View
220
Download
0
Category
Preview:
Citation preview
7/31/2019 DO an -Khojduy
1/61
Ti u ha mng
B GIO DC V O TO CNG HA X HI CH NGHA VIT NAMTRNG I HC CNG NGHIP H NI
--------------------------------------------------c lp - T do - Hnh phc---------------------------------
NHIM V N TT NGHIP
H v tn sinh vin: ..... S hiu sinh vin:
Kho:.Khoa: Cng ngh in t Ngnh: .........
1. u n:....................................................................................................................................................................................................................................................................................................
2. Cc s liu v d liu ban u:
....................................................................................................................................................................................................................................................................................................
3. Ni dung cc phn thuyt minh v tnh ton:......................................................................................................................................................................................................................................................................................................................................................................................................................................................
4. Cc bn v, th ( ghi r cc loi v kch thc bn v ):......................................................................................................................................................................................................................................................................................................................................................................................................................................................
5. H tn ging vin hng dn: .6. Ngy giao nhim v n:.
7. Ngy hon thnh n:
Ngy thng nm
Ch nhim B mn Ging vin hng dn
Sinh vin hon thnh v np n tt nghip ngy thng nm
Cn b phn bin
Ngun Duy Khi in t 1 K31
7/31/2019 DO an -Khojduy
2/61
Ti u ha mng
B GIO DC V O TO
TRNG I CNG NGHIP H NI
---------------------------------------------------
BN NHN XT N TT NGHIP
H v tn sinh vin: ............................................ S hiu sinh vin: .....................................
Ngnh: ............................................................Kho: ..............................................................
Ging vin hngdn:..............................................................................................................
Cn b phn bin: Ni dung thit k tt nghip:
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
...................................................................................................................................
1. Nhn xt ca cn b phn bin:
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
................................................................................................................................
Ngy thng nmCn b phn bin
( K, ghi r h v tn )
Ngun Duy Khi in t 1 K32
7/31/2019 DO an -Khojduy
3/61
Ti u ha mng
LI M U
Thng tin lin lc l mt nhu cu ca bt k mt x hi pht trin no. p
ng nhu cu lin lc ngy cng cao ca x hi, thng tin di ng c nghin cu
pht trin t rt sm, bt u vi cc h thng thng tin di ng s dng cng ngh
analog, cho n nay cc mng di ng s dng cng ngh s c ng dng rng
ri v pht trin v cng mnh m.
Thng tin di ng ang trin khai Vit Nam bao gm 2 h.
+ S dng cng ngh GSM: MobiFone, VinaFone, Viettel, VietnamMobile,
Beeline (GTEL).
+ S dng cng ngh CDMA: EVN Telecom, v S-Fone.
Trong s lng thu bao s dng cng ngh GSM l p o.
ng trc s pht trin ca s lng thu bao trong thi gian ti v nhu cu
tng cao v cc dch v cao cp hn ca khch hng. Cc nh mng cn phi thchin m rng dung lng v nng cp cho mng li. Vic nghin cu v a ra cc
gii php k thut c kh nng p dng thc t v trin khai trong thi gian ngn l
v cng cn thit.
ti: Thit k xy dng trm BTS phc v cho mt vng v kim tra hot
ng trm BTS bng phng php o Driver Test
Trong qu trnh lm kha lun tt nghip, mc d em c gng nhiu nhng dotrnh c hn nn khng th trnh khi nhng sai st, em rt mong c s ph
bnh, gp ca thy c v bn b.
Trc khi trnh by ni dung ti ny, em xin chn thnh cm n ti cc thy
c trong b mn v tuyn cng nh cc thy c trong khoa Vt L thuc trng H
KHTN trang b cho em kin thc trong sut bn nm hc va qua.
c bit, em xin gi li cm n ti Thy V Thnh Thi tn tnh gip , trctip hng dn v to mi iu kin thun li cho em hon thnh kha lun.
Ngun Duy Khi in t 1 K33
7/31/2019 DO an -Khojduy
4/61
Ti u ha mng
Em cng chn thnh cm n ti anh Nguyn Thnh Hng, Trng Phng k
thut - cng ty C phn Pht trin Dch v Vin thng ITC cung cp ti liu v
hng dn em hon thnh kha lun.
Cui cng, l li cm n su sc em mun gi n gia nh cng bn b ng
vin gip em trong sut thi gian qua em c iu kin hon thnh tt nht kha
lun tt nghip ny.
Sinh vin thc hin
Ngun Duy Khi in t 1 K34
7/31/2019 DO an -Khojduy
5/61
Ti u ha mng
MC LC
Phn m u ...........................................................................................................................................................10
Phn 1......................................................................................................................................................................12TNG QUAN MNG DI NG........................................................................................................................12
Chng I ..................................................................................................................................................................12
MNG DI NG GSM .......................................................................................................................................12
Gii thiu chung ................................................................................................................................. ........ .......12
Cc c trng c bn ca h thng GSM ..........................................................................................................13
Cu trc mng GSM .............................................................................................................................. ........ ....14
...........................................................................................................................................................................14
1.1Chc nng cc khi trong h thng GSM ............................................................................................. ........14
CHNG II ...........................................................................................................................................................19
TNG QUAN V BTS .........................................................................................................................................19
Gii thiu chung v BTS ..................................................................................................................... ........ .......19
Cu trc chung ca h thng BTS ......................................................................................................................23
Nguyn l hot ng ca BTS .................................................................................................................... ........27
Phn 2......................................................................................................................................................................31
TI U HA MNG...........................................................................................................................................31
Chng 3 .................................................................................................................................................................32
DRIVE TEST TRONG MNG GSM ..................................................................................................................32
Mc ch ca vic thc hin Drive Test ...........................................................................................................32
Thit b o v th tc o drive test ....................................................................................................................32
4.3 Drive test trong chu trnh ti u ..................................................................................................................35
Chng 4 .................................................................................................................................................................38
4.1 Cc yu t nh hng n cht lng thoi ......................................................................................... .......394.2 Mt s k thut tng cht lng h thng: .................................................................................................43
Chng 5 Chuyn giao cuc gi v phn tch li handover ...........................................................................48
5.1 L thuyt ...........................................................................................................................................................48
5.1.1 Phn loi Handover ......................................................................................................................... ........48
5.1.2 Khi to th tc Handover ...................................................................................................................... .51
5.1.3 Quy trnh chuyn giao cuc gi ..................................................................................................... ........ ...52
5.2 o kim tra tri mt s trm li Handover .................................................................................................57
Ngun Duy Khi in t 1 K35
7/31/2019 DO an -Khojduy
6/61
Ti u ha mng
BNG K HIU VIT TT
AB Access Burst Cm truy nhp
AGCH Access Grant Channel Knh cho php truy nhp
AMPS Advanced Mobile Phone System H thng in thoi di ng tin tin
ARQ Automatic Repeat Request Yu cu lp li t ng
AUC Authentication Center Trung tm nhn thc
BCCH Broadcast Control Channel Knh iu khin qung b
BCH Broadcast Channel Knh qung b
BER Bit Error Rate T s bit li
BSC Base Station Controller B iu khin trm gc
BSIC Base Station Identity Code M nhn dng trm gc
