owp112010 wcdma radio network coverage dimensioning issue1.21

WCDMA Radio Network Coverage Planning

Confidential Information of Huawei. No Spreading Without Permission

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Capacitycoverage (typical case: downlink load balance)

Capacityquality (typical case: lowering BLER through outer loop power control)

Coveragequality (typical case: lowering the data rate of the connections with much path

loss through AMRC)



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3G radio network planning can be divided into three phases. They are shown in above

figure, and consist of dimensioning, pre-planning and cell planning.

According to the above figure, the output result of radio network dimensioning stage

serves as the input condition of the pre-planning, and the pre-planning is based on the

network dimensioning and also checks the network dimensioning result. The site quantity

can be adjusted according to the pre-planning result in order to obtain the reasonable sites.

If the existing sites are considered in the selection of theoretical sites during the pre-

planning, the pre-planning result will be more practical, thus facilitating the cell planning.



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Radio Network Dimensioning is a simplified analysis for radio network

Dimensioning provides the first and most rapid evaluation of the network element number

as well as the associated capacity of those elements. The target of dimensioning phase is

to estimate the required site density and site configurations for the area of interest.

Dimensioning activities include radio link budget and coverage analysis, capacity evaluation

and final estimation of the amount of NodeB hardware and E1, cell average throughput

and cell edge throughput.

Objective:

To obtain the network scale ( approximate NodeB number and configuration)

Method:

Select a proper propagation model, traffic model and subscriber distribution, and

then estimate the NodeB number, coverage radius, E1 number per site, cell

throughput, cell edge throughput and so on.



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The service distribution, traffic density, traffic growth estimates and QoS requirements are

already essential elements in dimensioning phase. Quality is taken into account here in

terms of blocking and coverage probability.



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Wireless network dimensioning intends to obtain the approximate UTRAN scale. Based on

the network dimensioning, geography and traffic distribution, the network is pre-planned

in detail by using planning software and digital map.

Based on the network dimensioning and site information, the initially selected WCDMA

site is imported into the planning software, and coverage is estimated by parameters

setting. Then an analysis is made to check whether the coverage of the system meet the

requirements. If necessary, the height and tilt of the antenna and the NodeB quantity are

adjusted to optimize the coverage. And then the system capacity is analyzed to check

whether it meets the requirement.

Implementation parameters, such as antenna type / azimuth / tilt / altitude / feeder type /

length

Cell parameters, such as transmission power of traffic channel and common channel,

orthogonal factor, primary scrambling code



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Based on the network dimensioning and site information, the initially selected WCDMA BS

is imported into the planning software, and coverage is estimated by setting the cell

parameters and engineering parameters. Then an analysis is made to check whether the

coverage of the system meet the requirements. Then the system capacity is analyzed to

check whether it meets the requirement. If necessary, the height and tilt angle of the

antenna and the BS quality are adjusted to optimize the coverage.



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These graphs are prediction results of Huawei planning tool: U-Net

For the result of coverage prediction, focus on the distribution of best servers and pilot

level. For the small areas with unqualified level, adjust the azimuth and down tilt to

improve the coverage. For the large areas with weak coverage, analyze whether the site

distance is over large:

If yes, add sites to improve coverage.

If no, check whether the configuration of parameters related to coverage

prediction is correct.



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We should consider other factors when we select the backup sites

Commercial factor: rent

Radio propagation factor: situation / height / surrounding /

Implementation factor: space / antenna installation / transmission / power supply



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Simulation is oriented to simulate the running situation of networks under the current

network configuration so as to facilitate decision-making adjustment. Now there are two

system simulation classes: static simulation and dynamic simulation.

Static simulation focus on user behavior such as browsing Internet, call. It would gain the

performance of radio network based on snapshot.

Dynamic simulation focus on detail of user behavior such as duration and data rate of

browsing. It would gain the performance of radio network based on analysis of mobile

subscribers. But it requires higher precision of e-map.

At present, Static simulation is in common use. Monte Carlo simulation is one type of

static simulation.



