Tim Hieu Mang Lte Va Mo Phong Qua Trinh Chuyen Giao Tren Omnet

MC LC

DANH MC HNH V

1

MC LC BNG BIU

2

DANH MC VIT TT

3GPP Third Generation PartnershipProject

D n cc i tc th h th ba

AAA Authentication, Authorizationand Accounting

Xc thc, cp php v tnh cc

ACF Analog Channel Filter B lc knh tng tACK Acknowledgement S bo nhnACLR Adjacent Channel Leakage Ratio T l d knh ln cnAMBR Aggregate Maximum Bit Rate Tc bt ti a cp phtAMD Acknowledged Mode Data D liu ch bo nhnARP Allocation Retention Priority u tin duy tr cp phtCDM Code Division Multiplexing Ghp knh phn chia theo mCDMA Code Division Multiple Access a truy nhp phn chia theo mDL Downlink ng xungUL Uplink ng lnDL-SCH Downlink Shared Channel Knh chia s ng xungDPCCH Dedicated Physical Control

ChannelKnh iu khin vt l ring

E-UTRAN

Evolved Universal TerrestrialRadio Access

Truy nhp v tuyn mt t toncu pht trin

FFT Fast Fourier Transform Bin i furier nhanhFS Frequency Selective La chn tn sGERAN GSM/EDGE Radio Access

NetworkMng truy nhp v tuynGSM/EDGE

GGSN Gateway GPRS Support Node Nt cng h tr GPRSGW Gateway CngHARQ Hybrid Automatic Repeat Quest Yu cu lp li t ng h hpHO Handover S chuyn vngHSDPA High Speed Downlink Packet

AccessTruy nhp gi ng xung tc Cao

HS-DSCH

High Speed Downlink SharedChannel

Knh chia s ng xung tc Cao

HSCSD High Speed Circuit SwitchedData

S liu chuyn mch knh tc Cao

HSPA High Speed Packet Access Truy nhp gi tc caoHS-PDSCH

High Speed Physical DownlinkShared Channel

Knh chia s ng xung vt ltc cao

HSS Home Subscriber Server My ch thu bao thng trHS-SCCH

High Speed Shared ControlChannel

Knh iu khin chia s tc cao

HSUPA High Speed Uplink PacketAccess

Truy nhp gi ng ln tc Cao

3

IP Internet Protocol Giao thc InternetLTE Long Term Evolution S pht trin di hnMAC Medium Access Control iu khin truy nhp mi trngMAP Mobile Application Part Phn ng dng di ngMBMS Multimedia Broadcast Multicast

SystemH thng pht qung b a ima phng tin

MBR Maximum Bit Rate Tc bt ti aMCH Multicast Channel Knh a imMCS Modulation and Coding Scheme S m ha v iu chMGW Media Gateway Cng phng tinMIMO Multiple Input Multiple Output a u vo a u raMME Mobility Management Entity Phn t qun l tnh di ngMPR Maximum Power Reduction S gim cng sut ti aOFDM Orthogonal Frequency Division

MultiplexingGhp knh phn chia tn s trcGiao

OFDMA Orthogonal Frequency DivisionMultiple Access

a truy nhp phn chia tn s trcGiao

PAPR Peak to Average Power Ratio T l cng sut nh ti trung bnhPAR Peak-to-Average Ratio T l nh-trung bnhPC Power Control iu khin cng sutPCCC Parallel Concatenated

Convolution CodingM xon ghp song song

PDN Packet Data Network Mng d liu giPDU Payload Data Unit n v d liu ti tinPDSCH Physical Downlink Shared

ChannelKnh chia s ng xung vt l

P-GW Packet Data Network Gateway Cng mng d liu giPHICH Physical HARQ Indicator

ChannelKnh ch th HARQ vt l

PHY Physical Layer Lp vt lPLL Phase Locked Loop Vng kha phaPLMN Public Land Mobile Network Mng di ng mt t cng cngPMIP Proxy Mobile IP IP di ng y nhimPN Phase Noise Ting n phaPRACH Physical Random Access

ChannelKnh truy nhp ngu nhin vt l

PRB Physical Resource Block Khi ti nguyn vt lPS Packet Switched Chuyn mch giPSD Power Spectral Density Mt ph cng sutPSS Primary Synchronization Signal Tn hiu ng b s cpPUCCH Physical Uplink Control Channel Knh iu khin hng ln vt lPUSCH Physical Uplink Shared Channel Knh chia s hng ln vt lQAM Quadrature Amplitude iu ch bin cu phng

4

ModulationQoS Quality of Service Cht lng dch vSCM Spatial Channel Model Ch knh khng gianSC-FDMA

Single Carrier FrequencyDivision Multiple Access

a truy nhp phn chia tn s nsng mang

SCH Synchronization Channel Knh ng bSCTP Stream Control Transmission

ProtocolGiao thc truyn dn iu khinlung

SDU Service Data Unit n v d liu dch vSFBC Space Frequency Block Coding M khi tn s khng gianSFN System Frame Number S khung h thngSGSN Serving GPRS Support Node Nt h tr dch v GPRSS-GW Serving Gateway Cng phc vSIB System Information Block Khi thng tin h thngSIMO Single Input Multiple Output n u vo a u raSMS Short Message Service Dch v bn tin ngnSNR Signal to Noise Ratio T l tn hiu trn nhiuSON Self Optimized Networks Mng t ti uSR Scheduling Request Yu cu lp lch biuSRB Signaling Radio Bearer Phn t mang bo hiu v tuynSRS Sounding Reference Signals Tn hiu chun thm dSU-MIMO

Single User Multiple InputMultiple Output

n ngi dng - a u vo au ra

S1AP S1 Application Protocol Giao thc ng dng S1TACS Total Access Communication

SytemH thng truyn thng truy nhpton phn

TD Time Domain Min thi gianTDD Time Division Duplex Song cng phn chia thi gianTD-LTE Time Division Long Term

EvolutionPhn chia theo thi gian LTE

TD-SCDMA

Time Division Synchronous Code Division Multiple Access

Phn chia theo thi gian a truynhp phn chia theo m ng b

TPC Transmit Power Control iu khin cng sut phtTRX Transceiver B thu phtTTI Transmission Time Interval Khong thi gian truynUDP Unit Data Protocol Giao thc n v d liuUE User Equipment Thit b u cuiUL Uplink ng lnUL-SCH Uplink Shared Channel Knh chia s ng lnUMTS Universal Mobile

Telecommunications SystemH thng thng tin di ng toncu

UTRA Universal Terrestrial RadioAccess

Truy nhp v tuyn mt t toncu

5

UTRAN Universal Terrestrial RadioAccess Network

Mng truy nhp v tuyn mt tton cu

VoIP Voice over IP Thoi qua IPWCDMA Wideband Code Division

Multiple Accessa truy nhp phn chia theo mbng rng

WLAN Wireless Local Area Network Mng ni b khng dy

6

Tm hiu mng LTE v m phng qu trnh chuyn giao trn Omnet++

CHNG 1 TNG QUAN V TI

1.1 L do chn ti

Thng tin di ng l mt lnh vc rt quan trng trong i sng x hi. X hi

cng pht trin, nhu cu v thng tin di ng ca con ngi cng tng ln v thng

tin di ng cng khng nh c s cn thit v tnh tin dng ca n. Cho n

nay, h thng thng tin di ng tri qua nhiu giai on pht trin, t th h di

ng th h 1 n th h 3 v th h ang pht trin trn th gii - th h 4.

1.2 Mc tiu ca ti

Tm hiu trnh by v xu hng cng ngh, qu trnh pht trin ca mng

thng tin di ng 1G, 2G, 3G, LTE v cu trc mng LTE cc k thut s dng

trong h thng mng LTE. Trnh by cc khi nim chung v qu trnh handover

ca h thng di ng, trnh by chi tit v qu trnh handover trong h thng thng

tin di ng 4G vi phn miu t tp trung vo qu trnh chuyn giao dc gia cc

mng trong h thng 4G. M phng c qu trnh chuyn giao trong mng LTE.

1.3 Gii hn v phm vi ca ti

ti tm hiu cu trc mng, cc k thut s dng trong h thng mng, cc

knh, iu khin cng xut trong mng LTE. Tm hiu qu trnh chuyn giao, cc k

thut chuyn giao trong mng LTE hay LTE sang 3G

S dng phm mm m phng omnet++ m phng qu trnh chuyn giao

ca mng LTE.

1.4 Ni dung thc hin

H thng 4G c xy dng nhm chun b mt c s h tng di ng chung

c kh nng phc v cc dch v hin ti v tng lai. C s h tng 4G c thit

k vi iu kin nhng thay i, pht trin v k thut c kh nng ph hp vi

mng hin ti m khng lm nh hng n cc dch v ang s dng. thc hin

7


iu , cn tch bit gia k thut truy cp, k thut truyn dn, k thut dch v

(iu khin kt ni) v cc ng dng ca ngi s dng

Ni dung thc hin/nghin cu c th nh sau:

- Cc c im k thut, cu trc mng c s dng trong mng LTE.

- Cc knh s dng trong E-UTRAN, k thut s dngcho ng ln,

ng xung trong LTE.

- trnh by khi qut v chuyn giao trong h thng thng tin di ng,

chuyn giao gia 3G v 4G, qu trnh chun b chuyn giao, qu trnh

chuyn giao, cc loi chuyn giao, chuyn giao i vi mng LTE.

- Ci t v m phng qu trnh chuyn giao trong mng LTE.

1.5 Phng php tip cn

- Cch tip cn : Nghin cu cu trc mng LTE, cc k thut s dng trong

mng LTE, tm hiu phn mm m phng omnet++ v ci t qu trnh

chuyn giao mng LTE trn omnet++

- S dng cc phng php nghin cu:

o Phng php c ti liu;o Phng php phn tch mu;o Phng php thc nghim.

8


CHNG 2 C S L THUYT MNG LTE (4G)

2.1 Gii thiu v cng ngh LTE

H thng 3GPP LTE, l bc tip theo cn hng ti ca h thng mng

khng dy 3G da trn cng ngh di ng GSM/UMTS, v l mt trong nhng

cng ngh tim nng nht cho truyn thng 4G. Lin minh Vin thng Quc t

(ITU) nh ngha truyn thng di ng th h th 4 l IMT Advanced v chia

thnh hai h thng dng cho di ng tc cao v di ng tc thp. 3GPP LTE

l h thng dng cho di ng tc cao. Ngoi ra, y cn l cng ngh h thng

tch hp u tin trn th gii ng dng c chun 3GPP LTE v cc chun dch v

ng dng khc, do ngi s dng c th d dng thc hin cuc gi hoc truyn

d liu gia cc mng LTE v cc mng GSM/GPRS hoc UMTS da trn

WCDMA. Kin trc mng mi c thit k vi mc tiu cung cp lu lng

chuyn mch gi vi dch v cht lng, tr ti thiu. H thng s dng bng

thng linh hot nh vo m hnh a truy cp OFDMA v SC-FDMA. Thm vo ,

FDD (Frequency Division Duplexing) v TDD (Time Division Duplexing), bn

song cng FDD cho php cc UE c gi thnh thp. Khng ging nh FDD, bn

song cng FDD khng yu cu pht v thu ti cng thi im. iu ny lm gim

gi thnh cho b song cng trong UE. Truy cp tuyn ln da vo a truy cp phn

chia theo tn s n sng mang (Single Carrier Frequency Division multiple Access

SC-FDMA) cho php tng vng ph tuyn ln lm t s cng sut nh trn cng

sut trung bnh thp (Peak-to-Average Power Ratio PAPR) so vi OFDMA. Thm

vo , ci thin tc d liu nh.

2.1.1 ng c thc y

Cn th h tip theo ci thin cc nhc im ca 3G v p ng nhu cu

ca ngi s dng. Ngi dng i hi tc d liu v cht lng dch v cao hn. Ti u h thng chuyn mch gi. Tip tc nhu cu ca ngi dng v gim gi thnh (CAPEX v OPEX). Gim phc tp Trnh s phn on khng cn thit cho hot ng ca mt cp hoc khng

9


phi mt cp di thng.

2.1.2 Cc giai on pht trin ca LTE

Bt u nm 2004, d n LTE tp trung vo pht trin thm UTRAN v ti

u cu trc truy cp v tuyn ca 3GPP. Mc tiu hng n l dung lng d liu truyn ti trung bnh ca mt

ngi dng trn 1 MHz so vi mng HSDPA Rel. 6: Ti xung: gp 3 n 4

ln (100Mbps). Ti ln: gp 2 n 3 ln (50Mbps). Nm 2007, LTE ca k thut truy cp v tuyn th h th 3 EUTRA-

pht trin t nhng bc kh thi a ra cc c tnh k thut c chpnhn. Cui nm 2008 cc k thut ny c s dng trong thng mi.

Cc k thut OFDMA c s dng cho ng xung v SC-FDMA c

s dng cho ng ln.

