TONG QUAN VE He THONG WiMAX CHIXYNG 1: TONG QUAN VE H$ THONG WiMAX 1.1. WiMAX la gi? WiMAX (Worldwide Interoperability for Microwave Access) la mot deg nghe khOng day bang rung, h8 trq khii !tang kit noi bang thing rung toc dO cao cho ci mpg co djnh lin mpg khong day di gong. Hai phien ban ctia WiMAX di duqc IEEE dua ra nhu sau: Binh 1.1 Md hinh wing WiMAX Fixed WiMAX (WiMAX co djnh): Dora tren lieu chuin IEEE 802.16-2004, duqc thiet ke thich hqp cho clang truy nhkip c6 djnh. Trong phien ban nay sir dung ky thu$t ghep kenh phan chia theo tin s6 trtrc giao OFDM (Orthogonnal Frequency Division Multiple) hoot dung trong ci m6i trubng shin thing - LOS (line-of-sight) vi kitting nhin thing - NLOS (Non-line-of-sight. Mobile WiMAX (WiMAX di dung): dua tren fieu chuin IEEE 802.16e, h8 trq cho clang di dung, cung cep khi tiling chuyen yang - handoff vi chuyen mpg - roaming. Tieu chuin nay sir dung phuong thirc da truy c$p ghip kenh chia tin so tnrc giao OFDMA (Orthogonnal Frequency Division Multiple Access) - li su ph6i hqp cc5a ky thuot ghep kenh va lcy thuit phan chia tin s6 c6 tinh chit Ulm giao, nit pht hqp voi m8i trutng truyen dAn da dubng nhim tang thong luqng ding nhu dung luong tang dO linh hoot trong vies quin ly tii nguyen, liin dung tai da ph6 tin, chi thin khh Ming phh song yeti citc loci dja hinh da dung. WiMAX da ducc phat trien vi ;chic phuc duct nhitng nhuqc diem cult citc c8ng nghe truy c$p bang rang tru6c day, cu the: Phan Tien Tking MSV: A13162 Trang 2 TONG QUAN VE Ht THONG WiMAX — Ciu true mem deo: WiMAX h6 trq clic ciu trim he thong bao g6m diem da diem, c8ng nghe lir& (mesh) vi phu sting khip mqi not Dieu lchien truy nh$p m8i twang - MAC, phut:mg tien truyen din h6 trq diem - da diem va dich vu rang khip b6i  mOt khe thin gian cho m6i tram di dang (MS). Neu c6 duy nhit mOt MS trong ming, tram g6c (BS) sE lien lac v6i MS tren ca set diem - diem. Mat BS trong mOt ciu hinh diem - diem c6 the sir ding anten chum hgp han a bao phu clic khoing each xa han. — Chit lueing djch vu QoS: WiMAX c6 the dirge t6i in dOng d6i yen h6n hqp luu luqng sE duct mang. CO 4 loci djch vu dirge h6 trq: djch vu tip phut to nguyen (UGS), djch vu hei Wong thbi gian thvc (rtPS), djch vu hal yang khOng thin gian thirc (nrtPS), n6 km tot nhit (BE). — Tries kluti nhanh, chi phi thip: So sloth von trien khai care giii phap co day, WiMAX yeu eau it ho#c kh8ng eh bit rent sir xay dying thiet lop ben ngoli. VI du, duo h6 de Mo ranh cat dubng cap thi kh8ng yeu c$u. Ngotli ra, doa ten clic chuin m6 cha WiMAX, se kh8ng c6 so dOc guy& ye lieu chain nay, din den viec chnh trash chit nhilu nha sin xuit, lam cho chi phi diu to mOt he thong gut= ding ke. — Djch vu da mat: Cach thirc not ma QoS dirge pha ► phtit n6i chung doa vac so thea thu$n mire djch vu (SLA - Service Level Agreement) gitta nha cung cap dich vu va ngubi sir ding cu6i can. Chi flit han, mOt nha cung alp djch vu c6 the cung cap clic SLA khac nhau tai care thug bao ldiac nhau, thklm chi till nlittng ngubi