Technologie komunikacji bezprzewodowej” „GPRS and radio ...

Projekt współfinansowany przez Unię Europejskąw ramach Europejskiego Funduszu Społecznego

Technologie komunikacji bezprzewodowej 1

„Technologie komunikacji bezprzewodowej”

„GPRS and radio optimisation”

Prezentacja jest współfinansowana przez Unię Europejską w ramach

Europejskiego Funduszu Społecznego w projekcie pt.

„Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej -zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do

zatrudniania osób niepełnosprawnych”Prezentacja dystrybuowana jest bezpłatnie

Politechnika ŁŁŁŁódzka, ul. ŻŻŻŻeromskiego 116, 90-924 ŁŁŁŁódźźźź, tel. (042) 631 28 83www.kapitalludzki.p.lodz.pl



AgendaAgenda

• Packet transmission GPRS/EDGE

network and transmission channels

• Coverage optimisation problem

• Main performance indicators and

optimization radio tasks



E-mail

File Transfer

Video

WWW Access

Telemetry

Notification

Point of Sale

100 1K 10K 100K

Bandwidth

(bps)

Burstiness

BurstyBursty communicationcommunication



• Efficient use of scarce radio resources

• A flexible service, with volume-based (or session duration-based) billing

• Fast set-up/access time

• Efficient transport of packets in the GSM network

• Simultaneous GSM and GPRS, co-existence without disturbance

• Connectivity to other external packet data networks, using the IP

GPRS GPRS AdvantagesAdvantages



bitrate

Time

GSM HSCSD services up to 57.6 kbps

GSM GPRS services up to 171.2 kbps

UMTS

GSM CS data services up to 9.6 kbps

91/92 98 99/00 02

EDGE services up to 512 kbps

GPRS GPRS EvolutionEvolution



GPRS GPRS LogicalLogical ViewView

MSC/MSC Server

Gr

Gn

OtherPLMN

Gp

Gi

IPNetworkHLR

HLR

FNRFNR

H

Signaling

Signaling and TrafficAUC Authentication Center

BSC Base Station Controller

BTS Base Transceiver Station

EIR Equipment Identity Register

FNR Flexible Number Register

GGSN Gateway GPRS Support Node

MSC Mobile Switching Center

PCU Packet Control Unit

RNC Radio Network Controller

SCP Service Control Point

SGSN Serving GPRS Support Node

SMS Short Message Service

SCPGd

Ge

Gf

BTS BSCA bis

GSM BSS

EIREIR

Gs

Gb

AUC

O&M

Gom Gom

Gp

SGSN/GGSN

SGSN

Gn Gn

PCU

SGSN

SMS

GGSN



BTS

BTS

PSTNPSTN

ISDNISDN

PLMNPLMN

INTERNETINTERNET

BSC

BTS

TRCMGW

HSS

BSC/TRC

UTRANUTRAN

MGW

MSS MSS

GGSN

MC EIR

SGSN

•New nodes: SGSN and GGSN

•New interfaces: Gb (BSC), Gs (MSC), Gr (HLR)

•New radio channels

•Packet switching mode

•Signalling plane for data transmission

•Different radio channel mapping

GPRS GPRS ArchitectureArchitecture



•Forwards incoming/outgoing IP packets to MS

•Provides IP packet routing to PDN destination

•Ciphering and authentication

•Data session management

•Logical link management to MS

•Mobility management

•Connection to HLR, MSC, BSC, GGSN

•Output of billing data

•Geographical SGSN service area

INTERNETINTERNET GGSN BSC/TRC BTSSGSN

SGSN SGSN –– ServingServing GPRS GPRS SupportSupport NodeNode



•Provides interface toward external PDN

•Provides access functionality with ISP (e.g. DNS or RADIUS)

•Manages GPRS session

•Provides communication setup toward external PDN (e.g. MAC address)

•Associates destination user with correct SGSN

•Provides output of billing data

•From outer – works like packet router

INTERNETINTERNET GGSN BSC/TRC BTSSGSN

GGSN GGSN –– Gateway GPRS Support NodeGateway GPRS Support Node



•Class A:

• It supports simultaneous circuit-switched and packet-switched traffic.

•Class B:

• It supports circuit-switched or packet-switched traffic, but does not maintain both kinds of traffic simultaneously.

•Class C:

• It works either as a packet-switched or circuit-switched terminal.

