Optical fiber solution for mobile fronthaul to achieve...

Optical fiber solution for mobile fronthaul to achieve Cloud Radio Access Network

Philippe CHANCLOU, Anna PIZZINAT, Fabien LE CLECH, To-Linh REEDEKER, Yannick LAGADEC, Fabienne SALIOU, Bertrand LE

ERMES

Session 9e, 04 July 2013 Future Network & MobileSummit 2013 Copyright 2013 ORANGE Labs

REEDEKER, Yannick LAGADEC, Fabienne SALIOU, Bertrand LE GUYADER, Laurent GUILLO, Qian DENIEL, Stephane GOSSELIN, Sy Dat LE, Thierno DIALLO, Romain BRENOT, Francois LELARGE, Lucia

MARAZZI, Paola PAROLARI, Mario MARTINELLI, Sean O’DULL, Simon Arega GEBREWOLD, David HILLERKUSS, Juerg LEUTHOLD, Giancarlo

GAVIOLI, Paola GALLI

ERMESEmbeddedResonant andModulablESelf-tuninglaser cavityfor nextgenerationaccessnetworktransmitter

contact: [email protected]

Summary:

� Context of Cloud Radio Access Network

� Which are the main constraints of fronthaul?

� Discussion on optical network for the fronthaul


� Self-seeded WDM solution

� Conclusion

coax

RRH

RRH

RRH

D-RoF

RRH

~15kg

Step 1: Macro base

station

Step 2: Distributed base

station with « traditional »

backhaul

Optical architecture for Mobile fronthaul:


RRU

RRU

RRU

Sys

tem

m

odul

ecoax

BBU

D-RoF

Sys

tem

m

odul

e

D-RoF

BBU

RRU: Remote Radio Unit

RRH: Remote Radio Head

BBU: BaseBand Unit

CSG: Cell-Site Gateway

D-RoF: Digital Radio over Fiber

(CPRI or OBSAI standard)

CSG

� RRH close to the antenna� Energy savings

� Space constraints in cell site cabinet

Step 3: BBU hostelling with stacking(or BBU centralisation)

• BBU colocalised in secured CO (no need for IPSec)

• X2 optimisation,

• Future proof with respect to LTE-A evolutions (CoMP support)

• Energy and deployment savings (expected 20%), site engineering

• Feasible today

-RRH RRH


opticaldistribution

network

RRH

RRH

RRH

RRH

RRH

RRH

IP/MPLS IP/MPLS IP/MPLS IP/MPLS

networknetworknetworknetwork

D-RoF

S1S1S1S1

X2X2X2X2

Central Office

BBU Sys

tem

m

odul

e

BBU Sys

tem

m

odul

e

BBUS

yste

m

mod

ule

MASG

FronthaulFronthaulFronthaulFronthaul BackhaulBackhaulBackhaulBackhaul

D-RoF

Step 4: C-RAN (or BBU hostelling with resource pooling)

RRH

RRH

RRH

Central

OfficeD-RoF

RRH

RRH

RRH

� Same advantages as step 3, plus

� Less interfaces to core network (S1 and X2)

� Simplification of mobility management

� CAPEX savings due to reduced BBU number

� Trials ongoing in other countries

-

4 Cs of C-RAN: Centralization, Cloud, Cooperation, Clean


opticaldistribution

networkRRH

RRH

RRH

IP/MPLS IP/MPLS IP/MPLS IP/MPLS

networknetworknetworknetwork

S1S1S1S1

X2X2X2X2

Office

BBU

Sys

tem

m

odul

e

D-RoF

Lo

adb

alan

cin

g

Fronthaulronthaulronthaulronthaul Backhaulackhaulackhaulackhaul

RRH might be replaced by Active Antenna Arrays (AAA): new antennas with integrated RRH

Definition of fronthaul and backhaul

RRH

RRH

RRH

IP/MPLS Digital-RoF X2

Central Office

EN


RRH

RRH

RRH

IP/MPLS network

Digital-RoF

S1

X2BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

MASGCE BIOM

fronthaul backhaul

EPC

EN

EN

Summary:






� Conclusion

Main constraints of fronthaul for optical network 1/2

typical fronthaul requirements

Data rate Symmetric bit rateMaximum BER 10-12

Multi-rate:CPRI1 = 614.4 Mbit/sOBSAI1 = 768 Mbit/sCPRI2 = 1228.8 Mbit/sOBSAI2 = 1536 Mbit/s


OBSAI2 = 1536 Mbit/sCPRI3 = 2457.6 Mbit/sCPRI4 & OBSAI3 = 3072.0 Mbit/sCPRI5 = 4915.2 Mbit/sCPRI6 &OBSAI4= 6144.0 Mbit/sCPRI7 = 9830.4 Mbit/s

Frequency accuracy +/- 2 ppb(NB. Time & phase synchronization is required for LTE-Advanced; A phase accuracy requirement budget will be allocated to the CPRI link )

Jitter Jitter values are specified according to CPRI requirements (v5.0 – 2011-09-21)

Main constraints of fronthaul for optical network 2/2

typical fronthaul requirements

Latency vs. reach LTE-A: 190µs round trip time (about 20km round trip)

Environment condition

RRH is an outdoor equipment (typ. -40 to +85°C)

Network operation Scope of responsibility (fiber and radio network)


Network operation Scope of responsibility (fiber and radio network)

Fronthaul : scope of responsibility

RRH

RRH

RRH

Central Office

BBU

Sys

tem

m

odul

e

demarcationpoint

demarcationpoint


RRH

RRH

RRH

BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

Fiber providerMobileoperator

Mobileoperator

Summary:






� Conclusion

Dedicated Fiber

CPRI

• no extra equipment cost for transmission

PRO’S

B&W* SFP

B&W* SFP B&W* SFP

RRH

Fiber Monitoringpassive part

RRH

RRH


BBU

• requires many fibers• extra equipment for fiber infrastructure

monitoring

CON’S

When PtP fibres is available

Optional fiber monitoring

B&W* SFPs

Fiber MonitoringActive part part

BBU

CWDM : passive solution

CWDM Fixedcolor SFP• few fibers

• No active components on passive mux • High MTBF• Suited for outdoor deployment

• Low cost point for CWDM technology (cf. RFP ONE)

PRO’SCWDM Fixed

color SFP

CWDM


RRHRRH

RRH

RRH


BBU

RFP ONE)• No introduction of transport latency• up to 16 channels per fiber

• inventory management required to align optic color with RRH-BBU link

• not bidirectional (2 fibers per link)• no native OAM

CON’S

passive devices

CWDM Fixedcolor SFPs

CWDM

CWDM

Fiber MonitoringActive part

passive part

BBU

DWDM : passive solution

Un-mapped trafficCPRIcolorless DWDM

• 44/88/96 channels per fiber• Bidirectional• No active components (passive mux)

PRO’S


BBU

CPRIcolorless DWDM

• No native OAM

CON’S

RRH

BBU

Fiber MonitoringActive part


Fronthaul : Infrastructure monitoring principle

Central Office

« Slave » passive box for demarcation point :- no touch of the traffic- optical attenuation ∼ 1 à 2 dB- monitor loopback- optical bandwidth : 1260 up to 1610 nm

« master » box offering:- add and drop of supervision wavelength (1630nm)- optical attenuation ∼1 to 3 dB- optical bandwidth : 1260 up to 1610 nm- deliver alarms and supervision indicators-Power monitoring : per line or per wavelength

1630nm


Tx Rx1630nm

passive active

Px1Px2

loop back for only 1630 nm

Summary:





� Self-seeded DWDM solution

� Conclusion

Fronthaul : CWDM solution

DeM

UX

MU

X

Central Office

Tx Rx

Monitoringwavelength

Px1Px2BBU

Sys

tem

m

odul

e

RRH


MU

XD

eMU

XPassive device offering filtering loop back

Active Equipment

BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

Fronthaul : DWDM fronthaul

Central Office

BBU

Sys

tem

m

odul

e

RRH

MU

X/

DeM

UX

� Automatic and passive assignment of the wavelength (colorless)

