In this presentation we look at the design requirements needed to backhaul small cell networks (covering capacity, coverage and cost) and how different backhaul options meet these needs. We look at: - How small cells will be deployed and what the implications are for backhaul - The key design considerations for small cell backhaul: Capacity, Coverage and Cost - How different backhaul solutions compare against small cell requirements. This presentation is taken from the webinar 'Examining small cell backhaul requirements' - you can watch a recording of the webinar now at - http://cbnl.com/resources/webinars You can also download our white paper 'Easy small cell backhaul' - http://cbnl.com/resources/easy-small-cell-backhaul

1. www.cbnl.com
Next generation thinking
Examining small cell backhaul requirements
15 February 2012

2. Examining small cell backhaul requirements
Agenda
5 mins Are small cells really the next big thing?
Lance Hiley, VP Marketing, Cambridge Broadband Networks Ltd
15 mins The challenges
How will operators deploy small cells?
Key design considerations for small cell backhaul
Julius Robson, Wireless Technology Consultant and Leader, NGMN Small Cell Backhaul Requirements Group
10 mins The solutions
How do different solutions compare against the requirements?
Lance Hiley
10 mins Your questions
Q&A open for 10 minutes
www.cbnl.com 2

3. Who we are
• Formed in 2000
• Global marketshare leader
in line of sight multipoint
microwave technology
• Suitable for LTE network
backhaul
• Selling to 7 of the top
10 mobile operator groups
www.cbnl.com 3

4. Are small cells really
the next big thing?
Lance Hiley
VP Marketing
Cambridge Broadband Networks Limited
www.cbnl.com 4

5. Are small cells really the next big thing?
• 1% smartphone users consume
50% of mobile data
(what happens when
others catch on?)
• More recent and realistic version
of Cisco VNI still shows growth
• New devices and apps will use
whatever capacity is available
• Industry is organising itself to speed
small cells to market
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6. Small cells could be the answer
• Mobile cellular networks were initially designed
for voice
• The popularity of mobile broadband multimedia
services has redefined the RAN and backhaul
“Best Signal Quality in Cellular Networks: Asymptotic requirements of mobile networks: data is
Properties and Applications to Mobility Management in
Small Cell Networks”, Alcatel-Lucent, 2010 dominant
http://jwcn.eurasipjournals.com/content/2010/1/690161
• Mobile networks have to evolve to transport
packet data traffic efficiently: data is different
• Reducing cell size is one of the most effective
ways to improve the spatial reuse of radio
resources and increases network capacity
• Bringing bandwidth closer users improves
customer quality of experience
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7. Small cells could be the answer
Small cells can ease congestion
in busy areas by serving hot
spots and indoor users, leaving
macro-layer to deal with wide-area
high-mobility outdoor users
In this webinar we consider
the implications of this trend
on the backhaul…
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8. The challenges:
How will operators deploy small cells?
Resulting requirements for small cell backhaul
Julius Robson
Wireless Technology Consultant
Leader, NGMN Small Cell Backhaul Requirements Group
www.cbnl.com 8

9. Why deploy small cells?
…for Hot spots and Not spots
macro
Easing congestion New coverage in
within macro coverage addition to macro
A small cell will improve both coverage and capacity,
but the primary motive is important
when considering backhaul requirements
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10. Where will they be?
Congestion on fully
upgraded macro sites
Need to densify
Small
No rooftop space left cells
smaller units needed to
fit available locations
Smaller unit
= less power
= shorter range
Small, low power cells •Small cell sites typically 4-6 m above street
close to users level, on sides of buildings or street furniture
Near street level
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11. Case study: what density of small cells is needed?
•Case study of how demand
density will be supplied with a
mix of HSPA, LTE and small cells
•Gives site densities and spacing
5 sites/km2 dense macro rooftop network
Small cells exceed this in
~2013, requiring below rooftop
Spacing will be lower than average in
pockets of high demand ~100-200m
Variation due to
non uniform deployment
•Assumptions
Demand growth from PA consulting1
Spectral efficiency evolution Ofcom2
Macro site density 5/km2 (Holma3)
Dense macro
1 “Predicting areas of spectrum shortage”, PA Consulting, April 2009
2 "4G Capacity Gains", Real Wireless for Ofcom, Dec 2010
3 “LTE for UMTS: Evolution to LTE Advanced”, Harri Holma, Wiley 2010
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12. The ‘what’ and ‘how’ of backhaul requirements
Coverage
1) Fundamentals Capacity Architecture Small Cell
What Backhaul
Cost
Solution
• Size & weight
• Spectrum bands
• Integration
• Implementation
2) Practicalities Installation
How • Backhaul features
(QoS, Sync etc)
• Availability/latency
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13. The backhaul coverage challenge…
PoP
Small Cells
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14. Backhaul coverage requirements
Coverage from: Points of Presence
− PoP locations: e.g. rooftop macrosites
− PoPs density ~5 sites /km2 PoP
Coverage to: Small cell sites PoP
− Locations:4-6m above street level
− Densities: increasing over time…
− Estimate 30 sites per km2
− ~100-200m spacing
in areas of high demand
Coverage = Connectivity between PoP and small cell sites
…with sufficient QoS
www.cbnl.com 14