GPRS Mobile TerminalGPRS Mobile Terminal



PACCH

PTCCH/U

Packet Timing advance Control Channel (UL)

Packet Dedicated Control Channel

Packet Traffic Channel

PDTCH

Packet Data Traffic Channel

Packet Common Control Channel

PPCH

Packet Paging Channel (DL)

Packet Random Access Channel (UL)

PRACH

PAGCH

Packet Access Grant Channel (DL)

PNCH

Packet Notification Channel (DL)

PBCCH

Packet Broadcast Control Channel Logical

Channels

Traffic

PTCCH/D

Packet Timing advance Control Channel (DL)

PDCCH

Packet AssociatedControl Channel

(UL/DL)

PCCCH

LogicalLogical channelschannels inin GPRSGPRS



•Dedicated PDCH

–All resources preconfigured and allocated

–Radio TCH

–Gb signalling link

–Abis link TS

•Semidedicated PDCH

–Some resources preconfigured

–Dedicated radio TCH

–On demand Gb signalling link

–On demand (or dedicated) Abis link TS

•On-demand PDCH

–All resources allocated on demand

–Radio TCH

–Gb signalling link

–Abis link TS

GPRS GPRS –– PacketPacket Data Data ChannelsChannels



User dataPH

FH FSCInfo

segment segment

segment segment

FH BCSdata

Physical

RLC/MAC

LLC

SNDCP

ApplicationIP

Burst

20 m sec

Burst Burst Burst 114bits

Encoding and puncture456bits

segment

BSS down to MS

SGSN

Application (server) down to SGSN

Radio Radio PacketPacket SegmentationSegmentation



• Enhanced Data rates for GSM Evolution

• GPRS + EDGE = EGPRS

I

Q

(0,1,1)

(1,1,0)(1,0,1)

(0,0,0)

(0,0,1) (1,1,1)

(1,0,0)

(0,1,0)

I

Q

“1”

“0”

Currently:GMSK Modulation

EDGE:8PSK Modulation

“1 bit per symbol” “3 bits per symbol”

EDGEEDGE



21.4GMSKCS-4

15.6GMSKCS-3

13.4GMSKCS-2

9.05GMSKCS-1

Max data bitrate

over Um (kbps)

Modulation

methodCoding Scheme

GPRS GPRS CodingCoding schemesschemes



59.28-PSKMCS-9

54.48-PSKMCS-8

44.88-PSKMCS-7

29.68-PSKMCS-6

22.48-PSKMCS-5

17.6GMSKMCS-4

14.8GMSKMCS-3

11.2GMSKMCS-2

8.8GMSKMCS-1

Max data bitrate

over Um (kbps)

Modulation

methodCoding Scheme

EDGE Modulation and coding schemesEDGE Modulation and coding schemes



GPRS GPRS qualityquality vsvs CSCS

0

10

20

0 5 10 15 20 25 30

CS-1

CS-2

CS-3

CS-4

C/I [dB]

Th

rou

gh

pu

t pe

r tim

eslo

t



GPRS Link GPRS Link adaptationadaptation

•There are three reasons for GPRS Link Adaptation:

–Higher bit rates

–Low transfer delays

–Increased system capacity

•Four Coding Schemes available on DL (CS-1 to CS-4)

•GPRS Link Adaptation dynamically selects the most optimal codingscheme depending on the interference situation

•CS-1 and CS-2 is supported on UL and will be static



GPRS Link GPRS Link adaptationadaptation parametersparameters

From To Required BLER

CS-1 CS-2 < 4%

CS-2 CS-3 < 6%

CS-3 CS-4 < 2%

Change to a higher coding scheme

A change to a lower coding scheme is performed if the BLER > 10%

coding schemes for EIT Streaming TBFs

From To Required BLER

CS-1 CS-2 < 0.1%

CS-2 CS-1 > 1%

Up - and down switching points between



EGPRS Link EGPRS Link qualityquality controlcontrol

Link adaptation

- Estimate the quality- Choose coding scheme- Re-segmentation is possible

- Use very little coding at first - Send more coding if necessary- Receiver uses soft combining

Incremental redundancy

Possible to change mode during a TBF!

