SS gi li bn tin trn mt khung k tip s dng cng sut truyn dn cao hn. Cui cng l SS nhn mt tr li Ranging.Tr li th hin cng sut v nhng hiu chnh nh thi m SS phi lm hoc th hin s thnh cng. Nu tr li ch th hiu chnh, SS phi lm cc hiu chnh ny v gi mt yu cu Ranging khc. Nu tr li ch th thnh cng, SS sn sng gi d liu ng ln. Trao i cc kh nng Sau khi hong thnh bc Initial Ranging thnh cng, SS gi bn tin yu cu kh nng cho BS miu t kh nng ca n v mc iu ch, lc m ha v tc , phng php song cng c h tr. BS chp nhn hoc t chi SS da vo kh nng ca n. Nhn thc Sau khi thng lng kh nng, BS nhn thc SS, v cung cp vt liu kha cho php mt m d liu. SS gi chng nhn X.509 ca nh sn xut SS v miu t cc thut ton mt m ha c h tr cho BS ca n. BS ph chun nhn dng ca SS, quyt nh thut ton mt m v giao thc c s dng sau gi mt bn tin tr l nhn thc cho SS. Tr li cha vt liu kha c s dng bi SS. SS c yu cu thc hin nh k th tc nhn thc v trao i kha lm mi vt liu kha ca n. ng k Sau khi nhn thc, SS gi mt bn tin yu cu ng k cho BS v BS gi tr li ng k ti SS. Trao i ng k bao gm h tr phin bn IP, h tr SS c qun l hoc khng c qun l, h tr cc tham s ARQ, h tr cc ty chn phn loi, h tr CRC v iu khin lung. Kt ni Sau khi ng k, SS khi ng DHCP (IETF RFC 2131) nhn c a ch IP v cc tham s khc thit lp kt ni IP. BS v SS duy tr ngy gi hin ti s______________________________________________________________________ 59 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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dng giao thc the time of the day (IETF RFC 868). SS cng ti v cc tham s sn sng cho vic hot ng s dng TFTP (IETF RFC 1350).

Hnh 16 : Qu trnh vo mng To kt ni truyn ti Sau khi hon thnh ng k v trao i cc tham s vn hnh, cc kt ni truyn ti c to ra. Vi cc lung dch v c d tr trc, th tc to kt ni c khi u bi BS. BS gi mt bn tin yu cu thm lung dch v ng cho SS v SS xc nhn vic to kt ni. Vi cc lung dch v khng d tr trc, to kt ni c khi to bi SS bng cch gi mt bn tin yu cu thm lung dch v ng cho BS. BS tr li vi mt xc nhn. 2.4.2 Mt s nguyn l c bn trong trin khai mng WiMAX: 1. Kin trc mng da trn c cu chuyn mch gi, bao gm cc th tc da trn chun IEEE 802.16 v cc sa i ca n, cc chun IETF v Ethernet ph hp.


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2. Kin trc mng cho php tch ring kin trc truy nhp (v h tr cc cu hnh) t dch v kt ni IP. Cc phn t mng ca h thng kt ni khng nhn bit v cc chi tit v tuyn IEEE 802.16. 3. Kin trc mng cho php tnh modul v linh ng cung cp mt di rn cc ty chn nh: Mng WiMAX t quy m nh n quy m ln. Cc bng tn v tuyn vng nng thn, ngoi v thnh th Cc cu hnh c th bc, bng phng hoc Mesh v cc bin th ca chng. Cc kiu c nh, mang xch v di ng cng tn ti

2.4.3 Cc dch v v cc ng dng c h tr trong WiMAX. 1. Cc dch v thoi, a phng tin v cc dch v iu tit c y quyn khc nh dch v khn v ngn chn hp php. 2. Truy nhp n nhiu mng ca nh cung cp dch v ng dng (ASP) c lp theo kiu khng nhn bit. 3. Truyn thng in thoi di ng s dng VoIP. 4. H tr giao din vi nhiu cng tng thch v media cho php vic pht cc dch v hin thi/ k tha truyn qua IP (v d SMS qua IP, MMS, WAP) truy nhp mng WiMAX. 5. H tr vic pht cc dch v qung b v a im qua mng truy nhp WiMAX.2.5 Nhng u im v mi trng ng dng ca WiMAX

2.5.1 u im C s quan trng ca cng ngh WiMAX l s tng thch ca thit b WiMAX, c Din n WiMAX chng nhn, to s tin cy v lm tng s lng ln cho nh cung cp dch v khi mua thit b khng ch t 1 cng ty v tt c u tng thch vi nhau. Din n WiMAX ln u tin t hp nhng cng ty hng u trong ngnh truyn thng v my tnh to nn mt nn tng chung cho vic trin khai cc dch v v tuyn bng rng IP trn ton cu.Ngoi ra cn cc c s quan trng khc l : Chi ph thp hn CPE v tuyn c nh c th s dng cng loi chipset modem c s dng trong my tnh c nhn (PC) v PDA, v khong cch gn cc modem c th t lp t trong nh CPE s tng t nh cp, DSL v cc trm gc c th s dng cng loi chipset chung c thit k cho cc im truy cp WiMAX chi ph thp v cui cng l s lng tng cng tha mn cho vic u t vo vic tch hp mc cao hn cc chipset tn s v tuyn (RF), lm chi ph gim hn na.______________________________________________________________________ 61 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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bao ph rng hn Cng ngh sau WiMAX c ti u mang n bao ph NLOS tt nht. Cc u im ca NLOS l bao ph trn din rng, kh nng d bo bao ph tt hn v chi ph thp hn c ngha l s trm gc v backhaul t hn, nh c RF n gin, cc thi im lp t thp ngn hn v lp t CPE nhanh hn. Nh c cc k thut ci tin bao ph NLOS nh phn tp, m ha thi gian khng gian v yu cu truyn li t ng (Automatic Retransmission Request ARQ), cc khong cch bao ph s c tng ln. Cng sut cao hn u im quan trng ca WiMAX l s dng k thut OFDM (Orthogonal Frequency Division Multiplexing) qua cc c ch iu ch n sng mang vi kh nng cung cp hiu sut bng thng cao hn v do thng lng d liu cao hn vi lung xung hn 1Mbit/s v thm ch cc tc d liu cao hn nhiu d trong NLOS vi cc iu kin a ng. iu ch thch ng (Adaptive Modulation) cng lm tng tin cy ng kt ni i vi hot ng phn loi sng mang v kh nng gi iu ch 64QAM khong cch rng hn, tng cng sut qua cc khong cch di hn Chun cho truy cp v tuyn c nh v di ng WiMAX s tr thnh mt gii php chi ph hp l nht cho cc nh khai thc trin khai cc ng dng v tuyn c nh v di ng cho cc my xch tay v PDA. Din n WiMAX s chng nhn cc sn phm tun th v tng thch da trn cc chun 802.16 ca IEEE v HiperMAN ca ETSI. Li ch ca doanh nghip v ngi s dng h gia nh i vi cc doanh nghip, WiMAX cho php truy cp bng rng vi chi ph hp l. V phn ln cc doanh nghip s khng c chia thnh khu vc c ng cp, la chn duy nht ca h i vi dch v bng rng l t cc nh cung cp vin thng a phng. iu ny dn ti s c quyn. Cc doanh nghip s c hng li t vic trin khai cc h thng WiMAX chng nhn nh to ra s cnh tranh mi trn th trng, gim gi v cho php cc doanh nghip thit lp mng ring ca mnh. iu ny c bit ph hp i vi cc ngnh nh kh t, m, nng nghip, vn ti, xy dng v cc ngnh khc nm nhng v tr xa xi, ho lnh.


