Umts

WCDMA Radio Network Planning and
Optimization

Song Pengpeng

Contents
>

WCDMA Fundamentals(including link budget fundamentals)

>

Radio Resource Utilization

>

Coverage and Capacity issues

>

Cell deployment

>

WCDMA Radio Network Planning(including WCDMA-GSM Coplanning issues )

>

Co-existing TDD & FDD modes

Presentation Title — 2

All rights reserved © 2004

WCDMA Fundamentals
>

WCDMA network infrastructure

>

WCDMA radio interface protocol architecture

>

WCDMA link level characteristics & indicators

>

WCDMA link budget analysis



WCDMA Fundamentals
>

WCDMA Network infrastructure
Data General

C
N

Data General

Data General

M
SC
Iu

Iu
RC
N
I ub

RC
N

I ur
I ub

I ub

I ub

U AN
TR

U
u

U
E


N
odeB

N
odeB

U
E

N
odeB

N
odeB

U
E

U
E

WCDMA Fundamentals
>

WCDMA Radio Interface protocol architecture
R o Bear er s
adi

R o R
adi
esour ce C r ol
ont
Subl ayer ( R C
R)

Layer 3
Packet D a
at
C
onver gence
Pr ot ocol ( PD P)
C

Si gnal l i ng
R o Bear er s
adi

R o Li nk
adi
C r ol
ont
R
LC
Subl ayer ( R )
LC

R
LC

R
LC

R
LC

Layer 2

Logi cal C
hannel s

M a Access C r ol Subl ayer ( M )
edi
ont
AC
Tr anspor t C
hannel s

Physi cal l ayer ( PH
Y)


Layer 1

WCDMA Fundamentals
>

Mapping between Trch and PHY channels
Transport Channels

Physical Channels

DCH

Dedicated Physical Data Channel (DPDCH)
Dedicated Physical Control Channel (DPCCH)

RACH

Physical Random Access Channel (PRACH)

CPCH

Physical Common Packet Channel (PCPCH)
Common Pilot Channel (CPICH)

BCH

Primary Common Control Physical Channel (P -CCPCH)

FACH

Secondary Common Control Physical Channel (S -CCPCH)

U
ser dat a t r ansm ssi on,
i
DH D HH D HC H..
C , SC , S- SC , PC .

PCH
Synchronisation Channel (SCH)
DSCH

Physical Downlink Shared Channel (PDSCH)
Acquisition Indicator Channel (AICH)
Access Preamble Acquisition Indicator Channel (AP-AICH)

N
odeB

Paging Indicator Channel (PICH)

Si gnal i ng and C r ol
ont
C
hannel s, e. g.
BC , PC , FAC , R H . .
H H
H AC .

CPCH Status Indicator Channel (CSICH)
Collision-Detection/Channel-Assignment Indicator
Channel (CD/CA-ICH)
HS-DSCH

High Speed Physical Downlink Shared Channel (HS-PDSCH)
HS-DSCH-related Shared Control Channel (HS-SCCH)
Dedicated Physical Control Channel (uplink) for HS-DSCH (HS-DPCCH)



U
E

WCDMA Fundamentals
WCDMA parameters
Parameters
Chip rate
Frame length
Modulation
Bandwidth
Vocoder
Base synchronization
Power control rate

WCDMA
3.84 Mcps
10 or 2 ms
Downlink: QPSK;
Uplink: HPSK
5 MHz
Algebraic Code Excited
Linear Prediction Coder(ACELP)
Asynchronization
1500 Hz
Unique scrambling code (Gold code)

Cell identification

WCDMA link level indicators
indicators

Formularization

BLER
BER

Average block error rate calculated for the transport blocks
Information bit error rate

R

User information bit rate
Eb W Prx
= ⋅
Uplink:
N0 R I
Energy per bit divided by noise spectral density(including interference
Eb W
Prx
Downlink: N = R ⋅ I ⋅ (1 − α ) + I + P
power density)
0
own
oth
N

Eb/No

(Eb/No) divided by
processing gain

Ec/Io
Ec/Ior

OVSF code
Channelization code

i=

I

G=
G(Geometry factor)

I oth
I own

I own
I oth + PN

Average Power Rise
Noise Rise
Power Control
headroom

(Average required
received Eb/Io without fast PC)(average required received
Eb/Io with fast PC)

Macro Diversity
Combining Gain


Comments


The received chip energy relative to the total power spectral density;
always used on CPICH,AICH and PICH.
The transmitted energy per chip on a chosen channel relative to the
total transmitted power spectral density at the base station.
Other-to-own-cell received power ratio

Mostly used in downlink, G reflects the distance of the MS from the BS
antenna. Atypical range is from –3 dB to 20 dB, where –3 dB is for the
cell edge.
The difference between the average transmitted power and the average
received power in low multi-path diversity channels
The ratio of the total received wideband power to the noise power.

Also referred as “TPC headroom” or “multipath fading margin”
The reduction of the required Eb/No per link in soft or softer handover
when compared to the situation with one radio link only.

WCDMA Radio Network Planning---Example of link budget
analysis
>

RF link budget components:



WCDMA Radio Network Planning---Example of link
budget analysis
Example of RLB for 12.2 kbps voice service(uplink,120km/h,in-car users,VA channel with soft handover)
Transmitter(mobile)
Max. Tx power[dBm]
Mobile antenna gain[dBi]
Body loss[dB]
Equivalent Isotropic
Radiated power
(EIRP)[dBm]
Receiver(base station)
Thermal noise density
[dBm/Hz]
Base station receiver
noise figure[dB]
Receiver noise density
[dBm/Hz]
Receiver noise power
[dBm]

Max_path_loss=Ptx_EIRP - Prx_receiver_sensitivity
-Lrx_cable+ Grx_antenna

Allowed_propagation_loss=Max_path_loss
-Log_normal_fading_margin
+soft_handover_margin
-in_car_loss


Interference margin[dB]
Receiver interference
power[dBm]
Total effectve noise +
interference [dBm]
Processing gain[dB]
Required Eb/No[dB]
Receiver sensitivity[dBm]
Base station antenna
gain[dBi]
Cable loss in the base
station[dB]
Fast fading margin[dB]
Max.path loss[dB]

21
0
3

a
b
c

18

d=a+b-c

-174

e

5

f

-169
-103.2
3

g=e+f
h=g+10*log(3840000)
I

-103.2

j=10*log(10^((h+i)/10)-10^(h/10))

-100.2
25
5
-120.2

k=10*log(10^(h/10)+10^(j/10))
l=10*log(3840/12.2)
m
n=m-l+k

18
2
0
154.2

Coverage probability[%]
95
Log normal fading
constant[dB]
7
Propagation model exponent
3.52
Log normal fading margin
[dB]
7.3
Soft handover gain[dB]
3
In-car loss[dB]
8
Allowed propagation loss
for cell range[dB] All rights reserved
141.9

o
p
q
r=d-n+o-p-q

s
t
u

© 2004
v=r-s+t-u

Closely related with the loading of the cell which
subsequently affects the coverage. For coveragelimited cases a smaller interference margin is
suggested,while in capacity-limited cases a larger
interference margin should be used. Typical value
for the interference margin in the coverage-limited
cases are 1.0-3.0 dB corresponding to 20-50%
loading.

