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NOKIA CS / NS / JRy Page 1

GPRS Network Planning Aspects

Telecom Network Planning Global

Jari Ryynnen


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Contents Nokia GPRS Releases

Nokia GPRS Network - Structure Network Planning Procedure and Services GPRS Mobility Management GPRS Power Control GPRS and GSM Resource Sharing GPRS Coding Schemes Capacity Planning Frequency Planning Coverage Planning GPRS Support in Totem Nokia NMS for GPRS GPRS Statistics and Counters GPRS and Other Features


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2000 2001 2002

GPRS Growth Stages & Nokia Releases

G P R S M o

b i l e P e n e

t r a

t i o n

0%

20%

40%

60%

Nokia Release 2Nokia Release 1

Low penetration Basic GPRS terminals

Cost effective networkwide introduction of GPRS

High GPRS penetration& growing traffic volumes GPRS is a standardfeature in all mobiles

Full set of GPRSservicesOptimised NWoperation

Growing penetration High end terminalsappear

Enhanced GPRSServicesIncreased GPRS NWcapacity

Nokia Release 3


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BTS BSC

MSC

SGSN

GGSN Intranet

PSTNNetwork

SS7NW

SMSC

HLR

CG

BillingSystem

Router Server

Local Area NW

Corporate

GPRSBackboneIP Network

BGInterPLMNNetwork

Gateway GPRSSupport Node

Firewall

Serving GPRSSupport Node

Border Gateway

ChargingGateway

Home LocationRegister

Short MessageService Centre

LegalIntercept

Nokia GPRS Network - Structure

Internet

DNSDomainNameSystems

PCU

Integrated NetworkManagement

NMS


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BTS BSC

SGSN

GGSN

GPRSBackboneIP Network

Gateway GPRS Support Node

Serving GPRSSupport Node

Nokia GPRS Network - Capacity

PCU

Packet Processing20 Mbit/s mean packet processing capacity (1.3 Mbit/s per PAPU)

48 Mbit/s peak packet processing capacitySubscribers120 000 Attached subscribersup to 2 IP contexts per subscriber

Data Transfer Capacity 16Mbit/s (4-8kpps) Supports 50 000 active PDP contexts

1 PCU 2Mbit/s data processing for GPRS One PCU can be freely connected up to 64 cells, 128 TRXs,

256 radio channelsMAX 8 PCUs / BSC



GPRS Network Planning Procedure

Capacity Planning

Frequency PlanningCoverage Planning Parameter Planning

Monitoring

Totem

NPS/X 3.3

Network Doctor NDW

PlanEdit

CDW

NMS/2000

GPRS PlanningServices

GPRS PlanningProcess

Pre-Planning Capacity Calculation for Dimensioning and Roll-

Out Planning

Coverage Design for Dimensioning and Roll-OutPlanning

Initial Network Configuration Detailled Planning

Traffic and Performance Analysis of ExistingNetwork

Definition of the Radio Interface Design Criteria

Preliminary Capacity Planning Preliminary Coverage / Frequency Planning



Radio NW Capacity Planning Capacity calculation in Netdim

Capacity calculation in Totem 3.1 Paging capacity estimation

(by adjusting the size of RAand LA )

Radio Network Planning

Speech traffic Data traffic C/I FH, IUO, IFH

Required # of TRXs Throughput / Capacity

INPUT OUTPUT

Radio NW Frequency Planning Frequency Planning with NPS/X 3.3 Throughput requirement must be considered in frequency

planningHigher Throughput -> Higher C/I requirement

Dedicated frequencies can be allocated for GPRS use if wanted Soft Capacity features (IFH, FH) increase the throughput



Coverage Planning Coverage prediction with NPS/X for the existing

network

Using the existing coverage or an additional coverageto improve the throughput:

Microcells

Separate indoor sites Metrosite Concept

Flexible capacity / coverage

GSM900 - GSM1800 TRXs in the sameBTS

Shared or Dedicated GPRS capacity (TS,TRX, band basis)

