Improving energy efficiency in passive optical networks with … · 2012-06-20 · Improving energy...

Improving energy efficiency in passive optical networks

with service guarantees

L. Valcarenghi1, M. Chincoli2, P. Monti2, L. Wosinska2, Neelakandan Manihatty Bojan1,

D. Pham Van1, P. Castoldi1

TeCIP Institute, Scuola Superiore Sant’Anna, PisaONLab, KTH, Kista, Sweden

ETSI Workshop on Energy EfficiencyJune 20-21, 2012, Genoa, Italy

© 2012 Scuola Superiore Sant’Anna2

Summary

• Energy consumption in optical access

networks overview

– Classification of methods to reduce optical access

network energy consumption

– Standard body initiatives to reduce energy

consumption in optical access networks

• Current activities at TeCIP Institute

– Service based variable sleep period

– Energy efficient PON testbed

• Conclusions


Energy Efficient Light Bulbs and Passive Optical Networks

~20 W

(~100 W traditional light bulb

tungsten filament lamps)

Energy Efficient Light bulb

(Compact fluorescent bulbs)

Gigabit Ethernet

Optical Network Unit (ONU)

~10 W

6 hours/day →

120 Wh/day

24 hours/day →

240 Wh/day


Energy Consumption in Communications Networks

• Except home networks, access networks, together with mobile radio networks, are the major contributorsto energy consumption in communications networks

– Because of the high number of Customer Premises Equipments (CPE)

– Because of the bandwidthunderutilization

Remaining part home networks

Source: C. Lange, D.

Kosiankowski, R. Weidmann, and

A. Gladisch, “Energy Consumption

of telecommunication networks

and related improvement

options”, IEEE JSTQE,

March/April, 2011

Access=Fixed Access Network=

Fiber to the Exchange (FTTE) and

Fiber to the Cabinet (FTTC): fiber

+ xDSL; FTTH (PON)

Wired NetworksAccess 80%


Approaches for implementing energy efficiency in

PONs

• Physical layer solutions target physical layer of PON architectures without modifying the upper layer protocols

– Device-oriented solutions reduce energy consumption of physical devices

– Service-oriented solutions improve the performance of the services provided by the physical layer to enable upper layer solutions

• Data Link solutions target the data link layer of the IEEE 802.3 architecture (i.e., the MAC layer) or the Transmission Convergence (TC) layer in GPON

– Based on the possibility of switching network elements to a low power mode (e.g., sleep mode)

• Hybrid solutions are the ones that combine physical and data link layer solutions to reduce

energy consumption (e.g., sleep mode and adaptive link rate).

Source: L. Valcarenghi, D. Pham

Van, P. Castoldi, “How to Save

Energy in Passive Optical

Networks”, Invited paper, ICTON

2011

Source: Shing-Wa Wong, L.

Valcarenghi, She-Hwa Yen, D.R.

Campelo, S. Yamashita, L.

Kazovsky, “Sleep Mode for

Energy Saving PONs: Advantages

and Drawbacks”, GrennComm2,

IEEE Globecom 2009 Workshops


ImpactFonte: EUROPEAN COMMISSION DIRECTORATE-GENERAL JRC JOINT RESEARCH CENTRE Institute for the Energy, Renewable Energy Unit, “Code of Conduct on Energy Consumption of Broadband Equipment Version 4”, 10 February 2011

IdleWorking

Physical Approach

Data Link

Approach

Pav

PON

POFF

t

Instantaneous power

Average power

0.45820.1659.7

Carbon

Emission

Factor (kg

CO2e/kW

h)

Electrical

power

price Italy

(EUR/kWh)

Average

Power

ONU with EE

(W)

Average Power

ONU without EE

(W)

~6k~1200.020

CO2e emissions

(t CO2e)

(with EE)

~12k~2000.039

CO2e emissions

(t CO2e)

(without EE)