2.1.3 Mc tiu ca LTE

Tc d liu cao. tr thp. Cng ngh truy cp sng v tuyn gi d liu ti u

2.1.4 Cc c tnh c bn ca LTE

Hot ng bng tn: 700 MHz-2,6 GHz. Tc :

- DL: 100Mbps( BW 20MHz)- UL: 50 Mbps vi 2 aten thu mt anten pht.

tr: nh hn 5ms. rng BW linh hot :1,4 MHz; 3 MHz; 5 MHz; 10 MHz; 15 MHz; 20

MHz. H tr c 2 trng hp di bng ln v bng xung bng nhau

hoc khng. Tnh di ng: Tc di chuyn ti u l 0-15 km/h nhng vn hot ng

tt vi tc di chuyn t 15-120 km/h, c th ln n 500 km/h ty bng

tn. Ph tn s:- Hot ng ch FDD hoc TDD.- ph sng t 5-100 km.- Dung lng 200 user/cell bng tn 5 Mhz.

Cht lng dch v :- H tr tnh nng m bo cht lng dch v QoS.

10


- VoIP m bo cht lng m thanh tt, tr ti thiu thng qua mng

UMTS. Lin kt mng:

- Kh nng lin kt vi cc h thng UTRAN/GERAN hin c v cc h

thng khng thuc 3GPP cng s c m bo.- Thi gian tr trong vic truyn ti gia E-UTRAN v UTRAN/GERAN

s nh hn 300ms cho cc dch v thi gian thc v 500ms cho cc dch

v cn li.- Chi ph: chi ph trin khai v vn hnh gim.

Bng thng linh hot trong vng t 1.4 MHz n 20 MHz, iu ny c ngha

l n c th hot ng trong cc di bng tn ca 3GPP. Trong thc t, hiu sut

thc s ca LTE ty thuc vo bng thng ch nh cho cc dch v v khng c s

la chn cho ph tn ca chnh n. Trin khai ti cc tn s cao, LTE l chin lc

hp dn tp trung vo dung lng mng, trong khi ti cc tn s thp n c th cung

cp vng bao ph khp ni. Mng LTE c th hot ng trong bt c di tn c

s dng no ca 3GPP. N bao gm bng tn li ca IMT-2000 (1.9-2 GHz) v di

m rng (2.5 GHz), cng nh ti 850-900 MHz, 1800 MHz, ph AWS (1.7- 2.1

GHz)Bng tn ch nh di 5MHz c nh ngha bi IUT th ph hp vi

dch v IMT trong khi cc bng tn ln hn 5MHz th s dng cho cc dch v c

tc cc cao. Tnh linh hot v bng tn ca LTE c th cho php cc nh sn

xut pht trin LTE trong nhng bng tn tn ti ca h.

2.1.5 Cc thng s lp vt l ca LTE

Bng 2-1: Cc thng s lp vt l LTE Bng

K thut truy cpUplink a truy cp phn chia theo tn s trc

giao n sng mang (SC-FDMA)Downlink Ghp knh phn chia theo tn s trc

giao (OFDMA)Bng thng 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz,

20MHzThi gian ti thiu 1msKhong cch sng mang con 15KHzChiu di CP Ngn 4.7s

Di 16.7 s

11


iu ch QPSK , 16QAM, 64QAM

Ghp knh khng gian1 lp cho UL/UELn n 4 lp cho DL/UES dng MU-MIMO cho UL v DL

Bng 2-2: Tc t nh ca LTE theo lp

Lp 1 2 3 4 5Tc tnh Mbps

DownLink 10 50 100 150 300UpLink 5 25 50 50 75

Dung lng cho cc chc nng lp vt lBng thng RF 20MHziu ch DownLink QPSK, 16QAM, 64QAM

UpLink QPSK, 16QAM QPSK, 16QAM, 64QAM

2.1.6 Dch v ca LTE

Qua vic kt ni ca ng truyn tc rt cao, bng thng linh hot, hiu

sut s dng ph cao v gim thi gian tr gi, LTE ha hn s cung cp nhiu dch

v a dng hn. i vi khch hng, s c thm nhiu ng dng v dng d liu

ln, ti v v chia s video, nhc v ni dung a phng tin. Tt c cc dch v s

cn lu lng ln hn p ng cht lng dch v, c bit l vi mong i

ca ngi dng v ng truyn TV r nt cao. i vi khch hng l doanh

nghip, truyn cc tp tin ln vi tc cao, cht lng video hi ngh ttLTE s

mang c tnh ca Web 2.0 ngy nay vo khng gian di ng ln u tin. Dc

theo s bo m v thng mi, n s bng qua nhng ng dng thi gian thc nh

game a ngi chi v chia s tp tin.

Bng 2-3: So snh cc dch v ca 3G so vi 4G LTE

Dch v Mi trng 3G Mi trng 4GThoai (rich voice) m thanh thi gian thc VoIP, video hi ngh cht

lng caoTin nhn P2F (P2Fmessaging)

SMS, MMS, cc email utin thp

Cc tin nhn photo, IM,email di ng, tin nhnvideo

Lt web(browsing) Truy cp n cc dchv online trc tuy n, Trnhduyt WAP thng qua

Duyt siu nhanh, ti ccni dung ln cc mng xhi.

12


GPRS v mng 3G.Thng tin cc ph(paid information)

Ngi dng tr qua hoctrn mng tnh cc chun.Chnh yu l da trnthng tin vn bn.

Tp ch trc tuyn, dngm thanh ch t lng cao.

Ring t(personalization)

Ch yu l m thanhchung (ringtone), cngbao gm mn hnh ch(screensavers)v nhc ch(ring tone).

m thanh thc(thu mgc t ngi ngh s), cctrang web c nhn.

Games Ti v v chi game trctuyn.

Kinh nghim game trctuyn vng chc qua cmng c nh v di ng.

Video/TV theo yu cu (video/TV ondemand)

Chy v c th ti video. Cc dch v qung btivi, Tivi theo ng yucu dng video chtlng cao.

Nhc Ti y cc track v ccdch v m thanh.

Lu tr v ti nhc chtlng cao

Ni dung tin nhn Tin nhn ng cp s dngba thnh phn cng nhtng tc vi cc mediakhc.

Phn phi t l rng cacc video clip, dch vkaraoke, video c bnqung co di ng.

M comerce(thng mi qua

in thoi)

Thc hin cc giao dch vthanh ton qua mng ding.

in thoi cm tay nhthit b thanh ton, vicc chi tit thanh tonqua m ng tc cao cho php cc giao dchthc hin nhanh chng.

Mng d liu ding(mobile data

netwoking)

Truy cp n cc mng nibv c s d liu cngnh cch s dng ca ccng dng nh CRM.

Chuyn i file P2P, ccng dng kinh doanh, ngdng chia s, thng tinM2M, di ngintranet/extranet.

13


2.2 Cu trc ca LTE

2.2.1 Cu trc c bn SAE ca LTE

Hnh 2-1: So snh v cu trc gia UTMS v LTE

Hnh trn cho ta thy s khc nhau v cu trc ca UTMS v LTE. Song song

vi truy nhp v tuyn LTE, mng gi li cng ang ci tin ln cu trc tng SAE.

Cu trc mi ny c thit k ti u hiu sut mng, ci thin hiu qu chi ph

v thun tin thu ht phn ln dch v trn nn IP.

Mng truy nhp v tuyn RAN (Radio Access Network): mng truy nhp v

tuyn ca LTE c gi l E-UTRAN v mt trong nhng c im chnh ca n l

tt c cc dch v, bao gm dch v thi gian thc, s c h tr qua nhng knh

gi c chia s. Phng php ny s tng hiu sut ph, lm cho dung lng h

thng tr nn cao hn. Mt kt qu quan trng ca vic s dng truy nhp gi cho

tt c cc dch v l s tch hp cao hn gia nhng dch v a phng tin v gia

nhng dch v c nh v khng dy.

C nhiu loi chc nng khc nhau trong mng t bo. Da vo chng, mng

c th c chia thnh hai phn: mng truy nhp v tuyn v mng li. Nhng chc

nng nh iu ch, nn, chuyn giao thuc v mng truy nhp. Cn nhng chc

nng khc nh tnh cc hoc qun l di ng l thnh phn ca mng li. Vi

LTE, mng truy nhp l E-UTRAN v mng li l EPC.

14


Mc ch chnh ca LTE l ti thiu ha s node. V vy, ngi pht trin

chn mt cu trc n node. Trm gc mi phc tp hn NodeB trong mng truy

nhp v tuyn WCDMA/HSPA, v v vy c gi l eNodeB (Enhance Node B).

Nhng eNodeB c tt c nhng chc nng cn thit cho mng truy nhp v tuyn

LTE, k c nhng chc nng lin quan n qun l ti nguyn v tuyn.

Giao din v tuyn s dng trong E-UTRAN by gi ch cn l S1 v X2.

Trong S1 l giao din v tuyn kt ni gia eNodeB v mng li. S1 chia lm

hai loi l S1-U l giao din gia eNodeB v SAE GW v S1-MME l giao din

gia eNodeB v MME. X2 l giao din gia cc eNodeB vi nhau.

Hnh 2-2: Cu trc c bn ca LTE

Mng li: mng li mi l s m rng hon ton ca mng li trong h thng

3G, v n ch bao ph min chuyn mch gi. V vy, n c mt ci tn mi:

Evolved Packet Core (EPC).

15


Cng mt mc ch nh E-UTRAN, s node trong EPC c gim. EPC

chia lung d liu ngi dng thnh mt phng ngi dng v mt phng iu

khin. Mt node c th c nh ngha cho mi mt phng, cng vi Gateway

chung kt ni mng LTE vi internet v nhng h thng khc. EPC gm c mt vi

thc th chc nng.

MME (Mobility Management Entity): chu trch nhim x l nhng chc

nng mt bng iu khin, lin quan n qun l thu bao v qun l phin. Gateway dch v (Serving Gateway): l v tr kt ni ca giao tip d liu

gi vi E-UTRAN. N cn hot ng nh mt node nh tuyn n nhng

k thut 3GPP khc. P-Gateway (Packet Data Network): l im u cui cho nhng phin

hng v mng d liu gi bn ngoi. N cng l Router n mng

Internet. PCRF (Policyand Charging Rules Function): iu khin vic to ra bng gi

v cu hnh h thng con a phng tin IP IMS (the IP Multimedia

Subsystem) cho mi ngi dng. HSS (Home Subscriber Server): l ni lu tr d liu ca thu bao cho tt

c d liu ca ngi dng. N l c s d liu ch trung tm trong trung

tm ca nh khai thc.

Cc min dch v bao gm IMS (IP Multimedia Sub-system) da trn cc nh

khai thc, IMS khng da trn cc nh khai thc v cc dch v khc. IMS l mt

kin trc mng nhm to s thun tin cho vic pht trin v phn phi cc dch v

a phng tin n ngi dng, bt k l h ang kt ni thng qua mng truy nhp

no. IMS h tr nhiu phng thc truy nhp nh GSM, UMTS, CDMA2000, truy

nhp hu tuyn bng rng nh cp xDSL, cp quang, cp truyn hnh, cng nh

truy nhp v tuyn bng rng WLAN, WiMAX. IMS to iu kin cho cc h

thng mng khc nhau c th tng thch vi nhau. IMS ha hn mang li nhiu li

ch cho c ngi dng ln nh cung cp dch v.

N v ang c tp trung nghin cu cng nh thu ht c s quan tm

ln ca gii cng nghip. Tuy nhin IMS cng gp phi nhng kh khn nht nh

16


v cng cha tht s chn thuyt phc cc nh cung cp mng u t trin

khai n. Kin trc IMS c cho l kh phc tp vi nhiu thc th v v s cc

chc nng khc nhau. IMS da trn cc nh khai thc: l IMS c tch hp sn

trong cu trc ca h thng 3GPP.

IMS khng da trn cc nh khai thc: l IMS khng c nh ngha trong

cc chun. Cc nh khai thc c th tch hp dch v ny trong mng ca

h. Cc UE kt ni n n qua vi giao thc c chp thun v dch v

video streaming l 1 v d. Cc dch khc khng c cung cp bi 3GPP v cu trc ph thuc vo

yu cu ca dch v. Cu hnh in hnh s c UE kt ni n my ch

qua mng chng hn nh kt ni n trang ch cho dch v lt web.

2.2.2 Cu trc ca LTE lin kt vi cc mng khc

Hnh 2-3: Cu trc h thng cho mng truy cp 3GPP

17


Hnh 2-4: Cu trc h thng cho mng truy cp 3GPP v khng phi 3GPP

Hnh 2-5: Cu trc h thng cho mng truy cp3GPP v lin mng vi CDMA2000

18


H thng 3GPP hin ti (GSM v WCDMA/HSPA) v 3GPP2 (CDMA2000

1xRTT, EV-DO) c kt hp vo h thng mi thng qua nhng giao din chun

ha, min l ti u tnh di ng vi LTE. Vi h thng 3GPP, iu ny c ngha l

mt giao din bo hiu gia SGSN (Serving GPRS Support Node) v mng li mi,

vi h thng 3GPP2 cng c mt giao din bo hiu gia CDMA RAN v mng li

mi.

V d tn hiu iu khin cho di ng c x l bi node Mobility

Management Entity (MME), tch ri vi Gateway. iu ny thun tin cho vic ti

u trong trin khai mng v hon ton cho php chia t l dung lng mt cch linh

ng. Home Subscriber Server (HSS) ni n Packet Core qua mt giao din IP, v

khng phi SS7 nh s dng trong mng GSM v WCDMA. Mng bo hiu cho

iu khin chnh sch v tnh cc c da trn giao din IP. H thng GSM v

WCDMA/HSPA hin ti c tch hp vo h thng mi qua nhng giao din c

chun ha gia SGSN v mng li mi. Ngi ta c gng kt hp truy nhp

CDMA cng s a n tnh di ng lin tc gia LTE v CDMA, cho php s

mm do trong vic chuyn ln LTE.