dhng !chat nhau sir ding sung MS. Cung cep truy nh$p bang rung co dinh tong Meng khu voe d8 thi va ngotti 8, not chit luqng cap deg thl kbm ho#c dim vao 16.6 khan, khlc phuc thiet bj s6 tong nhttng yang met da thip not ml cat nhan t6 c8ng nghe vh kinh ti thyt hien phut trier bang rang rut thich thirc. — Tinh Wang thich: WiMAX duct )(Ay (long de tors thinh mOt chuin quOc te, Mo ra so a ding d6i vdi ngubi dOng cu6i sung a truyen tai vi sir dyng MS chit hq 6 clic vi tri khitc nhau, hetet yeti cat nhti cung cap dich vu khac nhau. Tinh tucmg thich bito ve so ditu to cua mOt nha van hash ban diu vi n6 c6 the chqn lira thiet bi ttr care nhi  thiet — Di ding: IEEE 802.16e b6 sung them tic dec diem chinh h6 trq khi !rang di dung. Nhttng cii den lap vat ly OFDM (ghep kenh phin chia tin so titre giao) va OFDMA (da truy nh$p pit chia tin s6 trot giao) de h6 trq cat thiet bi va the dich sit tong mOt m8i tnrbng di dung. Nhttng cii lien nay, bao g6m Phan Tien Tang MSV: A13162 Trang 3 TONG QUAN VE Ile THONG WiMAX OFDMA mit rung duqc, MEMO (Multi In Multi Out - nhieu diu vac nhieu diu ra), vi h8 thy del vat the dO idle/sleep vit handoff, se cho phep kha Wing di dung (fly du 6 the dO tea 160 km/h. Mang WiMAX di dung cho phep ngtriti sfr dung c6 the truy cop Internet khang day bang thong rung Ali bit cu dfu c6 phi sting WiMAX. — Hog dung NLOS: Khii tiling hog dung curt mang WiMAX ma Idling did hei tern nun thing gitta BS vi MS. KM Wing My cos n6 gift') ac sin phim WiMAX phAn phit dii thong rung trong met mei truing NLOS. — Phu sting rung han: WiMAX h8 trq dung nhieu mire dieu chi, bao gem BPSK, QPSK, 16QAM, 64QAM. Khi yeu au yeti bO khuich dg tong suit cao vi hog dung vol di& the mire thip (vi du BPSK ho(ic QPSK). Cac he thong WiMAX c6 the phi sang mOt yang dirt 13± rung !chi dutrng truyin gifts BS vi MS kiting bj an frit Met rung pham vi bj giOi hp hien tai mitt WLAN ding cung (hotspot) den phi= vi rung (hotzone). O nhttng dieu kien tot nil& ce the dot (bye phgn vi phi sting 50 km v6i toe dO dit lieu bj ha thip (mOt vii Mbit/s), pham vi phi sting dien hinhli gin 5 km v6i CPE (NLOS) trong nhi vit gin 15km vii mOt CPE duet not vii mOt anten ben ngoii (LOS). — Dung lucmg cao: C6 the dot duce dung luqng 75 Mbit/s cho cac tram g6c yeti mOt kenh 20 MHz trong cac dieu kien truyin song tot nhit. — Tinh mei rung: Chuin 802.16 -2004 M trq cac dii th8ng kenh dui s6 v8 tuyen (RF) mem deo vi sfr dung loi the kenh tin s6 nay nhu la mOt each di tang dung luqng martg. Chuin cftng djnh r8 h8 trq deli vai TPC (dieu khien c8ng suit phit) vh cic phep do chit luqng kenh nhu the Gang cu them vtio de h8 trq sa dung ph6 hieu quit. Chuin dA dupe thiet Ice de 4t tt le len tai hang tram th#m chi hang nghin nguOi sa dung trong mOt kenh RF. H8 trq nhieu kenh cho Step cac nhb the to thiet bj cung cap mOt phuang tien de chi trcmg vho phi= vi su dung ph6 vi nlang quy djnh cip phit duce mai r8 bid cac nhi v#n hinh trong the thj truing quac to thay deli !chic nhau. — Bin mkft: Bing each ma hOa