A headroom for mobile station to maintain
adequate closed loop fast power control. This
applies especially to slow-moving pedestrian
mobiles.Typical values are 2.0-5.0 dB for slowmoving mobiles(*)
the margin required to provide a specified
coverage availability over the individual cells.
For a 95% coverage with a standard shadowing
deviation of 6.0dB and path loss model with
n=3.6 we need a shadowing margin of
approximately 6.0dB
handovers give a gin against slow fading by
reducing the required log-normal fading margin;it
also gives an additional macro diversity gain
against fast fading by reducing the required
Eb/No due to the effect of macro diversity
combining.

(*) *“modeling the impact of the fast power control on the WCDMA uplink”, sipila,K., Laiho-Steffens,J.,Jasberg,M. and Wacker.A, Proc VTC99’ Spring Huston,Texas,May 1999 pp.1266-1270

RADIO RESOURCE UTILIZATION
>

Radio Resource Management

Basic RRM functions
* Power Control

To adjust the transmit powers in upilnk and
To adjust the transmit powers in upilnk and
downlink to the minimum level required to
downlink to the minimum level required to
enshure the demanded QoS
enshure the demanded QoS

Power Control

Takes care that a connected user is handed
Takes care that a connected user is handed
over from one cell to another as he moves
over from one cell to another as he moves
through the coverage area of a mobile
through the coverage area of a mobile
network.
network.

Handover
Control

* Handover Control
* Congestion Control
* Resource Management

Let users set up or reconfigure a radio
Let users set up or reconfigure a radio
access bearer(RAB) only if these would not
access bearer(RAB) only if these would not
overload the system and if the necessary
overload the system and if the necessary
resources are available.
resources are available.
Takes care that a system temporarily going
Takes care that a system temporarily going
into overload is returned to a noninto overload is returned to a nonoverloaded situation.
overloaded situation.
To handle all non-realtime traffic,allocate
To handle all non-realtime traffic,allocate
optimum bit rates and schedule
optimum bit rates and schedule
transmission of the packet data, keeping the
transmission of the packet data, keeping the
required QoS in terms of throughput and
required QoS in terms of throughput and
delays.
delays.


To control the physical and logical radio
To control the physical and logical radio
resources under one RNC;to coordinate the
resources under one RNC;to coordinate the
usage of the available hardware resouces
usage of the available hardware resouces
and to manage the code tree.
and to manage the code tree.

Admission
control

Load control

Packet data
scheduling

Congestion Control

Resource
Manager

To ensure
To ensure
that the
that the
network stays
network stays
within the
within the
planned
planned
condition
condition

RADIO RESOURCE UTILIZATION---power control(1)
>

UMTS Power Control(PC) summary



RADIO RESOURCE UTILIZATION---power control(2)
>

Uplink/Downlink inner- and outer- loop power control
DP

MO
C_

DE

QE
nd
C a e t S IR
n
mi
RM
CR
al
rg
ax/
UL
ern
UL al ta
,
E
/m
nt
i a l OD
): actu
Ei
thm
nit
Hz
ori
+U
L i PC_M
UL
00
fic
alg
f
-1
,D

tra
PC
IR ep,D
(1 0
ss,
t
tS
ep ,
FP
h lo
rge PC_s
_st
Ht
C
ta
DC
, pa
TP
ial L T
t
L
CP
ini er, D
,U
RS
P:
or s
BA pow
ICH
a ct
N RL
nf
-CP
gai
o ,P
c/I
UL
E
,
ER
ICH
BL
-CP
ge t
,P
C)
tar
ER
pP
BL
:DL
l oo
C
u al
n er
RR
act
(In
C:
CH
Hs
C
RR
DC
DP
DP
on
nd
H+
ma
CC
co m
DP
C
on
TP
PC
/DL
L

u
v al

es,

an
me

s

Iub

U

Uu

NodeB
UE

SIR estimates Vs target Sir
UL TPC commands

DL outer loop PC
SIR_step=f(BLER or BER)
SIR target management
SIR estimate vs. target SIR
 DL TPC commands



SRNC

UL outer loop PC
SIR_step=f(BLER or BER)
SIR target management
MDC and splitting

RADIO RESOURCE UTILIZATION---handover control
Soft-Handover:Example of Soft Handover Algorithm
Addition window

Event 1A: A P-CPICH enters the reporting range

SR C
N

I ub

Event 1B: A P-CPICH leaves the reporting range
 NA

10 ⋅ log10 M old ≤ W ⋅ 10 ⋅ log10  ∑ M i  + (1 − W ) ⋅ 10 ⋅ log10 M Best − ( R1b − H 1b 2)


 i =1


N
odeB 1

Event 1C: A non-active PCPICH becomes better than drop window
an active one
Event 1D: change of best cell. Reporting event is
triggered when any P-CPICH in the reporting range
becomes better than the current bet one plus an
optional hysteresis value.
Event 1E: A P-CPICH becomes better than an
absolute threshold plus an optional hysteresis value.
Event 1F: A P-CPICH becomes worse than an
absolute threshold minus an optional hysteresis value.

Measurement
Quantity

I ub

M o D ver si t y
acr
i
com ni ng
bi

d1
an n
m
m io
co i ss
C m 1
TP ans nk
tr li

 NA

10 ⋅ log10 M new ≥ W ⋅ 10 ⋅ log10  ∑ M i  + (1 − W ) ⋅ 10 ⋅ log10 M Best − ( R1a − H 1a 2)


 i =1


T
∆

CPICH 1

TP
tr Cc
an om
s
m
l i m s and
i
nk si 2
2 on

>

U i n SH
E
O

N
odeB 2

T
∆

T
∆

As_Th + As_Th_Hyst

AS_Th – AS_Th_Hyst

As_Rep_Hyst

CPICH 2

CPICH 3


Time

Cell 1 Connected

Event 1A
Add
⇒ Cell 2

Event 1C ⇒
Replace Cell 1 with Cell 3

Event 1B ⇒
Remove Cell 3

RADIO RESOURCE UTILIZATION---PC and SHO
conclusion
>

Bonding of SHO and PC(based on the fact that SHO gain is dependent on

the PC efficiency)
• SHO gain depends on the type of channel and the degree of PC
imperfection.It is usually higher with imperfect PC.
• SHO diversity can reduce the PC headroom,thus improving the coverage.
• The transmit and receive power differences as a result of SHO
measurement errors and SHO windows can affect the PC error rate in
uplink,reducing the uplink SHO gains.
• In uplink, SHO gain is translated into a decrease in the outer-loop PC’s
Eb/No target.



