grouper.ieee.orggrouper.ieee.org/groups/802/3/10GBT/public/may03/sallaway_1_0503.pdf · 100 200 300 400 500 600 700 800 900 1000 5 10 15 20 25 30 One−sided BW (MHz) Shannon Capacity

1IEEE 802.3 – 10GBT Study Group Interim Meeting

Portsmouth, NH – May 21-22, 2003

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Phy Vendor’s Perspective

Multi-vendor presentation:Broadcom

Vativ TechnologiesMarvell



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Primary goal: Define necessary channel requirements formultiple vendors to agree to the feasibility of a 10G phy implementation

1. Compute theoretical capacity on standardized cable channels• Cat 5e, Cat 6, Cat 7 (classes D,E,F)

• Based on unscaled measured data

2. Channel requirements needed for 10G• “Fantasy” Cat 6



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Cat 5e, Cat 6, Cat 7



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• Standard 2 or 4** connector 100m terminated channel

– Differential measurements

– Channels pass cable tester

• Alien crosstalk measured as power sum from 7 cable bundle

. . .

6"

Cable Bundle

6x4 Outer Crosstalkers1x4 Inner Victim

LucentLucent PATCHM AX

3 6 1 2

M odular Jack

M odular Pane l

Cable (245 ft)

Patch Cord (9 ft/5 ft)

Equ ip ment Cord (9 ft/5 ft)

1 2

3 4

Luc entLuc ent PATCHM AX

M odular Pane l

CP Cab le (50 ft) M odular

Jack

3 6 1 2


LucentLucent PATCHM AXLucentLucent PATCHM AX

3 6 1 23 6 1 23 6 1 2

M odular Jack

M odular Pane l

Cable (245 ft)


Equ ip ment Cord (9 ft/5 ft)

1 2

3 4

Luc entLuc ent PATCHM AXLuc entLuc ent PATCHM AX

M odular Pane l

CP Cab le (50 ft) M odular

Jack

3 6 1 23 6 1 23 6 1 2


**Ref: Terry Cobb, Avaya, 2003



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Insertion Loss

PSNEXT

PSFEXT

Return Loss

• Limit lines extrapolated after 100MHz



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2 Connector PSANEXT 4 Connector* PSANEXT- exceeds proposed limit line

*2 near end connectors only

• Both channels pass Cat 5e cable tester



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• Cable terminated in 100 ohms

• Narrowband interferers have insignificant impact on theoretical capacity

• Broadband noise level below -155 dBm/Hz– Similar results for Cat 6

Hallway LAB Network Closet



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• Based on unscaled measured data from 100m - 2 connec tor channel – Background noise –155dBm/Hz

– Not representative of worst case channel

100 200 300 400 500 600 700 800 900 10004.5

5

5.5

6

6.5

7

7.5

8

8.5

9

9.5

One−sided BW (MHz)

Shan

non

Capa

city i

n GB

ps

Capacity with AWGN and ANEXT with 0dB of ANEXT cancellation

Capacity = 9.00 Gbps @ 720MHz



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Insertion Loss

PSNEXT

PSFEXT

Return Loss



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Insertion LossLimit Line

ProposedLimit Line fromNov ’02 Tutorial

• 4 Connector channel exceeds proposed ANEXT limit li ne



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• Based on unscaled measured data from 100m - 4 connec tor channel – Background noise –155dBm/Hz

100 200 300 400 500 600 700 800 900 10005

5.5

6

6.5

7

7.5

8

8.5

9

9.5


Shan

non

Capa

city

in G

Bps


Capacity = 9.39Gbps @ 800MHz



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Insertion Loss

PSNEXT

PSFEXT

Return Loss

* Cable: Siemon Co. Cat 7 TERA Channel



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*Data supplied by Nexans



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• Narrowband interferers suppressed

• Broadband noise level well below –155 dBm/Hz



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• Based on unscaled measured data from 100m - 4 connec tor channel– Background noise at –160dBm/Hz– ANEXT = measured Cat 6 reduced by 40 dB

100 200 300 400 500 600 700 800 900 100010

15

20

25

30

35

40

45

50


Shan

non

Capa

city

in G

Bps


Capacity = 49.36Gbps @ 1000MHz

Using limit lines reduces max capacity to37.71Gbps @ 985MHz



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• Capacity calculations with measured data indicate t hat 10 Gigabit data transmission over 100m Cat 5 or Cat 6 UTP cabl es is not feasible

– Many basic implementation impairments neglected in this simplified analysis

• Actual capacity will be worse

• Alien crosstalk is a fundamental limit– Must be reduced by some means – suggestions are welc ome

– Is disallowing cable bundles, adjacent patch panel locations, or multi-connector

channels an acceptable marketplace solution ?

