WCDMA Features

and Tuning

Contents
Evolution to UMTS ................................................................ 3-9
UMTS Architecture Overview ............................................ 10-13
Idle mode features............................................................. 14-25
WCDMA Power Control and access.................................. 26-36
Admission and congestion control ..................................... 37-46
Handover .......................................................................... 47-68
WCDMA Channel Switching.............................................. 69-76
Radio planning optimization .............................................. 77-88
Quality of Service .............................................................. 89-96
Measurement and statistics collection ............................. 97-103
KPI ................................................................................ 104-106
Accessibility................................................................... 107-112
Retainability................................................................... 113-118
Integrity ......................................................................... 119-121
HSDPA-HSUPA ............................................................ 122-129

-2-

Module 1

Evolution to UMTS

-3-

Cellular Generation
Data

People talk about mob

technology in terms of
generations
1st Generation or 1G
2nd Generation or 2G
2.5G
3rd Generation or 3G
But what do these mean?
1978

1992

2000

2001

Progress of data rates with time and

generation

First Generation
1976+, though really the
technology of the 1980s
Analogue modulation
Frequency Division
Multiple Access
Voice traffic only
No inter-network roaming
possible
Insecure air interface

The 1st Generation of Cellular Technology

makes use of analogue modulation
techniques such as FM

-4-

Time

First Generation Planning

Macrocellular
High sites for coverage driven
planning
Antennas above roof height
Frequency planning required
For networks with more cells
than frequencies
Larger cell size
Order 30 km
Hard handover
Mobile only ever connected to a single cell
Cellular Networks are commonly represented as hexagon grids.
The above diagram shows how different frequencies are used in
different cells in a cellular network (different frequencies
represented by different colors).

Second Generation
1990s
1st system to use Digital modulation
Variety of Multiple Access strategies
Voice and low rate circuit
switched data
Same technology allows
international
roaming
Secure air interface

-5-

GSM Planning
Macrocells and microcells
Capacity driven planning
Frequency planning required
Optional parameters requiring
planning
Hierarchical Cell Structures
Frequency Hopping
Discontinuous Transmission
Power Control
Simple subscriber/traffic analysis
Capacity limited by number of
TRXs
Hard Handover
GSM networks use microcells to provide additional capacity.
Carrier Bandwidth = 200 kHz

CDMA one Planning

Macrocells and microcells
Single Frequency
Multiple frequencies for
hotspots
Soft Handover (multiple
connections between mobile
and network)
Code Planning
Capacity Interference Limited

1 connection
2 connection
3 connection

Unlike GSM there is no frequency planning required for

cdmaOne
However soft handover means that there are zones
where there are two/three connections to the network

-6-

2.5 G
Now
Digital modulation
Voice and intermediate rate
circuit/packet switched data
Same technology roaming
Secure air interface
Based upon existing dominant
standards such as GSM and
cdmaOne

2.5G technology are based upon existing 2G technologies

but are focused at increasing the maximum data rates
that the technologies can deliver

GPRS
General Packet Radio Service
Enhancement to the GSM standard
Utlilises
a) Multiple timeslots
b) Packet switching
Packet Switching Data typically to
rates of 56kbps
a) theoretically 171kbps for 8
Introduces serving GPRS support
node - SGSN

IS-95 B

Enhancement to cdmaOne standard

Utilises
High rate coding scheme
Combined code channels
Packet switching
Packet Switched Data to rates of 114 kbps

-7-

2.75 G EDGE
Enhanced Data for GSM Evolution
Sometimes called E-GPRS (Enhanced GPRS)
Enhancement to the GSM and TDMA standards
Utlilises:
8PSK Modulation
Possible 1.6 Mhz carrier under IS-136
8 Channel Coding Schemes
Multiple Timeslots (similar frame structure to GSM)
TDMA
Data up to rates of 384kbps (typically less)

3G Goals
Data Rates
Local area 2 Mbps
In office, stationary
Limited mobility 384 kbps
Urban pedestrian
Full mobility 144 kbps
Rural in car
High spectrum efficiency compared existing systems
High flexibility to introduce new services

3G Spectrum

-8-

UMTS FDD
Universal Mobile Telecommunication system Frequency
Division Duplexing Mode
Built onto enhanced GSM core network
Utilises:
QPSK modulation (Quadrature Phase Shift Keying)
Multiple channel coding and bearer rates
Variable spreading factors and multi-code transmission
CDMA
FDD
Asynchronous operation
Data up to rates of 2Mbps

UMTS TDD
Universal Mobile Telecommunication System Time Division
Duplexing Mode
Built onto enhanced GSM core network
Utilises:
QPSK modulation
Multiple channel coding and bearer rates
CDMA
TDD
Asynchronous operation
Data up to rates of 2Mbps

UMTS versus GSM

Carrier Spacing
Frequency Reuse
Factor
Power Control
Frequency
Quality Control

UMTS

GSM

5MHz

200kHZ

1-21

1500Hz

2Hz or lower

Radio Resource Management

Frequency Planning and
algorithms
Network Optimisation
Frequency Diversity 5MHz bandwidth gives multipath
Frequency Hopping
diversity with rake receiver
Packet Data
Load Based Packet Scheduling Time Slot based Scheduling
with GPRS
Transmit Diversity
Supported to improve downlink
Not supported by standard
capacity
but may be applied
-9-

Module 2

UMTS Architecture Overview

- 10 -

UMTS 3GPP reference

architecture

List of Acronyms
AUC:
AN:
BS:
BSC:
BSS:
BTS:
CN:
CSPDN:
EIR:
GGSN:
G4-SC:
HLR:
lMS Lp:
lSDN:
ME:
MGW:
MSC:
MT:
PDN:
PSPDN:
PSTN:
RNC:

Authentication Center
Access Network
Base Station
Base Station Controller
Base station Subsystem
Base Transceiver Station
Core Network
Circuit Switched Public Data Network
Equipment identity Register
Gatev4ay GPRS Support Node
Gateway MSC
Home Location Register
Multi Media Subsystem
Integrated Services Digital Network
Mobile Equipment
Media Gateway
Mobile Service Switching Center
Mobile Terminal
Packet Data Network
Packet switched Public Data Network
Public Switched Telephone Network
Radio Network controller
- 11 -

RNS:
Radio Network System
SCF:
Service Control Functionality
SCP:
Service Control Point
SGSN:
Serving GPRS Support Node
SlM:
Subscriber Identity-module
SMS-GMSC: Short Message Service GMSC
SMS-lWMSC: Short Message Service Interworking MSC
UE:
User Equipment
UMTS:
Universal Mobile Telecommunication System
USlM:
UMTS Subscriber Identity Module
UTRAN: UTMS RANRAN: Radio Access Network
RNS:
Radio Network Subsystem

Network Layers
Application Layer

Application

Application

Enabler
s

MS
C

SG

HLR/
HSS

SGS

Control
WCDMA
Access

GSM/EDGE
Access

SGS
N

Connectivity

MG
W

SG

IMS

GMSC
/TSC
PSTN
ISDN
MG
W
GGS
N

Radio Network Subsystem

A Radio Network Subsystem
consists of:
A single RNC
One or more Node Bs
Cells belonging to Node
Bs

- 12 -

Internet
Intranet

Radio Network Controller

Responsible for the use and
integrity of the radio resources
within the RNS
Responsible for the handover
decisions that require
signalling to the UE
Provides a combining / splitting
function to support macro
diversity between different
Node Bs

Iu
Iur

RNC

NODE
B

NODE
B

cel
l

cel
l

cel
l

cel
l

cel
l

cel
l
Uu

Node B

Iu

Logical node responsible for

radio transmission / reception
in one or more cells to/from
the UE
Dual mode Node B can
support FDD and TDD mode
Not necessarily a single site
according to the standards
Most current implementations
use a single site

Iur

RNC

NODE
B

NODE
B

cel
l

cel
l

cel
l

cel
l

cel
l

cel
l
Uu

Major interface in UMTS

There are four major new interfaces defined in UMTS

lu
The interface between UTRAN and the
CN
lu
The interface between different RNCs
lub
The interface between the Nobe B and
the RNC
Uu
The air interface
- 13 -

CN
lu
RCN
lub
Nobe
B
Uu
UE

lur

RCN

Module 3

Idle mode features

- 14 -

Idle Mode tasks

PLMN selection

Cell selection and reselection

LA and RA registration

Paging procedure

Reading system information

PLMN Selection (manual)

2
1
P
o
w
er
S
p
ec
tr
u
m
M
a

Strongest cell
8
6
4
2
0
-

0.

0.

0.

0.

1
1.
Frequen

1.

1.

1.
x 7

PLMN A
PLMN B
PLMN D
PLMN E

f1
f2

fn

1) The UE scans all RF channels in WCDMA and searches for the

strongest cell signal on each carrier.
2) The UE displays those PLMNs that are allowed as well as those
that are not allowed based on the strongest signal cell on each
frequency.
3) The user can select a PLMN manually from the list

Initial Cell Search

The Mobile searches for the strongest synchronization channel
(which is the same for every cell on the network).
Timing information from the Primary Synchronization Code is
used to detect the Secondary Synchronization Code.
The Secondary synchronization code gives information
regarding scrambling code and frame synchronization.

- 15 -

 The Synchronization code is time multiplexed with the

broadcast channel which gives information on Random Access
Codes available.

Initial Cell Search

P-SCH and S-SCH are time-multiplex with the Primary Common
Control Physical Channel P-CCPCH, which carriers the Broadcast
Channel.
P-SCH
256 chips
66.67 s

S-SCH
P-CCPCH

2560 chips
666.7 s
Data (18 bits)

Timeslot #0

2304 chips
600 s
Data (18 bits)

Timeslot #1

Data (18 bits)

27 kbps,
SF=256

Timeslot #2

The Cell Search Procedure

P-CCPCH
(PSC + SSC + BCH)
Initiate Cell Synchronization

UE monitors Primary SCH code, detects peak in matched filter output

Slot Synchronization Determined ----->
UE monitors Secondary SCH code, detects SCG and frame start time offset
Frame Synchronization and Code Group Determined ----->
UE determines Scrambling Code by correlating all possible codes in group
Scrambling Code Determined ----->

UE monitors and decodes BCH data

BCH data, Super-frame synchronization determined ----->

UE adjusts transmit timing to match timing of BS + 1.5 Chips

Cell Synchronization complete

- 16 -

The Cell Selection Criteria

Squal = Qqualmeas- qQualMin > 0

Srxlev = Qrxlevmeas qRxLevMin Pcompensation > 0

Where Pcompensation = max(maxTxPowerUL P;0)
qQualmin: sent in the broadcast information and indicates the
minimum required quality value. The UE measures the received
quality, Qqualmeas, on the CPICH (CPICH Ec/N0) and
calculates Squal.
qRxLevMin: sent the system information and indicates the
minimum required signal strength. The UE measures the
received signal Code Power (CPICH RSCP) and obtains Srxlev

Determination of Cell Selection

Criteria

qQualmin
qRxLevMin
UE max transm pwr Ul

CPICH

Qqualmeas
Qrxlevmeas

P-CCPCH

maxTxPowerful: the maximum transmission power

during random access on the RACH. Value sent in the

system information.
P: the UE maximum output power according to its
class

- 17 -

Cell Selection cases

The Cell Selection process is run when:
When the UE is switched on.
When the UE returns to Idle mode from connected mode
After a number of failed attempts of RRC connection request
when the UE is in idle mode and tries to establish a RRC
Connection.