BSS Base Station System H thng trm gc
BTS Base Transceiver Station Trm thu pht gc
C/A Carrier to adjacent ratio T s sng mang trn sng ln cn
C/I Carrier to interference ratio T s sng mang trn nhiu
CI Cell IdentityNhn dng xc nh v tr trong
vng nh v
C/R Carrier to reflection ratio T s sng mang trn sng phn x
CCCH Common Control Channel Knh iu khin chung
CCITT
International Telegraph &
Telephone Consultative
Committee
U ban t vn quc t v in thoi
v in bo
CEPT
European Conference of Postal
and Telecommunication
Lin minh chu u v bu chnh vin
thng
Ngun Duy Khi in t 1 K36
7/31/2019 DO an -Khojduy
7/61
Ti u ha mng
DCCH Dedicated Control Channel Knh iu khin ring
DCS Data Communication Subsystem Phn h thng tin s liu
DCS Digital cellular System H thng t ong s
EIR Equipment Identity Register Thanh ghi nhn dng thit b
ETSIEuropean Telecommunication
Standards Institude
Vin tiu chun vin thng chu u
FACCH Fast Associated Control Channel Knh iu khin lin kt nhanh
FB Frequency Correction Burst Cm hiu chnh tn s
FCCH Frequency Correction Channel Knh hiu chnh tn s
FDMAFrequency Division Multiple
Accessa truy nhp phn chia theo tn s
GMSC Gateway MSC MSC cng
GPRS General Packet Radio Service Dch v v tuyn gi chung
GSM
Global System for
Mobile Communication Thng tin di ng ton cu
HLR Home Location Register Thanh ghi nh v thng tr
IMEIInternational Mobile Equipment
IdentityNhn dng thit b di ng quc t
IMSIInternational Mobile Subscriber
IdentityNhn dng thu bao di ng quc t
ISDNIntegrated Service Digital
NetworkMng s a dch v
ISI Intersymbol Interference Nhiu giao thoa gia cc k hiu
IWF Inter Working Function Chc nng tng tc
LA Location Area Vng nh v
LAC Location Area Code M vng nh v
Ngun Duy Khi in t 1 K37
7/31/2019 DO an -Khojduy
8/61
Ti u ha mng
LAI Location Area Identity Nhn dng vng nh v
MCC Mobile Country Code M quc gia
ME Mobile Equipment Thit b di ng
MMS Multimedia Messaging Service Dch v nhn tin a phng tin
MNC Mobile Network Code M mng di ng
MOU Memoradum Uderstanding Bn ghi nh
MS Mobile Station Trm di ng
MSCMobile services Switching
Center
Trung tm chuyn mch cc dch v
di ng
MSISDN Mobile Station ISDN Number S ISDN trm di ng
MSRNMobile Station Roaming
NumberS lu ng trm di ng
NB Normal Burst Cm bnh thng
NMT Nordic Mobile Telephone in thoi di ng Bc u
OMCOperation and Maintenance
CenterTrung tm bo dng v vn hnh
OSS Operation and Support System H thng khai thc v h tr
PCH Paging Channel Knh tm gi
PCM Pulse Code Modulation iu ch xung m
PIN Personal Identification Number S nhn dng c nhn
PLMN Public Land Mobile Network Mng di ng mt t cng cng
PSPDNPacket Switch Public Data
Network
Mng s liu cng cng chuyn mch
gi
PSTNPublic Switched Telephone
Network
Mng in thoi chuyn mch cng
cng
RACH Random Access Channel Knh truy nhp ngu nhin
Ngun Duy Khi in t 1 K38
7/31/2019 DO an -Khojduy
9/61
Ti u ha mng
RAND Random number S ngu nhin
SACCHSlow Associated Control
ChannelKnh iu khin lin kt chm
SB Synchronization Burst Cm ng b
SCH Synchronization Channel Knh ng b
SDCCHStand alone Dedicated Control
Channel
Knh iu khin ring ng mt
mnh
SIM Subscriber Identity Module Mun nhn dng thu bao
SMS Short Message Service Dch v nhn tin ngnSRES Signed Response Mt khu
SS Switching System H thng chuyn mch
TACSTotal Access Communication
SystemH thng thng tin truy nhp ton b
TCH Traffic Channel Knh lu lng
TDMA Time Division Multiple Access a truy nhp phn chia theo thi gian
TMN Telecommunication
Management NetworkMng qun l vin thng
TRAU Transcoder/Rate Adaptation UnitKhi chuyn i m v thch ng
tc
VLR Visitor Location Register Thanh ghi nh v tm tr
CGI Cell Global Indentity Nhn dng ton cu
HNH V
Hnh v 2.1: Cu trc mng GSM.......................................................................................................................19
Hnh v 2.2: Cu hnh kt ni BTS ti BSC.......................................................................................................20
Ngun Duy Khi in t 1 K39
7/31/2019 DO an -Khojduy
10/61
Ti u ha mng
Hnh v 2.3: BTS MBI...........................................................................................................................................21
Hnh v 2.4: BTS MBO..........................................................................................................................................22
Hnh v 2.5: Cu trc chung ca h thng BTS.................................................................................................23
Hnh v 2.6: Kin trc khi SUMA......................................................................................................................24
Hnh v 2.7: Kin trc khi TRE.........................................................................................................................25
Hnh v 2.8: Kin trc khi ANC.........................................................................................................................26
Hnh v 2.9: Kin trc khi ANC.........................................................................................................................27
Hnh v 4.1: Chu trnh Drive Test........................................................................................................................37
Hnh 4-1 Intra-cell Handover..............................................................................................................................49
Hnh 4-2 Inter-cell Handover...............................................................................................................................50
Hnh 4-3 Intra-MSC Handover...........................................................................................................................50
Hnh 4-4 Inter-MSC Handover...........................................................................................................................51
Hnh 4-5 G 1: Trong lc kt ni, MS vn tip tc o c mc thu v cht lng truyn dn ca cellphc v v nhng cell xung quanh......................................................................................................................53
Hnh 4-6 Quyt nh chuyn giao_Handover Decision....................................................................................53
Hnh 4-7 G 1: BSC khai bo thng tin vi MSC............................................................................................54
Hnh 4-8 G 2: MSC1 yu cu MSC2 cp Handover Number.......................................................................55
Hnh 4-9 G 2: Cp m HON v knh v tuyn cho MSC1...........................................................................55
Hnh 4-10 G 3: MSC1 chuyn mch kt ni cho MS trn knh lu lng thit lp vi MSC2...............56
Hnh 4-11 Kt ni vi BTS c c gii phng ...............................................................................................57
Phn m u
Tm tt ni dung
Ngun Duy Khi in t 1 K310
7/31/2019 DO an -Khojduy
11/61
Ti u ha mng
Ngun Duy Khi in t 1 K311
7/31/2019 DO an -Khojduy
12/61
Ti u ha mng
Phn 1
TNG QUAN MNG DI NG
Chng I
MNG DI NG GSM
Gii thiu chung
Khi nim GSM c s dng ln u tin vo nm 1982, l ch vit tt ca
Groupe Speciale Mobile, l t chc thuc Hi ng Bu chnh v Vin thng Chu
u CEPT (Conference Europeenne des Postes et Telecommunications). T chc ny
c giao nhim v pht trin mt chun mi dng cho lin lc di ng trong di tn
900MHz, v kt qu ca n chnh l mng GSM ln u tin vo nm 1991. Trongnm ny, t GSM cng chuyn i ngha, tr thnh ch vit tt ca cm t H
thng thng tin di ng ton cu (Global System for Mobile Communications), v
ngi ta cng ra tiu chun cho mng GSM hot ng trong bng tn 1800MHz,
c gi l h thng DCS1800.
T n nay, nh c tnh chun ha rng ri trn ton th gii cng vi kh
nng chuyn vng quc t mnh m, GSM t c nhng thnh cng v cng to
ln trong s pht trin. Theo s liu bo co ca hip hi GSM GSMA (GSM
Ngun Duy Khi in t 1 K312
7/31/2019 DO an -Khojduy
13/61
Ti u ha mng
Association), tnh cho n thng 4 nm 2008, c 3 t thu bao di ng s dng
cng ngh GSM vi tng s 218 nh khai thc trn phm vi ton th gii.
Xut pht im ban u, GSM ch yu cung cp dch v thoi v d liu tc
thp, GSM cng c cc u im nh: tnh bo mt cao, kh nng chng nhiu mnh
m, hiu sut s dng ph cao. T h thng GSM ban u ch cung cp dch v thoi
l ch yu, GSM c tch hp thm cc chc nng nh gi tin nhn (SMS), hin
th s in thoi gi n, chuyn cuc gi p ng yu cu truyn d liu vi
tc cao, GSM c pht trin thm vi Dch v gi d liu v tuyn tng
qut GPRS (General Packet Radio Service), a tc truyn d liu trn c s
mng v tuyn GSM c th ln n 171.2 kbit/s.
Ngy nay, trc nhu cu ngy cng cao v thng tin di ng, c bit l cc ng dng
yu cu tc d liu cao, mng 3G l mt xu hng tt yu, trong GSM khng phi
l ngoi l. Trong qu trnh nng cp v dch chuyn , tnh hiu qu l yu
t v cng quan trng, do i hi s thay i ti thiu trong cu trc mng li,
c s h tng k thut mng. Theo l trnh c cc t chc chun ha a ra v
c cc nh khai thc chp nhn rng ri, mng GSM s tr thnh mng thng tin di
ng bng rng th h 3G vi mi trng truy nhp WCDMA trong tng lai.
Cc c trng c bn ca h thng GSM
+ GSM nguyn thu hot ng bng tn 900 MHz vi knh ng xung: 890-
915 MHz v knh ng ln: 935 - 960 MHz.
+ DCS 1800 (Digital Cellular System) hot ng bng tn 1800 MHz vi knh
ng xung: 1710 - 1785 MHz v knh ng ln: 1805 - 1880MHz.
+ PCS 1900 (Personal Communication Services) hot ng bng tn 1900 MHz
vi knh ng xung: 1850 - 1910 MHz v knh ng ln: 1930 - 1990 MHz.
+ Khong cch song cng (Khong cch gia tn s ln v tn s xung) ca
GSM 900, DCS1800 v PCS 1900 ln lt l 45MHz, 95MHz v 80MHz.
+ Khong cch gia cc knh ln cn (ng ln hoc ng xung) l 200 kHz.
Ngun Duy Khi in t 1 K313
7/31/2019 DO an -Khojduy
14/61
Ti u ha mng
+ Phng thc truy cp l TDMA cho php nhiu cuc gi khc nhau cng
chia s mt tn s.
Cu trc mng GSM
1.1 Chc nng cc khi trong h thng GSM
MS (Mobile station)
MS l thit b dng truy cp vo mng. Mt MS gm hai thnh phn chnh c
lp:
- Thit b u cui (ME - Mobile Equipment).
+ Thit b u cui bao gm in thoi di ng hoc mt thit b c th truy cp vo mng.
+ Mi in thoi di ng c phn bit bi mt s nhn dng in thoi di ng
IMEI (nternational Mobile Equipment Identity).
- SIM (Subcriber Identity Module)
Ngun Duy Khi in t 1 K3
BSC TRAU MSC
VLR
HLR
EIR AuC
Ccmngkhc:PSTN,PLMN,ISDN.
Abisinterface
Uminterface
Aterinterface
A interface
OMC
BSS
NSS
Hnh v 1.1: Cu trc mng GSM
14
MS BTS
7/31/2019 DO an -Khojduy
15/61
Ti u ha mng
+ SIM l mt card thng minh dng nhn dng u cui. u cui khng th
hot ng nu khng c SIM. SIM lu tr cc thng tin lin quan n thu bao di
ng, cc dch v GSM v cc thng tin lin quan n PLMN.
