Tong Quan GSM-Cau Truc BTS

8/4/2019 Tong Quan GSM-Cau Truc BTS

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PHAN ITONG QUAN VE HE THONG GSM

1. GII THIEU CHUNG VE HE THONG GSM

He thong thong tin di ong GSM 900 la he thong thong tin di ong dung bang tan xungquanh bang tang 900MHz( 890 960MHz) c chia thanh hai day tang: Day tan t 890 915MHz dung cho ng len t MS en BTS (Uplink) Day tan t 935 960MHz dung cho ng xuong t BTS en MS (Downlink)

Khoang cach gia cac song mang trong he thong GSM la 200KHz ma he thong GSM 900co 2 bang tang rong 25MHz bao gom 25MHz/200KHz=125 kenh. Trong o kenh 0 la day

bao ve con cac kenh 1 124 c goi la kenh tan so vo tuyen tuyet oi. Viet Nam bangtang GSM900 c cap cho 3 nha khai thac vi s phan chia nh sau:

Ra dio Network Pla nning

Fre que ncy P lanning

Vietels GSM Frequency Bands:

Width: 8.2 MHz

Number of channels: 39 + 3 guard bands (from 42 to 83)

Uplink: 898.4 MHz to 906.6 MHz

Downlink: 943.4 MHz to 951.6 MHz

1 41 43 54 84 12456 81

12 BCCH 26 TCH

V I E T E L

42 55 83

82

Joker

Operator AOperator B

Vinaphone Mobilephone

Ra dio Network Pla nning

Fre que ncy P lanning

Vietels GSM Frequency Bands:

Width: 8.2 MHz

Number of channels: 39 + 3 guard bands (from 42 to 83)

Uplink: 898.4 MHz to 906.6 MHz

Downlink: 943.4 MHz to 951.6 MHz

1 41 43 54 84 12456 81

12 BCCH 26 TCH

V I E T E L

42 55 83

82

Joker

Operator AOperator B

Vinaphone Mobilephone


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2. CAU TRUC HE THONG CON CHUYEN MACH: (SSS)

BSS

BSC

BTS

MS

OSS

Switching System

Information transmission

Call connections andinformation transmission

Base Station System

SS

MSC/VLR

EIRGMSC

DTI

AUC

HLR

SMS-GMSC

SMS-IWMSC

Giao tip v tuyn Um

Abis

A

CCu tru trc hc h ththng thng thngng tintin

GSM/DCSGSM/DCS--PLMNPLMN

2.1 MSC (Mobile Switching Centre): Trung tam chuyen mach dch vu di ong

MSC chu trach nhiem ve viec thiet lap s ket noi cac kenh lu thong:+ Ti tram goc BSS+ Ti he thong chuyen mach di ong MSC khac+ Va ti nhng mang chuyen mach khac (chang han ti PSTN, PSDN)MSC con thc hien chc nang quan ly nhng vung nh v, x ly nhng dch vu c s,dch vu bo sung, thc hien qua trnh tnh cc.

2.2 HLR(Home Location Register):

Bo ghi nh v thng tru: no quan ly toan bo d lieu thue bao cua vung phu, cua mang.

HLR la mot c s d lieu ni ma nhng thue bao di ong c tao ra, c tach ra,c cam hoac c xoa i bi ngi ieu hanh.

2.3 VLR(Visitor Location Register): (c ket hp vi MSC)

Trong thi gian MS cap nhat v tr, d lieu thue bao c chuyen t HLR ti VLR hientai. D lieu nay c lu tr trong VLR trong suot thi gian ma MS di chuyen trongvung nay. VLR se cung cap d lieu cho thue bao bat ky luc nao no can cho viec x lymot cuoc goi. Neu mot thue bao di ong di chuyen en vung phuc vu VLR khac th motcap nhat v tr xay ra lan na, VLR mi yeu cau d lieu thue bao t HLR chu trachnhiem ve thue bao di ong.


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2.4 AuC(Authencation Centre) va EIR(Equipment Identification register):

Mot thue bao muon truy cap mang, VLR kiem tra Sim card cua no co c chap nhanhay khong, ngha la no thc hien mot s nhan thc. VLR s dung nhng thong so nhanthc c goi la nhng bo ba, no c tao ra mot cach lien tuc va rieng biet cho moithue bao di ong c cung cap bi trung tam nhan thc AC. AC c ket hp viHLR.EIR kiem tra tnh hp le cua thue bao da tren yeu cau ac tnh thiet b di ong quoc teIMEI t MS sau o gi no ti bo ghi nhan dang thiet b EIR. Trong EIR, IMEI cua toanbo thiet b di ong c s dung th phai c phan chia thanh ba danh sach.+ Danh sach mau trang: cha thiet b di ong c chap nhan.+ Danh sach mau xam: cha thiet b di ong c theo doi.+ Danh sach mau en: cha thiet b di ong khong c chap nhan.EIR kiem tra IMEI co thch hp vao mot trong ba danh sach hay khong va chuyen ketqua ti MSC.

