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1 | © 2016 Infinera

Mobile Backhaul / FronthaulTechnology Overview

Andres MaderoDirector, Service Provider Architecture


Mobile Network Evolution


Evolution of Mobile Networks (3GPP)

Key Additions in LTE-A• EICIC

• Coordinated Multi-point

• 20MHz to 100Mhz

• Increased user throughput up to 1Gbps

• Self Organizing Networks Improved (SON)

• Heterogeneous Networks (HetNet)

• Relay Nodes

• Beamforming and higher order MIMO

• Carrier Aggregation

2G/GSM

UMTSGERAN U-TRAN

eU-TRAN

GERAN = GSM/Edge RAN, UTRAN = UMTS Terrestrial RAN, eUTRAN = Evolved


Evolution of Backhaul Networks

Started as ATM, IP became an alternative in

R5

ATM Backhaul Only All IP Backhaul

2G/GSM

Right now there is no anticipated migration of backhaul to anything else


Trends/evolution of mobile transport networks

More capacity is needed in mobile transport networks

Fiber is becoming the media for mobile transport networks

• Macro cells become more dense

• Small cells are introduced

• Multiple technologies, frequencies, cell sizes and network architectures are mixed

− LTE-Advanced address multi-antenna techniques

• Het-Nets are being deployed

• Mobile Fronthaul networks to bridge distance between antenna and base station


WDM is the preferred C-RAN technology from 2018 and beyond

• 33,86% CAGR - 2016-2030

Dedicated fiber is dropping off

Ethernet is starting to win traction around 2020

WDM is growing to be the preferred C-RAN technology

Source: SNS Research, 2016


LTE attracts new applications and revenue streams

The low latency requirement in LTE networks attracts development of new applications requiring real-time treatment

• 4G/LTE is now about half lag time as HSDPA

• Government, healthcare and other markets and industries are attracted to mobile networks

• Examples: Real-time video surveillance, distance learning, expanded telemedicine, public safety

Source: Backhaul Forum 2014

Comparing lag timesof the mobile network standards


Latency performance for LTE compared to latency for 5G


5G technology requirements

Requirements are driven by the internet of things 1-10Gbps connections to end points in the field 1 millisecond end-to-end round trip delay (latency) 1000x bandwidth per unit area 10-100x number of connected devices (Perception of) 99.999% availability (Perception of) 100% coverage 90% reduction in network energy usage Up to ten year battery life for low power, machine-type devices


With 5G It all becomes about latency and bandwidth

Source: Ericsson


Mobile BackhaulKey Components


Trends in mobile networks impact mobile backhaul

Strong need to enhance and improve existing mobile backhaul

To fulfill capacity requirements, new technologies are required

More stringent accuracy requirements needed to support new functionality, like LTE coordinated multipoint (CoMP) and enhanced inter-cell interference coordination (eICIC)

• Synchronization becoming one of the most important criteria

• Phase and time synchronization is required for LTE-Advanced

SLA assurance and end-to-end performanceis important

Support for multiple radio access architectures (RAA)


Evolution to Fronthaul Architectures

Everything at the

Antenna

Move to BBU Hotels

BBU Collaboration

C-RAN

Virtualization

Radio Equipment Evolution

Network Architecture Evolution

C-RAN


So What does the overall architecture look like?

RRH: Remote Radio HeadBBU: Base Band UnitD-RoF: Digital Radio over fiber (CPRI/OBSAI)

Cell sitecabinet

RRH

RRH

RRH

RRH

RRH

RRH

D-RoFFronthaul Backhaul IP MPLS Network

Stacking of BBUsin Central Office

CO

CO

CO

COBBU

Central Office

RRH

RRH

RRH

Fiber all the way from antenna to Central Office

Cell sitecabinet

Cell sitecabinet

BENEFITS: Increased security of CO

Saves space in the cell site

Lower total OPEX

Enables X2 optimization

Supports LTE-A evolution

Less interfaces to backhaul / core

CAPEX saving due to lower number of BBUs

Simplification of mobility management

Load

bal

anci

ng

Source: GSMA


1. Distributed base station architecture

RRU: Remote Radio Unit RRH: Remote Radio Head

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

Remote Radio Head

(RRH) placed next to

antenna

Digital Radio over Fiber

(D-RoF) from antenna to

cell site cabinet

Copper connected antenna Fiber connected antenna

Remote Radio Unit

(RRU) placed in

cell site cabinet

RRH

RRH

RRH

BBU

D-RoF

RRU

RRU BBU

Cell site cabinet Cell site cabinet

COAX

Central

Office (CO)

RRU

Small cells would typically use a single RRU,

macro cell would use 3+ RRUs

Small cells would typically use a single RRH,

macro cell would use 3+ RRHs

Benefit: Saves energy!


2. BBU centralization – Centralized-RAN (today)

Additional Benefits:

Saves even more energy!

Increased security of CO (no need for IPSec)


Lower total OPEX



RRU: Remote Radio Unit RRH: Remote Radio HeadBBU: Base Band UnitD-RoF: Digital Radio over fiber (CPRI/OBSAI)

RRH

RRH

RRH


Cell site cabinet

Cell site cabinet

Cell site cabinet

Fiber all the way from antenna to Central Office Stacking of BBUs in Central Office

CO

CO

CO

COBBU

BBU

Central Office

BBU

RRH

RRH

RRH

RRH

RRH

RRH


3. BBU Consolidation – Cloud-RAN (Future)

RRH: Remote Radio HeadBBU: Base Band UnitD-RoF: Digital Radio over fiber (CPRI/OBSAI)

Cell sitecabinet

RRH

RRH

RRH

RRH

RRH

RRH


Stacking of BBUsin Central Office

CO

CO

CO

COBBU

Central Office

RRH

RRH

RRH

Fiber all the way from antenna to Central Office

Cell sitecabinet

Cell sitecabinet

BENEFITS: Saves even more energy!

