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Keeping up the momentum: The importance of innovation to keep networks fit for the future Dr Tim Whitley
MD Research & Innovation, BT Distinguished Engineer
2
Trends
• Increasing consumer and business data usage:
– Device penetration (tablets, smartphones, smart TVs);
– Video usage across all device types;
– Internet of things, ‘wearables’ etc..
• Increased bundling of services:
– Convergence of content/TV and broadband;
– Convergence of fixed and mobile;
• Voice heading towards being an application on IP.
Challenges for BT
• To provide enough capacity to keep up with demand.
• To devices that customers want to use, wherever they are and when they want to use it.
• At reasonable cost.
• To offer seamless connectivity requires integration of fixed and mobile networks.
• Manage implications for core network
Context
3
Access – BT’s Broadband Heritage
• August 2000: BT Launched 500kbps ADSL broadband
• September 2004: BT removes distance limitations for ADSL
• March 2006: BT Launches 8Mbps DSL Max
• April 2008: BT Launches 24M Wholesale Broadband Connect
• January 2009: BT Infinity / Fibre Broadband launched
• April 2012: 80Mbps FTTC launched
• November 2012: 10G PON trial in Cornwall
• August 2013: 300Mbps Infinity product launched
• Spring 2014: Scale Vectoring Trial
• Summer 2014: G.Fast technology trial
Narrowband
Broadband
Copper speeds: advances over time
VDSL ADSL
G.fast
4
Fibre to the Cab Fibre to the DP Fibre to the Premise
~4M locations <106MHz, Typ ~35m length
~89k locations <17MHz, Typ 350m length
5600 locations <2.2MHz, Typ 3.5km length
The access network
~29M locations
5
Driving faster speeds
• FTTC – Vectoring
• FTTRN – VDSL closer to the customer
• FTTDP – G.Fast
• FTTP
Extending reach
• We are innovating to extend benefits of faster access to the final c. 10% of coverage
• Copper rearrangement
• Broadband regenerators for ADSL
• Microwave wireless to the cabinet
• VDSL amplifiers
• Fibre to the remote node (mini DSLAMs)
Access – broadband Innovations
Vectoring Cabinet
6
The impact of crosstalk and vectoring
• Crosstalk is due to coupling between pairs in a multi-pair copper cable and limits FTTC speeds.
• Increasing cable fill through customer take-up increases crosstalk and reduces line-rates.
• By calculating a “pre-compensation” factor for each line, the crosstalk can be cancelled in the DSLAM.
• The technique for doing this is called “Vectoring”, and is conceptually similar to noise cancelling headphones.
• Openreach has trialled six vectored cabinets with c.1000 live customers in Braintree and Barnet. Phase 2 trials are now underway.
line 1
line 2
line 3
Signal 1
Signal 2
Signal 3 Cable binder
0
20000
40000
60000
80000
100000
120000
200 300 400 600 900 1200 1800
Max
Attn
Bit
Rate
(kbp
s)
Cable Length
Vectoring gain (laboratory measurement)
Maxim
um
Do
wn
str
eam
bit
-rate
(kb
it/s
)
Crosstalk generation within a cable
Performance without Vectoring Performance with Vectoring
(m)
7
Pushing fibre deeper into the network: the Distribution Point
• Beyond the green cabinets, BT has overhead and underground DPs with: • An average of ~8 customers connected;
• Can have >16 customers in some cases.
• Space is limited and they are exposed to the elements.
• The typical distance from the DP to the customer is ~35m making it the ideal location for delivering very high speeds.
• A new technology (G.fast) is being standardised in the ITU: • Enables speeds of up to 1 Gbit/s;
• Commercial G.Fast equipment is expected in H2 15/16.
Typical pole DP
serving 12 customers
Typical distribution
footway joint box
8
We have trialled G.Fast in the network • Trial had three customers connected to one DP
• The network was overlaid to prevent harm to existing services, but used existing duct infrastructure
• Chart shows best and worst case performance
• Physics of G.Fast worked as expected
• Vectoring proved to be critical in delivering the top speeds
19m
47m 66m
10G backhaul
19m 66m
19m 66m
9
BT is opening a new, purpose-built, ultrafast broadband lab at our Adastral Park R&D centre in Ipswich • G.Fast has demonstrated potential that now needs to be
tested and verified.
• We will study the full technical capabilities of G.Fast hardware designed by leading system vendors.
• We will continue to play a proactive role in developing G.Fast standards in the ITU.
• It’s crucial that we stay ahead of the curve for the benefit of our customers and shareholders.