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i vi ngi s dng l h gia nh nhng vng nng thn (ni dch v DSL v cp cha th vn ti), WiMAX mang li kh nng truy cp bng rng. iu ny c bit ph hp cc nc ang pht trin ni m h tng vin thng truyn thng vn cha th tip cn 2.5.2 Mi trng ng dng ca WiMAX WiMAX vi th mnh l ph sng rng, khng cn c vo a hnh bng phng hay him tr, ph hp cho vic ph cp Internet bng thng rng ti mi min t nc, k c cc vng su, vng xa. WiMAX c coi l cng ngh l tng cho ton b khu vc ng Nam , gip cc nc trong khu vc thc hin cc mc tiu cp thit nh chnh ph in t, pht trin gio dc, y t, nng nghip... Mt mng MAN khng dy da trn chun giao din khng gian WiMAX c cu hnh theo cng mt cch nh mt mng t bo truyn thng vi chin lc nh v trm gc BS s dng mt kin trc PMP phn pht cc dch v qua mt bn knh ln n vi km ty thuc vo tn s, cng sut pht v nhy u thu. Trong cc vng vi mt dn c cao, phm vi thng s b hn ch hn gii hn do lng ph sn c. Cc BS theo tiu chun c backhaul n mng li bng phng tin si hay cc lin kt sng vi ba im-im n cc node si c sn hay thng qua cc ng dy cho thu t mt nh khai thc hu tuyn hin thi. Phm vi v kkh nng NLOS lm cho cng ngh ny tr nn hp dn c mang li li nhun trong nhiu loi mi trng rng ln. Cng ngh ny c hnh dung ban u nh mt phng tin cung cp truy nhp bng rng chng cui (last mile) khng dy trong cc mng MAN vi hiu sut v cc dch v c th bng hoc tt hn DSL truyn thng, cp hay cc dch v ng dy cho thu T1/E1. Ngy nay th trng ny ch yu ph thuc vo tnh sn c ca DSL hay cp. Mt s vng m cc dch v c sn khng p ng s mong i ca khch hng v hiu nng hay tin cy v gi c qu cao. Trong nhiu vng nng thn th khch hng b hn ch v cc dch v quay s tc thp. Trong cc nc ang pht trin c nhiu vng khng c cc phng tin sn c truy nhp Internet. Cng ngh WiMAX s cho php mt nh khai thc tp trung v mt kinh t vo loi th trng ny v c mt iu kin kinh doanh thun li di mt s a dng ca cc iu kin con ngi. a\ Cc nh kinh doanh va v nh Loi th trng ny thng l rt nh trong cc vng khng phi cc mi trng thnh th cnh tranh mc cao. Cng ngh WiMAX c th mang li li nhun khi p ng cc nhu cu ca cc nh kinh doanh va v nh trong cc mi______________________________________________________________________ 63 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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trng mt thp v cng c th cung cp mt chn la c li trong cc mi trng thnh th cnh tranh vi DSL v cc dch v ng dy thu. b\ Backhaul im nng Wi-fi Cc im nng Wifi c lp t trn khp th gii mt tc cao. Tuy nhin,mt trong nhng tr ngi cho vic tip tc pht trin im nng l tnh sn sng ca cc gii php Backhaul dung lng cao, c nhiu li ch. ng dng ny cng c th c tp trung vi cng ngh WiMAX. V vi kh nng di ng, WiMAX cng c th lp y khong trng gia cc vng bao ph im nng Wi-fi.

