Mang tu td chirc (SON) hay con duac goi la mang tu tdi uu da nhan duoc nhieu quan tam trong nganh cdng nghiep di ddng, SON la giai phap hieu qua de tdi uu hda co sd ha tang hien cd, giai toa ap luc canh ttanh. ddng thdi duy tri chat luong tta: nghiem (QoE|
khi luong thue bao gia tang vdi cac iing dung thoai va du heu ngay cang phd bien Dac biet. khi cac nha khai thac hien nay phai ddi mat vdi nhung thach thiic tiong viec tnen khai raang LTE, su phiic tap ciia cac cdng nghe vd tuyen va cac mang khdng ddng nhat trong khi dam bao tan dung hieu qua cac khoan d^u tu 2G va 3G cua minh thi giai phap tdi uu the he moi ngay cang cd vai ttd quan ttong va can thiet.
CAC T H A C H THliC T R O N G T O I U^U HOA M A N G H I E N NAY
S l / khong dong nhat trong cac mang truy nhap vo tuyen hien thdi (RAN)
Nhu cau su dung dil lieu ciia thue bao ngay cang gia tang - Dap img duoc nhu cau nay ngay cang kho khan hon vi viec su dung
nay la rat khdng ,„;«, ddng deu, Trong «*
mdt nghien ciru duoc thuc hien boi Viavi Soluhons^'^.
danh gia each thirc sit dung dii lieu duoc phan bd tten toan mang. Mang duoc chia thanh cac
T y l e tren tong dien tich
d 50m2 xep canh nhau va tdng sd sii dung du lieu ciia tat ca cac thue bao ttong mdi d duoc tdng ket. Hinh 1 cho thay nhu cdu ddi voi dii lieu duoc phan phdi giua cac d khac nhau. Mdt nira ttong sd cac dti lieu duoc heu thu chi chiem 0,35% dien tich dia ly cua mang, su khdng ddng nhat cua nhu cau cd nghia la mat dd cac ham phat sdng ciing se ttd nen khdng ddng nhat Thdng thudng. mdt nha khai thac se sir dung cac giai phap mang hon hop (HetNet) v6i nhung ttam micro, pico va ttong toa nha (inbuilding), Dieu nay ciing lam tang them cac thach thirc ttong viec quart ly va toi uu hda nhieu lop mang Viec tham sd hoa danh cho mang RAN khdng dong nhat nay de hd tto cho sd luong thue bao khdng dong deu va bien ddng. lam cho cac thach thiic toi mi hda ldn hon bao gio hdt
Tuy nhien, su khdng ddng nhat ma mdt nha khai thac mang phai xii ly khdng chi la su khdng ddng nhat ve nhu cau theo vi tri ma cdn xuat hien ca ttong rmen thdi gian, voi nhu cau ve cac dich vu dao ddng tiong ngay va ttong tu^n, vdi nhiing thay ddi ldn ve miic sir
9 0 % du lieu duoc tieu thu trong vong chua day 5 % dien ticti
5 0 % dQ lieu dixx; tieu thu it hm 0 , 3 5 % dien tich
COV U t u C l ' . CCUl..": C O I X ' . s ; M f f - , 1 M W i ICOCifOMDOaiWl.
Ty le dien tich dia ly Hmh L Su khong d m g nhat ve nhu cau theo VI tn.
I T ? ! TAD rHT rMTTRTTKV 1 ^ 1 2 . 2 0 1 5 1
CONG NGHE VIEN THONG
dung du l i ^ ttong mdt khoang thdi gian la mgt vai phiiL Nhu c5u phat tnen khdng ngimg dan 6.6n viec mang vo tuyen RAN ddi hoi dung lupng nhieu hon.
Ngoai ra cdn eo su khdng dong nhSt theo thue bao;
thue bao cd the duoc chia thanh eac nhdm, nhung I m6i nhom deu co muc dp sii dimg dieh vu eua rieng ho ciing nhu nhu eau ve tai nguyfen mang, nhu cau chSt lupng dich vu (QoS) tdi thieu, dii plu, va gia tn dem lai cho nha khai thac.