the lien kit v8 tuyin gifta BS vi MS, su dung chuin ma hba tien tien AES, dim bao sv tan von ctia Ott lieu trao deli qua giao dien v6 tuyen. Cung cip cho ac nha v#n Minh vii sv bito ve manh cheng lai nhftng hAnh vi dinh cip djch vu. Phan Tien Ting MSV: A13162 Trang 4 TONG QUAN VE H$ THONG WiMAX 1.2. Cic chuAn chit WiMAX 1.2.1. Chan IEEE 802.16-2001. ChuAn IEEE 802.16-2001 duqc hoar) think vho thing 10/2001 vh duqc cemg 136 vho 4/2002, djnh nghia dac ti k9 thu$t giao din kitting gian WirelessMANni cho Mc ming vbng d8 thj. Dac diem chinh Ma IEEE 802.16-2001: + Giao dies !thong gian cho he thing truy nh$p khong day bang rung do djnh host dung 6 did tin 10 - 66 GHz, cAn th6a man tim thin thing. + Lip vat 15 , PHY: WirelessMAN-SC. + T6c dO bit: 32 -134 Mbps yeti kenh 28 MHz. + Dieu chi QPSK, 16 QAM vi 64 QAM. + Cic dii thong kenh 20 MHz, 25 MHz, 28 MHz. + Ban icinh cell: 2 - 5 Ian. + Ket n6i c6 djnh hueng, MAC TDWIDMA, QoS, bin mot. 1.2.2. Chan IEEE 802.16a. Vi nhong kith khan trong then khai chuin IEEE 802.16, hueng vho vies sir dung tin s6 tir 10 - 66 GHz, mOt dv in sou d6i c6 ten IEEE 802.16a da duqc holn thhnh vho thing 11/2002 vh duqc c6ng b6 via thing 4/2003. Chuim nay duqc me rung h6 trq giao dien kh8ng gian cho nhemg ten s6 trong bang tin 2-11 GHz, bao g6m ci nhttng phi cup phap vh khong cep phip vi khemg cin that man dieu ;den tim nhin thing. Dac diem chinh curt IEEE 802.16a nhu sau: + B6 sung 802.16, cic hieu chinh MAC vi cic dac diem PHY them vho cho 2-11 GHz (NLOS). + Tic dO bit: teri 75Mbps yeti kenh 20 MHz. + Dieu chi OFDMA vOl 2048 sting mang, OFDM 256 sting mang, QPSK, 16 QAM, 64 QAM. + Dii thong kenh c6 the thay d6i gilts 1,25MHz vi 20MHz. + Ban lcinh cell: 6 - 9 lcm. + Lop vat PHY: WirelessMAN-OFDM, OFDMA, SCa. + Cic chile niing MAC them vtio: h6 trq PHY OFDM vi OFDMA, h8 trq cemg nghe Mesh, ARQ. Phan Tien Tang MSV: A13162 Trang 5 TONG QUAN VE lit THONG WiMAX 1.2.3. Chula,: IEEE 802.16-2004. Tilling 7/2004, chuim IEEE 802.16 - 2004 hay IEEE 802.16d dupe chip nh$n thOng qua, ket hap cuts cac chuk IEEE 802.16 - 2001, IEEE 802.16a, ling dung LOS 6 did tan s6 10- 66 GHz vi NLOS ti did 2- 11 GHz. Khii Ming v8 tuyen b6 sung nhu lh "beam forming" vi kenh con OFDM. 1.2.4. Chuin IEEE 802.16e. Chan khong day bang thong rung 802.16e vai ten gqi Mobile WiMax cho phep tram g6c ket n6i tai nhitng thiet bj dang di chuyin. Chum nay gap cho the thiet bj a cac nhe sin xuit ray cti the lam viec, tutmg thich t6t voi cac thiet bj tfc ciic nha san xuit khac. 802.16e hqat dung 6 cac bang tin nhe han 6 GHz, t6c dg len teri 15 Mbps yen kenh 5 MHz, ban lcinh cell to 2 - 5 km. WiMAX 802.16e c6 h6 trq handoff vi roaming. Su dung SOFDMA, mOt c8ng nghe dieu the da song mang. Cac nhi cung cep dich vy tan khai 802.16e cling c6 the su dung Truing d6 cung cup dich vp c6 djnh. 802.16e h6 trq cho SOFDMA cho phip s6 song mang thay d6i, ngoii the m8 hinh OFDM vi OFDMA. Sr phAn chia sting mang trong m8 hinh OFDMA dirge thiet ke d6 t6i thieu inh Wing cua nhigu phis thiet