08 Fdd Lte Radio Icic 36
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Transcript of 08 Fdd Lte Radio Icic 36
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FDD-LTE Radio ICIC
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Contents
ICIC Introduction
ICIC theory and scheme
ICIC Performance
ICIC Application
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What Is ICIC?
ICIC (Inter cell Interference Coordination) A set of techniques that based on FFR/SFR( fractional
frequency reuse/soft frequency reuse) and power
control/allocation, adaptive scheduling. It can be used to
suppress ICI( inter cell interference) and to achieveimproved coverage area compared to universal frequency
reuse( frequency reuse factor is equal to one) network
deployment and keep proper system spectrum efficiency
simultaneously.
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Interference coordination & management
Overview
There are three main interference coordination &management methods
Interference coordination & management methods for handling mono-frequency interference
Mono-frequency interference causes cell edge spectrum efficiency deteriorating
High spectral efficiency requirement needs mono-frequency network deployment
Interference
randomization
Interferencecoordination
based on SFR/FFR
Interferencecancellation
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Interference coordination & management
Comparison
Though does not decrease interferences power but whitens it.
SINR improvement is limited. Sole utilization of randomization can
not satisfy the SINR requirement of LTE.
Easy to implement.
Interference
randomization
Interference
cancellation
High complexity
Strict resource allocation requirement
Strict inter cell synchronization requirement
Interference
coordination
based on FFR
SFR/FFR allocates adjacent cells cell edge users orthogonal frequency, so inter
cell interference is decreased. Residual interference is decreased by
pro-active mode and passive mode interference coordination based on
indicators exchanging between different adjacent eNodeBs.
Balance of complexity and performance.
The last one for
consideration
Combine
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ICIC types for LTE
Based on frequency adjustment
Type-1: Static ICIC;
Type-2: Semi-static ICIC;
Type-3: Dynamic ICIC.
Modes for non-static ICIC:
Mode-1: Pro-active Mode;
Mode-2: Reactive Mode.
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High Complexity, Not easy Implementation,
Middle Overhead, Middle CAPEX and Low
OPEX, Suitable to load of 35%~70%.
Performance improved more. Fit to slowly
varying load.
1 Type 1 Static ICIC
2 Type 2 Semi-Static ICIC
3 Type 3 Dynamic ICIC
Low Complexity, Easy Implementation,
Low Overhead, Low CAPEX and High OPEX,
Fit to load of 35%~50%, Performance lightly
improved. Not fit to varying load.
High Complexity, Hard Implementation, High
overhead, High CAPEX and Low OPEX, Fit to
load of 35%~70%, Performance improvedmost. Fit to varying load.
Comparison of Different ICIC Types in LTE
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Contents
ICIC Introduction
ICIC theory and scheme
ICIC Performance
ICIC Application
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Universal Frequency Reuse (Reuse factor = 1)
All cells and sectorsuse the same
frequency which is
showed by the same
grey color. ICI is generated
Sector 2
Sector 1Sector 3
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Different-Frequency Reuse (Reuse factor = 3)
neighbor sectors havedifferent frequency
which is showed by the
different colors (red
green and blue). ICI is decreased
Sector 2
Sector 1
Inner
Sector 3
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Fractional Frequency Reuse (1
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Soft Frequency Reuse (1
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ICIC Modes for LTE
Modes for Static ICIC Type-1: FFR;
Type-2: SFR/SFR2.
Modes for Semi-Static ICIC
Type-1: Pro-active SFR/SFR2;
Type-2: Reactive SFR/SFR2.
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Static ICIC in LTE-introduction
Static ICIC No coordination between different eNodeBs.
Based on FFR/SFR/SFR2, i.e. , Try to allocate
orthogonal cell edge resources to neighbor cells. The
frequency reuse factor target for cell edge is 3, and thefrequency reuse factor target for cell center is 1. i.e.,
both the cell edge efficiency and system efficiency is
under consideration in design.
Different resources allocation is allowed and powercontrol is allowed for interference mitigation. Such as
FFR, SFR, SFR2.