Cell Reselection cases

The Cell Reselection process is run when:
When the cell on which it is camping is no longer suitable.
When the UE, in camped normally state, has found a better
neighboring cell than the cell on which it is camping.
When the UE is in limited service state on an acceptable cell.
When the EU triggers a cell reselation evaluation process, it
performs ranking of cells that fulfil the following criteria:

Squal > 0
Srxlev > 0

The Cell Reselection Evaluation

Process

- 18 -

Basis for Decisions on IntraFrequency Measurements

If Squal > sIntraSearch the UE does not need to perform intrafrequency measurements.
If Squal sIntraSearch the UE performs intra-frequency
measurements.
If the sIntraSearch is not sent to the serving cell, the UE
performs intra-frequency measurements.

Basis for Decisions on Interfrequency Measurements

If Squal > sInterSearch the UE does not need to perform inter

frequency measurements.
If Squal sInterSearch the UE performs inter frequency
measurements.
If the sInterSearch is not sent for the serving cell, the UE
performs inter frequency measurements.

Basis for Decisions on GSM

Measurements

If Squal > sRATSearch the UE does not need to perform

measurements on GSM cells.

If Squal sRATSearch the UE performs measurements on

GSM cells.
If sRATSearch is not sent for the serving cell, the UE
performs measurements on GSM cells.

- 19 -

Measurements According to
sRatSearch

InterRAT Cell Re-selection from a

WCDMA Cell to a GSM Cell

Location Registration

Three different types of registration updates:

Normal registration
Periodic Registration
IMSI attach/detach

- 20 -

Normal Registration

A Normal Registration update is done when:

The UE is switched on in a new LA or RA

The UE is moving into a new LA or RA
The UE is switching from connected to idle mode
The UE is unknown in the CN

Concepts of Mobility Management

In order to track the MSs, the cells (i.e., BTSs/Node Bs) in
GPRS/UMTS service area are partitioned into several groups.
To deliver services to an MS, the cells in the group covering the
MS will page the MS to establish the radio link.
In the CS domain, cells are partitioned into location areas (LAs).
The LA of an MS is tracked by the \/LR.
In the PS domain, the cells are partitioned into routing areas
(RAs). An RA is typically a subset of an LA. The RA of an MS is
tracked by the SGSN.
In GPRS, the SGSN also tracks the cell of an MS in PS
connection (i.e., when packets are delivered between the MS
and the SGSN).
In UMTS, the cells in an RA are further partitioned into UTRAN
RAs (URAs). The URA and the cell of an MS are tracked by the
UTRAN.

LA, RA, URA

- 21 -

Combined RA/LA update

Periodic Registration
UE in idle mode

UE moves to
connected mode

t3212

LA Update

UE moves to
idle mode

t3212

LA Update

LA Update

- 22 -

Paging a mobile: PCH

Paging information is carried on the paging channel, PCH, a

downlink common channel.
Each terminal is allocated a paging group.
Each group listens periodically to a Paging Indication Channel,
PICH.
How often a mobile must listen is governed by its paging group.
If the mobile was always on, battery life would be very short.

Paging

When the EU is in Idle mode, two different physical channels are

used in order to deliver proper information from the WCDMA RAN
to the UE: the PICH and the S-CCPCH (carries the PCH). The
PICH is used to indicate to the UE when it should read the SCCPCH and the PCH is used to carry the RRC message paging
type 1, which contains the actual paging information

Paging Indication Channels PICH

The PICH is used to inform the UE that it should listen to the

PCH
Fixed rate (SF=256, 30 kbps) so that 300 bits occupy a full
frame
N Paging Indicators {Pl0, , PlN-1} are transmitted in each
PICH frame, where N=18,36,72, or 144.
These are mapped into 300 bits of which 288 bits are defined

- 23 -

PICH

A 1 in the appropriate bit position indicates to the UE that it

should decode the next PCH (part of the secondary common
control physical channel) to see whether is a paging message
intended it.
PICH

Paging
Indicators
Paging Message

S-CCPCH

PICH

An idle mobile, will listen periodically to the PICH,

How often depends on the value of N.
If N = 144, the mobile will listen only 2 bits per frame.
This helps conserve the mobile battery.
However, the relevant PICH bits are repeated only once. Hence
a high quality radio channel is necessary

System information element

The System Information elements are broadcast in System

Information Blocks (SIBs). A SIB groups together System
Information elements related to the same kind of activity
controls.
Different types of SIB exist, and each type contains a specific
collection of information
A Master Information Block (MIB) gives reference to a number
of SIBs.
Master
Information
Block

System
Information
Block 1

System
Information
Block 2

- 24 -

System
Information
Block 3

Mapping of System Information

onto MIB and SIBS
Contents

MIB

PLMN Identity

Cell selection and

reselection
parameters
Paging parameters
Measurement
management
Celland common
channel
configuration
Timers and counters
in idle mode
Power Control on
common channel
Location and routing
updating

SIB1

SIB3

SIB5

SIB7

SIB11

SIB12

x
x
x
x
x
x

- 25 -

WCDMA Power Control

and access

- 26 -

Power control part of load control

Handover
Control
Power
Control

Load
Control

Admission
Control
Packet
Control

Power control
Objectives
Maintain the link quality in uplink and in downlink by
controlling the transmission powers
Prevents near-far effect
Minimize effects of fast and slow fading
Minimize interference in network
Accuracy of the power control is important
No time-frequency separation of users, all use the same
bandwidth
Inaccuracy in power control immediately lifts the networks
interference level, which correspondingly lowers the
capacity
Due to users mobility the speed of power control is also a
critical issue

- 27 -

Near-far problem in uplink

There can be large path loss difference between UE1 (cell
centre) and UE2 (cell edge)
lf both UEs are transmitting with the same power then UE1 will
block UE2 (and ether cell edge users tee)
Power control will drive transmission powers of UE1 and UE2 to
the minimum level that is required to meet OeS
In Node B received powers from UE1 and UE2 will be the same
for same services

UE1

UE2

Power Control
Power Control on the common channels ensures that their
coverage is sufficient both to set up UE-originating and UEterminating calls.
Power Control on the dedicated channels ensures an agreed
quality of connection in terms of Block Error Rate (BLER), while
minimizing the impact on other UEs.
Uplink Power Control increases the maximum number of
connections that can be served with the required Quality of
Service (QoS), while reducing both the interference and the
total amount of radiated power in the network.
Downlink Power Control minimizes the transmission power of
the NodeB and compensates for channel fading. Minimizing
transmitted power maximizes the downlink capacity.

- 28 -

WCDMA Power Control overview

The Physical Random Access

Channel

The PRACH consists of two parts

A preamble
To initiate access
A message
Which can contain a request for a dedicated
channel or a small packet of user data
2 frames = 20 ms
Message

PRACH
1 PRACH preamble = 4096 chips

1 PRACH slot = 2 normal timeslots

The PRACH Preamble

Selected from 1 of 16 defined preambles.

Each preamble has 16 bits. <1, -1>
The preamble is 4096 chips in length
The preamble is composed of 256 repetitions of 16 bits
The Power of the transmitted preamble is based on an estimate
of downlink loss from the received signal strength of the
common pilot channel, CPICH
- 29 -

The PRACH Preamble

The UE then randomly selects 1 timeslot from a limited number

over 2 frames (slotted ALOHAA).
Each timeslot is offset in time by a multiple of two timeslot
periods.
If no acknowledgement is received via the acquisition indicator
channel, AICH then UE reselects a time offset and increases
the power by 1dB and tries again.

Acquisition Indicator Channel AICH

The AICH indicates whether the PRACH preamble has been
received.
If the Node-B receives the preamble it mirrors the preamble
signature back on the AICH

Physical Random Access Channel

PRACH Message

The message is either 10 ms or 20 ms in length

Power level is set as per successful preamble
Data and control are CDMA multiplexed
The RACH can be used for packet data transmission
Messages can be used to update Location Area and Routing
Area information.
A channelisation code is allocated accordingly. The mobile is
informed of this on the Forward Access Channel.

- 30 -

RACH Preamble Ramping

Initial Downlink DPDCH Parameters

Downlink DPCCH Power

DPCCH power during TFCI = P_DL_DPDCH + pO1

PO1 = 0..6 dB in 0.25 dB steps (0 = 0, 1=0.25 24 = 6 dB):
default = 0 (0 dB)
DPCCH power during TPC = P_DL_DPDCH + pO2
PO2 = 0..6 dB in 0.25 dB steps (0 = 0, 1=0.25 24 = 6 dB):
default = 12 (3 dB)
DPCCH power during Pilot = P_DL_DPDCH + pO3
PO3 = 0..6 dB in 0.25 dB steps (0 = 0, 1=0.25 24 = 6 dB):
default = 12 (3 dB)

- 31 -

Initial uplink DPCCH Parameters

PC mechanism
Outer loop PC: RNC
Adjust the target SIR
In order to meet target
BLER

Fast PC: Nobe B

command terminal
To change transmit power
in order to meet target SIR

Outer loop power control

Inner loop power control

- 32 -

Received SIR

Uplink outer loop PC

The goal is to control the target SIR in order to remain the

wanted QoS with minimum transmit power
The target BLER is defined with the admission control algorithm
The uplink algorithm is controlled in RNC and downlink
algorithm in UE
Update frequency from 10 Hz up to 100 Hz
Outer loop power control will raise or lower the target SIR
according to step size, which is defined by radio network
planning.
The equipments performance defines the minimum value for
target SIR

Downlink outer loop PC

Implemented in UE to set SIR target on DL traffic channels

Quality target: BLER of each transport channel as set by RNC
Admission control determines the value of DL BLER
No SIR target change if Nobe B power reaches maximum or
network congestion occurs.

Uplink inner loop

Update rate I5 kHz => fast enougn to track and compensate

fast fading up to x km/n mobile speed
If received SIR > target SIR in Node B => UE is commanded to
decrease its transmit power. Similarly UE is commanded to
increase its transmission power if received SIR < target SIR
Network planning defines the step size. Usual step size values
are between 0.5dB and 2dB. n Soft handover:
UE can receive contradictory PC commands from different
node Bs
UE transmission power will be increased if all node Bs ask
for it and decreased if at least one node B demands it

Down link inner loop

Similar as DL fast PC:

UE measures SIR on DL DPCCH during the pilot period
UE maintains the QoS by sending fast power control
commands (TPC bits) requesting power adjustment
Power offsets can be used in DL in order to improve control
reliability. Offsets are network parameters that can be set in
planning phase
- 33 -

SIR parameter

Jump Regulator (Example)

SIRtarget = 4.9 + 1[-0/(1*199) + 1/1] dB =5.9 dB
SIRtarget = 5.9 + 1[-1/(1*199) + 0/1] dB =5.895 dB

SIRtarget
CRC = OK

ulInitSirTarget (speech = 4.9 dB)

CRC = NG

Transport block number

- 34 -

WCDMA Power Control Loops

Working Together (UL)

Setting Common Channel Powers

PCPICH: primaryCpichPower: default = 300(30 dBm)
Broadcast Channel: bchPower: default = -31 (-3.1 dB)
AICH: aichPower: default = -6 (-6 dB)
FACH (control): maxFach1Power: default =18 (1.8 dB)
FACH (traffic): maxFach2Power: default =15 (1.5 dB)
Paging channel: pchPower:default =-4 (-0.4 dB)
Paging indication ch: pichPower: default =-7 (-7 dB)
Primary SCH: schPower1: default =-18 (-1.8 dB)
Secondary SCH: schPower2: default =-35 (-3.5 dB)
HS-SCCH: hsScchMaxCodePwr: default =-2 (-2 dB)
E-AGCH: maxEagchPowerDl:default =-18.3 (-18.3 dB)
E-HICH/RGCH :maxUserEhichErgchPowerDl:
default = -18.3 (-18.3dB)