Hnh17 :cc Mi trng ng dng ca WiMAX c\ Backhaul mng t bo Phn ln backhaul c thc hin bng cch thu cc dch v T1/E1 t cc nh khai thc hu tuyn hin thi hoc s dng sng vi ba im-im thng dng hn cho mng t bo di ng, nhng WiMAX c th hot ng ng vai tr trong vic cho php cc nh khai thc di ng tng mt cch c li kh nng backhaul s dng WiMAX nh mt mng bao ph. Phng php bao ph ny s cho php cc nh khai thc di ng thm kh nng yu cu h tr phm vi ln cc dch v di______________________________________________________________________ 64 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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ng mi m h ln k hoch ngh khng c s ri ro ca vic ph hy cc dch v ang tn ti. Trong nhiu trng hp ng dng ny s c tp trung mt cch tt nht thng qua 801.16 da trn cc lin kt im-im chia s vi h thng PMP. d\ Cc dch v an ton cng cng v cc mng ring H tr cho cc dch v di dng v kh nng cung cp bao ph khp ni trong mt vng thnh th , cung cp mt cng c thi hnh lut l, bo v cao v cc cu to an ton cng cng khc cho php chng duy tr truyn thng quan trng trong cc iu kin bt li khc nhau. Cc mng ring cho cc ngnh cng nghip phc tp, cc trng i hc v cc loi mi trng khc cng u l mt c hi kinh doanh tim nng cho WiMAX. Cng ngh WiMAX l gii php cho nhiu loi ng dng bng rng tc cao cng thi im vi khong cch xa v cho php cc nh khai thc dch v hi t tt c trn mng IP cung cp cc dch v "3 cung": d liu, thoi v video. WiMAX vi s h tr QoS, kh nng vn di v cng sut d liu cao c dnh cho cc ng dng truy cp bng rng c nh nhng vng xa xi, ho lnh, nht l khi khong cch l qu ln i vi DSL v cp cng nh cho cc khu vc thnh th cc nc ang pht trin. Nhng ng dng cho h dn gm c Internet tc cao, thoi qua IP, video lung/chi game trc tuyn cng vi cc ng dng cng thm cho doanh nghip nh hi ngh video v gim st video, mng ring o bo mt (yu cu an ninh cao). Cng ngh WiMAX cho php bao trm cc ng dng vi yu cu bng thng rng hn. WiMAX cng cho php cc ng dng truy cp xch tay, vi s hp nht trong cc my tnh xch tay v PDA, cho php cc khu vc ni th v thnh ph tr thnh nhng "khu vc din rng" ngha l c th truy cp v tuyn bng rng ngoi tri. Do vy, WiMAX l mt cng ngh b sung bnh thng cho cc mng di ng v cung cp bng thng ln hn v cho cc mng Wi-Fi nh cung cp kt ni bng rng cc khu vcln hn. 2.6 So snh gia Wi-Fi v WiMAX[4] S khc nhau c bn nht gia WiMAX v Wi-fi l chng c thit k cho cc ng dng hon ton khc nhau. Wi-Fi l mt cng ngh mng vng ni ht LAN c thit k tng thm tnh di ng cho cc mng LAN hu tuyn ring. WiMAX mt mt khc c thit k cung cp mt dch v truy nhp khng dy bng rng (BWA) cho mng vng thnh th MAN. V th trong khi Wi-Fi h tr truyn dn trong phm vi hn trm mt th WiMAX c th h tr cc ngi dng trong bn knh ti hng chc kilmt.______________________________________________________________________ 65 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Bn cnh s khc nhau v phm vi truyn dn, mt s ci thin v cng ngh lien kt v tuyn l khc nhau gia WiMAX v Wi-Fi. Chun IEEE802.11 WLAN miu t bn giao din lin kt v tuyn hot ng trong bng tn v tuyn khng cp php 2.4 hoc 5GHz. Cc chun WiMAX bao gm mt di rng hn cc b sung tim nng gii quyt cc yu cu ca cc sng mang khp th gii. Cc bng tn WiMAX s dng c bng tn cp php v khng cp php ch yu trong di t 2-11GHz Trong cc bng tn khng cp php, cc chun WiMAX kt hp c im la chn tn s ng nhng ni m sng v tuyn t dng tm kim mt knh cha s dng. Trong cc vng xa, nhiu c th c gim thiu. Trong khi vi WiMAX th knh ng ln v ng xung s dng k thut ghp knh phn chia theo thi gian TDD v ghp knh phn chia theo tn s FDD. Trong TDD vi khe thi gian c n nh cho ng ln v ng xung tch bit nhau v th knh truyn l song cng ton phn. Trong khi gim tc truyn 50% th cc h thng ny ch s dng mt na bng tn v tuyn so vi FDD. i vi Wi-Fi th tt c cc h thng Wi-Fi l cc h thng TDD trn c s tranh chp ni m im truy nhp v cc trm s dng chung mt knh. Bi v hot ng mi trng dng chung nn tt c mng Wi-Fi l bn song cng. Wi-Fi s dng hai cng ngh truyn dn v tuyn c bn. :802.11b: lin kt v tuyn s dng mt cng ngh tri ph tun t trc tip c gi l kha c m ha b sung (CCK). Sau lung bit c x l vi m c bit v sau c iu ch s dng QPSK. 802.11a v 802.11g s dng OFDM. u pht m ha lung bit trn 64 sng mang s dng BPSK, QPSK hay mt trong hai kiu 16-QAM, 64-QAM. Mt s thng tin c pht l khng cn thit, v th u thu khng phi nhn tt c cc sng mang con khi phc thng tin. WiMAX s dng cng ngh OFDM v OFDMA cho lp vt l lm tng quy m v tc cho mng. C WiMAX v Wi-Fi u s dng iu ch thch ng v nhiu mc hiu chnh li trc ti u ha tc truyn v hiu sut li. Khi mt tn hiu v tuyn gim cng sut hay c nhiu th t l li s tng. iu ch thch ng ngha l u pht s t ng thay i hiu sut tng ln hay thm ch gim i. C ch hiu chnh li trc FEC nhm khc phc bt li v ci thin hiu nng truyn dn. Tuy nhin lc u Wi-Fi vi chun 802.11b cha c FEC nhng______________________________________________________________________ 66 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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FEC m xon c kt hp trong 802.11a v 802.11g. WiMAX s dng c hai h thng FEC m xon v Reed-Solomon. Thuc tnh Kh nng Cht lng QoS

Wi-Fi (802.11)

WiMAX(802.16)

Phm vi

Ph sng Bo mt

- Knh c nh (20MHz) - Knh c bng tn thay i - MAC h tr hng chc ngi Kh nng m rng bng tn t s dng 1,5#20Mhz - MAC h tr hng trm ngi s dng - S dng (CSMA/CA) nn - C m bo v cht lng trn MAC khng m bo v cht lng -H tr m thanh,hnh nh - Hin ti khng h tr m - H tr nhiu mc dch v T1 cho thanh,video ngi bun bn, c bit hiu qu nh - Khng cho php cc mc dch ring v khc nhau - C TDD/FDD/HFDD (c i xng v - Ch c TDD (bt i xng) bt i xng) - Ch 802.11e u tin cho QoS - Yu cu bt buc cho QoS - Ti u khong 100 m -Ti u ho khng 50km - Khng c kh nng b khong - Thit k cho nhiu ngi s dng cch hng km - Thit k a ng trong nh - Chu c tr a ng ln c 10 ms (tr 0,8ms) - Lp PHY v MAC vi kh nng m -Ti u ho tp trung ti hai lp rng trong phm vi cho php PHY v MAC trong phm vi - MAC chun tc 100m - M rng phm vi nh thay i cng sut nhng lp MAC c th khng chun tc - Ti u ho trong nh - Ti u ho bn ngoi trong tm nhn - Khng h tr mng cu hnh hn ch pha trn - H tr cu hnh mng pha trn - H tr k thut anten thng minh - Chun ang tn ti l WPA v - C kho b ba DES (128 bit) v WEP RSA(1024 bit - 802.11i c ch bo mt a ch Bng 7: So snh WiMAX v WiFi