RADIO RESOURCE UTILIZATION---congestion
control
>

Air interface load definition(load control principles)
•

Uplink
• Wideband power-based uplink loading
ηUL =

prxTotal = I own + I oth + PN

1

ηUL = ∑
Throughput-based uplink loading
W
k 1+
ρ k ⋅ Rk ⋅ν k
Downlink
• Wideband power-based downlink loading

•

•

I own + I oth
where
PrxTotal

ηDL =
•

PrxTotoal
Ptx max

Throughput-based downlink loading
N

η DL =


∑R
k =1

N

k

Rmax

or

ηDL = [(1 − α ) + iDL ] ⋅ ∑ (
k =1


ρ k ⋅ Rk ⋅ν k
)
W

⋅ (1 + i )

control (cont’d)

>

Congestion control---keep the air interface load
under predefined thresholds
•
•
•

>

C
ongest i on C r ol
ont
Adm ssi on
i
cont r ol

Admission control---handling all the new traffic
Load control---managing the situation when
system load has exceeded the threshold
Packet scheduling---handling all the non-realtime traffic

Load cont r ol

Packet dat a
schedul i ng

Admission control
•

Wideband power-based admission control
For uplink, an RT bearer will be admitted1if
P
where
∆I ≈ rxTotal ⋅ ∆L and ∆L =
W
1+
1 −η
ρ ⋅ R ⋅ν
– For downlink, an RT bearer will be admitted if
–

•

Throughput-based admission control

PrxNC + ∆I ≤ PrxT arg et
PrxTotoal ≤ PrxT arg et + PrxOffset
PtxNC + ∆P ≤ PtxT arg et
PtxTotal ≤ PtxT arg et + PtxOffset

For uplink, it follows ηoldUL + ∆L ≤ ηthresholdUL
– For downlink, it follows ηoldDL + ∆L ≤ ηthresholdDL
–



control (cont’d)
>

Packet scheduling
•
•

Packet schedul i ng al gor i t hm

Time division scheduling
Code division scheduling

Pr ocess C
apaci t y r equest s

C cul at e l oad budget f or
al
packet schedul i ng

Yes

N
o
N
o

Load bel ow t ar get
l evel ?

O l oad t hr eshol d
ver
exceeded?
Yes
I ncr ease l oadi ng

D ease l oadi ng
ecr

Al l ocat e/ m f y/ r el ease
odi
r adi o r esour ces



RADIO RESOURCE UTILIZATION---Code Planning
>

Code planning
•
•

>

Code allocation is under the control of RNC.
Code tree may become “fragmented” and code reshuffling is
needed(arranged by RNC).

Code allocation
•
•

Scrambling and spreading code allocation for uplink(by UTRAN)
Scrambling and spreading code allocation for downlink
• Downlink channelisation code allocation (by UTRAN)
• Downlink scrambling code planning
• 512 scrambling codes subdivided into 64 groups each of
eight codes



RRM optimization --- SHO optimization(1)
>

Addition window optimization
Determines the relative difference of the cells
at the MS end that are to be included in the
active set
D aded
egr
per f or m
ance
• Optimized so that only the relevant cells are
due t o t oo
hi gh l evel
in the active set
•

di f f er ence of
t he si gnal s
i n AS

Too w de
i
SH ar ea
O

U
nnecessar y
br anch
addi t i on

I ncr eased
SH
O
over head

Too sm l
al
SH ar ea
O

M C gai n
R
r educt i on

R
educed U
L
capaci t y

Fr equent AS
updat es

t oo hi gh

I ncr easi ng
si gnal l i ng
over head

R evant
el
cel l s r em
oved
f r om AS

I ncr eased
Tx pow s
er

Addi t i on
w ndow
i
t oo l ow


I ncr eased
BS and M
S
Tx Pow
er


R
educed D
L
capaci t y

R
educed U
L/
D capaci t y
L

R
educed D
L
and U
L
capaci t y

>

Drop window optimization
•

Slightly larger than the addition window
D aded
egr
per f or m
ance
due t o t oo
hi gh l evel
di f f er ence of
t he si gnal s
i n AS

R
educed U
L
capaci t y

I ncr eased BS
and M Tx
S
Pow
er

Frequent and
delayed Hos (cells
ping-pong in the
active set)

I ncr eased
M Tx pow
S
er

I ncr eased BS
Tx pow
er

R
educed D
L
capaci t y

U
nnecessar y
br anches
st ay i n AS

Too l ar ge
SH
O
over head

t oo l ow

Fr equent
Hs
O

I ncr eased
si gnal i ng
over head

t oo l ow

R evant
el
cel l s r em
oved
f r om AS

I ncr eased
Tx pow s
er

t oo hi gh

dr op
w ndow
i



R
educed U
L/
D capaci t y
L

>

Replacement window optimization
•

Determines the relative threshold for MS to trigger the reporting Event 1C.
Too high: slow branch replacement and thus non-optimal active set
– Too low: ping-pong effect with unnecessary SHOs
–

t oo hi gh

Act i veset
subopt i m
al

r epl acm
ent
w ndow
i
t oo l ow

Exceut i on of
unnecessar y
Hs
O


M Tx pow
S
er
i ncr ease

U l oad
L
i ncr ease

I ncr eased
cal l dr op or
bl ock r at e

BS Tx pow
er
i ncr ease

D l oad
L
i ncr ease

R
educed cal l
set up success
r at e

I ncr eased
si gnal i ng
over head


R
educed D U
L/ L
t ot al cel l
t r af f i c

>

Maximum active set size optimization
D aded
egr
per f or m
ance
due t o t oo
hi gh l evel
di f f er ence of
t he si gnal s
i n AS

t oo bi g

M AS
ax
si ze

Possi bl e
unnecessar y
br anch addi t i on
Pr event
necessar y sof t
H br anch
O
addi t i on