+ Card SIM cha mt s nhn dng thu bao di ng IMSI (International
Subcriber Identity) h thng nhn dng thu bao, mt mt m xc thc v cc
thng tin khc.
+ Card SIM c th chng vic s dng tri php bng mt khu hoc s nhn
dng c nhn (PIN).
BSS (Base Station System - H thng trm gc)
BSS thc hin cc chc nng lin quan n v tuyn trong h thng. N qun l
vic lin lc v tuyn vi cc khi di ng. N cng x l vic handover ca cc
cuc gi gia cc cell. BSS chu trch nhim qun l tt c cc ti nguyn mng v
tuyn v d liu v cu hnh cell. BSS trong CME 20 v CMS 40 u c kh nng x
l cc li thng thng m khng cn phi c s iu khin t OSS.
BSS gm mt BSC v mt s BTS.
BTS (Base Transceiver Station - Trm thu pht gc)
BTS bao gm tt c cc thit b v tuyn v cc thit b giao tip truyn dn v
tuyn phc v cho mt cell v tt c cc BTS u chu s qun l ca BSC.
Cc chc nng chnh ca BTS l:
- Cung cp kt ni vi MS
-X l tn hiu
-X l bo dng cc b.
-Kim tra v gim st.
Hu ht cc hot ng chnh BTS u c BSC iu khin.
Ngun Duy Khi in t 1 K315
7/31/2019 DO an -Khojduy
16/61
Ti u ha mng
BSC (Base Station Controller- Trm iu khin gc)
BSC iu khin mt nhm BTS v qun l ti nguyn v tuyn. BSC chu trch
nhim iu khin vic handover, nhy tn, cc chc nng tng i v iu khin cc
mc cng sut, tn s v tuyn ca BTS c th l:
- Qun l mng v tuyn:
Qun l d liu m t cell, cu hnh cell, thng tin h thng v d liu nh v.
+ o c lu lng v cc knh ri.
+ Ghi li lu lng.
+ Chia s ti cell.
- Qun l cc trm v tuyn gc:
+ nh cu hnh cho BTS.
+ Thay i chc nng v ti chng trnh cho cc BTS.
+ Bo dng cc thit b BTS.
- Qun l mng truyn dn:
+ Chuyn i v thch ng tc trong BSC.
+ Vn hnh v bo dng bn trong BSC:
+ iu khin s kt ni gia cc MS: gm cc qu trnh tm gi, thit lp kt
ni bo hiu, ch nh knh lu lng, nh v, handover, iu khin cng sut ng
trong MS v BTS, nhy tn, dch v nhn tin qung b v tin vn.
NSS (Network Switching System - H thng chuyn mch)
H thng chuyn mch NSS chu trch nhim qun l s thng tin gia ngi s
dng mobile n nhng i tng s dng khc nh n cc thu bao di ng, n
mng ISDN, PSTN... N cn cha cc d liu cn thit lu tr thng tin v thu
bao.
Ngun Duy Khi in t 1 K316
7/31/2019 DO an -Khojduy
17/61
Ti u ha mng
MSC (Mobile Service Switching Centre-Trung tm chuyn mch dch v di ng)
Nhim v chnh ca MSC l iu phi vic thit lp cuc gi n nhng ngi
s dng mng GSM. Mt mt MSC giao tip vi h thng con BSS, mt khc giao
tip vi mng ngoi. MSC thc hin cc chc nng sau:
- Thit lp v iu khin, phn phi cuc gi, cc bn tin ngn.
- X l cuc gi lin tc khi chuyn giao.
- Cp nht v tr, v d liu ca MS.
- Bo hiu gia cc thnh phn ca mng v gia cc mng khc nhau.
- Qun l xc nh c im d liu v x l MS.
- Kim tra IMEI v tnh cc
HLR (Home Location Register - Thanh ghi nh v thng tr)
HLR l mt c s d liu lu tr v qun l cc thng tin v thu bao. Trong
PLMN c nhiu HLR. i vi mi thu bao thuc vng ph sng ca MSC, HLR
cha d liu v thu bao nh: cc s ng k, danh sch dch v c ng k s
dng bi thu bao. HLR cng lu tr v cp nht cc thng tin ng v thu bao, baogm thng tin v v tr thu bao (a ch ca VLR), cc dch v c ng k ca
thu bao, cc s c tip tc gi, cc cuc gi b cm.
VLR (Visitor Location Register - Thanh ghi nh v tm tr)
VLR l mt c s d liu v tt c cc thu bao hin ang nh v vng dch v
ca MSC. N cha cc thng tin tm thi ca MS MSC c th cung cp cc dch
v cho cc MS ang c phc v. Khi MS di chuyn sang vng dch v mi caMSC th VLR kt ni vi MSC mi s yu cu ly v lu thng tin v MS t
HLR. Khi MS thc hin mt cuc gi th VLR cha sn cc thng tin cn thit
cho vic thit lp cuc gi.
VLR lun c tch hp vi MSC c th thc hin bo hiu bn trong. iu
ny lm loi b cc bo hiu khng cn thit gia hai nt mng, do lm gim lu
lng bo hiu trong mng.
AuC (Authentication Centre Trung tm nhn thc)
Ngun Duy Khi in t 1 K317
7/31/2019 DO an -Khojduy
18/61
Ti u ha mng
Thanh ghi AuC c dng cho mc ch bo mt. N cung cp cc tham s cn
thit cho chc nng nhn thc v to mt m (ciphering). Cc tham s ny gip xc
minh s nhn dng thu bao.
EIR (Equipment Identity Register)
EIR c dng cho mc ch bo mt. N l mt thanh ghi lu tr cc thng tin
v cc thit b mobile. C th hn l n lu tr danh sch cc u cui hp l. Mt
u cui c nhn dng bng mt IMEI. EIR cho php cm cc cuc gi t cc u
cui b nh cp hay khng c php.
MSC cng (GMSC)
thit lp mt cuc gi n ngi s dng GSM, trc ht cuc gi phi c
nh tuyn n mt tng i cng c gi l GMSC m khng cn bit n hin
thi thu bao ang u. Cc tng i cng c nhim v ly thng tin v v tr ca
thu bao v nh tuyn cuc gi n tng i ang qun l thu bao thi im hin
thi (MSC tm tr).
1.1.1 Khi TRAU
Khi TRAU l khi chuyn i tc knh thoi TRAU (Transcoder/Rate
Adapter Unit), khi ny thc hin chc nng chuyn i tc v ghp 4 knh thoi
t trm BTS c tc 16Kb/s thnh mt knh PCM 64Kb/s trc khi giao tip vi
MSC. Mc d c xem l mt phn t ca mng truy nhp nhng TRAU thng
t chung v tr vi MSC gim chi ph kt ni truyn dn.
Ngun Duy Khi in t 1 K318
7/31/2019 DO an -Khojduy
19/61
Ti u ha mng
CHNG II
TNG QUAN V BTS
Gii thiu chung v BTS
Khi nim v BTS
BTS l mt thit b dng pht tn hiu ra mi trng v tuyn n cc my di
ng v thu tn hiu t cc my di ng cng thng qua mi trng v tuyn. N
thng tin n cc MS thng qua giao din v tuyn Um v kt ni vi b iu khin
trm gc BSC (Base Station Controller) thng qua giao din Abis.
V tr ca BTS trong h thng GSM
CAUTRUCMANG GSM
Radio tow er
Radio tower
BSC
T
C
M
F
S
SGN
HLR
BTS
BTS
GGSN
PSTN
INTERNET
IPGPRSBACKBONE
BSS
OMC-R
MSC
S trn m t v tr ca BTS trong h thng mng GSM. Cc BTS c t
khp ni trong vng c k hoch ph sng v n c kt ni ti b iu khin trm
gc BSC (Base Station Controller). Ngoi ra v tr ca BTS cn ph thuc vo cu
hnh kt ni ti BSC, chng hn nh c cc cu hnh sau:
19
CU TRC MNG GSM
Hnh v 2.1: Cu trc mng GSM
7/31/2019 DO an -Khojduy
20/61
Ti u ha mng
- Sectorised configuration
- Multipion configuration
- Chain configuration
- Star configuration
Phn loi BTS
Thit BTS b m cng ty ta s dng khu vc pha nam l loi thit b A9100
ca hng ALCATEL n gm c 2 loi chnh l:MBI
L loi BTS dng trong phng kn, trong loi BTS ny li chia thnh 2 dng,
l dng nh MBI3, n ch gm c 3 subrack vi trng lng ln nht l 150kg; loi
cn li l MBI5 n gm c 5 subrack vi trng lng ti a l 270kg. Kch thc v
hnh dng c c m t nh sau:
20
Hnh v 2.2: Cu hnh kt ni BTS ti BSC
7/31/2019 DO an -Khojduy
21/61
Ti u ha mng
Mi Subrack c th lp t 8 SUMA, 4 TRE, 3 ANC.
21
Hnh v 2.3: BTS MBI
7/31/2019 DO an -Khojduy
22/61
Ti u ha mng
MBO
L loi BTS c th t ngoi tri v cng ging nh BTS MBI n cng c 2
dng l MBO1 vi trng lng ln nht l 255kg v MBO2 l dng m rng ca
MBO1 vi trng lng ti a l 425kg. Kch thc v hnh dng c m ta m t
nh sau:
Cng tng t nh MBI, MBO cng c nhng tng qut v khu vc dng u
ni cp tn hiu v cp cnh bo. Ngoi ra n cn c thm cc khu vc dng lp
t acqui v nhng khu vc dng cho vic lp t cc thit b truyn dn.