Bn cnh trong WiMAX c h tr nhiu cng ngh v tuyn hin i nh cc anten thng minh c th lm gim thiu nhiu v nng cao tc truyn. Kt hp vi tnh a dng u pht, a dng u thu MIMO ci thin phm vi bao______________________________________________________________________ 67 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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ph. Tc truyn d liu c h tr cho WiMAX l rt cao, ln ti 100Mbps trong mt knh 20MHz trong tc c duy tr l 70Mbps. i vi Wi-Fi tc truyn c h tr ti a ch t 54Mbps. Lp MAC ca WiMAX v Wi-Fi hon ton khc nhau. i vi WiMAX th giao thc lp MAC c th chia s knh v tuyn gia hng trm ngi dng trong khi vn m bo QoS, WiMAX s dng k thut yu cu/ cp pht loi tr cc tranh chp ng ln h tr tr nht qun cho thoi v tr bin i cho cc dch v d liu. Giao thc MAC ca WiMAX cng c c im sa li s dng yu cu truyn li t ng ARQ. Ngc li trong Wi-Fi th giao thc lp MAC trn c s tranh chp. Giao thc MAC ca Wi-FI c gi l a truy nhp cm ng sng mang v trnh xung t (CSMA/CA). Trong khi WLAN l bn song cng chia s mi trng, tt c cc trm s pht v thu trn cng mt knh v tuyn. Vn c bn l cc trm khng th lng khi khi ang gi v v th khng th pht hin xung t. V th mt k thut c h tr cho Wi-Fi gi l chc nng iu khin phn tn (DCF). Nn tng k thut c bn l nh ngha mt h thng ca cc khong thi gian i v cc b m thi gian li gim nhng khng hy b cc xung t. Mt trm Wi-Fi s ch pht nu n cho rng knh ri. Tt c vic truyn dn c xc nhn, v th nu trm gc khng c xc nhn, n cho rng mt xung t xy ra v th li sau mt khong thi gian i ngu nhin. Tc ng ca xung t s gia tng khi lu lng tng ln hay ang trong tnh trng trm di ng khng th lng nghe cc trm khc (vn node n). Trong mng WiMAX, giao thc yu cu/ chp nhn c h tr. Truy nhp ng ln s c iu khin bi trm gc. Cc ngi dng mun truyn ng ln u tin phi gi cc yu cu trn mt knh truy nhp trn c s tranh chp. Cho php dnh ring dng knh ng ln sau c cp pht bi trm gc s dng mt h thng chp nhn. Ch c mt trm c cho php gi trong mt thi im, nh vy khng c xung t ng ln. Do cc li ch m giao thc yu cu/ chp nhn mang li nn WiMAX h tr nhiu mc QoS. K thut truy nhp ca WiMAX c th h tr 4 loi dch v c bn. Trong Wi-Fi th chun 802.11j c h tr QoS. C hai kiu hot ng c s dng ci thin cc dch v thoi: - M rng a mi trng Wi-Fi (WME) - a mi trng c lp lch Wi-Fi (WSM) WME s dng mt giao thc c gi l truy nhp iu khin phn tn nng cao (EDCA) l mt phin bn ci tin ca DCF. EDCA nh ngha 8 mc u tin truy nhp cho knh v tuyn chia s. Ging nh DCF ban u, truy nhp EDCA l mt giao thc trn c s tranh chp m s dng mt khong thi gian i v cc b m thi gain li trnh xung t. Tuy nhin, vi DCF tt c trm s dng cng mt gi tr v do c cng u tin cho vic pht trn knh truyn. Vi EDCA mi______________________________________________________________________ 68 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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u tin truy nhp khc nhau c n nh mt khong thi gain i v b m li khc nhau. Truyn dn vi u tin truy nhp cao hn c gn khong i ngn hn. Chun cng bao gm mt kiu packet-bursting cho php mt im truy nhp hay mt trm di ng d tr knh v gi 3 n 5 gi theo tun t. EDCA khng c k thut phn pht dch v tr nht qun. N ch m bo rng truyn thoi s i t hn truyn d liu. Tr nht qun chnh xc c th c cung cp vi ty chn WSM. WSM hot ng gn ging chc nng iu khin im (PCF). Trong WSM, im truy nhp theo nh k qung b mt bn tin iu khin bt buc tt c trm phi x l knh khi bn v khng c gng truyn. Trong chu k , im truy nhp kim sot vng mi trm c nh ngha dch v cm bin vi thi gian. s dng WSM, thit b u tin phi gi mt profile lu lng miu t cc yu cu bng thng, tr v jitter. Nu im truy nhp khng c ti nguyn p ng profile lu lng, n gi li mt tn hiu bn. Nguyn nhn m WSM l mt c im ty chn l tt c cc im truy nhp c th gi li mt thng bo dch v cha sn sng ti cc yu cu profile ca trm gc V bo mt, Trong Wi-Fi, mt m ha l ty chn, v c ba cng ngh khc nhau c nh ngha: Wired Equivalent Privacy (WEP): mt m ha 104 bit hoc 40 bit trn c s RC4 vi kha tnh Wi-Fi Protected Access(WPA): Mt chun mi s dng kha WEP 104 hoc 40 bit nhng thay i kha trn mi gi cn tr nhng k trm kha. Giao thc chuyn kha c gi l giao thc ton vn kha theo thi gian TKIP(Temporal Key Tntegrity Protocol). IEEE 802.11i/WPA2: Chun ny da trn cng ngh mt m ha mnh uc gi l chun mt m nng cao AES. Mt m trong WiMAX ban u l chun mt m s (3DES). Sau kt hp vi chun mt m nng cao AES v m bo tnh bo mt cao.

