07_WCDMA Radio Network Capacity Planning
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Transcript of 07_WCDMA Radio Network Capacity Planning
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www.huawei.com
Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA Radio
Network Capacity
Planning
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Page1Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.
Foreword
l WCDMA is a self-interference system
l WCDMA system capacity is closely related to coverage
l WCDMA network capacity has the soft capacity! feature
l The WCDMA network capacity restriction factors in the radio
network part include the following:
p Uplink interference
p Downlink power
p Downlink channel code resources (OVSF)
p Channel element (CE)
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Objectives
l Upon completion of this course, you will be able to:
p Grasp the parameters of 3G traffic model
p Understand the factors that restrict the WCDMA network
capacity
p Understand the methods and procedures of estimating multi-
service capacity
p Understand the key technologies for enhancing network
capacity
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Contents
1. Traffic Model
1.1 Overview of traffic model
1.2 CS traffic model
1.3 PS traffic model
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UMTS QoS Type
Data integrity should be maintained. Small delay
restriction, requiring correct transmission
Request-response mode, data integrity must be
maintained. High requirements on error tolerance,
low requirements on time delay tolerance
Typically unidirectional services, high
requirements on error tolerance, high
requirements on data rate
It is necessary to maintain the time relationship
between the information entities in the stream.
Small time delay tolerance, requiring data rate
symmetry
Background
download of
Background
Web page
browse,
network game
Interactive
N onr e al - t
i m e c a t e g or y
Streaming
multimediaStreaming
Voice service,
videophoneConversation
al
R e al - t i m e c a t e g or y
l For the session-type service, requirement on end-to-end delay is strict. For example, for
the voice service, the delay is required to be smaller than 150ms, and must not exceed
400ms, otherwise, it will be difficult to understand the voice. The session-type servicesare typically carried by the CS domain. For the session-type services, the system can
perform no queue processing for the calls. In this case, we can use the Erlang B formula
or the extended Erlang B formula to calculate.
l Compared with the session-type service, the stream-type service imposes low
requirement on the end-to-end delay. Generally, the stream-type service tolerates the
call waiting to a greater extent, and can provide the call queue mechanism. In this case,
we can use the Erlang C formula to calculate the blocking probability of this type of
users (defined as the probability of the call waiting for a specified time).
l Interaction-type service refers to the service through which the user requests data from
the server. The service is described with the terminal user "s request response pattern.
Therefore, round-trip delay is the most important index of this service type. The
interaction-type services are typically carried on the CS domain. The background-
service tolerates delay to the greatest extent, and can tolerate the delay of a magnitude
of an hour. Due to such great delay tolerance, the system can save such requests in the
busy hour, and respond when the channel becomes idle; meanwhile, for such services,
once a request with higher QoS comes in, the processing can be stopped at any time.
The system decides startup and termination at any time, the above formulas#Erlang B
formula and Erlang C formula are not applicable. Generally, according to the difference
between the maximum number of channels and the busy-hour average occupied
channels, we can calculate the traffic of the background-type service. The users of
traffic-type services also tolerate the call waiting to some extent. The system provides aqueue mechanism, and uses the Erlang C formula to calculate the blocking rate.
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Traffic Model
System Configuration
User Behaviour
Service Pattern
Traffic Model
Results
l By determining the service pattern and the user behaviour parameters, we
determine the traffic models of various services in the network. By calculating
the hybrid services of multiple traffic models, we determine the network system
configuration.
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The Contents of Traffic Model
l Service pattern refers to the service features
l User behaviour refers to the conduct of people in using the
service
l Service pattern is a means of researching the capacity features of each service
type and the QoS expected by the users who are using the service from
perspective of data transmission. In the actual application, service pattern is
closely related to, and sometimes is no strictly different from, the traffic
measurement model.
l In the data application, the user behaviour research mainly forecasts the service
types available from the 3G, the number of users of each service type,
frequency of using the service, and the distribution of users in different regions
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Typical Service Features
Descriptionl Typical service features include the following feature
parameters:
p User type (indoor ,outdoor, vehicle)
p User "s average moving speed
p Service Type
p Uplink and downlink service rates
p Spreading factor
p Time delay requirements of the service
l For each service, since the channel structure and demodulation method are
different, the required uplink rate is different from the required downlink rate
even for the same service type and the same data rate. For a typical service, we
first need to identify whether it is uplink or downlink rate. A typical service can
be described by the following parameters:
p User type (indoor users, users inside a vehicle, outdoor users)
p User "s average moving speed (km/h)
p Voice, real-time data, non real time data
p Uplink and downlink service rates (kbps)
p Spread factor (SF)
p Signal delay requirement of the service (ms).
l The above parameters ultimately determine the QoS requirements of the
service.
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Contents
1. Traffic Model
1.1 Overview of traffic model
1.2 CS traffic model
1.3 PS traffic model
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CS Traffic Model
l Voice service is a typical CS services. Voice data arrival conforms
to the Poisson distribution. Its time interval conforms to the
exponent distribution
l Key parameters of the model
p Penetration rate
p BHCA: busy-hour call attempts
p Mean call duration (s)
p
Activity factor p Mean rate of service (kbps)
l Penetration rate: The percentage of the users that activates this service to all
the users registered in the network.
l Activity Factor: The weight of the time of service full-rate transmission among
the duration of a single session.