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Some UEs or terminals are distributed based on a certain rule (such as random even

distribution) at each snapshot

It is required to consider the possibility of multiple connection failure (uplink/downlink

traffic channel maximum transmit power, unavailable channels, low Ec/Io and

uplink/downlink interference



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These graphs are prediction results (based on simulation) of Huawei planning tool: U-Net

The previous predictions (Coverage by transmitter, Coverage by signal level, Overlapping

zones) are based on coverage, the predictions in this slide are based on simulation.



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In the coverage dimensioning, the link is estimated according to elements such as planned

area, network capacity, and equipment performance in order to obtain the allowed

maximum path loss. The maximum cell radius is obtained according to the radio

propagation model and allowed maximum path loss. And then the site coverage area is

calculated. Finally, the site quantity is calculated. Of course, the site quality is only for the

ideal cell status, and some additional sites will be needed in actual terrain environment.



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Link dimensioning intends to estimate the system coverage by analyzing the factors of the

propagation channels of the uplink signal and downlink signal. It is the link analysis model.

If the parameters such as transmit signal power, gain and loss of the transmitter and

receiver, and quality threshold of received signal are known or estimated, the allowed

maximum path loss used for ensuring the quality of received signal can be calculated.



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In network planning, the value should be set according to the UE capacity with lowest

power grade in the commercial network of the operator.

Note that it is possible that a UE supporting high-speed uplink data service (higher than

64kbps) has a higher power grade than a UE supporting only voice and low-speed data

services, for example, power grade 3dBm 24dBm.

With a higher maximum power rating, the maximum path loss is increased accordingly. This allows

the operator to plan cells with a relatively larger coverage.

The UE cable loss, connector loss, and combiner loss are quite negligible, hence a 0 dB loss

is assumed here



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The 0 dBi antenna gain is considered here with respect to the internal antenna of mobile

phones.



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The penetration loss is related to building type, incidence angle of the radio

wave and so on. In the link budget, assume that the penetration loss obey

the Log-Normal distribution. The penetration loss is related to mean value of

penetration loss and standard deviation

When indoor coverage is required to coverage by outdoor macro NodeBs, building

penetration loss needs to be considered. Building penetration loss is related to such factors

as incidence angle of the radio wave, the building construction (the construction materials

and number and size of windows), the internal building layout and frequency. Building

penetration loss is highly dependent on specific environment and morphology and varies

greatly. For instance, the wall thickness in Siberian tends to be larger than that of

Singapore in order to resist coldness and hence the formers building penetration loss is

correspondingly larger.

In addition, sometimes vehicular coverage may be required and consequently vehicular

penetration loss also needs to be included in link budget process. typical vehicular

penetration loss is around 8dB.



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Antenna gain: It refers to the ratio of the square of the actual field of an antenna at a

point in the space to the square of the field of an ideal radiation unit at the same point in

the space, namely power ratio. It is the gain in the main transmit direction. In general, the

gain is related to the antenna pattern. If the central lobe is narrow and the back lobe and

side lobe are small, the gain is high. If the transmit direction is centralized, the antenna

gain is high. For an omnidirectional antenna, the gain in all the directions is the same.

Front-to-back ratio: It refers to the ratio of the maximum gain in the principal direction to

the gain in the reverse direction. It describes the directing feature. If it is high, the directed

receive performance of the antenna is high.

Beam width: It refers to the separation angle between the main transmit direction of the

power and the point with 3 dB of transmit power reduced, and the area is called an

antenna lobe. Tilt: It refers to the tilt angle of a directional plate antennal. It is used to

control interference and improve coverage.

Polarization: The vector direction of the electrical field in the direction with the highest

radiation. A dual polarized antenna can provide diversity over a single antenna, thus saving

one antenna.

In general, there are two or more lobes in an antenna pattern. The largest lobe is the

central lobe, and others are side lobes. The separation angle between the two half-power

points of the central lobe is the lobe width of the antenna pattern, namely, half-power

(angle) lobe width. If the central lobe is narrow, the directivity is high, and the anti-

interference capability is high.