- 35 -

RBS
Node B

Downlink Power Drift During Soft

Handover
Power Drift

BS Power

BS Power

RNC

Down
Up
Up

Up

Node B

Node B

UE

Downlink Power Balancing

8 frame cycle
1...15 1...15 1...15 1...15 1...15 1...15 1...15 1...15

Drift corrected at start of next cycle

Reference value (average)

BS Power

SRNC

BS Power

UE

- 36 -

Admission and
congestion control

- 37 -

Admission control and packet

scheduler
Handover
Control
Power
Control

Load
Control

Admission
Control
Packet
Control

Nodes involvement
MS

Power Control

Node B

Power Control
Load Control

RNC

Power Control
Load Control
Handover Control
Admission Control
(also in SGSN)
Packet Scheduler

- 38 -

Congestion and Admission Control

Congestion/Load Controls general responsibility is to remain

the network in stable and prevent overloading
Congestion/Load control is in close co-operation with functions
of admission control and packet scheduler Load control
operates in RNC
Information of network
loading level
Loading status
NRT (Non-Real Time
traffic) load

Admission and Congestion Control

Admission control
If air interface loading is allowed to increase too much the
coverage of the cell will be reduced below the planned
value.
Admission control decides whether to accept the
terminals request for new radio access bearer by
calculating how much interference new bearer would
create to the cell in both UL and DL
Congestion control
Responsible of returning the network back into desired
target load in case of overload
Target load is set in network planning and overload
should be an exceptional situation

Admission Control
There are predefined UL and
DL thresholds for interference
power. Thresholds are set in
network planning.
If either UL or DL threshold is
exceeded the RAB is not
admitted.
For decision AC may derive the
transmitted bit rate, processing
gain, radio link initial quality
parameters, target BER, BLER,
Eb/No, SIR target.

- 39 -

Admission Control

Admission control: controls system load to maintain a sufficient

resources for urgent requirements and an acceptable service
quality for connected users.
Its based on following inpouts:
Downlink transmit carrier power
Air-interface Speech Equivalent (ASE) usage in uplink
and downlink
Spreading Factor usage
Code tree usage
Number of Compressed Mode radio links

Admission Control

ASE of a radio link = relative value, defined as the airinterface load relative to a speech radio link (l2.2kbps,
50% activity).
A radio link with an ASE of 3 in DL, is expected to
generate as much interference in downlink as 3 speech
radio links in the cell.
General method of estimating ASE value for a specific
service:
(maxrate radio link)
(activity factor radio link)
(maxrate radio link speech) (activity factor speech)

ASE values per connection type

Radio Connection Type
SRB
AMR 12.2
CS57.6
CS64
PS16/64 (Streaming)
PS16/128 (Streaming)
PS64/64
PS64/128
PS64/384
MultiRAB (speech+PS64/64)
MultiRAB (speech+PS0/0)
MultiRAB (CS64+PS8/8)
PS64/HS
PS384/HS

Uplink ASEs

2.43
1.61
7.22
11.10
4.74
4.74
8.32
8.32
8.32
9.32
1.61
12.48
8.32
40.27

- 40 -

Downlink ASEs

2.43
1.61
7.22
11.10
10.59
17.04
8.32
16.03
40.27
9.32
1.61
12.48
0.61
0.61

Admission Control

DL transmit carrier power: to keep sufficient power for UEs in

CM or experiencing a poor service quality due to fading
SF usage: Provides details about the number of codes of a
certain length that are in use. Limit the number of users of a
certain SF.
Code tree usage: Provides a measure for code tree usage in
the downlink. Monitoring of this dedicated resource based on
the tracking of the fraction on the downlink code tree in use.
Compressed mode radio links: Indication of the processor load
that the Compressed mode radio links causes in the node B.
Important due to hardware limitations in the Node B

Spreading Factor (SF) Limits Used

in Admission Control

Admission Control Workflow

- 41 -

Congestion Control

Main goal of the Congestion Control function = provide the ability

to solve overload situations.
Overloads occur due to a natural process caused by fluctuations in
the downlink power. Factors like fading, inter-cell interference, and
variations in the traffic on individual connections can cause these
fluctuations.
Congestion Control is triggered only in the case of (near) overload
in a cell.
Congestion control based on 3 consecutive steps:
1. Restricts admission
2. Delay packet transmission, by reducing the packet bit rate
3. lf this does not solve the congested situation, it releases
radio links until congestion ceases

Soft Congestion Mechanism

Example
New request for non granted 64/128, non granted 64/64 or granted access

Admission Control blocks the new request

An existing ng user of 64/384 will be switched down to 64/128

or an existing ng user of 64/128 will be switched down to 64/64

- 42 -

Congestion Control
Core Network
lu

SRNC
& RNC

lu

SRNC
lur

Over lu:
1.
3.

5.

Over lur:

Best Effort users in HO

Best Effort users

2.

CS users in HO
CS users

Best Effort users in HO

Best Effort users

4.

Speech users in HO
Speech users

CS users in HO
CS users

6.

Speech users in HO
Speech users

Congestion control: ASE release order

Detection of DL Cell Congestion

Due to Transmitted Power

- 43 -

Packet scheduler

Determines the available radio resources for Non-Real Time

traffic (NRT) radio bearers
Share the available radio resources between NRT radio bearers
Monitor the allocations for NRT radio bearers.
Initiate the switching between common, shared and dedicated
channels when necessary.
Monitor the system loading.
Performer load control actions for the NRT radio bearers when
necessary

Packet Scheduler

Capacity can be divided between non-controllable and

controllable traffic
Load caused by real time traffic, interference from other cell
users and noise together is called non-controllable load
The part of the available capacity that is not used for noncontrollable load can be used for NRT radio bearers on best
effort basis (=controllable load)
PS is implemented for dedicated as well as common control
transport channels.
PS takes care of filling the controllable capacity with NRT traffic

load

Planned target load

Free capacity, which can be

allocated for controllable
load on best effort basis

Non-controllable load

time
The amount of scheduled capacity depends on:
UE and BTS capabilities,
the current load in the cell,
the availability of -physical
resources.
44 -

Measurement for WCDMA Packet

Scheduler

Packet Scheduler
For dimensioning purposes radio network planning can
define packet access features per, e.g. by next parameters
Amount of packet bursts per session
Reading time between bursts
Size of packets
Arrival rate packets
Amount of packets per burst
Number of retransmission
Packet service session
Packet call

time

Reading
time

Packet size

Packet arrival interval

- 45 -

Control summary

- 46 -

Handover

- 47 -

Admission control and packet

scheduler
Handover
Control
Power
Control

Load
Control

Admission
Control
Packet
Control

Handover types in WCDMA

UMTS-Handover

Intra-system
Handover

Intra-frequency
Handover

Inter-system
Handover

Inter-frequency
Handover

UMTS<>GSM

UMTS<>EDGE

etc.
UMTS<>GPRS
Soft

Softer

Hard

Hard

- 48 -

WCDMA Handover control

Hard HO (HHO)
All the old radio links of an UE are released before the new
radio links are established.
Real time bearers: short disconnection in transmission.
Non real time bearers: HHO is lossless.
Shared & common channels used for hard handover (cell
reselection)
Soft HO (SHO).
MS always keeps at least one radio link to UTRAN.
Soft HO: MS is simultaneouslly controlled by two or
more cells belonging to different BTS of the same R C
or to different RNC.
Softer HO. MS is controlled by at least two cells under
one BTS.
Dedicated channels (Cell_DCH state) used for SHO
Handover can be either network or UE initiated
Serving RNC makes the decisions in both cases

WCDMA Handover control

- 49 -

Hard handovers

Intra & Inter-frequency HHOs

Usually triggered to maintain mobility
Not recommended in WCDMA unless there is an urgent need,
because
Hard HO increase interference easily, since the real-time
user is disconnected temporarily and the used power
must be re-evalueted
This decreases the capacity in heavy traffic situations and
can worsen the near-far effect
Absence of lur (connection between RNCs) will cause hard
HOs
Compressed mode used in HOs between carriers and systems
In compressed mode UE stop UL transmission for few
milliseconds within a radio frame (10ms) in order to
enable measurements of different carriers/systems

Received Power Without Soft

Handover

UE responding to
BS1

UE responding to
BS2

BS1 Receive Power

Target

tim
BS2 Receive Power
Target

tim
Trouble zone: Prior to Hard
Handover,

- 50 -

Received Power with Soft Handover

Inter frequency handover

IFHO can be used planning to

provide coverage (micro
macro cell)
provide capacity (reduce cell loading)
2nd carrier can be enable on cell basis
Not so straightforward to perform in UE due to need of
compressed mode
Most Network vendors equipment supports IFHO
IFHO is generally seen as a means of optimisation as the traffic
evolves, but can be used also e.g. to provide indoor coverage

Soft Handover (SHO)

SHO helps avoid near-far effect for real-time connection

For high mobility users shadow fading + (slow) hard handovers
would create near-far situations
SHO is an essential interference mitigation tool in WCDMA

- 51 -

Soft Handover
BS
SHO utilises two separate codes in DL (RAKE fingers in UE are
assigned for reception)
Maximum ratio combining done in UE for the signals
Produced gain 1-3 dB, handover..
Gain depends on the difference of the signals strength
Gain depends on channel conditions and accuracy of the
received channel estimate
In some circumstances the
gain can be lost!
The more multipath diversity is available the less SHO gain is
achived

Soft Handover Diversity Gain in the

Downlink

- 52 -

Softer/Soft Handover
BS
UPLINK
More complex situation than in DL
During softer HO, same procedure in node Bs RAKE than in
DL case
Produced gain 1-3 dB
Better performance in terms of strength differences,
since the signals come from the same source
During Soft HO, the combining of signals is done in the RNC
Selection combining performed for baseband signal
Based on selecting the frame with better FER or BER
Better frame send to be used in open loop PC (target
SIR estimation)
Gain achieved through more stable UE tx-powers (12dB) No actual gain to the radio link

Soft Handover Diversity Gain in the

Uplink
Good block

RNC

CN

Block in error

- 53 -

Soft Handover

The cells in a WCDMA RAN are, from UE point of view, divided in

different mutual excluding sets defined by 3GPP:
Active Set
The cells involved in soft handover and measured by
the UE
Monitored Set
The cells only measured by the UE and not part of the
Active Set. The monitored set can consist of intrafrequency, Inter-Frequency and Inter-RAT
The cells measured by the UE are the sum of the Active Set
and the Monitored Set.
The number of Intra-frequency cells in the Monitored Set +
the Active Set cells is limited by 3GPP to 32.
The number of Inter-Frequency cells in the Monitored set is
limited to 32.