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Static ICIC in LTE-Frequency Allocation
Scheme
Different Frequency Resource Allocation schemes FFR (Fractional Frequency Reuse)
In FFR, one frequency band in a sector is defined as
use or not use, The Power for different frequency band
is the same. The system equivalent frequency reusefactor in the interval of [1, N].
System bandwidth divided into N orthogonal parts. Each sector
edge use one part orthogonal to neighbor sectors. Each sector
center use the same part with neighbor sectors.
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Static ICIC in LTE-Frequency Allocation
Scheme
SFR (Soft Frequency Reuse) In SFR, one frequency band in a sector is not defined as use or not
use, but defined as how much power allocated the frequency wasused in a cell. The system equivalent frequency reuse factor in theinterval of [1, N].
Main principle for SFR:
System bandwidth divided into N orthogonal parts. For each sector,select some parts as main carriers, others as auxiliary carriers, Thepower of main carriers are higher than auxiliary carriers.
Main carriers for different neighbor sectors are orthogonal.
Main carriers can be used for overall sector, but auxiliary carriers canonly be used in cell center.
By Adjusting the proportionality between main carrier power andauxiliary carrier power, SFR can adapt to the load distribution in celledge and cell center.
SFR2(Combination of SFR and FFR)
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Static ICIC in LTE-Frequency Allocation
Scheme
FFR System bandwidth divided into 4 bands, Cell Center
reuse 1,Cell Edge reuse 3
CA B D
B,C are not used. A is first allocated
to Cell edge user (CEU) . D is only
used for Cell center user (CCU).
Unallocated part of A can be used
for CCU together with D.
P Cell 1
F CA B D
A,C are not used. B is first allocated
to Cell edge user (CEU) . D is only
used for Cell center user (CCU).
Unallocated part of B can be used for
CCU together with D.
P Cell 2
F CA B D
A,B are not used. C is first allocated
to Cell edge user (CEU) . D is only
used for Cell center user (CCU).
Unallocated part of C can be used for
CCU together with D.
P Cell 3
F
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Static ICIC in LTE-Frequency Allocation
Scheme
SFR
System bandwidth divided into 3 bands, Cell Center
reuse (1 3), Cell Edge reuse 3.
CA B
D1=B+C
A is first allocated to CEU . D1 is only
used for CCU. Unallocated part
of A can be used for CCU together
with D1.
P Cell 1
F CA B
D2=A+C
B is first allocated to CEU . D2 is only
used for CCU. Unallocated part
of B can be used for CCU together
with D2.
P Cell 2
F CA B
D3=A+B
C is first allocated to CEU . D3 is only
used for CCU. Unallocated part
of C can be used for CCU together
with D3.
P Cell 3
F
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Static ICIC in LTE-Frequency Allocation
Scheme
SFR2 system bandwidth divided into 4 bands, Cell Center
reuse (1 3), Cell Edge reuse 3.
CA B D
A is first allocated to CEU. D1 is only
used for CCU. Unallocated part of A
can be used for CCU together with
D1. In D1, D is first allocated to CCU.
P Cell 1
F
D1=B+C+D
CA B D
P Cell 2
F
B is first allocated to CEU. D2 is only
used for CCU. Unallocated part of B
can be used for CCU together with
D2. In D2, D is first allocated to CCU.
D2=A+C+D
CA B D
P Cell 3
F
C is first allocated to CEU. D3 is only
used for CCU. Unallocated part of C
can be used for CCU together with
D3. In D3, D is first allocated to CCU.
D3=A+B+D
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Semi-static ICIC in LTE-introduction
Coordination between different eNodeBs; Frequencyallocation adapts to load distribution in Cell edge and cell
center. Reallocation is done on a time scale corresponding
to seconds. X2 signaling such as HII, OI and RNTP are
supported.
