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Small Cell Backhaul Requirements
Citation preview
www.cbnl.com
Examining small cell backhaul requirements
Next generation thinking
15 February 2012
www.cbnl.com
Examining small cell backhaul requirements
Are small cells really the next big thing? Lance Hiley, VP Marketing, Cambridge Broadband Networks Ltd
Agenda
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
The solutions
How do different solutions compare against the requirements? Lance Hiley
Your questions Q&A open for 10 minutes
2
5 mins
10 mins
15 mins
10 mins
www.cbnl.com 3
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
Who we are
www.cbnl.com 4
Lance Hiley
VP Marketing
Cambridge Broadband Networks Limited
Are small cells really
the next big thing?
www.cbnl.com 5
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
Are small cells really the next big thing?
www.cbnl.com
Small cells could be the answer
6
Mobile cellular networks were initially designed for voice
The popularity of mobile broadband multimedia services has redefined the RAN and backhaul
requirements of mobile networks: data is
dominant
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
Best Signal Quality in Cellular Networks: Asymptotic Properties and Applications to Mobility Management in
Small Cell Networks, Alcatel-Lucent, 2010 http://jwcn.eurasipjournals.com/content/2010/1/690161
www.cbnl.com 7
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
Small cells could be the answer
www.cbnl.com 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
Why deploy small cells?
A small cell will improve both coverage and capacity,
but the primary motive is important
when considering backhaul requirements 9
macro
for Hot spots and Not spots
Easing congestion
within macro coverage
New coverage in
addition to macro
www.cbnl.com
Where will they be?
Small cell sites typically 4-6 m above street level, on sides of buildings or street furniture
10
Need to densify
Smaller unit
= less power
= shorter range
Small
cells
Congestion on fully
upgraded macro sites
No rooftop space left
smaller units needed to
fit available locations
Small, low power cells
close to users
Near street level
www.cbnl.com
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
Assumptions Demand growth from PA consulting1
Spectral efficiency evolution Ofcom2
Macro site density 5/km2 (Holma3)
11
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
Dense macro
Variation due to
non uniform deployment
www.cbnl.com
The what and how of backhaul requirements
12
1) Fundamentals
What
Coverage
Capacity
Cost
Architecture Small Cell
Backhaul
Solution
2) Practicalities
How
Size & weight Spectrum bands Integration Installation Backhaul features
(QoS, Sync etc)
Availability/latency
Implementation
www.cbnl.com
The backhaul coverage challenge
13
Small Cells
PoP
www.cbnl.com
Backhaul coverage requirements
Coverage from: Points of Presence
PoP locations: e.g. rooftop macrosites PoPs density ~5 sites /km2
Coverage to: Small cell sites
Locations:4-6m above street level Densities: increasing over time Estimate 30 sites per km2 ~100-200m spacing
in areas of high demand
14
PoP
PoP
Coverage = Connectivity between PoP and small cell sites
with sufficient QoS
www.cbnl.com
Macrocells might be quality not quantity
.but the reverse is not true for small cells
Quality of Service over Backhaul
15
Aspect
of backhaul QoS
Small cell deployed primarily for
New coverage @Not Spot
Easing congestion @Hot Spot
Availability same as macro relaxed
Delay (Latency, jitter) same as macro same as macro
Capacity provisioning relaxed greater than small cell
Where coverage overlaps, macro layer
acts as fall back for small cells
Where easing congestion, RAN capacity
should not be limited by the 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:
www.cbnl.com
Backhaul capacity provisioning
16
6
12
18
34
42
84
75
150
0 50 100 150 200
HSDPA 2x2 64 QAM
DC HSDPA 2x2 64 QAM
LTE 10MHz 2x2
LTE 20MHz 2x2
DL Capacity Provisioning per small cell, Mbps
Loaded Peak
Assumptions Modified version of NGMNs macrocell
backhaul capacity provisioning [1,2]
Includes user plane traffic plus overheads for transport, X2 and IPsec
Loaded macrocell throughputs scaled by 125% according to 3GPP simulations
[1] "Guidelines for LTE Backhaul Traffic Estimation", NGMN Alliance, July 2011, http://goo.gl/EWQQg
[2] NGMN Alliance Optimised backhaul solutions for LTE, challenges of Small Cell deployment and Co-
ordinated QoS, NGMN Alliance, Layer 123 LTE/EPC & 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
?
www.cbnl.com
Backhaul cost requirements
17
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
$ TCO
per site
Capex
Opex
Equipment
Installation
Site rental
Power
Last mile backhaul
Maintenance
leased line
spectrum
RAN
backhaul
etc
www.cbnl.com
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 A one man lift & mount can reduce costs
Innocuous rather than sexy Should not draw attention to itself
Touch safe and tamper proof Some sites may be within reach of the public
18
Weight
Size
Power
Installation &
Commissioning
Reliability
Environmental
Backhaul/RAN integration
Appearance
Connectivity
Planning
Permission ?
www.cbnl.com 19
Lance Hiley
VP Marketing
Cambridge Broadband Networks Limited
How do different
solutions compare?
www.cbnl.com
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
20
www.cbnl.com
Tree (point-to-point) Multipoint Mesh
pop
small cell
Ring
Links low capacity high capacity with redundancy
Key
How does it all connect up - wirelessly
21
www.cbnl.com
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
many markets
Installation of equipment is trickier than conventional
PtP
22
Multiple radios, antennas per site to support ring/mesh topologies makes PtP difficult to deploy at street level
PtP The most common microwave topology 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 Conventional and E-Band frequencies
www.cbnl.com
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
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
23
www.cbnl.com
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
frequency spectrum
Spectral efficiency advances unlikely to
compensate: access and
backhaul operating in
same (NLoS) environment
Unpaired TDD spectrum could be used for NLoS backhaul, but quantity of is small compared to the
LTE and HSPA bands it has to backhaul
The 3.5 GHz band is large and underused, however 3GPP is planning UMTS (HSPA) and LTE
specifications
24
www.cbnl.com 25
Multipoint microwave: fastest growing microwave topology today
For N links, N+1 radios Shared RF channel amongst all sites Well-suited to variable bit rate
(bursty) traffic Well-suited to dense environments Spectrum under-subscribed in most
markets
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 point with up to 300Mbps backhaul capacity
Integrated antenna for maximum deployment flexibility/lowest operational
cost
Point-to-Multipoint (PMP) aggregates packet traffic from multiple RTs
Uses 40% less spectrum
Only one radio per small cell site
www.cbnl.com
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
26
www.cbnl.com
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
27
www.cbnl.com
Architecture contributes to lowering cost of transport
28
As traffic builds on a small cell network, cost of transport
drops with all solutions (blip seen for fibre caused by
transitioning to higher-capacity
service)
Multipoint architecture delivers lower cost of transport sooner -
from the moment of installation
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
32 Mb/s 80 Mb/s 120 Mb/s 150 Mb/s
Co
st
per
Mb
/s t
raff
ic c
arr
ied
Small Cell TCO (Capex & Opex)
Fiber, leased Eband PTP
PMP Expon. (PMP)
www.cbnl.com
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
29
www.cbnl.com
Lance Hiley: [email protected] Julius Robson: [email protected] Download the white paper: http://cbnl.com/resources/white-papers Copyright Cambridge Broadband Networks Limited. All rights reserved.
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