IEEE802.3 Interim January 200310GBASE-T
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10GBASE10GBASE--T Tutorial OverviewT Tutorial Overview
William JonesSolarflare Communications
[email protected]_1_9_2003_overview.pdf
IEEE802.3 Interim January 200310GBASE-T
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Introduction: Realizing 10GBASEIntroduction: Realizing 10GBASE--TT
• Application Overview• Cabling & Impairments• Strawman System• Implementation• Performance Results• Conclusion
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Applications OverviewApplications Overview
• 10-Gb/s Ethernet connections <= 100m• Utilize installed base of structured Cat 5e UTP• Upgrade from 1000BASE-T
10GBase-TTransceiver
11/4/2002
MAC 10GBase-TTransceiver MAC
Cat5e UTP(4 pairs)
up to 90m
Wallplateor
Patch Panel
Wallplateor
Patch Panel
up to 5m up to 5m
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Channel ImpairmentsChannel Impairments
R
THYBRID
R
T HYBRID
R
THYBRID
R
T HYBRID
R
THYBRID
R
T HYBRID
R
THYBRID
R
T HYBRID
NEXT14
NEXT12
NEXT13
FEXT14
FEXT13
FEXT12
Far Echo
Near Echo
Alien Crosstalk, EMI
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Characterization vs. SpecificationCharacterization vs. Specification
• Cat 5/5e cable must be high quality with minor structural variations to meet TIA-568 requirements
• 100 MHz (or 250 MHz) “limit” imposed by TIA qualification requirements– not the physical limitations of the cable
• Cable properties stable beyond 500 MHz– depends mainly on transmission line geometry and
construction materials
• Minor structural variations and connector discontinuities affect channel transmission, but not catastrophically
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Cat 5e Channel: Insertion LossCat 5e Channel: Insertion LossMeasured Cat 5e 100 Meter Channel Insertion Gain at 20 C
0 50 100 150 200 250 300 350 400 450 500-60
-50
-40
-30
-20
-10
0
Frequency (MHz)
Inse
rtion
gai
n (d
B)
Manufacturer AManufacturer BManufacturer CCat 5e limitExtended limit
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Cat 5e Channel: NEXTCat 5e Channel: NEXT
0 100 200 300 400 500 600-80
-70
-60
-50
-40
-30
-20
-10
0
Measured Pair-to-pair NEXT Coupling into Cat 5e Pair 1
Frequency (MHz)
Inse
rtion
gai
n (d
B)
NEXT12NEXT13NEXT14
Cat 5e limitExtended limit
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Cat 5e Channel: FEXTCat 5e Channel: FEXT
0 50 100 150 200 250 300 350 400 450 500-100
-90
-80
-70
-60
-50
-40
Measured Pair-to-pair FEXT Coupling into Cat 5e Pair 1
Frequency (MHz)
Inse
rtion
gai
n (d
B)
FEXT12FEXT13FEXT14
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Alien NEXTAlien NEXT
0 50 100 150 200 250 300 350 400 450 500-80
-70
-60
-50
-40
-30
-20
Frequency (MHz)
Inse
rtion
gai
n (d
B)
Adjacent connectorNon-adjacent connectorCat 5e NEXT limitExtended limit
Single (4-pair cable) disturber, 40 meter length unbundled
Cat 5e Power Sum Alien NEXT vs. Patch Panel Position
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EMI EMI -- EmittedEmitted• >100 MHz on Cat 5e can meet FCC Class A
~12 dBm launch power limitation• < 500 MHz limits larger high frequency emissions
0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 02 0
2 5
3 0
3 5
4 0
4 5
5 0
5 5
6 0
W o rs t-C a s e R a d ia te d E m is s io n s a t 3 M e te r s - C a t 5 e U T P
F re q u e n c y (M H z )
Elec
tric
field
(dB
uV/m
)
- 8 0 d B m /H z s ig n a lF C C C la s s A l im i tF C C C la s s B l im it
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Baseline RequirementsBaseline Requirements• ~ 10 dBm Transmit power• ~ 400 MHz Bandwidth• ~ 40 dB Echo & NEXT Cancellation, ~ 20 dB FEXT Cancellation• Alien NEXT suppression for crowded installations
Received Signal & Residual Noise Terms
-160.00
-150.00
-140.00
-130.00
-120.00
-110.00
-100.00
-90.00
-80.00
