dimensioning process

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1 © Nokia Siemens Networks Presentation / Author / Date Dimensioning process MODULE 9 Configuration Planning Configuration Planning Param eter Planning Area/cell specific Handover strategies OtherRRM Site selection and planning PRE- PLANNING DETAILED PLANNING Site acquisition Post-launch optim isation M easurem ent surveys Statistical perform ance analysis Quality Efficiency Availability POST- PLANNING Node-B Configuration Antenna line configuration Pow erbudget PER SERVICE Pre-launch optim isation M easurements Dimensioning Requirem ents and strategy forcoverage, capacity and quality PER SERVICE Netw ork configuration Propagation m easurem ents Coverage prediction Load estim ation Traffic distribution Planned Service and QoS definition Coverage and Capacity Planning

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No Slide TitleDimensioning process
MODULE 9
Dimensioning process
Understand basic steps of dimensioning
To calculate cell loading
Module Contents
Dimensioning process
Module Contents
Dimensioning process
Dimensioning Process Description
Base station configuration selection and power budget calculation for all limiting services
R99 service link budget for selected service(s)
HSDPA link budget with selected cell edge throughput
HSUPA link budget with selected cell edge throughput
Initially with max. load
Capacity evaluation
Antenna height
Evaluate cell range using max system load and link budget for user at the cell edge
Compute cell loading from traffic profile and cell range
Add Carrier/
Coverage limited max. cell range for specified max system load
Cell range known
Dimensioning Process Description
Coverage limited scenario
System loading is lower than the level used initially to compute the cell range
Rise in interference floor used in the link budget calculation was pessimistic
Complete process is repeated with a lower value of system loading
Lower increase in interference floor greater cell range more users in each cell greater actual system loading.
The reduction in system loading used in the link budget calculation is continued until it matches the actual system loading computed by the traffic profile. This then defines the final cell range.
Evaluate cell range using max system load and link budget for user at the cell edge
Compute cell loading from traffic profile and cell range
Add Carrier/
Coverage limited max. cell range for specified max system load
Cell range known
Dimensioning Process Description
Capacity limited scenario
In this case
System loading is greater than the maximum level used initially to compute the cell range
Maximum DL power is exceeded
HSPA throughput (UL or DL) is lower than minimum throughput
Cell capacity must be increased or the cell size decreased
Increase the cell capacity by adding additional carriers
Dedicated HSPA carrier also possible
Reduced cell range fewer users loading the cell
A reduction in cell range is made and the system loading re-calculated
The reduction in cell range is done iteratively until the target load or HSPA throughput is achieved. This then defines the final cell range.
Evaluate cell range using max system load and link budget for user at the cell edge
Compute cell loading from traffic profile and cell range
Add Carrier/
Coverage limited max. cell range for specified max system load
Cell range known
Module Contents
Dimensioning process
Input parameters – overview
Traffic Density Map
QUALITY RELATED
MS Class
Indoor Coverage
Location Probability
Blocking Probability
Gives an Estimation of the Equipment Necessary to Meet the Network Requirements
Network Dimensioning Activities
Capacity Related Input
The number of subscribers, user profile and spectrum available are the main requirements for capacity dimensioning
Traffic forecast should be done by analysing the offered Busy Hour traffic per subscriber for different service bit rates in each rollout phase.
Traffic data:
Codec bit rate, Voice activity
RT data :
Service bit rates
Average throughput (kbps) subscriber during busy hour of the network
Target bit rates
Asymmetry between UL an DL traffic for NRT Services (Downloading 1/10) should be taken into consideration.
Network and Subscribers evolution forecast is also needed.
* © Nokia Siemens Networks Presentation / Author / Date
Capacity Related Input
The traffic figures are broken down into traffic per subscriber and busy hour for each service, separately for uplink and downlink
Asymmetry
HSPA related dimensioning inputs
Required cell edge throughput (HSDPA and HSUPA) is required for the power budget calculation
HSPA coverage
Required total cell throughput
OR
HSPA traffic profile per user as in R99 traffic Total required throughput
Maximum total DL power for HSDPA and max UL load for HSUPA has to be defined
* © Nokia Siemens Networks Presentation / Author / Date
Coverage Related Input
coverage area for each rollout phase
percentage of the area for each morpho-class (DU,U,SU,R)
building penetration loss and fading margin
propagation models for path loss calculation
correction factors for the Propagation Model
Service Scenarios should be defined: which kind of service is to be offered and where
Target coverage area and Coverage Probability for each service type
* © Nokia Siemens Networks Presentation / Author / Date
Quality Related Input
The network dimensioning is focused on fulfilment quality expectations form user point of view. It means that resources should be as efficient as demanding(QoS) are service requirements in dimensioned network.
