Part 2 planning of 3G

Part 2:UMTS Planning

TRAFFIC MODELLING

AIR INTERFACE DIMENSIONING

NOMINAL CELL PLAN

RADIO NETWORK DESIGN

• Site type• Site Count• Site to Site Distance• Carrier RequiredHardware dimensioning• Channel Elements

• Input Analysis• Mapping of Radio Access Bearer

Use TEMS Cellplanner and

digitized map

Radio Planning Process

Overall Planning Process The overall Planning Process can be described with the following figure:

• 3G neighbour lists• 2G neighbour lists• Antenna tilts• Local area

parameter tuning

• Site selection• Site design• 3G neighbour lists• 2G neighbour lists• Scrambling codes• Location areas• Routing areas• RNC areas

Link budget analsysis

• RF carriers• Sectorisation• ROC to CEC• Node B power• Baseband proc.• Transmission

CapacityEvolution

Performance Monitoring

SystemDimensioning

Radio Network Planning

Pre-launch Optimisation

Post-launch Optimisation


parameter tuning

• Site selection• Site design• 3G neighbour lists• 2G neighbour lists• Scrambling codes• Location areas• Routing areas• URA areas

Link budget analysis

• Node B count & configuration

• Adapter count & configuration

• Transmission capacity &

configuration

• RF carriers• Sectorisation• System modules• Node B power• Baseband proc.• Transmission

Performance Monitoring

Wide area parameter tuning


parameter tuning• Additional sites• User experience

optimisationoptimisation• HSDPA• Microcells••

Dimensioning Objective

To dimension radio capacity with reasonable accuracy before using planning tools

To establish the parameters and assumptions to be used throughout the project

Input Data

Environment and Coverage– Area to cover and coverage degree– Channel Model for EbNos– Propagation Model (Ok-Hata > 1km, Walfish < 1km)

Service Characteristics– Services and RABs– Grade of Service– UE Type

Input Data

Subscriber Density and Subscriber Behaviour– Number of Subs per area– Traffic per Sub at Busy Hour– Activity Factor for services– Body Loss

System Design Data– Retransmissions– Handover parameters– Site Configuration– Bandwidth (# carriers)– Load

Traffic Profile

Average user in BH– Voice/Video in mE– PS in kB/BH

UL/DL Asymmetry = 15-20% BH Traffic = 10-15% Daily Traffic

Traffic model in average Short term Medium term Long termper user during BH after 1 year after 2-3 years after 4 to 6 years

Voice (mE) 8 to 30 10 to 30 10 to 30Typical voice (mE) 15 to 20 15 to 20 15 to 20

Typical CS64 data (mE) 0,1 to 0,5 around 1 2 to 3PS data (KByte/BH) 20 to 100 60 to 250 up to 500 to 600

Typical PS data(KB/BH) 40 to 60 100 to 150 200 to 300

Air Interface DimensioningAssume an

uplink loading

Calculate uplinkcoverage/Lmax

Calculate uplink capacity

Estimate sitecountfor coverage

Estimate sitecountfor capacity

Balanced?

Yes

No

Calculate PCPICH, ref

based on UL Lmax

CalculateDL Capacity

Calculate PDCH

Calculate PCCH, ref

DL Capacityfulfill req.

No

Finished

Yes

Input Data

Link Budget Method - Overview

- PHSDPA

- HSDPA cell average throughput

- HSDPA cell border throughputDone!

Lsa or PDCH

too large

Lsa or PCCH

too large

Average DL network load (Q)

- Link budget margins

- HW configuration

- Cell border parameters

Uplink PS & CS traffic

StartUL link budget

Step 1Lsa

CPICH link budget

Step 2

PCCH,

Lsa

DL link budget

Step 3

PCCH, PDCH, Lsa,

HSDPA dimensioning

Step 4

What decides HSDPA cell border throughput and cell average throughput is basically Lsa and power left for HSDPA.The dimensioning is done in 4 steps:Step 1Lsa is given from link budget calculations, starting with R99 UL link budget that decides Lsa.Step 2Lsa is used in the CPICH link budget to calculate needed CPICH and CCH power.If the needed power turns out to be too large, Lsa needs to be reduced (redoing the UL link budget, i.e step 1)Step 3Lsa is used to calculate needed power for R99 RABs, both per link (as a normal link budget when the user is standing on the cell border) and as average needed RBS power (when loading the system with many users that are distributed within the cell).If the needed power turns out to be too large, Lsa needs to be reduced (redoing the UL link budget, i.e step 1)Step 4Lsa and needed power for CCH and R99 RABs are used to calculate HSDPA throughput.

