sckipio's g.fast presentation to broadband world forum asia 2015 by charles chiu

Apr 15, 2023Sckipio | How Do We Make G.fast Real 1

HOW DO WE MAKE G.FAST REALThe Best Practices for Deploying G.fast

Charles ChiuDirector, Business Development, Sckipio Technologies

Apr 15, 2023Sckipio | How Do We Make G.fast Real

2

5 SECRETS TO SUCCEEDING IN G.FAST DEPLOYMENTS


3

SECRET #1: MODEL THE BUSINESS


4

WHAT’S THE BIG G.FAST IDEA?Leverage your existing copper wiring to deliver ultra broadband to the masses


5

PROBLEM OF SUBSCRIBER DROP

•Trenching on premises

•Installation scheduling & cost

•Right of way issues

•Roll-out delays due to capacity of installers

•Very expensive overall

Average 1.8km

Average 500m

Average 100m

$$$


6

Central Office

VDSL2800-1,000 metersLess than 140Mbps

G.fast Distribution Point30-400 metersUp to 1Gbps

Fiber to the HomeOver 1 KilometerOver 1Gbps

Fiber

Twisted Pair


7

G.FAST IS VERY FAST!

700Mbps

100 meters

500Mbps

200 meters

350Mbps

300 meters

270Mbps

400 meters

150Mbps

500 meters

Numbers are aggregate upstream/downstream

16 lines with crosstalk


8

G.FAST GOING FURTHER

700Mbps

100 meters

500Mbps

200 meters

350Mbps

300 meters

270Mbps

400 meters

150Mbps

500 meters

Numbers are aggregate upstream/downstream

16 lines with crosstalk


9

NEW ≠ MORE EXPENSIVE

Cost per port

FTTH

Cost per port

VDSL VECTORING

Cost per port

G.FAST

G.FAST Lowest cost

per port


10

SECRET #2: FOCUS ON POWER


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IMPORTANCE OF POWER

• G.fast leverages reverse power

• Everything driven from power budget

– Distance it can go– Size of unit– Overall cost


12

Cost vs. Power ConsumptionImpact of power consumption on the equipment housing cost

• Reference: Adtran ITU-T contribution 2012-02-4A-058R1, a case study done in 2012

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60 70

Nor

mal

ized

Com

plex

ity

Max Power Dissipation (Watts)

16

with DO

no DO

16

24

24


13

WHAT DRIVES POWER CHOICES

• Discontinuous operation

• Vectoring

• Training times and low power states

• G.int and network management


14

POWER COMPARED TO VDSL

• Time Division Duplexing • Frequency Division Duplexing

• Fast retraining • Slow retraining

• Low power default • Default: Always broadcasting

• Power down each port • All ports active

• Fast vector pairing • Slow vector pairing

VDSL


15

SECRET #3: UNDERSTANDING VECTORING


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CROSSTALK IS BANDWIDTH KILLER

0 20 40 60 80 100 120 140 160 180 200-160

-150

-140

-130

-120

-110

-100

-90

-80

-70Channel and FEXT for BT 100m line

Frequency [MHz]

Sig

nal and F

EX

T [

dB

m/H

z]

10dB

Received signal FEXT sum


17

G.FAST = VECTORING


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DYNAMIC VECTORING IS KEY

• Real time

• Must respond in time

• Built-in vectoring critical


19

SECRET #4: UNDERSTAND THE TRANSITION FROM VDSL


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HOW G.FAST DIFFERS FROM VDSLParameter VDSL G.FAST

Frequency Range Up to 30MHz (30a) 2-106MHz, 2-212MHz (future)

Max Rate Up to 250Mbps (30a) and 150Mbps (17a) for short loops, real-world is 30-80Mbps

1Gbps over short loops, exceeding 500 Mbps over real 100m lines

Modulation OFDM OFDM

Number of carriers 4K (8K for future V+) 2K (for 106MHz profile)

Multiplexing scheme FDD TDD, synchronized among the different copper pairs

Symbol time ~250 μsec (17MHz profile) ~20 μsec

Vectoring Via G.993.5 Supported, with adaptations needed for higher frequency

Tx power Varies by profile, 14.5dBm 4dBm

FEC RS + Trellis code RS + Trellis code


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HOW G.FAST DIFFERS FROM VDSL

Parameter VDSL G.FAST

Downstream/Upstream ratio Fixed Configurable: 90:10 to 30:70

Customer self-install Questionable. i.e. rates become marginally low

Yes

xDSL Spectral compatibility Issues with 17M/30M mixIssues with CAB/DP Mix

Yes, fresh start with new frequency band

Retrain time Very long (30-90 second range) Very short – few seconds

Rate adaptation Very slow, 128 carriers at a time, SOS not robust

Very fast, quick and robust adaptation – within few msec

Low power mechanisms Under definition, expected savings up to 50%, very slow wake up time

Specified from day one, discontinuous operation, scales with traffic rate


22

CO-EXISTENCE WITH VDSL

• VDSL and G.fast can co-exist

• Separate by frequency

VDSL

G.FAST

Up to 17Mhz

20-106Mhz


23

VDSL & G.FAST ARE USUALLY NOT CO-LOCATED

•Most operators install VDSL far from the DP

•When deploying G.FAST, legacy VDSL service will continue without interferences

•The service can be gradually upgraded to G.FAST

Average 500m

Average 100m

VDSLG.FAST

20-106MHz

17MHz

Co-Existence


24

APPROACH MOST ARE TAKING

• Bring fiber to the DPU

• Keep infrastructure as is (ADSL/VDSL)

• Using diplexer in the DPU to merge the lines

• Migrate gradually to G.fast over time without truck roll


25

VDSL FALLBACK• Not required by ITU or Broadband Forum

• Most service providers won’t deploy

• Don’t want to double pay for existing VDSL customers – They already have VDSL running, no need to pay again

• Cross-technology vectoring is challenging– If integrated into a single chip – extremely complex and inefficient

• If needed, can be implemented with two-chip solution


26

SECRET #5: FIND THE SWEET SPOT


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DEPLOYMENT OPTIONS


28

MDU IS KEY USE-CASE


29

DPU IN THE BASEMENT

• Smaller buildings

• Fiber to the DPU

• DPU in basement

• 1:16 today to CPE

• 24 feasible now, 48 future


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DPU ON EACH FLOOR

• FTTF (Fiber to the Floor)

• Larger buildings

• Fiber to riser (WDM-PON, GPON)

• DPU on each floor

• 1:16 for each floor

• 24 feasible now, 48 future

x16

x16

x16

x16

x16

Fiber

.

.

.Floor 1

.

.

.

.

.

.Floor 2


31

OUTDOOR PLANT

• Row housing

• Fiber down street

(WDM-PON, GPON)

• DPU to each building or

section of building

• Reverse power feed

from CPE to power

DPU


32

5 SECRETS TO SUCCEEDING IN G.FAST DEPLOYMENTS

1. Model the business

2. Focus on power

3. Understand vectoring

4. Understand the transition from VDSL

5. Find the sweet spot

ULTRA BROADBAND FOR THE MASSES

sckipio's g.fast presentation to broadband world forum asia 2015 by charles chiu

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