I ncr eased
M Tx pow
S
er

I ncr eased
BS Tx pow
er

I ncr eased SH
O
over head

R
educed U
L
capaci t y

R
educed D
L
capaci t y


R
equi r e
hi gher Tx
pow t o a M
er
S

D aded D
egr
L
BLER
per f or m
ance

R
equi r e hi gher
Tx pow f r om
er
a M
S

t oo sm l
al

D aded U
egr
L
BLER
per f or m
ance


I ncr eased
cal l dr op/
bl ock r at e

RADIO RESOURCE UTILIZATION --- SHO
optimization conclusion
>

SHO overhead target level should be 30%~40%.
•
•
•
•
•

Addition window & Drop window optimization should be tuned first
Change the active set size if needed
Drop timer value is secondary
P-CPICH power could be the final parameter for SHO optimization(not
recommended!)
Optimization of active set weighting coefficient to give a stable SHO
performance



Coverage and Capacity issues
>

Coverage-limited & Capacity-limited scenarios …

>

Coverage & Capacity enhancement methods
•
•
•
•
•
•
•
•

Additional carriers and Scrambling codes
Mast Head Amplifiers
Remote RF Head Amplifiers
Repeaters
Higher-order Receiver Diversity
Transmit Diversity
Beam-forming
Sectorization



Coverage and Capacity issues---Coverage
>

How can coverage be deduced from link budget? link budget Max Path
Losscell rangecoverage

>

Generally, service coverage is uplink limited but system capacity may be
limited by either uplink or downlink.
Service type
Speech Data
Data
Uplink bit rate(kbps)
12. 2
64
144
Maximum transmit power(dBm)
21
21
21
Antenna gain(dB)
0
0
2
Body loss(dB)
3
0
0
Transmit EIRP(dBm)
18
21
23
Processing gain
25 17. 8 14. 3
Required Eb/No(dB)
4
2
1. 5
Target loading (%)
50
50
50
Rise over thermal noise(dB)
3
3
3
Thermal noise density(dBm/Hz)
- 174 - 174 - 174
Receiver noise figure(dB)
3
3
3
Interference floor(dBm/Hz)
- 168 - 168 - 168
Receiver sensitivity(dBm)
- 123. 1 - 117. 9 - 115
Rx antenna gain(dBi)
18. 5 18. 5 18. 5
Cable loss(dB)
2
2
2
Fast fading margin(dB)
3
3
3
Soft handover gain(dB)
2
2
2
Isotropic power required (dBm) - 138. 6 - 133. 4 - 130
Allowed propagation loss(dB)
156. 6 - 154. 4 153. 4


Data
384
21
2
0
23
10
1
50
3
- 174
3
- 168
- 111. 1
18. 5
2
3
2
126. 6
149. 6


Hint: It’s critical to decide
whether a specific area
should be planned for high
data rate service coverage
or not

Different service
type(voice@12.2kbps,
data@64,144,384kbps
)supported with
different link budget
and thus different
coverage range!

Coverage and Capacity issues---Capacity
>

An uplink-limited scenario --- when the maximum uplink load is reached prior
to the base station running out of transmit power.

>

An downlink-limited scenario --- when the base station runs out of transmit
power and additional users cannot be added without modifying the site
configuration.
Identifying the limited link:

>

Uplink limited
Limiting factor

Downlink limited

Uplink cell load

BTS transmit power
Planned to a high uplink cell load
Low BTS transmit power
capability
Greater traffic on the downlink
BTS transmit power at maximum
Uplink cell load not at maximum
Improve downlink load equation
Improve downlink link budget

Planned to a low uplink cell load
High BTS transmit power capability
Common reasons Relatively symmetric traffic
BTS transmit power not at maximum
Indications
Uplink cell load at maximum
Solution


Improve uplink load equation


Coverage and Capacity issues---Enhancement
methods

>

Coverage & Capacity enhancement methods
•

Additional carriers and Scrambling codes
System capacity is maximized by sharing the power across the available
carriers,e.g, two carriers configured with 10W can offer significantly greater
capacity than a single carrier configured with 20W does.
– In downlink-limited capacity scenario,the number of supported users
depends on the downlink channelisation code orthogonality. It is especially
true when higher data rate service is supported in micro-cell.
–

•

Mast Head Amplifiers
To reduce the composite noise figure of the bse station receiver subsystem.
– But brings bad effects when in downlink-limited scenario.
–

•

Remote RF Head Amplifiers
To allow the physical separation of base station’s RF and baseband
modules.
– Maintaining the same service coverage performance while increasing cell
capacity.
– Difference between remote RF head amplifiers and repeaters .
–



methods(cont’d)
>

Coverage & Capacity enhancement methods(cont’d)
•

Repeaters
Used for extending the coverage area of an existing cell, low-cost and ease
of installation but introduces delay.
– Slight capacity loss in uplink-limited scenario.
– Applicable in scenarios where clear cell dominance can be achieved such as
in rural areas or in tunnels.
–

Remote RF head amplifier
Locating the entire logical
cell at a locatio normally
requiring a long feeder run

Repeater

Extending the coverage
Application
of an existing logical cell
Complete Rx and Tx chain for
Hardware at
Tranmit power amplifiers
both uplink and downlink
remote location and receiver front ends
directions
Connection to BS Optical link
Usually a radio link
Function
Normal RF functions of the BS Non-intelligent retransmission



methods(cont’d)
>

•

Higher-order Receiver Diversity
To overcome both the impact of fading across radio channel and increase the
resulting signal-to-interference ratio.
– Improves uplink performance,especially beneficial for low-speed mobile
terminals.
–

•

Transmit Diversity
Downlink transmit diversity mandatory in 3GPP specifications,e.g. closedloop mode and open-loop mode.
– Most effective when time- and multipath- diversity is inadequate,e.g. for
capacity gain in micro-cell scenario.
–

•

Beam-forming
An effective technique for improving the downlink performance,especially
in environment with a low transmit element.
– High mobile terminal complexity requirement and non-standard
functionality configuration.
–



methods(cont’d)
>

•

Sectorization
A general technique to increase cell capacity where antenna selection is
critical.
– May require correspondingly high quantity of hardware with highly
sectorisation.
– Usage
–

for typical
Micro- cell
deployment

Sectorisation level Application
1 sector
Microcell or low-capcity macrocell
Sectored microcell or macrocell
2 sector
providing roadside coverage
Standard macrocell configuration
3 sector
providing medium capacity
Not commonly used but may be
4 or 5 sector
chosen to support a specific traffic scenario
6 sector
High-capacity macrocell configuration



for typical
macro-cell
deploymen
t

CELL DEPLOYMENT
>

Hierarchical Cell Structure(HCS) with two or more (FDD) carriers
•
•
•

>

Continuous macro-cells to provide full coverage as an “umbrella” layer.
Micro-cells to accommodate hot-spots with increased capacity and
higher bit rates in limited areas.
Typical air interface capacities are about 1Mbps/carrier/cell for a threesectored macro BS and 1.5Mbps/carrier/cell for a micro BS.