15. Quality of Service over Backhaul
•Operators want consumer QoE to be independent of the access topology
•Backhaul QoS should be driven by services offered
•Some aspects of backhaul QoS may change according to deployment scenario:
Small cell deployed primarily for…
Aspect
of backhaul QoS New coverage Easing congestion
@Not Spot @Hot Spot
Where easing congestion, RAN capacity
Availability same as macro relaxed should not be limited by the backhaul
Delay (Latency, jitter) same as macro same as macro
Where coverage overlaps, macro layer
Capacity provisioning relaxed greater than small cell acts as fall back for small cells
“Macrocells might be „quality not quantity‟
….but the reverse is not true for small cells”
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16. ?
Backhaul capacity provisioning
Assumptions
HSDPA 2x2 64 QAM 6 42 Loaded Peak • Modified version of NGMN‟s macrocell
backhaul capacity provisioning [1,2]
DC HSDPA 2x2 64 QAM 12 84
• Includes user plane traffic plus overheads for
transport, X2 and IPsec
• Loaded macrocell throughputs scaled by
LTE 10MHz 2x2 18 75 125% according to 3GPP simulations
• [1] "Guidelines for LTE Backhaul Traffic
LTE 20MHz 2x2 34 150 Estimation", NGMN Alliance, July
2011, http://goo.gl/EWQQg
• [2] “NGMN Alliance – Optimised backhaul solutions
0 50 100 150 200 for LTE, challenges of Small Cell deployment and Co-
ordinated QoS”, NGMN Alliance, Layer 123 LTE/EPC
DL Capacity Provisioning per small cell, Mbps
& Converged Mobile Backhaul, December 2011
• [3] "Further advancements for E-UTRA physical layer
aspects", 3GPP TR 36.814 V9.0.0 (2010-03)
•Loaded figure represents busy times.
•Peak represents maximum capability of the RAN during quiet times
•Small cell sites will initially be single carrier, single cell and single generation, hence
need less backhaul capacity than multi-sector, carrier and operator macros
•This reduces on site aggregation gains so backhaul traffic will be burstier
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17. Backhaul cost requirements
RAN
Equipment
backhaul
Capex
Installation
$ TCO
per site Site rental
Opex Power
leased line
Last mile backhaul
spectrum
Maintenance etc…
Cost per bit is likely to be similar to that of macro sites,
but many small cells will be needed to supply same capacity as a macro
…so cost per small cell site will need to be much lower
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18. Physical design requirements
The small cell and backhaul unit combined should be…
•Small enough to fit in available street level locations
− Planning/zoning may impose volume/dimension restrictions
•Lightweight to facilitate installation Environmental
− A one man lift & mount can reduce costs
Size
•Innocuous rather than sexy Appearance
− Should not draw attention to itself
Power
Planning
•Touch safe and tamper proof
− Some sites may be within reach of the public Reliability
? Permission
Installation &
Connectivity Weight Commissioning
Backhaul/RAN integration
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19. How do different
solutions compare?
Lance Hiley
VP Marketing
Cambridge Broadband Networks Limited
www.cbnl.com 19