� Single fiber (bi-directional) architecture

Infrastrusture monitoringwavelength

&


BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

MU

X/D

eMU

X MU

X/D

eMU

X

?Passive device offering

filtering loop back

&channels monitor

Active Equipment

Fronthaul : DWDM fronthaul by self seeded (1/3)

Central Office

BBU

Sys

tem

m

odul

e

RRH

MU

X/

DeM

UX



RSOA (Tx)

PIN/APD (Rx)

Bid

i

SFP transceiver

RSO

A (

Tx)

PIN

/AP

D (

Rx)

Bidi


BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

MU

X/D

eMU

X

MU

X/D

eMU

X

PIN/APD (Rx)Bidi

self seeded source

Fronthaul : DWDM fronthaul by self seeded (2/3)

Central Office

BBU

Sys

tem

m

odul

e

RRH

MU

X/

DeM

UX



RSOA (Tx)

PIN/APD (Rx)

Bid

i

SFP transceiver

RSO

A (

Tx)

PIN

/AP

D (

Rx)

Bidi


BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

MU

X/D

eMU

X

MU

X/D

eMU

X

PIN/APD (Rx)Bidi

ASE source

Sliced ASE by AWGAmplified self-seeded source

Fronthaul : DWDM fronthaul by self seeded (3/3)Amplified Self Seeded

Central Office

BBU

Sys

tem

m

odul

e

RRH

MU

X/

DeM

UX


� Single fiber (bi-directional) architecture� standard WDM ODN

RSOA (Tx)

PIN/APD (Rx)

Bid

i

SFP transceiver

RSO

A (

Tx)

PIN

/AP

D (

Rx)

Bidi


BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

MU

X/D

eMU

X

MU

X/D

eMU

X

PIN/APD (Rx)Bidi

Amplified self seeded source

-8

-7

-6

-5

-4

-3

-2

Lo

g(B

ER

)

Sliced

Amplified

BER@10-3 with FEC

-50

-40

-30

-20

-10

0

Po

we

r (d

Bm

)

Amplified Self-Seeded

Sliced ASE

22dB

ASE

Fronthaul : DWDM fronthaul by self seeded2,5Gbit/s results


-12

-11

-10

-9

-8

0 2 4 6 8 10 12 14 16 18 20Feeder Optical budget (dB)

AmplifiedSelf-Seeded

• 19dB of feeder optical budget • Optical spectrum centered at 1533.7nm (CH9 of AWG)

• 22dB of optical improvement

ER=8dB

-90

-80

-70

-60

1531,5 1532,5 1533,5 1534,5 1535,5

Po

we

r (d

Bm

)

Wavelength (nm)

Impact on cavity length

-7

-6

-5

-4

-3

-2

log

(BE

R)

log(BER)= f(Received power)@2.5Gb/s

SS-10m

SS-5km


-12

-11

-10

-9

-8

-35 -30 -25 -20 -15 -10 -5

log

(BE

R)

Received power (dBm)

Self-seeded_10m-Cavity Self-seeded_5km-Cavity

SS-10m


-7

-6

-5

-4

-3

-2

log

(BE

R)

SS-10m

SS-5km

Amp-SS-5km-6

-5

-4

-3

-2

Lo

g(B

ER

)

SS

log(BER)= f(Received power)@2.5Gb/s log(BER)= (cavity length)@2.5Gb/s


-12

-11

-10

-9

-8

-35 -30 -25 -20 -15 -10 -5

log

(BE

R)



Amplified SS_10m-cavity Amplified SS_5km-cavity

SS-10m

Amp-SS-10m

-12

-11

-10

-9

-8

-7

0 5 10 15 20 25 30 35 40 45L

og

(BE

R)

Cavity length (km)


-7

-6

-5

-4

-3

-2

log

(BE

R)

ER=5.6dB

SS-10m

SS-5km

Amp-SS-5km-6

-5

-4

-3

-2

Lo

g(B

ER

) Amp-SS

SS



-12

-11

-10

-9

-8

-35 -30 -25 -20 -15 -10 -5

log

(BE

R)