Example of WCDMA network evolution
An “umbrella” macro cell
is best suited for highmobility users

f1

f1

f1

f1

f1

f1

f2

Capacity
enhancement
f1
f2

Micro layer provides a
very high capacity in a
limited area

f2
f1

f2

f2

f2

f2

f1
f2

f 1, f 2 f 1, f 2 f 1, f 2 f 1, f 2 f 1, f 2 f 1, f 2

C i nuous m o l ayer
ont
acr
w t h f r equency f 1
i
ont
acr
i
Sel ect ed ar eas w t h m cr o
i
i
cel l s w t h f r equency f 2
i
ont
acr
i
C i nuous m cr o l ayer
ont
i
i
N m o l ayer
o acr
Bot h f r equenci es
cont i nuousl y f 1, f 2
used i n m cr o l ayer
i

CELL DEPLOYMENT
>

Case study of frequency reuse in micro- and macro- networks
Reference scenario

f2
f1

f1

f1

f1

Reuse of micro frequency in macro layer

f 1, f 2
f1

f1

f1

f1

macro carrier reuse is not
worth while when micro-cells
locates near macro-cells! Reusing a micro carrier
Continuous macro layer with frequency f2
on all macro-cells does
Continuous micro layer with frequency f1
not bring any
improvements in network
performance!
Continuous macro layer with frequency f1 and f2

Reuse of macro frequency in micro layer

f2


f 1, f 2 f 1, f 2 f 1, f 2 f 1, f 2

Continuous micro layer with frequency f1 and f2

Reuse of macro frequency in selected micro cells

f2
f1

f 1, f 2 f 1, f 2


f1

selected microcells reusing macro frequency f2


Reusing a macro carrier
on all micro-cells can
support 10% more users
than the reference
scenario,but extra
Power Amplifier needed!
Micro-cells do not
benefit from the other
carrier reused from
macro-cells if they
still have unused
capacity on their own
carrier!

WCDMA Radio Network Planning
>

overview

>

Dimensioning

>

Detailed planning

>

Optimization aspects

>

Adjacent carrier interference

>

WCDMA & GSM Co-Planning



WCDMA Radio Network Planning---Network planning
process overview
Definition

N w
et ork
Conf i gurat i on
and
Dm
i ensi oni ng

R
equi rem s
ent
and st rat egy
f or coverage,
qual i t y and
capaci t y per
servi ce


Planning and Implementation

Coverage
pl anni ng
and si t e
sel ect i on

P
ropagat i on
m
easurem s
ent
coverage
predi ct i on

Capaci t y
R
equi rem s
ent

P
aram er
et
pl anni ng

N w
et ork
O i m sat i on
pt i

T fic
raf
di st ri but i on
al l ow
ed
bl ocki ng/
qeui ng Syst em
f eat ures

A
rea/Cel l
speci f i c
set t i ng

Survey
M
easurem s
ent

E ernal
xt
Int erf erence
A ysi s
nal
Si t e
acqui si t i on
Coverage
opt i m sat i on
i

O&M

Ident i f i cat i on
A
dapt at i on


H
andover
St rat egi es
M m
axi um
l oadi ng

O her R M
t
R

St at i st i cal
perf orm
ance
anal ysi s

Q i ty
ual
E f i ci ency
f
A l abl i t y
vai

WCDMA Radio Network Planning ---Dimensioning(1)
>

What is Dimensioning?
--- to estimate the required site density and site configurations for
the area of interest
• Radio Link Budget(RLB) and coverage analysis;
• Capacity estimation
• Estimation of the amount of base station hardware and
sites,radio network controllers,equipment at different interfaces
and core network elements
• Knowledge of service distribution,traffic density, traffic growth
estimates and QoS requirements are essential



>

Coverage analysis:
•

for the single-cell case*:

•

where a = σ ⋅ 2 b = σ ⋅ 2 10
wherer is the received level at the cell edge,n is the propagation
P
constant, x0 is the average signal strength threshold and σ is the standard
deviation of the field strength and erf is the error function.
for a typical macro-cellular environment
Fu =

1 
1 − 2ab
1 − ab 
⋅ 1 − erf ( a ) + exp(
) ⋅ (1 − erf (
))
2
2 
b
b


x0 − Pr

10 ⋅ n ⋅ log e

using Okumura-Hata model, the following formular gives an example for an
urban macro-cell with base station antenna height of 25m, mobile station
antenna height of 1.5m and carrier frequency of 1950 MHz:

–

Lp = 138.5 + 35.7 ⋅ log10 ( r )

where r is the maximum cell range and Lp is the max path loss.

*

“Microwave Mobile Communications”, Jakes,W.C, John Wiley& Sons, 1974,126pp



>

Capacity estimation
•
•
•
•

>

WCDMA capacity and coverage are connected in terms of interference
margin.
Knowledge and vision of subscriber distribution and growth is a must.
Site configurations such as channel elements,sectors and carriers and site
density can be determined.
Capacity refinement may be obtained in late network optimization.

RNC dimensioning
•

RNC dimensioning limited factors:
Maximum number of cells(a cell is identified by a frequency and a
scrambling code)
– Maximum number of Node B under one RNC
– Maximum Iub throughput
– Amount and type of interfaces(e.g. STM-1,E1)
–



>

RNC dimensioning(cont’d)
•

The number of RNCs needed to connect a certain number of cells
numRNCs =

•

The number of RNCs needed according to the number of BTSs to be
connected
numBTSs
numRNCs =

•

numCells
cellsRNC ⋅ fillrate1

btsRNC ⋅ fillrate2

the number of RNCs to support the Iub throughput
numRNCs =

voiceTP + CSdataTP + PSdataTP
⋅ numSubs
tpRNC ⋅ fillrate3

>

Supported traffic (upper limit of RNC processing ability)

>

Required traffic(lower limit of RNC processing ability)

>

RNC transmission interface to Iub



WCDMA Radio Network Planning ---Detailed
Planning(1)
>

Using Radio Network Planning(RNP) tools
•

•

>

To find an optimum trade-off between
quality,capacity and coverage criteria for all
the services in an operator’s service
portfolio.
Integrated tools for dimensioning,network
planning and optimization.