LTE-SAE tip nhn khi nim QoS theo tng lp. iu ny cung cp mt

gii php n gin v n by gi vn hiu qu cho nhng nh khai thc c c s

phn bit gia nhng dch v gi.

2.3 Cc knh s dng trong E-UTRAN

2.3.1 Knh vt l

Cc knh vt l s dng cho d liu ngi dng bao gm:

PDSCH (Physical Downlink Shared Channel) : ph ti c ch (payload) PUSCH (Physical Uplink Shared Channel) : PUSCH c dng mang d

liu ngi dng. Cc ti nguyn cho PUSCH c ch nh trn mt

subframe c bn bi vic lp biu ng ln. Cc sng mang c ch nhl 12 khi ti nguyn (RB) v c th nhy t subframe ny n subframe

khc. PUSCH c th dng cc kiu iu ch QPSK, 16QAM, 64QAM. PUCCH(Physical Uplink Control Channel): c chc nng lp biu,

ACK/NAK.

19


PDCCH(Physical Downlink Control Channel): lp biu, ACK/NAK. PBCH(Physical Broadcast Channel): mang cc thng tin c trng ca cell.

2.3.2 Knh logic

c nh ngha bi thng tin n mang bao gm:

Knh iu khin qung b (BCCH) : c s dng truyn thng tin iu

khin h thng t mng n tt c my di ng trong cell. Trc khi truy

nhp h thng, u cui di ng phi c thng tin pht trn BCCH bitc h thng c lp cu hnh nh th no, chng hn bng thng h

thng. Knh iu khin tm gi (PCCH) : c s dng tm gi cc u cui di

ng v mng khng th bit c v tr ca chng cp v v th cnpht cc bn tin tm gi trong nhiu (vng nh v).

Knh iu khin ring (DCCH) : c s dng truyn thng tin iu

khin ti/t mt u cui di ng. Knh ny c s dng cho cu hnh

ring ca cc u cui di ng chng hn cc bn tin chuyn giao khc nhau. Knh iu khin a phng (MCCH) : c s dng truyn thng tin cn

thit thu knh MTCH. Knh lu lng ring (DTCH): c s dng truyn s liu ca ngi s

dng n/t mt u cui di ng. y l kiu logic c s dng truyntt c s liu ng ln ca ngi dng v s liu ng xung ca ngidng khng phi MBMS.

Knh lu lng a phng (MTCH): c s dng pht cc dch v

MBMS.

2.3.3 Knh truyn ti

Knh qung b (BCH): c khun dng truyn ti c nh do chun cung cp. N c s dng pht thng tin trn knh logic. Knh tm gi (PCH): c s dng pht thng tin tm gi trn knh

PCCH, PCH h tr thu khng lin tc (DRX) cho php u cui tit kimcng sut c quy bng cch ng v ch thc thu PCH ti cc thi im quynh trc.

Knh chia s ng xung (DL-SCH) : l knh truyn ti pht s liu

ng xung trong LTE. N h tr cc chc nng ca LTE nh thch ngtc ng v lp biu ph thuc knh trong min thi gian v min tn s.N cng h tr DRX gim tiu th cng sut ca u cui di ng m vnm bo cm gic lun kt ni ging nh c ch CPC trong HSPA. DL-DCH

20


TTI l 1ms. Knh a phng (MCH) : c s dng h tr MBMS. N c c

trng bi khun dng truyn ti bn tnh v lp biu bn tnh. Trong trnghp pht a s dng MBSFN, lp biu v lp cu hnh khun dng truynti c iu phi gia cc tham gia pht MBSFN.

2.4 Giao thc ca LTE (LTE Protocols)

LTE chc nng ca RLC c chuyn vo eNodeB, cng nh chc

nng ca PDCP vi m ha v chn tiu . V vy, cc giao thc lin quan ca lp

v tuyn c chia trc y UTRAN l gia NodeB v RNC by gi chuyn

thnh gia UE v eNodeB.

Hnh 2-6: Giao thc ca UTRAN

21


Hnh 2-7: Giao thc ca E-UTRANGiao thc ca E-UTRAN pht trin thm ca UTRAN bng cch thm L1 v

MAC mi.

Hnh 2-8: Phn phi chc nng ca cc lp MAC, RLC, PDCPChc nng ca MAC (Medium Access Control) bao gm:

Lp biu

22


iu khin u tin (Priority handling) Ghp nhiu knh logic khc nhau trn mt knh truyn n RLC, cng nh

trong WCDMA c chc nng sau:- Truyn li trong trng hp giao nhn cc lp thp (MAC v L1) b

hng, tng t trong trng hp ch ACK ca RLC UTRAN- Phn on ph hp cho cc giao thc n v d liu- Cung cp cc knh vt l cho cc lp cao hn

Chc nng ca PDCP bao gm:

M ha (ciphering). Chn tiu .

Trong sut nm 2006, PDCP vn c gi s trong mng li, nhng quyt

nh hin ti l a PDCP vo eNodeB bao gm m ha. iu ny lm cho chc

nng v tuyn ca LTE tng t nh ca HPSA ci tin.

Trong giao din iu khin, chc nng ca giao thc RRC th cng ging

nh bn UTRAN. Giao thc RRC cu hnh cc thng s kt ni, iu khin bo co

o lng thit b u cui, cc lnh chuyn giaoM ASN1 c s dng cho

RRC ca LTE, n dn cch s khc bit gia cc phin bn ng tng thch

li.

Giao thc RRC s bao gm t trng thi hn EUTRAN. Ch c trng thi

tch cchay ri c d on bi v c tnh linh ng ca s phn b ngun

ti nguyn.

Cc trng thi ca RRC trong LTE l:

RRC-ri: thit b s quan st bn tin paging v s dng cell cho di ng.

Khng c RRC no lu tr trong bt k eNodeB c nhn no. UE ch c duy

nht mt ID nhn dng n trong vng di chuyn. RRC-kt ni: bit v tr ca UE cell no v d liu c pht v nhn.

Kt ni RRC tn ti n mt eNodeB. iu khin chuyn giao bi mng

c s dng cho di ng.

2.5 Mt s c tnh ca knh truyn

Ta tm hiu mt s c tnh ca knh truyn nh hng n vic truyn tn

hiu, cc c tnh ny bao gm tri tr, fading, dch tn Doppler, nh hng ca

23


dch tn Doppler i vi tn hiu OFDM, nhiu MAI, v cch khc phc nhiu

MAI.

2.5.1 Tri tr a ng

Tn hiu nhn c ni thu gm tn hiu thu trc tip v cc thnh phn phn

x. Tn hiu phn x n sau tn hiu thu trc tip v n phi truyn qua mt khong

di hn, v nh vy n s lm nng lng thu c tri rng theo thi gian. Khong

tri tr (delay spread) c nh ngha l khong chnh lch thi gian gia tn hiu

thu trc tip v tn hiu phn x thu c cui cng. Trong thng tin v tuyn, tri

tr c th gy nn nhiu xuyn k t nu nh h thng khng c cch khc phc.

i vi LTE, s dng k thut OFDM trnh c nhiu xuyn k t ISI.

2.5.2 Cc loi fading

Fading l s bin i cng tn hiu sng mang cao tn ti anten thu do

c s thay i khng ng u v ch s khc x ca kh quyn, cc phn x ca t

v nc trn ng truyn sng v tuyn i qua.

a) Rayleigh fading

Fadinh Rayleigh l loi Fading sinh ra do hin tng a ng (Multipath

Signal) v xc sut mc tn hiu thu b suy gim so vi mc tn hiu pht i tun

theo phn b Rayleigh.

b) Fading chn lc tn s v fading phng

Bng thng kt hp: l mt php o thng k ca di tn s m knh xem nh

l phng. Nu tri tr thi gian a ng l D(s) th bng thng kt hp Wc(Hz) xp

x bng: Wc 1/ 2piD

Trong fading phng, bng thng kt hp ca knh ln hn bng thng ca tn

hiu. V vy, s lm thay i u tn hiu sng mang trong mt di tn s. Trong fading chn lc tn s, bng thng kt hp ca knh nh hn bng

thng ca tn hiu. V vy, s lm thay i tn hiu sng mang vi mc thay i

ph thuc tn s.

24


2.6 Cc k thut s dng trong LTE

LTE s dng k thut OFDMA cho truy cp ng xung v SC-FDMA cho

truy cp ng ln. Kt hp ng thi vi MIMO, cc k thut v lp biu,

thchng ng truyn v yu cu t ng pht li lai ghp.

2.6.1 K thut truy cp phn chia theo tn s trc giao OFDM

Hnh 2-9: Nguyn l ca FDMA

Hnh 2-10: Nguyn l ca FDMA

Hnh 2-11: Nguyn l a sng mang

K thut iu ch OFDM, v c bn, l mt trng hp c bit ca phng

php iu ch FDM, chia lung d liu thnh nhiu ng truyn bng hp trong

vng tn s s dng, trong cc sng mang con (hay sng mang ph, sub-carrier)

trc giao vi nhau. Do vy, ph tn hiu ca cc sng mang ph ny c php

chng ln ln nhau m pha u thu vn khi phc li c tn hiu ban u. S

25


chng ln ph tn hiu ny lm cho h thng OFDM c hiu sut s dng ph ln

hn nhiu so vi cc k thut iu ch thng thng.

Hnh 2-12: So snh ph tn ca OFDM vi FDMA

Hnh 2-13: Tn s-thi gian ca tn hiu OFDMLTE s dng OFDM trong k thut truy cp ng xung v n c cc u

im sau:

OFDM c th loi b hin tng nhiu xuyn k hiu ISI (Inter-SymbolInterference) nu di chui bo v (guard interval) ln hn tr truyn dn lnnht ca knh truyn.

Thc hin vic chuyn i chui d liu t ni tip sang song song nn thigian symbol tng ln do s phn tn theo thi gian gy bi tri tr do truyn dna ng gim xung.

Ti u hiu qu ph tn do cho php chng ph gia cc sng mang con.

26


Hn ch c nh hng ca fading bng cch chia knh fading chn lc tn sthnh cc knh con phng tng ng vi cc tn s sng mang OFDM khc nhau.

OFDM ph hp cho vic thit k h thng truyn dn bng rng (h thng ctc truyn dn cao), nh hng ca s phn tp v tn s (frequency selectivity)i vi cht lng h thng c gim thiu nhiu so vi h thng truyn dn nsng mang.

Cu trc my thu n gin.Thch ng ng truyn v lp biu trong min tn s.Tng thch vi cc b thu v cc anten tin tin.

Hnh 2-14: Cc song mang giao vi nhauMt vn gp phi OFDM trong cc h thng thng tin di ng l cn

dch cc tn s tham kho i vi cc u cui pht ng thi. Dch tn ph hng

tnh trc giao ca cc cuc truyn dn n nhiu a truy nhp. V vy n rt nhy

cm vi dch tn. LTE chn khong cch gia cc sng mang l 15KHz, i vi

khong cch ny l khong cch ln i vi dch tn Doppler.

iu ch tn hiu OFDM s dng bin i FFT v IFFT cho bin i gia

min thi gian v min tn s.

27


Hnh 2-15: Bin i FFTChiu di bin i FFT l 2n vi n l s nguyn. Vi LTE chiu di c th l

512 hoc 1024...Ta s dng bin i IFFT khi pht i, ngun d liu sau khi iu

ch c chuyn i t ni tip sang song song. Sau c a n b bin i

IFFT. Mi ng vo ca IFFT tng ng vi tng sng mang con ring bit (thnh

phn tn s ring bit ca tn hiu min thi gian) v mi sng mang c iu ch

c lp vi cc sng mang khc. Sau khi c bin i IFFT xong, tn hiu c

chn thm tin t vng (CP) v pht i. b thu ta lm ngc li.

Hnh 2-16: Thu pht OFDM

28


Mc ch ca vic chn thm tin t vng l c kh nng lm gim hay loi

tr nhiu xuyn k hiu ISI (Inter Symbol Interference). Mt mu tn hiu c di

l TS, chui bo v tng ng l mt chui tn hiu c di TG pha sau c

sao chp ln phn pha trc ca mu tn hiu nh hnh v sau:

Hnh 2-17: Chui bo v GIDo , GI cn c gi l Cyclic Prefix (CP). S sao chp ny c tc dng chng

li nhiu xuyn k hiu ISI do hiu ng phn tp a ng.