Soft Handover
Active Set
As UE moves, node Bs are continuously added to and
removed from the active set. When added, they are also
updated to the neighbor cell list.
UE measures the monitored set of cells and Handover
Control evaluates ifany node B should be added to, removed
from or replaced in the active set
Maximum Active Set Size parameter
is used to determine the maximum allowed number of
SHO connections (varies between 1-5, typical default 3)
Too high value decreases capacity (signalling
increases and multiple connections occur too
often)
Too low value degreases the SHO performance
(best candidate cells may be excluded in some
situations)

- 54 -

Signaling Flow When Changing the

Active Set
RNC

UE
MEASUREMENT CONTROL message
(DCCH)

Perform
Measurement
MEASUREMENT REPORT message
(DCCH)

UE Evaluation

RNC Evaluation
Execution

Radio Link Addition

ACTIVE SET UPDATE
(DCCH)

Radio Link Removal

ACTIVE SET
UPDATE COMPLETE

Radio Link
Add/Remove/Replace

RNC Evaluation
MEASUREMENT CONTROL message
(DCCH)

The MEASUREMENT CONTROL

Message
Content
Measurement type

Description
Intra-frequency, Inter-frequency or Inter-RAT

Measurement identity
number

A reference number used by the WCDMA RAN when

modifying or releasing the measurement and by the UE in the
Measurement Report.

Measurement
command

Setup: Sets up a new measurement.

Modify: Modifies a measurement, e.g. to change the reporting
criteria Release: Stops the measurements and clears related
information.

Measurement objects

The cells the UE shall measure on.

IE: IndividualOffset:
An offset can be assigned to each cell. It can be either positive
or negative and is added to the measurement quantity before
the UE evaluates whether or not a so-called event has
occurred.
CPICH Ec/No and/or RSCP (Received Signal Code Power)

Measurement quantity
Measurement reporting
criteria
Reporting mode

The triggering for MEASUREMENT REPORT

Specifies whether the UE will transmit the MEASUREMENT
REPORT using acknowledge or unacknowledged data transfer
of RLC

- 55 -

Soft Handover

The handover measurements for Intra-Frequency HO are based

on P-CPICH Ec/No

Ec/No is the received signal code power divided by the total

received power. It is calculated from signal before the signal despreading operation while Eb/No is calculated after despreading.
Ec/No can be determined for the signal "in the air
Eb/No depends on the service (bit rate, CS or PS, receiving
end) and Ec/No is service independent
The accuracy of the Ec/No measurements is essential for HO
performance
Depends on filtering lenght and mobile speed
Filter length for slowly moving & stationary UEs
should be just long enough to avoid Fast Fading
errors
Too long filter length for will cause HO delays to fast
moving UE

Ec/No and Eb/No

SNR can be thought of as the signal to noise ratio at the input to

the receiver (also known as Ec/No).
Eb/No can be thought of as the signal to noise ratio delivered to
the user.

- 56 -

Ec/No and RSCP

CPICH-Ec/No: received energy per chip divided by the power

density in the band.
CPICH-RSCP: Received Signal Code Power.
RSSI: Received Signal Strength Indicator
Two parameters (Ec/No & RSCP) to verify P-CPICH detection
to minimise coverage holes,
Ex: RSCP >-100dBm (sufficient) & Ec/No > -14 (suficient)
By correlation between low Ec/No & high RSCP interferences &
pilot pollution can be found

Soft Handover

Event based triggered measurements and reporting

Basic reporting events 1A, 1B and 1C (Ref. 3GPP)
1A: Primary CPICH enters the reporting range
1B: P-CPICH leaves the reporting range
1C: Non-active P-CPICH becomes better than an
active P-CPICH
1D: Change of current best cell with new P-CPICH
Handover decision
Done by RNC based on measurements and available
resources

Reporting Event 1a and 1b (Add and

Delete)

- 57 -

Reporting of Event 1c (Replace)

Measurement
quantity

measQuantity1
(Ec/No or RSCP)

P_CPICH 1
P_CPICH 2
P_CPICH 3

hyst1c/2
hyst1c/2

P_CPICH 4

time

timeToTrigger1c

Example:
maxActiveSet=3

Reporting of Event 1d (Change of

Best Cell)
Measurement
quantity

P_CPICH 1
P_CPICH 2
Hysteresis1d/2
Hysteresis1d/2

P_CPICH 3

time
timeToTrigger1d

- 58 -

Inter-Frequency HO, Inter-RAT HO

General
The handovers can be triggered due to Ec/No criteria or RSCP
criteria.
The handovers are also triggered by UE Tx power.
fddGSMHOSupp: Indicates if the RNC supports Inter-RAT HO
fddIFHOSupp: Indicates if the RNC supports Inter-Frequency
HO
hOType: Parameter set per cell. Indicates if Inter-RAT Ho or
Inter-Frequency HO or none shall be evaluated in case both
Inter-RAT and Inter-Frequency neighboring cells have been
configured.
hOTypeDRNCBand: Parameter set per frequency band.
Indicates for a SRNC if Inter-RAT HO or Inter-frequencyHandover shall be evaluated per frequency band in case both
Inter-RAT and Inter-frequency neighboring cells have been
configured in the Destination RNC.

Inter-Frequency Handover
Sequence
RNC

UE
MEASUREMENT CONTROL message
(start event 2b)

Perform
Measurement

RNC Evaluation

MEASUREMENT REPORT message

(event 2b)

UE Evaluation

Execution
Radio Link
Setup/Addition

Radio Link Release

RNC Evaluation

Physical Channel Reconfiguration

Physical Channel
Reconfiguration Complete

Physical Channel
Reconfiguration

Measurement Control
(updated neighbor

Measurement Control (stop-event 2b)

- 59 -

Simplified WCDMA to GSM Intersystem handover message flow

UE

UTRA
N

GERA
N

Measurement control for WCDMA quality monitoring

WCDMA quality measurement report (Q<Tresh)

Compressed Mode pattern activation

Measure
GSM/GPRS

Measurement control for GSM/GPRS measurement

GSM/GPRS quality measurement report

Inter-system handover/cell change order from UTRAN

Execute
ISHO

UE communicate with GSM/GPRS

Handover from WCDMA to GSM

MT

UTRAN

CN

BSS

Measurement report
Relocation required
(Inter-RAT handover info)

Handover from UTRAN

command (Handover
command)

Relocation command
(Handover command)

Handover request
(Inter-RAT handover info)
Handover request ack
(Handover command)

Handover access
Handover access
Handover detect
Handover complete
lu release command
lu release complete

- 60 -

Handover complete

Handover from GSM to WCDMA

MT

UTRAN

CN

BSS

Measurement Information
Measurement report
Relocation request
Relocation request
acknowledge (Handover
to UTRAN command)

Handover required
Handover command
(handover to UTRAN
command)

Inter-system to UTRAN handover command

(handover to UTRAN command)
Physical layer
synchronisation
Handover to UTRAN
complete

Relocation detect

Relocation detect

Clear command
Clear complete

Event 2 for Inter-Frequency HO,

Inter-RAT HO
Event 2a: Change of Best Frequency
Event 2b: The estimated quality of the currently used frequency is
below a certain threshold and the estimated quality of a non-used
frequency is above a certain threshold
Event 2c: The estimated quality of a non-used frequency is above
a certain threshold
Event 2d: The estimated quality of the currently used frequency is
below a certain threshold
Event 2e: The estimated quality of a non-used frequency is below
a certain threshold
Event 2f: The estimated quality of the currently used frequency is
above a certain threshold

- 61 -

Event 3 for Inter-RAT HO

Event 3a: The estimated quality of the currently used UTRAN
frequency below a certain threshold and the estimated quality of
other systemfrequency is above a certain threshold
Event 3b: The estimated quality of other systems frequency is
below a certain threshold
Event 3c: The estimated quality of other systems frequency is
above a certain threshold

Reporting Event 2d,2f and 3a

(interRAT)

- 62 -

Reporting Event 2d,2f and 2b (InterFrequency)

GSM to WCDMA HO :
Measurements on WCDMA Cells
Four different scenarios:

WCDMA RAN neighbor cells are measured only when the

signal strength of the GSM serving cell is above the
threshold set by QSI and QSC.

WCDMA RAN neighbor cells are measured only when the

signal strength of the GSM serving cell is below the threshold
set by QSI and QSC.

WCDMA RAN neighbor cells are always measured.

WCDMA RAN neighbor cells are never measured.

This can be used to turn off the cell reselection/handover to
WCDMA, per cell, even if COEXUMTS (parameter used to
activate the functionality of making handovers and cell
reselections between GSM and WCDMA) is on for the BSC.

Measurements on UTRAN Cells

- 63 -

The parameter QSI and QSC controls when

measurements on UTRAN neighboring cells shall be
performed. This is used to:
avoid unnecessary measurements
optimize the Multi-RAT MS battery consumption
QSI is used for Circuit Switched idle and Packet Switched
modes (send on BCCH or PBCCH)
QSC is used for active mode (send on SACCH)
Before QSC is known after changing to active mode,
the parameter QSCI controls it measurements should
be performed according to QSI (QSCI=0) or always
(QSCI=1) until QSC is received

Settings of QSI and QSC

QSI and QSC can be set to:

0 6: below 98 dBm to 74 dBm in steps of 4 dBm.

7:

always.

8 14:
15:

above 78 dBm to 54 dBm in steps of 4 dBm.

never.

WCDMA Cells Measurements.

Example: QSI(QSC) = 5

- 64 -

WCDMA Cells Measurements.

Example: QSI(QSC) = 11

Parameters Used in IRAT from

GPRS to WCDMA
Measurement
Quantity

CPICH RSCP
CPICH Ec/No

FDDQOFF
FDDQMIN
5 seconds
CPICH Ec/No
> FDDQMIN

IRAT to
WCDMA

CPICH RSCP >

GSM RLA+ FDDQOFF

- 65 -

GSM RLA

The Handover Algorithm BSC

(Locating Algorithm)

WCDMA Cell
measurement
Filtering
Urgency condition

B
Inter System Handover
algorithm
ISHOLEV = 20 %

% idle TS
ISHOLEV

Basic ranking

% idle TS: 1/6 16, 7%

Traffic load

Ec/No
> MRSL

Add WCDMA cell

to candidate list

Radio Network functions

evaluations

Organizing the list

Sending the list
Allocation reply

HO related topics in network

planning
Network topology: How sites are located relative to each other,
how many sectors/site
Node B antenna radiation patterns
Overlapping patterns => more softer HOs
Antenna tilt => Number of potential Node Bs in Active Set
Path loss and shadow fading characteristics
The average number of Node Bs that a UE can synchronise to
HO parameter adjustments is part of the network optimization

- 66 -

Load Sharing Capabilities Available

in the WCDMA RAN
Directed Retry
to GSM

WCDMA RAN

Inter Frequency
Load sharing

Carrier 1
Carrier 2

GSM RAN

Inter-Frequency Load Sharing

Inter-Frequency Load Sharing
At call set-up - RRC Connection Establishment for all
RABs
Triggered by Downlink Transmitted Carrier Power
The feature is activated in an RNC by setting the
parameter loadSharingRrcEnabled to TRUE
The attribute loadSharingCandidate TRUE/FALSE
specifies whether the target cell is a load-sharing neighbor
of the source cell

f1

f2

f2

f1

f1

- 67 -

f1

Directed Retry to GSM

Applicable for Voice

GSM

Admission
Control

WCDM
A

Directed Retry to GSM

Directed retry to GSM

At call set-up - RAB Establishment for voice
Triggered by Downlink Transmitted Carrier Power
The feature is activated in an RNC by setting the parameter
loadSharingDirRetryEnabled to TRUE
One GSM target can be defined for each WCDMA cell via the
cell parameter directedRetryTarget
LoadSharingGsmThreshold specifies the minimum load at
which off-loading to GSM begins: ex 80% of pwrAdm
LoadSharingGsmFraction specifies the percentage of Directed
Retry candidates to be diverted to GSM while the cell load is
above the specified load threshold

Load Balancing for Voice Between

WCDMA-GSM

- 68 -

WCDMA Channel
Switching

- 69 -

Basics

In WCDMA there are different types of channels that can be used

to carry data in order to maximize the total traffic throughput. The
two most basic ones are common channels and dedicated
channels. Channel type switching functionality is used to move
subscribers between the common and the dedicated channel,
depending on how much information the subscriber needs to
transmit.