Emulation network enables replication of different real-world final-drop topologies
DP and CPE installations allow a full range of performance and
operations tests
10
FTTP – 10G and beyond
• GPON provides 2.5Gbit/s downstream, 1.2Gbit/s upstream
• XG-PON1 provides 10Gbit/s downstream, 2.5Gbit/s upstream
• Exploiting existing Fibre Network with separated wavelengths
• XG-PON and GPON coexist on the same fibre
• No change to Optical Distribution Network (ODN)
• WDM1r (Filter) component already in place
• We are working on NG-PON2 which provides 40Gbit/s downstream and 10Gbit/s upstream on a single PON
1.24Gbit/s & 2.5Gbit/s (1310nm & 1270nm)
WDM1r XG-PON1 ONT
GPON ONT
2.5Gbit/s & 10Gbit/s
(1490nm & 1577nm) GPON OLT
GPON
system
XG-PON1
system XG-PON1 OLT
Power splitter
GPON ONT
11
Access fibre deployment and new services will drive future core bandwidth demand
• Current core traffic growth CAGR = 45%. • Bandwidth demand analysis to 2033 suggests core
requirement of c.12Tbit/s by 2020.
Key future demand drivers: – Over the Top content;
– Video on Demand;
– 4k/8k content delivery;
– Cloud-based applications;
– HD Video-calling;
– Rich media webpages;
– Software package size growth;
– Customer expectations of speed.
Potential long-term core capacity requirements
Time of day activity scenarios have been used to model
bandwidth demand of different user types
Future demand mitigation: – Improved video coding;
– Time-shift delivery techniques.
Modelling suggests c 25 to 30 fold core capacity increase over the next ten
years -
10
20
30
40
50
60
70
2013 2018 2023 2028 2033
Core
traf
fic (T
bit/
s)
Low Scenario
Mid Scenario
High Scenario
12
BT’s upgrades core transmission roughly every ten years...
1980 1990 2000 2010 2020
100Gbit/s
155Mbit/s
2.5Gbit/s
10Gbit/s
2Mbit/s
64Kbit/s
Year
Ban
dw
idth
34Mbit/s
622Mbit/s
40Gbit/s
PDH
Private Circuits
Kilostream
PSTN
SDH MESH
Megastream
2-155 Mbit/s
PSTN
1Tbit/s
SDH rings
155M -2.4G Broadband,
ATM & IP
UBB 1G-10G
21C WDM 1G-10G
NG-WDM
1G, 10G, 40G, 100G
We are now deploying 100Gbit/s coherent optics
13
The Next Generation: 400G & Terabit Trials
Norwich
Adastral
park
Newmarket
Cambridge
Colchester
Basildon
Bishops Stortford
BT Tower
Wood green
77km83km
68km
29km
64km
58km
62km
52km
24km
50.7km
13.5km
14km
Ipswich
2015 2013 2011 2012 2014
1T
2T
100G
Coherent
40/100G
400G & 200G (16-QAM)
800G
Super channel
1.4T Alien Flexgrid Super channel
2016
2T & Beyond
2010
BT Tower
BT Adastral
Park
Cambridge
TNOC
S/W Configurable modulation formats
Alien Wavelengths
14
The Next Generation: Gridless & Optical Superchannels • Current WDM has rigid 50GHz grid structure.
• Future gridless infrastructure permits improved fibre utilisation (spectral efficiency).
Example: 1.4T “Superchannel” comprising 7 x 200G (16-QAM) subchannels
15
Pushing the boundaries
100G
Superchannel
• We have demonstrated real-time 2.2T Transport over managed Flexgrid infrastructure:
– 11 x 200G 16-QAM Superchannel;
– 33.5GHz subcarrier spacing giving a spectral efficiency of 5.97bits/s/Hz, more than 49% improvement over conventional 50GHz grid.
• We are working with partners to develop our understanding of capacity management, for example:
– Demonstrating configurable Superchannel alongside multiple 100G 50GHz grid channels;
– Working with Huawei U2000 management system.
400GHz
2.2T
(11 x 200G 16-QAM)
100G
2.2T Superchannel
Configurable Superchannel operating alongside 100G grid
channels
16
The next challenges are control, flexibility and vendor interoperability... SDN datacentre & network orchestration
SDN orchestrating the provision of virtualised network functions
Datacentre with general purpose H/W suitable for NfV
• Reduced costs through consolidating functions
• Reduced operational costs
• Rapid provision of new services globally
• Software oriented innovation (including Open Source)
• Open standard control and orchestration equipment
• Setting up optical and Ethernet circuits on the fly
• Control of flexgrid bandwidth and optical modulation formats
• Multilayer operation allowing time of day router bypass
Software Defined Networking (SDN) Network functions Virtualisation (NfV)
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