Post on 27-Apr-2017
Sisteme de Comunicatii
Mobile (SCMB)
- curs 9 -
Continutul prezentarii
EDGE Principii
Scheme de codare
Parametri QoS
Introducere in 3G Familia IMT 2000
Servicii
WCDMA
Evolutia 2G –> 3G
2+ = GSM Phase 2+
HSCSD = High Speed Circuit Switched
Data
GPRS = General Packet Radio System
EDGE = Enhanced Data for GSM
Evolution
UMTS = Universal Mobile
Telecommunication System
EDGE - caracteristici
Modificarea interfetei radio pastrand TDMA
Se introduce modulatia 8-PSK (3 bit/simbol)
Se combina cu operarea multislot
Variante de EDGE: E-GPRS
E-CSD
Debit maxim teoretic: 384 Kbps Debit mediu: 100 Kbps / User
EDGE – scheme de codare
MCS Modulation Code rate User Rate/TS
1 GMSK .53 8.8 kbps
2 GMSK .66 11.2 kbps
3 GMSK .80 14.8 kbps
4 GMSK 1 17.6 kbps
5 8PSK .37 22.4 kbps
6 8PSK .49 29.6 kbps
7 8PSK .76 44.8 kbps
8 8PSK .92 54.4 kbps
9 8PSK 1 59.2 kbps
EDGE – performante (1)
Debit in functie de raportul semnal / zgomot
0 5 10 15 20 25 30 35 40 45 0
10
20
30
40
50
60
SNR [dB]
thro
ug
hpu
t p
er
tim
eslo
t [k
bp
s]
EDGE – performante (2)
Parametri QoS
DOCUMENTTYPE 1 (1)
TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere
Traffic class ConversationalRT
- guaranteedcapacity- no ARQ
StreamingRT
- guaranteedcapacity - ARQ (MAClevel) - Add. Buffering inapplication
InteractiveNRT
-best effort- ARQ- interactiveWWW, Telnet,- RT controlchannel
BackgroundNRT
-best effort- ARQ- backgrounddownload ofemails,calendarevents, etc.
Delay 100ms, 200ms,400ms
< 1 s 2 s N/A
BER 10-3, 10
-4, 10
-5 10
-5, 10
-6, 10
-7, 10
-
8 < 10
-9 < 10
-9
Max bitrate Guaranteed Guaranteed bitrate isguaranteed, notthe maximum
Notguaranteed
Notguaranteed
Serviceprecedence
High, medium, low High, medium,low
High, medium,low
High, medium,low
3G – Origini, motivatie
Previziuni 2015: 3 miliarde abonati mobili, venituri estimate la 350 miliarde $
Motivatie: creste utilizarea serviciilor mobile de date
Problema: incompatibilitatea sistemelor 2G: PDC (Personal Digital Cellular), PHS (Personal
Handyphone System) – Japonia
AMPS (Advanced Mobile Phone Service), IS-136 (D-AMPS), IS-95 (cdmaOne) – America, Asia
GSM (Global System for Mobile Communications) – Europa, Asia, America
IMT 2000
Necesitati: un standard unic
Problema: interesele economice diverse!
ITU (International Telecommunication Union) propune
familia de standarde IMT 2000 (International Mobile
Telecommunications) - un membru al familiei:
Ofera roaming altor membri
Serviciile respecta niste capabilitati standard
Capabilitati IMT 2000
Acces wireless mobil si fix prin retele diverse la debite 144K, 384K, 2M
Roaming global
Interoperare cu 2G
Operare in mod pachet sau circuit
Negocierea QoS
VHE (Virtual Home Environment) – portabilitate servicii/preferinte peste retele/terminale diverse
Interfete IMT 2000
UIM (User Identity Module) – MT
MT – RAN (Radio Access Network), bazata pe WCDMA, TDD/FDD
RAN – CN (Core Network)
NNI (Network to Network Interface), intre diferite CN
Sisteme 3G
Tendinta 1, 3GPP (3rd Generation Partnership
Project), GSM -> UMTS
Tendinta 2, 3GPP2, IS-95 -> Cdma 2000
Benzi rezervate IMT 2000:
1885-2025 MHz, 2110-2200 MHz
806-960 MHz, 1710-1885 MHz, 2500-2690 MHz
Servicii 3G - domenii
UMTS - Acoperire
UMTS – Retea acces si nucleu
CORE
(IP, ATM, SDH, DWDM, etc.)