22
Hnh v 2.4: BTS MBO
7/31/2019 DO an -Khojduy
23/61
Ti u ha mng
Cu trc chung ca h thng BTS
Cu trc chung ca h thng BTS
CLOCK
T
R
A
NS
OMU
SUM
TRE AN
Abis
BTS-TE
H thng BTS gm c cc khi chc nng chnh sau:
+ SUMA
+ TRE
+ ANC
Cu trc v chc nng ca cc khi chnh trong h thng BTS
Khi SUMA
- XCLK (External clock): l giao din tn hiu ng h ng b bn ngoi. Tn
hiu ny c th c ly t mt tn hiu tham chiu bn ngoi nh: Abis link, GPS,
BTS khc, c th c to ra trong kiu xung ri bi mt b pht tn s bn trong.
- CLKI: l h thng ng h ch c phn phi ti TRE v AN.
- MMI: thng qua serial link kt ni ti BTS Terminal, thc hin qun l
li, tc ng trc tip n h thng bng mt s lnh n gin.
23
Hnh v 2.5: Cu trc chung ca h thng BTS
7/31/2019 DO an -Khojduy
24/61
Ti u ha mng
- XBCB: External BTS control bus l bus iu khin cnh bo ngoi(Alarm).
- BCB: BTS control bus: Bus nay mang thng tin v trng thi, cu hnh, cnh
bo n cc Module trong BTS.
- BSII: mang thng tin TCH, RSL, OML, IOM-CONF.
- SUMA: l khi trung tm ca mt BTS, mt BTS ch c mt SUMA bt k s
sector v TRX l bao nhiu.
Transmission
& Clock
O&M
RI
BSII
SWITCH
2 Mbit/s2 Mbit/s2 Mbit/s
XBCB BCB
MMI
Abis 1
XCLOCK
External interface Internal interface
CLKI
BSII 0,1
KIEN TRUC SUMA
SUMA c cc chc nng chnh sau:
- Qun l link truyn dn Abis (ln n 2 giao din Abis).
- To xung ng h cho tt c cc modul BTS, cc ng h ny c th c
ng b t mt ng h tham chiu bn ngoi: Abis link, GPS, BTS khc, c th
c to ra trong kiu xung ri bi mt b pht tn s bn trong.
- Thc hin chc nng vn hnh v bo dng cho BTS
- Qun l ghp cc d liu TCH, RSL, OML, QMUX
- iu khin chc nng AC/DC khi chng c tch hp bn trong BTS
- iu khin ngun (dung lng, in p, nhit )
24
Hnh v 2.6: Kin trc khi SUMA
7/31/2019 DO an -Khojduy
25/61
Ti u ha mng
- Thit lp in p v dng cho vic np pin.
Khi TRE
KIEN TRUC C SCUA TRE
TRED
TREA
TREPPSI
RFI
CLKI
BSII
BCB PSWITCH
LEDS
DEBUG
RCD CUI I2CA
Module TRE bao gm ba khi chnh nh trn. Khi TRE-A (Analog) thu tn hiu t
Antenna chuyn thnh tn hiu sTRE-D (Digital) a ti SUMA, v ngc li.
- TRED:
H thng TRED chiu trch nhim v phn s ca TRE:
+ X l iu khin v bo hiu, n chu trch nhim qun l cc chc nng
O&M ca TRE.
+ Ghp knh, nhy tn, mt m v gii mt m.
+ M ho (DEC).
+ Gii iu ch (DEM).
+ M ho v pht (ENCT).
+ u cui BCB.
- TREA:
25
Hnh v 2.7: Kin trc khi TRE
7/31/2019 DO an -Khojduy
26/61
Ti u ha mng
+ iu ch
+ iu khin v bin i cao tn phn pht (TXRFCC).
+ ng b phn pht (TXSYN).
+ Bin i trung tn phn thu (RXIF).
+ ng b phn thu (RXSYN).
+ Gii iu ch trung tn (ISD).
+ TRE PA board bao gm b khuch i cng sut, n m nhim khuch i
cng sut tn hiu cao tn bi TXRFCC.
+ TREP: Cung cp ngun cho TRE (DC/DC)
Khi ANC
COMBINING MODE
Duplexer
Filter Filter
LNA
Spliter
Duplexer
Filter Filter
LNA
Spliter
Spliter SpliterSpliterSpliterWBC WBC
ANTA ANTB
TRE 1
TX RX RXd
TRE 2
TX RX RXd
TRE 3
RXd RX TX
TRE 4
RXdRX TXBridgeBridge
ANC kt ni 4 my thu - pht n 2 antenna.
Phn phi tn hiu nhn c t mi antenna n 4 my thu - pht (thu thng v
thu phn tp)
Modul ny bao gm 2 cu trc ging nhau, mi cu trc bao gm:
+Antenna: n c chc nng l pht sng ra mi trng v tuyn v thu sng t
my di ng pht n.
26
Hnh v 2.8: Kin trc khi ANC
7/31/2019 DO an -Khojduy
27/61
Ti u ha mng
+ Filter: Lc b tn hiu khng cn thit.
+ Mt khi duplexer: dng kt hp hai hng pht v thu mt antenna.
+ Mt khi LNA: khi ny c chc nng khuch i tn hiu m antenna thu
c ln mc ln cho TRE c th x l c.
+ Hai khi Spliter: khi ny c chc nng tch tn hiu thu ca TRE.
+ WBC: (Wide band combiner) b ny c chc nng kt hp hai ng pht li
vi nhau i trn cng mt ng n b duplexer. Thc t ta ch dng b
ny khi ta dng hn 2 TRX trn cng mt sector, nu khng dng kt hp th ta
phi g cu ra v kt ni trc tip vi duplexer m khng thng qua b WBC.
Khi qua b WBC tn hiu s b suy hao l 3.3 dBm.
Nguyn l hot ng ca BTS
Kt ni cc khi chc nng trong h thng BTS
Giao tip bn trong BTS c thc hin thng qua cc bus BCB v BSII.
BSII 1
BSII 2
BTS TERM
Abis
KET NOI BEN TRONG
OMU
TRANS& CLOCK
TRE ANx ANy
FACB
AC/DC&BATTEIES
ISL ISL ISL
ISL ISL
TRE FW/SW O&M/TELECOM
ANx FW
ISL pilot
EBCB
BSC
OML/IOM/IOM -CONF
TCH/RSL
BCB (Base Station Control Bus)
BCB: Bus iu khin BTS c kt ni n tt c cc module trong BTS.
27
Hnh v 2.9: Kin trc khi ANC
7/31/2019 DO an -Khojduy
28/61
Ti u ha mng
N c s dng trao i thng tin gia SUMA v cc module khc. Bus ny
ch s dng cho mc ch vn hnh v bo dng.
BSII (Base Station Internal Interface)
BSII l giao din chnh bn trong BTS
BSII c s dng mang cc loi thng tin sau:
- TCH (Traffic Channel): Mi TCH chim mt Nibble 16kbit/s(Full rate), hoc
8kbit/s(harf rate) trong lung PCM 30.
- RSL (Radio Signalling Link): Cho php ghp mt vi thng tin trn cng mt
kt ni vt l nh: Trn TS 64kbit/s c th mang thng tin v Telecom, O&M hayQ_mux (gia TRE v SUMA).
- OML (Operation Maintenance Link): Cho php ghp mt vi thng tin trn
cng mt kt ni vt l nh: Trn knh 64kbit/s c th mang thng tin v Telecom,
O&M hay Q_mux (gia BSC v SUMA).
Nguyn l hot ng ca BTS
Nguyn l hot ng ca BTS da trn qu trnh x l cc tn hiu m n nhn
c t my di ng (MS) v t BSC.
Tn hiu t BSC a ti BTS thng qua giao din Abis trn ng truyn PCM
gm c cc tn hiu sau:
- Tn hiu thoi TCH (traffic channel).
- Tn hiu bo hiu RSL (radio signalling link).
- Tn hiu vn hnh bo dng OML (operation maintenance link).
- Tn hiu truyn dn Q_mux.
Cc tn hiu ny c phn b trn khung PCM nh sau:
Khi khng s dng ghp
Cu hnh chain end
TS0
28
7/31/2019 DO an -Khojduy
29/61
Ti u ha mng
TCH TCH TCH TCHTCH TCH TCH TCH
TS31
- Trong cu trc khung PCM th khe thi gian TS0 c s dng cho mc ch
ng b.
TS31 c s dng truyn tn hiu OML, Qmux.
+ Cc khe thi gian cn li c s dng truyn d liu TCH, tn hiu RSL.
+ Cc khe thi gian trong khung PCM c chia thnh 4 nibble mi nibble
16Kbps c s dng cho mt knh lu lng TCH.
Trong khung PCM giao din Abis th mt RSL chim ton b mt khe thi
gian trong khung v s RSL ph thuc vo s TRX m mt BTS c. Tc l s lng
ca RSL s bng s TRX.
+ Trong khung PCM cn c tn hiu OML tn hiu ny s dng trong qu trnh
khai thc v bo dng. S lng ng OML s ph thuc vo s BTS. Mi
OML s phc v ch cho mt BTS
+ Vic n nh cc TS c thc hin t di ln (T TS31TS1)
Cu hnh chain: Tng t nh cu hnh chain end tc l thng tin OML v Qmux
cng c ghp trn cng mt TS v vic n nh thng tin cng c thc hin t
TS31TS1. V d c 2 trm BTS cu hnh 1/1 th vic n nh thng tin trn khung
PCM nh sau:
TSo
TCH TCH TCH TCH
TS31(OML2+Qmux2)
29
7/31/2019 DO an -Khojduy
30/61
Ti u ha mng
TS25(RSL2)
TCH TCH TCH TCH
TCH TCH TCH TCH
TS28(RSL1)
TCH TCH TCH TCH
TCH TCH TCH TCH
TS31(OML1+Qmux1)
Khi s dng kiu ghp ny th vic n nh cc thng tin vo cc TS ty thuc
vo tng cu hnh tuy nhin n theo xu hng l lm th no hn ch vic ghp
nhiu RSL vo mt TS. N ch s dng ghp 4RSL + 1OML khi lu lng trn
lung PCM c s dng ti a.