InputsThe ”reddish” color shows different inputs that affects the end result.-The amount UL CS and PS traffic decides the UL link budget (noise rise).-Link budget margins (antenna gain, building penetration loss, body loss, etc), HW configurations (RBS power) and DL network load decides Lsa. Note that the network load is assumed to 100% for HSDPA dimensioning.

System Reference Point

Eb/No vs BLER

Eb/No = 1 dBA

Eb/No = 6 dBB

A BER > B BER

Propagation models predict only mean values of signal strength Mean signal strength value fluctuates, the deviation of the local has a

nearly normal distribution in dB, compared to the predicted mean Probability that the real signal strength will exceed the predicted one

on the cell border is around 50% For higher coverage probability than 50% an additional margin has to be

added to the predicted required signal strength The LNF margin depends on:

Radio channel properties (channel model) Area type (Clutter type) Required coverage confidence soft handover gain

Log Normal Fade Margin

75 85 90 95 98

Rural, Suburban –4.1 –1.7 0 2.3 4.6

Urban –3.9 –0.9 1.1 4.1 7.2

Urban Indoor –3.8 0.6 3.4 7.5 12.1

Dense Urban Indoor –3.8 1.1 4.3 9 14.3

EnvironmentArea coverage %

Uplink Dimensioning

Cell range and cell area can be calculated

The number of sites required for meeting coverage requirement can be found

Max path loss due to propagation

Uplink Service Service Speech CS Data PS Data Service Rate 12.2 64 64 kbpsTransmitter - Handset Max Tx Power 21 21 21 dBmTx Antenna Gain 0 2 2 dBiBody Loss 3 0 0 dBEIRP 18 23 23 dBmReceiver - Node B Node B Noise Figure 3 dBThermal Noise -108 dBmUplink Load 50 %Interference Margin 3.0 dBInterference Floor -102.0 Service Eb/No 4.4 2 2 dBService PG 25.0 17.8 17.8 dBReceiver Sensitivity -122.6 -117.8 -117.8 dBRx Antenna Gain 18.5 18.5 18.5 dBiCable Loss 2 2 2 dBBenefit of using MHA 2 2 2 dBUL Fast Fade Margin 1.8 1.8 1.8 dBUL Soft Handover Gain 2 2 2 dBBuilding Penetration Loss 12 12 12 dBIndoor Location Prob. 90 90 90 %Indoor Standard Dev. 10 10 10 dBSlow Fade Margin 7.8 7.8 7.8 dBIsotropic Power Required -121.5 -116.7 -116.7 dBAllowed Prop. Loss 139.5 139.7 139.7 dB

HSDPA’s Effect on Uplink Coverage Service PS Data PS Data PS Data PS Data Service Rate 16 64 128 384 kbpsTransmitter - Handset Max Tx Power 24 24 24 24 dBmHS-DPCCH Overhead 4.6 2.8 1.6 1.1 dBTx Antenna Gain 2 2 2 2 dBiBody Loss 0 0 0 0 dBEIRP 21.4 23.2 24.4 24.9 dBmReceiver - Node B Node B Noise Figure 3.0 dBThermal Noise -108.0 dBmUplink Load 50.0 %Interference Margin 3.0 dBInterference Floor -102.0 dBmService Eb/No 2.5 2 1.4 1.7 dBService PG 23.8 17.8 14.8 10.0 dBReceiver Sensitivity -123.3 -117.8 -115.4 -110.3 dBRx Antenna Gain 18.5 18.5 18.5 18.5 dBiCable Loss 2 2 2 2 dBBenefit of using MHA 2 2 2 2 dBUL Fast Fade Margin 1.8 1.8 1.8 1.8 dBUL Soft Handover Gain 2 2 2 2 dBBuilding Penetration Loss 12 12 12 12 dBIndoor Location Prob. 90 90 90 90 %Indoor Standard Dev. 10 10 10 10 dBSlow Fade Margin 7.8 7.8 7.8 7.8 dBIsotropic Power Required -122.2 -116.7 -114.3 -109.2 dBAllowed Prop. Loss 143.6 139.9 138.6 134.1 dB