• Capacity calculations with measured data indicate 1 0 Gigabit data transmission over 100m Cat 7 may be possible

– Further investigation with actual line codes and mo re accurate models warranted



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Fantasy Cat 6



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• 10GBASE-T may be possible on newly specified improved UTP cable with sufficiently low alien cros s talk

– “Fantasy Cat 6”

• ANEXT is only one part of the overall noise budget– ANEXT must be sufficiently small to permit realizable levels for other

impairments

• ADC quantization noise and sample clock jitter are t he next largest impairments

– Residual NEXT/FEXT/echo/ISI, round off noise, transmit distortion, adaptation noise, background noise, etc. also contribute



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• Assuming a cable with sufficiently low ANEXT, analog-to-digital conversion is the next dominant noise source

– Determined by the resolution and timing jitter of th e ADC

– Reduces noise budget available for ANEXT

• Assume:– Quantization noise is AWGN

– Background noise is AWGN

– ANEXT is the only other uncancelled noise source

– 416 MHz baseband PAM



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• Slicer symbol SNR* = the average PAM-modulated symbo l SNR to achieve SER=10-12

• PAM10 SNR* = 32.21 dB

• MMSE−DFE SNRMMSE = exp{�ln(1+SNR(f))df/B} −1 and the corresponding channel capacity C= �log2(1+SNR(f))df

– Channel SNR(f) is determined by insertion loss, ali en crosstalk, quantization noise (Vpp=2V) and background noise (-155dBm/Hz)

– Target SNRMMSE=SNR*−coding gain+design margin

– Coding gain = 6dB (TCM),

– Design margin should cover the impact of all real-w orld system defects, including:

ü <6dB coding gainü Clock jitterü Uncancelled echo/NEXT/FEXT/ISI

ü Analog non-linearitiesü Analog noiseü Arithmetic noiseü “Other” – system margin



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12

9

6

12

9

6

Design Margin

(dB)

Limit lineMeasured data

NANA21.130.738.21

19.540.819.523.535.21

17.829.117.818.932.21

11

NANANANA38.21

NANANANA35.21

NANA17.824.132.21

10

Channel Capacity (Gbps)

ANEXT reduction

(dB)

Channel Capacity (Gbps)

ANEXT reduction

(dB)

Target SNRMMSE

(dB)

ADC ENOB (bits)



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• Based on unscaled measured data from 100m- 4 connect or Cat 6 channel with

– 30dB ANEXT reduction– −155dBm/Hz background noise

100 200 300 400 500 600 700 800 900 10005

10

15

20

25

30


Shan

non

Capa

city

in G

Bps


Capacity = 28.80 Gbps @ 800MHz



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• 10GBASE-T is not feasible over a large portion of e xisting Cat 5e and Cat 6 cable plants

– ANEXT is the fundamental limit

• A new cable matching Cat 6 performance with suffici ently reducedANEXT could support 10GBASE-T

– 30-35dB ANEXT reduction necessary

– Requires characterization beyond current 250MHz Cat 6 spec

– ENOB > 10 bits for PAM10

• Existing standard Class F cable could support 10GBA SE-T– No further characterization necessary

– ENOB >10 bits for PAM10

• Once the appropriate channel medium is selected, a coded modulation scheme needs to be chosen to optimize pe rformance

Documents

grouper.ieee.orggrouper.ieee.org/groups/802/3/10GBT/public/may03/sallaway_1_0503.pdf · 100 200 300 400 500 600 700 800 900 1000 5 10 15 20 25 30 One−sided BW (MHz) Shannon Capacity