- Cc tn hiu ny u tin c a n khi SUMA v kt cui ti phn truyn
dn ca khi ny, sau n a n cc khi chc nng khc s l nh sau:
+ Tn hiu Qmux c kt cui ti phn truyn dn, thc hin qu trnh iu
khin truyn dn.Thng tin Qmux c ghp chung vi thng tin OML trn
cng mt TS
+ Cc tn hiu v vn hnh bo dng th kt cui ti khi OMU, khi nhn
thng tin O&M, x l v a ra cc lnh lin quan n qu trnh vn hnh bo dng.
+ Cc tn hiu v lu lng v bo hiu s c a n khi TRE y s
thc hin qu trnh x l thoi v sau a n ANC ri ti antenna ri pht
ra mi trng v tuyn.
30
7/31/2019 DO an -Khojduy
31/61
Ti u ha mng
Phn 2
TI U HA MNG
31
7/31/2019 DO an -Khojduy
32/61
Ti u ha mng
Chng 3
DRIVE TEST TRONG MNG GSM
Mc ch ca vic thc hin Drive Test
Thc hin Drive Test nhm nh gi cht lng v tuyn ca cc im/trm/khu
vc/vng nhm pht hin v x l cc tn ti trn mng di ng v nh hng cho
vic lp k hoch nhm tng cng ph sng ti cc im/trm/khu vc/vng o.
Thit b o v th tc o drive test
i Drive test
i Drive test phi cn t nht 2 ngi, mt li xe v mt k s Drive test. Ngi
li xe phi cn hiu c ng ph v cu trc ca khu vc cn o, v nh vy li
xe c th cung cp thng tin v tuyn ng c th v cung cp nhng thng tin c
th thay i.
3.4 Thit b Drive test v cc ngun h tr
3.4.1 Thit b Drive test
Thit b Drive test gm c:
- Mt phn mm o (TEMS) v mt my tnh xch tay
- Mt in thoi di ng test (T610 Ericsson)
32
7/31/2019 DO an -Khojduy
33/61
Ti u ha mng
- Mt GPS
- Ngun in cung cp (c ni vi Acqui ca xe chuyn i in thnh
220V cho my tnh v GPS)
- Cp d liu kt ni gia Laptop v my TEMS
- H thng antenna (anten gn t ng hng c cp ni vi in thoi)
Tems 8.0 v cp d liu GPS Holux
My tnh xch tay B i ngun DC - AC
3.4.2 Cc ngun h tr
- t phi c ngun lm vic n nh v acqui hot ng tt
- Mt bn ng ph cho php nh hng ng i
- V tr ca Site v cu hnh chi tit, c th trn cc bn ring r hoc trn bn
c th ch ra Azimuth, titls, cao v cc thng s cn thch hp khc
- S ng i, bao gm c bn ng ph v hng ch dn
- Mt simcard test
- Mt file m t mng vi nh dng tng ng vi phn mm cn o (CDD)
- Even Log m k s c th ghi ch cc s kin v thi gian a im m c th
nh hng n c chnh xc ca php o (v d nh i trong ng ngm cu
cao), nhng thng tin ny c th s dng cho vic phn tch li sau ny
33
7/31/2019 DO an -Khojduy
34/61
Ti u ha mng
Th tc o
Cc th tc chun b
ng i phi c xc nh cn thn trc khi thc hin, ng i l nh nhautrong sut qu trnh ti u. Cc im sau phi c cn nhc khi ln k hoc o:
- Khong thi gian ti a cho mi cluster l 4h. s cuc gi >=200 c th
cung cp mt s liu ng tin cy
- ng i phi bao gm tt c cc Cells ca mt cluster
- Nu c th ng i phi c ln k hoch c th i c handover c 2 chiu
- t nht tt c cc tuyn ng chnh phi c o
- ng i vo cc vng m khng c trn bn s th khng cn thit o
Trc khi Drive test c tin hnh tt c cc thng tin bao gm cao, gc v
hng anten phi c kim tra li. Nhng vn v ci t phi c gii quyt
trc khi thc hin php o.
Cc site cha hot ng cn phi c lu v nu cn thit c th hon li php
o v thay i tuyn ng
3.5.2 Ci t thit b
Cc li ngt ngun trong php o c th sinh ra li d liu khi tin hnh php o.
Vi mc ch ngn nga cc hin tng trn phi m bo rng my tnh xch
tay, in thoi test v GPS phi c np in. Kim tra tt c cc kt ni vi ngun
an ton cha v b chuyn i khng b qu ti.
H thng Anten c s dng v v tr anten c th thay i:
+ o mc tn hiu trn ng hoc kim tra mc tn hiu cho trc,
Anten phi c t trn nc ca xe khng gn hn 45cm t bt c cnh no.
Nu chiu cao ca xe ln hn 1.8m, th c th t Anten trn np y my t
v khng gn hn cnh no 45cm v cch knh chn gi l 1m.
+ o c tnh trong xe Antenna c th t mt v tr c nh ngang u li xe
34
7/31/2019 DO an -Khojduy
35/61
Ti u ha mng
Mt qui tc rt quan trng cn phi nh l gi cho cc thit b o c n
nh sut qu trnh o. iu ny m bo cho mt kt qu chnh xc.
Kim tra tt c cc kt ni m bo rng phn mm o c kt ni vi
cc thit b.
Kim tra xem phn mm o c th thu c cc bn tin lp ba v cc php o
khc t MS hay khng.
Ci t ch cuc gi theo th tc sau khi o bench marking l thi gian thit
lp cuc gi l 90s, ch 25s v lp li
Lu logfile vo v tr qui nh trn my tnh vi nh dng MMDDYY_Name.
3.5.3 Qu trnh kim tra
Bi v khi khi ng xe s c mt xu hng lm rt in th acqui do sinh ra
li hiu in th trn hu ht cc Inverter. Do vy cn phi gi xe chy lin tc trong
sut qu trnh cn o.
Tin hnh thc hin o ti mt tc xe c nh nu c th nhng khng qu
60km/h. Khong thi gian di dng li cn c ghi ch bi v c th sinh ra trn
mt vng mt kt qu sai lch c th rt tt cng c th rt xu.
Trong sut qu trnh o, k s nn quan st bn ngoi xem xt li (sai fio,
mc tn hiu thp, ci t Antena hoc vt chn) v ni no cn thit th ghi ch li
kim tra li.
m bo rng logfile c bt u v kt thc khi MS trng thi ri; iu ny
ngn nga s thng k sai.
4.3 Drive test trong chu trnh ti u
C 2 ngun c th cho mt k s s dng gim st mng li, bng di
y s th hin li u im cng nh nhc im ca 2 ngun ny.
c im Chi ph hiu qu Phm vi vt l
Field Test
measurement
Th hin mt ci
nhn ca khch hng
Tiu tn nhiu thi
gian
Trong mt vng gii
hn tt cho xc nh
35
7/31/2019 DO an -Khojduy
36/61
Ti u ha mng
mc tiu v cht
lng mng ph hp
cho phn tch i th
cc vn - xc nh
c l hng vng
ph sng
NMS/OMC Cho php la chn d
liu tp trung. Thng
tin lin tc, c ch cho
gim st.
Mt cch hiu qu
qun l cht
lng mng
V tr gii hn c th
xc nh cc vn
trong tng cell.
Trong qu trnh trc khi a vo khai thc, s lng cc thu bao nh nn vic
thu c cc thng k t NMS l khng ng k. Tuy nhin, cc thng bo khc ca
NMS nh Equipment Alarm l rt hu ch pht hin cc vn c th v cngcung cp cu tr li cho c tnh mng c tm thy trong Drive Test.
Ngoi ra cn c ngun d liu c ly t cc thng bo Measurement Report
c ly t MS v cc o c ng ln c ly t BTS khi knh c kch hot.
Acalter RMS v Ericson MRR l 2 h thng c th cung cp su hn v cc vn
nh la chn d liu nh Timing Advance Distribution, S phn b ca tn hiu
trn ng xung v ng ln, s phn b RxQual v s gim bt hoc iu khincng sut, cc d liu ny c th c biu din ring r hoc kt hp vi nhau
pht hin ra vn . V d nh RxQual v RxLev c th ch ra c vn vng
nhiu do mc tn hiu thp hoc do k hoch n nh tn s km.
Chu trnh ti u
36
7/31/2019 DO an -Khojduy
37/61
Ti u ha mng
4.3.1 Drive test
4.3.1.1 K hoch kho st kim tra
Nhm RNP t chc cc i v cc thit b tin hnh kho st o c, bi v
hnh ng ny tiu tn rt nhiu thi gian, do c th phi thm nhn lc. Trong
trng hp ny nhm RNP s hng dn i kho st c th tp trung nhiu hn vo
phn tch cc kt qu php o
37
Hnh v 4.1: Chu trnh Drive Test
7/31/2019 DO an -Khojduy
38/61
Ti u ha mng
4.3.1.2 nh dng tuyn ng kim tra
Nhm s xc nh tuyn ng cho nhm kho st, nhng tuyn ng ny nn
nht qun v nn xem trc ch vi thng hoc nhng vng c kh nng thay i
V d s thay i gm c: tch hp site mi, cc nh cao tng mi xy dng,
nhng con ng mi.
