IEEE ICC’2015 London Panel on Mobile Fronthaul

Mobile Fronthaul Era- Are We There Yet?

Chair: Anthony Magee, 11th June 2015

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Agenda

• Introduction of the Panel and Setting the Scene

• ADVAs position on Mobile Fronthaul • Readiness today, research projects & challenges…

• Round Table – Panel member interests in Mobile Generally

• Questions and discussion section

• Summary & Wrap Up

© 2015 ADVA Optical Networking. All rights reserved. Confidential.3

Our Panel

• Chair: Anthony Magee, ADVA Optical Networking• Business Development Director

• Dr Chih-Lin I, China Mobile Research Institute,• Chief Scientist, Wireless Technologies

• Professor Andy Sutton, EE• Principal Network Architect

• Dr Nick Edwards, Openreach, part of BT Group• Wireless Strategy Manager

• Dr Nathan Gomes, University of Kent• Coordinating role for iCIRRUS, Technical Program Chair for IEEE ICC 2015

• Dr Volker Jungnickel, HHI• Head of the metro, access, and in-house systems group

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ADVA Solutions Overview

Automated service delivery and assurance from access to core

FSP Service Manager

Private Enterprise Networks

Data Center Connectivity

Carrier Infrastructure

Metro Core

FSP 3000

Broadband BackhaulMetro NetworksLong Haul

Carrier Ethernet Access

FSP 150

Mobile BackhaulBusiness EthernetEthernet Wholesale

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Mobile Backhaul Architecture

CE Access IP/MPLSMNO Core

BST CSGW NID Aggregation

• Mobile Backhaul• Carrier Ethernet

• Demarcation and Aggregation

• Timing Distribution

FSP 150 Family

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Mobile Fronthaul with Passive Monitoring

Non-intrusive fiber monitoring and optical service assurance

RRH

RRH

RRH

RRHRRHRRH

Small Cell Small Cell Small CellMacro Cell

FSP 3000ALM

FSPService Manager

• CWDM and DWDM filters with an upgrade port are ideally suited for the realization of linear add-drop structures

• Complimentary use of in-path OTDR, the complete link is monitored

• The add-drop filters function as demarcation points

Reflecta

nce

Nx Distance2x1x

BBU Pool

© 2015 ADVA Optical Networking. All rights reserved. Confidential.7

So Why a Panel on Fronthual?

• Mobile Network Evolution• CoMP, LTE-A, Small Cells, 5G• Leading many to look at and evaluate Fronthaul as an enabler

• Serious Concerns Arising from fronthaul• SLA Management• Latency• What architectures will/won’t work?• CPRI Capacity with 5G on the Horizon, what are the alternatives?• Mobile operators, carriers need to be convinced of technology and business case

• Answers need wide consultation and collaboration• ADVA collaborating via

• EU FP7 COMBO – Fixed Mobile Convergence• EU Horizon 2020 iCIRRUS – Ethernet as a basis for C-RAN transport• Interaction with standards bodies

• MEF, ITU-T, FSAN, IEEE 1904.3, IEEE 802.1 TSN

Industry Panel – a good way to gain insight and identify consensus

© 2015 ADVA Optical Networking. All rights reserved. Confidential.8

Introductions and Insights from the Panel

Andy SuttonPrincipal Network ArchitectEE Network Strategy11th June 2015

Mobile Fronthaul Era – Are We There Yet? – panel session:

A Mobile Network Operators Perspective

Contents

10

• Long-term UK market forecasts

• Current network architecture

• Local C-RAN

• Migration scenarios

• Summary

Long-term UK market forecasts

11

-

500

1,000

1,500

2,000

2,500

Dec-15 Dec-20 Dec-25 Dec-30Mo

nth

ly D

ata

Dem

an

d (

PB

)

E-mail/IM/Browsing/Download/MusicAugmented RealityMobile Gaming

0

2

4

6

8

10

12

14

16

18

20

0%

20%

40%

60%

80%

100%

2015 2020 2025 2030

Vid

eo

Data

rate

(M

bp

s)