bj ngutti dOng yeti anten da hueng. Cu the han, 802.16e dim ra h6 trq cii den h6 trq MIMO vi AAS, cling nhu cit handoff cimg vi mem. NO cling cii tien cac khi nAng tilt kiem c8ng suit cho cfic thiet bj di dung vi cic dac diem bao mot linh hoot han. Phan Tien Tang MSV: A13162 Trang 6 TONG QUAN 'VE HE THONG WiMAX DM tin s6 10-66GHz <11GHz <6GHz M6i truang truyen Line of Sight (LOS) Non Line of Sight (NLOS) NLOS T6c dO 32-144Mbps Up to 70 Mbps 10M - 30M Dieu the Dieu the dun sOng Mang QPSK OFDM 256 sOng mang con QPSK, 16 QAM, 64QAM S-OFDMA QPSK, 16 QAM, 64 QAM Mirc di ding C6 dinh c6 dinh CO the cho the dO di chuyen thip Bang th6ng kenh 20,25,28MHz 5- trtn 20MHz 1.25-20 MHz Bin Icinh cell 1.7-5km 5 tai 10Ian; toi da 50 km thy thuOc vao dieu kien truyen 1.7-5km Bang 1.1 So seinh cac chain IEEE 802.16 Voi nhftng dtic diem va su phat den cult cac chuin IEEE802.16 n6i tree, to co the 'than thiy dtrqc sulchic nhau ca ban cang nhu firth ke thira caa cic chuin nay. IEEE yin dang nghien cuv va dui ra cac chuin 802.16 mai nhim hoen thien chuin nay. Vi du nhu: IEEE 802.16f-2005, IF.F.E802.16g-2007 b6 sung cho thu tyc quitn lfr ke hooch vtl djch Ai, IEEE 802.16k-2007; IFFY. 802.16-2009 cling c6 tieu chart IEEE 802,16-2.004, 802.16e-2005 vi 802.16-2004/Cor1-2005, 802.16f-2005, vi 802.16g-2007, 802.16m 1.3. Phi WiMAX. WiMAX - thiet bi mem deo se dtrqc phep hoot ding tong ca hai dai duct ding Icfr va kh8ng ducm ding Icfr. 1.3.1. Bang tin piing kj Cfic giai phap clang k9 cung cep cac tru diem chit lucmg djch vu duct chi thien cao han cac giai phitp !thong clang k9, chip nh$n NLOS tot han a cac tin s6 thip, ne co mOt nein quy deg suit dutmg xu6ng ring han va co the h6 trq cac anten trong nhtl t6t han. Giai phip (tang kfr cho phep kiem so& qua cach sir dung ph6 vil Watt. Phan Tien Tang MSV: A13162 Trang 7 TONG QUAN VE He THONG WiMAX a Bins tin 1111nz $ 2.5 GHz DA dirge dip ph& trong phin 16u the gi6i, bao gem bile M9, my Latin, D8ng vu Tay Au va nhieu ming caa chau A - Thai Binh Duang nhu mOt bang tin dang 1c9. MOi qu6c gia thubng cep phit dal khic nhau, vi v$y ph6 dupe cup phit qua cac vang c6 the tfr 2,495 GHz den 2,690 GHz. Tong ph6 kha dung 18 195 MHz, bao gtom cac did pheng ye Nal cac kenh MDS, gba 2.495 GHz va 2.690 GHz. HO trq FDD, TDD. Ph6 tren tnoi dling k9 la 22.5 MHz, mOt block 16.5 MHz vtl mOt block 6 MHz, tong s6 8 clang 1E9. b. Bins tin an Id 3.5 GHz. Chau Au, vien chuin vier th8ng Chau Au dA plan ph6i dal 3,5 GHz, bit diu dirge sir dung cho WPLL, cho cac gi8i phap WiMAX clang ky. T6ng ph6 khi dung thay 461 then qu6c gia nhung ned chung khoing 200MHz gifts 3,4 GHz vi 3,8 GHz. HO trq FDD, TDD. MOt vii qu6c gia chi sfr dung FDD trong khi cac qu6c gia khic cho s* dung FDD hokIc TDD. Ph6 ben m61 slang Icy thay d6i ta. 2x5MHz den 2x56 MHz. 1.3.2. Bing tin khOng ding 45 56Hz Phan 16n cac qu6c gia tom the gi6i dA stl dung ph6 5 GHz cho Mc bang ding kheng long k9 nhu: Wing 5,15 GHz va 5,85 GHz Cac giiti phap kitting dling 1c9 cung cep mOt vii thu$n lqi