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Radio propagation in the land mobile channel is characterized by multiple reflections,

diffractions and attenuation of the signal energy. These are caused by natural obstacles

such as buildings, hills, and so on, resulting in so-called multi-path propagation.

Furthermore, with the moving of a mobile station, the signal amplitude, delay and phase

on various transmission paths vary with time and place. Therefore, the levels of received

signals are fluctuating and unstable and these multi-path signals, if overlaid, will lead to

fading i.e. short term fading. The mid-value field strength of Rayleigh fading has relatively

gentle change and is called Slow fading i.e. long term fading. And it conforms to

lognormal distribution.

Long term fading the variation of signal level is slow and smooth.

Short term fading the variation of signal level is fast and poignant



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Slow Fading --- Signal levels obey Log-Normal distribution

Propagation models predict only mean values of signal strength , the mean value of signal strength

fluctuates. The deviation of the mean values has a nearly normal distribution in dB, The variation in

mean values is called log-normal fading.

Probability that the real signal strength will exceed the average one on the cell border is around

50%,for higher than 50% coverage probability an additional margin has to be introduced. The

margin is called slow fading margin.

Slow Fading Margin (SFM) is related with coverage probability in cell edge and standard deviation of

slow fading. The equation is described as following:



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The standard deviation is a measured value that is obtained from various clutter types. It basically

represents the variance (log-normally distributed around the mean value) of the measured RF signal

strengths at a certain distance from the site.

Therefore, the standard deviation would vary by clutter type. Depending on the propagation

environment, the log-normal standard deviation can easily vary between 6 and 8 dB or even greater.

Assuming flat terrain, rural or open clutter types would typically have lower standard deviation

levels than the suburban or urban clutter types. This is due to the highly obstructive properties

encountered in an urban environment that in turn will produce higher standard deviation to mean

signal strengths than that experienced in a rural area. Standard Deviation of slow fading is related

with morphology, frequency and environment. For instance:



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Soft Handover --- handover between different NodeBs

Softer Handover --- handover between cells in a NodeB

SHO gain over slow fading is also known as the Multi-Cell gain because in soft handover

more than 1 branch exists and hence the coverage probability increases which would

result in the decreasing of required slow fading margin.

Suppose that soft handover has 2 branches, and the orthogonality of the two radio link

branches on slow fading is 50%. We can calculate the slow fading margin required with

soft handovers based on the former assumptions, and compare it with the slow fading

margin required without soft handover to get the SHO gain over slow fading.

SHO gain over slow fading is dependent on the required area coverage probability, the

propagation path loss slope and the STD. The following table gives the calculated SHO

gain over slow fading and the propagation path loss slope equals to 3.59.



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Fast power control

to enhance weak signal caused by Rayleigh fading

to mitigate interference and enhance the capacity

to promote power utilization efficiency

In WCDMA, user signals should be received at the NodeB with equal power all the time

and for downlink the transmitted TCH power should be as small as possible while

maintaining the required Qos. This implies that fast fading are compensated by the power

control algorithm, which requires additional headroom at both UE and NodeB in order to

let UE and NodeB following the power control commands at cell edge.



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Because of the macro diversity combination, the soft handover reduces the required Eb/No

by a single radio link, which results in additional macro diversity gain.



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Interference margin is the required margin in the link budget due to the noise rise caused

by system load (the noise rise due to other subscribers). The higher the system load is, the

larger the interference margin should be.



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If the W=1Hz, Nth=-174dBm/Hz

If the W=200kHz, Nth=-121dBm/200kHz



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Typical noises are: external sky and electric noise, vehicle start-up noise, heat noise from

inside systems, scattered noise of transistor during operation, intermodulation product of

signal and noise.

Noise figure is used for measuring the processing capability of the RF component for small

signals, and is usually defined as: output SNR divided by unit input SNR.

NF

Si

Ni

So

No



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For common services, the bit rate of voice call is 12.2kbps, the bit rate of video phone is

64kbps, and the highest packet service bit rate is 384kbps(R99). After the spreading, the

chip rate of different service all become 3.84Mcps.