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CS Traffic Model Parameters
l Mean busy-hour traffic (Erlang) per user = BHCA × mean call
duration /3600
l Mean busy hour traffic volume per user (kbit) = BHCA × mean call
duration × activity factor × mean rate
l Mean busy hour throughput per user (bps) = mean busy hour
traffic volume per user × 1000/3600
l (Erl) For CS service, mean busy-hour traffic (Erlang) per user = BHCA * mean
call duration /3600 (Erl)
l (kbps) Mean busy-hour throughput per user = BHCA * mean call duration *
activity factor * mean rate of service*1000/3600 (kbps)
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Contents
1. Traffic Model
1.1 Overview of traffic model
1.2 CS traffic model
1.3 PS traffic model
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PS Traffic Model
Data Burst Data Burst Data Burst
Packet Call
Session
Packet Call Packet Call
Downloading Downloading
Active Dormant Dormant Active
l The most frequently used model is the packet service session process model
described in ETSI UMTS30.03.
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PS Traffic Model Parameters
Traffic Model
Packet Call Num/Session
Packet Num/Packet Call
Packet Size (bytes)
BLER
Typical Bear Rate (kbps)
Reading Time (sec)
l The service pattern-related parameters in the traffic model include: these
parameters commonly determine the pattern of one session.
l We identify the service types through the different values of the parameters.
p Packet Call Num/Session: Takes on the geometric random distribution
p Reading Time (sec): Takes on the geographic random distribution
p Packet Num/Packet Call: Takes on the geographic random distribution
p Packet size: Takes on the Pareto random distribution
l When using the parameters, the average values will apply.
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PS Traffic Model Parameters
l Typical Rate (kbps)
l BLER ( Block error ratio ):
p The retransmission caused by error blocks should be
considered
p Assume that PS service data volume is N, block error rate is
BLER, the total data volume to be transmitted is:
l During the planning, according to the actual situation, we select the typical value
of the bear rate. It will affect the active factor, but will not affect the correctness
of the planning result.
l Block error rate (BLER) belongs to QoS. The service control mechanism will
retransmit the erroneous blocks. This will increase the traffic to be transmitted.
l Actually, retransmission rate is equal to 1/(1-BLER)
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PS User Behaviour Parameters
User Behaviour
User Distribution
(High, Medium, Low end)
BHSA
Penetration Rate
l The country, region, life custom and economic level will affect the service
distribution. In the planning, we divide the users into high-end users, mid-end
users and low-end users, and believe that the BHSA and penetration rate are
different between different types of user groups. Currently, we can only use the
existing analysis to make prediction. In the future, the progress of the
construction of the WCDMA pilot system will provide us with reference.
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PS User Behaviour Parameters
l Penetration Rate
p The percentage of the users that activate this service to all the
users registered in the network
l BHSA
p The times of single-user busy hour sessions of this service
l User Distribution (High, Medium, Low end)
p The users are divided into high-end, mid-end and low-end
users.
l Penetration Rate: The percentage of the users that activate this service to all
the users registered in the network. It varies between different service types,
user types, and operators. More importantly, it is related to the penetration rate
and time. With the elapse of time, the penetration rate will increase gradually.
l BHSA: Times of the single-user busy hour sessions of the service. It varies
between service types and user types.
l User Distribution (High, Medium, Low end): The users are divided into high-
end, mid-end and low-end users according to the ARPU. Different operators
and different application situations will have different user distributions.
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PS Traffic Model Parameters
l Session Traffic Volume ( byte ) : mean traffic volume of one
session in one PS service
l Data transmission time ( second ) : mean duration of data
transmission in one session at one PS service
l
Holding Time ( second ) : mean duration of one session inone PS service
l Based on the traffic model figure, it is easy to calculate the session traffic
volume. The transmission time should include the retransmitting times.
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PS Traffic Model Parameters
l Active Factor : The weight of the time of service full-rate
transmission among the duration of a single session
l Throughput per user at busy hour :
l PS throughput equivalent Erlang Formula :
l Based on Busy hour throughput per user and the Active factor, we can calculate
the Erlang which similar with CS service.
l Erlang = Busy hour throughput per user /!typical rate * Active factor * 3600"
l Busy hour throughput per user, Active factor, Session traffic volume and Data
transmission time are based on PS traffic model basic parameters. In another
word, for one whole PS traffic model, the parameters should be determined are :
Penetration Rate, BHSA, typical rate, BLER, Packetcallnum/session,
Packetnum/Packetcall, Packet size and reading time/session.
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Basic Principles
l In the WCDMA system, all the cells use the same frequency,
which is conducive to improving the WCDMA system
capacity. However, for reason of co-frequency multiplexing,
the system incurs interference between users. This multi-
access interference restricts the capacity in turn.
l The radio system capacity is decided by uplink and
downlink. When planning the capacity, we must analyze
from both uplink and downlink perspectives.
l Interference is the main factor that decides the system performance of the
cellular system. The interference in a cellular system consists of two parts: co-
frequency and adjacent frequency interference. All users in the WCDMA system
use the same band. All the users are different by modulating the respective
signal to the code sequences that are mutually orthogonal. Therefore, the
receiving signal is the sum of all user signals and the channel noise.