BIUL - Noise Rise is referred as the increase in receiver noise floor when a system is more loaded.

0

2

4

6

8

10

12

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9Load

Inte

rfe

ren

ce i

ncr

ease

DI [

dB

]

E.g. 20%=0,97dB, 50%=3dB

where Q is the uplink system loading

UL Noise Rise

Maximum Pathloss (Okumura-Hata)

Lpath = A - 13.82log(ha) + (44.9 - 6.55log(ha))logR - a(hm) [dB]

Where the following A values are valid for 2050 MHz:A = 155.1 in urban areas ha base station antenna height [m= 147.9 in suburban and semi–open areas hm UE antenna height [m]= 135.8 in rural areas R distance from transmitter [km]= 125.4 in open areas a(1.5) = 0

Range

R = 10,

where: = [Lpath - A + 13.82logHb]/[44.9 - 6.55logHb]

Use Walfish Ikegami if cell range <1km

Calculating Cell Range

232

3RArea= 23

8

9RArea=

RSite to Site 3=

232

3RArea=

R RR

R3=Site to SiteR23=Site to Site

Calculating Site Distances

Transmitter (RBS) is in a single point, Receivers (Terminals) are distributed in the cell

DL coverage and capacity are not only dependent on the number of terminals, but also on their distribution in a cell and their relative position towards other cells

Downlink Dimensioning

Downlink Service Service Speech CS Data PS Data PS Data PS Data Service Rate 12.2 64 64 128 384 kbpsTransmitter - Node B Max Tx Power (Total) 43 dBmMax Tx Power (per Radiolink) 34.2 37.2 37.2 40.0 40.0 dBmCable Loss 2 2 2 2 2 dBMHA Insertion Loss 0.5 0.5 0.5 0.5 0.5 dBTx Antenna Gain 18.5 18.5 18.5 18.5 18.5 dBiEIRP 50.2 53.2 53.2 56.0 56.0 dBmReceiver - Handset Handset Noise Figure 8 dBThermal Noise -108 dBmDownlink Load 80 %Interference Margin 7.0 dBInterference Floor -93.0 Service Eb/No 7.9 5 5 4.7 4.8 dBService PG 25.0 17.8 17.8 14.8 10.0 dBReceiver Sensitivity -110.1 -105.8 -105.8 -103.1 -98.2 dBmRx Antenna Gain 0 2 2 2 2 dBiBody Loss 3 0 0 0 0 dBDL Fast Fade Margin 0 0 0 0 0 dBDL Soft Handover Gain 2 2 2 2 2 dBMDC Gain 1.2 1.2 1.2 1.2 1.2 dBBuilding Penetration Loss 12 12 12 12 12 dBIndoor Location Prob. 90 90 90 90 90 %Indoor Standard Dev. 10 10 10 10 10 dBSlow Fade Margin 7.8 7.8 7.8 7.8 7.8 dBIsotropic Power Required -90.5 -91.2 -91.2 -88.5 -83.6 dBAllowed Prop. Loss 140.6 144.4 144.4 144.5 139.6 dB

Uplink v/s Downlink

HSDPA Dimensioning

Average cell throughput– What is the expected average HSDPA capacity?

Cell border throughput– What is the expected HSDPA cell border throughput?