Transmission on
Common/Dedicated channels
Common physical channel (RACH, FACH)

Efficient use of radio resources

Closed loop TPC cannot be applied

Rx
power

Suitable for light traffic

Time

Dedicated physical channel (DPCH)

Closed loop TPC can be applied Radio
resource are monopolized Pilot symbols
and TPC bits must be transmitted every
time

Rx
power

Time

Suitable for heavy traffic

Heterogeneous channel pools

Channel Rate
Switching

Dedicated
Channel

Channel
Type
Switching

- 70 -

Shared
Channel

Radio Channels

Logical Channels

DTCH (Dedicated Traffic Channel)

Transfers user information to 1 User Equipment (UE).
DCCH (Dedicated Control Channel)
Transfers control information to 1 User Equipment (UE).
CTCH (Common Traffic Channel)
Transfers user information to all or group User Equipment
(UEs).
PCCH (Paging Channel)
Transfers paging information.
BCCH (Broadcast Channel)
For broadcast system control information.
CCCH (Common Control Channel)
Transfers control information between network end User
Equipments.

- 71 -

Transport Channels

DCH (Dedicated Channel)

Transfers user or control information between the network
and the UE.
RACH (Random Access Channel)
Transfers control information from a UE.
CPCH (Common Packet Channel)
Transfers packet-based user data, it is an extension of
RACH.
BCH (Broadcast Channel)
Broadcasts system and cell specific information.
FACH (Forward Access Channel)
Transfers control information to a UE.
PCH (Paging Channel)
Transfers paging information a UE.
DSCH (Downlink Shared Channel)
Transfers dedicated control or traffic data, it can shared
several users.

Physical Channels

DPDCH (Dedicated Physical Data Channel)

Transfers dedicated data generated at layer 2 and above.
DPCCH (Dedicated Physical Control Channel)
Transfers control information generated at layer 1.
DPCH (Downlink Dedicated Physical Channel)
Transfers control information to a UE.
PRACH (Physical Random Access Channel)
Transfers the RACH.
PCPCH (Physical Common Packet Channel)
Transfers the CPCH.
PCCPCH (Primary Common Control Physical Channel)
Transfers the BCH.
SCCPCH (Secondary Common Control Physical Channel)
Transfers FACH and PCH.
PDSCH (Physical Downlink Shared Channel)
Transfers DSCH.
CPICH (Common Pilot Channel)
Supplies down physical channel default phase.
SCH (Synchrcnization Channel)
Used for cell search.

- 72 -

Physical Channels

PICH (Page Indication Channel)

Transfers the page indication.
AICH (Acquisition Indication Channel)
Transfers acquisition indicator for PR.-\CH access.
AP-AICH (Access Preamble Acquisition lndication Channel}
Transfers acquisition indicator for PCPCH access.
CD/CA-ICH (CPCH Collision DetectionrCha.nnel Assignment
Indicator Channel)
Used for collision control of PCPCH.
CSICH (CPCH Status Indicator Channel}
Transfers status information of PCPCH.

Channel Switching - example

Single RAB state transitions

Dedicated to Common (cell_DCH to cell_FACH)

Common to Dedicated ( cell_FACH to Cell_DCH 64/64, 64/HS,
EUL/HS)
Common to URA_PCH (cell_FACH to URA_PCH)
URA_PCH to Common (URA_PCH to Cell_FACH)
URA_PCH to IDLE
Dedicated to Dedicated single RAB (cell_DCH to cell_DCH)

- 73 -

Channel Switching Algorithms

Common to dedicated evaluation

This algorithm monitors whether a switch from the common
transport channels FACH/RACH to a higher bit rate dedicated
transport channel is required, due to a large amount of user
data buffered in the RNC or the UE.
Dedicated to common evaluation
This algorithm monitors whether a switch from a dedicated
transport channel to the common transport channels
FACH/RACH is required, due to a decrease in transmitted user
data.
Common to URA evaluation
This algorithm releases UEs with no activity in order to free
resources and decrease the power consumption of the UE
URA to idle evaluation
This algorithm requests a switch to Idle mode if a UE has been
allocated to URA_PCH state for a certain time interval.

Channel Switching Algorithms

Coverage triggered down-switch evaluation

The coverage triggered down-switch evaluation algorithm
monitors whether a switch to a lower rate dedicated channel is
required due to coverage reasons.
A down-switch is requested if all legs in the AS use a
Transmitted Code Power close to the max allowed code power.

Dedicated to dedicated up-switch evaluation

Monitors UL & DL throughput and DL Transmitted Code Power
An up-switch is requested if the throughput exceeds a threshold
and if all radiolinks in the AS is able to provide the power
required for the next higher bit rate radio bearer.

- 74 -

Channel Switching-Common to
Dedicated
RLC buffer size (bytes)
(UL/DL)

dlRlcBufUpswitch
or
ulRlcBufUpswitch

Timer
starts

Time
(s)

Timer
expires

The Dedicated to Common Channel

Switching Evaluation
Throughput (kbps)
(UL/DL)

downswitchTimerThreshold

downswitchThreshold

downswitchTimer

downswitchTimer stops
No downswitch

downswitchTimer starts

Time
(s)

Downswitch request
issued

Coverage Triggered Down-switch

Transmitted DL Code

Cell A

Max Code Power

downswitchPowerMargi
n

Power alarm threshold

Downswitch
coverageTime
r

- 75 -

Throughput based Downswitch

DL
throughput

Next lower rate

dlDownswitchBandwidthMargin
dlThroughputDownswitchTime

Downswith request
executed

- 76 -

Radio planning
optimization

- 77 -

Antenna height

Since WCDMA performance is interference limited the cell

dominance areas should be kept as controlled as possible
lf the antenna is located too high (no proper tilting) then
The cell gathers more traffic and external interference and
thus the effective capacity is decreased
Produced interference decreases the capacity of the
surrounding network
Also surrounding networks service probability is
negatively effected

Antenna azimuth

Natural obstacles and buildings should be used to create good

dominance areas for WCDMA cells
This improves the SHO performance and decrease interference
Example of a UMTS
cell, that is naturally
bordered (wall effect) by
buildings

Antenna height simulation

When re-using the GSM sites, analysis should be made

whether the UMTS antennas should be positioned lower
This analysis is done with simulations and visiting the site
locations in practise
Part of network reused few
+40meter GSM antenna heights

High UMTS antenna positions

lowered to 25-35m

Dominance areas become

clear, so less interference
is introduced and HO
performance is better.
Capacity is increased
and performance
enhanced!

- 78 -

Antenna tilt

ln addition to antenna height, downtilting is very important

physical means for interference minimizing in WCDMA
Basic rule of designing antenna tilt is that the height of the
antenna should be selected with respect to the wanted amount
of cell range
If the cell range with respect to available antennas and their
tilting with a feasible amount of tx-power becomes too large to
suit the network plan, then the antenna must be lowered
According to experience, the analysis should start with the
optimum tilting and not by reducing the tx-powers of the cell,
which can be optimized after the tiltings are done
Horizontal plane
h

Antenna tilt

According to experience even 15 degrees of downtilting is not

impossible (lf the radiation pattern of the antenna supports it),
although in practice not very often needed.

There has also been lot of

discussion of a potential need
to change the tilts often during
the network lifecycle (even
regularly)
However practice have not
shown such need if the tilts are
design well from the start with
help from simulations
But once WCDMA gets
congested this might be given
another look (Remote tilts).

- 79 -

Sectorisation

According to simulations and analysis, sectorisation of WCDMA

site helps to improve capacity of the network
However, as permissions for additional antennas are quite hard
to come by, e.g. 6-sector sites might be very rare

Sectorisation can
increase the capacity
if correct beamwidth
antennas are selected
and SHO properly
controlled

Antenna 3 Other to own

dB
cell
Beam
interference
width
ratio, i

Served
users

Soft
handover
overhead

UL coverage
probability
(outdoor to
indoor)
For 8/64/144
kbps

OMNI CASE
Omni

0.79

1200
900
650

1.33
1.19
0.88

1200
900
650
330

1.72
1.49
1.09
0.92

240

28%

70/32/40%

THREE SECTORS CASE

441
461
575

39%
35%
34%

85/50/59%
87/55/62%
86/59/62%

FOUR SECTOR CASE

489
510
604
691

54%
51%
41%
40%

90/62/68%
92/67/72%
92/70/71%
88/65/64%

SIX SECTOR CASE

120
900
650
330

2.18
1.97
1.43
1.15

593
627
758
880

64%
59%
55%
48%

95/75/79%
96/80/82%
96/80/81%
93/76/76%

Served
users in
DL

UL coverage
probability
(outdoor to
indoor) for
8/64/144 hbps

Master head amplifier

The MHA can be used
in WCDMA in the
uplink direction to
compensate for the
cable losses and thus
reducing the required
mobile stations
transmit powers
Using MHA the
performance in uplink
can be improved also
in WCDMA systems.
However in practice if
the network turns to
downlink limited then
the MHA wont help

Other to
Served
own cell
users in
interference
UL
ratio, I

THREE SECTORED CASE, 65O antenna

No MHA
With MHA

0.60
0.61

1038
1064

807
746

93/78/78%
95/82/82%

FOUR SECTTORED CASE, 65O antenna

No MHA
With MHA

0.73
0.73

1089
1107

884
846

96/86/85%
98/89/89%

SIX SECTORED CASE, 33O antenna

no MHA
with MHA
No MHA
4dB cable
losses
WITH mha
4 DbN
CABLE
LOSSES

- 80 -

0.88
0.90

1124
1132

1052
1021

97/87/86%
98/90/90%

0.88

1109

1057

95/83/82%

0.90

1132

1016

98/90/90%

Master head amplifier

Increases uplink coverage/capacity in low loaded network

Compensates for feeder and combiner losses in the uplink
direction, increasing coverage for suburban, rural and road sites
where antennas are in very high positions and the feeder lines
are long
Allows UEs to reduce transmission power level
With heavily loaded network (i.e. high interference) the benefit
of the mast head amplifier is negligible
Also in downlink limited 3G networks (DL oriented traffic, users
in cell edge, DL tx-power per user low e.g. in for high bit rate
indoor users) the usage of mast head amplifier is not justified
Needs extra space in the masts and increase the wind load

MHA is sometimes called as

Tower Mounted Amplifier
(TMA)

Transmit power increase

- 81 -

Transmission powers

Default transmission powers are determined by the equipment

vendors.
In initial phase of the planning
Transmission powers of TCHs and CCHs needs to be set
Maximum UE transmission power is to be defined
In DL the power tuning between TCHs and CCHs has effect on
network performance
More power to CCHs > better channel estimation, which
improves the Eb/No performance and thus improves
coverage
More power to TCHs > better capacity
Rule of thumb: 15-20% of DL total power is used for
CCHs
Maximum UE transmission power should be set to 21-24 dBm
(network operation and battery life)
Most important control channel is the common pilot channel
(CPICH)

Transmission powers

Also other control channels beside CPICH need power (for

example BCH) to enable correct functioning of the system
All the other common control channels are powered in relation
to the P-CPICH
The goal of allocating power to the common channels is to find
a minimum power level needed for each channel to secure the
network operation and to provide the same cell coverage area
as with CPICH, but not to waste any capacity left for the traffic
channels.