~ 2M~42k7.008

Electrical bill

(EUR/year) (with

EE)

~ 4M~81k14

Electrical bill

(EUR/anno)

(without EE)

~13k~2600.044Energy (MWh/year)

(with EE)

~25k~5000.085Energy (MWh/year)

(without EE)

30162160001

Number of ONUs

12.5%

23%


Evolution of energy saving in PONs in the Standards

• ITU-T G.Sup45 “GPON power conservation”

• ITU-T G.987.3

• ITU-T G.988 (clause “9.1.14 ONU dynamic power

management control”)

• IEEE 802.3az “Energy Efficient Ethernet”


Considered Scenario

ONU-2

Passive Splitter

Central Office

Idle traffic, butactive receivers and

service lines

ONU-1

OLT

ONU-N

Differential reaches

ONU1

ONU2

ONUn


Energy Efficient PONs: When, Where and How ?

• Questions

– When to utilize sleep techniques ?

– What are the key parameters that affect PON

power savings ?

– How do they are related ?

– Where should we intervene to improve the

power efficiency?

– Which are the drawbacks ?


Service based variable sleep period: approach rationale

• Two main decisions must be made in data link layer approaches

– When to sleep

– For how long

• Reduce ONU energy consumption

– By means of service-based variable sleep period

• initially proposed by R. Kubo, J.-I. Kani, Y. Fujimoto, N. Yoshimoto, and K. Kumozaki,

“Adaptive Power Saving Mechanism for 10 Gigabit Class PON Systems,” IEICE

Transactions on Communications, vol. 2, no. E93.B, pp. 280–288, 2010

• Guarantee delay constraints to applications subscribed by ONU end-users

– By computing the maximum allowed sleep time based on subscribed services and

queueing theory system model

•“End-user multimedia QoS

categories,” ITU-T Recommendation

G.1010, nov. 2001.

•“Network performance objectives

for IP-based services,” ITU-T

Recommendation Y.1541, Dec. 2011.

• “Ethernet frame transfer and

availability performance,” ITU-T

Recommendation Y.1563, Jan. 2009.

IPTD=IP packet Transfer Delay; IPDV=IP packet Delay Variation


ONU OLT

Request (T=Ts)

ACK

Confirmation

DATA

Request (T=Ts)

Activemode

Sleepmode

DATA

Activemode

Activemode

RequestOLT informs the ONU to sleep

for a time Tsl

ACK ONU replies to a Requestmessage

Confirmation

Ts choice

Interarrival-basedapproach

Two modes for sleepand wake-up periods

Three control messages

service-based

approach

OVERVIEW

ONU informs the OLT aboutthe end of the sleep mode and check the presence of

downstream traffic

Request (Ts=0)

ACK

Sleep and Periodic Wake-up (SPW)


e.s.c.(exponentialsmoothingcalculation)

ONU OLT

Request (T=Tsl)

ACK

Confirmation

Request (T=0)

Activemode

Sleepmode

Activemode

Activemode

i> i th

i< i th

DATA

Tsl is a constant value

( ) 11 1 −− ⋅−⋅ ka,kka, ir+ir=i

In the Request message the time T is set between two values

if

T = Tsl

T = 0 ia,k < ith

ia,k >= ith SPWenabled

SPWdisabled

Parameter Variable

Average inter arrival time at k time

ia,k

Threshold ith

Smoothing factor r

ACK

[1] R. Kubo, J.-i. Kani, H. Ujikawa, T. Sakamoto, Y. Fujimoto, N. Yoshimoto, and H. Hadama, “Study

and demonstration of sleep and adaptive link rate control mechanisms for energy efficient 10G-EPON,”

Optical Communications and Networking,IEEE/OSA Journal of, vol. 2, no. 9, pp. 716 –729, september

2010.