Based on FFR, i.e. , Try to allocate orthogonal cell edge
resources to neighbor cells. The frequency reuse factor
target for cell edge is 3, and the frequency reuse factor
target for cell center is 1. i.e., both the cell edge efficiency
and system efficiency is under consideration in design. Different resources allocation is allowed and power control
is allowed for interference mitigation. Such as FFR, SFR,
SFR2.
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Semi-static ICIC in LTE-X2 signaling
X2 signaling interacting Interacting signaling: HII and OI are used for uplink
semi-static ICIC. RNTP is used for downlink semi-staticICIC.
Interacting mode: HII and RNTP are pro-active mode.
OI is reactive mode. Interacting interval: Several tens of milliseconds for
semi-static ICIC.
Interacting granularity: Each RB has corresponding
indicators. Interacting flow chart: different respectively for different
indicators.
Interacting cells: cells in the neighbor cell list(NCL).
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HIIGenerate HII for
CEU PRB
S
C
H
E
D
U
L
ER
System load
statistics
NeighborcellsHII
Classify CEU
and CCU
Allocate time-frequencyand power resources to
CCU and CEU
Decide CCU and
CEU Band allocation
UE s Tx powerand SINR statistics
UE s RSRPreport
If high
load, power
Of HII
indecated
PRBs
be lowered
Service Type
Power
Control
Decide UE s powervariable
IoT test on
Each PRB
If lightly load,
HII indicated
PRBs will not
be allocated toCEU and high
SINR CCU
Semi-static ICIC in LTE-X2 signaling-HII X2 signaling interacting flow chart:
HII for Up link
If one PRB is allocated to CEU by scheduler, the HII indicator for the PRB isgenerated as 1,
otherwise 0. The HII bitmap is generated for each target cell based on cellrelated CEUs HII
Indicator statistics in report interval. Upon receiving HII bitmap, in lightly loadthe HII indicated
PRBs will not be allocated to CEU and high SINR CCU; in high load the power
of HII indicated PRBs will be lowered.
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Semi-static ICIC in LTE-X2 signaling-OI X2 signaling interacting flow chart:
OI for Upl in k
The OI indicator for each PRB is generated in the IOT test. OI have four values:high, medium,
low, and null. The bitmap is generated based on RNTP indicators statistics inreport interval
and sent to all neighbor cells in NCL by X2 interface. If OI from stronginterfering cells received,
the Tx power of the OI indicated PRB should be Adjusted based on OI, UEsSINR and Tx
Power statistics.
OIGenerate OI for
CEU PRB
SC
H
E
D
U
L
E
R
System load
statistics
Neighbor cellsOI
Classify CEUand CCU
Allocate time-frequency
and power resources to
CCU and CEU
Decide CCU and
CEU Band allocation
UE s Tx powerand SINR statistics
UE
s RSRPreport
Service Type
Power
Control
Decide UE s powervariable in inner loop
Power control
IoT test on
Each PRB
Decide uplink
power
variable in
outer loop
Power control
for overall cell
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Semi-static ICIC in LTE-X2 signaling-
Downlink-RNTP X2 signaling interacting flow chart:
RNTP for Down l ink
If one PRB is allocated by scheduler, the RNTP indicator for the PRB is generated by
eNodeB
as follows. The RNTP bitmap is generated based on RNTP indicators statistics in report
interval and sent to all neighbor cells in NCL. Upon receiving RNTP bitmap, the PRB with
RNTP=1 will not be allocated to CEU whose CQI is too small.
S
C
H
E
D
UL
E
R
System load
statistics
Generate RNTP for
each PRB
Neighbor
cells
RNTP
Classify CEU and
CCU
Allocate time-frequency and power
resources to CCU
and CEU
Decide CCU and
CEU Band allocation
UEs CQI reportand power
statistics for UEs
PRB
UEs RSRPreport
Service Type
( )
max_
( )
max_
( )if
( ) 0;
no promise about the upper
( )limit of is made
( ) 1;
A PRBthresholdp
nom
PRB
A PRBp
nom
PRB
E nif RNTP
E
RNTP n
if
E nE
RNTP n
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Contents
ICIC Introduction ICIC theory and scheme
ICIC Performance
ICIC Application
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ICIC Simulation Results-Semi-Static Uplink
Differentsystem load
simulation.