Nguyn tc ny gii thch nh sau: Gi s my pht i mt khong tn hiu c chiu

di l Ts, sau khi chn thm chui bo v c chiu di TG th tn hiu ny c chiu

di l T = TS+TG. Do hiu ng a ng multipath, tn hiu ny s ti my thu

theo nhiu ng khc nhau. Trong hnh v, hnh a, tn hiu theo ng th nht

khng c tr, cc ng th hai v th ba u b tr mt khong thi gian so vi

ng th nht. Tn hiu thu c my thu s l tng hp ca tt c cc tuyn,

cho thy k hiu ng trc s chng ln vo k hiu ngay sau , y chnh l hin

tng ISI.Do trong OFDM c s dng chui bo v c di TG s d dng loi b

hin tng ny. Trong trng hp TG MAX nh hnh v m t th phn b chng

ln ISI nm trong khong ca chui bo v, cn thnh phn tn hiu c ch vn an

ton. pha my thu s loi b chui bo v trc khi gi tn hiu n b gii iu

ch OFDM. Do , iu kin cn thit cho h thng OFDM khng b nh hng

bi ISI l: TG MAX vi MAX l tr truyn dn ti a ca knh

29


a ) Khng c GI

b) C GI

Hnh 2-18: Tc dng ca chui bo vOFDM lng t ha trong min tn s da trn c lng p ng tn s

ca knh. Do n hot ng n gin hn WCDMA v n khng ph thuc vo

chiu di ca knh (chiu di ca a ng trong cc chip) nh khi lng t

WCDMA. Trong WCDMA cc cell khc nhau c phn bit bi cc m tri ph

khc nhau nhng trong OFDM tri ph khng c gi tr, n s dng cc k hiu

tham kho ring bit gia cc cell hoc gia cc anten khc nhau.

LTE s dng OFDMA (Orthogonal Frequency Division Multiple Access)

cho tuyn ln. OFDMA gi l a truy nhp phn chia theo tn s trc giao l cng

ngh a truy cp phn chia theo sng mang, l mt dng nng cao, l phin bn a

ngi dng ca m hnh iu ch s OFDM

K thut a truy nhp ca 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. iu ny cho php truyn

30


d liu tc thp t nhiu ngi s dng.

Hnh 2-19: Sng mang con OFDMA

Hnh 2-20: OFDM v OFDMATi nguyn thi gian - tn s c chia nh theo cu trc sau : 1 radio frame

c chiu di l 10ms, trong chia thnh nhiu subframe nh c chiu di l 1ms,

v mi subframe nh li c chia thnh 2 slot vi chiu di ca mi slot l 0.5ms.

Mi slot s bao gm 7 k t OFDM trong trng hp chiu di CP thng

thng v 6 k t OFDM trong trng hp CP m rng.

Trong OFDMA, vic ch nh s sng mang con cho ngi dng khng da

vo tng sng mang con ring l m da vo cc khi ti nguyn (Resource Block).

Mi khi ti nguyn bao gm 12 sng mang con cho khong thi gian 1 slot v

khong cch gia cc sng mang con l 15KHz dn n kt qu bng thng ti

thiu ca n l 180 KHz. n v nh nht ca ti nguyn l thnh phn ti nguyn

(RE), n bao gm mt sng mang con i vi khong thi gian ca mt k t

OFDM. Mt RB bao gm 84 RE (tc 7 x12) trong trng hp chiu di CP thng

thng v 72 RE (6x12) trong trng hp chiu di CP m rng.

31


Hnh 2-21: Ch nh ti nguyn ca OFDMA trong LTEBng 2-4: S khi ti nguyn theo bng thng knh truyn

Bng thng knh truyn (MHz) 1.4 3 5 10 15 20S khi ti nguyn 6 15 25 50 75 100

Hnh 2-22: Cu trc ca mt khi ti nguynTn hiu tham kho (RS): LTE s dng cc tn hiu tham kho c bit d dng

c lng dch sng mang, c lng knh truyn, ng b thi gianCc tn hiu

tham kho c b tr nh hnh sau:

32


Hnh 2-23: Cu trc b tr tn hiu tham khoCc tn hiu tham kho ny c pht k t OFDM th nht v th nm

ca mi slot v sng mang th su ca mi subframe. Tn hiu tham kho cng

c s dng c lng tn hao ng truyn s dng cng sut thu tn hiu

tham kho (RSRP).

Nhc im ca OFDM l g? Ta xt cc hnh sau:

Hnh 2-24: c tnh ng bao ca tn hiu OFDM

33


Hnh 2-25: PAPR cho cc tn hiu khc nhauT cc hnh trn ta thy, dng sng OFDM th hin s thng ging ng

bao rt ln dn n PAPR cao. Tn hiu vi PAPR cao i hi cc b khuch i

cng sut c tnh tuyn tnh cao trnh lm mo dng tn hiu. t c mc

tuyn tnh ny, b khuch i phi lm vic ch cng tc vi li (so vi

im bo ha cao). iu ny dn n hiu sut s dng cng sut (t s cng sut

pht vi cng sut tiu th mt chiu) thp v th c bit nh hng i vi cc

thit b cm tay. khc phc nhc im ny, 3GPP nghin cu s dng

phng php a truy nhp ng ln s dng DTF S-OFDM vi tn gi l SC-

FDMA v p dng cho LTE.

2.6.2 K thut SC-FDMA

Cc tn hiu SC-FDMA (Single Carrier Frequency Division Multiple Access)

c tn hiu PAPR tt hn OFDMA. y l mt trong nhng l do chnh chn

SC-FDMA cho LTE. PAPR(Peak-to-Average Power Ratio) gip mang li hiu qu

cao trong vic thit cc b khuch i cng sut UE, v vic x l tn hiu ca SC-

FDMA vn c mt s im tng ng vi OFDMA, do , tham s hng DL v

34


UL c th cn i vi nhau. Tn hiu SC-FDMA c to ra bng k thut tri ph

DFT-OFDM (DFT-s-OFDM)

Hnh 2-26: S khi DFT-s-OFDME-UTRA hng UL cng s dng cc k thut iu ch QPSK, 16QAM v

64 QAM. Vi DFT-s-OFDM, vic bin i Fourier ri rc (DFT - Discrete Fourier

Transform) kch thc M-Point FFT c p dng u tin trong khi cc k hiu

iu ch. DFT chuyn i cc k hiu iu ch thnh min tn s. Kt qu s c

nh x vo cc sng mang th cp c sn. Hng UL ch cho php nh v truyn

dn trn cc Sub-carrier lin tc. Trc khi c chuyn i t song song sang ni

tip, N-point IFFT c thm vo mt chu k.Do , vic x l DFT c s khc bit c bn gia tn hiu SC-FDMA v

OFDMA. iu ny sinh ra thut ng "DFTspread-OFDM". Trong tn hiu SC-

FDMA, mi Sub-carrier s dng truyn ti thng tin c cha tt c cc k hiu

iu ch, do , chui d liu u vo phi c tri ph bng bin i DFT trn

cc Sub-carrier c sn. Ngc li, mi Sub-carrier ca tn hiu OFDMA ch mang

thng tin c lin quan n cc k hiu iu ch c th.

2.6.3 K thut a anten MIMO

Trung tm ca LTE l tng ca k thut a anten, c s dng e tng

vng ph sng v kh nng ca lp vt l. Thm vo nhiu anten hn vi mt h

thng v tuyn cho php kh nng ci thin hiu sut bi v cc tn hiu pht ra s

35


c cc ng dn vt l khc nhau. C ba loi chnh ca k thut a anten. u tin

n gip s dng trc tip s phn tp ng dn trong mt s bc x ng dn

c th b mt mt do fading v mt ci khc c th khng. Th hai l vic s dng

k thut hng bp sng(beamforming) bng cch iu khin mi tng quan pha

ca cc tn hiu in pht ra vo cc anten vi nng lng truyn li theo t nhin.

Loi th ba s dng s phn tch khng gian ( s khc bit ng dn bng cch

tch bit cc anten ) thng qua vic s dng ghp knh theo khng gian v s to

chm tia, cn c gi l k thut a u vo, a u ra (MIMO ).

Hnh 2.27 cho thy, c 4 cch thc hin vic s dng knh v tuyn. e

n gin cc v d c miu t ch s dng mt hoc hai anten.

Hnh 2-27: Cc ch truy nhp knh v tuynBao gm :

n u vo n u ra (SISO)n u vo a u ra (SIMO)a u vo n u ra (MISO)a u vo a u ra (MIMO)

LTE s dng k thut a anten MIMO, ta tp trung tm hiu v k thut ny.

T hnh 2.27, ta c th thy MIMO yu cu 2 hoc nhiu my pht v hai hoc

nhiu my thu. MIMO lm tng cng sut ph bng cch pht nhiu lung d liu

cng mt lc trong cng mt tn s v thi gian, tn dng y cc li th ca cc

36


ng dn khc nhau trong knh v tuyn. i vi mt h thng c m t nh

MIMO, n phi c t nht l nhiu my thu vi nhiu lung pht, s lng cc

lung pht khng c nhm ln vi s lng cc ng ten pht. Hy xem xt trng

hp phn tp pht (MISO) trong c hai my pht nhng ch c mt dng d liu.

Thm na s phn tp thu (SIMO) khng chuyn cu hnh ny vo MIMO, mc d

hin ti c hai anten pht v hai anten thu c lin quan. Ni cch khc

SIMO+MISO # MIMO. Nu N lung d liu c truyn t t hn N anten, d liu

c th khng c gii xo trn mt cch y bi bt k my thu no t to

ra s chng cho cc lung m khng c s b sung ca phn tp theo khng gian

th ch to ra nhiu. Tuy nhin v mt khng gian vic tch bit N cc lung qua ti

thiu N anten, N my thu s c th ti to li y d liu ban u v nhiu trong

knh v tuyn l thp. Mt yu t quan trng cho hot ng MIMO l vic

truyn t mi anten phi l duy nht mi my thu c th xc nh c ci g m

n nhn c. Vic nhn dng ny thng c thc hin vi cc tn hiu ch

o, trong s dng cc mu trc giao cho mi anten. S phn tp khng gian ca

knh v tuyn ngha l MTMO c kh nng lm tng tc d liu. Hnh thc c

bn nht ca MIMO l gn mt dng d liu cho mi anen v c th hin nhu

trong hnh 2.28

Hnh 2-28: MIMO 2x2 khng c tin m haTrong dng ny, mt lung d liu duy nht c gn cho mt anten v c

bit n nh nh x trc tip. Sau chng c trn ln vi nhau trn knh, mi

anten thu s nhn mt s kt hp ca cc lung. Bn thu s s dng mt b lc

nghch o v tng hp cc lung nhn c ri ti to li d liu gc. Mt dng

tin tin hn ca MIMO l tin m ha c bit ph hp vi vic truyn dn

ch c bit ca knh. Kt qu ny ti u trong mi lung c lan truyn qua

37


nhiu hn mt anten pht. Vi k thut ny lm vic hiu qu my pht phi c

s hiu bit v cc iu kin knh truyn, v trong trng hp FDD cc iu kin

ny phi c cung cp trong thi gian thc bi thng tin phn hi t UE. Nh vy

n s lm phc tp thm mt cch ng k cho vic ti u ha nhng h thng c

th lm vic vi hiu sut cao hon. Tin m ha vi h thng TDD khng yu cu

nhn phn hi bi v my pht s xc nh mt cch c lp cc iu kin ca knh

truyn bi vic phn tch cc tn hiu nhn c trn cng mt tn s.

Nhng li ch v mt l thuyt ca MIMO l chc nng ca s lng cc

anten truyn v nhn, cc iu kin lan truyn v tuyn, SNR v kh nng ca my

pht thch nghi vi cc iu kin thay i. Trng hp l tng l mt trong cc

ng dn trong knh truyn v tuyn l hon ton khng tng quan, nh th

ring bit, cc kt ni cp vt l khng c xuyn m gia my pht v my thu.

iu kin nh vy gn nh l khng t c Irong khng gian t do. Cc gii hn

trn ca MIMO t c trong cc iu kin l tng l dc dng xc nh, v cho

mt h thong 2x2 vi hai lung d liu ng thi lm tng gp i cng sut v tc

d liu l c th. MIMO hot ng tt nht trong cc iu kin SNR cao vi

ng tm nhn cc tiu. Kt qu l, MIMO c bit ph hp vi mi trng trong

nh, c th to ra mt mc cao ca a ng v tm nhn cc tiu.

2.6.4 M ha Turbo

sa nhng bit b li do s thay i knh v nhiu, m ha knh c s

dng. Vi knh chia s hng xung ca LTE (DL-SCH), s dng mt b m ha

Turbo vi tc 1/3, theo sau l mt b so khp tc thch ng vi tc m.

Trong mi khung con chiu di 1ms, mt hoc hai t m c th c m ha v

truyn i.

2.7 iu khin cng sut

WCDMA, ta s dng iu khin cng sut c ng ln v ng xung.