Typical DL power recommendations

Channel

Allocated power

Max power of the Node B

43 dBm

CPICH

Max power-10dB

PCH

Max power-11 -13 dB

SCH

Max power-11 12dB

FACH

Max power-12-13dB

BCH

Max power-11 13dB

- 82 -

Recall: Some control channels

PCH: Paging channel initiates the communication from network

side
SCH: Synchronization channel
FACH: Forward access channel carries control information to
terminals that are known to be located in the given cell. ls used
to answer to the UL RACH message.
BCH: Broadcast channel carries network specific information to
the given cell (random access slots for UL, antenna
configuration etc)
PICH: Paging indicator channel is used to provide sleep mode
operation for UE
AICH: Acquisition indicator channel is used to indicate the
reception of RACH
CCPCH: Primary and secondary common control physical
channels (P-CCPCH and S-CCPCH) are physical channels that
carry BCH, FACH and PCH.

Transmission powers

P-CCPCH transmitted with activity factor 0,9

S-CCPCH transmitted with activity factor 0,25
SCHs transmitted with activity factor 0,1
AICH, PICH and CPICH are transmitted continuously

The BCH is transmitted on the P-CCPCH and FACH and PCH

on the S-CCPCH
The BCH is transmitted on the P-CCPCH continuously expect
during the 256 first chips, when the P-SCH and S-SCh are
transmitted we can assume 0,1 activity factor for the SCHs and
0,9 for the P-CCPCH
Channel

Allocated power

Power out of the

total common
channel powers

Power out of the maximum

Node B transmission power
(20W)

P-SCH

0,331W

S-SCH

0,224W

PICH

0,1W

AICH

0,126W

P-CCPCH

0,245W

S-CCPCH

1,165W

CPICH

1W

31%

5%

All common ch.

3,191W

100%

16%

- 83 -

Carrier addition

Adding a carrier to less transmit power per carrier, if no

additional PA is installed
Additional carrier can also be used for e.g. optimisation of
indoor coverage with clever network planning and
parametrisation (not with power reduction)
Even with less transmit power, there is a capacity gain possible
especially for high traffic areas (low cell range)
Actual gain produced is heavily dependent on the traffic
mix
Carrier
configuration
1C>2C
2C>3C

Dense
Urban
350m
92%
41%

DL Capacity gain
Urban
Suburban
550m
1700m
87%
37%

77%
27%

Rural
7km
60%
15%

Indoor coverage aspects

Most of the UMTS users are indoors.
Therefore good indoor coverage is vital
for UMTS success
In GSM indoor coverage is pretty
straightforward to plan. However this is
not the case with WCDMA
Indoor coverage provided from outdoor base stations is
highly sensitive to cell load increase in WCDMA
If outdoor users is given a high-data rate bearer this can result
in loss of coverage to users indoors
INDOOR COVERAGE ANALYSIS
Consider different RAB / coverage scenarios
Carefully estimate the effect of cell loading to
the coverage
Use repeaters if possible
Assess the need for indoor sites
Carry out real-life verification of the planning
- 84 -

Pilot pollution

Pilot pollution is faced on a certain area when there is no clearly

dominant CPICHs over the others.
The pilot pollution creates an abnormally high level of
interference, which is likely to result in the performance
problems
Increased interference level
Poor service quality, decreased throughput or increased
delay
Decreased service access
Frequent changes in Active Set and potential risk for
unnecessary handovers.
Higher non-controllable load

Pilot pollution

The yellow dots represent points where 4-5 CPICHs were

received within 6dB window
As Active Set size is typically 3, in this situation the rest of the
Pilots produce unnecessary interference

Pilot pollution

Pilot pollution can be (at least partly) avoided by planning the

CPICH powers and SHO parameters so that throughout the
network there is only 2-3 CPICHs available for the UEs, strong
enough to be included in the Active Set.
All CPICH outside Active Set should be clearly weaker
Antenna design, height and tilt are selected carefully
Balanced UL & DL
SCH/DCH power adjustments

- 85 -

Neighbour cell relations

The Monitored Set is also called as a Neighbour List. This list
can be defined in network planning and it can be later changed
in network optimization.
The list of neighbours play an important role since WCDMA is
interference limited. Insufficient planning of neighbour relations
will lead to unnecessary high interference
E.g. if suitable SHO candidate is not in the monitore set
and thus it is not selected to active set then its turning to
a pilot poIIuter
On the other hand, unnecessary neighbours increase
signalling and effects the SHO selection negatively
Accurate neighbour relations planning is much more important
than in GSM
In GSM it is possible to hide cell planning mistakes by
frequency planning, in CDMA the such inaccuracies will effect
the system capacity
The effort saved in frequency planning is spent in more detailed
cell planning

Neighbour cell relations

The parameters to control the neighbour relations and the
algorithms how system evaluates neighbours for cell lists,
depend on vendor
minimum CPICH RSCP or Ec/lo
Ec/lo margin
maximum number of neighbours
A neighboring set (or monitored set) is defined for each cell
Utilise planning tools automatised functions and check
with drive tests
Optimise according to CPICI-l coverage and SHO
parameters
UE monitors the neighboring set that may contain
Intra-frequency monitored list: Cells on the same WCDMA
carrier (Soft HO)
Inter-frequency neighbor list: Cells on another WCDMA
carrier (hard HO)
Inter-system neighbor list: For each neighboring PLMN
Missing neighbour can be detected during drive tests
If the best cell shown in the 3G scanner does not enter
the active set missing neighbour
- 86 -

Incilude the missing cell to neighbour list if its wanted to

active set or change cell plan if FIO

SHO optimisation

Soft/Softer HO planning and correct operation is one of the

most important means of optimizing WCDMA networks
The importance is high because of the high biterate (pathloss
sensitive) and RT (delay sensitive)
RABs
SHO is measured in terms of
probability, the percentage of all
connections that are in SHO state
The probability is effected by
network
planning and parameter settings

SHO optimisation

SHOs have effect to the network performance

Advantages
Required to avoid near-far effects
Coverage increases when more distant users can
connect
Capacity can be increased if more users can be
connected
Alongside with PC, SHO is the main interference
migitation means in WCDMA
Inconvenient
Requires more connections,
thus eats DL
transmission power and
decreases capacity
Introduces more interference
to DL
Increases the traffic in lub
40%
SHO probability 1.4 times
the traffic!

- 87 -

SHO optimisation

Probability for soft HO should be set to 30-50% and for softer

HO to 5-15%, depending on the area
Too high SHO% results in excess overlapping between
cells > other-cell interference increases > capacity
decreases
Too high SHO% also leads to poorly utilised network
capacity (unnecessary links)
With too low SHO% the full potential of network is not
utilised and transmission powers cannot be minimized >
trouble with interference
SHO performance is planned with a planning tool and optimised
by measurements in live network.
In early stage SHO% can be planned high, since the traffic
density is smaller. With increasing traffic coverage decreases
and SHO areas become smaller.
SHO% can be tuned with related parameters and dominance
areas
SHO most important in urban areas due to serious shadowing

Summary KPI
Indicator
Coverage
Interference
Cell overlap
Qualitative

KPI
KPI target example
Measured RSCP > -88 dBm over 97% of area
(value should be adapted based
on required margins)
Measured Ec/No > -9 dB over 95% of area
Cell overlay
< 3 cells over 95% of area
Cell Overshoot
No cell detected above -111
dBm (CPICH RSCP)
Integrity of cell
No cell fragmentation detected
coverage
Best server plot Clean boundary without unnecessary change of best server

- 88 -

Quality of Service

- 89 -

Quality of Service definitions (1)

QoS (ITU-T): << The collective effect of service performance which

determines the degree of satisfaction of a user of the service>>.
Network Performance, NP (ITU-T): << The ability of a network
portion to provide the functions related to communication between
users>>.

Quality of Service definitions (2)

User domain: throughput, accuracy, dependability (reliability,

availability),
Provider domain: delay, loss, utilisation,
User QoS
Requirements

QoS offered by
Provider

QoS experienced
By Users

QoS achieved by
User

Quality of Servicedefinitions (3)

QoS and NP, Performance network (ITU Rec.

E800)

- 90 -

Quality of Service and user

satisfaction
Commercial offer

Competition

Trends

User expectations in terms of QoS

Users satisfaction
Technical QoS

Network
performance

Non-technical QoS

Terminal
performance

Sales points

Radio Access Bearer QoS

- 91 -

Customer
care

Radio Access Bearer

Main task of the UTRAN is to create and maintain RAB for

communication between UE and CN.
RAB is build up in order to give for CN elements an illusion
about fixed communication path to UE.
The network builds up the end-to-end QoS connection from
small pieces, which compose a complete chain without
bottlenecks
These pieces are called Bearers
When the connection is set up, the network elements negotiate
the QoS requirements of the bearers set up between them
The result is a compromise, in which the QoS requirements and
networks capacity is taken into account.

UMTS QoS Classes

Traffic Class

Example application

Conversation class

Speech and video calls

Streaming class

Real-time streaming video

Interactive class

Web surfing

Background class

File downloading, e-mails

UMTS QoS Classes

Traffic Class

Properties

Conversation class

Minimum fixed delay, no buffering,

symmetric traffic, guaranteed bit rate
Minimum variable delay, buffering
allowed, asymmetric, guaranteed bit
rate
Moderate variable delay, buffering
allowed, asymmetric traffic, no
guaranteed bit rate
Big variable delay, buffering allowed,
asymmetric traffic, no guaranteed bit
rate

Streaming class
Interactive class
Background class

- 92 -

UMTS QoS Parameters

Parameter

Explanation

Maximum bit rate

Defines the maximum bit rate when

delivering information between end
points of UMTS bearer (<2Mbps)
Defines the bit rate that the UMTS bearer
must carry between its end points

Guaranteed bit rate

Allowed transfer delay Set the limits for delay (>80ms)

QoS negotiable

QoS of some services are not negotiable

(speech), packet data services admit
various QoS classes

Some values of QoS UMTS

parameters classes
Traffic class

Conversation Streaming Interactive

Maximum
throughput (kb/s)
Scheduling
Max. SDU size
(octers)
Corrupted SDU
delivery
Residual BER
5* 10-2, 10-2,
5* 10-3, 10-4,
10-6
SDU error rate
10-2, 7*10-3,
10-3
10-4, 10-5
Transfer delay
100 maximum
(ms)
value

Background

<2048
Yes/No
<_ 1500 or 1502
Yes/No
5* 10-2, 10-2, 4* 10-3, 10- 4* 10-3, 105,
5,
5* 10-3, 10-3,
10-4, 10-5, 10-6 6* 10-8
6* 10-8
10-1, 10-2,
10-3, 10-4, 10-3, 10-4,
7* 10-3, 10-3,
10-6
10-6
10-4, 10-5
250 maximum
value

- 93 -

QoS Negotiation

UTRA
(NB, RNC)

UE

CN

E2E service request

Maximum bit rate
Guaranteed bit rate
Transfer delay QoS
negotiable (y/n)

UMTS bearer service: Request for UMTS QoS Class

Maximum bit rate
Guaranteed bit rate
Transfer delay QoS
negotiable (y/n)
RAB assignment request
RRM: Admission control