ER=8dB

SS-10m

Amp-SS-10m

-12

-11

-10

-9

-8

-7

0 5 10 15 20 25 30 35 40 45L

og

(BE

R)

Cavity length (km)


-7

-6

-5

-4

-3

-2

log

(BE

R)

BER@10-3 with FEC

SS-10m

SS-5km

Amp-SS-5km-6

-5

-4

-3

-2

Lo

g(B

ER

)

SS

Amp-SS



-12

-11

-10

-9

-8

-35 -30 -25 -20 -15 -10 -5

log

(BE

R)




45km-long external cavity

SS-10m

Amp-SS-10m

-12

-11

-10

-9

-8

-7

0 5 10 15 20 25 30 35 40 45L

og

(BE

R)

Cavity length (km)

Conclusions

Expected gains from C-RAN

(most come from BBU

Hostelling)

- Radio Site engineering improvements (footprint reduced, energy efficiency, less operations on site..)- Radio performance improvements to be challenged with alternative solutions- Transport: leverage future-proof infrastructure and concentrate complexity at central office level


Technology short term possibilities

- CWDM: good, simple, cost effective option with additional “passive” fiber monitoring for first mile

Opticalarchitecture perspective

- Self seeded source allows to achieve a colorless DWDM source with- automatic and passive wavelength assignment- single fiber (bidirectional) link- athermal wavelength allocation

question: do we have solution up to 10Gbit/s?

Acknowlegment

ERMESEmbedded


ERMESEmbeddedResonant andModulablESelf-tuninglaser cavityfor nextgenerationaccessnetworktransmitter

FP7-ICT-2011-7

Fronthaul : Architecture of « passive » solution

RRH

RRH

RRH

Central Office

BBU

Sys

tem

m

odul

e

one link = 2 fibres

Automatic fibre protection

MU

XM

UX

path 1

path 2

stay


BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

BBU

Sys

tem

m

odul

e

RRH

RRH

RRH

MU

XMU

X

staypassive

Name Description Avail.#Fibers on

last mile

Synchro &latency

Integrated monitoring solution

Dedicated fibre

one fiber per RRH per techno

Short term

High Ok “Passive” (done by extra equipment)

Passive WDM

Colored SFP (RRH & BBU) cwdm or

dwdm

Short term for CWDM

Low

(2 to 4)Ok “Passive” (done by

extra equipment)

Fronthaul : short term vs mid/long term solutions


Active WDM

Typ. OTN based (CPRI

encapsulation)

Short term

Very low (1

to 2)

Ok (Freq. only)

Part of OTN

Passive + active WDM

Passive CWDM + OTN

Short term

Low

(2 to 4)TBC Passive + part of OTN

Synergy with FTTH

wdm // to gpon or integration in

NGPON2

Long term

FTTH infra reused

TBC PON OAM (OMCI)

CPRI overEthernet

CPRI I/Q encapsulated in

Ethernet

Long term

Medium to

HighTBC Ethernet OAM (MEF)

CPRI rate

RANGSM 1T1R

GSM 1T2R

WCDMA1T1R

WCDMA1T2R

LTE 10MHz

2x2

LTE 10MHz

4x2

LTE 20MHz

2x2

LTE 20MHz

4x2

CPRIData rate

12.304 Mbit/s

24.608 Mbit/s

307.2 Mbit/s 614.4 Mbit/s1228.8 Mbit/s

2457.6 Mbit/s

2457.6 Mbit/s

4915.2 Mbit/s

Calculation of data rate per CPRI link is based on the following expression:


Data rate = M x Sr x N x 2(I/Q) x 10/8

whereM is the number of antennas per sector (cf. multiple-input and multiple-output),Sr correspond to the sampling rate (sample/s/carrier),N is the sample width (bits/sample),2(I/Q) is a multiplication factor of two to account for in-phase (I) and quadrature-phase (Q) data,and a factor 10/8 in order to take account the 8B/10B coding.

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