Nhng i vi LTE, ch cn s dng iu khin cng sut ng ln. iu khin

cng sut ng ln trong h thng thng tin di ng vi cc mc ch quan trng

sau: n cn bng cng sut pht i vi QoS yu cu, ti thiu can nhiu v tng

38


tui th pin ca thit b u cui. t c cc mc ch ny, iu khin cng sut ng ln phi thch

nghi vi cc c tnh ca knh truyn v tuyn, bao gm tn hao, che bng, fading

nhanh, cng nh can nhiu n t cc user khc - trong vng mt cell hay cc

cell ln cn.i hi cho vic qun l can nhiu ng ln LTE kh l khc so vi

WCDMA. WCDMA, ng ln khng trc giao v vic qun l can nhiu u

tin l can nhiu gia cc user khc nhau trong cng mt cell. Cc user ng ln

WCDMA chia s cng ti nguyn v thi gian - tn s v chng to ra can nhiu

tng trn nhiu nhit ti b thu ca NodeB. iu ny c bit nh Rise over

Thermal (RoT), v n phi c iu khin cn thn v c chia s gia cc user.Tng tc d liu ng ln cho user WCDMA th gim c h s

tri ph v tng cng sut pht tng ng.Nhng ngc li, hng ln LTE th da trn trc giao, vic qun l can

nhiu gia cc user trong cng mt cell th t quan trng hn WCDMA. Thay i

tc d liu ng ln LTE th bng thng pht thay i v thay i MCS,

trong khi cng sut pht trn n v bng thng (chng hn nh PSD) c th khng

i i vi mt MCS.Hn na, WCDMA iu khin cng sut c thit k vi truyn dn lin

tc cho cc dch v chuyn mch knh, trong khi LTE, lp biu nhanh cho cc UE

c p dng ti khong thi gian 1ms. iu ny c phn nh trong thc t l

iu khin cng sut WCDMA c d on vi vng lp tr hon l 0,67 ms v

bc iu khin cng sut thng thng l +/- 1 dB. Trong khi LTE cho php

bc iu khin cng sut rng hn (khng phi d on), vi vng lp tr hon

khong 5 ms. K thut iu khin cng sut LTE kt ni c vng h v vng kn.

Hi tip vng kn ch cn thit b cho trng hp UE c lng cng sut pht

khng tha mn.

2.7.1 iu khin cng sut vng h

iu khin cng sut vng h c lng tn hao t c sau khi o lng

RSRP v tnh ton cng sut pht da trn phng trnh sau:PPUSCH = min {Pmax , 10log10M + P0 + .PL}

39


Hnh 2-29: iu khin cng sut vng h

2.7.2 iu khin cng sut vng kn

UE s iu chnh cng sut pht ca mnh da trn lnh TCP. Lnh TCP

c pht da bi eNodeB n UE, da trn SINR mong mun v SINR m

eNodeB thu c. Trong h thng iu khin cng sut vng kn , b thu ng ln

ti eNodeB c lng SINR ca tn hiu thu v n so snh vi gi tr SINR mong

mun. Khi SINR thu c thp hn SINR mong mun, lnh TCP c pht n UE

yu cu tng cng sut pht. Ngc li, lnh TCP s yu cu UE gim cng sut

pht.

Thch ng nhanh c p dng quanh im hot ng vng h to thnh

iu khin cng sut vng kn. iu ny c th iu khin can nhiu v tinh chnh

cng sut ph hp vi iu kin knh truyn (bao gm fading nhanh). Tuy nhin,

do tnh trc giao ng ln ca LTE, iu khin cng sut vng kn ca LTE

khng cn s dng iu khin cng sut vng kn nhanh nh p dng i vi

WCDMA ( trnh vn gn xa). Thay i bng thng pht cng vi vic thit

40


lp MSC t c n tc d liu pht mong mun.

Hnh 2-30: iu khin cng sut vng knDelta- MCS: cho php cng sut trn khi ti nguyn thch nghi theo tc

pht d liu thng tin. Cng sut pht i hi trn khi ti nguyn l (2k.BPRE 1).

Trong BPRE l t s s bit thng tin trn thnh phn ti nguyn RE trong mt

RB, k l h s t l v gi tr thch hp cho k l 1.25 i vi cng sut offset ph

thuc vo MCS.

2.8 Chuyn giao.

Cc mng di ng cho php ngi s dng c th truy nhp cc dch v trong

khi di chuyn nn c thut ng t do cho cc thit b u cui. Tuy nhin tnh t

do ny gy ra mt s khng xc nh i vi cc h thng di ng. S di ng ca

cc ngi s dng u cui gy ra mt s bin i ng c trong cht lng lin kt

41


v mc nhiu, ngi s dng i khi cn yu cu thay i trm gc phc v. Qu

trnh ny c gi l chuyn giao .

Chuyn giao l mt phn cn thit cho vic x l s di ng ca ngi s

dng u cui. N m bo tnh lin tc ca cc dch v v tuyn khi ngi s

dng di ng di chuyn t qua ranh gii cc t bo.

Trong cc h thng t bo th h th nht nh AMPS, vic chuyn giao tng

i n gin. Sang h thng thng tin di ng th h 2 nh GSM v PACS th c

nhiu cch c bit hn bao gm cc thut ton chuyn giao c kt hp cht ch

trong cc h thng ny v tr chuyn giao tip tc c gim i. Khi a ra cng

ngh CDMA, mt tng khc c ngh ci thin qu trnh chuyn giao

c gi l chuyn giao mm. Vi h thng 3G v 4G th qu trnh chuyn giao tr

ln kh phc tp, bao gm chuyn giao gia cc trm BTS trong cng mt mng,

chuyn giao gia cc cng ngh mng, chuyn giao gia cc tn s. Chuyn giao c

th thc hin bi nh mng, thit b u cui, ngi s dng.

2.8.1 Mc ch chuyn giao

L do c bn ca vic chuyn giao l kt ni v tuyn khng tha mn mt b

tiu chun nht nh v do hoc UE hoc E-UTRAN s thc hin cc cng vic

ci thin kt ni . Khi thc hin cc kt ni chuyn mch gi, chuyn giao

c thc hin khi c UE v mng u thc hin truyn gi khng thnh cng. Cc

iu kin chuyn giao thng gp l: iu kin cht lng tn hiu, tnh cht di

chuyn ca thu bao, s phn b lu lng, bng tn

iu kin cht lng tn hiu l iu kin khi cht lng hay cng tn

hiu v tuyn b suy gim di mt ngng nht nh. Chuyn giao ph thuc vo

cht lng tn hiu c thc hin cho c hng ln ln hng xung ca ng

truyn dn v tuyn.

Chuyn giao do nguyn nhn lu lng xy ra khi lu lng ca cell t ti

mt gii hn ti a cho php hoc vt qu ngng gii hn . Khi cc thu

42


bao ngoi ra ca cell (c mt ti cao) s c chuyn giao sang cell bn cnh

(c mt ti thp).

S lng chuyn giao ph thuc vo tc di chuyn ca thu bao. Khi UE di

chuyn theo mt hng nht nh khng thay i, tc di chuyn ca UE cng

cao th cng c nhiu chuyn giao thc hin trong E-UTRAN.

2.8.2 Cc loi chuyn giao (HO-handover)

Ty theo hnh thc s dng trong cc c ch chuyn giao, c th phn chia

chuyn giao thnh cc nhm nh: chuyn giao cng, chuyn giao mm v chuyn

giao mm hn.

a) Chuyn giao bn trong h thng (Intra-system HO)Chuyn giao bn trong h thng xut hin trong phm vi mt h thng. N

c th chia thnh chuyn giao bn trong tn s(Intra-frequency HO) v chuyn

giao gia cc tn s(Inter-frequency HO). Chuyn giao trong tn s xut hin

gia cc cell thuc cng mt sng mang WCDMA, cn chuyn giao gia cc tn

s xut hin gia cc cell hot ng trn cc sng mang WCDMA khc nhau.b) Chuyn giao gia cc h thng(Inter system HO)

Kiu chuyn gia ny xut hin gia cc cell thuc v 2 cng ngh truy

nhp v tuyn khc nhau (RAT) hay cc ch truy nhp v tuyn khc nhau

(RAM). Trng hp ph bin nht cho kiu u tin dng chuyn giao gia

cc h thng WCDMA v GSMEDGE. Chuyn giao gia 2 h thng CDMA

cng thuc kiu ny.

a) Chuyn giao cng(HHO Hard Handover )HHO l mt loi th tc chuyn giao trong tt c cc lin kt v tuyn

c ca mt my di ng c gii phng trc khi lin kt vi v tuyn mi

c thit lp. i vi cc dch v thi gian thc, th iu c ngha l c mt

s gin on ngn xy ra, cn vi dch v phi thi gian thc th HHO khng nh

hng g. Chuyn giao cng din ra nh l chuyn giao trong cng tn s v

chuyn giao ngoi tn s.b) Chuyn giao mm (SHO Soft Handover) v chuyn giao mm hn

(Softer HO)

43


Chuyn giao ch c trong cng ngh CDMA. So vi chuyn giao cng

thng thng, chuyn giao mm c `mt s u im. Tuy nhin, n cng c mt

s hn ch v s phc tp v vic tiu th ti nguyn tng ln. Vic quy hoch

chuyn giao mm ban du l mt trong cc phn c bn ca vic hoch nh v

ti u ha mng v tuyn.

c) Nguyn l chuyn giao mm:

Chuyn giao mm khc vi qu trnh chuyn giao cng truyn thng. i

vi chuyn giao cng, mt quyt nh xc nh l c thc hin chuyn giao hay

khng v my di ng ch giao tip vi mt BS ti mt thi im. i vi

chuyn giao mm, mt quyt nh c iu kin c to ra l c thc hin

chuyn giao hay khng. Ty thuc vo s thay i cng knh hoa tiu t hai

hay nhiu trm gc c lin quan, mt quyt nh cng cui cng s to ra giao

tip vi duy nht mt BS. iu ny thng din ra sau khi d liu n t mt BS

chc chn s mnh hn cc tn hiu n t BS khc. Trong thi k chuyn tip

ca chuyn giao mm, MS giao tip ng thi vi cc BS trong tp hp tch

cc(Tp hp tch cc l danh sch cc cell hin ang c kt ni vi MS).

Hnh 2-31: So snh chuyn giao cng v chuyn giao mm

44


Trong sut qu trnh chuyn giao mm, mt my di ng ng thi giao tip

vi c hai hoc nhiu cell(i vi c hai chuyn giao mm) thuc v trm gc khc

nhau ca cng mt iu khin mng v tuyn(intra RNC) hoc cc b iu khin

mng v tuyn khc nhau(inter RNC). Trn ng xung (DL), my di ng nhn

cc tn hiu kt hp vi t s ln nht. Trn ng ln (UL), knh m di ng

c tch bi c hai BS(i vi c hai kiu SHO), v c nh tuyn n b iu

khin v tuyn cho s kt hp la chn. Hai vng iu khin cng sut tch cc u

tham gia vo chuyn giao mm: mi vng cho mt BS. Trong trng hp chuyn

giao mm hn, mt my di ng c iu khin bi t nht hai sector trong cng

mt BS, RNC khng quan tm v ch c mt vng iu khin cng sut hot ng.

Chuyn giao mm v chyn giao mm hn ch c th xy ra trong cng mt tn s

sng mang, do chng l cc qua trnh chyn giao trong cng tn s.

d) Cc c im ca chuyn giao mm:So vi phng thc chuyn giao cng truyn thng, chuyn giao mm c

nhng u im r rng, nh loi tr hiu ng ping pong v to ra s lin tc

trong truyn dn(khng c ngt qung trong chuyn giao mm). Khng c hiu ng

ping pong c ngha l ti trong d liu mng thp hn v trong chuyn giao

mm, th khng c suy hao d liu do truyn dn d liu b ngt nh trong chuyn

giao cng.Tt c cc chuyn giao ni trn c th quy v hoc l chuyn giao cng cng

ngh: l chuyn giao gia cc mng c s dng cng cng ngh nh WLAN sang

WLAN hay UMTS sang UMTS hoc chuyn giao khc cng ngh l chuyn giao

gia cc mng c s dng cng ngh khc nhau nh WLAN sang UMTS v ngc

li v do trn cc thit b di ng phi c cc giao din khc nhau cho tng loi

cng ngh. Chuyn giao ngang l chuyn giao cng cng ngh, cn chuyn giao

dc c th l chuyn giao cng hay khc cng ngh. c th s dng trong thc t th mi qu trnh chuyn giao phi tha mn

cc yu cu sau:Chuyn giao lin tc: qu trnh chuyn giao phi xy ra m khng c tn

tht(gi d liu) hoc c rt t v phi c d liu thp.

45


S thay i v giao thc cng nh b sung thm cc thnh phn l chp nhn

c (da trn nn tng giao thc v thit b ph bin hin nay) v khng lm nh

hng n cc hot ng mng bnh thng khc.

2.8.3 Handover trong h thng thng tin di ng 4G

Mng 4G l mt mng c bit n vi nhiu cng ngh mng khc nhau,

bi vy ta c th khai qut qu trnh mt thit b di ng (in thoi di ng, my

tnh xch tay, hay pda ) ang kt ni vo mng m thay i im kt ni (t

mng ny sang mng khc) gi l qu trnh chuyn giao (handover hay handoff).

Trong mng thng tin di ng 4G c nhiu loi chuyn giao khc nhau, ch yu

chia lm hai loi sau y:

a) Chuyn giao ngang (horizontal handover)

L qu trnh chuyn giao ch nh hng n lp kt ni (lp hai) m khng

lm thay i a ch IP(nm lp ba). V d nh khi thit b di ng di chuyn gia

hai im truy cp (Access Point) ca mng LAN khng dy (WLAN) c qun l

bi cng mt Router.

Hnh 2-32: Chuyn giao ngangb) Chuyn giao dc (vertical handover)

Qu trnh chuyn giao lm nh hng n c lp kt ni v lp mng c

gi l chuyn giao dc. Qu trnh chuyn giao ny c th lm thay i a ch IP

ca thit b. V d: thit b di ng c th di chuyn gia cc im truy nhp thuc

46


quyn qun l ca cc Router truy nhp khc nhau; hay thit b di ng c th di

chuyn gia hai mng thuc v hai nh cung cp khc nhau; hay thit b di ng c

th di chuyn khi vng ph sng ca 1 mng WLAN v i vo vng ph sng ca

1 mng di ng: GPRS hoc UMTS m hai mng ny c qun l bi cc nh

cung cp khc nhau nh hnh v bn di.