Decided by:– Signal Attenuation, Lsa

– Power left for HSDPA

HS-DSCH power calculation

Treated as true best effort in dimensioning– Will take whatever power that is left in RBS after common

channels and dedicated channels has taken their part– No ”headroom” is needed

time

Power

Max cell power

CCH power

HS-SCCH power

Admission control thresholdHS-DSCH power

DCH power

HS-DSCH power calculation (2)

PHS-DSCH calculated as:

DCHASCCHHSDCHCCHreftotDSCHHS PPPPPP ,

Power needed byDCH RABs (PS & CS)

RBS power atTx reference point

Common ChannelPower (CPICH, BCH, etc.)

High-Speed Shared Control Channel power

Power needed forA-DCH on DL

Traffic estimation

• The traffic estimation requires information related to the network topology, subscribers & traffic:

• Cell Area from Coverage Dimensioning• Subscriber density from Marketing• Subscriber traffic profile from Marketing

Basic Traffic Model

Air Interface Dimensioning

Channel Card Dimensioning

RNC Dimensioning

Iub Dimensioning

Iu Dimensioning

Iur Dimensioning

+

Topology Subscribers

Subs densityCell area Traffic / subscriber

Traffic / cell

Traffic / site

Load Calculation: Uplink Load

jjb

jj

NE

RWL

1

/

/1

1

0

N

jjUL L

0

νj: Activity factor; for Speech some 67% due to VAD/DTX; for Data: 1

Load Lj

of subscriberwith Service j

ηUL

totalCell Load

Activity Factor

Processing Gain

0

2

4

6

8

10

12

14

16

18

10

20

30

40

50

60

70

80

90

95

98

loading/%

los

s/d

BIn

terf

eren

ce M

argi

n [d

B]

UL = 30 – 50 %

Cell Load [%]

Load Calculation Formulas in analogy toH. Holma “WCDMA for UMTS”

Inter-Cell Interference: Little i– In the real environment we will never have separated cell. Therefore, in the load factor calculation the other cell

interferences should be taken into account.– This can be introduced by means of the Little i value, which describes how much two cells overlap (bigger

overlapping more inter-cell interferences)

Iown

Iother

ceinterferen cellown

ceinterferen cellother i

Inter-Cell Interference Ratio“Little i”

j

jjb

jjjUL

NE

RWiLi

1

/

/1

1)1()1(

0

Uplink Load calculation• Simplified UL load equation UL DCH capacity

– for 1 service type j only– W/Rj >> (Eb/No)j

• Nj: No. of Trunks

• Nj x Rj = Cell Throughput = Capacity [kbps]

j

jbjjUL RW

NoENi

/

)/()1(

Downlink Load calculation

Cell Type α

Macro Cell 0.4 – 0.9

Micro Cell > 0.9

Load Calculation Examples– Load factor for different services has to be calculated separately, total load is then the sum of

different services in the cell area– UL/DL single connection load examples are shown in the table below– For example 50 % UL load means on average 50 speech users or about 9 64 kbits/s users/cell in

a 3-sector (1+1+1) configuration

Services UL Fractional Load DL Fractional Load12.2 kbit/s 0,97% 1,00%64 kbits/s 4,80% 6,21%128 kbits/s 8,56% 11,07%384 kbits/s 22,89% 29,59%Total Load 37,22% 47,87%

Planning Tasks

– Scrambling Code Planning– Neighbour List Planning– Location, Routing and UTRAN Registration Area

Planning

34

• ALLOCATION CRITERIA– Additional conditions on Ec/Io– Reuse distance– SC domain assigned to the cell– Number of scrambling codes per cluster

• ALLOCATION STRATEGIES– Clustered

• Use a minimum number of clusters– Distributed per Cell

• Use as many clusters as possible– One Cluster per site

AUTOMATIC ALLOCATION7.

