LTE World Summit-Orange

8/18/2019 LTE World Summit-Orange

http://slidepdf.com/reader/full/lte-world-summit-orange 1/19

Fronthaul Challenges &

Opportunities Anna Pizzinat, Philippe Chanclou – Orange Labs Networks

LTE world summit 2014

Session : backhaul summit

23-25 June 2014, Amsterdam RAI, Netherlands



2

Contents

1. Cloud RAN Cloud RAN drivers

Local RAN

Centralized RAN

2. Fronthaul Fiber fronthaul and wireless fronthaul

3. Conclusion Centralize if you can, distribute if you must



Phase1 CRAN

BBU1

F i b r e

BBU2

F i b r e

Backhaul

Copper

M-Wave

Fibre

Backhaul

Copper

M-Wave

Fibre

Central Office

Radio

Site 1

BS

Radio

Site 2

BS

3 cells (1

site) per

BBU

3 cells (1

site) per

BBU

X2

Switching Layer

Backhaul

Copper

M-Wave

Fibre

Backhaul

Copper

M-Wave

Fibre

Backhaul

Copper

M-Wave

Fibre

Central Office

FutureCRAN

Possible future products

Fibre Fibre Fibre

BBU1 BBU2 BBU3

30 or

more cells

per BBU

30 or

more cells

per BBU

30 or

more cells

per BBU

Internal Internal

Phase 2 CRAN

Backhaul

Copper

M-Wave

Fibre

Backhaul

Copper

M-Wave

Fibre

Backhaul

Copper

M-Wave

Fibre

Central Office

BBU1 BBU2 BBU3

Fibre Fibre Fibre

Upto 30

cells perBBU

Upto 30

cells perBBU

Upto 30

cells perBBU

Internal Internal

Radio

BBU

BS

F i b r e

Site

Backhaul

Copper

M-Wave

Fibre

Remote Head

Site (RRU)

Radio

BBU

BS

C o - A x

Site

Backhaul

Copper

M-Wave

Fibre

Traditional

Site

Cloud-RAN compared to Distributed-RAN

Fibre between remote BBU and Radio head known as “Fronthaul” CRAN = Cloud RAN BBU = Base Band Unit BS = Base Station RRH = Remote Radio Head

Inter-site BBU pooling:30 - ?hundreds?

fronthaul links

Standard BS BBU Remoted BBU Centralised Intra BBU Pooling + CoMP Inter BBU Pooling + CoMP

Conventional Architecture Cloud RAN Architectures

Intra-site BBU pooling

(typ . 3 cells/sectors maxand several Mobile

Technologies: 2G, 3G,4G)

3 to 12 fronthaul links



4

C-RAN: centralized BBU

RRH

RRH

RRH

IP/MPLS

network

S1

Central Office

BBU S y s t e m

m o d u l e

BBU S y s t e m

m o d u l e

BBU S y s t e m

m o d u l e

Backhaul

Digital-RoF

Fronthaul : CPRI

Already deployed in some countries.

Today one BBU can already manage 6 RRH.

Next generation of BBU products will support multiple sites

(first level of pooling) and an internal interface to enable

CoMP support.CoMP=Coordinated MultiPoint

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

At research level: reach BBU pooling at user equipment (UE) level

C-RAN: intra & inter BBU pooling + CoMP

RRH → AAA,

Active Antenna Arrays

RRH

RRH

RRH

Wireless

Optical Fiber



5

Interest coming from network operational teams : site engineering

solution due to increased network rollout difficulties

Antenna site s impl ificat ion: footprint reduction, renting costreduction, reduced time to install

– Antennas sites with negotiation problems

– Adding new radio access technologies on existing sites with very

limited space

– Find new locations to replace sites that have to be switched off or

solution for failed negotiation sites – Reducing building cost (crane, metallic structure, etc.) and renting cost

– Reducing the electrical consumption, maintenance on site

– Less or not any cooling cabinets and shelters

– Decrease antenna site time to build and time to repair

Contribute to RAN strategies about

– Tower sharing

– Solar powered antenna site

– Simplification of operational installation procedures at antenna sites

C-RAN drivers

Drivers = cost reductions & ease of deployment



6

C-RAN drivers

Radio performances, very low latency between BBUs enables:

– Better performance in mobility

– Improved uplink coverage

– Higher capacity and improved cell edge performance with inter-site CoMP

When BBU’s are centralized (e.g. with C-RAN), it means pooling and aggregation

gains possible across a number of sites and energy efficient (see slide in annex)

C-RAN is future proof for LTE-A and beyond

In case of hetnets, higher interference is expected

– The same BBU shared between small cells and parent macrocell could provide evenhigher gains than in a macrocell scenario.