Hnh 2-33: chuyn giao dc

2.8.4 Trnh t chuyn giao

Trnh t chuyn giao gm c ba pha : pha o lng, pha quyt nh v pha

thc hin.o lng l nhim v quan trng trong qu trnh chuyn giao v hai l do c

bn sau: Mc tn hiu trn ng truyn dn v tuyn thay i rt ln ty thuc vo fading

v tn hao ng truyn. Nhng thay i ny ph thuc vo mi trng trong cell

v tc di chuyn ca thu bao. S lng cc bo co o lng qu nhiu s lm nh hng n ti h thng.

thc hin chuyn giao, trong sut qu trnh kt ni, UE lin tc o cng

tn hiu ca cc cell ln cn v thng bo kt qu ti mng, ti eNodeB.

Pha quyt nh chuyn giao bao gm nh gi tng th v QoS ca kt ni so

snh n vi cc thuc tnh QoS yu cu v c lng t cc cell ln cn. Ty theo

kt qu so snh m ta c th quyt nh thc hin hay khng thc hin chuyn giao.

eNodeB kim tra cc gi tr ca cc bo co o c kch hot mt b cc iu

kin chuyn giao. Nu cc iu kin ny b kch hot, eNodeB phc v s cho php

47


thc hin chuyn giao.

Cn c vo quyt nh chuyn giao, c th phn chia chuyn giao ra thnh

hai loi nh sau:

Chuyn giao quyt nh bi mng (NEHO). Chuyn giao quyt nh bi thu bao di ng (MEHO).

Trong trng hp chuyn giao thc hin bi mng (NEHO), eNodeB thc

hin quyt nh chuyn giao. Trong trng hp MEHO, UE thc hin quyt nh

chuyn giao. Trong trng hp kt hp c hai loi chuyn giao NEHO v MEHO,

quyt nh chuyn giao c thc hin bi s phi hp gia eNodeB vi UE.Ngay c trong trng hp chuyn giao MEHO, quyt nh cui cng v vic thc

hin chuyn giao l do eNodeB. ENodeB c trch nhim qun l ti nguyn v

tuyn (RRM) ca ton b h thng.

Hnh 2-34: Nguyn tc chung ca cc thut ton chuyn giao

Quyt nh chuyn giao da trn cc thng tin o c ca UE v eNodeB cng

nh cc iu kin thc hin thut ton chuyn giao. Nguyn tc chung thc hin

thut ton chuyn giao c th hin trn hnh trn.

a) Cc thut ng v cc tham s sau c s dng trong thut ton chuyn

giao: Ngng gii hn trn: l mc tn hiu ca kt ni t gi tr cc i cho php tha

mn mt cht lng dch v QoS yu cu. Ngng gii hn di: l mc tn hiu ca kt ni t gi tr cc tiu cho php tha

mn mt cht lng dch v QoS yu cu. Do mc tn hiu ca ni kt khng

c nm di ngng .

48


Gii hn chuyn giao: l tham s c nh ngha trc c thit lp ti im m

cng tn hiu ca cell bn cnh (cell B) vt qu cng tn hiu ca cell

hin ti (cell A) mt lng nht nh. Tp tch cc: l mt danh sch cc nhnh tn hiu (cc cell) m UE thc hin kt

ni ng thi ti mng truy nhp v tuyn (E-UTRAN). Gi s thu bao UE trong

cell A ang chuyn ng v pha cell B, tn hiu hoa tiu ca cell A b suy gim n

mc ngng gii hn di. Khi t ti mc ny, xut hin cc bc chuyn giao

theo cc bc sau y:

(1) Cng tn hiu A bng vi mc ngng gii hn di. Cn tn hiu B s

c RNC nhp vo tp tch cc. Khi UE s thu tn hiu tng hp ca hai kt ni

ng thi n UTRAN.

(2) Ti v tr ny, cht lng tn hiu B tt hn tn hiu A nn n c coi l

im khi u khi tnh ton gii hn chuyn giao.

(3) Cng tn hiu B bng hoc tt hn ngng gii hn di. Tn hiu A b

xa khi tp tch cc bi RNC.

Kch c ca tp tch cc c th thay i c v thng thng trong khong

t 1 n 3 tn hiu.

49


2.8.5 Chuyn giao gia mng LTE v 3G

Hnh 2-35: Chuyn giao gia LTE v 3GQu trnh chun b chuyn giao c thc hin trc khi chuyn i h

thng, bao gm cc cng vic nh bo v cc ngun ti nguyn trn mng ch

thng qua qu trnh s l gia cc qu trnh truy nhp v tuyn. Khi chuyn giao

xy ra, gim thiu thi gian s l ch cc ng dn cn thit mi c chuyn

i, chc nng chuyn tip d liu c s dng trnh mt cc gi tin c

chuyn n trc thi im chuyn giao.b) Cc bc chun b thc hin chuyn giao t LTE sang 3G

50


Hnh 2-36: Cc th tc chun b chuyn giao t LTE sang 3GBc (1): Cc thit b u cui s gi mt bo co cht lng pht trm c

s v cc thng tin khc cho cc eNodeB. Da trn cc thng tin trn eNodeB s

gi quyt nh bn giao, xc nh cc trm c s v RNC chuyn sang, v bt

u chun b bn giao.Bc (2) (3) : eNodeB gi mt yu cu bn giao MME, ch ra RNC cho h

thng truy cp v tuyn ch. MME xc nh cc SGSN kt ni vi RNC ch v

gi kim sot truyn thng v cc thng tin khc nhn c t eNodeB vi SGSN

trong mt tn hiu yu cu chuyn tip v tr. Cc thng tin cn thit cu hnh cc

ng dn gia S-GW v SGSN, c s dng truyn d liu sau khi MME

hon tt qu trnh chuyn giao.Bc (4) (5): SGSN chuyn cc yu cu kt ni ca eNodeB n RNC. RNC

thc hin x l cu hnh sng radio da trn cc thng tin nhn v tr li SGSN. Bc (6): SGSN gi mt bn tin tr li chuyn tip v tr ti MME thng

bo rng th tc ti nh c hon thnh. Tn hiu ny cng bao gm cc d liu

do SSGN to ra, cu hnh kt ni gia S-GW v SGSN, c s dng chuyn

tip d liu.Bc (7) n (8) :MME gi mt yu cu thit lp ng hm chuyn d liu

gin tip vo S-GW, thng bo cc thng tin n va nhn c t SSGN. T cc

thng tin m S-GW nhn c, n thit lp ng thng tin lin lc t S-GW n

51


SGSN chuyn tip d liu v gi mt bn tin tr li n MME.Thng qua qu trnh chun b chuyn giao ny, ti nguyn v tuyn 3G

sn sng, sng mang truy nhp gia SGSN v RNC c cu hnh, v con ng

chuyn tip d liu t S-GW n SGSN c cu hnh xong.c) Cc th tc thc hin chuyn giao t LTE sang 3G

Hnh 2-37: Qu trnh chuyn giao t LTE v 3GBc (1) (2): Khi qu trnh chun b xy ra chuyn giao c hon thnh,

MME gi mt lnh chuyn giao cho eNodeB. Khi nhn c tn hiu ny, eNode s

gi mt lnh chuyn giao t LTE cho thit b u cui chuyn i cc h thng

v tuyn. Lu khi eNode nhn c lnh chuyn giao t MME, n bt u

chuyn tip gi d liu nhn c t S-GW. Sau , cc gi tin c i theo ng

dn: S-GW, eNodeB, S-GW, SGSN, RNCBc (3) (6): thit b u cui chuyn sang 3G v khi ng truyn c

hon thin cu hnh, mt thng bo kt ni vi 3G s c truynt thit b u

cui RNC , t RNC n SGSN v t SGSN MME. Bng cch ny, MME c th

thc hin Bc (10) m t di y gii phng ti nguyn eNodeB sau mt

khong thi gian nh trc.Bc (7): MME chuyn bn tin xc nhn hon thnh qu trnh chuyn tip

ti SGSN. Sau mt khong thi gian t khi nhn c tn hiu ny SGSN gii

phng cc ti nguyn lin quan n chuyn tip d liu.

52


Bc (8): SGSN gi mt yu cu sa i sng mang ti S-GW thay i

ng thng tin lin lc trc khi chuyn giao, gia S-GW v eNodeB, gia S-GW

v SGSN. Tn hiu ny c cha cc thng tin cn thit cu hnh ng i t S-

GW ti SGSN. Khi S-GW nhn c tn hiu ny, n s cu hnh mt con ng

thng tin t S-GW ti SGSN. Bng cch ny, ng thng tin lin lc s i t: S-

GW, SGSN, RNC, thit b u cui; v qu trnh truyn d liu cho h thng truy

cp v tuyn 3G bt u.Lu rng sau thi im ny, d liu chuyn tip l khng cn cn thit, do

, S-GW gi mt gi tin n cc eNodeB vi mt "End Marker" nh km, v khi

cc eNodeB nhn gi tin ny, n gii phng cc ti nguyn ca n lin quan n d

liu chuyn tip.Bc (9) - (10) : S-GW gi mt bn tin tr li v vic sa i sng mang ti

SGSN, ch ra th tc chuyn giao hon thnh. MME cng gii cc ti nguyn caeNodeB m khng cn cn thit.

Thng qua th tc bn giao, d liu c chuyn tip trong qu trnh chuyngiao, vic chuyn i sng mang truy nhp c hon thnh, v con ng thngtin lin lc t P-GW thit b u cui c cp nht.

Trong v d trn, m t cc th tc chuyn giao gia h thng truy cp v

tuyn 3GPP, trong S-GW khng thay i, nhng chuyn giao vi S-GW di

chuyn c th c. Trong nhng trng hp ny, P-GW cung cp chc nng

chuyn i ng truyn ging nh cc thit b chuyn mch cho cc h thng truy

cp non 3GPP.

2.8.6 Chuyn giao i vi LTE

H thng WCDMA s dng chuyn giao mm cho c ng ln v ng

xung. H thng HSPA s dng chuyn giao mm cho ng ln nhng khng s

dng cho ng xung. h thng LTE, khng s dng chuyn giao mm, ch c

chuyn giao cng, do h thng tr nn n gin hn.Trong h thng trc, mng li qun l RNC, RNC qun l cc trm BS v

BS li qun l cc UE. V th khi UE chuyn qua vng RNC khc phc v, th

mng li ch bit n RNC ang phc v UE. Mi chuyn giao c iu khin bi

RNCNhng i vi E-UTRAN, mng li c th thy mi chuyn giao.

53


Hnh 2-38: Cc loi chuyn giao

Chuyn giao cng tn s (intra-frequency) c thc hin gia cc cell trong

cng mt eNodeB. Chuyn giao khc tn s (intra-frequency) c thc hin gia

cc cell thuc cc eNodeB khc nhau.UE s thc hin trn d on o lng RSRP (Reference Signal Receive

Power) v RSRQ (Reference Signal Receive Quality) da trn tn hiu tham kho

RS (Reference Signal) nhn c t cell ang phc v v t cell nh hng mnh

nht. Gii thut chuyn giao da trn gi tr RSRP v RSRQ, chuyn giao c

thit lp khi cc thng s ny t cell nh hng cao hn cell ang phc v. WCDMA, chng ta dng CPICH RSCP quyt nh chuyn giao th

LTE ta s dng RSRP. RSRP l cng sut thu tn hiu tham kho, n l trung bnh

cng sut ca tt c cc thnh phn ti nguyn (mang tn hiu tham kho) qua ton

b bng thng. N c th c o lng tn hiu OFDM mang tn hiu tham

kho. o lng RSRP cung cp cng tn hiu c th ca cell. o lng ny

c s dng lm ng vo cho chuyn giao v quyt nh chn li cell. RSSI c

nh ngha nh tng cng sut bng rng nhn c quan st bi UE t tt c cc

ngun, bao gm cell phc v v cell khng phc v, can nhiu knh v nhiu nhit

trong bng thng o lng c th. RSSI khng c bo co khi o lng m n

c xem l ng vo tnh ton RSRQ. Vic o lng RSRQ cung cp cht lng

tn hiu ca cell c th. Ging nh RSRP, vic o lng ny c dng xc nh

cc ng c vin cell theo cht lng tn hiu ca chng. o lng ny c s

dng nh ng vo ca chuyn giao v quyt nh chn li cell, o lng RSRP

khng cung cp tin cy cho quyt nh chuyn giao. RSRQ c nh ngha

54


l t s N.RSRP/RSSI trong N l s RB ca bng thng o lng RSSI ca LTE.

Vic o lng ny c t s v mu s phi c thc hin vi cng s RB. Trong

khi RSRP ch ra mnh tn hiu, RSRQ b sung mc can nhiu bi v n bao gm

RSSI. V vy RSRQ cho php kt hp gia cng tn hiu vi can nhiu bo

co mt cch hiu qu.Khi thc hin o lng chuyn giao th chnh lch mc RSRP v

RSRQ phi mt mc chnh lch mi quyt nh chuyn giao. i vi 2 cell cng

tn s, chnh lch RSRP t +/- 2 dB n +/- 3 dB, chnh lch RSRQ t +/-

2,5 n 4 dB. i vi 2 cell khc tn s th chnh lch RSRP l +/- 6 dB,

chnh lch RSRQ t +/- 3 n 4 dB.