S

CR

AM

BL

ING

CO

DE

PL

AN

NIN

G

Cluster =Scrambling Code Group

35

• EXAMPLES OF ALLOCATION STRATEGIESAUTOMATIC ALLOCATION

CLUSTEREDDISTRIBUTED PER CELL

ONE CLUSTER PER SITE

Planning Tasks


Planning

Introduction• There are the following types of neighbor lists

• Intra-frequency (3G to 3G)• Inter-frequency (3G to 3G)• Inter-system

• 3G to 2G• 3G to LTE

• Neighbor lists are usually refined during pre-launch or post-launch optimization

• Neighbor list planning should be as accurate as possible• Impact upon pre-launch optimization has to be recognized• Pre-launch optimization often limited to specific drive route which may not

identify all neighbors• Neighbor list tuning usually achieves the greatest gains during pre-launch

optimization

• High quality neighbor lists are essential for a good performance of the network

Intra-frequency

Inter-frequency

Inter-system 3G to 2G

Inter-system 3G to LTE

CPICH Ec/Io SC100SC200

Drop

Cell Selection

Time

Missing neighbours can be identified from UE log files:

1) Decrease of CPICH Ec/Io until connection drops

2) Then sudden improvement after cell selection

Example: SC200 missing from neighbour list associated with SC100

UE movement

Intra-Frequency Neighbors (3G to 3G) (1/2)• Used for cell re-selection, SHO, softer handover & intra-frequency HHO• Missing neighbors

• Poor signal to noise ratio (EC/I0)• UEs transmitting with high power close to neighboring site, but not served by it

• Excessive number of neighbors• Increase of UE measurement time• May lead to deletion of important neighbors during soft handover

• Intra-frequency neighbor lists are transmitted in SIB11 & dedicated measurement control messages

• When a UE is in SHO the neighbor lists belonging to each of the active set AS cells are combined

• Neighbor lists are combined for both intra-RNC & inter-RNC SHO

• The RNC generates a new intra-frequency neighbor list after every AS update procedure (events 1a, 1b & 1c)• The RNC transmits the new intra-frequency neighbor list to the UE if the new list differs from the existing one• 3GPP allows the network to specify max. of 32 intra-frequency cells for the UE to measure (1-3 AS cells + 29-

31 neighbors)

Active set update

Intra-Frequency Neighbors (3G 3G) (2/2)

AS: Active Set

Inter-Frequency IF Neighbors (3G to 3G) (1/2)• Used for IF cell re-selection & inter-frequency HHO• Following procedures are not supported:

• IF handover from Cell_FACH• IF handover while anchoring at an RNC

• Missing neighbors:• UE cannot escape bad actual carrier• Poor signal to noise ratio (EC/I0) and / or coverage (RSCP)

• Excessive number of neighbors• Increase of UE measurement time• May lead to selection of non optimum target cell

• IF neighbor lists are transmitted in SIB11 and dedicated measurement control messages

• IF neighbors are usually introduced after network launch; refining them is a post launch optimization task

IF: Inter-Frequency

Inter-frequency neighbour list

Inter-Frequency Neighbors (3G to 3G) (2/2)• When a UE is in intra-RNC SHO the neighbor lists belonging to each of the active set cells are combined

• Neighbor lists are not combined for Inter-RNC SHO (no support of inter-frequency neighbor signaling across Iur)

• The RNC generates a new inter-frequency neighbor list after an active set update procedure, if compressed mode CM is not running

• In CM the neighbor list valid at the time to trigger the hard handover is taken• NSN allows the network to specify a max. of 32 inter-frequency cells for the UE to measure per carrier, and

a max. of 48 cells for all carriers

Priorities for generating combined neighbor lists• Neighbor cells which are common to 3 AS cells• Neighbor cells which are common to 2 AS cells• Neighbor cells which are defined for only 1 AS set cell

AS: Active Set

Inter-System Neighbors (3G to 2G) (1/2)• Used for cell re-selection and (hard) handover towards 2G• GSM neighbor list can be based upon existing BSC 2G neighbor list if 3G and 2G sites are co-sited• If an operator has both GSM900 and DCS1800 networks then inter-system neighbors can be defined

only for GSM900 or only for DCS1800• The following procedures are not supported

• Inter-system handover from Cell_FACH• Inter-system handover while anchoring at an RNC

• Missing neighbors• UE cannot escape bad actual carrier• Poor signal to noise ratio (EC/I0) and / or coverage (RSCP)

• Excessive number of neighbors• Increase of UE measurement time• May lead to selection of non optimum target cell