I ni t i al i ze i t er at i ons
I ni t i al i sat i on phase

Upl i nk i t er at i on st ep
Downl i nk i t er at i on st ep

Using Static simulator *
•

G obal i ni t i al i zat i on
l

Com ned UL/ DL i t er at i on
bi

Static simulator flow
Post pr ocessi ng
G aphi cal out put s
r
Cover age anal ysi s
Post Pr ocessi ng phase

* “Static simulator for studying WCDMA radio network planning issues”,Wacker.A, Laiho-steffens.J,Sipila.K
and Jasberg.M,VTC99’Spring pp2436-2440



Planning(2)
>

Example of RNP tool workflow
Defining service
requirements

Creating a plan/
load maps

Importing/creating
and editing sites and
cells

A plan usually includes parameter settings for
A plan usually includes parameter settings
the planned network elements such as:
the planned network
•Digital map& its properties
•Digital map& its properties
•Target planning area propagation models
•Target planning area propagation models
•Antenna models
•Antenna models
•Selected radio access technology
•Selected radio access technology
•BTS types and site/cell templates
•BTS types and site/cell templates
Importing
measurements

Site location,site ground height number of
cells and antenna direction

Importing/
generating and
refining traffic layers
Traffic planning:
Traffic planning:
• Bearer service type and bit rate,
• Bearer service type and bit rate,
• average packet call size and retransmission rate,
• average packet call size and retransmission rate,
• busy-hour traffic amount and traffic density for
• busy-hour traffic amount and traffic density for
each service,
each service,
• mobile list and WCDMA calculation
• mobile list and WCDMA calculation

To verify that the planned coverage, capacity and QoS criteria
To verify that
can be met with te current network deployment and parameter
can be met with te current network deployment and parameter
settings:
settings:
• Run UL/DL iterations to calculate tx powers for MS and BS
• Run UL/DL
• Snapshot analysis for interference and coverage estimation
• Snapshot analysis
estimation
• Optimizing dominance
• Optimizing dominance


Link loss calculation

WCDMA
calculations

Analysis

Propagation model
tuning

Propagation models:
Propagation models:
•Macro cell---Okumura-Hata model
•Macro cell---Okumura-Hata model
•Micro cell---Walfisch-Ikegami model
•Micro cell---Walfisch-Ikegami model

A WCDMA cell template may include cell
A WCDMA cell template may include cell
layer type,channel model,Tx/Rx diversity
layer type,channel model,Tx/Rx diversity
options,power settings, maximum acceptable
options,power settings,
load, propagation model,antenna infomation
load, propagation model,antenna infomation
and cable losses
and cable losses

Quality of Service

Neighbour cell
generation

reporting

Cite/BTS hardware template may include:
Cite/BTS hardware template may include:
•Maximum number of wideband signal
•Maximum number of wideband signal
processors
processors
•Maximum number of channel units
•Maximum number of channel units
•Noise figure
•Noise figure
•Available Tx/Rx diversity types
•Available Tx/Rx diversity types

Planning(3)---UL/DL iteration steps
i ni t i al i zat i on

G obal i ni t i al i zat i on
l

S
et ol dThr eshol ds t o t he
def aul t / new cover age t hr eshol ds

I ni t i al i ze del t a_C I _ol d
/
Al l ocat e t he C C pow s
PI H
er

I f no convergence

C cul at e new cover age
al
t hr eshol ds

C cul at e t he r ecei ved Per ch l evel s and
al
det er m ne t he best ser ver i n D
i
L

C
heck U l oadi ng and possi bl y m
L
ove
M t onew ot her car r i er or out age
Ss
/

C cul at e t he M sensi t i vi t i es
al
S
D er m ne t he SH connect i ons
et
i
O

E
val uat e U br eak cr i t er i on
L
C cul at e i ni t i al TX pow s f or al l l i nks
al
er

C
onnect M s t o best ser ver , cal cul at e
S
needed M TxPow
S
er and SH gai ns
O

C cul at e t ar get C I ’ s
al
/

C cul at e adj ust ed M Tx
al
S
pow s, check M s f or out age
er
S

U i t er at i on st ep
L

C cul at e new I =I _ot h/ I _ow
al
n

C
heck C C Ec/ I o cal cul at e t he
PI H
C I f or each connect i on
/
cal cul at e C I f or each M
/
S

D i t er at i on st ep
L

C
heck U and D br eak
L
L
cr i t er i a
I f not f ul f i l l ed

conver gence

UL iteration steps

Adj ust TX pow s of
er
each r em ni ng l i nk
ai
accor di ng t o del t a_C I
/

f ul f i l l ed

P
ost pr ocessi ng

D
Presentation Title — 41EN

U
pdat e del t a_C I _ol d
/

Post pr ocessi ng

EN
D

DL iteration steps

>

WCDMA Radio Network Planning ---Adjacent Channel
Interference

Adjacent Channel Interference(ACI) situation
•

Adjacent Channel Leakage Power Ratio(ACLR)
–

•

Adjacent Channel Selectivity(ACS)
–

•

the ratio of the transmitted power to the power measured in an adjacent channel
the ratio of the receive filter attenuation on the assigned channel frequency to the
receive filter attenuation on the adjacent channels

Adjacent Channel Protection(ACP)
–

The ratio of adjacent channel power received by the base station as adjacent
R
x
R
x
channel interference power
0dB

0dB

BS AC
P

UL adjacent channel
interference situation

BS AC
P
f1

f2
BS sel ect i vi t y

w ed si gnal
ant

Tx

N
odeB@r equency1
f

f2

w ed si gnal
ant

Tx

0dB

0dB

N
odeB@r equency2
f

M l eakage
S

M AC
S LR

M AC
S LR
f1


f1


f2

f1

f2

WCDMA Radio Network Planning ---Adjacent Channel
Interference
Tx
0dB

0dB

BS AC
LR

DL adjacent channel
interference situation

Tx

BS AC
LR
f1

f2
BS l eakage

w ed si gnal
ant

R
x

N
odeB@r equency1
f

f2

w ed si gnal
ant

R
x

0dB

0dB

N
odeB@r equency2
f

M sel ect i vi t y
S

M AC
S P

M AC
S P
f1

>

f1

f2

f1

f2

Worst ACI cases---when a macro MS is coming too close to a micro
BS
•

Minimum Coupling Loss(MCL)
the smallest path loss between the transmitters and receivers
– For a micro BS and MS, MCL is about 53dB
– For a macro BS and MS, MCL is about 70dB
–



WCDMA Radio Network Planning ---Example of Worst
ACI case
>

Worst ACI case when sites of different operators not co-located

For downlink scenario, supposing the micro BS is transmitting with a
minimum power of 0.5W(27dBm); then the received interference at the
MS in the adjacent channel is