Radio Network Planning



Radio Network Planning Radio NW Parametrisation according to the stated quality targets

PlanEdit, NMS, CellularDataWarehouse (CDW) to handle all the parameters

GPRS activation parameters Cell reselection parameters (C1 and C2) PC parameters (Uplink in Release 1) Load control parameters

GPRS capacity (dedicated, shared)

HSCSD load control Quality Monitoring and Optimisation

New GPRS related counters in BSC Combined NMS/NetworkDataWarehouse (NDW) statistics for speech and GPRS GPRS support in TOM for drive tests

GPRS Interworking with other soft capacity features IUO/IFH (Regular layer for GPRS -> higher reuse, high throughput) FH (Reduction in interference -> higher throughput) Dual Band (Flexible, good quality -> high throughput)



System info 13

System info 14

System info 15

Frequency hoppinginformation -MA list etc... Packet power control &

interference measurementinformation

Informs if SI14 andSI15 are sent

GPRSMobile

Existing BCCH modified to include new parameters for GPRSNo reduction in cell traffic capacity when introducing GPRS Signaling capacity shared by Circuit Switched & GPRS

BCCH and GPRS



GPRS Mobility ManagementLocation

Area (LA)

Routing Area (RA)

SGSN

MSC/VLR

G s I n

t er f a

c e

Routing Areas used for GPRS Mobility Management For simplicity, can be the same than LA (GSM specs: RA



GPRS mobile cell selection / reselection the same than the CircuitSwitched idle mode cell selection

Cell is selected autonomously by the mobile MS uses C1 and C2 parameters for cell selection/reselection

(SYSTEM INFORMATION TYPE 3) GPRS handover is called as cell reselection Cell reselection can be done during the data connection

GPRS Cell Selection and Reselection

C1

C2



GPRS Cell Selection and Re-selection

Procedure for cell selection during data transmission: MS leaves the packet transfer mode and enters the packet idle mode in the

old cell

MS reads the system information messages in the new cell MS reports to the SGSN

Initiates uplink TBF (data, signalling or dummy), Makes cell update

Data transmission is started in the new cell No data retransmission in inter-PCU HO LLC frame is retransmitted if the PCU has been changed


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Uplink Power Control

- Due to bursty nature of traffic will not be as effective as for CircuitSwitched traffic- Open loop PC (specified in ETSI)- PC parameters for MS are transmitted on BCCH

Downlink Power Control- Not supported in the first release- Requires measurement reports

which will load the network

- Mobile near far effect a problem

MeasurementReports

UL Power Control DL Pow er

Control

Power controldata

GPRS Power Control


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Uplink Power ControlP CH = min( G0 - G CH - a*( C + 48),PMAX)

GCH , sets the minimum power level (default: 17 - GSM900, 18 - GSM1800) a , sets the slope for the uplink power level (default: 0.7/0.8)

C, normalised received signal level in DL directionG0, ETSI specified value, 39 - GSM900, 36 - GSM1800

PMAX, max power of the cell allowed for MS

MS Output Power as a function of Received DL Signal Level

05

1015

2025

3035

- 4 5

- 5 0

- 5 5

- 6 0

- 6 5

- 7 0

- 7 5

- 8 0

- 8 5

- 9 0

- 9 5

- 1 0 0

- 1 0 5

- 1 1 0

Received Signal Lev el (dBm)

M S T r a n s m

i s s

i o n

P o w e r

( d B m

)GSM900

GSM1800

MS power control withthe default values:


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Circuit Switched traffic has priority

Also GPRS dedicated time slots can be defined In each cell Circuit Switched & Packet Switched territories are defined Territories consist of consecutive timeslots GPRS can be set to favour the BCCH Transceiver -> higher throughput

CCCHTRX 1

TRX 2

TSCircuitSwitchedTerritory

Circuit /PacketSwitchedTerritoryDedicated

GPRSCapacity

TS TS TS TS TS TS

TS TS TS TS TS TS TSTS

Territory downgradeaccording to theCircuit Switched traffic

GPRS and GSM Resource Sharing

Territory upgrade until theDefault GPRS Capacity andin interval of TerritoryUpgrade Guard Time