• Inter-system neighbor lists are transmitted in SIB11 and dedicated measurement control messages

• The RNC instructs the UE to measure all GSM neighbors (RSSI), but to verify the BSIC for one specific neighbor only

Just like Inter-frequency

Inter-System Neighbors (3G to 2G) (2/2)• When a UE is in intra-RNC SHO the neighbor lists belonging to each of the active set cells are combined

• Neighbor lists are not combined for inter-RNC SHO (no support of inter-system neighbor signaling across Iur)

• The RNC generates a new inter-system neighbor list after an active set update procedure, if compressed mode is not running

• In compressed mode the neighbor list valid at the time to trigger the HHO is taken• 3GPP allows the network to specify a maximum of 32 inter-system cells for the UE to measure

Priorities for generating combined neighbor lists• Neighbor cells which are common to three

active set cells• Neighbor cells which are common to two

active set cells• Neighbor cells which are defined for only

one active set cell

Inter-system neighbour list

Maximum Neighbor List Length (1/2)• SIB11 is used to instruct the UE which cells to measure in RRC Idle, CELL_FACH &

CELL_PCH• According TS 25.331 contradiction about SIB11

• Should be able to accommodate information regarding 96 cells

Intra-frequency

Inter-frequency

Inter-system 3G to 2G

Inter-system 3G to LTE

Maximum Neighbor List Length (2/2)• Enables transmission of all defined neighbors

• 32 intra-frequency• 32 inter-frequency• 32 inter-system (both to 2G and LTE together)

Urban

Suburban

3G intra-freq

Rural

3G inter-freq inter-sys 3G to 2G

14

1010

14

1010

16

1212

Typical Neighbor List Lengths• Neighbor list lengths are scenario dependant, e.g.

• Simple layering (two or more carriers serving the same coverage area)• Hierarchical cell structure (macro umbrella cells and underlying micro cells)

• Typical values

Planning Tasks


Planning

Node B

MSC

UE

RNC

Iu cs

SGSN

Single RRC Connection

Iu ps

CS state

PS state

CS state

PS state

Two Iu Signalling Connections

Core Network Service States• To describe the presence of a UE within the core network, each service domain (CS or

PS) uses independently the following state machine• Detached (UE not registered)• Idle (UE registered, but no Iu signaling connection exists• Connected (UE registered and Iu signaling connection exists)

• In idle and connected mode the core network has to track the location of a UE• Location area LA used by CS domain• Routing area RA used by PS domain• Both LA and RA are handled by the non access stratum NAS layer within the core network and the UE

• The position of the UE has to be updated• Idle mode if UE moves to another LA or RA• Connected mode if UE moves to another cell

or UTRAN registration area

• Identification of LA• Globally using a Location Area Identification (LAI)• LAI: concatenation of Mobile Country Code (MCC), Mobile Network Code

(MNC) & Location Area Code (LAC)

• The cells of a LA can belong to• One or several RNC• Just to a single MSC/VLR

• The size of a LA can range between• Single cell (minimum)• All cells connected to a single VLR (maximum)

• The mapping between LA and its associated RNCs is handled by the MSC/VLR• The mapping between LA and its cells is handled by the RNC

Location Area

2 Bytes for LAC

00 00 and FF FE values reserved

Almost 65536 LAC values per PLMN

VLR area

LA3

LA2

LA1

• Identification of LA• Globally using a Routing Area Identification (RAI)• A LAI is a concatenation of Location Area Identification (LAI) & Routing Area Code

(RAC)

• The cells of a RA can belong to• One or several RNC• Just to a single SGSN• Just to a single LA

• The size of a RA can range between• Single cell (minimum)• All cells belonging to a single LA (maximum)

• The mapping between RA and its associated RNCs is handled by the SGSN• The mapping between RA and its cells is handled by the RNC