0 50 100 150 200 250 300 350 400
Frequency (MHz)
PSD
ref
to
Inpu
t (d
Bm
/Hz)
-20.0
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
SNR
(dB
)
Rcv Sig
Res Echo
Res NEXT
Res FEXT
Res ANEXT
Bkgnd
SNR
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StrawmanStrawman System: PAMSystem: PAM--10 Coding10 Coding
• Given the characteristics of the channel/disturbers, capacity is maximized with an analog bandwidth around 400MHz
• 10Gbps is achieved with a baud rate of 833MHz and 12 bits/baud or 3 bits/pair (4 pairs)– Minimum requirement of PAM8 for uncoded operation
• PAM9 may be sufficient for Ethernet control symbols• PAM10 needed for both control and Trellis coding• Extension of 1000BASE-T
– 4D, 8-state Trellis code (one dimension per pair)– 6 dB coding gain relative to uncoded 10PAM
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Comparison With 1000BASEComparison With 1000BASE--TT
High-Performance FEXT cancellation
No specified FEXT cancellation
High-Performance NEXT cancellation
Moderate NEXT cancellation
833 Mbaud, ~400 MHz used bandwidth
125 Mbaud, ~80 MHz used bandwidth
Full duplex echo-cancelled transmission
Full duplex echo-cancelled transmission
10-level with Trellis code across pairs
5-level with Trellis code across pairs
Multilevel coded PAM signaling (3-bits/symbol)
Multilevel coded PAM signaling (2-bits/symbol)
Straw Man 10GBASE-T1000BASE-T
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PCS SER & BER Straw Man GoalPCS SER & BER Straw Man Goal
19 20 21 22 23 24 25 26 2710
-14
10-12
10-10
10-8
10-6
10-4
10-2
100
Coded PAM10 simulation SERCoded PAM10 Theory SERCoded PAM10 Theory BER
1000BASE-TReqm’t
25.3 dB
• For an aggregate slicer SNR of 25.3 dB with five dominating noise terms requires individually around 32 dB SNR
Slicer Input SNR (dB)
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Implementation Requirement Implementation Requirement -- ISIISI• Pre- & Post-Cursor Interference from limited
Bandwidth• Post-Cursor Dominates (>100 terms)• Feedforward & Decision
Feedback EqualizationSolution
FeedForwardEqualizer
DecisionFeedbackEqualizer
Slicer
_+
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Implementation Requirement Implementation Requirement -- EchoEcho
• Full duplex needed for limited BW• Compromise hybrid for Tx/Rx isolation• Impedance mismatches
require residual echocancellation
• > 40 dB rejection
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Implementation Requirement Implementation Requirement -- NEXTNEXT
• High-level interference from transmitters• Very long response time• > 40dB NEXT cancellation
wireline
Tx Channel 0
Rx Channel 1(target rcvr)
NextCoupling
wireline
Rx Channel 0(victim rcvr)
Tx Channel 1(interfering xmtr)
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Implementation Requirement Implementation Requirement -- FEXTFEXT
• Pre- and post-cursor elements of interference• Based on an equal-level FEXT (ELFEXT) model• Uncompensated in 1000BASE-T• Must be cancelled in 10GBASE-T• > 20 dB cancellation
wireline
Tx Channel 0
Tx Channel 1(interfering xmtr)
FextCoupling
wireline
Rx Channel 0(victim rcvr)
Rx Channel 1(target rcvr)
chanelffext HHH ⋅=
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Challenging ImplementationChallenging Implementation
• A new approach to problem solving needed to meet SNR requirement (> 25.3 dB)
• Efficient reuse of resources in MIMO modeling
• Utilization of parallel structures
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Traditional Signal ProcessingTraditional Signal Processing• Echo & NEXT cancellation
SISOSISOSISOSISO
SISOSISOSISOSISOSISOSISOSISOSISO
SISOSISOSISOSISO
T4T3T2T1
++++ ++++ ++++ ++++ R4
• 16 Single Input Single Output (SISO) processing elements(scalar filters)
• With canceller taps on the order of several hundred10 Tera Operations (TOps)!