2.9 kt lun chng

Chng 2 khi qut c cu trc mng 4 GLTE, cc c tnh k thut v

cc k thut s dng trong LTE. Mng LTE c u im vt tri so vi 3G v tc

, thi gian tr nh, hiu sut s dng ph cao cng vi vic s dng bng thng

linh hot, cu trc n gin nn gi thnh gim. to nn cc u im , LTE

phi hp nhiu k thut, trong , n s dng k thut OFDMA ng xung.

Cc sng mang trc giao vi nhau, do tit kim bng thng, tng hiu sut s

dng ph tn v gim nhiu ISI. Cng vi cc u im th OFDM c khuyt

im l s thng ging ng bao ln dn n PAPR ln, khi PAPR ln th i hi

cc b khuch i cng sut tuyn tnh cao trnh lm mo dng tn hiu, hiu

sut s dng cng sut thp v th c bit nh hng i vi cc thit b cm tay.

Do , LTE s dng k thut SC-FDMA cho ng ln. Cng vi cc k thut ,

LTE cn h tr MIMO, MIMO l mt phn tt yu ca LTE t c yu cu v

thng lng v hiu qu s dng ph. Cng vi cc k thut ny, chng 2 cn

trnh by v lp biu ph thuc knh, thch ng ng truyn, HARQ vi kt hp

mm. ng thi cn bng cng sut pht i vi QoS yu cu, ti thiu can

nhiu v tng tui th pin ca thit b u cui, iu khin cng sut ng ln

c s dng LTE, iu khin cng sut kt hp c vng h v vng kn, nhng

do tnh trc giao ng ln ca LTE nn trnh c vn gn xa (vn in

55


hnh trong iu khin cng sut ca WCDMA) v v th LTE khng cn s dng

iu khin cng sut vng kn nhanh. Chuyn giao trong LTE, v chuyn giao gia

LTE vi cc mng khc.

56


CHNG 3 NI DUNG THC HIN

3.1 Tng quan v OMNeT++ v Mobility Framework

3.1.1 Gii thiu chung v OMNeT++ v Mobility Framework.

a) Gii thiu v Omnet++OMNeT++ l vit tt ca cm t Objective Modular Network Testbed in C+

+.OMNeT++ l mt ng dng cung cp cho ngi s dng mi trng tin hnh

m phng hot ng ca mng. Mc ch chnh ca ng dng l m phng hot

ng mng thng tin, tuy nhin do tnh ph cp v linh hot ca n, OMNeT++ cn

c s dng trong nhiu lnh vc khc nh m phng cc h thng thng tin phc

tp, cc mng kiu hng i (queueing networks) hay cc kin trc phn cng...

OMNeT++cung cp sn cc thnh phn tng ng vi cc m hnh thc t. Cc

thnh phn ny (cnc gi l cc module) c lp trnh theo ngn ng C++, sau

c tp hp li thnh nhng thnh phn hay nhng m hnh ln hn bng mt

ngn ng bc cao (NED). OMNeT++ h tr giao din ho, tng ng vi cc

m hnh cu trc ca n ng thi phn nhn m phng (simulation kernel) v cc

module ca OMNeT++ cng rt d dng nhng vo trong cc ng dng khc.b) Mobility Framework

Mobility l frame work c xy dng trn OMNeT++ nhm h tr m

phng mng v tuyn v di ng. Phn li ca frame work h tr di ng ca cc

nt, qun l kt ni ng v m hnh knh v tuyn. Thm vo , phn li ny cn

cung cp cc module c bn m ta c th da vo m xy dng module ca

mnh. Vi khi nim ny ngi lp trnh d dng m phng c giao thc ca

mnh da trn Mobility frame work.Frame work ny ch yu c dng m phng: Mng v tuyn c nh. Mng v tuyn ding. Mng tp trung v phn b. Mng cm bin. Mng v tuyn a knh. Nhiu s m phng khc m cn h tr di ng v giao din v tuyn.

c) Cc thnh phn chnh. Th vin phn nhn m phng (simulation kernel)

57


Trnh bin dch cho ngn ng m t hnh trng (topology description

language) Trnh bin tp ho (graphical network editor) cho cc file NED

(GNED) Giao din ho thc hin m phng, cc lin kt bn trong cc file thc

hin m phng (Tkenv) Giao din dng lnh thc hin m phng (Cmdenv) Cng c (giao din ho) v th kt qu vector u ra (Plove) Cng c (giao din ho) m t kt qu v hng u ra (Scalars) Cng c ti liu ho cc m hnh Cc tin ch khc Cc ti liu hng dn, cc v d m phngd) ng dng ca omnet++OMNeT++ l mt cng c m phng cc hot ng mng bng cc module

c thit k hng i tng. OMNeT++ thng c s dng trong cc ng

dng ch yu nh: M hnh hot ng ca cc mng thng tin. M hnh giao thc M hnh ho cc mng kiu hng i. M hnh ho cc h thng a b vi x l (multiprocesser) hoc cc h

thng phn cng theo m hnh phn tn khc (distributed hardware systems) nh gi kin trc phn cng. nh gi hiu qu hot ng ca cc h thng phc tp...

e) M hnh trong OMNeT++ v Mobility FrameworkMt m hnh trong OMNeT++ bao gm cc module lng nhau c cu trc

phn cp. su ca ca cc module lng nhau l khng gii hn, iu ny cho

php ngi s dng c th biu din cc cu trc logic ca cc h thng trong thc

t bng cc cu trc m hnh. Cc module trao i thng tin vi nhau thng qua

vic gi cc message (message). Cc message ny c th c cu trc phc tp tu .

Cc module c th gi cc message ny theo hai cch, mt l gi trc tip ti a

ch nhn, hai l gi i theo mt ng dn c nh sn, thng qua cc cng v

cc kt ni.

Cc module c th c cc tham s ca ring n. Cc tham s ny c th c sdng chnh sa cc thuc tnh ca module v biu din cho topology ca mhnh. Cc module mc thp nht trong cu trc phn cp ng gi cc thuc tnh.

58


Cc module ny c coi l cc module n gin, v chng c lp trnh trongngn ng C++ bng cch s dng cc th vin m phng.

3.1.2 Khi qut v Omnet++

a) Khi nim m hnh ha trong omnet++

OMNeT++ cung cp cho ngi s dng nhng cng c hiu qu m t

cu trc ca cc h thng thc t.

Cc module lng nhau c cu trc phn cpCc module l cc i tng c th ca cc kiu moduleCc module trao i thng tin bng cc message qua cc knhCc tham s ca module linh hotNgn ng m t topology

b) Cu trc phn cp ca cc module

Mt m hnh trong OMNeT++ cha cc module lng nhau c cu trc phncp, trao i thng tin vi nhau bng cch gi cc message. Mi m hnh nythng biu din cho mt h thng mng. Module mc cao nht trong cu trc phncp c gi l module h thng. Module ny c th cha cc module con, ccmodule con cng c th cha cc module con ca ring n. su phn cp i vicc module l khng gii hn, iu ny cho php ngi s dng c th d dng biudin mt cu trc logic ca mt h thng trong thc t bng cu trc phn cp caOMNeT++.

Cc module c th cha nhiu module con v c gi l module kt hp.Cc module n gin l cc module c cp thp nht trong cu trc phn cp. Ccmodule n gin cha cc thut ton ca m hnh. Ngi s dng trin khai ccmodule n gin bng ngn ng C++, s dng cc th vin m phng caOMNeT++.

Cu trc ca m hnh c th c m t bng ngn ng NED ca OMNeT++

59


Hnh 3-1: Cu trc lin kt ca mt chng trnh m phng trong OMNet++.c) Kiu module

Tt c cc module d l n gin hay phc tp u l cc i tng c thca cc kiu module. Trong khi m t cc m hnh, ngi s dng nh ngha ra cckiu module; cc i tng c th ca cc kiu module ny c s dng nh ccthnh phn ca cc kiu module phc tp hn. Cui cng, ngi s dng tomodule h thng nh mt i tng c th ca kiu module c nh nghatrc , tt c cc module ca mng u l module con (hoc l con ca modulecon) ca module h thng.

Khi mt kiu module c s dng nh mt khi dng sn (building block),

60


s khng th phn bit l mt module n gin hay phc tp. iu ny cho phpngi s dng c th tch cc module n gin ra thnh nhiu module n ginc nhng trong mt module kt hp, v ngc li c th tp hp cc chc nngca mt module kt hp trong mt module n gin m khng nh hng g ncc kiu module c ngi s dng nh ngha.

d) Message, cng, lin ktCc module trao i thng tin bng vic gi cc message. Trong thc t,

message c dng khung (frame) hoc l cc gi tin (packet) c truyn i trong

mng. Cc module n gin c th gi cc message i mt cch trc tip n v tr

nhn hoc gi i theo mt ng dn nh sn thng qua cc cng v cc lin kt.Thi gian m phng a phng (local simulation time) ca mt module

tng ln khi module nhn c mt message. Message c th n t mt module

khc hoc n t cng mt module (message ca chnh bn thn module - self-

message c dng thc hin b nh thi).Cng (gate) l cc giao tip vo ra ca module. Message c gi i qua cc

cng ra v c nhn vo thng qua cc cng vo.Mi kt ni (connection) hay cn gi l lin kt (link) c to bn trong

mt mc n trong cu trc phn cp ca cc module: bn trong mt module kt

hp, mt kt ni c th c to ra gia cc cng tng ng ca hai module con,

hoc gia cng ca module con vi cng ca module kt hp.

Hnh 3-2: Cc kt nie) M hnh truyn gi tin.

Mt kt ni c th c ba tham s c trng. Nhng tham s ny rt thun

tin cho cc m hnh m phng mng thng tin nhng khng hu dng lm cho cc

kiu m hnh khc. Ba tham s ny bao gm: tr ng truyn (propagation delay) tnh bng s - giy. T s li bit, c tnh bng s li/bit. T s d liu, c tnh bng s bit/s.

61


Cc tham s ny l tu chn. Gi tr ca cc tham s ny l khc nhau trn

tng kt ni, ph thuc vo kiu ca lin kt (hay cn gi l kiu ca knh truyn

channel type).

tr ng truyn l tng thi gian n ca message b tr i khi truyn

qua knh.

T s li bit nh hng n qu trnh truyn message qua knh. T s ny l

xc sut cc bit b truyn sai. Do xc sut mt message di n bit truyn i

chnh xc l:

P(message gi i c nhn chnh xc) = (1 - ber)n

trong ber l t s li bit v n l s bit ca message.

Cc message truyn i u c mt c li, c ny s c thit lp khi vic

truyn message c li.

T s d liu c tnh theo n v bit/s, v n c s dng tnh thi

gian truyn mt gi tin. Khi t s ny c s dng, qu trnh gi message i

trong m hnh s tng ng vi vic truyn bit u tin v message c tnh l n

ni sau khi bn nhn nhn c bit cui cng.

Hnh 3-3: Truyn messagef) Tham s

Cc module c th cc tham s.Cc tham s ny c th c t gi tr trong

cc file NED hoc cc file cu hnh ompnetpp.ini.

62


Cc tham s ny c th c dng thay i cc thuc tnh ca cc module

n gin hoc dng biu din cho topology ca m hnh.Cc tham s c th c kiu l chui, s hc, gi tr logic hoc cng c th

cha cy d liu XML (XML data tree). Cc bin kiu s trong cc biu thc c th

nhn gi tr t cc tham s khc, gi hm, s dng cc bin ngu nhin t cc ngun

phn tn hoc nhn gi tr trc tip c nhp vo bi ngi s dng.Cc tham s c kiu s c th c dng cu hnh topology rt d dng.

Nm trong cc module kt hp, cc tham s ny c th c dng ch ra s

module con, s cng giao tip v cch cc kt ni ni b c to ra.

3.1.2 S dng Omnet++

a) Xy dng v chy th cc m hnh m phng Mt m hnh OMNeT++ bao gm nhng phn sau:

- Ngn ng m t topology - NED (file c phn m rng .ned): m t cu

trc ca module vi cc tham s, cc cng... Cc file .ned c th c vit

bng bt k b son tho hoc s dng chng trnh GNED c trong

OMNeT++.- nh ngha cu trc ca cc message (cc file c phn m rng .msg):

Ngi s dng c th nh ngha rt nhiu kiu messsage v thm cc

trng d liu cho chng. OMNeT++ s dch nhng nh ngha ny sang

cc lp C++ y .- M ngun ca cc module n gin. y l cc file C++ vi phn m rng

l .h hoc .cc.b) H thng m phng cung cp cho ta cc thnh phn sau:

Phn nhn m phng. Phn ny cha code qun l qu trnh m phng v cc

th vin lp m phng. N c vit bng C++, c bin dch v c t cng

dng vi cc file th vin (cc file c phn m rng l .a hoc .lib). Giao din ngi s dng. Giao din ny c s dng khi thc hin qu trnh m

phng, to s d dng cho qu trnh sa li, biu din (demonstration) hoc khi thc

hin m phng theo tng khi (batch execution of simulations). C mt vi kiu

giao din trong OMNeT++, tt c u c vit bng C++, c bin dch v t

cng nhau trong cc th vin (cc file c phn m rng l .a hoc .lib).c) Thc hin m phng v phn tch kt qu

Cc chng trnh thc hin m phng (the simulation executable) l cc

63


chng trnh c lp, tc l n c th chy trn cc my khc khng ci t

OMNeT++ hay cc file m hnh tng ng. Khi chng trnh khi ng, n bt u

c file cu hnh (thng thng l file omnetpp.ini). File ny cha cc thit lp

iu khin qu trnh m phng thc hin, cc bin cho cc tham s ca m hnh...