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Contents
2. Interference Analysis
2.1 Uplink Interference Analysis
2.2 Downlink Interference Analysis
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Uplink Interference Analysis
l Uplink interference analysis is based on the following
formula:
N other ownTOT P I I I ++=
l Where:
p : Total interference received by NodeB
p : Interference from the users of this cell
p : Interference from the users of adjacent cells
p : Noise floor of the receiver
own I
other I
N P
TOT I
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Uplink Interference Analysis
l Receiver noise floor: P N
p For Huawei NodeB, the typical value is -106.4dBm/3.84MHZ
NF W T K P N +××= )log(10
l K : Boltzmann constant, 1.38 10 -23J/K
l T : Temperature in Kelvin, normal temperature: 290 K
l W : Signal bandwidth, WCDMA signal bandwidth 3.84MHz
l N th
= 10log(K*T*W)=-108dBm/3.84MHz
l NF : For Huawei NodeB, typical value is 1.6dB.
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Uplink Interference Analysis
l : Interference from users of this cell
p Interference that every user must overcome is :
p is the receiving power of the user j , is UL activity factor
p Under the ideal power control :
p Hence:
p The interference from users of this cell is the sum of power of
all the users arriving at the receiver:
own I
jtotal P I −
jρ
j P
( )
j j jTOT
j
No Eb
R
W
P I
P j Avg
ρ
110 10
/ _
⋅⋅−
=
( ) j j
No Eb
TOT j
R
W
I P
j Avg ρ
1
10
11
10
/ _ ⋅⋅+
=
∑= N
jown P I 1
l Activity Factor: The weight of the time of service full-rate transmission among
the duration of a single session. Which is defined by the following formula:
e HoldingTim
issionTime DataTransmor ActiveFact =
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Uplink Interference Analysis
l :Interference from users of adjacent cell
p The interference from users of adjacent cell is difficult to
analyze theoretically, because it is related to user distribution,
cell layout, and antenna direction diagram.
p Adjacent cell interference factor
own
other
I
I f =
other I
l When the users are distributed evenly
p For omni cell, the typical value of adjacent cell interference factor is 0.55
p For the 3-sector directional cell, the typical value of adjacent cell
interference factor is 0.65
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Uplink Interference Analysis
( )
( )
N
N
j j
No Eb
TOT N other ownTOT P
R
W
I f P I I I
j Avg
+
⋅⋅+
+=++= ∑1
10
/
1
10
11
1
_ ρ
( ) j j
No Eb
j
R
W L
j Avg ρ
1
10
11
1
10
/ _ ⋅⋅+
=
( ) N
N
jTOT TOT P L f I I +⋅+⋅=
∑11
Define:
Then:
( ) ∑⋅+−
⋅= N
j
N TOT
L f
P I
1
11
1Obtain:
l Where:
p N is the number of users in the cell.
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Uplink Interference Analysis
l Suppose that:
p All the users are 12.2 kbps voice users, Eb/No Avg = 5dB
p Voice activity factor = 0.67
p Adjacent cell interference factor f =0.55
jρ
l Under the above assumption, the threshold capacity is approx 96 users.
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Uplink Interference Analysis
l According to the above mentioned relationship, the noise will rise:
UL
N
j N
TOT
L f P
I NoiseRise
η−=
+−
==
∑1
1
)1(1
1
1
l The NoiseRise is used in link budget to estimate the Interference Margin
l If uplink cell load is 50%, NoiseRise will be 3dB
l If uplink cell load is 60%, NoiseRise will be 4dB
l If uplink cell load is 75%, NoiseRise will be 6dB
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Uplink Interference Analysis
l Define the uplink load factor for one user:
l Define the uplink load factor for the cell:
( ) ( )( )
∑∑⋅⋅+
×+=×+= N
j j
EbvsNo
N
jUL
R
W f L f
j Avg
1
10
11
10
11
111
_ ρ
η
( ) ( )
( ) j j
EbvsNo
j j
R
W f L f
j Avg ρ
η1
10
11
111
10
_ ⋅⋅+
×+=×+=
l When the uplink load factor is 1, is infinite, and the corresponding capacity
is called threshold capacity!.
TOT I
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Uplink Interference Analysis Limitation
l The above mentioned theoretic analysis uses the following
simplifying explicitly or implicitly:
p No consideration of the influence of soft handover
p No consideration of the influence of AMRC and hybrid service
p Ideal power control assumption
p Assume that the users are distributed evenly, and the adjacent cell
interference is constant
l Considering the above factors, the system simulation is a more
accurate method:
p Static simulation: Monte_Carlo method
p Dynamic simulation
l No consideration of the influence of soft handover
p The users in the soft handover state generates the interference which is
slightly less than that generated by ordinary users.
l No consideration of the influence of AMRC and hybrid service
p AMRC reduces the voice service rate of some users, and makes them
generate less interference, and make the system support more users.
(But call quality of such users will be deteriorated)
p Different services have different data rates and demodulation thresholds.
