14. LTE BACKHAUL REQUIREMENTS
A REALITY CHECK
P E T E R C R O Y, S E N I O R N E T W O R K A R C H I T E C T, AV I AT N E T W O R K S
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15. LTE Cell: Single User Throughput Estimates
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• IP packet throughput rates vary with RF channel bandwidth and user distance
from cell center
• Majority of handsets in a cell/sector are located within medium & far distance
from the cell center (>90% of cell coverage area)
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16. Estimating LTE Cell Backhaul Capacity
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• Typical macro cell tower hosts 3 LTE radio sectors
• Site backhaul capacity with overbooking factor (OBF) between 3 and 5
• Capacity includes 15% dynamic range margin for QoS
• Figures are already LTE high-end estimates, higher capacities through
reducing overbooking factor to 1 from 3
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19. Backhaul Capacity Example: Ring Architecture
• Six cell backhaul in dense urban area @50Mbps
• Multiple site packet capacity not simply sum of cell capacities
• Network recovers from any single link failure
70Mbps
50Mbps
100Mbps
150Mbps To/from
core network
50Mbps
50Mbps
70Mbps
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21. LTE Capacity Conclusions
• LTE backhaul capacity needs are regularly over-stated
• Capacity is fixed per site and only determined by base
station technology
• The backhaul limit for a site will likely be ~150 Mbit/s
for a 10MHz LTE radio channel
• Only way to add more network capacity:
- Add more cell sites, upgrade to MIMO or increase the LTE channel
bandwidth
• Ring/Mesh topologies are best suited to cope with the
high capacity requirements
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22. HOW LICENSED MICROWAVE
MEETS THE BACKHAUL CAPACITY
NEEDS OF LTE
S T U A R T L I T T L E , D I R E C T O R O F M A R K E T I N G , AV I AT N E T W O R K S
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23. Uncertainty can lead to bad backhaul choices
• Backhaul discussion often in
terms of hundreds of megabits or
even gigabits of capacity
• Just one in four mobile operators
have said that they understood
the requirements for LTE
backhaul
• This uncertainty could drive over-
investment for backhaul capacity
that is not needed within the
foreseeable future
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25. Why pay for capacity you may never need?
• The total cost of building
or leasing fiber to the cellsite far exceeds that of a
typical microwave
connection
• Over-building capacity
with fiber will waste an
enormous amount of
network investments
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30. Getting even more wireless capacity
• Diverse path network topologies
(rings/mesh)
• Lightly licensed and license free
60-90 GHz Millimeter wave
bands
• Payload compression
• Higher order modulation
schemes >256QAM
• Multi-carrier operation
• Multiple-in/Multiple-out (MIMO)
techniques
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31. Don’t let fiber break the bank!
• Fiber is not the only
answer for operators
deploying HSPA+ & LTE
• Operators need to balance
realistic capacity
expectations with total cost
• Microwave transport meets
the foreseeable capacity
needs for mobile backhaul
for several years to come
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