1 Lte Eran6.0 Icic Feature Issue 1.00

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LTE eRAN6.0 ICIC Feature


Objectives

Upon completion of this course, you will be able to:

Describe basic concepts of ICIC, such as CCU,

CEU, etc.

Describe the ICIC A3/A6 event and related

parameters

Describe downlink and uplink ICIC procedures

Perform enable/disable ICIC functions

Describe the deployment strategy of ICIC

List the main parameters of ICIC

Page3


Contents1. Overview of ICIC

2. Cell Center User and Cell Edge User Identification

3. Edge Band Mode Assignment

4. ICIC Event A3/A6

5. Edge Band Adjustment

6. Downlink ICIC

7. Uplink ICIC

8. ICIC Deployment Strategy

Page4


Overview of ICIC

ICIC: Inter Cell Interference Coordination

Function:

Increase the cell edge user experience (throughput)

Increase the cell capacity

Page5

Huawei interference mitigation solutions

Interference Rejection Combining (IRC) :applied at the physical layer

Inter-Cell Interference Coordination (ICIC):applied at the MAC layer


Types of ICIC

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ICIC

Static ICIC

Dynamic ICIC

ICIC

DL ICIC

UL ICIC



2. Cell Center User and Cell Edge User

Identification


4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC


Page7


Cell Center User and Cell Edge User (CCU/CEU) identification To implement ICIC, the eNodeB must first identify

CCUs and CEUs correctly.

In the LTE system, UEs in the center of a cell usually

enjoy favorable radio conditions and do not require

ICIC. These UEs are called Cell Center Users (CCUs).

UEs at the edge of a cell, however, are affected by

interference from neighboring cells and therefore

require interference mitigation. These UEs are called

Cell Edge Users (CEUs).

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Cell Center User and Cell Edge User (CCU/CEU) identification (Cont.) When initially accessing a network, an UE is recognized as

a CCU

After a handover, the UE is recognized as a CEU

After a short period following the initial access or

handover, the eNodeB starts to use event A3 or A6 for ICIC

(referred to as ICIC event A3 or A6) to determine

whether the UEs are CEUs or CCUs.

If an ICIC A3/A6 report contains the measurement about

the serving cell only, the eNodeB treats the UE as a CCU

If an ICIC A3/A6 report contains the measurement result

about at least one neighboring cell, the eNodeB treats the

UE as a CEUPage9





4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC


Page10


Edge Band Mode Assignment

DL: ICIC operating band = system band of PDSCH

UL: ICIC operating band = system band - PUCCH

band (PUSCH)

The center band is mainly allocated to CCUs, and the

edge band is mainly allocated to CEUs.

Assignment of different edge bands to neighboring

cells must be planned, in Huawei eNodeB as

MODE1, MODE2 and MODE3.

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PRB

Edge band mode assignment

Edge band adjustment

CEU/CCU identificationICIC A3 Event

Power Control

MAC Scheduling

Power Control

MAC Scheduling

CEU CCU

Cell #N

PRB




Power Control

MAC Scheduling

Power Control

MAC Scheduling

CEU CCU

Cell #2

UE

PRB




Cell #1

Power Control

MAC Scheduling

Power Control

MAC Scheduling

CEU CCU

UL/DL grant

Edge Band Mode Assignment (Cont.)

Page12

PRB for edge band

PRB for center band



MODE1 MODE2 MODE3

Page13

MODE3

MODE2

MODE1

PDSCH/PUSCH



Page14



Page15

No ICIC ICIC

f (x)

Pow

e r

edge band

center band-

1.77dB66% of

RS power

0dB

-6dB25% of RS power

-3dB50% of RS power

f (x)

Pow

e r

0dB reference signal





4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC


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ICIC Event A3/A6 Based on RSRP Measurement

ICIC event A3 is used for reporting RSRP (Reference Signal

Received Power) measurement reports, based on which

DL ICIC and UL ICIC can determines the type of a UE in the

serving cell.

ICIC event A3 is reported in event-triggered periodical

reporting mode.

Entering condition:

Leaving condition:

ICIC event A6 is reported in event-triggered periodical

reporting mode.