So, we should use the previous methods for analysis, but it will
complicate the calculation process.p Since the time-variable feature of the mobile transmission environment,
the demodulation threshold even for the same service is time-variable.
l Ideal power control assumption
p The power control commands of the actual system have certain error
codes so that the power control process is not ideal, and reduces the
system capacity
l Assume that the users are distributed evenly, and the adjacent cell interference
is constant
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Contents
2. Interference Analysis
2.1 Uplink Interference Analysis
2.2 Downlink Interference Analysis
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Downlink Interference Analysis
l Downlink interference analysis is based on the following
formula:
N other ownTOT P I I I ++=
l Where:
p : Total interference received by UE
p : Interference from downlink signal of this cell
p : Interference from downlink signal of adjacent cells
p : Noise floor of the receiver
own I
other I
N P
TOT I
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Downlink Interference Analysis
l Receiver noise floor: P N
p For commercial UE, the typical value is -101dBm/3.84MHZ
NF W T K P N +××= )log(10
l K : Boltzmann constant, 1.38 10 -23J/K
l T : Temperature in Kelvin, normal temperature: 290 K
l W : Signal bandwidth, WCDMA signal bandwidth 3.84MHz
l N th
= 10log(K*T*W)=-108dBm/3.84MHz
l NF : For commercial UE, typical value is 7dB.
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Downlink Interference Analysis
l :Interference from downlink signal of this cell
p The downlink users are identified with the mutually orthogonal
OVSF codes. In the static propagation conditions without multi-
path, no mutual interference exists.
p In case of multi-path propagation, certain energy will be
detected by the RAKE receiver, and become interference
signals. We define the non-orthogonal factor to describe this
phenomenon:
own I
TX jown P I ×=α)(
α
l Compared to the uplink load equation, the most important new parameter is ,
which represents the non-orthogonality factor in the downlink. WCDMA employs
orthogonal codes in the downlink to separate users, and without any multi-path
propagation the orthogonality remains when the base station signal is received
by the mobile. However, if there is sufficient delay spread in the radio channel,
the mobile will see part of the base station signal as multiple access
interference. The orthogonality of 1 corresponds to perfectly orthogonal users.
Typically, the non-orthogonality is between 0.1 and 0.6 in multi-path channels.
l Where:
p P TX is the actual transmission power of NodeB
α
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Downlink Interference Analysis
l : Interference from the downlink signal of adjacent cell
p The transmitting signal of the adjacent cell NodeB will cause
interference to the users in the current cell. Since the
scrambling codes of users are different, such interference is
non-orthogonal
p Hence we obtain:
other I
TX jother P f I ×=)(
l Where:
p is Adjacent cell interference factor
p P TX is the actual transmission power of NodeB
f
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Downlink Interference Analysis
l Ec/Io for User j is:
10/)(10/
10/
10/
10)(10
10
)(10)(
N N
P CL
TX
j
P
CL
TX
CL
j
j P f
P
P f
P
Io
Ec+
+×+=
+×+
=αα
l Where:
p P j
is the transmission power of NodeB for User j
p CL is Downlink Coupling Loss, is equals to:
n PL_DL: Downlink path loss
n Lf_BS: cable loss of NodeB
n Ga_antenna: Gain of UE antenna and NodeB antenna
n Lb: Body loss
n SFM NSHO
: Slow fading margin without soft handover
n Lp: Penetration loss
l Therefore:
p is the useful power received by user j
p is the interference from own cell and adjacent
cell, and it includes I own and I other
p is the noise floor of UE
LpSFM LbantennaGa BS Lf DL PLCL NSHO +++−+= _ _ _
10/10
CL
j P
10/
max _
10
)(CL
Total DL P f ××+ ηα
10/10 N P
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Downlink Interference Analysis
l Under the ideal power control:
l Then we can get:
j j
j
No Eb
R
W
Io
Ec j
ρ
1)(10 10
)/(
××=
j
TX
P CL
TX j
No Eb
j RW
P f P
P
N j
/
)10
(1010/)(
10
)/( +
++×××
=
αρ
l Where:
p W is the chip rate, which is 3.84Mcps
p R j is the bit rate of service.
p is the activity factor. jρ
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Downlink Interference Analysis
l Define the downlink load factor for user j:
l Define the downlink load factor for the cell:
max P
P TX DL =η
j
TX
P CL
TX j
No Eb
j
j RW
P f
P
P
P
P
N j
/
)10
(1010/)(
max
10
)/(
max
+
++×××
==
αρ
η
l The downlink load factor are defined in the transmitter side (NodeB).
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Downlink Interference Analysis
l According to the above mentioned relationship, the noise will rise:
( )
N
DL Max
N
other own N
N
total
P
CL P f No
P
I I P
P
I NoiseRise
/ηα ××++=
++==
l The NoiseRise is used in link budget to estimate the Interference Margin
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Capacity Dimensioning FlowDimensioning Start
Assumed Subscribers
CS Peak Cell Load(MDE)
Yes
No
CS Average Cell Load PS Average Cell Load
=Target Cell Load?
