This SON tutorial is part of the 3GPP Self-Organizing Networks series (#3GPPSONSeries). In this part we will look at what is meant by Inter-Cell Interference Coordination (ICIC) and how does the standard define the mechanism to help erase it. We will also look at some of the basic algorithms used for ICIC. All our #3G4G5G slides and videos are available at: Videos: https://www.youtube.com/3G4G5G Slides: https://www.slideshare.net/3G4GLtd 5G Page: https://www.3g4g.co.uk/5G/ Free Training Videos: https://www.3g4g.co.uk/Training/

1. Inter-Cell Interference Coordination
(ICIC)
@3g4gUK

2. Typical Cell Layout
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Non-Interference
Region
X2
Interference
Region

3. Typical Cell Layout with ICIC
©3G4G
Non-Interference
Region
Interference
Region
X2
✘
The goal of Inter-Cell Interference Coordination (ICIC) is to ensure there is no interference in overlapping areas between cells

4. Frequency Reuse Algorithms: HFR
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Hard Frequency Reuse
Power
Cell #1
Cell #2
Cell #3
Frequency
Frequency
Frequency
Power
Power

5. Frequency Reuse Algorithms: FFR
©3G4G
Hard Frequency Reuse Fractional Frequency Reuse (FFR)
Power
Cell #1
Cell #2
Cell #3
Frequency
Frequency
Frequency
Power
Power
Power Cell #1
FrequencyCell #2
Cell #3
Power
Power Frequency
FrequencyRegion with
full re-use
Region with hard
re-use

6. Frequency Reuse Algorithms: FFR
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Hard Frequency Reuse Fractional Frequency Reuse (FFR)
Reduced Tx power
Cell-center terminals, cell 1
Cell-edge terminals, cell 1
Cell-edge terminals, cell 2
Cell-edge terminals, cell 3
Power
Cell #1
Cell #2
Cell #3
Frequency
Frequency
Frequency
Power
Power
Power Cell #1
FrequencyCell #2
Cell #3
Power
Power Frequency
FrequencyRegion with
full re-use
Region with hard
re-use

7. Frequency Reuse Algorithms: SFR
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Hard Frequency Reuse Fractional Frequency Reuse (FFR) Soft Frequency Reuse (SFR)
Reduced Tx power
Cell-center terminals, cell 1
Cell-edge terminals, cell 1
Cell-edge terminals, cell 2
Cell-edge terminals, cell 3
Power
Cell #1
Cell #2
Cell #3
Frequency
Frequency
Frequency
Power
Power
Frequency
Frequency
Frequency
Power
Cell #1
Cell #2
Cell #3
Power
Power
Power Cell #1
FrequencyCell #2
Cell #3
Power
Power Frequency
FrequencyRegion with
full re-use
Region with hard
re-use

8. X2-AP Load Indication procedure
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X2-AP: Load Information
eNB 1 eNB 2

9. Load Information Contents
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❑ Uplink Interference management
▪ High Interference Indicator (HII)
– eNB sends 1 bit per resource
block (RB)
➢ Indicate Cell edge user on this resource
➢ Informed neighbours will avoid these RB
at cell edge
– Proactive process
▪ Overload Indicator (OI)
– eNB reports the level of
interference received
➢ Low, Medium, High
– Reactive process
❑ Downlink interference
management
▪ Relative Narrowband Transmit
Power (RNTP) Indicator
– eNB advertises Tx power per RB
– Proactive process
▪ Enables (dynamic) frequency
partitioning

10. Load Information Contents
©3G4G
❑ Uplink Interference management
▪ High Interference Indicator (HII)
– eNB sends 1 bit per resource
block (RB)
➢ Indicate Cell edge user on this resource
➢ Informed neighbours will avoid these RB
at cell edge
– Proactive process
▪ Overload Indicator (OI)
– eNB reports the level of
interference received
➢ Low, Medium, High
– Reactive process
❑ Downlink interference
management
▪ Relative Narrowband Transmit
Power (RNTP) Indicator
– eNB advertises Tx power per RB
– Proactive process
▪ Enables (dynamic) frequency
partitioning

11. Load Information Contents
©3G4G
❑ Uplink Interference management
▪ High Interference Indicator (HII)
– eNB sends 1 bit per resource
block (RB)
➢ Indicate Cell edge user on this resource
➢ Informed neighbours will avoid these RB
at cell edge
– Proactive process
▪ Overload Indicator (OI)
– eNB reports the level of
interference received
➢ Low, Medium, High
– Reactive process
❑ Downlink interference
management
▪ Relative Narrowband Transmit
Power (RNTP) Indicator
– eNB advertises Tx power per RB
– Proactive process
▪ Enables (dynamic) frequency
partitioning

12. Load Information Contents
©3G4G
❑ Downlink interference
management
▪ Relative Narrowband Transmit
Power (RNTP) Indicator
– eNB advertises Tx power per RB
– Proactive process
▪ Enables (dynamic) frequency
partitioning

13. Limitations of Rel-8/9 ICIC
©3G4G
• The frequency domain solution is more concerned with cell-edge
interference and homogeneous deployments
• The focus is more on data channels rather than control channels which
can be an issue for HetNet deployments
• PDCCH reception can be severely degraded at the cell edges and since
its spread over the entire bandwidth, RNTP can't be of much help.

14. Further Reading on ICIC
©3G4G
• Netmanias: Interference Coordination in LTE/LTE-A (1): Inter-Cell
Interference Coordination (ICIC) (link)
• Netmanias: Interference Coordination in LTE/LTE-A (2): eICIC (enhanced
ICIC) (link)
• Nomor Research: Heterogeneous LTE Networks and Inter-Cell
Interference Coordination (link)
• Wiley Online: Resource allocation strategies for full frequency reuse in
tri‐sectorized multi‐cell orthogonal frequency division multiple access
systems (link)
• The 3G4G Blog: eICIC: Enhanced inter-cell interference coordination in
3GPP Release-10 (link)
• Nomor Research: Inter-Cell Interference Coordination for LTE-A (link)

15. Thank You
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