Default GPRS capacityTemporaryGPRScapacity


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GPRS and GSM Resource SharingParameters

Parameters for Territory management:

GPRSenabled (BTS-level) GPRSenabledTRX (TRX-level) DedicatedGPRScapacity (BTS-level, %)

DefaultGPRScapacity (BTS-level, %) PreferBCCHfreqGPRS (BTS-level) TerritoryUpdateGuardTimeGPRS (BSC-level)

GPRS territory parameters can be changed when:

Online when the cell GPRS capability is set off by GPRSenabled parameter or The cell is locked.

effect of introducing GPRSon NW Quality & Capacity


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Several mobiles can share one timeslot

Mobiles are queued - maximum 7 Uplink, 9 Downlink Uplink State Flag used to tell which mobiles turn to transmit

TS 1

TS 2

TS 3

Multislot Mobile

Uplink State Flag

Timeslot selected to give maximum throughput Each mobile gets 1 / (no. of MS in queue) of the channels capacity

New MS

Resource Sharing between GPRS MS


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RLC / LLC Transmission

SGSN

LLC frame

-max 12160 information bits

-a header of 32 bits

-ack/non-acknowledged modes

LLC frameGb

BSC PCURLC blocks

RLC block

-160 information bits with CS-1= 8 kbit/s

-a MAC header of 21 bits

-acknowledgement every 18 blocks, if retransmissions more

often

BTS 4 interleaved bursts

LLC retransmissions

RLC retransmissions


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CodingScheme

Payload (bits)per RLC block*

Theoretical Data Rate(kbit/s)

CS1 181 9.05

CS2 268 13.4

CS3 312 15.6

CS4 428 21.4

More Data=

Less Error Correction

Nokia GPRSRelease 1

* RLC Block = 456 bits after puncturing

CS1 & CS2- Implemented in ALL Nokia BTS without HW change

CS3 & CS4- Will not fit in normal 16kbit/s Abis TRAU frame- Feature candidate for future release New TRX for TalkFamily & MetroSite

Not feasible for PrimeSite & 2nd Generation

D a

t a

E r r o r

C o r r e c

t i o n

GPRS Coding Schemes


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GPRS Coding SchemesThroughput versus C/I, link level simulations

02468

1012

1416

0 5 10 15 20 25

C/I

K b i t / s

CS-1

CS-2

CS-3

CS-4

0

10

20

30

40

50

0 5 10 15 20 25

C/I

K b i t / s

CS-1

CS-2

CS-3

CS-4

Minimum AverageTypical NW C/I

Minimum AverageTypical NW C/I

Network throughput - 1 Timeslot Network throughput - 3 Timeslots

Nokia Simulations - RLC polling interval = 18 blocks, non-frequency hopping)

All Nokia BTS support GPRS without any modification (CS1 & CS2) For signalling only CS1 is used (ETSI) 8 Timeslot parallel connections supported


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All Calls start with CS1

Change to CS2 based on successful transmission (without retransmissions)

Retransmissions always with the same coding scheme

After unsuccessful retransmissions, the coding changed back to CS1

Other alternatives also under study, like RXQUAL or C/I based linkadaptation

RequiredRetransmissions

All Blocks OK

LLCCS2

CS1LLC

CS2LLC

CS1LLC

All Blocks OK

All Blocks OK

CS2

CS1

GPRS Coding Scheme Selection


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Capacity Planning

GPRS bandwidth can be estimated via the voice time slotusage

E.g. 1 TRX cell with 7 traffic TSs Offered voice traffic: 2.88 Erl (Blocking=2%) For GPRS: 7 - 2.88 = 4.12 Erl

GPRS bandwidth

01234

56789

101112131415

1 2 3 4 5 6

number of TRXs

available GPRStime slots

no fixed GPRS time slotsfixed GPRS Tss = number of TRXsone fixed GPRS TS in the cell