Dimensioning End
Total Cell Load
Load per Connection of R99
HSPA Cell Load
Load Load Load , Load max Load HSUPAavg PS avg CS peak CS UL _ total cell ++= −−−−
CCH HSDPAavg PS avg CS peak CS DL _ total cell Load Load Load Load , Load max Load +++= −−−−
l For UL, the load per connection of R99 is calculated by the following formula:
l For DL, the load per connection of R99 is calculated by the following formula:
l Typical Value: ( for AMR 12.2k is 0.67, is 0.65, is 50%, is 75%,
load of CCH is 20%, Channel model is TU3, DL CL is 135dB, is 0.5, NodeB
max transmission power is 43dBm)
( ) ( )( )
j j
EbvsNo
j j
R
W f L f
j Avg ρ
η 1
10
11
111
10
_
⋅⋅+×+=×+=
j
TX
P CL
TX j
No Eb
ii
RW
P f
P
P
P
P
N j
/
)10
(1010/)(
max
10
)/(
max
+
++×××
==
αρ
η
19.59%21.35%PS384k
8.03%8.69%PS128k
4.11%4.77%PS64k
5.81%4.99%CS64k
1.05%1.19% AMR12.2k
DownlinkUplinkLoad per User
jρ f ULη ULη
α
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Capacity Dimensioning Differences
GSM
l Hard blocking
l Capacity --- hardware dependent
l Single service
l Single GoS requirement
l Capacity dimensioning ---ErlangB
WCDMA
l Soft blocking
l Capacity --- interference dependent
l Multi services (CS&PS)
l Respective quality requirements of
each service
l Capacity dimensioning ---
Multidimensional ErlangB
l The GSM capacity is decided by the number of carriers, it is hard capacity. But
WCDMA capacity is related to interference, coverage, channel condition, it is
soft capacity.
l The Erlang-B formula is only used for
p Circuit switched services
p Single service
l Multidimensional ErlangB (MDE) is suitable for:
p Multi service with different GoS
p Different service will share the same resource.
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Multidimensional ElangB Principle (1)
l Multidimensional ErlangB model is a Stochastic Knapsack Problem.
l Knapsack ! means a system with fixed capacity, various objects arrive at
the knapsack randomly and the states of multi-objects in the knapsack
are stochastic process.
l Then when various objects attempt to access in this system, how much is
the blocking probability of every object?
K classes of
services
Blockedcalls
Callsarrival
Callscompletion
Fixed capaciy
l Multidimensional ErlangB is a public algorithm. Now Huawei selects it.
Operators can use different algorithm to calculate the load.
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Multidimensional ElangB Principle (2)
l Case Study: Two dimensional ErlangB Model
p The size of service 2 is twice as that of service 1
p C is the fixed capacity
n2
Blocking States of Class 1
C
C-b1
n1
n2
Blocking States of Class 2
C
C-b2
n11 2 3 4 5 6
1
2
3
1 2 3 4 5 6
1
2
3
n2
States Space
C
n11 2 3 4 5 6
1
2
3
Ω
l b1:size of service 1, which means the resource required by service 1 .
l b2:size of service 2, which means the resource required by service 2 .
l b2=2*b1
l n1: number of service 1 connection
l n2: number of service 2 connection
l The left graph describes all the states (blue dots) that satisfies:
n1*b1+n2*b2<=C
l The red dots in the central graph describe the blocking states for service 1, that
means in these red states, service 1 cannot access the network.
l The red dots in the central graph describe the blocking states for service 1, that
means in these red states, service 1 cannot access the network.
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CS Capacity Dimensioning (1)
l CS services
p Real time
p GoS requirements
l Multidimensional ErlangB
p Resource sharing
p Meeting GoS requirements
Capacity
Blocking probability Cell Loading
?MDE
Channels . . . . .
.
A M R 1 2 . 2 k
C S 6 4
k
Multidimensional ErlangB Model
l MDE is used to calculate the peak load.
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CS Capacity Dimensioning (2)
l Comparison between ErlangB and Multidimensional
ErlangB
Multidimensional ErlangB - Resources shared
High Utilization of resources
ErlangB - Partitioning Resources
Low Utilization of resources
l ErlangB allocate the resource according to the peak load of each service.
Different service are separate, they cannot share the resource.
l MDE considers the probability that different service reach the peak load at the
same time is very low, then the services can share the same resource, and
decrease the resource requirement.
l If there is only one service, MDE is the same with ErlangB.
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Best Effort for Packet Services
l PS Services:
p Best Effort
p Retransmission
p Burst Traffic
l PS will use the spare load apart from that used by CS
Total Load
CSPeak Load
CS Average Load
Load occupied by CS
Load occupied by PS
L o a d
Time
l Best effort means that the packet service can utilize the resource that is
available. PS service can be considered as BE service.
l Retransmission of PS = BLER/(1-BLER)
l PS traffic burst is a method to ensure the QoS, it is obtained from simulation
based on time delay requirement.