3. HE THONG CON VO TUYEN:

He thong con vo tuyen bao gom:+ Thiet b di ong ME+ He thong tram goc BSS

He thong tram goc BSS bao gom:- Tram thu phat goc BTS- Bo ieu khien tram goc BSC- Bo chuyen ma va chuyen oi toc o TRAU

3.1 BSC:

Bo ieu khien tram goc BSC cung cap nhng chc nang thong minh ieu khien moihoat ong cua he thong tram goc (BSS). Mot BSC co the ieu khien nhieu BTS. Nophan phoi s ket noi cac kenh lu lng (Traffic channel) t he thong chuyen mach ti

cac cell vo tuyen BTS, ngoai ra no con thc hien qua trnh chuyen giao cung vi MSC.3.2 BTS:

BTS c thiet lap tai tam cua moi te bao, no thong tin en cac MS thong qua giaodien vo tuyen Um, ngha la no cung cap nhng ket noi vo tuyen gia MS va BTS.BTS c xac nh bang cac thong so mo ta nh kha nang truyen dan, ten cua cell,bang tan vo tuyen

3.3 He thong chuyen ma va chuyen oi toc o TRAU:

TRAU gom hai khoi chc nang:


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Thc hien viec chuyen oi luong d lieu 64kb/s (tieng noi, d lieu) t MSCthanh luong d lieu co toc o tng oi thap tng ng vi giao dien vo tuyen

16kb/s. Thc hien qua trnh tach ghep luong

4. HE THONG OSS:

Tat ca moi s hoat ong, s kiem tra va s bao tr cho tat ca nhng thanh phan mangSSS, BSS (BSC, BTS, TRAU) co the c thc hien trung tam OMS, goi la trung tamvan hanh va bao dng.He thong OMS bao gom mot hoac nhieu OMC (OMC R, OMC S). OMC c lien

ket vi nhng phan t SSS va BSS thong qua mot mang d lieu goi X25.

5. HE THONG GPRS:

+ oi vi he thong GSM toc o truyen d lieu c gii han la 9,6kbit/s, vi hnh thcchuyen mach mach.+ He thong GPRS (General packet radio sevice) se la giai phap e ap ng oi hoi choviec truyen d lieu toc o cao da tren mang chuyen mach goi. Toc o d lieu co thelen en 160kbit/s.Khi toc o d lieu tang len th ta co the tch hp c nhieu dch vu so tren mang.Luc nay tren mang PLMN ton tai 2 he thong song song:- He thong chuyen mach mach cho thoai.- He thong chuyen mach goi cho d lieu.Thanh phan cua he thong GPRS. MFS: Multi BSS fast packet sever- Thc hien nhng chc nang ieu khien goi.- Quan ly tai nguyen vo tuyen cho GPRS cho mot vai BSS.- Quan ly giao dien vi mang GPRS. SGSN: serving GPRS support node.- nh tuyen goi MS- ieu khien tham nhap, ieu khien bao ve- Giao dien vi HLR- VLR cho GPRS GGSN: Gateway GPRS support node- La phan cua mang GPRS- nh tuyen IP, link ti mot hoac vai mang d lieu- Lam viec vi mang chuyen mach goi ben ngoai


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PHAN 2

TONG QUAN VE HE THONG BTS

1. GII THIEU CHUNG VE BTS

1.1 Khai niem ve BTSBTS la mot thiet b dung e phat tn hieu ra moi trng vo tuyen en cac may d ongva thu tn heu t cac may di ong cung thong qua moi trng vo tuyen. No thong tinen cac MS thong qua giao dien vo tuyen Um va ket noi vi bo ieu khien tram gocBSC(Base Station Controller) thong qua giao dien Abis.