Blocking Probability is blocking of call attempts due to lack of available resources and for CS Services is usualy between1-2%
In cellular networks the coverage areas of cells overlap and the mobile station is able to connect to more than just one serving cell. If more than one cell can be detected the location probability increases and is higher than determined for single isolated cell. Location probability usually is within the range 90 – 99%. It depends on environment, service and customer requirements and has a big impact on the number of site
Local coverage probability:
received signal level [dBm]
Module Contents
Dimensioning process
Cell Loading Calculation
Evaluate cell range using max system load and link budget for user at the cell edge
Compute cell loading from traffic profile and cell range
Add Carrier/
Coverage limited max. cell range for specified max system load
Cell range known
HSUPA throughput calculation
* © Nokia Siemens Networks Presentation / Author / Date
Cell Loading Calculation – R99 traffic
Traffic per cell is usually defined in terms of Erlang for voice and real time (RT) data services and in terms of kbits/s for non real time (NRT) data
For voice and RT data services the calculations are based upon the Erlang B formula and for NRT data services upon throughput. The two equations are given below.
Voice and RT data:
NRT data:
R is the service bit rate. The blocking probability is typically assumed to be 2%. The throughput is assumed to be 79%. This figure includes the L2 re-transmission overhead of 10% and 15% of buffer headroom to avoid overflow (peak to average load ratio headroom) => (1+0.10) x (1+0.15) = 1.265 => 26.5% overhead => throughput 79%
1. Traffic per Cell
N = traffic channels = trunks
A = Y + B*A
Cell Loading Calculation – R99 traffic
Evaluation of the physical channel requirement per carrier for each service class. This is completed separately for UL and DL.
In the case of the UL,
Initially a single carrier is assumed. This is later increased if there is need to do so for capacity reasons.
In the case of the DL,
Evaluation of interfering channels per cell for each service class. This requires a direct multiplication of the physical channel requirement with the corresponding service activity factor i.e.
1. Traffic per Cell
Cell Loading Calculation – R99 traffic
Where:
m is the number of interfering channels
Eb/No is the target energy per bit to interference spectral density ratio
W is the chip rate
R is the bit rate
MDCgain_UL is the macro diversity gain on the UL due to soft handover
PowerRiseUL is the average increase in transmit power due to power control.
i_UL is the ratio of other to own cell interference.
1. Traffic per Cell
5. Fractional Load
3. Physical Channels
(=traffic channels*SHO)
2. Traffic Channels
The total UL load is obtained by summing the UL fractional loads over all service classes.
Evaluation of the fractional loads for UL & DL. The UL fractional load for a service class is given by:
* © Nokia Siemens Networks Presentation / Author / Date
Cell Loading Calculation – R99 traffic
where,
m is the number of interfering channels
Eb/No is the target energy per bit to interference spectral density ratio
W is the chip rate
R is the bit rate
MDCgain_DL is the macro diversity gain on the DL due to soft handover
Orth_DL is the downlink orthogonality
i_DL is the ratio of other to own cell interference.
1. Traffic per Cell
DL fractional load for a service class is given by:
The total downlink load is obtained by summing the downlink fractional loads over all service classes.
* © Nokia Siemens Networks Presentation / Author / Date
Total base station DL power – R99 traffic
Total DL base station transmit power can be a limiting factor in highly loaded cell
where,
Lserv is the pathloss of user j. The pathloss is defined as total loss from BTS transmitter to the receiver
PCCCH is the total common control channel power
* © Nokia Siemens Networks Presentation / Author / Date
Load Calculation Examples
Load factor for different services has to be calculated separately, total load is then the sum of different services in the cell area
UL/DL fractional load examples are shown in the table below
For example 50 % UL load means on average 50 speech users or about 9 64 kbits/s users/cell in a 3-sector (1+1+1) configuration
Tabelle1
HSDPA throughput
Available HSDPA power can be calculated from the total power equation when DCH traffic load and maximum allowed DL power is known
* © Nokia Siemens Networks Presentation / Author / Date
HSDPA Cell Throughput
The total cell throughput of 1320 kbps
Without any HSDPA traffic, the Rel’99 DCH cell capacity equals
780 kbps
Using 7-8 W for HSDPA, the total cell throughput is increased by a factor 1320/780=1.69
5-code HSDPA 16QAM
HSUPA throughput
The available UL load for HSUPA is calculated when the R99 traffic UL load is known
Max Load HSUPA = Max Cell Load – R99 Traffic Load
Available UL HSUPA load can be converted to HSUPA bit rate by using the UL load equation and EbNo/Bit rate table used also in power budget calculation
* © Nokia Siemens Networks Presentation / Author / Date
HSUPA throughput from available load
Assumptions: Activity = 100%, Little i = 0.65
* © Nokia Siemens Networks Presentation / Author / Date
Module Contents
Dimensioning process
Channel element Calculation
The number of channel elements per BTS are calculated so that first the needed traffic channels per BTS (not sector by sector as in fractional load calculations) is calculated.