Trong trng hp c thm ngi tin hnh php o, RNP nn a ra mt form
yu cu php o vi bn km theo.
4.3.1.3 La chn php o
i Drive test nn iu khin php o tun theo hng dn k hoch v nhng
tuyn ng c xc nh bi RNP.
Cc i nn ghi ch li nhng vn v thit b v cc s kin khng bnh
thng khc (sai phi ) v thng bo n cc i tng ng. Nu cc vn c
sa cha ngay ti im , i o nn tin hnh tip tc Drive Test, nu khng th
php o phi c hon li vo ngy khc.
4.3.2 Phn tch d liuS phn tch ca nhm Drive test s cho php nhm RNP c th quyt nh c
tnh mng, pht hin ra cc vn v khuyn co thay i ci thin mng.
kt ni tt c cc ngun ca d liu l rt cn thit c mt s kim tra hon
chnh ca cc giai on mng lui sau ny. Phn ny m t mt s li thng thng
c tm thy trong mng li v cch gii quyt.
Chng 4
MT S YU T NH HNG N
CHT LNG TN HIU
38
7/31/2019 DO an -Khojduy
39/61
Ti u ha mng
4.1 Cc yu t nh hng n cht lng thoi
Mt c im ca cell l cc knh ang s dng c th c s dng cc
cell khc. Nhng gia cc cell ny phi c mt khong cch nht nh. iu ny c
ngha l cell s b nhiu ng knh do vic cc cell khc s dng cng tn s. Cui
cng vng ph sng ca trm gc s b gii hn bi l do ny hn l do tp m thng
thng. V vy, ta c th ni rng mt h thng t ong hon thin l gii hn c
nhiu m c qui chun, loi tr c nhiu h thng. Mt vn trong thit k
h t ong l iu khin cc loi nhiu ny mc chp nhn c. iu ny c
thc hin mt phn bi vic vic iu khin khong cch s dng li tn s. Khong
cch ny cng ln th nhiu cng b.
cht lng thoi lun c m bo th mc thu ca sng mang mong
mun C (Carrier) phi ln hn tng mc nhiu ng knh I (Interference) v mc
nhiu knh ln cn A (Adjacent).
4.1.1 Nhiu ng knh
Hnh 2.1: Nhiu ng knh.
Nhiu ng knh xy ra khi c hai my pht pht trn cng mt tn s hoctrn cng mt knh. My thu iu chnh knh ny s thu c c hai tn hiu vi
cng ph thuc vo v tr ca my thu so vi hai my pht.
T s sng mang trn nhiu c nh ngha l cng tn hiu mong mun
trn cng tn hiu nhiu.
C/I = 10log(Pc/Pi) .
Trong :
39
7/31/2019 DO an -Khojduy
40/61
Ti u ha mng
Pc = cng sut tn hiu thu mong mun
Pi = cng sut nhiu thu c.
Hnh 2.2: T s nhiu ng knh C/I.
Hnh 2.1 trn ch ra trng hp m my di ng (cellphone) t trong xe
ang thu mt sng mang mong mun t mt trm gc phc v (Serving BS) v ng
thi cng ang chu mt nhiu ng knh do nhiu pht sinh ca mt trm gc khc(Interference BS).
Gi s rng c hai trm u pht vi mt cng sut nh nhau cc ng
truyn sng cng tng ng (hu nh cng khng khc nhau trong thc t) v
im gia, my di ng c C/I bng 0 dB, c ngha l c hai tn hiu c cng
bng nhau. Nu my di ng i gn v pha trm gc ang phc v n th C/I > 0 dB.
Nu my di ng chuyn ng v pha trm gy ra nhiu th C/I < 0 dB.
Theo khuyn ngh ca GSM gi tr C/I b nht m my di ng vn c th lm
vic tt l 9 dB. Trong thc t, ngi ta nhn thy rng gi tr ny cn thit phi ln
n 12 dB ngoi tr nu s dng nhy tn th mi c th lm vic mc C/I l 9dB.
mc C/I thp hn th t l li bit BER (Bit Error Rate) s cao khng chp nhn
c v m ho knh cng khng th sa li mt cch chnh xc c.
T s C/I c dng cho cc my di ng ph thuc rt ln vo vic quy
hoch tn s v mu ti s dng tn s. Ni chung vic s dng li tn s lm dung
40
7/31/2019 DO an -Khojduy
41/61
Ti u ha mng
lng tng ng k tuy nhin ng thi cng lm cho t s C/I gim i. Do vic
quy hoch tn s cn quan tm n nhiu ng knh C/I.
4.1.2 Nhiu knh ln cn
Nhiu knh ln cn xy ra khi sng v tuyn c iu chnh v thu ring
knh C song li chu nhiu t knh ln cn C-1 hoc C+1. Mc d thc t sng v
tuyn khng c chnh thu knh ln cn , nhng n vn ngh mt s p
ng nh l cho php knh ln cn gy nhiu ti knh m my thu ang iu chnh. T
s sng mang trn knh ln cn c nh ngha l cng ca sng mang mong
mun trn cng ca sng mang knh ln cn.
C/A = 10.log(Pc/Pa)
Trong :
Pc = cng sut thu tn hiu mong mun
Pa = cng sut thu tn hiu ca knh ln cn
Gi tr C/A thp lm cho mc BER cao. Mc d m ho knh GSM bao gm
vic pht hin li v sa li, nhng vic thnh cng th cng c gii hn ivi nhiu. Theo khuyn ngh ca GSM, cho vic quy hoch tn s c tt th gi
tr C/A nh nht nn ln hn - 9 dB.
Khong cch gia ngun to ra tn hiu mong mun vi ngun ca knh ln
cn ln s tt hn cho C/A. iu ny c ngha l cc cell ln cn khng nn c n
nh cc sng mang ca cc knh cnh nhau nu C/A c c ngh trong
mt gii hn nht nh.
C hai t s C/I v C/A u c th c tng ln bng vic s dng quy hoch
cu trc tn s.
4.1.3 Phn tn thi gian
Phn tn thi gian xy ra l do c nhiu ng truyn sng t my pht n
my thu. Hin tng phn tn thi gian gy ra mt s vn cho mng thng tin di
ng s. Vic s dng truyn dn s cng gy ra mt s vn khc nh: phn tnthi gian do cc tn hiu phn x (Reflection) gy ra.
41
7/31/2019 DO an -Khojduy
42/61
Ti u ha mng
Hnh 2.3: S phn tn thi gian.
S phn tn thi gian s gy ra hin tng giao thoa gia cc k t. Githit chng ta pht i mt chui bit 1 v 0. Nu tn hiu phn x i chm hn tn hiu
i thng ng 1 bit th my thu pht hin bit 1 t sng phn x ng thi cng pht
hin bit 0 t sng i thng.
Ca s thi gian c nh ngha l khong thi gian 15 ms sau khi my thu
nhn c tn hiu trc tip t my pht. Gi s cc tia phn x n my thu bn
ngoi ca s thi gian, tc l sau 15 ms, s gy phin phc cho h thng ging nh l
nhiu.Ta bit gi tr ti thiu ca C/I trong h thng GSM l 9 dB.
Chng ta c th coi gi tr ny l gi tr cc i ca phn tn thi gian. Ngha
l tt c cc tn hiu phn x m n tr hn 15 ms, bn ngoi ca s thi gian, phi
c gi tr tng nh hn 9 dB. T s ny chnh l C/R.
Phn tn thi gian ch c th xy ra khi hiu qung ng gia tn hiu trc
tip v tn hiu phn x t nhng chng ngi vt k trn ln hn ca s cn bng
(4,5 km).
Ni chung, s nguy him ca phn tn thi gian s tng cng vi khong cch
gia BTS v MS. Khi mt MS gn BTS c th nhn c tn hiu phn x mnh vi
hiu qung ng ln nhng vn khng nh hng g do tn hiu trc tip mnh
m bo t s C/R trn ngng ti hn. Khi MS chuyn ng ra xa BTS th nguy c t
s C/R thp s tng ln do tn hiu trc tip yu i.
42
7/31/2019 DO an -Khojduy
43/61
Ti u ha mng
Tuy nhin, mt iu cn ch l tia phn x cng l mt phn ca sng
mang cho nn vic quy hoch mt h thng cn phi ch ra c cc trng hp c
th c th xy ra hin tng giao thoa k t.
4.1.4 Nhiu gia cc h thng
Trong mt vi trng hp cng c th b nhiu t cc ngun nhiu ngoi, nh t
cc h thng GSM khc c tn s ln cn nhau, hoc t cc ng vi ba c hoc cc
h thng ca qun i c cng tn s hoc gn bng tn GSM. Loi nhiu ny thng
kh x l, v phi c quan tm trong qu trnh thit k tn s c bin php trnh
nhiu trn h thng tng trm v tng vng c th.
4.1.5 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.
- Nguyn nhn: Multipath cung l mt nguyn nhn gy ra fading ngoi ra
cn nhiu nguyn nhn khc nh kh hu thi tit, s phn x ca cc sng ti tng
in ly.....
- Phn loi fading
Fading phng.
Fading chn lc tn s.
- gim phn no tc hi do Fading gy ra, ngi ta thng tng cng sut
pht ln to ra mt lng d tr Fading, s dng mt s bin php nh: phntp anten, nhy tn ...