Vid

eo

reso

luti

on

p

en

etr

ati

on

8K 4K HD SD Video Bitrate

-

200

400

600

800

Dec-15 Dec-20 Dec-25 Dec-30

Mo

nth

ly D

ata

D

em

an

d (

PB

)

Non-Video Data Demand

E-mail/IM/Browsing/Download/Music etc.Augmented RealityMobile Gaming Other services will emerge and drive

new revenue opportunities and

capacity challenges

Streaming and video resolution are key

drivers of long-term growth

22x

68% non-video

demand

2030 76%

DEMAND VIDEO

Current EE Network Architecture

12

Shared mobile backhaul network

Local C-RAN

13

M s

s

s

FronthaulTraditional backhaul M Macro cell s Small cell

Backhaul supports multi-RAT

macro and LTE small cells –

capacity, performance and

sync distribution

considerations

Operators

core

Baseband

capability

supports

macro and

small cells

Wired or

wireless

fronthaul

Local coordination between

macro and co-channel

small cells, support for

features such as dual-

attachment (HetNet CA?)

Combined backhaul and fronthaul requirementsExample use case – 3G MORAN, LTE site and backhaul share

14

FronthaulTraditional backhaul

GSM

MORAN

LTE#2

C

S

G

T

x

C

S

GT

x

All backhaul

Single op LTE C-RAN

All fronthaul*1 - Standalone or 2 x Multi-RAT base stations

LTE#1

GSM

MORAN

LTE#2

LTE#1

C

S

GT

x

Dual op LTE C-RAN GSM

MORAN

LTE#2

LTE#1

GSM

MORAN

LTE#2

T

x

All fronthaul*1

LTE#1

Examples only, not an exhaustive list of scenarios…

Summary

15

• Local C-RAN based on macro and its underlying small cells is an interesting architecture which seems to offer RAN capacity and/or performance benefits - remote sectors…

• The likelihood of a multi-RAT cell site having legacy services on backhaul while migrating LTE to C-RAN is probable and should therefore be supported in equipment

• There is a wide range of site and infrastructure sharing models which should be considered within the context of any network evolution; be this D-RAN, C-RAN or anything in between (in terms of functional split) - will today’s C-RAN scale for 5G?

• Different distributions of functionality will exist in different areas of a national network

• Cost of fronthaul is a significant barrier to adoption

THANK YOU

andy.sutton@ee.co.uk

Mobile Fronthaul Era –

Are We There Yet?

Nick Edwards

Wireless Strategy Manager, Openreach

Introduction to Openreach

• Openreach provides the UK

communications access network (the

“last mile”)

– 30 million residential customers

– served from >5500 exchanges

• via more than 500 communications

providers

• Since 2009, Openreach has been

building a new superfast broadband

coverage

– A layer 2 Ethernet product

– VDSL at up to 80Mbps

– Millions of km of new fibre

– A footprint of more than 22m UK homes

• Openreach also provides fibre Ethernet

circuits (typically 1Gbps symmetric)

– Used by businesses, education,

healthcare, etc

– The majority of mobile base stations

are connected via Openreach access Source: Ofcom infrastructure report 2014

Mobile backhaul

• Mobile backhaul is one of the most significant areas of business for Openreach Ethernet products. Recent developments include:

– Reduction of prices (approximately 50% reduction since 2013)

• A 1Gbps circuit today is a similar cost to a 100Mbps circuit in 2013

– Introduction of synchronised Ethernet for mobile backhaul

– A new VDSL street access product providing up to 80Mbps to a street location

– A new mobile infill product enabling a mobile operator to use a telegraph pole as a small cell site

• Telegraph poles provide a very large single estate of street sites mainly in suburban and rural areas

• Mobile operator requirements for cell site connectivity are evolving

– Ongoing roll-out of LTE macrocells – leveraging our ever growing fibre footprint

