Mobilné dátové siete

GSM/GPRS/EDGE/UMTS&

more

Obsah• Sieťová architektúra & protokoly

– GSM, GPRS

• Mobility management

• Vzdušné rozhranie– TDMA/FDMA, základné charakteristiky, EDGE

• UMTS ako evolúcia GSM

architektúra GSM

BSC

BTS

bunka

MSC

HLR

VLR AuC EIR

GMSC PSTN

architektúra GSM/GPRS

BSC

BTS

bunka

MSC

HLR

VLR AuC EIR

GMSC PSTNPCU

SGSN GGSN PDN

Gb

Gn Gi

Packet Control Unit

• Radio resource management– MAC, RLC layer– BSSGP

Serving GPRS Support Node

Main functions:– charging– IP connectivity & routing– mobility management– payload handling– QoS– security– session management– subscriber data management

Gateway GPRS Support Node

Main functions:– routing– tunneling & VPN– security– QoS– charging– session management

Protokolový model prenos používateľských dát

Protokolový model prenos signalizácie

GTP

• used on Gn interface (SGSN-GGSN)• IP based connection (backbone)• GTP-U for user data• GTP-C for control

– create, update, and delete tunnels– path/mobility/location management,

• point-to-point UDP/IP tunnel

SNDCP

• on Gb interface• multiplexing of PDPs (NSAPI)• compression of user data (including IP

header compression)• segmentation/reassembly of data packets

to be passed to/from the LLC layer

LLC

• provides a reliable link between the mobile device and the SGSN for both control and user data

• supports variable length information fields from 140 bytes up to a max of 1520 bytes

• acknowledged/unacknowledged mode

BSSGP

• introduce & provide the required QoS for the user

• routing information between BSS & SGSN• informs the BSC about the radio capability

of the mobile device• flow control

Session/Mobility management

• Routing area concept

• Session management – PDP context

• Mobility states– attach/detach procedure

Routing area

Intra SGSN RAU

Inter SGSN RAU

Mobility states

GPRS attach procedure

GPRS detach procedure

PDP context

• Packet Data Protocol Type (e.g. IPv4)• PDP address (IP address)• QoS• address of GGSN (or APN)

PDP Context Activation Procedure

MS-Initiated PDP Context Deactivation Procedure

GSM air interface

GPRS air interface

Packet Header User data

Information field TailHeaderLLC PDU

USF RLCHeader

RLCInformation BCS ...Radio Blocks

LLC layer

RLC/MAC layer

Physical layer

Multiframe structure, 52 TDMA frames

Network Layer

USF RLCHeader

RLCInformation BCS

NormalBurst

NormalBurst

NormalBurst

NormalBurst

B0 B1 B2 X B3 B4 B5 X B6 B7 B8 X B9 B10 B11 X

~ 1.6 kbytes

≤ 1500 bytes

20-50 bytes

4 × 114 bitsBy EGPRS affected layer

RLC8PSK

Multiframe structure

10

20

30

40

50

60

0

MC

S1

MC

S2

MC

S3

MC

S4

MC

S5

MC

S6

MC

S7

MC

S8

MC

S9

CS1

CS2

CS3

CS4

GMSK modulation 8PSK modulation

8.0

12.014.4

20.0

8.411.2

14.817.6

22.4

29.6

44.8

54.4

59.2kbps

GPRS EGPRS

EDGE - EGPRS

Temporary Block Flow

• The transmission of packets to/from a certain MS is called a TBF

• TFI used for DL multiplexing• USF used for UL multiplexing

UMTS architecture

BSC

BTSBTSBTS

RNC

Node B Node B Node B

MSC SGSN

GGSNGMSC

VLR HLR AuC EIR

PSTN PDN

MS UE

IuB

IuCSIuPS

Basic facts

• new radio access technology– CDMA, 5 MHz FDD, …

• smooth evolution of core network

• new protocol stacks for new interfaces

• some changes in mobility management

Basic principles – code separation

• UMTS uses codes for user separation –users share time and frequency resources

“Hello”“Bonjour”

“Shalom”“Buenos Dias”

“Guten Tag”

Base station

New effects in UMTS Access Network

Cell breathing– The more users are active in a cell, the

smaller the cell radius

• Interference limited system => capacity depends on available RBS power (↑) & user activity (↓)

Air interface

• FDD or TDD, 5 MHz channel

• 3,84 Mchip/s, QPSK

• Phy bitrates: up to 1920 kbps DL, 960 kbps UL

Channel concept

what type of data

how and with which type of characteristics

define the exact physical characteristics

BCCH, PCCH, DCCH, CCCH,DTCH, CTCH, …

BCH, PCH, RACH, FACH,DSCH, HS-DSCH, DCH, …

SCH, CPICH, PDSCH, HS-PDSCH,DPDCH, DPCCH, PRACH, …

new for UMTS, not in GSM/GPRS

UMTS UP protocol model

Protocol model for IuB

TN CP PS UP B CP CS Data UP CS VoiceNAS Application Application

TAFRLP

RLC STCMAC SSCF-UNI SSCF-UNIFP SSCOP SSCOP

AAL2 AAL5 AAL5ATM

MACFP

AAL2

AMR

RLC

ALCAP PDCP BMCRRC NBAP

RN CP

TN CP PS UP B CP CS Data UP CS VoiceNAS Application Application

TAFRLP

RLC STCMAC SSCF-UNI SSCF-UNIFP SSCOP SSCOP

UDP SCTP SCTP UDPIPv4 / IPv6Ethernet

RN CP

AMRRRC NBAP ALCAP PDCP BMC

RLCMACFP

Node B

RNC

Session/Mobility management

• basically the same as for GPRS• the same Routing Area concept• PDP context• new MM states

PMM = Packet Mobility Management

Core network evolution I

GSM/GPRS

UMTS R99

Core network evolution II

UMTS R4

UMTS R99

Core network evolution III

UMTS R5

UMTS R4

UMTS System Architecture Evolution

Gb Iu

GERAN UTRAN

3G2GeRAN

LTENon-3GPP

MME/UPE

SGi

IP networks

S3

S4

S5a

S6 S7

S1

S2a

PCRFHSS

SGSN

3GPPAnchor

SAEAnchor

S5b

IASA

IP access WLAN

ePDG

S2b

Non-3GPP

UMTS – the right model for data?

• NO!– hierarchical– centralized– protocol translations– QoS models differ from IP world

• Solution:– connect every base station directly to Internet– use Mobile IP protocol

Flat all IP architecture

AAA

HAInternal IP LAN

Public Internet

FA

FAFA

FA

Ethe

rnetEthe

rnet

Ethe

rnet Ethe

rnet

All IP – a comparison

• UMTS all IP vs. F-OFDM all IP

F-OFDM LinkF-OFDM MACF-OFDM Phy

IP IP

Ethernet

Base station

NodeB RNC SGSNIP (application)

PDCPRLCMAC

UMTS Phy

IP (application)PDCPRLCMACFP

UDPIP (transport)

Ethernet

IP (application)

UDPIP (transport)

Ethernet

GTU-U2 IP layers=> more overhead

pure IP