chinh ham cac gi8i phap Clang k9, bao Om chi phi ban dL thip han, rut m nhanh han, vi mOt bang chung c6 the dirge su dung 6 phin 16n the gi6i. Cac ici kb My dang thu but sir quan tam v8 c6 khi Ming cho sir chip nhen bang rung nhanh ch6ng. Tuy nhien mOt giai phap kh8ng clang 1c9 thi khi nAng nhiL cao han, va nhieu sv canh tranh desi tied Mc nha kinh doanh bit dung sin cho viec trim khai. MOt gi8i phip kitting clang k9 se khang duqc xem nhu mOt sv thay the cho giai phip dang ky. MOi giai phip cung cep mOt thi twang khic nhau dva vio str thoa hiep gifts chi phi vi QoS. 1.3.3. Cdc being tin thtyc ii xuit cho WIMAX win thi gtdrt Cac bang tan dirge Diln dart WiMax trong xem xdt va v$n dung ca quan quip 19 tan so cac nu6c phan b6 cho WiMax la: — Bang tin 2,3-2,4GHz (2,3GHz Band): dirge de St sti . dung cho Mobile WiMAX. Tai Han Qu6c bang My dit dirge trien khai cho WBA (WiBro). — Bang tin 2,4-2,4835GHz: duqc de xuit sfr dung cho WiMAX trong Wang lai. — Bang tin 2,5-2,69GHz (2,5GHz Band): duct de St sir dung cho WiMAX di dOng trong giai don diu. — Bang tin 3,3-3,4GHz (3,3GHz Band): dirge de xuit s6r Mpg cho WiMAX c6 djnh. Phan Tien Tang MSV: A13162 Trang 8 TONG QUAN VE He THONG WiMAX — Bang ten 3,4-3,6GHz (3,5GHz Band): &roc de xuit sfr dung cho WiMAX c6 djnh trong giai door du: FWA (Fixed Wireless Access)/WBA (WideBand Access). — Bang ten 3,6-3,8GHz: dirge de 'cult so. dung cho WiMAX c6 djnh (WBA) vil cap cho Chau Au. Tuy nhien, bang 3,7-3,8 GHz dit dirge dung cho ve tinh vigil tilting Chau A, nen bang ten My khong dirge st• dung cho Wimax Chau A. — Bang tin 5,725-5,850GHz: dirge di xuat s* dung cho WiMAX c6 djnh trong giai clop du. — Ngoli ra, mOt s6 bang tin Ichic phitn b6 cho BWA cOng dirge mOt so nuoc xem xat cho BWA/WiMax la: bang tin 700-800MHz (< 1GHz), bang 4,9-5,1GHz. 1.3.4. Cdc bang hiss it Viet Nam cd khd niing dank cho WiMAX — Bang tin 2,3-2,4GHz: C6 the danh (loon bang tin My cho WiMAX. Bang tin 2,3-2,4GHz thich hop cho ca WiMAX c6 djnh va di (tong. — Bang tan 2,5-2,69011z: Bang tin My hien nay dang dirge s* dung nhieu cho vi ba vi MMDS Nip thing chti yeu 6 Hi nOi wit thinh ph6 H6 Chi Minh) Ngotti ra, bang tan nay II mOt trong cac bang tan duce de )(at su dung cho 3a Bang tin nay loi li bang tan dirge dank gia la thich hop nit& cho WiMAX di ding va da duce Dign din WiMAX )(sic nhen chinh thtic 11 bang tin WiMAX. MOt s6 nuke cOng d1 danh bang tin nay cho WiMAX nhu My, Mehice, Brazil, Canada, Singapo. VI v$y, de nghj danh bang tin 2,5-2,69GHz cho WiMAX. — Bang tan 3,3-3,4GHz: Theo Qui hooch ph6 tin s6 VTD qu6c gia, bang tin nay duce Olin b6 cho the nghiep At Ves tuyen djnh vi, c6 djnh ve ltru ding. Ve phis clan sir va quilt' su veil chua co he thong Mc, duqc trien khai tong bang tin my. Do do, c6 the cho phep s* dung WiMAX trong bang ten 3,3 - 3,4GHz. — BAng tin 3,4-3,6GHz, 3,6-3,8GHz: D6i v6i Viet Nam, he thong 4 tinh VINASAT su dung mOt s6 doon bang tan trong bang C va Ku, trong d6 cal bang ten 3,4-3,7 GHz. Ngohi ra, (loon bang tan 3,7-3,8 