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Capacity Dimensioning
l Average load:
l Peak load:
p Query the peak connection through ErlangB table
j j j LoadFactor Trafficd AverageLoa ×=
∑= N
jTotal d AverageLoad AverageLoa1
j j j LoadFactor PeakConn PeakLoad ×=
)( jTotal PeakLoad MDE PeakLoad =
l Where:
p AverageLoad j
is the average load for service j
p For the total average load, the result is the sum of AverageLoad for
different service
p PeakLoadj is the peak load for service j
p For the total peak load, we should calculate it by MDE. The result is
lower than the sum of PeakLoad for different service, Because it
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Case Study (1)
l Common parameters:
p Maximum NodeB transmission power: 20W
p Subscriber number per Cell: 800
p Overhead of SHO (including softer handover): 40%
p Retransmission of PS is 5%
p R99 PS traffic burst: 20%
p Activity factor of PS is 0.9
p Power allocation for CCH is 20% in downlink
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Case Study (2)
l Traffic Model, GoS and load factors:
4.21%
4.99%
1.18%
Load Factors (UL)
0
0
50
0.001
0.02
UL
N/A0PS384 (Kbit)
5.94%N/A100PS128k (Kbit)
2.96%N/A100PS64k (Kbit)
4.65%2%0.001CS64k (Erl)
0.83%2%0.02AMR12.2k (Erl)
Load Factors (DL)GoSDL
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Case Study (2)
l Uplink Average Load l Downlink Average Load
AMR12.2k:
0.02*800*1.18%=18.88%
CS64k:
0.001*800*4.99%=3.99%
PS64k:
50*800*(1+5%)*(1+20%)/0.9/64/360
0*4.21%=1.02%
CS&PS uplink average load:
18.88%+3.99%+1.02%=23.89%
AMR12.2k:
0.02*800*(1+40%)*0.83%=18.59%
CS64k:
0.001*800 *(1+40%)* 4.65%=5.2%
PS64k:
100*800*(1+5%)*(1+40%)*(1+20%)/0.9
/64/3600*2.96%=2.01%
PS128k: 2.02%
CS&PS downlink average load:
18.59%+5.2%+2.01%+2.02%=27.82%
l The difference between UL and DL is: DL should consider the soft handover,
but UL doesn"t need.
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Case Study (3)
l Uplink Peak Load l Downlink Peak Load
AMR12.2k:
Traffic=0.02*800=16Erl
Peak Conn= ErlangB(16, 2%)=24
Peak Load=24*1.18%=28.32%
CS64k:
Traffic=0.001*800=0.8Erl
Peak Conn= ErlangB(0.8, 2%)=4
Peak Load=4*4.99%=19.96%
CS Peak Load: 42.53%
AMR12.2k:
Traffic=0.02*800*(1+40%)=22.4Erl
Peak Conn= ErlangB(22.4, 2%)=31
Peak Load=31*0.83%=25.73%
CS64k:
Traffic=0.001*800 *(1+40%)=1.12Erl
Peak Conn= ErlangB(1.12, 2%)=5
Peak Load=5*4.65%=23.25%
CS Peak Load: 42.33%
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Contents
3. Capacity Dimensioning
3.1 R99 Capacity Dimensioning
3.2 HSDPA Dimensioning
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HSDPA Capacity Dimensioning (1)
l HSDPA Capacity Dimensioning
p The purpose is to obtain the required HSDPA power to satisfy
the cell average throughput.
p HS-DSCH will use the spare power apart from that of R99
Dedicated channels (power controlled)
Common channels
Power usage with dedicated
channels channels
t
Unused power
Power
HS-DSCH with dynamic power allocationt
Dedicated channels (power controlled)
Common channels
HS-DSCH
Power 3GPP Release 99 3GPP Release 5
Pmax-R99
l HSDPA Capacity Dimensioning
p to obtain the average cell throughput
p based on HSDPA simulation result
p considering the gain of HSDPA scheduling
p the maximum data rate is limited by the available power, available codes
resource and UE capacity
p higher cell target load can be available for HSDPA
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HSDPA Capacity Dimensioning (2)
l Capacity Based on Simulation
p to simulate Ior/Ioc distribution in the
network with certain cell range
p to simulate cell throughput distribution
based on Ec/Io distribution in the cell
l Dimensioning Procedure
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
3.50%
4.00%
4 . 2 2
2 . 9 8
2 . 0 4
1 . 3 9
0 . 9 6
0 . 6 6
0 . 4 5
0 . 3 1
0 . 2 1
0 . 1 4
0 . 1
0 . 0 7
0 . 0 5
0 . 0 3
0 . 0 2
0 . 0 1
0 . 0 1
0 . 0 1 0 0 0 0
Ioc/Ior
D i s t r i b u t i o n p r o b a b i l i t y
DU Cell coverage Radius=300m
Conditions of Simulation
ü Channel model-TU3
ü 5 codes
Simulation
Ec/Io distribution
Ior/Ioc distribution
Cell coverageradius
Cell averagethroughput
Ec/Io =>throughput
HSDPA Power Allocation
l During the HSDPA capacity dimensioning procedure, we know the Cell
Coverage Radius (obtained from the coverage planning) and Cell Average
Throughput (obtained from the traffic model), and we want to get the HSDPA
Power Allocation based on simulation.