1.2 V tr cua BTS trong he thong GSM

CAU TRUC MANG G SM

Radio tower

Radio tower

BSC

TC

MFS

SG N

HLR

BTS

BTS

GGSN

PSTN

INTERNET

IP GPRS

BACKBONE

BSS

OMC-R

MSC

S o tren mo ta v tr cua BTS trong he thong mang GSM. Cac BTS c at khap nitrong vung co ke hoach phu song va no c ket noi ti bo ieu khien tram goc BSC(Base Station Controller). Ngoai ra v tr cua BTS con phu thuoc vao cau hnh ket noiti BSC, chang han nh co cac cau hnh sau:-Sectorised configuration-Multipion configuration-Chain configuration-Star configuration


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1.3 Phan loai BTS

Thiet BTS b ma cong ty ta s dung khu vc pha nam la loai thiet b A9100 cua hangALCATEL no gom co 2 loai chnh o la:1.3.1.MBI:La loai BTS dung trong phong kn, trong loai BTS nay lai chia thanh 2 dang, o ladang nho MBI3, no ch gom co 3 subrack vi trong lng ln nhat la 150kg; loai conlai la MBI5 no gom co 5 subrack vi trong lng toi a la 270kg. Kch thc va hnhdang c c mo ta nh sau:

Ngoai nhng subrack chnh dung e lap at nhng thiet b chnh cua BTS th no con

co nhng khe nho xen gia nhng subrack dung e lap at cac quat e lam mat chothiet b cua BTS va mot khu vc dung cho viec au noi cap tn hieu va cap canh baocho BTS...

1.3.2. MBO:La loai BTS co the at ngoai tri va cung giong nh BTS MBI no cung co 2 dangla MBO1 vi trong lng ln nhat la 255kg va MBO2 la dang m rong cua MBO1vi trong lng toi a la 425kg. Kch thc va hnh dang c mo ta mo ta nh sau:


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Cung tng t nh MBI, MBO cung co nhng tang quat va khu vc dung e au noicap tn hieu va cap canh bao. Ngoai ra no con co them cac khu vc dung e lap atac qui va nhng khu vc dung cho viec lap at cac thiet b truyen dan.

2. CAU TRUC CUA HE THONG BTS2.1 Cau truc chung cua he thong BTS

KIEN TRU C CAC KHO I CHC NA N G CU A H ETHONG BTS

C LOC K

T

R

A

N

S

O M U

SU M

TR E ANAbis

BTS-TE


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He thong BTS gom co cac khoi chc nang sau :+ SUMA

+ TRE+ AN

2.2 Cau truc va chc nang cua cac khoi trong he thong BTS2.2.1. Khoi SUMA

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

- XCLK (External clock): la ong ho ben ngoai- CLKI: la he thong ong ho chu c phan phoi ti TRE vaAN- MMI: thong qua serial link e ket noi ti BTS Terminal, thc hien quan ly

loi, tac ong trc tiep en he thong bang mot so lenh n gian.- XBCB: External BTS control bus

- BCB: BTS control bus (trang thai, cau hnh, canh bao)- BSII: mang thong tin TCH, RSL, OML,IOM-CONF- SUMA: la khoi trung tam cua mot BTS, mot BTS ch co mot SUMA bat ke so

sector va TRX la bao nhieu

Nhng chc nang SUMA:- Quan ly link truyen dan Abis (len en 2 giao dien Abis)- Tao xung ong ho cho tat ca cac modul BTS, cac ong ho nay co the c ong

bo t mot ong ho tham chieu ben ngoai: Abis link, GPS, BTS khac, co the c

tao ra trong kieu xung roi bi mot bo phat tan so ben trong.


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- Thc hien chng nang van hanh va bao dng cho BTS- Quan ly ghep cac d lieu TCH, RSL, OML, QMUX

- ieu khien chc nang AC/DC khi chung c tch hp ben trong BTS- ieu khien nguon (dung lng, ien ap, nhiet o)- Thiet lap ien ap va dong cho viec nap pin.

2.2.2.Khoi TREKIEN TRUC C S CUA TRE

TRED

TREA

TREPPSI

RFI

CLKI

BSII

BCB PSWITCH

LEDS

DEBUG

RCD CUI I2CA

- RFI: giao dien nay c s dung e loop vong- PSI: giao dien nay e cung cap nguon- PRI: Power Supply & Remote Interface c s dung e phan phoi nguon.- CUI: giao dien nay c s dung e tham nhap trc tiep en cac thanh phan khac

nhau cua TRE (truyen d lieu ieu khien, cau hnh gia TRED va TREA)- CUI cung mang nhng tn hieu ong ho tham chieu en cac thanh phan cua TRE- I2CE: giao dien nay c s dung e TRED nhan d lieu c lu tr tren TREA- RCD: giao dien nay c s dung e thong bao viec kiem tra tn hieu DC t giao

dien RFI (TREA) en TRED- ADR (Addressing)- DEBUG: giao dien nay c s dung trong suot qua trnh phat trien e kiem tra

cac TRE (t MMI)Modul TRE thc hien nhng chc nang Telecom


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2.2.2.1.Chc Nang Cac Khoi Trong TREa. TRED:

He thong TRED chieu trach nhiem ve phan so cua TR:+ X ly ieu khien va bao hieu, no chu trach nhiem quan ly cac chc nangO&M cua TRE+ Ghep kenh, nhay tan, mat ma va giai mat ma+ Ma hoa (DEC)+ Giai ieu che (DEM)+ Ma hoa va phat (ENCT)+ au cuoi BCB

b. TREA:+ ieu che+ ieu khien va bien oi cao tan phan phat (TXRFCC)+ Tong hp phan phat (TXSYN)+ Bien oi trung tan phan thu (RXIF)+ Tong hp phan thu (RXSYN)+ Giai ieu che trung tan (ISD)+ RF loop+ TRE PA board bao gom bo khuech ai cong suat, no am nhiem khuech ai

cong suat tn hieu cao tan bi TXRFCC. No cung cung cap VSWR va kiem tranguon, RF loopc. TREP: Cung cap nguon cho TRE (DC/DC)

2.2.3.Khoi ANCCOMBINING MO DE

DuplexerF ilt er F ilte r

LN A

Spliter

DuplexerF ilt er F ilte r

LN A

Spliter

Spliter SpliterSpliterSpliterW BC W BC

A N TA A N TB

TRE 1

T X R X R Xd

TRE 2

T X R X R Xd

TRE 3

R Xd R X T X

TRE 4

R Xd R X T XBridgeBridge


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ANC ket noi 4 may phat en 2 antenna.

Phan phoi tn hieu nhan c t moi antenna en 4 may thu (thu thng va thu phantap)Modul nay bao gom 2 cau truc giong nhau, moi cau truc bao gom:

+Antenna: no co chc nang la phat song ra moi trng vo tuyen va thu songt may di ong phat en.+ Mot khoi duplexer: dung e ket hp hai hng phat va thu tren cung motantenna.+ Mot khoi LNA: khoi nay co chc nang khuech ai tn hieu ma antenna thuc len mc u ln e cho TRE co the x l c.

+ Hai khoi Spliter: khoi nay co chc nang tach tn hieu thu cua 2 TRE.+ WBC: bo nay co chc nang ket hp hai ng phat lai vi nhau e i trencung mot ng en bo duplexer. Thc te ta ch dung bo nay khi ta dung hn2 TRX tren cung mot sector, neu khong dung ket hp th ta phai g cau ra vaket noi trc tiep vi duplexer ma khong thong qua bo WBC.

Khi qua bo ANC tn hieu se b suy hao la 3.3dBm

3. NGUYEN LY HOAT ONG CUA BTS

3.1. Ket noi cac khoi chc nang trong he thong BTSGiao tiep ben trong BTS c thc hien thong qua cac bus BCB va BSII.

BSII 1

BSII 2

BT STERM

Abis

KET NOI BEN TRON G

OM U

TRANS&CLOCK

TR E

AN x

AN y

FACB

AC/DC&BATTEIES

ISL

ISL

ISL

ISL

ISL

TRE FW/SWO&M/TELECOM

ANxFW

ISLpilot

EBCB

BS C

OM L/IOM /IOM-CONF

TCH/RSL


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3.1.2. BCB(Base Station Control Bus):BCB: Bus ieu khien BTS dc ket noi den tat ca cac module trong BTS.

No c s dung e trao oi thong tin gia SUMA va cac module khac. Bus nay chs dung cho muc ch van hanh va bao dng.Luong thong tinBus BCB c xac lap hai che o o la master bus hay la slave bus. Master cgoi la pilot, slave c goi la terminal. Mot dung cu ac biet ben ngoai c ket noien XBCB co the c s dung nh la mot pilot.Cho moi module, viec them vao hay lay ra c kiem tra bi viec quet cac bus ieukhien.Viec mat bat c ac tnh nao c cung cap bi BCB th khong gay ra loi trong qua

trnh hoat ong cua BTS nh la: canh bao, truy nhap remote inventoryThong tin ve ban kiem ke module co the truy nhap tham ch khi module switch off.Nhng ma SUMA phai c switch on.