GHz m#c de chua su dung cho VINASAT nhung c6 the dupe s* dung cho cac from mit dat lien loc v6i the he thong ve tinh !chic. VI v$y kheong nen tan khai WiMAX trong bang tin 3,4-3,8 GHz. — Bang tan 5,725-5,850GHz: Hien nay, bang tin My da dupe BO qui djnh dart cho WiFi. Neu cho phdp tan khai WiMAX trong bang tan My thi cOng se hp 64 bang tin dinh cho WiFi. Bang tin nay c6 the thich hop cho the he Phan Tien 'fling MSV: A13162 Trang 9 TONG QUAN VE He THONG WiMAX thong WiMAX b vang n8ng th8n, vbng Mu, vang xa, b d6 c6 the cho phep he thong WiMAX phat veti deg suit cao han de giarn gig thanh then Mug he thong WiMAX. VI voy, de nghj cho phep trier khai WiMAX trong bang tin 5,725-5,850GHz nhung WiMAX phiti clang chung bang tin vi phai bao ve cic he th6ng WiFi. Nhu vtly, vbi hien tang sil dvng bang tin tai Viet Nam nhu tren, cac bang tin c6 Icha Wing dinh cho WiMAX et Viet Nam la: — Bang tin 2,3-2,4GHz vi 3,3-3,4GHz cho cic he thong truy c(ip kh8ng day bang rung, kg ea WiMAX. — Bang tin 5,725-5,850GHz cho cast he thOng truy cop kh8ng day bang rung, ke ca WiMAX nhung cic he th6ng nay phii clang chung bang tin yeti cic h>i thong WiFi vOi dieu kien bao ve ctic he thong WiFi hog dOng trong bang tin nay. — Bang tin 2,5-2,690GHz cho cic he thong truy cop !thong day bang rung, kg ca IMT-2000 va WiMAX. Chlnh phi da cep phep thu nghiem djch vp WiMAX di dOng tai bang tin 2,3-2,4 GHz vii bang tin 2,5-2,69 GHz. (Theo deg van s6 55351VPCP-CN dm Van phemg Chinh phi). 1.4. Truyin song. Trong khi !lieu ding nghe hien dang tan tai cho !thong day bang rung chi c6 the cung cep phi sang LOS, Gang nghe WiMAX ducrc toSi uu de cung cep phi sang NLOS. CEng nghe den den ctia WiMAX cung cap tat nhit cho ca hai. Ca LOS vi NLOS bj anh huong bei cic d#c tfnh dirbng truyen m8i tru&ng cis chimg, ten thit dutmg don, vi ngan guy' kit nhi v8 tuyen. Trong lien lac LOS, mOt tin hieu di qua mOt dirtmg Ulm tiep vi Ichong N tic nghen tir may phit din may thu. MOt lien lac LOS yeu cau phin Ion mien Fresnel this nhAt thi kh8ng bj nein cim cis bit Id vet can nao, neu lieu chain nay ;thong thda man thi c6 sir thu nh6 ding ke cubng dO tin hien quan sit. DO her Fresnel duct yeu ciu phu thuOc vao tin s6 hoM Ong vi Ichoing each gifts vi tri miy phit vi may thu. Trong lien lac NLOS, tin hieu den miy thu qua phin xa, tin xa, nhigu xa. Cic tin hieu den may thu bao gam cac thanh phin hY dubng tnrc dip, cic dutmg duqc phim xp nhieu lin, Wing luqng bj tin xa vi cic thrtmg truyen bj nhigu xa. Cic tin hieu nay c6 Idioang trg khic nhau, suy hao, phan cvc vii dO on djnh quan hu vbi dubng truyen trim dip la nguyen nhan gay ra nhigu ISI vi mio tin hieu. Dieu d6 !thong phai la van de deli ved LOS, nhung yeti NLOS thi Iai la van de chinh. Phan Tian Tang MSV: A13162 Trang 10 TONG QUAN VE HE THONG WiMAX C6 nhieu tru diem ma nhttng trier khai NLOS too ra ding khao !chit. VI du, S yeu cau 1#p ke hooch chat the va giai Igut chiIu cao anten ma t h rong lcheong cho phdp anten duqc be trf cho LOS. Vai nhOng Wen khai ti