Aviat Networks LTE Backhaul Capacity
Transcript of Aviat Networks LTE Backhaul Capacity
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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
LTE Cell: Single User Throughput Estimates
• 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)
Data Rate Down/Up [Mbps] vs. Distance from Cell Center
Channel Bandwidth Close Medium Far
5Mhz 17 / 5.6 11 / 3.7 5.6 / 1.8
(FDD typical) 10MHz 43 / 14.4 28 / 9.5 14 / 4.8
20MHz 85 / 28 56 / 18 28 / 9.5
High LTE data speeds require exclusive use of radio cell!
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Estimating LTE Cell Backhaul Capacity
• 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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Cell backhaul capacity [Mbps] vs. deployment areaChannel
BandwidthDense Urban
(close range throughput)Sub-urban
(medium range throughput)Rural
(medium range throughput)
5Mhz 20 (OBF 3) 13 (OBF 3) 8 (OBF 5)
(FDD typical) 10MHz 50 (OBF 3) 33 (OBF 3) 20 (OBF 5)
20MHz 100 (OBF 3) 65 (OBF 3) 40 (OBF5)
LTE backhaul realistically 10’s, not 100’s of Mbps
Backhaul Capacity Trend: 10MHz LTE ChannelCapacity[Mbps]
100
75
50
4x4 MIMO, 64QAM
2x2 MIMO, 64QAM
No MIMO, 64QAM
LTE theoretical max. radiothroughput (Layer 1)
LTE launch Service uptake,New data plans
New 2x2 hand-sets, more sites
4x4 upgrade,Service uptake
30
40
60
0
LTE single sector backhaul capacity requirement
Time
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Backhaul Topology Comparison for LTE
LTE Backhaul Topology
FeatureDaisy chain Hub &
SpokeTree/Tiered
Mesh/Ring
Capacity distribution
Achieve required network availability
Provide LTE cell-to-cell connectivity (X2)
Network cost factor
Future proof factor
Mesh or Ring topology best for LTE backhaul network
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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
To/fromcore network
50Mbps
50Mbps70Mbps
50Mbps70Mbps
100Mbps
150Mbps
Additional ring sites only add incremental capacity!
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The LTE Hype Cycle
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LTE
YOU ARE HERE!
Gartner Hype Cycle, 1995
3G
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/sfor 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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S T U A RT L I T T L E , D I R E C TO R O F M A R K E T I N G , AV I AT N E T W O R K S
HOW LICENSED MICROWAVE MEETS THE BACKHAUL CAPACITY NEEDS OF LTE
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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LTE Cell-Site Capacity
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Time
Capacity
Zone of Capacity Growth Maximum Cell-site Capacity
Maximum Cell-site Capacity (100-200Mbit/s)
Maximum Microwave Capacity Room for future capacity growth
You can’t outstrip MW capacity to a cell-site - physics won’t allow it!
Cell-site Capacity Curve
1 Gbit/s
Why pay for capacity you may never need?
• The total cost of building or leasing fiber to the cell-site 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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The 3 Most Important Backhaul Decision Factors
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Microwave is cheaper than fiber (in nearly all cases)
Microwave far exceeds LTE cell
site capacity demands
Each link needs to be evaluated to understand microwave and fiber costs and capacities…
OR RISK
Microwave connected cell sites often have greater uptime than
fiber sites
CAPACITY COST RELIABILITY
Microwave Capacity Expansion Options
• Native Ethernet transport• Adaptive Modulation• Adaptive Coding• Ethernet Frame suppression and compression
• Capacity-doubling through co-channel operation with XPIC
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Microwave techniques for high capacity
300Mbit/s
350Mbit/s
400Mbit/s
450Mbit/s
500Mbit/s
550Mbit/s
600Mbit/s
311 Mbit/s
360 Mbit/s
380 Mbit/s
470 Mbit/s
550 Mbit/s
+16%
+6%
+24%
+17%
2xOC3/STM1
Native Ethernet Throughput
Add Light Coding
Add IFG & Preamble Suppression
Add MAC Header Compression
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*Throughput figures are based upon maximum modulation in a 56/80 MHz channel for 64 byte frame sizes. Capacity will be less for smaller channels and/or larger frame sizes.
Co-Channel link capacity doubling
300Mbit/s
400Mbit/s
500Mbit/s
600Mbit/s
700Mbit/s
800Mbit/s
900Mbit/s
1100 Mbit/s
1000Mbit/s
1100Mbit/s
1200Mbit/s
+100%
Add Co-Channel Operation with XPIC
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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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Don’t let fiber break the bank!
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• 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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