This is done per BTS since the Code Channels are in one pool over the whole BTS.
The traffic per BTS is calculated from the calculated number of subscribers per BTS and from the subscriber profile.
Then the necessary traffic channels per BTS per service is calculated by using the same formulas as in previous slides (as well as the number of physical channels).
Next the soft handover overhead is added to the calculated traffic channels to get the number of physical channels per BTS.
note that this soft handover overhead addition is done for both UL and DL.
The channel element need for different services is following
Speech (16 kbit/s) => 1 channel element
64 kbit/s service (RT or NRT) => 4 channel elements
128 kbit/s service (RT or NRT) => 4 channel elements
384 kbit/s service (RT or NRT) => 16 channel elements
Traffic profile per cell
Traffic profile per BTS
Note that the channel element means the same as the hardware channel.
Traffic channels per BTS
Add SHO overhead for UL and DL
Convert the number of physical channels per service into channel elements
* © Nokia Siemens Networks Presentation / Author / Date
Channel element Calculation
Common channel processing
Higher due to optimised traffic channel processing capability
WSPA: 8- channel elements/cell
WSPC: 16 channel elements / 1-3 cells
Required number of channel elements is calculated for UL and DL separately Maximum selected
Channel element includes both UL & DL processing power
With asymmetric services and HSDPA different requirements for UL and DL
Add the needed number of channel elements for signalling
Check the amount of data throughput for the BTS
* © Nokia Siemens Networks Presentation / Author / Date
Channel element Calculation – HSDPA
5 codes, 16 users, 3.6 Mbit/s 32 channel elements of FSPA or WSPC
10-15 codes, 48 users, max. 10.8 Mbit/s One whole FSPA or WSPC
Possible configurations
One FSPA or WSPC per BTS with 5 codes (1-3 cells) 3.6 Mbit/s per BTS
Resources freely shared between cells
One FSPA or WSPC per cell with 5 codes 3.6 Mbit/s per cell
Code Shared HSDPA Scheduler max. 10.8 Mbit/s per BTS
One whole FSPA (64 CE/80 CE*) or WSPC (64 CE) for 1-3 cell
Max. 48 users freely divided between cells, transmit to max. 3 users simultaneously
One FSPA or WSPC per cell with 10-15 codes max. 10.8 Mbit/s per cell
Associated channels have to be taken into account for each HSDPA user
DL associated signaling channel = 1 channel element
UL associated signaling + traffic channel = (depends on UL data rate)
* In RAS06 SW level 80 CE/FSPA
* © Nokia Siemens Networks Presentation / Author / Date
WSPC capacity for DCH and HSDPA, example
INPUTS:
Suppose the Rel99 traffic requires 30 CE in DL and 20 in UL (SHO OH included)
The average number of HSDPA users is assumed to be 5 and associated UL traffic is carried on 64kbps bearer
One WSPC card is allocated for HSDPA
BTS configuration is 1+1+1
RESULT:
Total CEs for traffic + CCHs = 40 +16 =56
HSDPA takes 32 CEs, so totally we need capacity of 56 + 32 = 88 CEs.
For this capacity two WSPC cards is required
* © Nokia Siemens Networks Presentation / Author / Date
Channel element Calculation – HSUPA
The maximum number of HSUPA connections per Node B is 24 while the maximum number per cell is 20
Minimum capacity reserved for HSUPA when the feature is activated is 8 CE
More capacity is dynamically reserved when needed and available from other traffic
Minimum fixed allocation can be reserved Decrease capacity for other traffic
This capacity is reserved in both UL and DL CEs.
# HSUPA users/BTS
Module 9 – Dimensioning process
Capacity and coverage planning Cell range and load
The output on dimensioning process is initial network and site configuration
Number of sites/cell
Nominal antenna height
Erlangs
services and in

For voice and RT data services the calculations are based upon t
he
Erlang B formula and for NRT data services upon throughput. The
two

R is the service bit rate. The blocking probability is typically
assumed to be 2%. The throughput is assumed to be 79%. This
figure includes
peak to average load ratio
headroom)
=>
and cell range
12.2 kbit/s0,97%1,00%
64 kbits/s4,80%6,21%
128 kbits/s8,56%11,07%
384 kbits/s22,89%29,59%
Total Load37,22%47,87%