bao ke nhau phom vi rung, nai tin s6 duce saf dtmg loi la tai hp, ha thip anten la thufm lqi de giim nhieu kenh chung girra tic vj trf cell lien ke. Dieu nay thuang c6 tic dung fink day cic torn etc hoot dung trong cic dieu lden NLOS. Cie he thong LOS khong the giam chi& cao anten bai vi lam nhu vay se c6 tic dOng den throng quan sit Ulm tikp duqc yeu au tfr CPE den tram geoc. Hinh 1.2 Minh hpa heat dong WiMAX. CEng nghe NLOS cfing giam phi ton cli at bang cich d#t dm% cic mai the that bi CPE dimg nhu nguyen bin vl giant bat kh6 khan dinh vj tri cic dia diem at CPE thich hqp. CEng nghe cang giam bat nhu ciu quan sit vj tri thiet bj phis truck vl cli thien dt) chlnh xic ca a cic c8ng cu lop kg hooch NLOS. CEng nghe NLOS vl nhttng firth ning dupe Hang cao trong WiMAX to kha nal% a* dung Net bj phis dau khich hang (CPE) trong nhl. 1.4.1. Dien chi thich nghi. Dieu chi thich nghi cho phop he th6ng WiMAX dieu chinh so de diet' the tin hieu phu thuOc Arlo diau kien SNR cart lien kit v8 tuyen. Khi lien ket vo thy& chit luqng cao, so de diets chi cao nhit duqc sfr dung, dua ra he thong dung luvng lan hon. BPSK SNR = 6dB, lbit/Hz QPSK SNR = 9dB, 2bit/Hz 16QAM SNR = 16 dB, 4 bit/Hz 64QAM SNR = 22dB, 6 bit/Hz Binh 1.3 B6n kinh cell quan hg vol dau chi thich nghi. Phan Tien Tang MSV: A13162 Trang 11 [...]... thbnh te 48 sting mang con de lieu, 8 sting mang con hoa lieu Cac song mang con de lieu trong mai !them duce holm vj di to m cac kenh con trong nhom VI wcsty, chi cac vi tri hoa fieu trong cum duqc bieu diin Phan Tien Tang MSV: A13162 Trang 29 CAC KI THUAT SIT DUNG TRONG WiMAX trong hinh 2.15 Cie s6ng mang con d& lieu trong cum dirge phin b6 cho nhieu kenh con Tuong tv vei ctiu true cum DL, mOt ciu frac... lai trong qua trinh truyen din ,11111111116L ne chunk 4 User A • Uwe frequency • Um C 1111 User D Hinh 2.13 Sr sap xip theo hai chau trong OFDMA 2.2.2 Malin qc 111th vuvt Uu diem ctia viec det sin lich trinh nay la viec truyen din van hoot ttOng met each On djnh trong tnrtmg hqp qua tai vi s6 luqng thug bao ding IcSr vuqt qua cho phdp lam Phan Tien Tang MSV: A13162 Trang 26 CAC KT THUAT SIT DUNG TRONG. .. Whim 6 bit mOt nhim lieu li QAM64) Phan Tien Tang MSV: A13162 Trang 20 CAC KY THUAT SIT DUNG TRONG WiMAX OFDM hi mOt ding nghe chia TIM bang tan thlnh de bang nhe hon .Trong WIMAX then chuan 802.16d, dit ap dung ding nghe ntly VI v(ty WIMAX fixed c6 the host dOng duqc trong m8i twang NLOS (Non Light of Sight) Trong WIMAX fixed dirge chia dui& 256 sang mang con, 19811 danh cho de lieu, con lai dinh cho... 24 song mang con hoa lieu trong 3 Iccr hieu OFDM Hoin vj lien ke nh6m mOt kh6i cic s6ng mang con lien ke de hlnh thinh mOt kenh con hoin vi lien ke bao g6m DL AMC, UL AMC vi c6 clu true tircmg to MOt bin g6m 9 s6ng mang con lien kb trong mOt kjr hieu, vOi 8 gin cho dtt lieu vi 1 grin cho hoa tieu MOt khe trong AMC doge djnh nghia Mir mOt top hqp cic bin cria kieu (NxM=6), trong de N 11 s6 bin lien... tap thong tin trong thii kenh — UL ACK: UL ACK