1、fdd-lte radio icic-34

FDD-LTE Radio ICIC

ZTE University

Contents

ICIC Introduction

ICIC theory and scheme

ICIC Performance

ICIC Application

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 achieve improved coverage

area compared to universal frequency

reuse( frequency reuse factor is equal to one)

network deployment and keep proper system

spectrum efficiency simultaneously.

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

Interference

coordination

based on SFR/FFR

Interference

cancellation

Interference coordination & management –

Comparison

Though does not decrease interference’s 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

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.

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 improved

most. Fit to varying load.

Comparison of Different ICIC Types in LTE

Contents

ICIC Introduction


ICIC Performance

ICIC Application

Universal Frequency Reuse (Reuse factor = 1)

Frequency reuse factor 1

All cells and sectors use

the same frequency

which is showed by the

same grey color.

ICI is generated

Sector 2

Sector 1Sector 3

Different-Frequency Reuse (Reuse factor = 3)

Frequency reuse factor 3

neighbor sectors have

different frequency

which is showed by the

different colors (red

green and blue).

ICI is decreased

Sector 2

Sector 1

Inner

Sector 3

Soft Frequency Reuse

Fractional Frequency Reuse (1<Reuse factor<3)

1< Frequency reuse factor <3

Cell edge region in neighbor cells

have different frequency which is

showed by the different colors

(red, green and blue). But cell

center region in neighbor cells

have the same frequency which is

showed in the grey color.

ICI is somehow decreased

compared with mono-frequency

reuse.

In SFR, total band=A+B+C, D=total

band – cell edge band. In FFR,

total band=A+B+C+D.

Sector 2

Sector 1

Inner

Sector 3

C A

B D

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.

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 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.

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 reuse factor 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.

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 was used in a cell. The system equivalent frequency reuse factor in the interval of [1, N].

Main principle for SFR:

1. System bandwidth divided into N orthogonal parts. For each sector, select some parts as main carriers, others as auxiliary carriers, The power of main carriers are higher than auxiliary carriers ;

2. Main carriers for different neighbor sectors are orthogonal;

3. Main carriers can be used for overall sector, but auxiliary carriers can only be used in cell center;

4. By Adjusting the proportionality between main carrier power and auxiliary carrier power, SFR can adapt to the load distribution in cell edge and cell center.

SFR2(Combination of SFR and FFR)


Scheme Different Frequency Resource Allocation schemes

FFR

system

bandwidth

divided into 4

bands, Cell

Center reuse

1,Cell Edge

reuse 3

SFR

system

bandwidth

divided into 3

bands, Cell

Center reuse

(1 3), 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



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



Unallocated part of C can be used for

CCU together with D.

P Cell 3

F

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


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


of C can be used for CCU together

with D3.

P Cell 3

F


Scheme

Different Frequency Resource Allocation schemes

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 CA B D

P Cell 2

F CA B D

P Cell 3

F

D1=B+C+D

B is first allocated to CEU. D2 is only

used for CCU. Unallocated part of B



D2=A+C+D

C is first allocated to CEU. D3 is only

used for CCU. Unallocated part of C



D3=A+B+D

Semi-static ICIC in LTE-introduction

Semi-Static

Coordination between different eNodeBs; Frequency allocation 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.

Semi-static ICIC in LTE-X2 signaling

X2 signaling interacting

Introduction

Interacting signaling: HII and OI are used for uplink semi-static ICIC.

RNTP is used for downlink semi-static ICIC.

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).

HIIGenerate HII for

CEU PRB

S

C

H

E

D

U

L

E

R

System load

statistics

Neighbor

cells’HII

Classify CEU

and CCU

Allocate time-frequency

and power resources to

CCU and CEU

Decide CCU and

CEU Band allocation

UE’s Tx power

and SINR statistics

UE’s RSRP

report

If high

load, power

Of HII

indecated

PRBs

be lowered

Service Type

Power

Control

Decide UE’s power

variable

IoT test on

Each PRB

If lightly load,

HII indicated

PRBs will not

be allocated to

CEU and high

SINR CCU

Semi-static ICIC in LTE-X2 signaling-HII X2 signaling interacting flow chart:

HII for Uplink

If one PRB is allocated to CEU by scheduler, the HII indicator for the PRB is generated as 1,

otherwise 0. The HII bitmap is generated for each target cell based on cell related CEU’s HII

Indicator statistics in report interval. Upon receiving HII bitmap, in lightly load the 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.

Semi-static ICIC in LTE-X2 signaling-OI X2 signaling interacting flow chart:

OI for Uplink

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 in report interval

and sent to all neighbor cells in NCL by X2 interface. If OI from strong interfering cells received,

the Tx power of the OI indicated PRB should be Adjusted based on OI, UE’s SINR and Tx

Power statistics.

OIGenerate OI for

CEU PRB

S

C

H

E

D

U

L

E

R

System load

statistics

Neighbor cells’OI

Classify CEU

and CCU

Allocate time-frequency

and power resources to

CCU and CEU

Decide CCU and

CEU Band allocation

UE’s Tx power

and SINR statistics

UE’s RSRP

report

Service Type

Power

Control

Decide UE’s power

variable in inner loop

Power control

IoT test on

Each PRB

Decide uplink

power

variable in

outer loop

Power control

for overall cell

Semi-static ICIC in LTE-X2 signaling-

Downlink-RNTP X2 signaling interacting flow chart:

RNTP for Downlink

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

U

L

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

UE’s CQI report

and power

statistics for UE’s

PRB

UE’s RSRP

report

Service Type

( )

max_

( )

max_

( ) if

( ) 0;

no promise about the upper

( )limit of is made

( ) 1;

A PRBthresholdp

nom

PRB

A PRB

p

nom

PRB

E nif RNTP

E

RNTP n

if

E n

E

RNTP n

Contents

ICIC Introduction


ICIC Performance

ICIC Application

ICIC Simulation Results-Semi-Static Uplink

Different system 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 76.26

Semi-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 54.22

Static 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


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


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


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.

ICIC Simulation Results-Semi-Static Downlink

70％ load（k＝0.15）

FreqUse Type

CEU Ratio

OC 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

45％load（k＝0.10）

FreqUse Type

CEU Ratio

OC 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 4.0891 SFR 0.4 16 2 1.1011 0.0235 43.9899 2.6279

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 allocation

for 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.

Contents

ICIC Introduction


ICIC Performance

ICIC Application

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.

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.

ICIC Roadmap

Stage 1-2009Q4 Stage 2-Planning

Dynamic ICICStatic ICIC

Semi-static ICIC

1、fdd-lte radio icic-34

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