Interarrival-Based Approach[1]


The OLT is costantlyaware of the servicessubscribed to each

ONU

For each QoS class a specific sleepperiod is assigned to maximize the

energy efficiency while guaranteeingthe constraints

Tsl is a function of the delay constraints

The OLT has a table in which servicesare categorized in terms of QoS class

with specific bandwidth and delayconstraints

The OLT builds a table containing the IPTD, IPDV, and minimum bandwidthrequirement per each registered ONU

Each ONU issubscribed to a list of

services

Service-based Approach Rationale


ServiceSubscription

Update IPTD(min IPTD) Ts = 2*IPTD - TOH - RTT

Inform ONUTsl

( )( ) ( )Sλ

Sλ+

Sλ

Sλ+V+

V

VV=Wq ⋅−⋅

⋅⋅−⋅⋅⋅

⋅−

1212

1

2

222

POLLING SYSTEM WITH GATED SERVICE

POLICY WITH IDENTICAL STATIONS

22RTT+T+T

=V

W OHslq ≈

2V

Wq ≈

RTT+T+T=V OHsl

Queuing delay

V Vacation time=Idlle time

S Service time

N Number of stations

Service-based Variable Sleep Period

Modified SPW with service-based variable sleep period

IPTDWq ≤qW


Parameter Variable Value

Overhead time TOH 2ms

Round-trip time RTT 0.4ms

Power consumption in sleep mode Psl 1 W

Power consumption in active mode Pa 10 W

Frame size fs 1250 B

Transmission rate 10 Gb/s

Simulation Scenario Service-based Approach

• One OLT

• One ONU

• Different QoS class mix


Results


Remarks

• Implemented a modified service-based

variable sleep period

• Guarantee IPTD while maximizing the energy

efficiency at ONUs

• Method successfully exploits the acceptable

delay to maximize the ONU sleep duration


OLT Board

Stratix IV GT

TX Design

Packet Generator

10GbE MAC

10GBASE-R

PCS PMAPacket

Checker

10GbE MAC

10GBASE-R

PCS PMA

SMA Cable

SLEEP

LOW

POWER IDLE

IDLE

ACTIVE

WAKE

ONU Board

Stratix IV GT

RX Design

Green FSM

Downstream Transmission

Green PON Testbed


Testbed Setup


OLT and ONU


Conclusions

• Energy consumption in optical access

networks

• Current research ongoing at Scuola Superiore

Sant’Anna TeCIP

– Service-based variable sleep time

• Energy consumption reduction while providing delay

guarantees

– Green PON testbed

• Initial results from OLT-ONU board to board

communication


Bibliography

• S.-W. Wong, L. Valcarenghi, S.-H. Yen, D. Campelo, S. Yamashita, L. Kazovsky, "Sleep Mode for Energy Saving PONs: Advantages and Drawbacks Drawbacks," IEEE 2nd International Workshop on Green Communications (GreenComm), 2009, Honolulu, HI, USA [Best Paper Award]

• L. Valcarenghi, M. Presi, G. Contestabile, E. Ciaramella, P. Castoldi, “Impact of Modulation Formats on ONU Energy Saving”, Proc. of Ecoc2010

• L. Valcarenghi, D. Pham Van, P. Castoldi, “How to Save Energy in Passive Optical Networks”, Invited paper, ICTON 2011

• L. Valcarenghi, D. R. Campelo, Shing-Wa Wong, She-Hwa Yen, S. Yamashita, D. Pham Van, P. G. Raponi, P. Castoldi, and L.G. Kazovsky, “Energy Efficiency in Passive Optical Networks: Where, When, and How ?”, accepted for publication IEEE Network 2012

• L. Valcarenghi, D. Pham Van, M. Chincoli, P. Monti, L. Wosinska, P. Castoldi, “Energy Efficient PONs with Service Delay Guarantees”Submitted for publication SustainIT 2012

• L. Valcarenghi and P. Castoldi, “Impact of unicast and multicast traffic on ONU energy savings”, invited paper ICTON 2012


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