Radio bearer and radio link

establishment

QoS negotiation
RAB assignment response

UMTS Bearer service with negotiated QoS

QoS in UMTS
In early UMTS Release 99 all conversational and streaming
class traffic were offered over the CS bearer
Voice
RT multimedia (e.g. videotelephony)
In early Release 99 only
Interactive and background class
traffic utilisises the PS bearer
Release 4 capable networks
introduce some streaming class
traffic on PS bearer as well
Release 5 brings along a full
portofolio of PS bearers also
utilised for conversation traffic

- 94 -

QoS in UMTS

The QoS over the air interface is implemented by matching

each radio bearer with a transport channel whose format set
defines the QoS parameters
The mapping is performed during the establishment of the RAB
RNC performs the mapping of RAB characteristics to actual
resource requirements (vendor dependent)
Example of mapping for web service, which belongs to the
interactive class

Parameters

Interactive Class

Radio Resource mapping

Maximum bit rate

128 kbps

SF=16

Maximum SDU size

1500

Map to Transport formats

Residual BER

10 -6

1/3 turbo encoder

Transfers Delay

NA

Interleaver=40 or 80 msec

Guaranteed bit rate

64 kbps

SF=16

Delivery order

yes

Use Acknowledged RLC

SDU Error Ratio

1%

Delivery of errorneous

NO

Set appropriate threshold

for
Use Acknowledged RLC

QoS in UMTS

Operators can define the wanted QoS profile (in HLR) per
subscriber
Users can be categorised (QoS differentiation) for various
tariffing schemes
Traffic handling priorities can be set (THP)

Business
Remote office Basic free time
Traffic class
All four allowed All four allowed Only
converational
(voice calls) and
background
Max bit rate
400 kbps
800 kbps
64 kbps
Guaranteed bit 384 kbps
64 kbps
12 kbps
rate
Allowed THPs THP 1 (e.g. for THP 2 (e.g. for THP 3
e-mail
file tranfer)
download)

- 95 -

QoS in UMTS

- 96 -

Measurement and
statistics collection

- 97 -

Measurement tools typology

Field
Measurements

Generic
Measurement
tools

OMC
counters
Specific
System
Measurements

Passive
capture tools
Calls
generators

A. Field measurements
Drive test equipment
measures
and
softwares

GPS

Controler

Energy
Processing

Mobile QoS test

equipment

Man to machine interface

Poor Coverage example

- 98 -

External antennas

Poor Cell Dominance example

Pilot Pollution example

- 99 -

Example of neighbor missing (Ec/Io)

Corner effect (Ec/Io)

- 100 -

QVOICE

QVS
PSTN /
ISDN
Cellular
Network

QVP-Server

Data collection
Post processing

QVP-Client

3 parts: QVM (QV Mobile), QVS (QV Stationary) et QVP (QV Post
processing).

B. System measurements
OMC measurements
Specific
Alcatel: RNO
Siemens: SPOTS
Ericsson: TEMS
Analyser

Generic
APIC from Metrica
MyCom from MYCom
AirCom
NetAct SQM: Nokia
OVPI: HP (for IP equipments)

- 101 -

KPI processing tools

Commercial tools:

BiVision
ADC/Metrica,
NetAct (Nokia, for 3G)
UTRAN Network and service

Analyzer (Tektronix)

Actix

Analysis based on OMC-R counters

Analysis tools using these counters (generally they are specific).

Example: RNO or NPA of Alcatel, SPOTS from Siemens, etc.

- 102 -

Passive tools examples

HP: Ovis (data services tests, producers KPIs).

RamCom: Network Consultant (A, Gb, Gi, Gn, Iub, Iur, Gi and
Gn interfaces)
Trafica (NetAct from Nokia)
Ipanema: Ipanema (2,5 G and 3G data traffic).
Cigale (Astellia): 2 and 3G traffic.

GIS display

- 103 -

K PI

- 104 -

Optimization process
Performance
measurements
Update of
parameters, site
configuration

Key Performance
Indicators (KPI)

Network
tuning

Reasons that lead to otimisation:

Improve the performance
Business reasons (cost-effective)
Troubleshooting

Performance
analysis

Network statistics

Network statistics are collected from different network elements

with counters
Different types of counters are used
KPIs are needed to provide information of the network
performance
Raw counter data too detailed to be used in monitoring and
optimisation (Some counters can be used as KPIs)

KPI definition

KPIs are composed from several counters

KPI categories
Accessibility
Retainability
Integrity
Documentation of KPIs is important
Same KPI can be defined from different counters or
formula can be incorrect
Measurement period must be reasonable
Too much averaging if too long
Not enough statistical information if too short
- 105 -

KPI Example

Optimisation based on KIPs:

Optimisation is performed
for each category
Find the worst performing
cells
Find the reasons behind
the poor performance
Make the changes in the
network
Monitor the performance
after the changes

- 106 -

Accessibility

- 107 -

Accessibility : call set-up

MS Originating Call Setup
Random Access
RRC Connection Setup
Service Request
Authentication
Security

RAB Assignment

Accessibility workflow

Alarms
Cell Availability
Counters

Performance
Analysis
Idle mode
RRC Connection
Random Access
NAS
RAB Assignment

Recommendation
&
Implementation

Verification of
changes

Other Modules

Performance
Measurements

Squal, Srxlev, qQualmin,

qRxLevMin,
maxTxPowerUl, t3212,
t3312, aichPower,
powerOffsetP0,
preambleRetransMax,
constantValueCprach

pmTotNoRrcConnectCsSucc
pmTotNoRrcConnectPsSucc
pmNoRabEstablishAttempt<RAB>
pmNoRabEstablishSuccess<RAB>
pmNoPageDiscardCmpLoadC
pmNoPagingAttemptUtranRejected

Worst performing cell for CS and PS

100

100

pmTotNoRrc ConnectReq CsSuccess

pmTotNoRrc ConnectReq Cs

pmTotNoRrc ConnectReq PsSuccess

pmTotNoRrc ConnectReq Ps

pmTotNoRab EstablishS uccess < RAB >

pmmTotNoRa bEstablish Attempt < RAB >

pmTotNoRab EstablishS uccess < RAB >

pmmTotNoRa bEstablish Attempt < RAB >

- 108 -

Service success set up rate (CS)

Speech

100x

pmTotNoRrcConnectReqCsSucc
x
pmTotNoRrcConnectReqCs

pmTotNoRabEstablishSuccessSpeech
pmmTotNoRabEstablishAttemptSpeech

Circuit-Switched 64
100x

pmTotNoRrcConnectReqCsSucc
x
pmTotNoRrcConnectReqCs

pmTotNoRabEstablishSuccessCS64
pmmTotNoRabEstablishAttemptCS64

Circuit-Switched 57
100x

pmTotNoRrcConnectReqCsSucc
x
pmTotNoRrcConnectReqCs

pmTotNoRabEstablishSuccessCS57
pmmTotNoRabEstablishAttemptCS57

Service success set up rate (PS)

Packet-Switched Data Streaming

100 x (Y) x

pmTotNoRabEstablishSuccessPacketStream + pmRabEstablishSuccessPacketStream128
pmTotNoRabEstablishAttemptPacketStream + pmRabEstablishAttemptPacketStream128

Where Y =

pmTotNoRrcConnectReqPsSuccess
PmTotNoRrcConnectReqPs

Packet-Switched Data
Interactive

pmTotNoRabEstablishSuccessInteractive
100 x (Y) x pmTotNoRabEstablishAttemptPacketInteractive + HS1_HardHO_Flow

Where
Yx

pmTotNoRrcConnectReqPsSuccess
pmTotNoRrcConnectReqPs

HS1_HardHO_Flow=
pmNoOutgoingHsHardHoAttempt pmNoHsHardHoReturnOidSource
-pmNoIncomingHsHardHoAttempt - pmNoHsHardHoReturnOldChTarget

- 109 -

Idle mode paging

Successful First and Repeated Page attempts of total

number of first attempts, Paging success rate in aMSC
100 x

NPAAG1RESUCC + NPAG2RESUCC
NPAG1GLTOT + NPAG1LOTOT

Paging intensity per cell in a RNC (if RNC, LA and RA

consist of exact same cells):
pmCnlnitPagingToldleUeLa + pmCninitPagingToldieUeRa + pmCnlnitPagingToldleUe
Measurement period x total number of cells in that RNC

Random access: preamble

detection

Number/percentage of false detections, which is the case that

preamble is detected but there is no enough energy in message
part, due to noise on the random access channel for a carrier (it
could be due to loss of AICH, wrong recognition of preamble or
loss of RACH message part after the UE sends message out):

pmNoPreambleFalseDetection or
pmNoPreambleFalseDetection x100%
pmPositiveMessages

Random access: AICH detection

Percentage of getting AICH but no RRC connection setup,

excluding cell (re)selection:

No of AICH_ACK-No of RRC connection setup-No of cell (re)selection during RRC establishment

No of AICH_ACK

- 110 -

x100%

Admission control: DL transmission

carrier power
DL transmission carrier power

Average DL TX power for a cell-carrier:

102

pmTransmittedCarrierPoweri x

i
2

=0
102

pmTransmittedCarrierPoweri

=0

Admission control: UL RSSI

Average UL RSSI for a cell-carrier:
62

[pmAverageRssii x (0.5xi 110.5)]

=0
62

pmAverageRssii
=0

Admission control: Air Interface

Speech Equivalent (ASE)
Average UL ASE for a cell:

Average DL ASE for a cell:

pmSumOfSampleAseUI
pmNoOfSampleAseUI

pmSumOfSampleAseDI

- 111 -

pmNoOfSampleAseDI

Admission control: code allocation

Code allocation failure for SFn, where n is the spreading factor for
a cell could be found in the following formula (as an example the
SF 128 was used):

pmNoDIChCodeAllocFailureSF128
pmNoDIChCodeAllocAttemptSF128

x100%

Admission control: compressed

mode

How many users are in compressed mode? Well the average

number of users in compressed mode for a cell:

pmSumCompMode
pmSampesCompMode

Admission control: load sharing

Ratio between RRc connection returning and redirection due to

load sharing for a cell:

pmNoOfReturingRrcConn
pmNoLoadSharingRrcConn

The failures can be observed by the successful rate of

directed retry to GSM for a cell:

pmNoDirRetrySuccess
pmNoDirectionRetryAtt

- 112 -

x100%

Retainability

- 113 -

Service retainability workflow

Performance
Analysis

Recommendation
&
Implementation

pmSystemRabRelease<RAB>
pmNormalRabRelease<RAB>
pmNoSysRelSpeechULSynch
pmNoOfTermSpeechCong
pmNoSysRelSpeechSoHo

Verification of
changes

Other Modules

Performance
Measurements

ReleaseConnOffset
maxTxPowerUl,SirMax,
MinPwrRl, treselection,
timetotrigger1,
reportingrange1

UL out of Synch
Congestion control,
SHO functions
IFHO functions
IRAT Handovers

Dropped call rate CS

Speech

100x

pmNoSystemRab ReleaseSpeech
(pmNoNormalrAB ReleaseSpeech + pmNoSystemRab ReleaseSpeech)

Circuit-switched 64
100x

pmNoSystemRabReleaseCs64
(pmNoNormalRab ReleaseCs64 + pmNoSystemRab ReleaseCs64)