BRAN
(Broadband
Radio Access
Network)
SRAN
(Satellite
Radio Access
Network)
UTRAN
(Univ. Terrestrial
Radio Access
Network)
802.11 WCDMA
Arhitectura UMTS – coexistenta cu
2G
UMTS Release 2000 EDGE/IPT
Mobile
NEW !
WCDMA/IPT
Mobile
EDGE (GSM) BSS
BS
BS
BS
BS
BSC
BSC
Abis
WCDMA UTRAN
BS
BS
BS
BS
RNC
RNC Iur
Iub
GGSN
SCP HLR
3G-SGSN Iu
CSCF MGCF
SGW
MGW
PSTN/ ISDN
Internet
Multimedia Service Control (IPTelephony)
Packet Core (GPRS) with real time services
NEW ! NEW !
IP transport option for SS7
GMSC MSC/VLR
Circuit Core
Arhitectura UMTS
Server
Server
ETC ETC
ETC ETC
GSW
GSW
GSW
GSW
ETC
ETC
ETC ETC
CLA
ETC ETC
PDE
DX 200
ETC ETC
ETC ETC
GSW
GSW
GSW
GSW
ETC
ETC
ETC ETC
CLA
ETC ETC
PDE
DX 200
PSTN/N-ISDN
Data Network (Internet)
SS7 Network
Inter-PLMN Backbone Network
Inter-PLMN Backbone Network
Node B
RNC
Iur Iu MAP
Iu
3G-GGSN
3G-SGSN
Gn
IP Gp Firewall
Border Gateway Gn
3G-MSC
CS Domain
PS Domain
EIR
HLR/AuC
LAN
LAN
Firewall
Router
Router
Corporate 2
Corporate 1
Iub
Gi
UTRA - Reteaua de acces radio
terestra 3G
UTRA – alocare spectru
1980 2010 2025 2110 2170 2200 MHz
1900
TDD
UL/DL
TDD
UL/DL
1920
FDD / UL
W-CDMA MSS
UL
FDD / DL
W-CDMA MSS
DL
MSS – Mobile Satellite System
UTRA: FDD versus TDD
time
frequ
ency
• Frequency division duplex (FDD)
• (Full duplex in analog systems)
time
frequ
ency • Time division duplex (TDD)
• (Half duplex in analog systems)
Caracteristici WCDMA
FDD/TDD
UTRA FDD Technical summary Frequency band:1920 MHz -1980 MHz and 2110 MHz - 2170 MHz (Frequency Division Duplex) UL and DL
Minimum frequency band required: ~ 2x5MHz Frequency re-use: 1 Carrier Spacing: 4.4MHz - 5.2 MHz Maximum number of (voice) channels on 2x5MHz: ~196 (spreading factor 256 UL, AMR 7.95kbps) / ~98 (spreading factor 128 UL, AMR 12.2kbps) Voice coding: AMR codecs (4.75 kHz - 12.2 kHz, GSM EFR=12.2 kHz) and SID (1.8 kHz) Channel coding: Convolutional coding, Turbo code for high rate data Duplexer needed (190MHz separation), Asymmetric connection supported Tx/Rx isolation: MS: 55dB, BS: 80dB Receiver: Rake Receiver sensitivity: Node B: -121dBm, Mobile -117dBm at BER of 10-3 Data type: Packet and circuit switch Modulation: QPSK Pulse shaping: Root raised cosine, roll-off = 0.22 Chip rate: 3.84 Mcps Channel raster: 200 kHz Maximum user data rate (Physical channel): ~ 2.3Mbps (spreading factor 4, parallel codes (3 DL / 6 UL), 1/2 rate coding), but interference limited. Maximum user data rate (Offered): 384 kbps (year 2002), higher rates ( ~ 2 Mbps) in the near future. HSPDA will offer data speeds up to 8-10 Mbps (and 20 Mbps for MIMO systems) Channel bit rate: 5.76Mbps Frame length: 10ms (38400 chips) Number of slots / frame: 15 Number of chips / slot: 2560 chips Handovers: Soft, Softer, (interfrequency: Hard) Power control period: Time slot = 1500 Hz rate Power control step size: 0.5, 1, 1.5 and 2 dB (Variable) Power control range: UL 80dB, DL 30dB Mobile peak power: Power class 1: +33 dBm (+1dB/-3dB) = 2W; class 2 +27 dBm, class 3 +24 dBm, class 4 +21 dBm Number of unique base station identification codes: 512 / frequency Physical layer spreading factors: 4 ... 256 UL, 4 ... 512 DL