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Case Study
l Input parameters
p Subscriber number per cell: 800
p HSDPA Traffic model: 1200kbit per subs
p HSDPA Retransmission rate: 10%
p The power for HS-SCCH: 5%
p Cell radius: 1km
l HSDPA cell average throughput:
l The needed power for HS-DSCH including that for HS-SCCH is 18.38%
kbps293%)01(1*3600
1200*800=+
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Case Study
l Uplink Total Load of the Cell :
p CS Peak Load: 42.53%
p CS&PS average load: 23.89%
l Downlink Total Load of the Cell :
p CS Peak Load: 42.33%
p CS&PS average load: 27.82%
p HSDPA load is 18.38%
p CCH load: 20%
66.20%%. MAX
Load Load Load Load Load Load CCH HSDPAavg PS avg CS peak CS DLtotal cell
=++=
+++= −−−−
%20%)38.188227%,33.42(
,max _
%4%. MAX
Load Load Load Load avg PS avg CS peak CS ULtotal cell
53.2)8923%,53.42(
,max _
==
+= −−−−
l Base on this capacity dimensioning result, we can check whether the cell load
of the network is beyond the network target. If it is, we should adjust the cell
radius.
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Overview
l Definition of a CE:
p A Channel Element is the base band resource required in the NodeB
to provide capacity for one voice channel, including control plane
signaling, compressed mode, transmit diversity and softer handover.
l NodeB Channel Element Capacity
p One BBU3900
n UL 1,536 CEs with full configuration
n DL 1,536 CEs with full configuration
l Due the technical features of the WCDMA, compared with the 2G systems such
as GSM, the RNC and Node B present enormous capacity. For example, for the
fully configured NodeB, the number of channels of one carrier is 128, which is
more than 10 times of that supported by a TRX of GSM. One uplink processing
unit of our NODEB has the processing capacity of 128 12.2kbps voice channels.
One 3*1 WCDMA BTS is equivalent to the GSM sites of one S10/10/10. At the
beginning of the WCDMA network construction, so high a capacity is not a
necessity, and only a portion of it is required (e.g., 10%). If we offer the
quotation based on the maximum hardware channel capacity of TRX like the
GSM, it will make the operators incur enormous cost and mismatch the user
quantity. To reduce the initial investment, the operator is bound to pay the
equipment price to the supplier according to the actual use capacity, and,
subsequently, pay more equipment prices with the increase of the user quantity.
This way, the operator will reduce the initial investment and mitigate the risks.
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Huawei Channel Elements
Featuresl Channel Elements pooled in one NodeB
l No need extra R99 CE resource for CCH
p reserved CE resource for CCH
l No need extra CE resource for TX diversity
l No need extra CE resource for Compressed Mode
p reserved resources for Compressed Mode
l No need extra CE resource for Softer HO
l HSDPA does not occupy R99 CE resource
p separate module for HSDPA
l HSUPA shares CE resource with R99 services
l No additional CE resource for AGCH RGCH and HICH
l Softer HO CE: 3900 series NodeB doesn"t need extra CE resource, but 3800
series NodeB needs extra CE resource
l HSUPA shares CE resource with R99 services: that means the HSUPA E-DCH shares
CE resource with R99 services
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CE Dimensioning Flow
),( _ _ _ _ _ _ _ HSUPAUL AUL PS UL AverageCS UL Peak CS Total UL CE CE CE CE CE MaxCE +++=
),( _ _ _ _ _ _ _ DL A DL PS DL AverageCS DL Peak CS Total DL CE CE CE CE MaxCE ++=
Dimensioning Start
CS Average CE
Channel Elements per NodeB
Dimensioning End
--Subscribers per NodeB--Traffic model
PS Average CECS Peak CE (MDE) HSPA CE
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CE Mappings for R99 Bearers
810PS384k
45PS144k
45PS128k
23PS64k
23CS64k
11AMR12.2k
DownlinkUplinkBearer
Channel Elements Mapping for R99 Bearers
l The mapping relationship of Channel Elements consumption for each bearer is
based on Uplink 2-way diversity
l In the case of uplink 4-way diversity, the CE consumption is shown below:
p Bearers CE (4-way diversity)
p AMR12.2k 2
p CS64k 4
p PS64k 4
p PS128k 8
p PS384k 16
l Detailed and recently updated data should be referred to the newest issued
notice of "UMTS RAN Product Specification".
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R99 CE Dimensioning Principle
l Peak CE occupied by CS can be obtained through multidimensional
ErlangB algorithm
l Average CE needed by CS and PS depend on the traffic of each service,
i.e.
l Average CE = Traffic * CE Factor
CE
Resources .
.
.
. . .
A M R 1 2 . 2 k
C S 6 4 k
Multdimensional ErlangB Model
Total CE
CS Peak CE
CS Average CE
CE occupied by CS
CE occupied by PS
and HSPA
C E
Time
CE resource shared
among each service
l The CE dimensioning principle is similar with capacity dimensioning.
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HSDPA CE Dimensioning
l In uplink, no CE consumption for HS-DPCCH if corresponding UL
DCH channel exists
l In uplink, CE consumed by one A-DCH depends on its bearing
rate
l In downlink, A-DCH is treated as R99 DCH
l No additional CE needed for HS-DSCH and HS-SCCH
One HSDPA link need
one A-DCH in uplink and
downlink respectively
H S - D S C H H S - S C C H H S - D P C C H
Associated Dedicated Channels
Site 1 Site 2
l HSDPA channels doesn"t occupy R99 CE resource, but we should calculate the A-
DCH CE.