– LTE small cells – need low cost connectivity

– Evolution towards LTE Advanced/LTE TDD and in the longer term support of 5G

– Growing interest in options for mobile fronthaul

OPENREACHHANDOVER

POINT

EXISTING PCP

CopperMDF Exchange

Fibre

VDSL CABINET

• 1U space for CP backhaul

equipment

• 240V metered power

8U space for MNO

provided radio equipment

Copperpair

Openreach provided street cabinet stand

alone from existing PCP/NGA cabinet

Openreach provided antenna

RADIO CABINET

Co-axial cable

Fronthaul vs Backhaul

• Fronthaul can offer many benefits to mobile operators and end customers:

• Reduces site acquisition, installation, rental and maintenance costs

• Equipment footprint at the base station is reduced, simplifying plan and build

• Lowers energy consumption for electronics and air conditioning at the cell site

• Pooled baseband can be virtualised, reducing cost and simplifying signalling

• Provide best support for LTE Advanced enhancements to improve cell edge coverage and data rate requiring low latency, high bandwidth, tight synchronisation, e.g.

• Transmission from multiple base stations to one device (CoMP) and interference co-ordination

• However:

• LTE-FDD 2x20MHz has 150Mbps peak rate, but CPRI needs 2.5Gbps/sector

• CPRI is independent of loading so does not benefit from statistical multiplexing

• CPRI bandwidth scales linearly with number of sectors, antennas, channel bandwidth

• Estimates of backhaul requirement for a 5G site may be in excess of 500Gbps

• Each sector needs separate fibre or wavelength

• Daisy chain possible but introduces new point of failure

• Very tight timing requirements make transport of CPRI over Ethernet impractical:

• Latency <100μs round trip, +/- 30ns imbalance

How could Fronthaul be realised?

CPRI fronthaul for macrocells

Would require solutions for efficient use of fibre, e.g. Wavelength Division Multiplexing (WDM)

Openreach is working closely with mobile operators

– Recent lab demonstration of CPRI fronthaul

Baseband

Radio head

Router

Remote

site

4

G

4

G4

G4

G3

G

3

G3

G3

G

Example: WDM with a 4-way split

3 sectors of 4G fronthaul

Ethernet for management+3G/2G

WDM

CPRI fronthaul for small cells

Economics are still very challenging even for conventional Ethernet backhauled small cells

– Fronthauled small cells are even more challenging

New base station architectures providing efficient fronthaul/midhaul would be essential to support 5G bandwidths

– Fronthaul over Ethernet would enable existing high volume Ethernet connectivity to be used

– Maximises benefits of virtualisation of the baseband functions

iCIRRUS- concept

Key: intelligence placed

in fronthaul of C-RAN

http://www.icirrus-5gnet.eu/ http://www.intelligent-nirvana.net/

Added intelligence for

D2D and hetnet

operation

Centralised functions

available to mobile

cloud processing

D2D, mm-wave, mobile

cloud important for 5G

What sort of Ethernet links?

• Ethernet over CPRI? Only real advantage is provision of OAM

• CPRI over Ethernet? Possible

Loss of synchronism through Ethernet switches

Additional framing overhead

• Sample waveform placed directly in Ethernet

frames New standards required

Loss of synchronism

• Bit-rate/bandwidth requirements

BBU pool to RRH connection through switches

Low-latency switching required: Cut-through operation

No contention/queuing

Bit-rate requirements: current and projected

Current CPRI/ORI interfaces Projected requirements

Line rate Example Use Possible uses Approx. line rate*

614.4 Mb/s 10 MHz LTE

channel, with

8B10B encoding

100 MHz, 8

antennas

(sectors/MIMO/C

oMP)

28 Gb/s

4.9152 Gb/s 8 x 10MHz

(multiple

antennas,

8B10B)

500 MHz, 8

antennas

(sectors/MIMO/C

oMP)