Frequency reuse scheme SE ESE RB Usage
bps/Hz/cell bps/Hz/user %
Load=90%
FR=1 1.027 0.0281 93.87
SFR 1.060 0.0217 88.32
HII 1.019 0.0282 93.41
Load=80%
FR=1 0.934 0.0403 82.18
Static SFR 0.969 0.0439 76.26Semi-static SFR+HII 0.942 0.0419 81.66
Load=70%
FR=1 0.873 0.058 72.55
Static SFR 0.914 0.0594 67.74
Semi-static SFR+HII 0.884 0.0642 72.34
Load=50%
FR=1 0.735 0.0647 54.22Static SFR 0.780 0.0785 50.79
Semi-static SFR+HII 0.761 0.0798 52.96
Load=35%
FR=1 0.612 0.1006 37.75
SFR 0.628 0.075 34.33
HII 0.627 0.0905 37.79
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ICIC Simulation Results-Semi-Static Uplink
ESE figure for Different system load simulation.ESE
0
0.02
0.04
0.06
0.08
0.1
0.12
99% 90% 80% 70% 50% 35%
Load
bps/Hz
FR=1
SFR
HII
OI
HII+OI
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ICIC Simulation Results-Semi-Static Uplink
SE figure for Different system load simulation.SE
0.000
0.200
0.400
0.600
0.800
1.000
1.200
99% 90% 80% 70% 50% 35%
Load
bps/Hz
FR=1
SFR
HII
OI
HII+OI
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ICIC Simulation Results-Semi-Static Uplink
Some comments
HII is introduced into uplink semi-static ICIC compared with
uplink static ICIC.
Compared with FR=1, semi-static ICIC using HII can improve
cell edge spectrum efficiency.
Compared with static SFR, under high load and low load
scenarios semi-static ICIC is better; under medium load,
semi-static ICIC has near performance.
Compared with static SFR, semi-static ICIC is more capable of
tracking system load variation.
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ICIC Simulation Results-Semi-Static Downlink
70
load
k
0.15
45loadk0.10
FreqUse
Type
CEU
RatioOC RB PwRatio SE ESE ALLRBratio Avg.Bler
bps/Hz/cell bps/Hz/user bps/Hz/user %
FR=1 0.5 12 1 1.7469 0.0329 72.7162 5.6788
SFR 0.4 16 2 1.5803 0.0380 69.6275 4.3261
FreqUse
Type
CEU
RatioOC RB PwRatio SE ESE ALLRBratio Avg.Bler
bps/Hz/cell bps/Hz/user bps/Hz/user %
FR=1 0.4 16 1 1.1984 0.0206 45.8041 4.0891SFR 0.4 16 2 1.1011 0.0235 43.9899 2.6279
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ICIC Simulation Results-Semi-Static Downlink
Some comments
For downlink ICIC, individual frequency band allocation
will not have obvious advantage to interference mitigation.
Interference mitigation depend on the power allocationfor CCU and CEU. For CEU, signal transmit power is
higher. So performance increasing of CEU must be at the
cost of CCU performance decreasing. From the statistics,
in order to improve ESE, SE is degraded. It can be seen
that, SFR can improve ESE at the cost of SE.
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Contents
ICIC Introduction ICIC theory and scheme
ICIC Performance
ICIC Application
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ICIC Application Scenario
Rural ICIC Be suitable;
The service load change
very slowly;
Rural Scenarios Pls. See
figures below.
Sub-Urban ICIC Be suitable;
Important future living place.
Sub-Urban Scenarios Pls.
See figures below.
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ICIC Application Scenario
Urban static ICIC not suitable;
density people and complicated radio propagation environment.
Service load change more quickly because of subscribers moving;
Urban Scenarios Pls. See figures below.
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ICIC Roadmap
Stage 1-2009Q4 Stage 2-Planning
Dynamic ICICStatic ICICSemi-static ICIC
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