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CE Mappings for HSDPA Bearers
1 CE---
DL A-DCH
(DPCCH)
---3 CEUL A-DCH
(DPCCH)
---0 CEHS-DPCCH
0 CE---HSDPA Traffic
DownlinkUplinkTraffic
HSDPA Channel Elements Consumption
l HSDPA Traffic:
p Separate dedicated module processing HSDPA Traffic so HSDPA traffic
does not occupy any R99 CE resource.
p HS-DSCH and HS-SCCH does not affect base band capacity for R99
services.
l HS-DPCCH
p HS-DPCCH doesn"t consume any R99 Channel Element since its base
band resource is reserved in BBU module.
l UL A-DCH (DPCCH)
p PS64k is recommended to bear uplink user data, TCP acknowledgement
and signaling.
p One PS64k consumes 3 CE in uplink.
l DL A-DCH (DPCCH)
p A-DCH bears DL signaling control.
p A-DCH can be beared on HSDPA since RAN10.0.
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Case Study (1)
l Input Parameters
p Subscribers number per NodeB: 2000
p Overhead of SHO: 30%
p R99 PS traffic burst: 20%
p Retransmission rate of R99 PS: 5%
p PS Channel element utilization rate: 0.7
p Average throughput requirement per user of HSDPA: 400kbps
p HSDPA traffic burst is 25%
p Retransmission rate of HSDPA is 10%
0
0
50
0.001
0.02
UL
N/A1200HSPA (kbit)
N/A80PS128k (kbit)
N/A100PS64k (kbit)
2%0.001CS64k (Erl)
2%0.02AMR12.2k (Erl)
GoSDLTraffic Model
l In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH.
That means 50kbits for UL PS64k includes the R99 UL DCH and HSDPA UL A-
DCH.
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Case Study (2)
l Uplink CE Dimensioning l Downlink CE
DimensioningAMR12.2:
Traffic =0.02*2000*(1+30%) = 52Erl
Peak CE =ErlangB(52,0.02)*1= 63 CE
Average CE =52*1=52 CE
CS64:
Traffic =0.001*2000*(1+30%) = 2.6Erl
Peak CE =ErlangB(2.6,0.02)*3 = 21 CE
Average CE =2.6*3=9 CE
Total peak CE for CS: 80CE
Total average CE for CS: 52+9=61CE
AMR12.2:
Traffic =0.02*2000*(1+30%) = 52Erl
Peak CE =ErlangB(52,0.02)*1 = 63CE
Average CE =52*1=52CE
Traffic of VP:
Traffic =0.001*2000*(1+30%) = 2.6Erl
Peak CE =ErlangB(2.6,0.02)*2 =14CE
Average CE =2.6*2=6CE
Total peak CE for CS: 74CE
Total average CE for CS: 52+6=58CE
l Different with capacity dimensioning, the UL CE dimensioning should consider
the soft handover.
l For the peak CE, we should use MDE to calculate.
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l Uplink CE Dimensioning l Downlink CE
DimensioningCE for PS64k:
Total CE for R99 PS services:
4CE
4CE 5%)(1*20%)(1*30%)(1*3*36000.7 64
50*2000=+++
CE for PS64k:
CE for PS128k:
Total CE for R99 PS services:
4+4=8CE
CE for HSDPA A-DCH:
3CE10%)(1*%)52(1*1*3600*400
1200*2000=++
4CE5%)(1*20%)(1*30%)(1*2*3600*0.7*64
100*2000=+++
4CE5%)(1*20%)(1*30%)(1*4*3600*0.7*128
80*2000=+++
Case Study (3)
l In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH,
therefore it is no need to calculate the HSDPA UL CE
l For the HSDPA DL A-DCH CE, strictly speaking, it can perform soft handover.
But usually the CE requirement is low, so in Huawei strategy, the soft handover
is not considered.
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Case Study (4)
l Uplink CE Dimensioning l Downlink CE Dimensioning
Total CE Total CE
CE MAX
CE CE
CE MaxCE
UL Average PS UL AverageCS
UL Peak CS Total UL
80)461,80(
)
,(
_ _ _ _
_ _ _
=+=
+
=
CE 743)858 Max(74,
)CE CE CE
,CE ( MaxCE
DL _ A DL _ PS DL _ Average _ CS
DL _ Peak _ CS Total _ DL
=++=
++
=
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Contents
1. Traffic Model
2. Interference Analysis
3. Capacity Dimensioning
4. CE Dimensioning
5. Network Dimensioning Flow
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Network Dimensioning Flow
UL/DL Link Budget
Cell Radius=Min (RUL, RDL)
UL/DL Capacity
Dimensioning
Satisfy Capacity Requirement?
Capacity Requirement
Adjust Carrier/NodeBNo
Yes
CE Dimensioning
Output NodeB Amount/
NodeB Configuration
Coverage Requirement
start
End
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