Circuit-switched
Streaming
100x

pmNoSystemRabReleaseCsStream
(pmNoNormalrRab ReleaseCsStream + pmNoSystemRab ReleaseCsStream)

Dropped call rate PS

Packet Switched data Streaming
100x

pmNoSystemRabReleasePacketStream + pmNoSystemRabReleasePacketStream128
(pmNoNormalRabReleasePacketStream + pmNoSystemRabReleasePacketStream + pmNosystemRabReleasePacketStream128)

Packet Switched data Interactive

100x

pmNoSystemRabReleasePacket
(pmNoNormalRabReleasePacket + pmNoSystemRabReleasePacket)

- 114 -

Minutes per drop CS

Speech

Sp_U_User

100x

pmNoSystemRabReleaseSpeech

x number of minutes

Circuit-switched 64
Cs64_U_User

100x

pmNoSystemRabReleaseCs64

Circuit-switched
Streaming
100x

x number of minutes

Cs57_U_User

x number of minutes
pmNoSystemRabReleaseCsStream

Minutes per drop PS

Packet Switched data
Streaming

100

Pstr_P8_U_User
pmNoSyatemRab ReleasePacketStream + pmNoSystemRab ReleasePacketStream128

x No of minutes

Packet Switched data

Interactive
100

Plntdch_U_User+PlntHs_U_User+PlntFach_U_User
pmNoSystemRab ReleasePacket

x No of minutes

Packet Switched
data Interactive HS
100

PlntHs_U_User
pmNoSystemRab ReleaseHs

x No of minutes

Handover failure rate

The following formula shows the failure rate for RL

addition/replacement to active set
100x

pmNoTimesCellFailAddToActSet
(pmNoTimesCellFailAddToAct + pmNoTimesRlAddToActSet

- 115 -

Handover failure rate: HS cell

change

The following metric measures the success rate for HS Cell

Change in target cell

100x

pmHsCcSuccess
pmHsCcAttempt

Handover failure rate: out of

synchronization

Shows fraction of drop due to uplink Out of Sync reason.

100x

(pmNoSysRelSpeechULSynch)
(pmNoNormalRabReleaseSpeech + pmNoSystemRabReleaseSpeech)

Handover failure rate: missing

neighbor
100x

pmNoSysRelSpeechSoHo

(pmNoSystemRabReleaseSpeech + pmNoNormalRabReleaseSpeech)

Shows fraction of speech drop due to HO action when a valid

or non-valid cell cannot be added to active set. This includes
also drop due to missing neighbour.
100x

pmNoSysRelSpeechNeighbr
(pmNoSystemRabReleaseSpeech + pmNoNormalRabReleaseSpeech)

Shows fraction of speech drop due to missing neighbour

reason when a non-valid cell cannot ne added to active set.

- 116 -

Inter-frequency handover failure

rate (CS)

Drop due to IHO failure for speech: Outgoing IFHO failure when
UE failed to return to present active set.

100x

pmFailNonBlindInterFreqHoFailRevertCsSpeech12
pmAttNonBlindInterFreqHoCsSpeech12

Inter-frequency handover failure

rate (PS)
Drop due to IFHO failure for PS less or equal to 64 kbps:
Outgoing IFHO failure when UE failed to return to present
active set.
100x

pmFailNonBlindInterFreqHoFailRevertPsInteractiveLess64
pmAttNonBlindInterFreqHoPsInteractiveLess64

Drop due to IFHO failure for PS greater than 64 kbps: Outgoing

IFHO failure when UE failed to return to present active set.
100x

pmFailNonBlindInterFreqHoFailRevertPsInteractiveGreater64
pmAttNonBlindInterFreqHoPsInteractiveGreater64

Drop due to IFHO failure for PS streaming and others:

Outgoing IFHO failure when UE failed to return to present
active set.
100x

pmFailNonBlindInterFreqHoFailRevertStreamingOther
pmAttNonBlindInterFreqHoStreamingOther

- 117 -

IRAT handover

The following metric measures hard handover success rate

between UtranCell and target GSM cell for speech calls. The
formula is considering the GsmRelation.
100x

pmNoSuccessOutIratHoSpeech
pmNoAttOutIratHoSpeech

The following metric measures hard handover success rate

between UtranCell and target GSM cell for streaming calls. The
formula is considering the GsmRelation.
100x

pmNoSuccessOutIratHoCs57
pmNoAttOutIratHoCs57

IRAT handover

The following metric measures hard handover success rate

between UtranCell and target GSM cell for Multi-RAB calls. The
formula is considering the GsmRelation.
100x

pmNoSuccessOutIratHoMulti
pmNoAttOutIratHoMulti

The following metric measures cell change failure rate between

UtranCell and target GSM cell for PS calls when the UE
successfully returns to UtranCell. The formula is considering the
GsmRelation.
100x

pmNoOutIratCcReturnOldCh
pmNoOutIratCcAtt

Congestion

Shows fraction of speech drop due to cogestion action

100x

(pmNoOfTermSpeechCong)
(pmNoNormalRabReleaseSpeech + pmNoSystemRabReleaseSpeech)

Shows fraction of video call drop due to cogestion action

100x

(pmNoOfTermSpeechCong)
(pmNoNormalRabReleaseCs64 + pmNoSystemRabReleaseCs64)

- 118 -

Integrity

- 119 -

Service integrity workflow

Performance
Measurements

Performance
Analysis

BLER counters
and Down
Switching counters

Verification of
changes

Recommendation
&
Implementation

BLER, power,
SIR parameters

Test the settings

Check statistics
If not OK, roll back

Throughput

pmFaultyTransportBlocksBcUl
pmTransportBlocksBcUl
pmNoOfSwDownNgCong
PmNoOfSwDownNgAdm
PmDl Traffic volume counters

BLER

The method for finding worst performing cells is based on top to

down analysis. Initial worst 10-15 performing cells can be identified
based on the Uplink Block Error rate before combining.
100x

pmFaultyTranspoertBlocksBcUL
pmTransportBlocksBcUI

Throughput

Average throughput per cell and RAB in the DL, excluding

HSDPA:
Throughput =

pmDlTrafficVolume<RAB>
pmSum<RAB>RabEstablish

pmSamples<RAB>RabEstablish

*ROPsec

RAB efficiency excluding HSDPA

The RAB efficiency can also be checked
RABEfficiency =
UeRc stands for different RABs
UeRc=2, Speech
UeRc=3, Video Call
UeRc=4, Packet Common Channel
UeRc=5, PS 64/64
UeRc=6, PS64/128
UeRc=7, PS 64/384
UeRc=10 multirab Speech+PS 0 or PS 64/64).

- 120 -

Actual Bitrate per RAB

Nominal Bitrate per UeRc=x

Payload counters
Radio
UL Payload counter
DL Payload counter
Connection
type
Speech
pmUITrafficVolumeCs12
pmUITrafficVolumeCs12
PS64/64
pmUITrafficVolumePs64
pmUITrafficVolumePs64
PS64/128
pmUITrafficVolumePs128
pmUITrafficVolumePs128
PS64/384
pmUITrafficVolumePs384
pmUITrafficVolumePs384
CS 57.6
pmUITrafficVolumeCs57
pmUITrafficVolumeCs57
(streaming)
CS 64 (UDI)
pmUITrafficVolumeCs57
pmUITrafficVolumeCs57
Speech/PS pmUITrafficVolumeCs12Ps64 pmUITrafficVolumeCs12Ps64
64 multirab
PS
pmUITrafficVolumePsCommon pmUITrafficVolumePsCommon
Common

- 121 -

HSDPA-HSUPA

- 122 -

HSPA Key features-AMC

Cood CQI
Bad CQI

High Code
Effective Rate

Good coverage

Low Code Effective

Rate

Channel Quality Feedback

(CQI)
UE measures channel quality
(SNR or Ec/No) and reports to
Node B every 2ms or longer
time.
Node B chooses modulation
scheme, transport block size
and code effective rate based
on CQI

Bad coverage

AMC could improve radio bandwidth and fit for high speed radio transmission.

HSPA Key feature System

resource
Resource allocation

Reasonable resource allocation can improve throughput

performance

OVSF Code resource

Minimum Code available for HSPA but

not for R99, so this resource cant
allocated too much to avoid no code
for HSPA access channel.

DCH Code
HSPA Maximum
For R99 and HSPA access and traffic channel
Code

Power resource

Threshold for R99 load control,

which should not be allocated too
much to avoid no power for
HSPA user

- 123 -

HSPA Minimum
Code

HSPA Key feature-Scheduling

Transmission slot 2 ms
UE2
UE1

UE3

Data transmission slot

Mobility management

- 124 -

Sample message flow to begin

HSDPA operation
UE

Bode B

RNC

UTRAN decides to start HSDPA for the UE

Measurement Control message (Setup Event 1d)
2
Measurement Report message (Report Event 1d)
Radio link reconfiguration prepare
3
Radio link reconfiguration ready
Radio link reconfiguration commit
Radio Bearer Reconfiguration message
4

User plan data can flow on the HS-DSCH

Radio Bearer Reconfiguration Complete message

Sample message flow to stop

HSDPA operation
UE

Bode B

UTRAN decides to stop HSDPA but keep DCH for the UE due to:

Low Downlink data activity

High UE mobility

Radio link reconfiguration prepare

Radio link reconfiguration ready

Radio link reconfiguration commit
Radio Bearer Reconfiguration message
3

RNC

User plane data only flows on the DCH

Radio Bearer Reconfiguration message

- 125 -

Cell change triggering with event 1d

Ec/No

Cell 1

Cell 2

Hysteresis

Time-to-

Cell change

HS-DSCH on Cell 1

HS-DSCH on

Time

Differences about information

collection between R99 and HSPA

- 126 -

HSPA dimensioning optimization

HSPA Optimization target Improve

CQI
HSPA RF optimization target

R99 RF optimization target

CQI

RSCP & Ec/Io

Make sure that CQI is distributed as

appropriate proportion. Cell edge
throughput requirement could be
fulfilled in the door coverage area.

Make sure that cell gets target

coverage probability

CDI

9>CQI

15>CQI 9

CQI 15

User experience

Poor

Fair

Good

Equipment Ec/Io

-15dB

-15 dB - -9dB

- 127 -

-9dB

Performance Optimization
Procedure

The three kind of KPI of should be paid more attention

HSPA CALL SUCCESS RATIO
HSPA HANDOVER SUCCESS RATIO
HSPA THROUGHPUT PERFORMANCE

KPI Collection
DT/CQT/Statistics

Performance optimization

Problem Analyze

Modify the load balance policy

Carry out smart admission

Code congestion
Power overload
HSPA subscriber

algorithm such as DRD or

Downsize Access

number overload

Power and lub bandwidth

lub bandwidth

congestion means the

capacity should be expanded

congestion

Unsupported

The higher bit rate such as

configuration by UE

13.6K DCH channel can help

to improve access performance

Inter-freq Handover is the most

difficult for HSPA mobility
optimization

- 128 -

HSPA Throughput Optimization

The Power and Codes available for HS-PDSCH, the lub bandwidth
and RF environment of UE position will all impact throughput user
got.
Available Codes for HSPA
Available Power for HSPA

Available lub backhaul for HSPA

The Data Power to be transmitted
Node B

DATA
DATA
DATA

Check
point

CQI

The air
environment
condition

DATA

RNC

CQI

CQI

The data
should be
delivered

GSN
Process
ability

CQI
The web sever
performance.

SGSN/GGSN
App Sever

- 129 -

Firewall

- 130 -