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0

20

40

60

80

100

120

140

160

180

200

0 5 10 15 20 25 30 35 40

Circuit Switched Load (erl)

G

P R S C a p a c

i t y

( k b i t / s )

2% Blocking 2% Blocking 2% Blocking

2TRX (14TCH)

4TRX (30TCH)

6TRX (44TCH)

Based on Nokia Research Center simulations

BSS Capacity Dimensioning(CS1, control signalling included)


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GPRS User Throughput - Web Pages

0

2

4

6

8

10

12

14

1618

0 10 20 30 40 50 60 70 80

Offered GPRS Load kbit/s

M e a n k

b i t / s

1TS Mobile

3TS Mobile

6TS Mobile

2TRX Cell with 4.1 Erl Circuit Switched Load (50% loaded)

Note ! Due to larger packet sizes in FTP and email applications rates should be better

Coding Scheme CS1


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Retransmission Percentage GPRS Simulation Example

Retransmission percentage vs. average CIR

Macro 2/6, 1-slot, WWW traffic

0

20

40

60

80100

0 10 20 30

Average burs t CIR over the w hole network [dB]

%

Retransmission[%] CS-1

Retransmission[%] CS-2Retransmission[%] CS-3

Retransmission[%] CS-4


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C/I versus ThroughputNetwork level simulations

Throughputs vs. CIR. Shaded areas describe the regions where eachcoding scheme is best. C/I 20dB is required for high throughput -> requires a good quality network!


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Frequency PlanningSonera Simulations

Effect on frequency reuse patterns, voice traffic with 2% blocking asbackground load

Outage probability (C/I=9 dB, TRXs=3)

0

2

4

6

8

10

12

14

16

GPRS_0% GPRS_25% GPRS_50% GPRS_75% GPRS_100%

GPRS load

p ( % )

K=7K=9K=12K=13K=16K=19

Reuse 9 with voicetraffic + 100%GPRS load has the

same interferenceprobability thanReuse 7 with onlyvoice traffic!!

2-3 dB additionalinterference with fullGPRS load


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Coverage PlanningSonera Simulations

10 % outage probability is typical criteria in network planning

R r

Carrier C/I with outage probability 10 %

0

5

10

15

20

25

30

0 . 2

5

0 . 3

0

0 . 3

5

0 . 4

0

0 . 4

5

0 . 5

0

0 . 5

5

0 . 6

0

0 . 6

5

0 . 7

0

0 . 7

5

0 . 8

0

0 . 8

5

0 . 9

0

0 . 9

5

1 . 0

0

r/R

C / I ( d B )

GPRS_0%

GPRS_50%

GPRS_100%

50% GPRS loadworsens C/I by 1 dB

100% GPRS loadworsens C/I by 2 dB


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GPRS Support in Totem

Capacity Calculation for Dimensioning and Roll-Out Planning

Coverage Design An estimated GPRS throughput (kbit/s) with different channel

coding schemes in an existing network can be shown

A coverage plan to fulfil the required GPRS throughput can beprepared

Coming 12/99??

Speech traffic Data traffic C/I FH, IUO, IFH

Required # of TRXs Throughput / Capacity

INPUT OUTPUT


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Nokia NMS for GPRS

GSMIP

Q

3

SN

MP

Nokia NMS for GPRS

Combined GSM and Data Network

management Integrated access: allapplications/tools can have aseamless access from the sameterminal

Integrated fault management:- SNMP traps from the IP backbone- Q3 Alarms from the GSM network

Integrated PerformanceManagement allowing thecollection and monitoring of bothGSM and data related counters

Seamless growth path from the current NMS/2000 GSM managementsystem to the GPRS System Solution

Process centric view


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Process centric viewOperator Processes in GPRS Network Management

Adding SGSN's Adding GGNS'sDownloading GPRS SW

Radio Network PlanningIP network PlanningIP Address managementSecurity Planning

Network MonitoringTrouble ManagementActivating GPRSAdding/changing GPRSsubscriber parameters