BBUs are in a secured location: no need for IPSec

The new fronthaul segment is the key to assess the TCO (total cost of ownership)

RRH

Central

Office

BBU S y s t e m

m o d u l e

RRH RRH

RRHRRH

RRH

RRH

RRH

RRH



7

How to build a fronthaul solution?

1. Technical requirements:

CPRI: digitized radio signal → high data rates

→ 3 sectors LTE 20MHz 2x2 MIMO → 3x2.457Gbit/s

→ Complete radio configuration LTE+ 3G+ 2G: up to 15 RRHs

Latency + synchronization + jitter also to be taken into account

2. Business aspects: low cost and scalability

3. Regulated countries: the fronthaul solution must be

available for other operators → wholesale offer

Fronthaul must be monitored to provide SLA

→ by dedicated fiber monitoring solution

→ different levels of SLA are possible

Antenna site demarcation point

→ outdoor compliant and as simple as possible

3. Non-Regulated countries:

fronthaul provided by the RAN vendor

technicalaspects

businessaspects

regulatoryaspects *

Optical fiber is needed for the fronthaul

Wireless fronthaul shall also be considered

RRH

RRH

RRH

CentralOffice

BBU

BBU

BBU

fiber / wireless provider Mobile operator

Mobile operator

demarcationpoint

demarcationpoint

Wireless

Optical Fiber

RRH

RRH

RRHdemarcation

point



8

Local C-RAN

RRU

RRU

RRU

coax

Cell s ite

cabinet

CSGBBU

Wirelessor

Optical Fiber

BBU

RRH

RRH

RRH

BBU

Wireless

or

Optical Fiber

BBU

RRH

RRH

RRH

Central

office

backhaul

Macro cellMicro/small cell

Micro/small cell



9

Wireless fronthaul: a reality today !

30 cm

BBU WFM WFM RRH

RRHDigital Interfaces

Ant enn a

Ant enn a

RF Interface

FrontLink™ 58 Product

RRH

Ant enn a

Wireless fronthaul on Orange commercial network with FrontLink™ solution from

Three sectors LTE 2600 MIMO 2x2 → 3x2.457Gbit/s CPRI on a wireless fronthaul link

→ In less than 70 MHz bandwidth



10

Wireless fronthaul: similar KPIs as fiber

Network accessibility

Network mobility

Network retainability

Fiber-based

FronthaulWireless Fronthaul Fiber-based Fronthaul Wireless Fronthaul

Fiber-based Fronthaul Wireless Fronthaul

Apple to apple comparison between f iber and wireless fronthaul over 3-months per iod



11

Wireless fronthaul: similar KPIs as fiber

Apple to apple comparison between f iber and wireless fronthaul over 3-months per iod

Network integrity

RTT ping 32 bytes RTT ping 1400 bytes



12

Wireless fronthaul enables local C-RAN

Remote

macro

sector

Macro site

« local C-RAN »

Remotemacro

sector

Remote

Micro sector

Macro site

Remote macro sector

Micro sector (3G and/or 4G)

Wireless Fronthaul

Remotre

Micro sector

Remote

Micro sector

With wireless fronthaul, turn existing macro site into local C-RAN

Easier and faster deployment, same network archi tecture, better radio performance



