A quick introduction to different kinds of backhaul used in mobile cellular communications from 3G, all the way to 5G.

1. Different Types of
Backhaul
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2. Simplified Network Architecture
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AS
CS NAS
Voice (PSTN)
Network
Data (IP)
Network
Device / UE
Radio
Access
Network
Core
Network
Air
Interface NAS = Non Access Stratum
AS = Access Stratum
UE = User Equipment
PS NAS
Backhaul
AS

3. Backhaul Types
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• Wired
• Optical (Fiber)
• (A)DSL
• Wireless
• Microwave (10 – 42 GHz)
• V Band / 60 GHz (57 – 64 GHz)
• E-band (71 – 76, 81 - 86 GHz)
• Satellite
• Wi-Fi Mesh
• LTE Backhaul
• TD-LTE Backhaul
• Self-backhauling
• Optical
• Laser

4. Wired Backhaul
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Optical Fiber Coaxial Cable Ethernet Cable

5. Wired Backhaul
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Virgin Media, UK advert singing praise of
Coaxial cable and DOCSIS 3 technology for
high speed broadband

6. ©3G4G

7. Wireless
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Line of Sight (LoS) Non Line of Sight (NLoS)

8. Wireless
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Line of Sight (LoS) Non Line of Sight (NLoS)
1. Penetration

9. Wireless
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Line of Sight (LoS) Non Line of Sight (NLoS)
1. Penetration
2. Reflection

10. Wireless
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Line of Sight (LoS) Non Line of Sight (NLoS)
1. Penetration
2. Reflection
3. Diffraction

11. Wireless
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Line of Sight (LoS) Non Line of Sight (NLoS) → Penetration
1. Penetration
2. Reflection
3. Diffraction
Near Line of Sight (nLoS) → Reflection, Diffraction

12. Wireless
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Point-to-Point (PTP) Point-to-MultiPoint (PMP)

13. Microwave Frequencies
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• Microwave (10 – 42 GHz)
• V Band / 60 GHz (57 – 64 GHz)
• E-band (71 – 76, 81 - 86 GHz)

14. 5G Problem
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Coverage Layer
Sub-1GHz
Capacity Layer
1GHz – 6GHz
High Throughput Layers
6GHz – 100GHz

15. 5G Problem
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16. Work on Spectrum above 90GHz
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17. Microwave Frequencies
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• Microwave (10 – 42 GHz)
• V Band / 60 GHz (57 – 64 GHz)
• E-band (71 – 76, 81 - 86 GHz)

18. V Band / 60 GHz (57 – 64 GHz)
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• Wide Bandwidth (7GHz)
• Low transmission distance - < 1km due to oxygen absorption at 60GHz
• Economy of scale – low cost
• Unlicensed – more sources of interference

19. Satellite Backhaul
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Picture Source: Vizocom

20. Backhaul Technologies Comparison
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Wireless Backhaul Spectrum Policy Recommendations & Analysis - GSMA, October 2014
Not
Necessarily
true

21. LTE Backhaul (In-Band)
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• Macrocell and Small Cell use the same frequency
f1 f1
f1
f1
MacrocellSmall Cell
Interference

22. LTE Backhaul (Out-of-Band)
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• Macrocell and Small Cell use different frequency
f1 f1
f2
f2
MacrocellSmall Cell

23. Wi-Fi Mesh & LTE Backhaul
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• Wi-Fi spectrum in 5GHz could be used to create Mesh links
f1
f2 f2
MacrocellSmall Cell 1
(Macrocell edge)
f2 f2
Small Cell 2
(No interference from
Macrocell)
f1f1
5GHz Mesh Link
f2 f2
Small Cell 3
(No interference from
Macrocell)
f1f1
f2 f2
Small Cell 4
(No interference from
Macrocell)
f1f1
f2 f2
Small Cell 5
(No interference from
Macrocell)
f1f1
5GHz Mesh Link
5GHz Mesh Link

24. TD-LTE Backhaul
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• Ericsson & ITRI (Taiwan) demoed this concept
• Small Cell in the train is transmitting on FDD
• The Small Cell is backhauled on TD-LTE

25. 5G Self-Backhauling
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• Multiple 5G Base Stations will be backhauled on the same frequency as the access
network
eMBB FWA
Small Cells for local coverage
Self-Backhauling

26. Optical – Laser Backhaul
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• High throughput rates
• Expensive
• LOS & PTP only
• Affected by fog and wind

27. Optical – Examples of Laser Backhaul
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AOptix reckons it’s got an alternative to fiber with a
hybrid laser and Millimeter spectrum setup.
Lightpointe HyBridge SX Single Beam - High speed full-
duplex Gigabit connectivity for highly secure, reliable
transmission up to a half mile/~750m.

28. Optical – Example of Laser Backhaul
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29. Thank You
To learn more, visit:
3G4G Website – http://www.3g4g.co.uk/
3G4G Blog – http://blog.3g4g.co.uk/
3G4G Small Cells Blog – http://smallcells.3g4g.co.uk/
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