S l / phan tach cua mang RAN
•fe)ng eac mang the h$ tiep theo, thu thap thong tin ve dieu kien o nhieu diem quan ttpng dugc dua la boi cac ySu cau ve tinh can bing de xu ly nhiing bien dpng ve nhu eau, tbieu co so ha tang, va du phdng dieh vu mdi. Giam thoi gian tr§ trong lien lac tCt thi^t bi nay ^ n thiet bi Khac se lam mang tro n6n viiag chac hon d^ cd thd dap iing nhu eau cua cac iing dung chuyen n ^ 6 p nhu cac dich vii khan cap, va cudi cimg la yeu cau tdi uu hoa de dat dupc miic dp phuc vu tdt nhat tren mot so tai nguydn su dung nhat dinh. Nhiing ihay doi trong Tmh viic nay dan den su phan tach giiia SON trong mang RAN va tdi im hoa ttong mang loi, va ngay ca tmng tam du lieu, se bat ^ u hi pha vd va linh vue nay se ddn nlian mpt su ehi^en ddi theo huong end-to-end SON.
3GPP da phat tri^n thanh mpt he sinh thai nham dua ra mdt su ket hgp ma cac NEMs va cac ben thii ba dd cung cap mpt loat tdi uu hda va cac giai phap SON dua tren mpt loat cac phuong phap tiep can. Moi phuong phap deu co diem manh va diem ydu, nhimg su thay doi ban chat tu nhien cua cac mang ngay nay lai la mpt cohdi de dua vi6c toi uu hda mang RAN den cSp do eao ban.
C A C P H l / O N G P H A P T I E P C A N T O I U*U S O N K H A C N H A U
Hipn cd nhieu phuong phap nhim tiep can SON de giai quydt nhiing thadi thiic ma nha khai thac phai ddi mat.
D i ^ v£io phan hoi hoac dUa vao phan doan Cach tiep can dua vao phan hoi eo dac tnmg la nhiing thay ddi dugc thuc hien true hep tai mang va tae ddng dugc danh gia trong each thw: hien cac thay ddi true tiep tai mang. Phuong phap tidp nay kha mat thoi gian va dd hi l6i vi chiing dua Q:en loi h$ thdng hon la tinh trang edu hinh tdt hoa Trai nguoc voi each tiep can nay la tdi uu hda dua tren du doaiL Cach tidp can thu hai ray cd dac tiung la su tac ddng ciia cac du doan dugc danh gia trudc khi co bat 1^ thay ddi nao dupc thuc hien trong mang. Phuong phap nay phu thupc vao vide cd mdt each dang tin cay dd mo hinh hda mang va md phong tac dpng ciia nhiing thay ddi duoc thue bieiL
DUa t r e n thong ke hoac lay t h u e bao lam trong t a m
Mang RAN hi$n dai e6 mdt loat phep do dac Hi xa ed sin de tao dieu kien cho viec quan ly va khai ttiae mang, phan tich hieu suat va tdi uu hda. Mot giai phap tdi uu hda ndi chung se su dung mpt sd thdng tm nay, vi dil, lam CO sa de du doan tac ddng eua thay ddi hoac dd danh gia eac tac dpng trong mot he thdng dua trdn thdng tin phan hot Cd nhidu loai dii lieu khac nhau Loai dau tien la tap hgp dii lieu thdng ke nhu sd lieu tnmg binh va sd lugng tren mdi cell NodeB, va khoang ttidi gian. Loai cdn lai, la dii lieu tap hop nhiing gi mdi thue bao trai n ^ e m trong sudt mdi cugc gpi thoai hoae ket ndi du lieu. Loai thit liai nay dugc ggi la dii lieu huong vd thue bao.
Phan t a n / T a p t r u n g / L a i ghep
SON phan tan [DSON] duoc dae trung boi viec thuc hien thuat toan hoac Kha nang thu thap thdng tin tai timg thidt bi mang; vi du trong eNodeB. Ngugc lai, SON tap trung (CSON) nhan bidt dupc eac thdng tin tdn tai tai tnmg tam ( ^ mang.