PerformanceReporting

Building

Planning

Operating


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GPRS Statistics and Counters A lot of new counters are proposed for GPRS. Here are some examples:

Number of RTSLs requested / allocated for one TBF

1 2 3 4 5 - 8

RequestUplink 4 17 21 13 0

RequestDownlink 2 13 22 15 1

AllocatedUplink 3 15 17 8 0

AllocatedDownlink 3 10 17 8 1

Number of data RLCblocks

Number of data retransmittedRLC blocks

Number of RLC controlblocks

CodingScheme Uplink Downlink Uplink Downlink Uplink Downlink

CS 1 56 108 8 22 8 20

CS 2 27 80 3 10 - -

BSC St ti ti f GPRS


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BSC Statistics for GPRS

Available Measurement

PCU measurement - 65 counters

Traffic measurement - 7 counters

Resource availability measurement - 4 counters

Resource access measurement - 30 counters

Handover measurement - 2 counters

Availability measurement - 1 counter



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Formula examples :

Comparing of CS1 & CS2

Ratio of CS1 and CS2 for RLC data blocks = (A + B) / (C + D)

Comparing of uplink and downlink

Ratio of uplink and downlink RLC data blocks = (A + C) / (B + D)

where A = Counter for number of RLC data blocks in uplink with CS1 coding scheme

B = Counter for number of RLC data blocks in downlink with CS1 coding schemeC = Counter for number of RLC data blocks in uplink with CS2 coding scheme

D = Counter for number of RLC data blocks in downlink with CS2 coding scheme


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Formula examples :

Ratio of control blocks and data blocks on uplink and downlink

Ratio of RLC control blocks and data blocks CS1 coding = (E + F) / (A + B)

where A = Counter for number of RLC data blocks in uplink with CS1 coding schemeB = Counter for number of RLC data blocks in downlink with CS1 coding scheme

E = Counter for number of control RLC blocks in uplink with CS1 coding scheme

F = Counter for number of control RLC blocks in downlink with CS1 coding scheme


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GPRS and Other FeaturesIUO/IFH:

GPRS MS doesn't have access to the IUO/IFH super layer At start low GPRS traffic -> OK to use only regular layer

Release1 does not support Network requested cell re-selection

No IUO C/I estimation

Less capacity for GPRS

High reuse on the regular layer -> high throuhputMore interference for the regular layer because of GPRS traffic

Frequency Hopping: Basically FH improves the GPRS throughput

With tight reuse schemes the GPRS throughput will suffer

With BB FH, TS0 cannot be used for GPRS (GSM specs., different FH group)BCCH TRX preference doesnt help with BB FH


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GPRS and Other Features

Dual Band:

DB 1800 layer is normally less interfered -> more suitable at the beginning for the GPRS service

In Idle mode, the C2 parameter is used to suck the DB traffic to 1800 layer,the same parameter is used in GPRS Release 1 for GPRS cell selection

HSCSD: Has priority over GPRS but can be controlled by HSCSD load parameters

Extended cell: GPRS is not supported in Extended cell in Release1 -- so ETRX can not carryGPRS TCHs

Satellite Abis:

GPRS is not supported over Satellite Abis (long delay)

Forced Handover For O&M Reason: If there are GPRS TSLs in the TRX to be blocked, BSC moves those TSLs toCS territory before TRX blocking


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ExplanationsTBF

A Temporary Block Flow (TBF) is a physical connection used by the two RRentities to support the unidirectional transfer of LLC PDUs on packet dataphysical channels.

The TBF is allocated radio resource on one or more PDCHs and comprises anumber of RLC/MAC blocks carrying one or more LLC PDUs.

A TBF is temporary and is maintained only for the duration of the data transfer (i.e. until there are no more RLC/MAC blocks to be transmitted and, in RLCacknowledged mode, all of the transmitted RLC/MAC blocks have beensuccessfully acknowledged by the receiving entity).

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