File cu hnh cng c th c s dng iu khin nhiu qu trnh m phng,

trong trng hp n gin nht l cc qu trnh m phng ny s c thc hin ln

lt bi mt chng trnh m phng (simulation program).u ra ca qu trnh m phng l cc file d liu. Cc file ny c th l cc

file vector, cc file v hng hoc cc file ca ngi s dng. OMNeT++ cung cp

mt cng c ho Plove xem v v ra ni dung ca cc file vector. Tuy nhin

chng ta cng nn hiu rng kh m c th x l y cc file kt qu m ch

dng ring OMNeT++; cc file ny u l cc file c nh dng c th c c

bi cc gi x l ton hc ca cc chng trnh nh Matlab hay Octave, hoc c th

c a vo bng tnh ca cc chng trnh nh OpenOffice Calc, Gnumeric hay

Microsoft Excel. Tt c cc chng trnh ny u c chc nng chuyn dng trong

vic phn tch s ho, v biu din (visualization) vt qua kh nng ca OMNeT+

+.Cc file v hng cng c th c biu din bng cng c Scalar. N c th

v c cc biu , cc th da vo tp hp cc to (x, y) v c th xut d

liu vo clipboard c th s dng trong cc chng trnh khc nhm a nhng

phn tch chi tit hn.d) Giao din ngi s dng

Mc ch chnh ca giao din ngi s dng l che nhng phn phc tp bn

trong cu trc ca cc m hnh i vi ngi s dng, d dng iu khin qu trnh

m phng, v cho php ngi s dng c kh nng thay i cc bin hay cc i

tng bn trong ca m hnh. iu ny l rt quan trng i vi pha pht trin v

sa li trong d n. Giao din ho cng c th c s dng trnh din hot

ng ca m hnh.Cng mt m hnh ngi s dng c th trn nhiu giao din khc nhau m

khng cn phi thay i g trong cc file m hnh. Ngi s dng c th kim th

v sa li rt d dng qua giao din ho, cui cng c th chy n da trn mt

64


giao din n gin v nhanh chng c h tr thc hin theo khi (batch execution).e) Cc th vin thnh phn

Cc kiu module c th c lu ti nhng v tr c lp vi ch m chng

thc s c s dng. c im ny cung cp cho ngi s dng kh nhm cc

kiu module li vi nhau v to ra cc th vin thnh phn.f) Cc chng trnh m phng c lp

Cc chng trnh thc hin qu trnh m phng c th c lu nhiu ln,

khng ph thuc vo cc m hnh, s dng cng mt thit lp cho cc module n

gin. Ngi s dng c th ch ra trong file cu hnh m hnh no s c chy.

iu ny to kh nng cho ngi s dng c th xy dng nhng chng trnh thc

hin ln bao gm nhiu qu trnh m phng, v phn phi n nh mt cng c m

phng c lp. Kh nng linh hot ca ngn ng m t topology cng h tr cho

hng tip cn ny.

3.1.4 H thng file

Sau khi ci t OMNet++, th mc omnetpp trn h thng my ca bn nn

cha cc th mc con di y.H thng m phng:

omnetpp/ th mc gc ca OMNeT++bin/ cc cng c trong OMNeT++ (GNED, nedtool...)include/ cc file header cho m hnh m phnglib/ cc file th vinbitmaps/ cc biu tng hodoc/ cc file hng dn, readme...

manual/ file hng dn dng HTMLtictoc-tutorial/ gii thiu s dng OMNeT++api/ API tham chiu dng HTMLnedxml-api/ API tham chiu cho th vin NEDXMLsrc/ m ngun ca ti liu

src/ m ngun ca OMNeT++nedc/ nedtool, trnh bin dch messagesim/ phn nhn m phng

parsim/ cc file dnh cho vic thc hin phn tnnetbuilder/ cc file dnh cho vic c ng cc file NED

envir/ m ngun cho giao din ngi s dngcmdenv/ giao din ngi dng dng lnhtkenv/ giao din ngi s dng da trn Tcl/tkgned/ cng c son tho file NEDplove/ cng c v v phn tch u ra dng vector

65


scalars/ cng c v v phn tch u ra dng v hngnedxml/ th vin NEDXMLutils/ cc tin ch khc...

test/ b kim th licore/ b kim th li cho th vin m phngdistrib/ b kim th li

Cc qu trnh m phng mu c cha trong th mc samples

samples/ th mc cha cc m hnh m phng mualoha/ m hnh ca giao thc Alohacqn/ Closed Queue Network

...

Th mc contrib cha cc chng trnh c th kt hp vi OMNeT++

contrib/octave/ script ca Octave dng x l kt quemacs/ b nh du c php NED cho EmacsNgoi ra bn cng c th tm thy cc th mc khc nh msvc/, cha cc

thnh phn tch hp cho Microsoft Visual C++...

3.1.5 Import mt chng trnh

T kho import c s dng thm cc khai bo trong cc file m t

khc. Sau khi import, ngi s dng c th s dng tt c cc thnh phn

c nh ngha trong file m t .Ch khi thm mt file m t, ch c cc thng tin khai bo c s dng.

Cng tng t nh vy khi mt file c thm vo khng c ngha l n s c

dch khi file cha n c dch. Ngi s dng s phi dch tt c cc file ch

khng phi ch l file mc cao nht.C th xc nh mt file thm vo m c hoc khng vit phn m rng.V d: import mt chng trnh thnh cng:

import ethenet; //import ethernet.ned

Hay cng c th s dng ng dn trong khi s dng t kho import hoc

tt hn l bn s dng trnh bin dch ca NED vi tham s -I t tn cho th

mc cha cc file m bn mun import.

66


3.2 Thc hnh th nghim m phng

3.2.1 Ci t chng trnh m phng

a) Ci t Omnet++Download gi OMNeT++ 4.1 win32 vGii nn file zip va download vo th mc nh ci t OMNET (VD:

C:\omnetpp)Chy file mingwenv.cmd trong th mc omnetpp-4.1giao din dng lnh hin ra. Ti du nhc $ g 2 lnh sau:

$ ./configure $ make

Chng trnh s ci t tm t 10-50 pht, bao gi thy dng Now you

can type omnetpp to start the IDE l phn ci t hon thnh.Lu : trc khi ci nn ci t th vin h tr Java runtime (JRE).

Download: http://www.java.com b) Import Mobility Framework

Trn Menu bar chn Windows > Open Perspective > SimulationTrong ca s Project Explorer bm chut phi chn Import

Hnh 3-4: Ca s ImportCa s Import hin ra chn General>Existing Project into Workspace ri

next.

67


Hnh 3-5: chn ng dn n Project mun importTrong mc Select root directory chn ng dn ti th mc sample Mc Project chn cc Project mun importTick vao Copy project into Workspace copy lun cc th mc cha

Project vo Workspace y ti chn Mobility.Sau khi chn nhn Finish kt thc qu trnh importDi y l import thnh cng mt project

68


Hnh 3-6: Import mt chng trnh thnh cng

3.2.2 Thc hin th nghim m phng

H thng giao din chnh chng trnh chuyn giao mng LTE s dng

Mobility Framework trong file handoverLTE.ned

Hnh 3-7: H thng giao din chnh chng trnh Di y l code ca giao din h thng chng trnh, module ny chng

69


ta s gi li cc mudule con v t cc ta khc nhau.

network HandoverLTE{ parameters: double playgroundSizeX; double playgroundSizeY; submodules: UE: LTEUE { @display("p=50,130"); } eNodeA: LTE { @display("p=100,200"); } eNodeB: LTE { @display("p=500,200"); } channelcontrol: ChannelControl { playgroundSizeX = playgroundSizeX; playgroundSizeY = playgroundSizeY; @display("p=60,50"); } configurator: FlatNetworkConfigurator { @display("p=140,50"); }}

c c module trn th ti phi to ra nhng module con kt ni kt nichng vi nhau th di y l cc giao din v code thc thin kt ni giachng.

a) y l giao din module kt ni cc knh vi nhau

Hnh 3-8: giao din knh kt nisimple ChannelControl{ parameters: bool coreDebug = default(false); // debug switch for core framework double playgroundSizeX = default(600); // x size of the playground (in

70


meters) double playgroundSizeY = default(400); // y size of the playground (in meters) double pMax @unit("mW") = default(20mW); // maximum sending power used for this network (in mW) double sat @unit("dBm") = default(-110dBm); // signal attenuation threshold (in dBm) double alpha = default(2); // path loss coefficient double carrierFrequency @unit("Hz") = default(2.5GHz); // carrier frequency of the channel (in Hz) int numChannels = default(1); // number of radio channels (frequencies) string propagationModel = default("PathLossReceptionModel") @enum("","PathLossReceptionModel","TwoRayGroundModel","RiceModel","RayleighModel","NakagamiModel","FreeSpaceModel","LogNormalShadowingModel"); @display("i=misc/sun"); @labels(node);}Code trn c khai bo vi phng thc tnh, dng kt ni cc knhgia UE v eNode.

b) Module configurator

Hnh 3-9: giao in configuratorDi y l code giao din ca configurator

simple FlatNetworkConfigurator{ parameters: string networkAddress = default("192.168.0.0"); // network part of the address (see netmask parameter) string netmask = default("255.255.0.0"); // host part of addresses are autoconfigured @display("i=block/cogwheel_s"); @labels(node);}

Module ny c chc nng cu hnh a ch Ip cho UE v eNode kt ni vinhau.

c) Module UE

71


Hnh 3-10: giao din module UEModule ny l s kt hp ca nhiu module con li nh NetworkLayer

module ny c chc nng vn chuyn cc tcp, udp, ping n wan.NotificationBoard c chc nng cp nht v tr thay i khi UE di chuyn. Mobilityc nhim v cp nht v tr di chuyn ca UE. Di y l code giao din kt nica UE vi cc module.

module LTEUE{ parameters: @node(); @labels(node,ethernet-node,wireless-node); @display("i=device/cellphone2"); int numTcpApps = default(0); int numUdpApps = default(0); string tcpAppType = default(""); string udpAppType = default(""); bool IPForward = default(false); string routingFile = default(""); string mobilityType = default("NullMobility"); gates:

72


inout pppg[] @labels(PPPFrame-conn); inout ethg[] @labels(EtherFrame-conn); input radioIn @directIn; submodules: notificationBoard: NotificationBoard { parameters: @display("p=60,70"); } interfaceTable: InterfaceTable { parameters: @display("p=60,150"); } routingTable: RoutingTable { parameters: IPForward = IPForward; routerId = ""; routingFile = routingFile; @display("p=60,230"); } tcpApp[numTcpApps]: like TCPApp { parameters: @display("p=163,67"); } tcp: TCP { parameters: @display("p=163,154"); } udpApp[numUdpApps]: like UDPApp { parameters: @display("p=272,67"); } udp: UDP { parameters: @display("p=272,154"); } pingApp: PingApp { parameters: @display("p=343,200"); } networkLayer: NetworkLayer { parameters: proxyARP = false; @display("p=248,247;q=queue"); gates:

73


ifIn[(sizeof(pppg)+sizeof(ethg))+1]; ifOut[(sizeof(pppg)+sizeof(ethg))+1]; } ppp[sizeof(pppg)]: PPPInterface { parameters: @display("p=205,350,row,90;q=txQueue"); } eth[sizeof(ethg)]: EthernetInterface { parameters: @display("p=298,350,row,90;q=txQueue"); } wlan: Ieee80211NicSTA { parameters: @display("p=120,350;q=queue"); } mobility: like BasicMobility { parameters: @display("p=58,301"); } connections allowunconnected: for i=0..numTcpApps-1 { tcpApp[i].tcpOut --> tcp.appIn++; tcpApp[i].tcpIn networkLayer.tcpIn; tcp.ipIn udp.appIn++; udpApp[i].udpIn networkLayer.udpIn; udp.ipIn pingApp.pingIn; networkLayer.pingIn networkLayer.ifIn[i]; ppp[i].netwIn


}

for i=0..sizeof(ethg)-1 { ethg[i] eth[i].phys; eth[i].netwOut --> networkLayer.ifIn[sizeof(pppg)+i]; eth[i].netwIn wlan.radioIn; wlan.uppergateOut --> networkLayer.ifIn[sizeof(pppg)+sizeof(ethg)]; wlan.uppergateIn


parameters: @display("p=79,74"); } wlan: Ieee80211NicAP { // see also Ieee80211NicAPSimplified parameters: @display("p=110,179;q=queue"); } mobility: NullM

Documents

Tim Hieu Mang Lte Va Mo Phong Qua Trinh Chuyen Giao Tren Omnet