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V tnh di ng trong WiMAX v Wi-Fi cng c nhng khc bit. Trong khi chun 802.16 ca WiMAX c thit k cho truy nhp bng rng di ng m bo tc cao v chuyn giao khng gin on, m bo tc di chuyn ca phng tin giao thng. Vi Wi-Fi tnh di ng b hn ch v ch m bo cho vic di chuyn tc thp.

Tng kt______________________________________________________________________ 69 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Sau khi tm hiu kin trc mng WiMAX vi nhng k thut u vit c s dng gip cng ngh WiMAX c nhng c im vt tri nh kh nng che ph trong c iu kin tm nhn thng (LOS) v khng theo tm nhn thng (NLOS). cho php nh khai thc cung cp d liu bng rng n nhiu i tng khch hng. Cng ngh WiMAX cng c rt nhiu u im em li t cc cng ngh nh: cng ngh OFDM, iu ch thch nghi v hiu chnh li. Ngoi ra, WiMAX cng c nhiu tnh nng tu chn nh: ARQ, knh con ho, phn tp, v m ho khng gian - thi gian ha hn s em li cho nh khai thc hiu sut v cht lng dch v cao hn so vi cc cng ngh khc. Da vo nhng c s k thut ny nh gi tnh kh thi ca cng ngh gip cc nh khai thc dch v cn bng gia gi thnh v hiu sut; la chn cc tnh nng hp l cho m hnh kinh doanh c th.

Chng 3______________________________________________________________________ 70 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Kh Nng ng Dng WiMAX Ti Vit Nam Trong chng mt v chng hai ta thy ,so vi cc h thng truy nhp bng rng, WiMAX c nhng th mnh vt tri nh h tr nhiu cu hnh , c kh nng ph sng rng khp,tnh bo mt cao nh h tr chun mt m d liu tin tinv v.. vi nhng dch v c th c cung cp trn mng WiMAX nh thoi truyn thng hoc thoi qua Internet (VoIP); truy cp Internet tc cao; hi ngh truyn hnh; mng ring o; truyn hnh di ng; gii tr trc tuyn v nhiu dch v gi tr gia tng khc. Chnh v nhng u th m WiMAX ang thu ht c s quan tm rt ln ca th gii. 3.1 Tnh hnh trin khai WiMAX trn th gii WiMAX hin ang c th nghim mt s nc nh Nht Bn, Nga v Vit Nam. Cng ngh ny c bit ph hp vi nhng khu vc c a hnh phc tp ,v nhng ni m h h thng cp ng cha c trin khai, mt khc, do bn knh ph sng rng v tn hiu mnh cho php sng WiMAX tip cn c c nhng khu vc xa xi ho lnh, iu m WiFi khng th thc hin. Ti mt s ni dch v DSL c trin khai hng lot nhng cht lng ng dy km v khong cch t ngi dng n cc tng i trung tm xa hoc mt dn c thp nn tc ng truyn khng m bo.WiMAX vi kh nng h tr cht lng QoS ,vng ph sng xa ,tc cao,ngoi ra vi u im khng y v vi chn 802.16e h tr kh nng di ng khin cho WiMAX s l mt la chn tt Hin nay cc h thng ch yu c trin khai vi cu hnh im a im v cu hnh li 3.1.1 Tnh hnh chung Cng ngh ny hin mi ch c th nghim mt s khu vc trn th gii. L cng ngh ra i sau nn WiMAX c nhiu u im khc phc c mt s kh khn m nhng cng ngh trc gp phi. Din n WiMAX thu ht c s quan tm ln ca rt nhiu nh cung cp dch v v thit b vin thng hng u nh: Tp on Intel lin tc vn ng v ng h chun WiMAX 802.16. H u t ti 600 triu USD cho Clearwire, hng cung cp dch v khng dy tc ______________________________________________________________________ 71 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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cao cho ngi tiu dng ti M.Vo thng 7/2007 Clearwire lp k hoch cho dn IPO 400 triu USD vi s u t 600 triu USD t Intel. Chin lc ca Intel trong vic to ra mt sc ht th trng vi cc chip thng qua vic u t vo mt nh cung cp dch v m s cn thit nhiu chip trong cc thit b v CPE.[16] NextNet cng ang c bit n Motorola cho nhng d n ca mnh. R rng, Motorola bn thn l mt nh cung cp mt bng WiMAX rng ln do vy Motorola thu ht nn tng c lp t ca NextNet. Tuy nhin, Motorola nhn c nhiu thin v vic c mt nn tng c lp t quy m t cc nh cung cp khc. Chng ta hy xem v tr th trng k tip ca cc nh cung cp vin thng trong th trng WiMAX. Sam sung ang dn u vic ng gi cc sn phm WiMAX di ng, Alcatel v Siemens ang to ra nhng n lc mnh m a cc sn phm WiMAX ca h ra th trng. OEMing t Airspan Qualcom cn phi duyt li WiMAX trc khi ri khi xng. Vic kim nh thc t xu hng hot ng WiMAX s l th t ca cc nh cung cp trong th gii WiMAX Cng nh Intel, cc sn phm WiMAX u tin c ch i n t: Proxim, hng ch to kinh doanh v WLAN, y c cc sn phm WiMAX ang trong cc phng th nghim. Truyn thng Ensemble. Mt s tp on truyn thng v dch v Internet ln trn th gii nh News Corportion hay Yahoo cng mt n WiMAX v coi y l cng ngh b sung chomng di ng v bng rng c nh. Ti Nht, lin minh SoftBank - Motorola hin cng cho trin khai WiMAX di ng trn di tn 2.5 GHz bt u t thng 9/2006.Trong khi , mt t th nghim cng ngh vi quy m ln cng ang din ra ti Nga. Hai hng thit b cng ngh Avalcom v Aperto nc ny kt hp vi nhiunh cung cp dch v hin thc ha d n ti nhiu khu vc nh Moscow, Siberia...[2] Ring ti Hn Quc, do khng mun chng kin du hiu "Intel Inside" chim lnh trn th trng bng rng khng dy, Samsung tch cc ng h pht trin mt cng ngh tng t mang tn WiBro nhm gt b WiMAX ti nc ny. Cc hng vin thng y bt u kinh doanh dch v WiBro khu vc trung tm, trng i hc v cc tuyn giao thng cng cng chnh trong Seoul. Khch hng s mua th tr gi t 170 USD n 300 USD ci vo my tnh xch tay cn th h tr nhng thit b di ng khc nh PDA v in thoi thng minh s c mt trn th trng vi thng na. Flarion, hng ny c mt th nghim chy th Nam Hn Quc ca c cu bng rng khng dy s dng cng ngh anten thng minh v h tr 802.16a. Hn Quc c xem nh mt lnh th ni m bng rng khng dy c thng qua nhanh nht. Tuy nhin, ngi lnh o ca hng ny quan tm n chun 802.20 hay Mobile-Fi.______________________________________________________________________ 72 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Fujitsu Microelectronics ang pht trin mt thit b 802.16. Fujitsu s lm vic vi nhiu nh cung cp cc thit b trc u cui v ngh h tng thch vi thit b ca hng. Taiwan-based Gen-WAN Technology gii thiu thit b mng khng dy bng rng s dng 802.16a, ngh cc trm gc, cc thit b u cui c nh v di ng, cc b lp v cc h thng qun l mng. Hng ny s tung ra th trng cc sn phm c gi l BWIA, ban u cho s an ton cng cng v cc mc ch qun s, WiMAX ngh cc tn hiu ng tin cy hn mng t bo trong tnh hnh khn cp. Wi-LAN, mt trong nhng ngi sng lp ch cht v WiMAX, a ra th trng cc gii php h thng tin chun ha da trn chip v s h tr hon hon vic chun ha trong thi gian ti. Cng ngh OFDM bng rng c cp bng sng ch ,bao gm c chun 802.16a v cng ty ny c mt c s h tng v hp ng trin khai vi Fujitsu Microelectronics. Broadcom v Texas Instruments cng ang a ra nhng qung co v WiMAX v c mong ch a vo th trng bn cnh Intel v Fujitsu. y l mt lnh vc m cc hng ch to chip s nh r tp hp cc kh nng ct li v iu khin cc chc nng ct li v th h gi vai tr c bn trong xu hng pht trin ca 802.16. Cc i tc cng ngh u tin ca Intel t th trng BWA, cc hng ny s s dng cc sn phm Intel sp ti trong cc trm gc c quyn trc y ca h, l Alvarion v Aperto Networks. Alvarion c mt hp ng quan trng h tr China Unicom vi cc thit b WiMAX cho 6 thnh ph c gii thiu u tin. AirTap Communications l mt trong nhng ngi ng k u tin vo th trng mng WiMAX M, phc v cc SME v cc nh kinh doanh ln trong phm vi cc vng thnh th. 3.1.2 Cc thit b c gii thiu trn th gii 4/2005, h thng WiMAX da trn chip (SoC) ca Fujitsu c gii thiu, ni ln nh mt ngi ng u trong cng ngh bn dn khng dy bng rng. Vi mt s b sung vo lp MAC v PHY ca IEEE 802.16-2004, Fujitsu WiMAX SoC, MB87M3550 a ra mt gii php mang li li nhun cho c cc ng dng trm gc v trm thu bao. SoC c tch hp cao ny b sung iu khin v tuyn MAC, PHY v tt c cc mch tng t cn thit cho cc bng tn c cp php v khng c cp php thch hp. Mt s h thng WiMAX trn th trng______________________________________________________________________ 73 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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Hng SX H thng K thut a truy nhp iu ch