13

From local C-RAN to centralized RAN

Central

office

BBU

BBU

BBU

BBU

BBU

BBU

BBU

BBU

BBU

BBU

BBU

BBU

Fronthaul

BBUs

Stack

Mobile coverage

done by only RRHs



14

RRU: Remote Radio Unit RRH: Remote Radio Head

BBU: BaseBand Unit CSG: Cell-Site Gateway

D-RoF: Digital Radio over Fiber, CPRI or OBSAI

Optical

Distribution

Network

RRU

RRU

RRU

coax Cell site

cabinet

RRH

RRH

RRH

D-RoF

IP/MPLS

network

fibre

Central Office

CSG

Mobile Backhaul

(Carrier Ethernet, PON, MW)

fibreBBU

BBU

BBU

BBU

Mobile Fronthaul

RRH

RRH

RRH

D-RoF BBU

BBU

BBU

Dark fiber

RRH

RRH

RRH

D-RoF

BBU

BBU

BBU

Carrier Network

(Eth., OTN, PON)

Carrier fronthaul


Focus on fiber fronthaul

Demarcation

point

Demarcation

point

Wireless

RRH

RRH

RRH

BBU

Wireless

RRH

RRH

RRH

Not enough fiber available?Challenges: latency, jitter, synchronizationToo expensive for OTN

Local RAN

Centralised RAN



15

RRH

RRH

RRH

D-RoFBBU

BBU

BBU

Dark fiber

RRH

RRH

RRH

D-RoF

BBU

BBU

BBU

Carrier Network(Eth., OTN, PON)

• Native fronthaul solution

PRO’S

• Risk on performance (latency, synchro)

needed for CPRI• CPRI rate dependent

• Power supply required

• Foot print (cooling cabinet)

• Cost issue

CON’S

• Need fibers, lot of fibers

• No native monitoring and OAM

• High efficiency fiber sharing

• Native OAM and demarcation


Focus on fiber fronthaul

RRH

D-RoF

RRH RRH

BBU

BBU

BBU

Carrier fronthaul

Shared fiber

Passive WDM

low footprint

Active WDM:

- provide infrastructure monitoring and OAM- clear demarcation point

- CPRI transparent (no framing, bit rate independent)

- multiplexing low and high CPRI rate and other

traffics (alarm, GPS…)

- CWDM with colorized transceivers (outdoor

compatible) already available

- scalability to DWDM with colorless and outdoortransceivers under investigation



16

Conclusions and next steps

C-RAN drivers

and global

perspective

- Radio Site engineering solut ion (footprint reduced, energy

efficiency, less operations on site, etc.)

- Radio performance improvements and future proof for LTE-A

- Hybrid Fronthaul/Backhaul solution needed to address HetNets

- C-RAN to co-exist with regular RAN architecture- BBU in secured place and existing location

Fiber Fronthaul

- CWDM ready: good, simple, cost effective option with additional

“passive” fiber monitoring

- DWDM tomorrow with colorless transceivers and high number of

available wavelengths

Centralize if you can, distribute if you must

Wireless

Fronthaul

- Wireless fronthaul commercially available today (up to 7.3Gpbs):

enabling network densification and local C-RAN

- Use of millimetric bands in future for massive small cells (mRRU)

deployment (Nx10Gbps fronthaul links in dense urban areas)



17

Is it time to rethink CPRI?

Energy efficiency

- No sleep mode?

- Constant rate

Standardisation

-CPRI is coming from industry forums and not from a

standardization group (cf. ETSI Open Radio Innitiative)

-CPRI is defined as a “backplane extension” and not a network

interface

CPRI redefinit ion

- CPRI transport: include natively the OAM (Operations,

Administration and Maintenance) of the medium: Fiber, wireless,

etc…

- New function splitting interface to reduce bandwidth?

- Packetized fronthaul?

- Network archi tecture of Fronthaul (PtP, MPtoMP)- Reference configuration including demarcation point



merci



19

Calculation made on Rennes area France (one on 10 big cities)

– 15-km square coverage area,

– 86 cell sites, 13 intermediate central offices and one Core CO

Energy consumption gain

Based on average

consumption of

commercial

equipments

60

80

100

120

140

160

180

200

220

240

T o t a l E n e r g y C o n s u m p t i o n [ k W ]

PSVAC *

OTN

CSGW ˟

Optical transceiver

BBU

RRH

*PSVAC: Power Supplying, Ventilation and Air Conditioning˟CSGW: Cell Site GateWay

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