DSON cd mdt lgi the vi nd tdi ttiidu hda nhu eau ttuyen du lieu tren mang. Didu nay thudng lam giam ehi phi truydn tai va chu k$ thdi giari Nguoc lai, CSON cung ed mgt loi the vi nd ed the cau hinh lai cac khia
TAP CHI CNTT&TT KY 1 (12.2015) 2 3 I
7
CONG NGHE VIEN THONG canh cua mang md cd it thay ddi tai timg vi tri.Khi cac mang RAN tidn ldn SG, kha nang didn toan di ddng (MEC-Mobile Edge Computing) se dupc chudn hda. Didu nay sd md ra viee phan phdi cae img dung DSON cho ben tiiu ba ngoai NEMs. Tai thdi didm nay, se cd mpt su chuydn tidp ddn SON mang nhidu tinh lai hon (HSON). Mang RAN duoc tidn hda va ao hda ttong cac mang SG s6 duoc dae tnmg bdi cac tham sd mdi ma SON cd the kiem soat, chang han nhu chia tacii chiic nang giiia eac don VI thidt bl tii xa va d tnmg tam, vide su dyng cac md hinh truydn dan kdt hop, va vi$e phan bd bang thdng kdt ndi giQa eac nut, fronthaul, va backhaul. Viee ttang bi nay se tao ra mdt luong ldn du lidu eho tdi uu hda va do dd mdt thanh phdn dupc phan tan cho HSON sd ttanh duoc viec tmydn tai mdt lupng ldn dii lieu ddn mdt he thdng SON tap tiimg.
Cae mang ludi ngay cang bidn ddng va Miong ddng nhat dang ttd ndn phd bidn vdi dac tiung bdi su tiiay ddi tham sd, nd cd tae dung phu ma khd ed the du doan khi khong duac md hinh hda tinh vi. Didu nay cd nghia lang mpt thanh plian CSON se bd sung eao thanh phan DSON va tao la mdt kha nang tdi uu hda mang tinh lai ed hidu qua.
CO HOI MOI CHO TOI l/U THE HE MOI - LAY THUE BAO LA TRUNG TAM O MljTC O p CAO
Di tit cac trifdng hcfp cu the, ap dung vao thue bao
Theo tiiiydn thdng, tdi uu hda SON da tap tiung vao eac trudng hgp su dimg rieng bidt ma giai quydt cae khia canh cu thd ciia van dd chat luong. Vi du, quan hd giiia cac cell Ian can tu ddng (ANR) la ed Uen quan vdi viec dat duoc cac danh sach quan he tdi uu.
Danh saeh quan hd cdn duoc hoan chinh de mdi UE ed mdt cell dich dd chuydn giao phii hpp ttong moi tinh hudng. Ddng thdi, eac danh sach khdng nen qua dai ma sd lugng cd thd khai bao duoc da hdt, hoac dd UE mat qua nhidu thdi 0an tun kidm eac muc tifeu chuydn
giao tdt nhdt. Tuong tu nhu v$y, tdi uu hda vimg phii va dung lupng mang (CCO) cQng can dugc can nhdc dd can bang vdi nhau, giiia vimg phu dia ly eiia mang va dung luong dd phuc vu thoai va dii Iidu cho ngudi dimg.
Tuy nhien, giao dien vd tuydn eua RAN la phi tuyen tinh va phan img vdi cac bidn ddi hoac thay ddi cae tham sd; ngay ci nhung thay ddi nho ttong cac thdng sd mang cd thd ed vo sd eac hidu img. Vi du, ngdng cao ang-ten len hoae tang cdng suat tin hieu tham ehidu ttong LTE s& md rdng nhidu thidt bi su dung dieh vu tir cell dd. Su thay ddi nay se gay ra mdt su thay ddi trong ty Id tin higu nhidu (SNRl cho nhieu thud bao. Su thay ddi nay khdng ehi danh eho cac thud bao dang sii dung dich vu tir cell nay so vdi tmdc khi thay ddi. Do cac thud bao nay edn dupc phuc vu bdi cac cell khac, nd cung se thay ddi cho cae thue bao khac ma cd ciing su phuc vy eiia cell dd ed chia se tai nguydn eho eac thue bao ttSn.
Su thay ddi ttong cae dae tinh RF cho eac thue bao se thay ddi nhiing ttai nghidm tten cae dieh vu ma hp su dung. Tde dd dii heu cd tiid bi anh hudng vi nhidu IJ do. Vi du, thay ddi tde do cd thd lien quan tdi nhiing thay ddi SNR, nhung eiing cd the vi miie dd nghen eua cell khi cae cell ttd nen tae nghen it hogc nhidu hon,
Mdt ket ndi duge thidt lap cho mdt cupc goi VdLTE cd the su dung cae bd codec khae nhau vdi mpt su thay ddi Iidn quan ddn chat luong thoai. Ti Id phi6n thiet lap thanh cdng eung se bi anh huong. Tdt ca nhiing yeu td nay TO the tae ddng ddn su hai ldng ciia khach hang.