Alvarion

Cambridge broadband

Navini Ripware TDD

TDD/HFDD CSMA/CA TDMA CDMA a TDMA sng mang OFDM,BP n sng Thch ng OFDM thch SK,QPSK, mang QPSK, theo chiu ng 16QAM,64 16QAM xung BPSK,QPS QAM 64QAM 16QAM K 8QPSK 16QAM,64 BPSK,Chiu QAM ln QPSK rng 2 x 1.75 1.75 bng 2 x 3.5 3.5 3 3.5 tn 7 5 7 knh(M 14 14 Hz Thng 12 Mbps 48Mbps xung:4,2M 3.5Mbps lng bps max ln:2.2 Mbps knh 3.5MHz 14MHz 5MHz 14MHz ppiuc h Nng lng pht x ca BS Anten khu vc ca BS 64 QAM --64 QAM 25dBm 29dBm 33.5dBm 13.5dBi 60 16QAM,QP SK 27-47dBm EIRP cho mi phn t antennal 64QAM 23 dBm

BeezeAcce VectaStar ss OFDM 3500 FDD FDD

Redline Wi-LAN communicati on AN-100 Ligra 3000 FDD TDMA OFDM,BPS, QPSK 16QAM

3.5 7 12Mbps 7MHz 16QAM 22/33dBm (TB/nh) 17dBi 60 14dBi 90 13dBi 120 12dBi 180 11dBi omni 17/27 dBm (TB/nh)