O at or 1 M o C l
per
acr
el

27dBm − 53dB ( MCL) − 32.7dB ( ACS ) = −58.7dBm

Assuming speech service (processing gain of Gp=25dB) with an Eb/No
requirement at the Ms of 5dB and an allowed noise rise in the macro cell
of 6 dB, the maximum allowed propagation loss Lp to keep the uplink
connection working is

L p = 21dBm − 5dB + 25dB − ( −103dBm + 6dB ) = 138dB

if we further consider a DL Tx Eb/No requirement of 8dB, the transmit
power would need to be p = −58.7dBm + 8dB − 25dB + 138dB
tx

O at or 2 M cr o C l
per
i
el
hi gh TX pow
er

For uplink scenario, with a maximum MS power of 21dBm,
53dB for MCL to the micro BS and coupoing between the
carriers of C=32.7dB,the received level at the micro BS and be
estimated as 21dBm − 53dB − 32.7dB = −64.7dBm
if the background noise level is dBm, the micro BS would
suffer a 38.4 dB noise rise form one macro user, which is
located in the radio sense at the MCL distance form the micro
BS, i.e. such a macro user would completely block the micro
BS.

O at or 2 M cr o C l
per
i
el

= 62.3dBm

si gnal
si gnal

AC
I

D
ead Zone
f or O at or 1
per

This simple example shows that clearly in these
cases the DL is the weaker link, i.e. before coming
too close to a micro BS, the connection of a macro
BS will be dropped due to insufficient DL power and
it cannot block the micro BS.

O at or 1
per
Assuming ACS and ACLR of values 33dB and 45dB
M
S
respectively, the coupling C between the carriers can
be calculated as:
−33 / 10


C = −10 ⋅ log10 (10


AC
I

O at or 1 M
per
S
M TX pow
ax.
er

+ 10−45 / 10 ) = 32.7dB

WCDMA Radio Network Planning ---Optimization
aspects(1)
>

Guidelines for Radio Network Planning to avoid ACI in multioperator environment
•

Base station and antenna locations
Co-locate BSs
– Deploy the antennas in a position as high as possible
–

•

Base station configuration
Optimum antenna beam-width
– “desensitisation”---increasing the noise figure
–

•
•
•

Inter-frequency handovers
Inter-system handovers
Guard bands



WCDMA Radio Network Planning ---Optimization
aspects(2)
>

Site locations and configurations
•
•
•

>

Antenna installations(cable losses)
Optimum antenna tilting angle and correct antenna selection
Optimum sectorisation regarding to number of users and SHO
overhead.*

Usage of mast head amplifier(MHA)**
•
•
•

Used in uplink direction to compensate for the cable losses
Improved uplink coverage probability
May have negative effect on downlink performance in case of downlinklimited scenario

* “The impact of the base station sectorisation on WCDMA Radio Network Performance”,A.Wacker,J.Laiho-Steffens,K.Sipila,K.Heiska,VTC99’Amsterdam.
** “The impact of the Radio Network Planning and Site Configuration on the WCDMA Network Capacity and Quality of Service”,J.Laiho-Steffens,A.Wacker,
P.Aikio,VTC2000



WCDMA-GSM Co-Planning Issues
>

Examples of maximum path losses with existing GSM and WCDMA system
GSM900/ GSM1800/ WCDMA/ WCDMA/ WCDMA/
speech
speech
speech
144kbps 384kbps
Mobile transmission power[dBm]
Interference margin[dB]
Fast fading margin[dB]

4

Base station antenna gain[dBi]
5

Body loss[dB]

6

Mobile antenna gain[dBi]
Relative gain from lower
frequency compared to UMTS
7

frequency[dB]

Maximum path loss[dB]

21

21

-110

-124

-117

-113

0

2

2

2

2

2

2

2

16

18

18

18

18

3

3

21

2

2

30

1

Receiver sensitivity[dBm]

33
-110

1

3

3

0

0

0

2

2

11

1

164

154

156

154

150

1
WCDMA sensitivity assuems 4.0dB base station noise figure and Eb/No of 5dB for 12.2kbps speech,1.5dB for 144kbps and 1.0dB for 384kbps
data.GSM sensitivity is assumed to be -110dBm with receive antenna diversity.
2

WCDMA interference margin corresponds to 37% loading of the pole capacity.An interference margin of 1.0dB is reserved for GSM900 because the
small amount of spectrum in 900MHz does not allow large reuse factors.
3
The fast fading margin for WCDMA includes the macro diversity gain against fast fading.
4
The atenna gain assumes three-sector configuration in both GSM and WCDMA.
5
The body loss accounts for the loss when the terminal is close to the user's head.
6


A 2.0dBi antenna gain is assumed for the data terminal.

7
The attenuation in 900MHz is assumed to be 11.0dB lower than in UMTS band and in GSM1800 band 1.0dB lower than in UMTS band.

WCDMA-GSM Co-Planning Issues---interference
issues
>

Interference between the two system is the main issue
•

Radio frequency issue
Second harmonics of GSM900 could probably fall into WCDMA uplink
band
– Third-order inter-modulation products of PCS 1800 could be problematic
–

Second-order harmonic
distortion from GSM900
falling into WCDMA band

f GSM=950~960M z
H
G 900
SM
935~960M z
H

U A U A FD
TR
TR
D
TD 1920~1980
D
1900~1920M z
H



f

WCDMA-GSM Co-Planning Issues ---interference
issues
•

Interference mechanisms from GSM system to WCDMA system
Adjacent Channel Interference(ACI):depends on Tx/Rx filter and spatial and
spectral distance between the own and adjacent carrier,the cell type and the
power levels used.
– Wideband Noise(WB):from all out-of-band emission components.
– Cross-modulation(XMD): depends on non-linearity of the MS receiver,the
duplex isolation and the transmitting mobile power.
XMD is
proportional to
proportional to
– Inter-Modulation Distortion(IMD):caused by non-linearities of RF
the square of
the square of
transmitting
components of transmitter or receiver.
transmitting
–

W M B
CD A S

G B
SM S
W em ssi on
B i
f r om G BS
SM

Typically in
Typically in
micro-cells
micro-cells
and could be
and could be
reduced by
reduced by
guard band.
guard band.

C ossm
r
odul at i on
( XM )
D

Third-order IMD with
mixture of products of
the GSM carrier
frequencies f1 and f2:
2f1-f2 or 2f2-f1

AC f r om
I
G BS
SM
AC t o W D A BS
I
CM


I M at t he
D
WD A M
CM S

power and very
power and very
sensitive to the Tx
sensitive to the Tx
power of the MS!
power of the MS!