1 Byte for RAC

256 RAC values per of LA

Routing Area

LA split into several RAs

RA2

RA1

LA1

LA3RA3

LA identical with RA

Paging Capacity• NSN RAN provides either a 8 kbps or 24 kbps PCH transport channel on the S-CCPCH• One page message has a size of 80 bits and is transmitted within 10 ms (1 radio frame)• With 8 kbps PCH thus 100, with 24 PCH 300 UEs can be paged per second• In practice in most cases the 8 kbps PCH clearly is sufficient

Trade Off Between Paging and LA/RA Update• Number of cells per LA/RA: to be designed as compromise between signaling traffic

paging and LA/RA update

Small LA/RA• Less page traffic, as

page messages transmitted to fewer cells

• More LA/RA updates, as more cells at LA/RA borders

• Optimum design if network dominated by slow moving UEs

Large LA/RA• More page traffic, as

page messages transmitted to more cells

• Less LA/RA updates, as less cells at LA/RA borders

• Optimum design if network dominated by fast moving UEs

Splitting of LA into several RA• Usually LA and RA

are planned to be identical

• Splitting of LA into smaller RAs needed only in case of high PS page traffic

Design of LA/RA Borders• 2G LA/RA borders often good starting point of 3G LAs/RAs, as usually already

optimized• To avoid large number of LA/RA updates, borders should not

• Go parallel to major roads / railway lines• Traverse areas of high subscriber density

• To verify success of LA/RA update procedure, LA/RA borders should cross clusters defined for drive test

LA1 LA2

Road

• A LA/RA can have both 2G and 3G cells• Requires unique 2G and 3G Cell Identities (CI) and Cell Global Identities (CGI)• A CGI is a concatenation of Location Area Identification (LAI) and Cell Identity (CI)

• CN not able to distinguish between 2G & 3G network for paging purpose both 2G & 3G paging appears on both the 2G & 3G network

• Less probable that UE misses paging message when it completes inter-system cell re-selection

• But increased paging traffic on both systems and coordinated cell identities needed

• In practice implementation of the same location areas for 2G & 3G may be difficult• 2G & 3G network often have different coverage area• Not all sites are co-sited

LA/RA with both 2G and 3G Cells

UE States Idle mode

– No connection to radio network (No RRC connection established)– This minimizes resource utilization in UE and the network

CELL_FACH mode– User Equipment (UE) in Connected Mode (has an RRC Connection to radio

network) – UE uses the common transport channels RACH or FACH– If the parameter interFreqFDDMeas Indicator = 1, the UE will evaluate cell

reselection criteria on inter-frequency cells (0)

CELL_DCH mode– User Equipment (UE) in Connected Mode (has an RRC Connection to radio

network)– UE uses dedicated channels for transmitting data and signalling

System Information

System parameters are broadcast on BCCH. It has information regarding Idle Mode Behaviour.

The System Information elements are broadcast in System Information Blocks (SIB’s). Each SIB contains a specific collection of information.

Idle mode Functions

PLMN Selection Cell Selection and

Reselection Location Area (LA) and

Routing Area (RA) updating

Paging System Information

Broadcast

PLMN Selection PLMN selection performed upon power on or upon recovery from lack of coverage

If there is no last registered PLMN, or if it is unavailable, the UE will try to select another PLMN “AUTOMATICALLY” or “MANUALLY” depending on its operating mode

Manual mode– UE displays all PLMNs (allowed and not allowed) by scanning all frequency

carriers– The user makes a manual selection and the UE attempts registration on the

PLMN

Automatic mode– Each PLMN in the user-controlled PLMN list in the USIM, in order of priority– Each PLMN in the operator-controlled PLMN list in the USIM– Other PLMNs according to the high-quality criterion

Roaming– Roaming is a service through which a UE is able to obtain services from another

PLMN– The UE in Automatic mode, having selected and registered a Visited PLMN

(VPLMN) periodically attempts to return to its Home PLMN (HPLMN) according to a timer. Default = 30mins

StartStart

Stored InformationCell selection

Stored InformationCell selection

Initial Cell Selection

Initial Cell Selection

Cell selectionwhen leaving

connected mode

Cell selectionwhen leaving

connected modeConnected

mode

Connected mode

In Automaticmode, new

PLMNselection

In Automaticmode, new

PLMNselection

Camped on an Acceptable cell

(Limited Service)