16.5dBi 60

360 hoc 17dBi 60 120 14dBi 90

Nng lng --pht x CPE

25 dBm 29 dBm 33 dBm

15 dBm 31 dBm EIRP


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Antenn al CPE

18 20

dBi 16.5dBi 20 STM-1

Giao 10/100Bas din eT pha BS Giao din pha CPE

10/100Base 10/100Bas T eT G.703,E1,V 35,STM-1 Bng 8 : Thit b h thng trn th trng

Cho pht thay i 2dBi 360 6dBi 120 T1,ATM/IM A 10/100 BaseT USB 10BaseT

18dBi 15 24dBi 8

18dBi 20 21dBi 12 23dBi 9.6

T1/E1 10/100Base 10/100Basse T T T1/E1 10/100Base T 10/100Base T

Fujitsu WiMAX SoC, MB87M3400 l mt b x l di tn c s tn hiu hn hp gia hai lp MAC v PHY c tch hp hon ton mang li li nhun cho cc ng dng truy nhp khng dy bng rng. SoC ny c thit k h tr di tn t 2GHz n 11GHz trong c hai bng tn cp php v khng cp php. B x l h tr tt c cc bng tn c sn t 1.75MHz n 20MHz. WiMAX SoC ca Fujitsu hon ton tun theo chun IEEE 802.16-2004 ca WiMAX v c th c cu hnh c s dng trong c hai ng dng trm thu bao v trm gc. SoC ny h tr cc lc iu ch thch ng hiu sut cao bao gm 64QAM, 16QAM, QPSK v BPSK. Khi p dng iu ch 64QAM vo mt knh 20MHz v s dng tt c 192 sng mang con, tc d liu ca SoC c th ln ti 75Mbps. Knh con ha ng ln cng c h tr nh c nh ngha trong chun. Vic nng cao hiu nng c th c thc hin vi hai ng c RISC c gn vo SoC. Hai b x ny l khng ch hp dn v vic s dng cc chc nng c bn c yu cu bi c tnh k thut WiMAX nhng cng cho php khong trng thm vo s dng phn mm ng dng ca ngi dng. MiTAC Technology, ng u th gii v my tnh c nhn, mng v cc sn phm truyn thng, gii thiu mt trm gc trong nh da trn Fujitsu MB87M3400. Trm thu bao trong nh ny hon ton tun theo cc chun IEEE 802.16-2004 v ETSI HiperMAN, h tr nh tuyn mng, truy nhp khng dy bng rng trn c s WiMAX v VoIP. c kt ni vi mt trm gc WiMAX s dng lin kt v tuyn 3.5GHz pht thoi tc cao, d liu v a phng tin, Trm thu bao kt hp vi mt anten di vi ty chn ca mt anten bn ngoi, cung cp linh hot cao nht. Aperto Networks, mt nh cung cp h thng WiMAX hng u phc v hn 200 nh khai thc 65 quc gia,. Thit b WiMAX ca cng ty s c a ra th trng l dng sn phm PM500, phn cn lica h PacketMAX. Cc sn phm______________________________________________________________________ 75 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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ny trong mt series, c trng ca chng l s ci tin hin i nht v chip, v tuyn v cc cng ngh anten s l phng tin truy nhp khng dy bng rng ca nhiu loi dch v nh video, thoi, d liu gm c VoIP. Thit b silicon WIMAX th h tip theo ca tp on Intel, tn m l Rosedale2, c la chn bi 10 nh cung cp thit b WiMAX hng u th gii nhm a ra nhng gii php th h mi cho cc mng WiMAX. Rosedale 2 l mt thit b h thng trn mt chip c chi ph thp v h tr cc chun IEEE 802.162004 v IEEE 802.16e-2005, cho php to ra cc modem WiMAX s dng cho c mng di ng ln c nh. Rosedale2 s tn dng li th ca cc mng WIMAX di ng ang c trin khai rng ri trn th gii bi cc nh cung cp c s h tng nh Alcatel. Nm trong chng trnh cng tc m rng nhm y nhanh tc trin khai cc mng WiMAX di ng, Rosedale2 l mt phn ca Chng trnh kim tra tng thch (Interoperability Testing) ton cu ca Alcatel. Cc thit b s dng Rosedale2 do vy c k vng l s tng thch khng gii hn vi gii php Universal WiMAX (802.16e-2005) ca Alcatel vn h tr v cn bn cc m hnh s dng di ng, bn di ng v c nh. Ngoi ra, tt c cc khch hng hin ti ca gii php c nh m Intel a ra trc y, modem khng dy Intel PRO/ Wireless 5116 (tn m l Rosedale), gm Airspan Networks, Alvarion, Aperto Networks, Axcelera Broadband Wireless, Proxim Wireless, Redline Communications, Siemens Home and Office Communication Devices v SR Telecom u c k hoch a ra cc gii php WiMAX s dng Rosedale2. Do tng thch hon ton v chn cm vi modem khng dy Intel PRO/Wireless 5116, Rosedale2 s mang li mt kh nng nng cp d dng cho cc khch hng. Intel cam kt hp tc vi cc khch hng ca mnh nhm a ra cc gii php truy cp Internet khng dy tc cao d dng hn v hiu qu hn v chi ph thng qua vic s dng mng WiMAX. Vi kh nng h tr hai ch mng ca Rosedale2, Intel hy vng s gip y nhanh tc trin khai cc mng WiMAX. Rosedale2 c kh nng h tr mng di ng v c thit k nhm cho php cc nh sn xut thit b pht trin cc sn phm modem ca mnh t cc ng dng c nh sang cc ng dng di ng ch vi mt thao tc nng cp phn mm n gin. Vi cc thit b s dng Rosedale2, cc nh cung cp dch v c th la chn ngay lp tc vic trin khai mt mng WiMAX di ng hay trin khai mt mng WiMAX c nh cho thi im hin ti ri sau c th d dng v hiu qu nng cp ln mng di ng. Rosedale2 l mt s b sung mi cho h sn phm rt c ch i ca Intel v cc gii php WiMAX di ng gm mt thit b PC card h tr WiMAX di ng______________________________________________________________________ 76 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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v mt thit b radio Wi-Fi/WiMAX a bng tn vi mt chip duy nht, tn m l Ofer 1/2006 T chc WiMAX Forum chnh thc chng nhn mt s thit b theo thng s IEEE 802.16-2004 (chun cho php trin khai cc mng Internet khng dy din rng) trong t mt.Nhng thit b ny bao gm phn cng ca Aperto Networks (M), Redline Communications (Canada) v Sequans Communications (Php). Tt c cc sn phm ny hot ng trn bng tn 3,5 GHz ti rt nhiu nc trn th gii, nhng khng c s dng ti M. Cc nh sn xut thit b s c kh nng bt u bng cch ngh mt s kt hp ca thit b tt nht i vi nhiu nh khai thc v thit b vng dn c ngoi tri m c th c to khung bn pha nh hay mt cn h. Vi s pht trin ca 802.16e, cc dch v WiMAX cui cng c th c sn sang cho cc thit b mang xch/ c cng nh my tnh xch tay, in thoi thng minh v cc PDA cng nh cc h thng hng hi, t v cc thit b phi truyn thng khc m c th to ra vic s dng mt kt ni Internet di ng. Ngy 11/10/2006 Intel cng b Chip WiMAX h tr WiMAX di ng u tin trn th gii. S c mt ca Intel WiMAX Connection 2250, mt h thng trn mt chip th h tip theo ca Intel c xem l mt bc tin cc k quan trng ca cng ngh WiMAX di ng . Intel cn pht trin c mt con chip silicon WiMAX vi tn m Baxter Peak dnh ring cho cc thit b di ng. Cui nm ngoi, hng in thoi s 1 th gii Nokia tng tuyn b s s dng Baxter Peak trong dng my tablet N-Series xut xng nm 2008 ca hng. 21/5/2007, b phn Fujitsu Microelectronics America (M) cng b mu silicon di ng u tin ca hng ny trn sn phm chip WiMAX mi vi hiu sut vt tri so vi cc sn phm i th khc. Sn phm c tn l MB86K21 802.16e, p ng y cc yu cu ca chng nhn WiMAX Forum Wave 2. Con chip WiMAX ny h tr knh bng______________________________________________________________________ 77 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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thng t 5-10MHz, c trang b mt lot cc ch module iu hp, tnh nng bo mt tch hp sn, h tr USB 2.0 v giao din Card Bus / PCI. D kin nhng sn phm chip hon thin u tin s c gii thiu ti th trng chu , v tip sau l M. Fujitsu cng s cung cp gi thit k h thng Systems Design Kit v gi cp pht nn tng tham chiu PC Card (PC Card Reference Platform Delivery Kit) khch hng c th d dng lm quen vi sn phm. 4/ 2008 Nokia gii thiu N810 s l mt trong nhng thit b di ng u tin trn th trng c thit k ring cho cng ngh mng khng dy tc cao Wi-Max. .Nokia vn trang b cho N810 cng ngh Wi-Fi tch hp. Theo d kin, cc mu PC Siu di ng da trn nn tng Menlow do nhng thng hiu nh Asus, BenQ v Lenovo sn xut s c trng by ti CES nm nay(2008), sau chnh thc xut xng trong 6 thng u nm. Th h tip theo ca ca Menlow s l Moorestown, d kin trnh lng vo nm 2009 Nu nh nm 2007 mi c mt s sn phm ri rc dnh cho WiMAX th nm 2008 c d bo s c bc tin nhy vt vi 100 sn phm (khng tnh cc thit b in t tiu dng v cc thit b c ci t sn). Hin Motorola ang trin khai WiMAX vi s hp tc vi cc lin minh vin thng hng u v cc hp ng hp tc vi cc cng ty vin thng hng u. Motorola c chn dng bi Wateen Pakistan, v Agni Bangladesh trin khai WiMAX trn ton quc. Motorola hin c mt s hp ng thng mi trin khai WiMAX trn ton th gii v hng lot cc cuc th nghim ang din tra trn khp khu vc chu Thi Bnh Dng WiMAX di ng mi l trin vng ln nht ca WiMAX. Vi cng ngh ny, ngi dng u cui c th c s dng Internet tc cao ln n 1Mbps, ti bt k ni no trong vng ph sng bn knh rng nhiu km. Thit b u cui ca dch v WiMAX di ng c th l cc card PCMCIA, USB, hoc c tch hp sn vo trong con chip my tnh (kiu nh cng ngh Centrino ca Intel).