4.2 Mt s k thut tng cht lng h thng:
4.2.1 iu khin cng sut thu pht ca MS v BTS:
- iu khin cng sut nhm cc tiu ha nhiu ng knh v bo tn cng
sut trm di ng v trm thu pht gc hot ng vi mc cng sut thp nht m
vn duy tr cht lng tn hiu chp nhn c.
43
7/31/2019 DO an -Khojduy
44/61
Ti u ha mng
- Cho php iu khin cng sut hng xung, BTS ch pht cng sut max
ti khe thi gian mang BCCH, cc TCH c iu chnh ti u theo yu cu cng
sut.
- Trm di ng o cng tn hiu hoc cht lng tn hiu v chuyn
thng tin n b iu khin trm gc BSC, cui cng quyt nh c thay i mc
cng sut hay khng v khi no.
- MS c iu khin cng sut nhm tit kim pin v gim nhiu hng ln.
- iu khin cng sut phi cn thn v c kh nng dao ng. iu ny xut
hin khi mt di ng trong cc cell ng knh nhn c tn hiu tng mc cng sut
trong cell ang xt ( trit nhiu ng knh) lm tng thm nhiu ng knh cellang xt.
4.2.2 Truyn pht gin on (DTX):
Thc cht ca phng php DTX (Discontinuous Transmission ) l BTS hay
MS ch pht khi nhn c tn hiu u vo (tn hiu thoi) v khi kt thc tn hiu
n s ngng pht.
Mc ch ca phng php ny l tit kim nng lng v gim nhiu trn
knh ln cn mt cch ti a.
Khi s dng phng php truyn dn gin on ta cn thm cc thit b ph
tr khc nh VAD (Voice Active Detector) pht hin tn hiu vo v to ra ting
n gi khi mt pha no ngng cung cp tn hiu.
4.2.3 Nhy tn:
Khi nim nhy tn
Mt tp hp cc tn s c s dng trong mi t bo v MS c th thay i
cc tn s ngay trong mi khung TDMA c gi l nhy tn. Tc nhy tn
trong h thng GSM l 217 ln/s.
c im chung ca k thut nhy tn
- Ch c cc knh SDCCH/8, TCH, v knh d liu gi c php nhy tn.
44
7/31/2019 DO an -Khojduy
45/61
Ti u ha mng
- Khe thi gian s 0 mang knh BCCH ca sng mang BCCH (sng mang f0)
khng c php nhy tn cho d n thuc v nhm knh c nhy tn, v cho
php cc thu bao cc cell ln cn thc hin o lng trong ch ri.
u im ca k thut nhy tn
Lm gim nh hng ca fading a ng, ca nhiu nn cht lng thoi
c ci thin, lm cho qu trnh s dng li tn s cht ch v hiu qu hn.
4.2.4 Chia cell
Kch thc Cell v phng thc ph sng
Cell ln: Bn knh ph sng khong: n km n*10 km (GSM: 35
km)
V tr thit k cc Cell ln:
- Sng v tuyn t b che khut (vng nng thn, ven bin )
- Mt thu bao thp.
- Yu cu cng sut pht ln.
Cell nh: Bn knh ph sng khong: n*100 m. (GSM: 1 km)
V tr thit k cc Cell nh:
- Sng v tuyn b che khut (vng th ln).
- Mt thu bao cao.
- Yu cu cng sut pht nh.
C tt c bn kch thc cell trong mng GSM l macro, micro, pico v
umbrella. Vng ph sng ca mi cell ph thuc nhiu vo mi trng.
Macro cell c lp trn ct cao hoc trn cc to nh cao tng.
Micro cell li c lp cc khu thnh th, khu dn c.
45
7/31/2019 DO an -Khojduy
46/61
Ti u ha mng
Pico cell th tm ph sng ch khong vi chc mt tr li n thng c lp
tip sng trong nh.
Umbrella lp b sung vo cc vng b che khut hay cc vng trng gia cc
cell.
Chia Cell (Cells Splitting)
Mt cell vi kch thc cng nh th dung lng thng tin cng tng. Tuy
nhin, kch thc nh i c ngha l cn phi c nhiu trm gc hn v nh th chi
ph cho h thng lp t trm cng cao hn.
Khi h thng bt u c s dng s thu bao cn thp, ti u th kch
thc cell phi ln. Nhng khi dung lng h thng tng th kch thc cell cng
phi gim i p ng vi dung lng mi. Phng php ny gi l chia cell.
Hnh 2.4: Phn chia Cell.
Ty theo nhu cu v lu lng v mt thu bao gia cc vng m c s
chia cell khc nhau cho ph hp vi cu trc mng ca vng .
4.2.5 cao v gc nghing ca anten (down tilt):
nhng khu vc th trn nh hay nng thn, lu lng ca h thng thp nn
vic ti s dng tn s l khng cn thit. Do vy, ta nn s dng cc v tr cao hay
t anten cao ti a ho vng ph sng.
Tuy nhin nhng khu vc th ln, lu lng h thng cao, kch thc cell
hp th c l thch hp nht l gim cao anten c th lm gim can nhiu knh
46
7/31/2019 DO an -Khojduy
47/61
Ti u ha mng
chung. Tuy nhin, nu t qu thp, cc vt cn (nh cao tng...) s c nh hng ln
ti cht lng h thng. Do vy, hin nay cao anten cc th thng l
30 50m. gii quyt phm vi vng ph sng hp, mt k thut c a ra l
lm nghing hng bp sng chnh ca anten (down tilt).
Vic nghing gc anten c th dng gii quyt vn ph sng. Tuy nhin
vic p dng nghing gc anten cn c s phn tch k cng nhng yu t lin quan
c th xy ra trong vng ph sng.
4.2.6 Ti s dng tn s
Ton b di tn pht cho mng GSM 900Mhz l t 890Mhz-915Mhz tc l c
25Mhz, c chia thnh 125 knh thoi c th s dng cng lc, mi knh c
rng l 200Khz. Mi knh thoi li c chia nh thnh 8 khe thi gian, trong c
1 khe dnh cho tn hiu bo hiu-iu khin v 7 khe cn li dnh cho MS. Nh vy
tng s MS c th lin lc trong cng mt thi im l 7*125 = 875.
Tuy nhin i vi mt mng di ng th con s 875 thu bao lin lc ng thi
l qu t i. V th m "Ti s dng tn s ra i", y l phng php nhm tng s
lng thu bao c th lin lc cng mt thi im ln n con s hng triu.
Ti s dng tn s : Cc nhm tn s ging nhau c th c s dng cc
cell khc nhau min sao khong cch gia cc cell ln trnh nhiu do cc tn s
trng nhau gy ra.
Hnh 2.5: Ti s dng tn s.
47
7/31/2019 DO an -Khojduy
48/61
Ti u ha mng
C ba kiu mu s dng li tn s ph bin l: 7/21, 4/12 v 3/9 s dng cho cc
trm gc c anten pht 3 hng, mi hng dnh cho mt v gc phng v phn
cch nhau 1200. Mi s dng cc anten pht 600 v hai anten thu phn tp 600 cho
mt gc phng v. Mi c xp x ho l hnh lc gic, c bn knh R (bng cnhhnh lc gic v bng 1/3 khong cch gia cc trm).
4.2.7 Chuyn giao cuc gi (Handover)
Mt tr ngi trong vic pht trin mng thng tin di ng t bo l vn pht
sinh khi mt thu bao di ng di chuyn t cell ny sang cell khc. Cc khu vc k
nhau trong h thng t bo s dng cc knh v tuyn c tn s khc nhau, khi thu
bao di ng di chuyn t cell ny sang cell khc th cuc gi hoc b rt hoc t ngchuyn t knh v tuyn ny sang mt knh khc thuc cell khc.
Thay v cuc gi b rt, qu trnh Handover (ting M: Handoff) gip cho
cuc gi c lin tc. Qu trnh Handover xy ra khi h thng thng tin di ng t
ng chuyn cuc gi t knh v tuyn ny sang knh v tuyn khc khi thu bao di
ng di chuyn t cell ny sang cell khc lin k vi n. Trong qu trnh m thoi,
hai thu bao cng chim mt knh thoi. Khi mt thu bao di ng chuyn ng ra
khi vng ph sng ca cell cho trc, tn hiu u thu ca cell ny s gim. Khi ,
cell ang s dng s yu cu mt Handover (chuyn giao) n h thng. H thng s
chuyn mch cuc gi n mt cell c tn s vi cng tn hiu thu mnh hn m
khng lm gin on cuc gi hay gi cnh bo n ngi s dng. Cuc gi s
c tip tc m ngi s dng khng nhn thy qu trnh Handover din ra.
Chng 5 Chuyn giao cuc gi v phn tch li handover
5.1 L thuyt
5.1.1 Phn loi Handover
H thng phn loi cc qu trnh chuyn giao cuc gi thnh nhng loi sau:
Intra-cell Hand Over.
Inter-cell Hand Over.
Intra-MSC Hand Over.
48
7/31/2019 DO an -Khojduy
49/61
Ti u ha mng
Inter-MSC Hand Over.
Intra-cell Hand Over (Chuyn giao trong ni b t bo): Th tc
chuyn giao thc hin gia hai knh vt l ca cell ang phc v.
Intra-cell Hand Over khng c s dng khi thu bao di chuyn sang cell
khc, ngoi tr trng hp nu mc nhiu trn knh ring l cao th mt s chuyn
giao sang mt knh vt l khc phi c thc hin.