Entering condition:

Leaving condition:

ICIC event A3 is reported only if either the entering

condition or leaving condition for ICIC event A3 is met for

a period of time

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Entering Condition for ICIC Event A3 Entering condition:

Page18

OffOcsOfsMsHysOcnOfnMn


Leaving Condition for ICIC Event A3 Leaving condition:

Page19

OffOcsOfsMsHysOcnOfnMn


More Parameters of ICIC Event A3

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MaxReportCellNum parameter: the maximum number of reported neighboring cells


Related MML of ICIC Event A3

MOD CELLDLICICMCPARA

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Related MML of ICIC Event A3 (Cont.) MOD CELLULICICMCPARA

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ICIC Event A3 Parameters Setting

A3Offset ↑=> CEU Number ↓

Hysteresis ↑=> probability of Ping-Pong ICIC A3↓

TimeToTrigger ↑ => probability of Ping-Pong ICIC

A3↓

ReportInterval ↑ => frequency of sending

measurement reports ↓ & UE info updated in time ↓

ReportAmount ↑ => UE power consumption ↑ &

CEU throughput improved by dynamic UL ICIC ↑

Note: TriggerQuantity only support RSRP now

Page23


Contents

1. Overview of ICIC



4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC


Page24


Edge Band Adjustment

If the static ICIC is used, edge bands sizes remain

unchanged and during the higher load, overlapping

PRBs may cause inter-cell interference.

Page25

X X X

Y Y Y Y

Collision

Neighboring cell

Serving cell

X: cell edge PRBs occupied in the neighboring cell

Y: cell edge PRBs occupied in the current cell

cell edge PRBs defined in static ICIC

cell center PRBs defined in static ICIC


Edge Band Adjustment (Cont.)

Only dynamic ICIC adjusts edge bands.

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X X X

Y Y Y

Neighboring cell

Serving cell

X: cell edge PRBs occupied in the neighboring cell

Y: cell edge PRBs occupied in the current cell

cell edge PRBs defined in static ICIC

cell center PRBs defined in static ICIC

Expanding

Shrinking

Y





4. ICIC Event A3/A6


6. Downlink ICIC2.1 Static DL ICIC

2.2 Dynamic DL ICIC

7. Uplink ICIC


Page27


Static DL ICIC

The major techniques used in Static DL ICIC are DL

band division activated by DlIcicSwitch to

DlIcicStaticSwitch_ON_ENUM value and UE type

determination based on previously explained

techniques.

Page28


Dynamic DL ICIC

If dynamic DL ICIC is enabled, the eNodeB allocates

an initial DL edge band to each cell based on the cell

bandwidth and edge band mode.

Then, the eNodeB periodically triggers adjustments

of the DL edge band.

Dynamic DL ICIC adjusts DL edge bands for cells

based on the interference and load information

exchanged between the cells.

Page29


Dynamic DL ICIC (Cont.)

Huawei-defined message includes: ID of the source cell

ID of the target cell

Coordination request indication

Load status of the source cell

Edge band status of the source cell

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Dynamic DL ICIC (Cont.)

If the edge band of the cell is adjusted, during the

dynamic ICIC procedure, this cell notifies

neighboring cells of this adjustment. Based on this

information neighboring cells either expand or

shrink their edge bands.

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DL ICIC Algorithm Switch MML

MOD ENODEBALGOSWITCH

Page32





4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC2.1 Static UL ICIC

2.2 Dynamic UL ICIC


Page33


Static UL ICIC

The major techniques used in Static UL ICIC are DL

band division activated by UlIcicFreqSwitch to

STATIC and UE type determination based on similar

techniques as with DL ICIC.

Page34


Dynamic UL ICIC

If dynamic UL ICIC is enabled, the eNodeB allocates

an initial UL edge band to each cell based on the cell

bandwidth and edge band mode.

The eNodeB triggers adjustments of the UL edge

band based on the edge band mode and High

Interference Indicator (HII) messages from

neighboring cells, containing:

ID of the source cell:

ID of the target cell:

Interference information

Page35


Dynamic UL ICIC (Cont.)

If the difference between the PRB number actually

used by CEUs and PRBs reserved for the edge band

is excessively large for a cell, the eNodeB triggers an

edge band adjustment. If the edge band of the cell is

adjusted, the cell transmits the updated HII

messages to its neighboring cells.

Neighboring cells then expand or shrink their edge

bands.

