Presented at the Packet Microwave Forum 2011.

1. www.cbnl.com
Next generation thinking
Data Centric Backhaul
John Naylon
October 2011

2. Contents
• The quality of experience problem space
• Architectures compared
• Applicability to next generation networks
• Conclusions
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3. The Problem Space: Data is Dominant
• Mobile traffic is now dominated by data
− Data overtook voice in 2009
− Data volume is growing exponentially
• It costs the same to backhaul a byte of
voice as a byte of data
− But user price for a data byte is much lower
• Efficient data backhaul is a critical
issue for mobile operators today
Mobile Data Growth, Actual and Forecast
Sources: Cisco VNI
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4. Smartphones, Tablets and Cloud Apps are the Norm
• 78% of tablets shipped will have a 3G/4G
modem in 2015
• By 2015, 65% of e-readers worldwide will
ship with an embedded 3G/4G modem.
• Approximately 16 million portable and
computing devices shipped with 3G/4G
cellular connectivity in 2010
• 70% of the companies currently using cloud-
based services plan to move additional tools
to the cloud in the next 12 months
• 63% of cloud users say being on the cloud
has decreased performance issues
• SandHill survey of 500 IT decision-makers;
50% say their primary reason for adopting
cloud applications is business agility.
Source: Gartner, In-Stat 4
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3rd party logo’s and trademarks acknowledged