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For instance:

Service BLER Channel Model Uplink Eb/N0 Downlink Eb/N0

AMR12.2k 1.00% TU3 5.4dB 7.8 dB

RA120 4.5 dB 8.3 dB

CS64k 0.10% TU3 2.8 dB 6.3 dB

RA120 2.8 dB 6.8 dB

CS64k 1.00% TU3 2.5 dB 5.4 dB

RA120 2.3 dB 6 dB



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In case of multi-path propagation, certain energy will be detected by the RAKE

receiver, and become interference signals. We define the orthogonal factor to

describe this phenomenon. It is obtained through simulation, and related to

environment type and cell radius.



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Continuous coverage target service requirement with specific coverage probability should

be given for R99

Cell edge throughput requirement with specific coverage requirement should be given for

HSDPA



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The cell total transmit power is the constant resources. The DL power consists of the

following three parts:

Power of the HSPA DL physical channel (HS-PDSCH, and HS-SCCH)

Common channel power

DPCH power



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Fast power control

For R99, power control margin should be considered

For HSDPA, the maximum transmission power for HS-PDSCH is the remaining

power excluding R99 power and power margin, and no power control margin

SHO gain

For R99, SHO gain should be considered

For HSDPA, only hard handover, no SHO gain

HSDPA related parameters should be configured when simulation

Max number of HS-PDSCH channel

Min number of HS-PDSCH channel

HSDPA power allocation, dynamic or fixed

HS-SCCH power allocation, dynamic or fixed

Max number of HSDPA users

Scheduling Algorithm



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Single carrier for HSDPA and R99

Advantages

Maximum resource utilization efficiency

Save cost

Disadvantages

Handover between HSDPA cell and R99 cell

Two carriers for HSDPA and R99

Advantages

Fewer inter-frequency handover for HSDPA user

Disadvantages

High cost



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If operator wants to upgrade HSDPA from R99, R99 should be met first, and HSDPA

should not affect the R99.

If operator setups R99 and HSDPA directly, R99 and HSDPA requirement should be met at

the same time.



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DL Coupling Loss :

PL_DL: Downlink path loss

Lf_BS: cable loss of NodeB

Ga_antenna: Gain of UE antenna and NodeB antenna

Lb: Body loss

SFMNSHO: Slow fading margin without soft handover

Lp: Penetration loss

Cell edge Ec/No:

PHS-DSCH : total power of HS-DSCH channel

: non-orthogonality factor

: neighbor cell interference factor

: downlink load factor including R99 and HSDPA service

Pmax : max transmission power of downlink

Nt : thermal noise power spectral density , typical value is -108.16dB

NF : receiver noise figure of UE, typical value is 7dB

f

DL



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The theoretical maximum throughput is decided by the number of HSDPA codes.

For HSDPA , soft handover gain and fast fading margin should not be considered in link

budget , since neither power control nor soft handover in HS-PDSCH channel



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The step is present below:

According to the Cell Radius comes from R99 dimensioning, the Downlink Path

Loss can be calculated

According to the Downlink Path Loss , the Downlink Coupling Loss can be

calculated

According to the Downlink Coupling Loss and HS-DSCH Power, Cell Edge Ec/No

can be calculated

According to the Cell Edge Ec/No and simulation result, Cell Edge Throughput can

be calculated



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According to the Cell Edge Throughput and simulation result, Cell Edge Ec/No can

be calculated

According to the Cell Edge Ec/No and HS-DSCH Power, the Downlink Coupling


According to the Downlink Coupling Loss, the Downlink Path Loss can be

calculated

According to the Downlink Path Loss and and Propagation Model, HSDPA Cell

radius can be calculated



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According to the Cell Radius comes from R99 dimensioning, the Downlink Path


According to the Downlink Path Loss , the Downlink Coupling Loss can be

calculated

According to the Cell Edge Throughput and simulation result, Cell Edge Ec/No can

be calculated

According to the Downlink Coupling Loss and Cell Edge Ec/No , HS-DSCH Power

can be calculated



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owp112010 wcdma radio network coverage dimensioning issue1.21

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