Thidt bi tai dia diem dd cd thd khOng cdn duoc hd Oy VoLTE va ed thd phai chuydn hudng tid lai mang 2G/3G dd su dung dieh vu thoai Nguoc lai, dieh vu VoLTE cd Old ed sin noi ma tiudc day nd khdng cd. Tac ddng cua sir thay ddi se Miac nhau theo thud bao tiiy theo dieu kien vd tuydn cua hp va nhung dich vu ma ho dang tmy cap.
cac tae ddng cua su thay ddi cQng se thay ddi theo thdi gian ttong ngay vdi md hinh luu lugng chuydn dich theo thdi gian ttong ngay.
2 4 TAP CHI CNTT&TT KY 1 (12.2015)
CONG NGHE VIEN THONG
Hinh 2. TSc dOng ti&n an trfin nnOt thue bao tCrmot sythay doi tham so.
Hinh 2 cho ttidy cac tae dpng tidm an phiic tap tt6n mdt thud bao tii mpt su thay ddi cac thdng sd. Tac ddng vao nhung tinh nSng eiia dieh vu va ttai nghidm cua mdi thue bao la vd cimg quan ttpng. Tae dpng nay phu thude vao eac dlcti vu dugc thud bao su dung va cae do dae vd chat lugng dich vu dat dupe cho mdi dich vu vd tdc dd dii; lidu, kha nang tmy iihg.p, va kha nang duy tri dich vu. Didu nay dugc minh hpa boi mau xanh la eay ttong hinh. Nhiing do dac vd dieh vu nay se lan lupt dupe quydt dmh bdi mgng vd tuydn bao gdm ea cuong dp tin hidu va nhidu SNR ma diung lai duge quydt dinh bdi cell phuc vu va su can nhidu tir ngudi diing trdn eac cell khac.
Bat ky su thay ddi thdng sd nao ddu cd tiid anh
hudng ddn moi thanh phdn eua hd thdng phiic tgp nay, bat ky thud bao ndo, va eudi eimg la chat lupng cua toan bp mang ludi, bao gdm ca nhiing khia canh cua hidu sudt, ma lihi khai thac quan tam ntiidu nliat. Didu nay cd nghia la mdi thud bao phdi dupe xem xdt moi tac ddng tdng the cua su thay ddi cdn dugc ndm bdt chinh xaenlidt.
Hirih 3 va 4 cho thdy tac ddng cua vide thay ddi cdng sudt phat va dd nghidng ciia ang-ten tai ba ttam. Cac tac dpng ciia nhiing thay ddi nay da dugc lam mdu eho tdt ea eac thud bao dang hoat ddng ttong mang ttong mdt khoang thcri gian eu thd. Cac sd Ueu eho tiidy tac ddng ttdn mdi thu6 bao nhan dugc cudng dd tin hieu va tdc dd truyen tung khdi burst. Mau do chi ra mdt su suy giam ttong phdp do nay, ttong khi mau xanh la cay eho thdy mot su cai thi6n. Mau xam cho thay khdng ed su thay ddi.
Nhin vao cudng dd tin hi§u lihan dupc, ttong khi ed mdt sd khu vuc chimg duoc cai thien hay ndi chung la suy giam, ed mdt su pha ttpn cua ci vide eai thidn va suy giam cho ea hai do dac ttdn toan bd khu vitc. Su thay ddi md hinh 6 day xuat hidn trude hdn la mpt su
Hmh 3 Anh huong cua thay doi acng dO tin hieu Hinh 4: Anh huong cua thay d6i tdc do ttuyen tOng khfii burst.
TAP CHI CNTT&TT KY 1 ( 1 2 . 2 0 1 5 ) I 2 5 I
1
CONG NGHE VIEN THONGsuy gidm; cudng dp tin hidu nhan dupe du doan la xdu hon vdi cae thud bao duge hi$n ldn bang mau do. Nguoc lai, vdi eimg cdu hinh, Hinh 4 cho thay rdng tde dd tiuydn khdi burst thudng dugc tang ldn ddi vdi hdu nhu tat ea eac Ihud bao. Didu nay la chinh xac bdi vi cudng dp tin hidu thap hon. Mdi tnidng vd tuydn "saeh" hon vdi cudng dp thdp hon va do do, it nhidu hon. Cdng suat thap hon dd phuc vu cac thue bao cd nghia la ed nliieu cdng sudt du cho vide tiuydn da U^u huu ich tdi thue bao. Nhidu thdp hon cd nghia la cd nhieu tin hidu huu ich hon vdi nhidu ndn cd sdn, cho phep sd dung mdu dieu chd va ma hda eho cac tdc dd cao ban.
