Mobile Fronthaul – optical transport for C-RAN

architectures

Ingrid Nordmark

VP R&D Transmode

Forecasted monthly mobile data traffic

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Source: Cisco VNI mobile, Feb. 20141 Exabyte (EB) = 1000 million Gigabyte (10^18 Byte)

Trends/evolution of mobile transport networks

More capacity is needed in mobile transport networks

Macro cells become more dense

Small cells are introduced, enabling femto cells, in-building solutions,

WiFi etc

Multiple technologies, frequencies,

cell sizes and network architectures

are mixed

Het-Nets are being deployed

(mix of Small Cells, Macro Cells,

Femto Cells etc)

Mobile Fronthaul networks to

bridge distance between radio

and baseband unit

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Power and space – two issues that drive OPEX

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A cell site’s power consumption

represents the majority of a

mobile operator’s total power

consumption

OPEX (Power consumption,

OAM and space) represents

60% of TCO

Source: China Mobile

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Distributed base station architecture

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Remote Radio Head

(RRH) placed next

to antenna

Digital Radio over

Fiber (D-RoF) from

antenna to cell site

cabinet

RRU: Remote Radio Unit RRH: Remote Radio Head

BBU: Base Band Unit D-RoF: Digital Radio over fiber (CPRI/OBSAI)

Copper connected antenna Fiber connected antenna

Benefit:

Saves energy!

Remote Radio Head

(RRH) placed in cell

site cabinet

RRH

RRH

RRH

BBU

D-RoF

RRH

RRH BBU

Cell site cabinet Cell site cabinet

COAXRRH

Small cells would typically use a single RRH,

macro cell would use 3+ RRHs

Small cells would typically use a single RRH,

macro cell would use 3+ RRHs

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Implications on transport

Technology evolution enables use of

optical interfaces in cell site equipment

1. Allows distributed base station architecture

2. Allows centralized RAN (Radio Access

Network)

3. Allows Cloud RAN

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This opens up for WDM deployments

in mobile fronthaul networks

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Mobile Fronthaul and Mobile Backhaul

Mobile Fronthaul

“The connection between the two

main parts of a cellular base

station; the baseband unit and

radio unit”.

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RRH

RRH

RRH

IP MPLS

Network

CO

CO

CO

CO

BBU

BBU

Central Office

BBU

Mobile Fronthaul Mobile Backhaul

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Mobile Backhaul

“The network between the core

network and the sub networks at

the edge”.

Mobile Backhaul supporting multiple Radio Accesses

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Mobile Backhaul

RRH

RRHRRH

Mobile Fronthaul

Small cells

BBU

BBU

Macro cells

WiFi

Small cells

BBU

Radio Access Architectures (RAA)

Evolution of mobile transport networks

Today’s mobile networks are based on multi-layer

technology

Quality of the end user’s experience will rely on all

underlying technologies

Mobile networks are evolving

Backhaul IP MPLS

Network

Cell site cabinet

Cell site cabinet

CO

CO

Central Office

RRH

RRH

RRH

BBU

BBU

BBU

Fronthaul

Enlighten

Small cells

RRHRRH

RRH

RRH

RRH

RRH

IP MPLS

NetworkFronthaul / Backhaul

Central Office

BBU

BBU

BBU

RRH

RRH

RRH

RRH

RRH

RRH

RRH

RRH

RRH

A traditional mobile backhaul network

deployed for 3G/4G. Based on IP/MPLS

routers and Ethernet switches for last mile

access

The evolution of mobile networks,

centralization of radio basebands,

introduction of small cells requires a more

efficient transport. Mobile fronthaul and

mobile backhaul are separated

In near time the backhaul and fronthaul

networks will merge to one transport

network. Baseband pooling will be placed

closer to the mobile core network.

Introduction of SDN.

Backhaul

IP MPLS Core

RRH

RRH

RRH

RRHRRH

RRH

RRH

RRH

RRH

CSR

CSR

OSS 1 OSS 2

WDM, IP/MPLS

Cell site router

Cell site router

1

2

3

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Key requirements on Mobile Fronthaul

Low power and foot-print

Common Public Radio Interface – CPRI and

Open Base Station Architecture – OBSAI

Optical high speed protocols between RRH

and BBU

Low latency and sync performance are key in

mobile networks

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CPRI/OBSAICPRI rates OBSAI rates

10.1376 Gb/s

9.830 Gb/s

6.144 Gb/s 6.144 Gb/s

4.915 Gb/s

3.072 Gb/s 3.072 Gb/s

2.4576 Gb/s

1.2288 Gb/s 1.536 Gb/s

0.6144 Gb/s 0.768 Gb/s

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Orange labs has certified Transmode’s solutions

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RRHRRH

RRH

CO

-4 8

ch C

WD

M M

DU

1

2

3

4

5

7

6

8

+1

2457.6/1228.8 Mbps CPRI

2457.6/1228.8 Mbps CPRI

2457.6/1228.8 Mbps CPRI

Sync GbE

Sync GbE

BBU

Test demonstrated 2.458G CPRI together with Sync E

Fully sync transparent solution, tailored for the stringent latency and

sync requirements of CPRI

Latency measured to around 25 µs* (two sides)

Sync performance well below max value of RRH / BBU requirements

Line protection

BBU

MXPMXP

10G Multi-Service

Muxponder

10G Multi-Service

Muxponder

*Later tests with released

product indicates 8 µs

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Live test with MegaFon

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Test interoperability of Transmode CWDM 4 Gb/s SFP with NSN WCDMA

Flexi BTS BBU and RRH using OBSAI RP3 3.072 Gb/s interface

Results:

BTS is fully functioning with Transmode SFP

Phone calls performed successfully, including successful phone call with handover

to neighbouring 3G base station

Data transmission service test also performed successfully using mobile phone

registered in a demo sector

No alarms observed using NSN GUI interface on WCDMA Flexi BTS equipment

RRH MDU BBUMDU

OBSAI

3.072Gb/s

OBSAI

3.072Gb/sSFP SFP

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Passive Fronthaul WDM solution with colored RRH/BBU

interfaces

Semi Passive Fronthaul WDM solution with colored RRH/BBU

interfaces

Active units adding monitoring

capabilities

Active Fronthaul Transparent WDM Transponders

Framed WDM Muxponders

Customers require several different solutions

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Backhaul

CO

CO

CO

CO

Central

Office

Passive / Semi

passive fronthaul

Active

fronthaul

Central

Office

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THANK YOU!