duqc cep phit cho MS de h6i titp chip nhen DL HARQ 2.2.6 Tong quilt vi Mang (Frame) Hlnh ye dual day glen thieu mOt cich khIi quit ye khung OFDMA Phan Tien T#ng MSV: A13162 Trong 31 cAc m THuAT sir DUNG TRONG WiMAX OFDMA symbol amber k A-•) k+S 2 t.? tin 11•1111,114815 M DURSO DI Watt DI Mass nab Hinh 2.18 Cdu Ink khung OFDMA 2.2.7 Coe phin trong kissing... dinh, de khi trong preamble khang c6 th8ng tin thi ne se m8 to dja chi Phan Tien Tang MSV: A13162 Trang 32 CAC K! THUAT St DUNG TRONG WiMAX a DL-MAP/UL-MAP DL-MAP (downlink map) m8 tri vj tri cult cac burst chira trong Downlink Zones N6 gem s6 cac downlink burst, (10 dii cis chang theo ca huang thoi gian (=symbol) vi tin s6 (= subchannel) UL-MAP (uplink map) Quay truyin nhu burst du tien trong duting... lieu 6 mai cum trong cac ky hieu le va chin duqc bieu di& nhu trong hinh 2.16 0 0 00 00 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 00 00 0 • 0 0 • Cie kl hiW chin Cie Id NW WI 86ng arm mei Nu Sting wow eon ha Mu H'nh 2.16 Kenh con pht2n kip an se DL i Ke hooch sip xep isi duqc se dung de nhom cite cum sao cho mai nhom duqc ciu thinh t>Y cac cum duqc ph8n b6 lchip khong gian song mang con MOt kenh con trong mOt them... de hieu qui han tong tip hqp da dutmg, trong khi yen duy tri tfnh trqc giao cia cic song mang con Hlnh 2.10 bieu clan du frac icsr hieu OFDM trong mien thin gian 41 ► - INE Ts 4 ► Hinh 2.10 Cite tnic man thol gian ctia kit hieu OFDM b Man tin Iwo Imre pc 1 ON Mot w^^ OS W dif Binh 2.11 M6 td tan so OFDM Phan Tien Ting MSV: A13162 Trang 24 CAC KT THUAT SLY DUNG TRONG WiMAX LOp vet lg mks WirelessMAN-OFDM... OFDM co the duqc that hien hieu qui vei bien tt61 Fourrier nguqc nhanh (IFFT), mil cho phop mOt s6 luqng 16n song mang con (len tai 2048) v6i dO phitc tap thip Trong mOt he th6ng OFDM, tili nguyen khit dung trong mien then gian la cic hieu OFDM vi trong mien tin s6 la cic sting mang con Cic tai nguyen thbi gian vil tin s6 c6 the duqc sip xep thrinh cic kenh con de oip phit cho tong nguei so dung Da truy... deg FDD va TDD U'u diem cua phuang phap My lit cho phip linh hoot thay dei de rong bang ten len hoac xu6ng vi vay c6 the thay del the dO phat hoic thu dtt lieu chu kh8ng phai la c6 djnh nhu trong ADSL hay trong CDMA Trong Wi-Fi thi tat ca cac tram deu truy nh$p met each ngiu nhien den diem truy cep AP, vi vey m8 khoang each khac nhau to mai nut den AP se lim giam thong luqng cua mang Nhung b 16p MAC ctla . SIT DUNG TRONG WiMAX OFDM hi mOt ding nghe chia TIM bang tan thlnh de bang nhe hon .Trong WIMAX then chuan 802.16d, dit ap dung ding nghe ntly. VI v(ty WIMAX fixed c6 the host dOng duqc trong. true mang truy cep WiMAX se duqc tr1nh bay 6 chuong tiep then. Phan Tien Tang MSV: A13162 Trang 16 CAC KT THUAT Sir DUNG TRONG WiMAX CHMING 2: CAC KT THUAT SlY DUNG TRONG WiMAX 2.1. Ky thuet. being tin thtyc ii xuit cho WIMAX win thi gtdrt Cac bang tan dirge Diln dart WiMax trong xem xdt va v$n dung ca quan quip 19 tan so cac nu6c phan b6 cho WiMax la: — Bang tin 2,3-2,4GHz