Hnh 4-1 Intra-cell Handover
Inter-cell Hand Over (Chuyn giao lin t bo): MS c chuyn mch
sang mt knh v tuyn mi ca mt cell khc nhng c iu khin ca cng mt
b iu khin trm gc BSC.
49
7/31/2019 DO an -Khojduy
50/61
Ti u ha mng
Hnh 4-2 Inter-cell Handover
Intra-MSC Hand Over (Chuyn giao trong ni b MSC): Chuyn mch
knh v tuyn gia hai BSC ca cng mt tng i di ng MSC.
Hnh 4-3 Intra-MSC Handover
Inter-MSC Hand Over (Chuyn giao lin MSC): Chuyn mch knh v
tuyn gia hai tng i di ng MSC.
50
7/31/2019 DO an -Khojduy
51/61
Ti u ha mng
Hnh 4-4 Inter-MSC Handover
Trong trng hp ny, MSC ban u gi ton quyn iu khin cuc gi v
sp t truy nhp mng cho n khi kt thc cuc gi. Cuc gi c nh tuyn vt
l li t MSC ban u trc tip n MSC ch.
5.1.2 Khi to th tc Handover
Th tc Handover s c khi to vo bt k lc no mi khi xut hin nhu
cu chuyn i ng v tuyn gia BSS v MS sang mt knh mi, c th l cng
BSS hay mt BSS khc. BSS s nhn thy yu cu thit lp th tc Handover duy
tr s lin tc ca cuc gi trong khi MS di chuyn.
Nu cell ch u tin nm trong cng BSC th th tc Handover s c thc
hin bi BSC. Nu khng, BSC s gi n MSC mt danh sch u tin cc cell ch.
Trong danh sch ny, MSC ch cn nhc n ba cell u tin.
Gii thut MSC (vi v d l c ba cell c cn nhc) l bc th nht s th
vi cell u tin, nu khng c th s chuyn sang th vi cell th hai ri th ba,
m khng c vic tnh n nhng kha cnh lu lng. Nu nh trong khi th tc
handover ny ang din ra m c thm mt yu cu Handover khc nhn c t
BSC, danh sch s c cp nht tnh ton n cc cell mi. Vi mi ln th,
51
7/31/2019 DO an -Khojduy
52/61
Ti u ha mng
MSC yu cu mt ti nguyn tn s thch hp ti phn h trm gc BSS ch m theo
mc nh l khng cho php vic xp hng i, hoc l cho php hng i nu cho
php nu nh c ch th tng ng trong yu cu handover nhn c t BSS ngun.
Nu nh MS khng hon thnh vic t c mt knh mi t cell ch th n
s gi mt bn tin thng bo chuyn giao tht bi thng qua cell trc ti mng
li v MSC s hi phc li kt ni trc ca MS hoc nu MSC nhn thy MS
mt kt ni th cuc gi s c gii phng.
5.1.3 Quy trnh chuyn giao cuc gi
V c bn, th tc Handover bao gm 4 giai on:
Giai on 1: BSC quyt nh thc hin th tc handover
m bo kt ni ca cuc gi.
Giai on 2: Mt kt ni mi c thit lp, song song vi kt
ni gc.
Giai on 3: MSC chuyn cuc gi sang kt ni mi.
Giai on 4: Kt ni gc c gii phng.
Giai on 1:
52
7/31/2019 DO an -Khojduy
53/61
Ti u ha mng
Hnh 4-5 G 1: Trong lc kt ni, MS vn tip tc o c mc thu v cht lng
truyn dn ca cell phc v v nhng cell xung quanh.
Nhng kt qu o c c gi ti BSC v l cn c yu cu mt th tc
Handover sang mt cell khc c mt cht lng truyn dn tt hn.
Hnh 4-6 Quyt nh chuyn giao_Handover Decision
Handover Margin: Thc cht ca Handover Margin l s chnh lch gia
mc thu ca cell ang phc v v cc cell ln cn. Khi mc thu ca mt cell ln cn
no vt qu mc thu ca cell ang phc v mt khong ln hn gi tr Handover
Margin nh sn th mt Handover Alarm s c gi v h thng nhm a n
quyt nh chuyn giao. Thng thng th th tc Handover s c thc hin ngay
sau .
Nu vic t gi tr Handover Margin qu thp s dn ti vic Handover qu
nhiu, nhng ngc li khi gi tr ny t qu ln c th lm cho cht lng cuc gi
b gim xung.
V vy, ty vo tnh cht ph sng ca tng vng cng nh mc nhiu ca
tng cell phc v, Handover Margin cn c iu chnh thch hp t c cht
53
7/31/2019 DO an -Khojduy
54/61
Ti u ha mng
lng tt nht. V d nh vng b nhiu nhiu c th t gi tr Handover Margin
thp MS c th nhanh chng chuyn giao sang cell khc c cht lng tt hn.
Gi tr khuyn ngh l 4 dB, trn mng VMS_Mobifone hin ang s dng
Handover Margin l 5 dB.
BSC s thng bo cho MSC v s cn thit thc hin th tc Handover, v
khai bo thng tin vi MSC1.
Hnh 4-7 G 1: BSC khai bo thng tin vi MSC
Giai on 2:
MSC1 yu cu mt Handover Number (HON) t MSC2 v thng bo vi
MSC2 thng tin v cell B.
54
7/31/2019 DO an -Khojduy
55/61
Ti u ha mng
Hnh 4-8 G 2: MSC1 yu cu MSC2 cp Handover Number
M HON (Handover Number) ch quan trng trong trng hp Inter-MSC
Handover. N c dng MSC1 thit lp kt ni knh lu lng vi MSC2. Cu
trc ca m HON cng ging nh m MSRN v cng c cung cp bi VLR mi.
MSC2 yu cu VLR cung cp mt m HON, ng thi yu cu BSC cung cp
knh v tuyn. Sau , knh v tuyn v m HON c gi li cho MSC1.
Hnh 4-9 G 2: Cp m HON v knh v tuyn cho MSC1
55
7/31/2019 DO an -Khojduy
56/61
Ti u ha mng
Giai on 3:
Hnh 4-10 G 3: MSC1 chuyn mch kt ni cho MS trn knh lu lng thit lp
vi MSC2
Vi m HON, MSC1 c th thit lp knh lu lng kt ni vi MSC2.
MSC1 thng bo cho MS v knh v tuyn m n phi chuyn mch ti.
Giai on 4:
Gii phng kt ni vi BTS c.
56
7/31/2019 DO an -Khojduy
57/61
Ti u ha mng
Hnh 4-11 Kt ni vi BTS c c gii phng
5.2 o kim tra tri mt s trm li HandoverCng vi cc cng c khc, my TEMS c s dng thng xuyn trong
vic o v kim tra cht lng h thng.
Di y gii thiu vic s dng my TEMS ca Ericsson o kim tra t trm
Hng Thi.
57
7/31/2019 DO an -Khojduy
58/61
Ti u ha mng
58
7/31/2019 DO an -Khojduy
59/61
Ti u ha mng
KT LUN
ti ca n trnh by nhng nt c bn nht v mng thng tin di ng
GSM, nghin cu chc nng, nhim v, cu hnh phc v nhm p ng lu lng
ca trm BTS s dng dng sn thit b ca hng Alcatel-lucent cng vi vic thc
hin Drive Test trong cng tc ti u ha h thng cho mng VMS Mobifone. ti
l mt cng vic kh khn v i hi ngi thc hin phi nm vng h thng thit
b, ngoi ra cng cn phi c nhng kinh nghim thc t v tnh ton v s tr gip
ca nhiu phng tin hin i c th gim st v kim tra ri t mi a ra
cc cng vic thc hin.
Qua thi gian thc hin em thy ti Thit k xy dng trm BTS phc
v cho mt vng v kim tra hot ng trm BTS bng phng php o
Driver Test l mt mng ti rng v lun cn thit cho cc mng vin thng
hin ti ni chung v mng thng tin di ng ni ring. Kh nng ng dng ca ti
l gip ch cho nhng ngi lm cng tc trong ngnh, l c s l thuyt phn tch
v tin hnh, t hon ton c th tm ra gii php ti u khoa hc nht.
59
7/31/2019 DO an -Khojduy
60/61
Ti u ha mng
Tuy nhin do thi gian thc hin c hn v trnh , kinh nghim cn hn ch
nn trong qu trnh lm n em khng th trnh khi thiu st. Em rt mong c
c nhng kin nh gi, gp ca cc thy, c v cc bn. Hy vong trong tng
lai gn s tip tc c c hi tip tc nghin cu trn h thng thc t.
Em xin chn thnh cm n.
H Ni, thng 6 nm 2012
Sinh vin thc hin
Nguyn Duy Khi
TI LIU THAM KHO
[1] PTS.Nguyn Phm Anh Dng, Thng tin di ng GSM,Nh xut bn bu in,
H Ni 1999.
[2] V c Th, Tnh ton mng thng tin di ng s CELLULAR,Nh xut bn
gio dc, H Ni 1999.
[3] J. Dahlin,Ericssons Multiple Reuse Pattern For DCS 1800, in Mobile
Communications International, Nov., 1996.
[4] Asha K. Mehrotra, GSM System Engineering, Artech House, Inc Boston London
1996.
[5] Phng K thut, Quy trnh o Drive Test trong mng v tuyn, Cng ty ITC, H
Ni 2009
[6] Phng k thut, S tay BTS thit b Alcatel, Cng ty ITC, H Ni, 2009
60
7/31/2019 DO an -Khojduy
61/61
Ti u ha mng
Recommended