Channel Data Capacity Analysis for B10GAUTO

Eric DiBiaso, Bert Bergner

November 11-14, 2019

Data Capacity of Automotive Data CablingHow fast can we go?

2

PHY PHY

ChannelIC IC

cable, connectors

complexity, chip size, power consumption

material effort, process effort, complexity

EffortIC

Effort channel

Optimum

Total effort

⚫ Identify physical limits

⚫ Estimate maximum data rate

⚫ Consider robust system designand automotive requirements

⚫ Propose possible system solutionsfor data rates up to 25 Gbps

Calculation of Achievable Data Rates

3

Considerations:

⚫ Baseband signaling on0.14 mm² STP cabling

⚫ Channel transmission parameterReturn Loss, Insertion Loss

⚫ Environmental degradation

⚫ Electromagnetic emission limits

⚫ Electromagnetic immunity

⚫ PHY dependent transmission power limits, receiver noise, etc.

Shannon-Hartley theorem:(for White Gaussian Noise)

Channel Model Including EMI

4

ConnectorConnector

Connector

PHY

PHY

Tx Rx

Txupstream

PD Tx shaped

ILInsertion Loss S

N

PD Txupstream

EMI Emission Limit

EMI Disturbance(e.g. BCI Test Power)

TFIEMI Ingress

Transfer Function

PD NOther Noise

Sources

RLReturn Loss

TFEEMI Egress Transfer

FunctionTx P

ow

er

Shap

ing

Mas

k

PD Rx

Electromagnetic Interference (EMI)

Channel Capacity – Methodology (Example Only)

5

Cap

acit

yD

ensi

ty (

bit

/s/H

z)

Channel Data Capacity Results

6

Original STP link(0.14 mm², 15m Cable Length

Increased RL (-30dB) & 15m Cable Length

Increased RL (-30dB),reduced EMI (-15dB) &15m Cable Length

Increased RL (-30dB), reduced EMI (-15dB) & 11m Cable Length

Useable FrequencyBandwidth

Assumptions: • -125 dBm/Hz (Rx System

Noise)• 2 dBm TX Power

12.4 Gbps @ 15m

17.6 Gbps @ 11m

7

Channel Capacity Analysis – Conclusions

⚫ Data rates > 10 Gbps possible on single shielded pair

⚫ Improvements by increased return loss and shielding→ appropriate connectors and cables

⚫ Insertion loss is primary limiting parameter

⚫ Useable frequency bandwidth << 10 GHz

8

Channel Capacity AnalysisOptions for Robust 25+ Gbps Systems

⚫ Decreased insertion loss→ reduced length, improved STP/SPP → alternative media (e.g. coax)

⚫ Multiple number of Tx/Rx pairs→multi lane solutions should be investigated

⚫ Comparison with similar analysis from others would be important to confirm assumptions

Thank You!!!