Link Quality Control



GPRS GPRS logicallogical channelschannels mappingmapping

BCCH

PDCH

Master PDCH

f 1

TS0 TS1 ... TS7

f 2

f n

Downlink: BCCH, Broadcast Control Channel

Downlink:PBCCH, Packet Broadcast Control ChannelPAGCH, Packet Access Grant ChannelPPCH, Packet Paging ChannelPNCH, Packet Notification ChannelPACCH, Packet Associated Control ChannelPDTCH, Packet Data Traffic ChannelPTCCH, Packet TA Control Channel DLUplink:PRACH, Packet Random Access ChannelPACCH, Packet Associated Control ChannelPDTCH, Packet Data Traffic ChannelPTCCH, Packet TA Control Channel UL

Downlink/Uplink:PDTCH, Packet Data Traffic ChannelPACCH, Packet Associated Control ChannelPTCCH, Packet TA Control Channel DL/ULNote: PCCCH printed in bold/italic



Master Master PacketPacket Data Data ChannelChannel

BCCH SDCCH TCH TCH TCH TCH MPDCH TCH

TCH TCH TCH TCH TCH PDCH PDCH PDCH

Primary PSET

Secondary PSET



GPRS GPRS –– flexibleflexible channelchannel allocationallocation (1)(1)

CSPSALLOC has the following values:

• No preference (default)

• CS first, PS last

• CS first, PS no preference

• CS last, PS first

• CS last, PS no preference

• CS last, PS last

• CS no preference, PS last

• CS no preference, PS first

PPPPB

C

CCCC

CCCC

Hoppin

g C

HG

R

PPPP

P P P PP



GPRS GPRS –– flexibleflexible channelchannel allocationallocation (2)(2)

PPPPTTB

PPPPPTTB

PPPPPTTB

PPPPTTB

MS1

MS1

MS2

MS1

MS2

MS1

MS2

The average number of DL TBFs per PDCH=1,0

and TBFDLLIMIT=1,8. No additional PDCHs are

requested.

The average number of DL TBFs per PDCH=2,0

and TBFDLLIMIT=1,8. Additional PDCHs are

requested.

The system orders allocation of one additional

PDCH since the TBF limit is reached.

There is now increased capacity in the cell and a

TBF re-reservation is performed for MS2.



MultiMulti ServiceService NetworkNetwork

Browsing

Messaging

WAP

PTT

GPRS/EGPRSNetwork

MMS



TotalTotal downloaddownload timetime –– Web Web browsingbrowsing

Client Server

”FTP Part”

”Signalling”



• Accessibility KPI:s

– GPRS Attach failures, PDP Context activation failures, GPRS Service

access failures…

• Retainability KPI:s

– FTP/WAP/Web/SMTP/POP3 transfer failures…

• Integrity KPI:s

– GPRS Attach time, PDP Context activation time, GPRS RTT, GPRS

Service access time and transfer rates,…

GPRS Performance GPRS Performance –– E2E E2E KeyKey Performance Performance IndicatorsIndicators



• IP Throughput

– Measures the total amount of data divide by the total time taken to

transmit it

• IP Latency

– IP latency measure the delay Gb - BSS - MS - BSS - Gb

• IP Transfer Interrupts

– Determines how often the IP transfer is interrupted

GPRS Performance GPRS Performance –– Radio KPIRadio KPI



Performance Performance levels analysislevels analysis

RLC thp

DL

RLC thp

UL

CCCH

congestion

PCU

congestion

Intra RA &

PCU CRS

Inter RA or

PCU CRS

CapacityInterference Mobility

Multislot

utilization

….

PDCH

sharing

No USF

or TFI

Limited

PDCHs

HW

fault

Sharing

PDCHs

Pre-

emption

No

PDCHR-PMO

Drive

test

MS

capability

IP Throughput IP Transfer Interrupts IP Latency



• IP Data Volume

• IP Throughput

• IP buffer discards

• IP Latency

• Radio Link Quality

• Traffic Load and sharing

• User Mobility

GPRS Performance GPRS Performance –– PerformancePerformance evaluationevaluation



• Three test environments are defined in order to evaluate the GPRS performance

– Ideal Environment

– Controlled Environment

– Operational Environment

GPRS Performance GPRS Performance –– PerformancePerformance evaluationevaluation


Technologie komunikacji bezprzewodowej 32Technologie komunikacji bezprzewodowej 32

„Technologie komunikacji bezprzewodowej”

„Wprowadzenie do przedmiotu”

Prezentacja jest współfinansowana przez Unię Europejską w ramach

Europejskiego Funduszu Społecznego w projekcie pt.

„Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej -zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do

zatrudniania osób niepełnosprawnych”Prezentacja dystrybuowana jest bezpłatnie

Politechnika ŁŁŁŁódzka, ul. ŻŻŻŻeromskiego 116, 90-924 ŁŁŁŁódźźźź, tel. (042) 631 28 83www.kapitalludzki.p.lodz.pl

Technologie komunikacji bezprzewodowej” „GPRS and radio ...

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