141 Gb/s

10.1376 Gb/s 10 x 20 MHz

(multiple

antennas,

64B66B)

500 MHz, 16x8

massive MIMO

2.25 Tb/s

Fronthaul/”fronthaul lite” division

Bandwidth

requirements

may be reduced,

but latency may

become a more

significant

problem

“Fronthaul lite” advantages and challenges

View, Master, Slide Master to change this text to the title of your presentationPage 27

Apart from bit-rate reduction…

Single streams instead of multiple streams for each antenna possible –

weights sent to antenna units/RRHs

Burst-like user data really enables statistical multiplexing gains

CSI sharing for multi-antenna (multi-RRH) techniques needs to take into

account delays

Tight synchronisation will still be a problem, may be even more so

Analogue radio over fibre

Simplest antenna

unit.

Lowest latency in

fibre links?

Lowest energy

consumption?

Performance degradation for high-bandwidth, high-frequency links

- research needed to obtain required/improve/enhance performance

Component costs if not a ubiquitous technology

- integration, photonic integration

Acknowledgments to current projects

Use of Ethernet in the fronthaul

• Use of commodity equipment, or at least lower-cost, industry-standard

equipment

• Sharing of equipment with fixed access networks, enabling greater

convergence and cost reductions

• Ethernet OAM functions standardised

• Use of switches/routers to enable statistical multiplexing gains and lower

the aggregate bit-rate requirements of some links

• Use of standard IP/Ethernet network switching/routing functionality,

including moves to functional virtualisation and overall network

orchestration

• Monitoring through compatible hardware probes.

Fibre transport/C-RANs: bandwidth problem

• Digitised transport preferred:

• 100 MHz bandwidth, 12 bits per sample for OFDM (?), > 2.4 Gb/s per signal

• MIMO/virtual MIMO – multiple signals N x 2.5 Gb/s?

• 1 GHz + bandwidth wireless signals (5G) – 100 Gb/s links to remote radio

heads?

• Compression possible – but only 2 (lossless) or 3 times reduction (China

Mobile)

• Baseband transport

• Order of magnitude reduction in bit-rates

• Co-operation/coordinated transmission?

• Analogue transport (radio over fibre)

• Performance?

“Fronthaul lite” as part of X-haul

Courtesy of Philippe Chanclou, Orange

Labs, OFC 2015, panel presentation

NEW FUNCTIONAL SPLIT

Volker Jungnickel, Luz Fernandez del Rosal

Fraunhofer Heinrich Hertz Institute, Berlin, Germany

Future RAN implementation

• Centralized Radio Access Network (C-RAN)

Fully centralized baseband unit (BBU)

All transport is fronthaul

For operators with own fiber infrastructure

• Distributed Radio Access Network (D-RAN)

Idea is to minimize transport overhead and latency

Data and control are shared among BBUs

Fully distributed processing

For operators with leased infrastructure

• The solution might be between these two extremes

iCirrus proposes Ethernet-based „Fronthaul Lite“

Minimize transport, maximize flexibility

Using new „functional split“ discussed in recent literature

Flexible functional split?References: 35-

38

Figure from P. Rost et al. “Cloud technologies for flexible 5G

radio access networks”, IEEE Communicatinos Magazine,

Vol. 52, No. 5, pp. 68-76

• Old functional split

Digital radio-over-fiber between PHY

and RF

CPRI/ORI: Sampled waveform transport

Huge data rates: No compression, no

statistical multiplexing

• New functional split

Find the right balance between C- and

D-RAN

Compress fronthaul signals more

efficiently

Enable statistical multiplexing

Minimize the added latency

Proposed fixed split is between PHY

and MAC

More intelligence into the remote radio

head

Literature review on

compression (I)Old functional split

New functional

split

Point-to-point (P2P)

DistributedTime-domain Frequency-domain

Fixed Dynamic Fixed Dynamic

Charact

.