Camped on an Acceptable cell

(Limited Service)

Camped Normally

Camped Normally

Cell Reselection

Process

Cell Reselection

Process

No suitable cell found

Suitable cell found

Location registration failed

Measurementsevaluation

Suitablecell selected



Suitable cell found

Cell selection and reselection procedure

Cell Selection

UE looks for a suitable cell in the selected PLMN and camps on to it

Cell search procedure– UE acquires slot synchronization using P-SCH– It acquires frame synchronization using S-SCH– Primary scrambling code is obtained from CPICH

UE then monitors the paging and system information, performs periodical radio measurements and evaluates cell reselection criteria

Strategies used for the cell selection process:– Initial Cell Selection: UE has no knowledge of the WCDMA radio channels

UE scans all WCDMA radio frequency channels to find a suitable cell with the highest signal level and read BCCH

The PLMN is determined from the mcc and mnc in the MIB in BCCH

– Stored Information Cell Selection: UE knows the carrier frequencies that have previously been used

Cell Selection Parameters

For cell selection criteria the UE calculatesSqual = Qqualmeas - qQualMin (for WCDMA cells)Srxlev = Qrxlevmeas - qRxLevMin – Pcompensation (for all cells)

Where Pcompensation = max(maxTxPowerUL – P,0)P is output power of UE according to class

Cell selection criteria (S criteria) is fulfilled whenSqual>0 ( for WCDMA cells only)and Srxlev>0

Recommended valuesqQualMin= -19dBqRxLevMin= -115dBmmaxTxPowerUL = 24

Cell Reselection

Allows UE’s to move between cells in idle and cell_FACH connected mode

Always camp on the best cell the UE performs the cell reselection procedure in the following cases:

– When the cell on which it is camping is no longer suitable– When the UE, in “camped normally” state, has found a better

neighbouring cell than the cell on which it is camping– When the UE is in limited service state on an acceptable cell

Cell Reselection Parameters

UE ranks available cells using R criteriaR(Serving) = Qmeas(s) + qHyst(s)R(Neighbour) = Qmeas(n) – qOffset(s,n)

Qmeas is the quality value of the received signal– Derived from the averaged received signal level for GSM cells– Derived from CPICH Ec/Io or CPICH RSCP for WCDMA cells

depending on the value of qualMeasQuantity (2, Ec/Io)

qHyst(s) = qHyst1 when ranking based on CPICH RSCP (4)qHyst(s) = qHyst2 when ranking based on CPICH Ec/Io (4)qOffset(s,n) = qOffset1sn when ranking based on CPICH RSCPqOffset(s,n) = qOffset2sn when ranking based on CPICH Ec/IoThe above two values are 0 for WCDMA cells and 7 for GSM cells

Cell Reselection Measurements

Serving cell

Neighbour 1

Neighbour 2

QHyst1

Qoffset1sn

3

2

1

tReselection

Measurement Quantity

ranking ranking ranking

2

1

21

3

3

Neighbour 1 is the new serving cell

Location and Routing Area updating

Location Area = The area to which the Core Network sends a paging message for circuit switched.

Routing Area = The area to which the Core Network sends a paging message for packet switched.

If the Location Area Identity (LAI) or Routing Area Identity (RAI) read on system information is different to the one stored on the USIM, the UE performs a LA or RA registration update

Three types of registration update– Normal– Periodic – according to T3212, T3312– IMSI attach/detach - used if att = 1 (1)

UE sends “attach” or “detach” messages when the UE is powered on or off

Paging

Two types of paging– Core Network informs a UE of a terminating service request – RAN informs all UE’s that the system information has been

modified

Paging messages sent to all UE’s in LA or RA – Discontinuous Reception: UE listens to PICH at predefined

times only– Discontinuous Reception (DRX) cycle = (2^k) * 10 (ms)

where k = cnDrxCycleLengthCs (7) for CS and cnDrxCycleLengthPs (7) for PS

Part 2 planning of 3G

Engineering

Transcript of Part 2 planning of 3G