3.1.2. BSII (Base Station Internal Interface):BSII la giao dien chnh ben trong BTS

Luong thong tinBSII c s dung e mang cac loai thong tin sau: TCH RSL OML cho SUM_OMU Cac bao hieu ben trong: phat quang ba t SUM_OMU en cac thc the c ket

noi en BSII cac thong tin IOM_CONF(thong tin ve cau hnh ), nhng thongiep O&M ben trong gia OMU va TRE/Anx/TRANS&CLOCK, nhng thongiep cho kiem tra.

3.2 Nguyen ly hoat ong cua BTSNguyen ly hoat ong cua BTS da tren qua trnh x ly cac tn hieu ma no nhan c

t may di ong va t BSC.3.2.1.Tn Hieu T BSC Gi enTn hieu t BSC a ti BTS thong qua giao dien Abis tren ng truyen PCM gomco cac tn hieu sau: -tn hieu thoai TCH (traffic channel) -tn hieu bao hieu RSL (radio signalling link) -tn hieu van hanh bao dng OML (operation maintenance link) -tn hieu truyen dan QmuxCac tn hieu nay c phan bo tren khung PCM nh sau:


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TS0

TS31

OML

RSL

SYN

TCH TCH

TCH

TCH TCH

TCHTCHTCH

Qmux

CAU TRUC KHUNG PCM TREN GIAO DIEN ABIS

Trong cau truc khung PCM th khe thi gian TS0 c s dung cho muc chong bo.

TS1 dc s dung e truyen tn hieu Qmux. Cac khe thi gian con lai c s dung e truyen d lieu TCH, tn hieubao

hieuvo tuyen va tn hieu van hanh bao dng( RSL/OML).

Cac khe thi gian trong khung PCM c chia thanh 4 nibble moi nibble 16Kbpsc s dung cho mot kenh lu lng TCH. Trong khung PCM giao dien Abis th mot RSL chiem toan bo mot khe thi gian

trong khung va so RSL phu thuoc vao so TRX ma mot BTS co. Tc la so lngcua RSL se bang so TRX.

Trong khung PCM con co tn hieu OML tn hieu nay s dung trong qua trnh khaithac va bao dng. Mot OML se chiem mot TS trong khung PCM va so lngng OML se phu thuoc vao so BTS. Moi OML se phuc vu ch cho mot BTS.

Ngoai ra trong BTS cai tien cung cap ghep kenh thong ke. Tc la s dung khe

thi gian 64Kbps s dung truyen cho 4RSL va 1OML, tc la thc hien qua trnhghep 4 RSL vi 1OML. Cung cap ng truyen Qmux qua giao dien abis:

o Trong qua trnh hoat ong ngoai nhng thong tin bao hieu va thong tin ve vanhanh va bao dng th BTS cung can c ieu khien bi BSC. Qua trnhieu khien nay c thc hien bi khoi TSC cua BSC. Lenh ieu khien nayc a vao khung thi gian PCM khe thi gian TS1. Tn hieu nay chiem 1nibble 16Kbps. Thong qua giao dien Abis no se gii tn hieu ieu khien enkhoi TRANS.


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Cac tn hieu nay au tien c a en khoi SUMA va ket cuoi tai phan truyen dan

cua khoi nay, sau o no a en cac khoi chc nang khac e s ly nh sau: Tn hieu Qmux c ket cuoi tai phan truyen dan, e thc hien qua trnh ieu

khien truyen dan. Cac tn hieu ve van hanh bao dng th ket cuoi tai khoi OMU, khoi nhan

thong tin O&M, x ly va a ra cac lenh lien quan en qua trnh van hanhbao dng.

Cac tn hieu ve lu lng va bao hieu se c a en khoi TRE ay sethc hien qua trnh x ly thoai va sau o a en ANC roi ti antenna roiphat ra moi trng vo tuyen.

3.2.2. Tn Hieu Thu T May Di ong MS (Mobile Station)

Tn hieu thu c t MS qua antenna cua BTS va sau o c truyen xuong khoiAnc, khoi nay se loc, khuech ai tap am thap(LNA) va chia cac tn hieu thu(spliters), sau khi c x ly khoi Anc tn hieu tiep tuc c a en khoi th haio la khoi TRE, ay la khoi chu trach nhiem chu yeu ve qua trnh x ly thoai nh

la giai ieu che, giai nh dang cum, giai ma hoa kenh va giai ma hoa thoai. Tnhieu sau o c a en khoi SUMA tai ay no thc hien qua trnh ghep cac tnhieu cac tn hieu lai tren khung PCM, qua trnh nay c thc hien tai phan truyendan(transmission) sau o qua giao dien Abis se gi en BSC.

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Tong Quan GSM-Cau Truc BTS