Fixed BW

(bandwidth)

reduction

Several

methods

Transmission of

used BW

Adaptive multi-

rate filter

CP & guard

band removal

& several

methods

Transmission of

used BW

Joint processing

of signals

from/to multiple

RRHs

Time-domain

Several

methods

New functional split

between BBU and

RRH

Pros

Statistical

multiplexing

Lossless?

Statistical

multiplexing

Optimal

performance in

network

topologies

Lossless

Statistical

multiplexing

Spatial

compression

Waveform

independent

Cons

Lossy

No statistical

multiplexing

Lossy Lossy

DSP

Redundancy

No statistical

multiplexing

DSP

Redundancy

Lossy

DSP Complexity

No statistical

multiplexing

New architecture

and challenges

Refs 1-10 11-15 16-19 - 20-31 32-41

Compression Methods Overview (II)

Old funtional splitting

New

functional

splitting

Point-to-point (P2P)

DistributedTime-domain Frequency-domain

Fixed Dynamic FixedDynami

c

Compressio

n

ratio (ref)

28.57% (4)

28.08% (9)

Average

37.5%(13)

4% @ QPSK(16)

15% @

64QAM(16)

- Not available 3% @ 10% load(32)

16.6% @ 50%

load(32)

33.3% @ 100%

load(32)

EVM (ref) 2% (4)

1.89% (9)

Average <

1%(13)

< 0.025%(16) - Not available Lossless(32)

Validation (ref)

Real-time (1,2,5,9)

implementation

Real-time(13,15)

implementation

Simulation - Simulation Simulation

Ref 1-10 11-15 16-19 - 20-31 32-41• Proposed new split enables lossless compression w/o added

latency

• Compression ratio depends on served traffic: Statistical Multiplexing

• Independent on the waveform, i.e. applicable to TDMA, CDMA,

OFDMA, 5G

New Functional Split (SISO)

Base station is decomposed into most important blocks

• MAC processor (scheduler) and PHY processor

New functional split lies between PHY and MAC (orange line)

• Downlink: Hard bits for transport blocks plus ressource-map information

• Uplink: Hard bits plus soft bits for transport block plus user ID

Same incl. (massive)

MIMO

The beamformer for (massive) MIMO is shifted into the RRH as well Limit the transport to the number of streams actually used, not antennas

Same incl. MIMO and

CoMP

CoMP and MIMO make the picture complete Downlink data are exchanged over X2++ with adjacent cells (same as in EASY-C

implementation)

Uplink FFT outputs may be exchanged over X2++ with adjacent cells

Small cells are implemented same as macro-cells

Conclusions

• New functional split shifts the fronthaul from below-PHY to below-MAC

• All PHY functions are at the remote radio head

• All MAC functions are in the central office

• Best compression ratio is achieved depending on the traffic load

• Full statistical multiplexing gain: Only scheduled data are transported

• Basic ideas were already discussed in the literature

• Implementation is the next challenge

• The basic principle is independent on the waveform

• Ethernet-based transport is suggested for flexible deployment

• Need for efficient synchronization solutions, e.g. using 1588 PTP and

SynchE

Thank You

IMPORTANT NOTICE

The content of this presentation is strictly confidential. ADVA Optical Networking is the exclusive owner or licensee of the content, material, and information in this presentation. Any reproduction, publication or reprint, in whole or in part, is strictly prohibited.

The information in this presentation may not be accurate, complete or up to date, and is provided without warranties or representations of any kind, either express or implied. ADVA Optical Networking shall not be responsible for and disclaims any liability for any loss or damages, including without limitation, direct, indirect, incidental, consequential and special damages, alleged to have been caused by or in connection with using and/or relying on the information contained in this presentation.

Copyright © for the entire content of this presentation: ADVA Optical Networking.

Some aspects of the work leading to this panel have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 644526 (iCIRRUS) and were supported by the European Commission under the Seventh Framework Programme (FP7) by the project COMBO (under grant agreement n° 317762)