20. Small cell backhaul options
Conventional PtP
• For: High capacity
• Against: Coverage awkward, spectrum opex, high installation costs
E-band
• For: High capacity
• Against: High capex and opex
Fibre (leased or built)
• For: High capacity (if you pay enough)
• Against: Recurring charges, availability and time to deploy
Non-line of sight multipoint microwave
• For: Good coverage, low cost of ownership
• Against: Low capacity, spectrum can be expensive
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21. How does it all connect up - wirelessly
Tree (point-to-point) Ring Mesh Multipoint
Key
Links
small cell low capacity
pop high capacity
with redundancy
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22. Point-to-Point (PtP) microwave
PtP Microwave
• Lots of bandwidth microwave frequencies available
at 10-60GHz
− but oversubscribed in many urban centres
• PtP spectrum is link-licensed; high recurring opex
− Area licensing can address this when available
• PtP links use two radios: each requiring
space, installation, energy: high recurring opex
PtP E-band
• 10GHz of spectrum available at 71-76 and 81 GHz
− a window between peaks of high atmospheric absorption
• Light licensing conditions reduces spectrum opex in PtP The most common microwave topology
many markets − For N links, 2N radios
− Dedicated RF channel for each node B served
− Well-suited to constant bit rate traffic
− Well-suited to long links
• Installation of equipment is trickier than conventional − Conventional and E-Band frequencies
PtP
Multiple radios, antenna’s per site to support ring/mesh topologies
makes PtP difficult to deploy at street level
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23. Fibre
Fibre
•Great where already
available, otherwise slow and costly to
install
•High-capacity, low-latency connection
•High recurring cost – even in
competitive markets
UK published fibre pricing
34 mbps 140 mbps 280 mbps 500 mbps
Installation $ 2,000 $2,000 $2,000 $2,000
Yearly rental fees $10,000 $14,000 $20,000 $30,000
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24. Non-line of sight (NLoS) microwave
•Good for
coverage, capacity limited
by available spectrum
•NLoS propagation requires
low carrier frequencies
prized for mobile access
itself
•Free spectrum worth every
penny...but Wi-Fi uses the
entire unlicensed low • Unpaired TDD spectrum could be used for NLoS
frequency spectrum backhaul, but quantity of is small compared to the
LTE and HSPA bands it has to backhaul
•Spectral efficiency
advances unlikely to
compensate: access and
•The 3.5 GHz band is large and
backhaul operating in underused, however 3GPP is planning UMTS
same (NLoS) environment (HSPA) and LTE specifications
www.cbnl.com 24

25. Line of sight (LoS) multipoint microwave
Multipoint microwave designed for street-
level deployment
 High-capacity multipoint microwave
operating at ETSI PMP frequencies:
10.5, 26 and 28GHz. Other bands in
consideration
 Backhaul 8 remote terminals per access Multipoint microwave: fastest
point with up to 300Mbps backhaul capacity growing microwave topology today
− For N links, N+1 radios
− Shared RF channel amongst all sites
 Integrated antenna for maximum − Well-suited to variable bit rate
(bursty) traffic
deployment flexibility/lowest operational − Well-suited to dense environments
− Spectrum under-subscribed in most
cost markets
 Point-to-Multipoint (PMP) aggregates
packet traffic from multiple RT‟s
 Uses 40% less spectrum
 Only one radio per small cell site
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26. Small cell backhaul revolution
 PMP hubs beam high-capacity multipoint bandwidth down urban canyons
 Large numbers of links for small cells, with high peak to average data
traffic favour PMP aggregation capabilities
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27. PMP best fit across small cell backhaul requirements
•LoS PTP and eBand
requirement of two
radios per link impacts
equipment/installation costs
•NLoS wireless capacity
is limited
•Leased line connections
have high repetitive costs
•Wi-Fi range compromises
backhaul application
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28. Architecture contributes to lowering cost of transport
Small Cell TCO (Capex & Opex) •As traffic builds on a small cell
£9,000
network, cost of transport
£8,000 drops with all solutions
£7,000
(blip seen for fibre caused by
transitioning to higher-capacity
Cost per Mb/s traffic carried
£6,000 service)
£5,000
•Multipoint architecture delivers
£4,000
lower cost of transport sooner -
£3,000
from the moment of installation
£2,000
£1,000
£0
32 Mb/s 80 Mb/s 120 Mb/s 150 Mb/s
Fiber, leased Eband PTP
PMP Expon. (PMP)
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29. Summary
•Operators need high-capacity, low-opex
backhaul for small cell network densification
•Small cells needed to supply Hot Spots and
densify network, offloading macro for high-mobility users
•Multipoint LoS microwave is a mature
technology option for backhaul:
− High-capacity
− Short deployment time
− Low cost of ownership
− Spectrum readily available
•Cambridge Broadband Networks VectaStar
Metro meets the small cell backhaul challenge
• Read our whitepaper: http://cbnl.com/resources/white-papers
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30. www.cbnl.com
Your questions
Lance Hiley: lhiley@cbnl.com
Julius Robson: jrobson@cbnl.com
Download the white paper: http://cbnl.com/resources/white-papers
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