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