5. End of the PC?
iPhone was an awakening ...all it needed was a bigger screen
• By the time we got to the iPhone 3Gs, • ...And the iPad was
people realised they were spending born. As more people
more time on their phones doing more buy iPhones (18m per
than they ever dreamt! quarter), more people
will buy iPads!
The PC replaced the typewriter Cloud OS and apps are next
• It took PC’s 15 years to replace • Chrome OS has almost no identifiable
typewriters... now we use several need for anything but minimal amounts of
local storage. Cloud computing demands
computers each day, some are high performance networks to deliver a
stationary, others are mobile, most good experience
are embedded. Networks will enable it
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6. The Problem Space: Wireless dominant in the last mile
• Need to connect mobile base stations
(node Bs) to core network 100%
− Could use copper, fibre or microwave radio
− Microwave is the dominant choice
− Circa 500k microwave backhaul connections 75%
per year
50%
25%
0%
08 09 10 11 12 13 14 15
Year
Microwave Fibre Copper
Worldwide Installed Mobile Backhaul Connections
Source: Infonetics Research
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7. The Problem Space: Shape of Data
• Data is “bursty”, uncorrelated, asymmetric
− This characteristic is driven by user and application behaviour
− Burstiness still present when traffic is aggregated within a node B
Handset traffic (one iPhone 4)
Peak: 11.44 Mbps
Mean: 0.14 Mbps
Ratio: 79.20 Mbps
Handset traffic (10 Devices)
Peak: 12.07 Mbps
Mean: 1.44 Mbps
Ratio: 8.37 Mbps
Node B backhaul traffic
Peak: 23.31 Mbps
Mean: 5.54 Mbps
Ratio: 4.20 Mbps
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8. The Problem Space: Peak to Mean Ratio
• RAN air interfaces are becoming
more sophisticated, with larger *
carriers
− Potential peak upload and download
speeds increase
• Peak-to-mean ratio of backhaul
traffic averages 3.9:1 across a broad
range of peak speeds
− We must provision at least the
peak, and the mean utilisation of the link
is at most equal to the mean offered
load
− Therefore mean utilisation of point-to-
point links to node Bs limited to ~25%
− To improve on this utilisation, we must
use PMP to take advantage of other
properties of the traffic (see section 2) * HSPA+ 21.6 tri-cellular nodeBs
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9. Challenge: Deliver a superior customer experience
• Changing customer behaviours and
devices demand high peak download
speeds, low latency
• Cloud-based applications and storage
increases pressure on network
performance
• Backhaul solutions need to be high
capacity and low latency to retain
customers and low opex to deliver
business case
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10. Contents
• The quality of experience problem space
• Architectures compared
• Applicability to next generation networks
• Conclusions
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11. Architecture 1: Point-to-Point Microwave Radio, Star Topology
• The most common microwave topology in use today
− For N links, 2N radios
− Dedicated RF channel for each node B served
− Circuit-switched architecture is well-suited to constant bit rate traffic
− Conventional and E-Band frequencies
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12. Architecture 2: Point-to-Multipoint Microwave Radio
• The fastest growing microwave topology today
− For N links, N+1 radios
− Shared RF channel amongst all node Bs served
− Packet-switched architecture is well-suited to variable bit rate (bursty) traffic
− Well-suited to dense environments
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13. Comparison: Installation and Maintenance
Point-to-Point Point-to-Multipoint
2 ODUs per link 1 hub ODU plus 1 RT per link
2 truck rolls per link added 1 truck roll per link added
2 antenna rentals per link 1 hub site rental plus 1 per link
2 units power per link 1 unit power per hub plus 1 per link
• 16 ODUs/truck rolls/antennas • 9 ODUs/truck rolls/antennas
• 16 units of power consumption • 9 units of power consumption
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14. Comparative Case Study
• We examine measured backhaul profiles from a group of eight node Bs
− Live network, large middle-eastern operator, heavy data usage
− HSPA+ 21.6Mb/s tri-cellular node Bs
− Theoretical maximum throughput 64.8Mbp/s per site
• Consider the amount of spectrum needed for each of the two topologies
− Use the bare minimum of spectrum to carry exact data profile (no ‘headroom’)
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15. Comparison: Spectrum Required
Point-to-Point Point-to-Multipoint
Cumulative Peak: 123.2 Mbps Cumulative Mean: 39.7 Mbps Cumulative Peak: 77.9 Mbps Cumulative Mean: 39.7 Mbps
• Spectrum required = 15.4 MHz • Spectrum required = 9.7 MHz
* 256-QAM assumed in both cases
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16. Comparison: Channel Utilisation
Point-to-Point Point-to-Multipoint
Cumulative Peak: 123.2 Mbps Cumulative Mean: 39.7 Mbps Cumulative Peak: 77.9 Mbps Cumulative Mean: 39.7 Mbps
• Efficiency = 32.2% • Efficiency = 51.0%
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17. Contents
• The quality of experience problem space
• Architectures compared
• Applicability to next generation networks
• Conclusions
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18. Backhaul for LTE
•
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19. LTE deployments will be macro and small cells
• Demand for mobile traffic is increasing on average by about 100% per annum
− So in the next 5 years we expect growth of about 20—40
• Capacity is provided by network operators using the following parameters:
Capacity = Spectrum Mean Spectral Efficiency Site Density
• In the next 5 years:
− Spectrum will almost double = 2
− 3G and 4G technology will roughly double mean spectral efficiency = 2
− This gives a capacity gain per site of = 4
− The only tool left in the box is site density and therefore I need = 5—10
higher site density to give the necessary result of network capacity = 20—40
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20. PMP Advantages Increase with Site Density: Efficiency
• PMP advantages increase as the RAN gets denser
− More sources in a PMP sector results in more statistical multiplexing gain
− Measured results from 922 node Bs backhauled across VectaStar PMP
− Live network, HSPA+ 21Mpbs, very heavy data usage
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21. Comparison: Installation and Maintenance
Point-to-Point Point-to-Multipoint
2 ODUs per link 1 hub ODU plus 1 RT per link
2 truck rolls per link added 1 truck roll per link added
2 antenna rentals per link 1 hub site rental plus 1 per link
2 units power per link 1 unit power per hub plus 1 per link
• 16 ODUs/truck rolls/antennas • 9 ODUs/truck rolls/antennas
• 16 units of power consumption • 9 units of power consumption
At 8 Links = PMP Saving of 7 ‘units’
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22. PMP Advantages Increase with Site Density: CAPEX and OPEX
Point-to-Point Point-to-Multipoint
2 ODUs per link 3 hub ODUs plus 1 RT per link
2 truck rolls per link added 1 truck roll per link added
2 antenna rentals per link 3 hub site rental plus 1 per link
2 units power per link 3 unit power per hub plus 1 per link
• 160 ODUs/truck rolls/antennas • 83 ODUs/truck rolls/antennas
• 160 units of power consumption • 83 units of power consumption
At 80 Links = PMP Saving of 77 ‘units’
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23. Another Dimension: LOS or NLOS
Requirement: Capacity Coverage
Aggregating 10 cells to a PoP Cells in cluttered locations
requires 10 mean cell capacity Uncertain LOS to PoPs
Implications:
High capacity and NLOS capability are
mutually exclusive requirements
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24. Contents
• The quality of experience problem space
• Architectures compared
• Applicability to next generation networks
• Conclusions
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25. Summary
• Data is bursty, uncorrelated, asymmetric and growing like crazy
− Not easy to backhaul efficiently
• Point-to-point microwave is fundamentally a circuit switched architecture
− Packet data does not map onto circuits well (!)
− Utilisation of the average point-to-point link backhauling mobile data is ~25%
• Point-to-multipoint microwave provides true packet switching and:
− The same user experience
− More efficient utilisation of spectrum
− Less equipment to install and maintain
• Point-to-multipoint advantages are increasing with current RAN trends
− Higher peak speeds imply better statistical multiplexing gain
− Capex and Opex advantages scale with network density
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