Nhidu ydu td quydt dinh vide ttai nghi$m thue bao gia tang hay sut giam, bao gdm ca cudng dd cua eac ceU phuc vu va cac ceU gay nhidu. Nhiing ydu td nay, ddn lugt nd, dupc xac dinh bdi ban chdt chinh xac cua mdi trudng vo tuydn phiic tgp tgi dia didm dd. Cdu tnic hat ttong img phd vdi nhiing thay ddi din ddn viee thidt l§p tdi uu hda dua tten cac ydu td tiidng ke dai di$n eho hidu sudt mgng la rdt khd khan dd dat duoc vdi dil dd chinh xac; eac md hinh tiidng kd don gian la khdng tiid nam bat cau tnic hat nay.
Dd cdi thidn dang kd chat lupng mang, mdt nha khai thac phai ndm bat dupc cae tac ddng cua su thay ddi eac thdng so va dugc
hai dang kd ddn hidu sudt mang, ngudi ta phai sii dung mdt phuong phdp dua tten du doan.
Viavi da n h ^ tiidy rang cde phuang phap tidp cfin hudng tdi thud bao cd tiid dua ra du doan rdt chinh xae vd tae ddng cua thay ddi tham sd. Khi mang dupc hidu tdi mdc dO cua cae thud bao, tiiud bao ed thd dupc dinh vi dia ly va vi tri su dung lam eho tac ddng dugc tinh toan chinh xac hon. De minh hoa didu ndy, mdt tdi uu hda hudng thud bao da dugc thue hidn ttdn mdt cum 3G va phan phdi tich luy cua tdc dd tmydn khdi bdt ngudn tii nhdm eac thud bao ea sd tiudc khi thuc hidn bdt ky Oiay ddi nao. Su phan bd ttiong hi cQng dupc tinh toan eho mang ttong tinh trang mdi nhung tmdc bdt ky su tiiay ddi da dupc thuc hidn. Cie khuydn nghi da dupe trien khai sau dd cho mang vd cung mdt phan phdi duoc do ti^ng mang tdi uu.
Hinh 5 cho thdy rang tdc dp Quyen khdi dugc cai thien sau Khi thay ddi; tten thuc te, tde dd tang ldn tdi tnmg binh 38% cho mpt 1 dB cai thien SNR. Thfim ehi thil VI hon la cae md hinh du bao hudng thud bao da cd thd danh gia chinh xae h$ thdng phan phdi ciia tde dd tmydn khdi se thay ddi ra sao, trudc khi thay ddi thuc td. Day la mdt kha nang quan ttpng eua each tiep can huong thue bao. Phuong phap nay rdt cd gia tri de thuc hifen dupc nhieu ttiay ddi thdt dd hon so chudn bi de thay ddi
dang ke tii tham sd hidn tai. Didu do ed thd rat nguy hiem khi thue hidn each tidp can dua tt6n thdng tin phan hdi;
tai tham sd triet dd cd thd ed tac ddng dang kd den hidu sudt mang, ea tich cue va tidu cue. De ttanh nguy co thidt
Toe do truydn theo khfii duDc cai thien sau thay d6i
Thay ^ i trong toe do truydn theo kh6i doc dudoan chinh x ^ TficdO
tnjygn theo khfii 3^ 3.5
2.S i 1.5
o.s
1
improved burst rate after
change
Change in
burst rate 1 accurately / predicted jf
0.4 0.6 Hmh 5: Dydo^n chinh xac.
2 6 TAP CHT CNTT&TT KY 1 (12.2015)
CONG NGHE VIEN THONG
^1
voi phuang phdp tidp can khae. Nd cung eho phdp thuc hien nhihig su danh ddi de dgt dugc mue tidu phil hgp vdi eac muc hdu kinh doanh cua nha khai thac.