UTRA TDD Technical Summary Frequency band:1900 MHz -1920 MHz and 2010 MHz - 2025 MHz (Time Division Duplex) Unpaired, channel spacing is 5 MHz and raster is 200 kHz. Tx and Rx are not separated in frequency, but by guard period. Minimum frequency band required: ~ 5MHz, ~ 1.6MHz with 1.28 Mcps Frequency re-use: 1 Voice coding: AMR (and GSM EFR) codec Channel coding: Convolutional coding, Turbo code for high rate data TDMA frame consist of 15 timeslots Each time slot can be transmit of receive Duplexer not needed Asymmetric connection supported Data by packet and circuit switch QPSK modulation Receiver: Joint Detection, (mobile: Rake) Chip rate: 3.84 Mcps or 1.28 Mcps Channel raster: 200 kHz Maximum RF ch bit rate (kbps): ~ 3.3Mbps (1/2 rate coding, spreading factor 1, 15 timeslots, ex overheads), but interference limited Frame length: 10ms Number of slots / frame: 15 Handovers: Hard Power control period: 100 Hz or 200 Hz UL, ~ 800 Hz DL Power control step size: 1, 2, 3 dB (Variable) Power control range: UL 65dB, DL 30dB Mobile peak power: Power class 1: +33 dBm (+1dB/-3dB) = 2W; class 2 +27 dBm, class 3 +24 dBm, class 4 +21 dBm Number of unique base station identification codes: 512/frequency Physical layer spreading factors: 1, 2, 4, 8, 16
CDMA, WCDMA
Tehnica de acces multiplu (mai multe MS utilizeaza
resurse radio in comun), cu multiplexare in cod
W – “wide band”, sugereaza largirea mai mare a benzii
CDMA
Un anumit numar de semnale CDMA sunt emise in
aceeasi banda
Un receptor CDMA extrage semnalul dorit folosind acelasi cod
utilizat la emisie
Restul semnalelor sunt eliminate datorita corelatiei slabe intre
codurile diferite utilizate le emisie (coduri ortogonale)
WCDMA - principiu
WCDMA – Coduri OVSF (Orthogonal
Variable Spreading Factor)
Generarea codurilor ortogonale – arbore de coduri, nivel
SF (spreading factor - n) maxim 512
Exemple utilizare:
SF = 4 -> date la 2Mbps,
SF = 128 -> voce la 12,2Kbps
SF = 512 -> semnalizari, SMS la 1,7 Kbps
Proprietatile de corelatie ale
codurilor CDMA
Coduri - secvente binare de lungime identica
Intercorelatia RS,T : masoara gradul de asemanare intre 2
secvente binare S, T (nr. asemanari – nr. diferente)
Pentru codurile CDMA cerintele sunt:
Autocorelatia RS(i) este maxima pentru i = 0 si de valoare mica
sau negativa in rest (0 pentru familii de coduri ortogonale)
Intercorelatia intre 2 coduri diferite este de valoare mica sau
negativa (0 pentru familii de coduri ortogonale)
1
0
, )1()(N
j
TS
TSjiiiR
Utilizarea codurilor OVSF
Semnalul de date este codat NRZ (1:1, 0:-1)
Codul de adaptare la canal (channelisation code) are o
perioada mai mica -> creste debitul/banda (chip rate)
Al doilea nivel de codare (scrambling code) asigura un
caracter pseudo-aleator
Se utilizeaza secvente de lungimea unui cadru radio (10
ms – 38400 chips)
WCDMA – imprastierea
spectrului
WCDMA – lantul de transmisie,
interferente
CDMA versus TDMA
Emitator CDMA – schema de
principiu
WCDMA – spreading/despreading
WCDMA – receptia in conditii de
“zgomot” provenit de la alte MS
Bibliografie
“Comunicatii mobile. Evolutia spre 3G”, Autor:Sorina Zahan, Editura:Albastra
Gsm, Gprs and Edge Performance: Evolution Toward 3G/Umts de Timo Halonen, Javier Romero Garcia, Juan Melero