WCDMA-GSM Co-Planning Issues
Eval uat e t he qual i t y of
t he exi st i ng 2G net w k
or

Space avai l abl e f or onet o- one r euse

Antenna sharing and co-located
sites could be preferable.

Assur e t he cover age f or
al l W D A ser vi ces
CM

U ban ar ea
r
D i ne t r af f i c
ef
di st r i but i on r ul es
bet w
een syst em
s

D i ne handover r ul es
ef
bet w
een syst em
s

R com ned 2G and
un
bi
W D A anal ysi s
CM


G
SM

WD A
CM

r ur al ar ea

G
SM

WD A
CM

Handover
GSM WCDMA for
capacity extension or
service optimization


G
SM

G
SM

G
SM

WD A
CM
Handover WCDMA-GSM
for coverage extension

Co-existing TDD & FDD modes ---UTRA TDD mode
>

Some key parameters for the UTRA FDD and TDD modes

Frame structure
Frame length
Chip rate
Uplink spreading factors
Number of parallel UL
codes per user
Downlink spreading factors
Number of parallel DL
codes per user
Modulation

Power control update rate
Handover
Dynamic channel allocation
Intra-cell interference
cancellation


UTRA FDD
15 slots/frame
10 ms
3.84 Mcps
4~512

UTRA TDD
15 slots/frame
10 ms
3.84 Mcps
1~16

4~512

Rather low
spreading factors
makes it inadequate
to reuse all the
timeslots in all the
cells.That is,network
must control which
slots and directions
are used in which
cells.

1 or 2
1~ 16

1~6
QPSK

1500Hz
soft and hard
N/A
support for advanced
receivers at base station

1~16
QPSK
theretically up to 800Hz;in
practice, only 100Hz in DL
and 100Hz or possibly 200Hz
in UL
hard only
slow and fast
support for joint detection


Not as fast as to
follow fast fading
pattern!

Co-existing TDD & FDD modes---Example of TDD RLB
uplink/downlink

Voice
Voice
NRT data NRT data
Example TDD link budget for 12.2kbps 12.2kbps 128kbps 128kbps
uplink(RxD=receive diversity) RxD
No RxD RxD
No RxD
Transmitter(mobile)
Max.Tx Power(dBm)
21
21
24
24
MS antenna gain(dBi)
2
2
2
2
Body loss(dB)
3
3
0
0
EIRP(dBm)
20
20
26
26
Receiver(base station)
Number of used slots in TDD
1
1
1
1
-174
-174
-174
-174
Base station receiver noise
figure(dB)
5
5
5
5
Desensitisation
0
0
0
0
Receiver noise density
(dBm/Hz)
-169
-169
-169
-169
Receiver noise power(dBm)
-103.2
-103.2
-103.2
-103.2
Interference margin(dB)
8
8
8
8
power(dBm)
-95.9
-95.9
-95.9
-95.9
Total effective noise
+interference(dBm)
-95.2
-95.2
-95.2
-95.2
Processing gain(dB)
12
12
2.4
2.4
Required Eb/No(dB)
1.7
8.6
0.3
6.4
-105.5
-98.6
-97.3
-91.2
BS antenna gain(dBi)
4
4
4
4
Cable loss in the base
station(dB)
0
0
0
0
Fast fading margin
(TPC headroom) (dB)
6.3
6.3
3.4
3.4
Max.path loss(dB)
123.2
116.3
123.9
117.8



Example TDD link budget for
downlink(No TxD)

Voice NRT data
12.2kbps 128kbps

Transmitte r(mobile)
Max.Tx Power(dBm)

24

24

BS antenna gain(dBi)

4

4

Cable loss in BS(dB)

0

0

28

28

1

1

EIRP(dBm)
Receiver(mobile)
Number of used slots in TDD

GP =

-174
-174
Mobile station receive r noise
Wfigure(dB) _ in _ slot − midamble − guard _ period
k chips
9
9

⋅ ⋅
RReceiver noise density(dBm/Hz) _ slot -165
15
chips _ in

-165

Receiver noise power(dBm)

-99.1

-99.1

Interference margin(dB)
power(dBm)
Greatereffective difference
Total Eb/No noise
between with or without RxD!
+interference(dBm)

8

8

-91.9

-91.9

-91.1

-91.1

Processing gain(dB)

12

2.4

Required Eb/No(dB)

9.4

6.7

-93.7

-86.8

2

2

3

0

5.5

3.1

115.2

113.7

Mobile antenna gain(dBi)

Smaller Max path loss than that
Body loss(dB)
of FDD scenario TDD cells
Fast fading margin
have smaller radius!
(TPC headroom) (dB)
Max.path loss(dB)

Co-existing TDD & FDD modes--- TDD/TDD
interference
>

Interference scenarios

>

TDD-TDD Interference scenarios/solutions
•

MS to MS interference---when MS1 is transmitting while MS2 is

•

BS to BS interference---when BS1 is transmitting while BS2 is receiving

receiving, especially at cell borders.
– Cannot be avoided by network planning,but may benefit from
– DCA and radio resource management
– Power control

depends heavily on BS locations.
– Could be avoided by providing sufficient coupling loss between base
stations
– BSs better be synchronized and of same asymmetry.
–



Co-existing TDD & FDD modes --- TDD/FDD
interference
>

TDD-FDD Interference scenarios/solutions
U A TD
TR
D
U A FD / U
TR
D L
Tx/ R
x

1900

•

1920

Sat ellite

1980

Interference mainly
between TDD and FDD/UL
frequency bands!

U A
TR
TD
D
Tx/ R
x

2010

H
2025 ( M z)

TDD MS to FDD BS
To make FDD/BS less sensitive,especially for small pico cells
– To place BS antenna as high as possible from TDD MSs
–

•

FDD MS to TDD BS
–

•

Inter-frequency or inter-system may be helpful

FDD MS to TDD MS
Use downlink power control of TDD BS to compensate for the interference
from FDD MS
– Inter-system/inter-frequency handover
–



Co-existing TDD & FDD modes
>

UTRA TDD
•
•
•
•
•
•
•

Advantage in the unpaired spectrum operation
Better utilized for asymmetric service at high data rate
Can build stand-alone wide-area TDD network(?) or serve as a separate
capacity-enhancing layer in the network
Lower Max. Path loss compared with FDD scenario
Lower “cell breathing” and thus more stable service coverage
Requires strict synchronization especially in uplink
Low-rate services often goes to code-limited cases while high-rate
services goes to interference-limited cases
From the service point of view, UTRA TDD is most suited for small cells
and high data rate services!



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