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Cng theo d bo ca WiMAX Forum, nm 2009 s c 180 sn phm dnh cho WiMAX,nm 1010 l 290 sn phm, v nm 2011 l 430 sn phm. D kin vo qu 2 ny s c nhng sn phm cng ngh u tin c chng nhn h tr cng ngh WiMAX di ng. 3.1.3 Di ph hot ng ca WiMAX trn mt s nc hin nay

a/ Ph khng cp php Australia c mt s nh cung cp ang yu cu s dng cc cng ngh da trn chun 802.16. Ban u tp trung vo bng ph cp php 5.8GHz. Australia khng c ph khng cp php. i vi cc dch v truy nhp khng dy WAS, cc______________________________________________________________________ 79 Lun vn:Tm hiu kh nng ng dng WiMAX ti Vit Nam

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nh iu tit a ra mt s cc bng tn ph c sn di cc tha thun giy php khc nhau. Vi ph 2.4GHz v 5.8GHz, cc bng ny c to ra cho WAS theo iu khon ca giy php loi mt. iu ny cung cp mt mi trng iu tit public park. Nhng ngi dng tip nhn khng m bo s bo v khi nhiu t cc dch v khc v phi khng gy ra nhiu cho cc dch v khc. Cc thit b gim kh nng gy ra nhiu bi v thit k ca chng v cng sut b hn ch. Giy php loi mt khng c s dng cho cc c nhn ring l v khng phi tr chi ph cho giy php. Ti o bng 2.4GHz l c sn do. Tuy nhin, vo thi im ny n cha c bit n nu WiMAX thc hin giao din khng gian hay khng. Bng 5.8GHz nc ny hin ang khng c sn. Canada, cc bng 2.4GHz v 5.8GHz c th c s dng cho WiMAX. Cng nghip Canada khng c ph c ch nh cho cc cng ngh c th, nh WiMAX, nhng WiMAX c th c s dng bt k bng tn no, nhng ph hp vi nhng hn ch cng ngh Php, theo l thuyt c th s dng cc cng ngh WiMAX trong bng tn 2.4GHz (bng 6.8GHz khng c cng khai Php). Tuy nhin, c th c nhiu kh khn trong thc t do nhng hn ch v cng sut c a ra bi PIRE v chun ETSI. Nht, hin nay MIC khng cp pht ph cho WiMAX nhng hin nay c mt y ban nghin cu ang nghin cu MAN khng dy. Hn Quc khng bt buc chun ha cng ngh cho iu kin khng dy v do khng c cc quy tc ring qun l vic s dng WiMAX trong cc bng tn khng cp php. Thy in, bng tn 2.4GHz c m cho cc loi cng ngh khc nhau v mt h thng WiMAX s c cho php vi iu kin n tham gia vo ETSI EN 300 328 V1.5.1. Bng tn 5.470-5.7625GHz ni chung l c sn cho cc h thng da trn WiMAX vi iu kin chng hon thnh cc yu cu bt k. Bu in Thy in v i l Telecom quyt nh a ra bng 5.725-5.875GHZ cho vic s dng BWA, ph hp vi iu kin khng cp php. M c th hot ng trong cc bng tn khng cp php vi iu kin cc thit b p

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