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

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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)