Mgt giai phap SON linh hogt phai cd tinh ttiich nghi cao nen nd ed thd didu chinh dd phu hpp vdi nhiing thuc td kinh doanh khac nhau. Vi du, giam cac cugc ggi ed tiid do mdt logt cac ydu td gdp phdn nhu sdng ydu. Sir can tiii$p qua muc, mat sdng d khu vuc lan can. hoac cac thdng sd di ddng cdu hinh saL Ndu su dung SON truyen thdng se ydu cdu ttien khai mdt so tmdng hgp sit dung, va se van harih de tim mdt giai phap. Cd mdt nguy co la cac giai phap sir dung dua tten tiing trudng hgp cd thd khdng lam vide vdi nhau;
neu danh saeh eac khu vuc lan can dugc tdi uu hda cho cac thiet ke vd tuyen hi^n tgi, ma thidt kd vd tuydn cd tiie duoc tiiay ddi ttong phgm vi va Kha nang tdi uu hda, lam cho danh sach cae Khu vue lan can khPng cdn tdi uu.
Khac phuc van dd nay ddi hdi mpt each tidp can ma khdng tap trung vao mdt khia canh cua hidu sudt mang tai mdt thdi didm. Md hinh hda eac tac dpng tdng thd cda tham sd thay ddi ttdn mang, bao gdm cac dac didm vP tuydn eho mdi thuS bao, cac tac ddng ddi vdi tinh di dpng, va eac biSn phap QoE cap cao hon, cho phep danh gia toan didn hon vd cac tac ddng cua nhiing thay ddi duoc de Midt. Didu nay s6 dat dugc mgt thidt kd chat lugng eao hon. Su dung tdi im hda hiKing tdi thud bao kdt hgp vdi md hinh du bao va xem xdt tae ddng tdng thd cua nhiing thay ddi dugc thuc hiSn.
Cat gidi phap toi u^ SON cung ton tai Trdn thi tradng cd mdt loat cae giai phap SON khae nhau, ed nhiing giai phap khdng hudng ve thue bao va nhieu NEMS eung cap giii phap DSON. DSON dua ra viec ra quydt dinh vd nhiing tiiay ddi tdi uu hda eho mgng Uln egn, dien hinh la a eNodeB. Khi ed nhiing giai phap SON khong hudng vd thue bao cimg hoat
ddng ttong mpt mang, cd nhtmg ca hdi dd nhan ra tidm nang day du cua cac cai thien hi§u sudt vdi mot phuong phap tiep can hirdng vd thud bao su dimg cae bidn phap du doan
SON tdi uu hda hudng tdi thud bao phai cimg tdn tgi vdi cde giai phap hidn cd nay. Nd phai cd kha nang quan ly nhung thay ddi duoc thuc hidn mdt each ddc lap vd cQng phai cd kha nang gia tang gia til dang kd cung vdi cae giai phap cd sdn tir trudc. Thii hai, giai phap SON the he ke tidp phai ed kha nang hoan thanh muc tieu thue su ciia SON: chon thay ddi cdu hinh tdi da hda loi ich va thuc hidn dieu chinh bdng tinh toan hidu sudt ehinh xac phd hgp voi cac muc tieu kinh doanh cua nha khai thac mang.
KET L U A N
Dua ra du doan ve each thiic ma mang se thay ddi de dap img vdi nhiing bidn doi vd tinh ttang cua nd la phuong phap tdt nhdt dd eai thien liidu suat RAN.
Viae tap trung vao cae thue bao cd the giup ndm bdt duac su phuc tap, khPng dong nhdt, va phi tuydn tinh cua RAN ngay nay. Md hinh hda du bao lay thue bao la ttgng tam khdng chi dd cai thi$n hi$u nang, ma edn true tidp eai thien ttai ngbifm thu6 bao va phu hgp voi mue tidu Kmh doanh cua nha khai thac.
Vi nha khai thac ggp nhieu van dd hdn quan den su phiic tap ngay cang tang cua nhidu dich vu ma hg eung cap, nliieu nha chuydn giao, tai san ca so hg tang cao khong ddng nhat, tdi uu hda hudng ve thud bao la mpt tai san ed gia tn quan ttong ttong kho cac giai phap quan ly hieu sudt mang.
Tai lieu t h a m khao
[1]. Viavi Solutifflis (2015), Harnessing SJyscnberCentic Qjtimization for the Next Generation of Self-Organisng Networks, http://www.viavisolutions.com/.
[2], COMfT Corporation (2015), Khai th^t&uuhoa lay thue bao ldm trong tSm cho thS h$ k^ tt^ cua dc mang livi tu /o chifc. http://www.comitcorp.edu.vn/.
TAP CHi CNTT&TT K Y I (12.2015) I 2 7 i