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Modern Signal ProcessingModern Signal Processing
• Echo & NEXT Cancellation
R4
T4T3T2
MIMO
T1
• One Multiple Input Multiple Output (MIMO) processingelement (matrix filter)
• Exploits correlation to reduce interference common to all received channels
• Enables massive reuse of computing resources
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Modern Signal ProcessingModern Signal Processing
• Data recovery & Fext cancellation
d1
d2
d3
d4
T1
T2
T3
T4
R1
R2
R3
R4
H1
F21
F31
F41
MIMOCHANNEL
MUD
d1
d2
d3
d4
• Multiuser Detector (MUD) of MIMO channel providessimultaneous data decisions & interference removal
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Parallelizing FIRsParallelizing FIRs• One high rate N tap filter
( ) )()( 21
120 zHzzHzH −+=
x(n)H(z)
y(n)
H0(z)
H1(z)
H1(z)
H0(z)
Z-1
x(n)
Z-1
+
+ +
Z-1
y(n)
2
2
2
2
• Good for clock limited or high speed applications• Four half rate N/2 tap filters• Equivalent number of operations per unit time
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Efficient Efficient Parallelization Parallelization
H0(z)
H0(z)+H1(z)
H0(z)
Z-1
x(n)
Z-1
+
+ +
Z-1
y(n)
2
2
2
2+ +_
_
• Four filters reduced to three
• 25% improvement in efficiency
•Greater efficiency with greater parallelism
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Digital Circuit Straw Man GoalsDigital Circuit Straw Man Goals
• Puts total DSP requirements at 1.5 Tera Operations (TOps)
• Quad 1000BASE-T requires 1.0 TOps 150% increase in possible aggregation with 50%
increase in complexity today!
• CMOS technology
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Analog Circuit Straw Man GoalsAnalog Circuit Straw Man Goals
• Transmitter: DAC & Line driver– >40 dB Linearity– 450 MHz Bandwidth
• Receiver: Hybrid, LNA & ADC– >8 bits ENOB– 833 MSPS
• Clock – 833 MHz
• CMOS technology
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ISI Performance ISI Performance -- After EqualizationAfter Equalization
0 0.5 1 1.5 2 2.5 3 3.5 4x 108
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency
Spec
trum
(dB)
Equalized Signal
Residual ISI
• FFE scales to produce unit variance hard decisions
Tx MAG MAG Rx ENFX EQCat 5e cable
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ISI Performance ISI Performance -- Symbol StreamSymbol Stream
a)
b)
0 1 2 3 4 5 6 7 8 9 10
x 104
-2
-1
0
1
2a) Rx Far End Signal b) Slicer Input Vs. time
0 1 2 3 4 5 6 7 8 9 10
x 104
-2
-1
0
1
2
MAG MAG Rx ENFX EQCat 5e cable
a b
Tx
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Echo Performance Echo Performance -- SNR @ DetectorSNR @ Detector
0 0.5 1 1.5 2 2.5 3 3.5 4x 108
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency
Spec
trum
(dB)
Equalized Signal
Residual Echo
• FFE scales to produce unit variance hard decisions
Tx MAG MAG Rx ENFX EQCat 5e cable
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NEXT Performance NEXT Performance -- SNR @ DetectorSNR @ Detector
Tx MAG MAG Rx ENFX EQ
0 0.5 1 1.5 2 2.5 3 3.5 4x 10
8
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency
Spec
trum
(dB)
Equalized Signal
Residual Next(3)
Cat 5e cable
• FFE scales to produce unit variance hard decisions
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FEXT Performance FEXT Performance -- SNR @ DetectorSNR @ Detector
• FFE scales to produce unit variance hard decisions
Tx MAG MAG Rx ENFX EQCat 5e cable
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Total Total Slicer Slicer SNRSNR
Tx MAG MAG Rx ENX EQCat 5e cable
0 0.5 1 1.5 2 2.5 3 3.5 4x 10
8
-60
-50
-40
-30
-20
-10
0
10
Frequency
Spec
trum
(dB)
Equalized Signal
Total Noise
Total Noise Power Goal (-25.3) • FFE scales to produce unit variance hard decisions
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Sequenced StartupSequenced StartupN E, P F DONE
DONEFE, TNSLAVE
MASTER
N = ECHO/NEXT Canceller Convergence T = Tim ing AcquisitionP = Phase Adjustment
F = FEXT Canceller ConvergenceE = Equalizer Convergence
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Summary: Realizing 10GBASESummary: Realizing 10GBASE--TT
• Careful attention to media characterization beyond 100MHz
• Evolution of 1000BASE-T
• Modern signal processing methods
• Feasible CMOS realizations of digital & analog circuits
• Q&A