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UL ICIC Algorithm Switch MML

MOD ENODEBALGOSWITCH

Page37


Neighboring Cell List Management Neighboring cell lists for UL ICIC are classified into

two levels: UE level and cell level.

A UE-level neighboring cell list, which records the

information about neighboring cells, is created on the

basis of an RSRP measurement report sent from the

UE. The list is updated on the basis of the

subsequent RSRP measurement reports from the UE.

A cell-level neighboring cell list contains the

information about the interfering cells indicated in

the RSRP measurement reports from all the CEUs in a

cell. Page38


OI Message Processing

An OI message provides information that the

average interference caused to all RBs in a cell is

large. It also provides the level of interference

caused to each RB.

An OI message contains the following information:

ID of the source cell

Interference indication

Page39


Contents

1. Overview of ICIC



4. ICIC Event A3/A6


6. Downlink ICIC

7. Uplink ICIC


Page40


DL ICIC Deployment Strategy (1/3) DL ICIC is not recommended if any of the following

situations occurs:

Operators have high requirements for cell capacity but

low requirements for cell coverage.

The total load of cells is high but the edge load is low.

There are only a few UEs in cells, and therefore the

system throughput is low after ICIC is enabled because

of limited power or frequency band.

The system bandwidth is less than 3 MHz.

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DL ICIC Deployment Strategy (2/3) When the load of neighboring cells is approximately

balanced and the edge load is relatively low, static

DL ICIC can be used to allocate mutually orthogonal

edge bands to different cells for inter-cell

interference mitigation.

Dynamic DL ICIC can be used when the load of

neighboring cells is not evenly distributed. It adjusts

the edge bands of different cells dynamically and

thus mitigates inter-cell interference.

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DL ICIC Deployment Strategy (3/3) When the inter-cell interference is very high and

neither static DL ICIC nor dynamic DL ICIC can

achieve expected ICIC effects, the Reuse3 mode can

be used to allocate mutually orthogonal bands to

different cells for interference mitigation. In this

mode, however, the system capacity decreases

accordingly because only 1/3 of the ICIC operating

band is used in each cell.

Page43


UL ICIC Deployment Strategy (1/4) UL ICIC is not recommended if any of the following

situations occurs:

Operators have high requirements for cell capacity but

low requirements for cell coverage.

Cells are not interfered or UEs are insensitive to

interference, for example, most UEs are located in the

cell center.

The edge load of most cells is low, that is, CEUs have a

relatively low RB usage or interference level.

The system bandwidth is 1.4 MHz, and therefore only a

few RBs are available. In this situation, UL ICIC affects

scheduling.Page44


UL ICIC Deployment Strategy (2/4) Static UL ICIC is recommended if any of the following

situations occurs:

The load of neighboring cells is approximately

balanced.

Most cells have relatively low edge load, that is, the RB

usage of CEUs is not higher than one third of the

system RB usage.

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UL ICIC Deployment Strategy (3/4) Dynamic UL ICIC is recommended if the following

situations occur:

The load of neighboring cells is not balanced.

The RB usage of CEUs in cells with high edge load is

higher than one third of the system RB usage.

The RB usage of CEUs in cells with low edge load is

lower than one third of the system RB usage.

Page46


UL ICIC Deployment Strategy (4/4) Time-domain ICIC is applicable to intra-eNodeB cells,

which are time synchronized. If the frequency

resources cannot meet the requirements of CEUs in

intra-eNodeB neighboring cells with heavy edge

load, time-domain UL ICIC can be applied to improve

the effect of UL ICIC.

Page47


ICIC Related MML Review

MOD ENODEBALGOSWITCH, switching on/off ICIC

algorithm

MOD CELLDLICICMCPARA, setting DL ICIC A3

parameters

MOD CELLDLICIC, setting DL ICIC band mode

MOD CELLULICICMCPARA, setting UL ICIC A3

parameters

MOD CELLULICIC, setting UL ICIC band mode

Page48


Summary

The basic concepts of ICIC, such as CCU, CEU, Center

Band, etc.

The ICIC A3/A6 event (entering and leaving) and related

parameters

The downlink and uplink ICIC procedures

The deployment strategy of ICIC

MML to enable/disable ICIC functions

MML to setting ICIC bandmode

MML to seeting ICIC A3/A6 event

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Documents

1 Lte Eran6.0 Icic Feature Issue 1.00