Increased security of CO (no need for IPSec)


Lower total OPEX



Less interfaces to backhaul / core

CAPEX saving due to lower number of BBUs

Simplification of mobility management

Load

bal

anci

ng

RRHRRH

RRH


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

• Technology shift paves way for more efficient transport

A traditional mobile backhaul network deployed for 3G/4G. Based on IP/MPLS routers and Ethernet switches for last mile access.

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

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.

2

Backhaul IP MPLS Network

Cell site cabinet

Cell site cabinet

CO

CO

Central Office

RRH

RRH

RRH

BBU

BBU

BBU

Fronthaul

Small cells

RRHRRH

RRH

RRH

RRH

RRH


Key Components and Interfaces of an LTE Network

ENodeB - Base Station - Smarter than a NodeB in 3G architecture, eliminates the need for a RNC

S1 Interface – User plane and control pane data

X2 Interface – Communication and coordination between eNodeBs. (3-5% of S1 Interface)

UE - Handset

MME – Main Control Node. Plays a role in user authentication, handoffs, and initial connection setup (PGW and SGW), Location, Bearer Management

SGW – Serving Gateway. Terminates the EUTRAN – Each UE has 1. Responsible for handovers, packet routing and forwarding, accounting

PGW – Packet Gateway Node. UE has 1 per PDN connection. Provides UE IP address allocation (DHCP), QOS, , packet filtering per UE, etc.

http://upload.wikimedia.org/wikipedia/commons/6/61/EUTRAN_arch.op.svg



What are some of those cool technologies and why do carriers want them?

Coordinated Multipoint (CoMP) advanced cell and handset cooperation allowing better use of

spectrum

Cell 1

Cell 5

Cell 4

Cell 2

Cell 7

Cell 3

Cell 6

Enhanced Inter-Cell Interference Coordination (E-ICIC) advanced cell cooperation helping prevent

interference and allowing for better use of Spectrum

Major Short Term Objective – Making better use of Spectrum


Coordinated Multi-Point and EICIC using the X2 interface

X2 interface connections are much more difficult operationallyLatency is difficult to manageLatency is not as good no matter what Latency of the first switch alone will be in the microseconds


For LTE X2 is critical and requires very low latency

Mobility Management

MobilePacket Core

X2fast

X2slow


Sync?


FDD and TDD

Most LTE is FDD today but TDD is being used more

Depending on the spectrum allocated

Timing and Synchronization Requirements

TDD FramesFDD Frames


Latency Requirements in an LTE Network

10ms Round Trip Required for user plane

Requirement for S1 Interface

X2 is 10ms, 5ms recommended

Y.1731 Used to measure this result- Used for SLA for wholesale providers

Software vs. Firmware implementations of Y.1731• Software implementations not reliable• Include latency of the software itsself




Phase and time is required in LTE-A

SyncE (frequency)

Provided by network

IEEE1588v2 PTP (phase and time)

Provided in base station

Assisted by network• By having low jitter (reduces 1588 error)

• By supplying SyncE (allows 1588 hybrid mode)

• By 1588 onpath support (T-TC and T-BC)

Poor sync results in

Less efficient radio interface

Poor performance on data traffic

Dropped calls and poor voice quality

Improved 1588v2 PTPperformance is required

Application Frequency Phase

GSM / UMTS / W-CDMA 16 ppb / 50 ppb None

UMTS / W-CDMA Femtocells n/a / 250 ppb None

CDMA2000 16 / 50 ppb ± 3 to 10 µs

TD-SCDMA 16 / 50 ppb ± 1.5 µs

LTE (FDD) 16 / 50 ppb None

LTE (TDD) 16 / 50 ppb ± 1.5 µs

LTE-A MBSFN 16 / 50 ppb ± 1.5 to 32 µs

LTE-A Hetnet Co-ordination 16 / 50 ppb ± 5 µs

LTE-A CoMP (Network MIMO) 16 / 50 ppb ± 1.5 µs to ± 500 ns


SyncE assisted 1588 PTP

SyncE in mobile backhaul network assists LTE-A bases stations to fulfill phase and time requirements

Superior network performance significantly improves phase stability with SyncE network assisting 1588v2 PTP

SyncE

Red line shows 1588 Slave clock phase error, blue shows Infinera SyncE assisted 1588 Slave clock phase error

RAASyncE

1588 PTP

SyncE assisted1588 Slave Clock

1588 SlaveClock

SyncE network between grand master and slave clock


1588 T-TC onpath support required

T-SC

Each hop contributing with traffic generating PDV in each output

GbE GbEGbE GbE GbE GbE GbE GbE GbE GbE

10G 10G 10G 10G 10G 10G 10G 10G 10G

GM

Measurement of packet delay variation (PDV) with and without T-TC:

Network with T-TC onpath support

0.2 us PDV

Slave clock (SC) keeps phase well within requirements

Network without T-TC onpath support

16 usPDV

Impossible for slave clock (SC) to keep phase accuracy


Full onpath support using 1588 Transparent Clock

Without T-TC onpath support:

Phase ~50 us

With T-TC support:

Phase ~80 ns

Reduces packet delay variation (PDV) significantly

No configuration required

Fast setup times Handles asymmetry

Advantages with Transparent Clock (T-TC)


Solve the nanosecond challenge

Solutions Tools

1 Bring a PRC clock to the cell site SyncE Hybrid mode

2 Completely remove impact of PTP packets from packet scheduling Transparent Clock

3 Onpath support using G.8271.1 Telecom Boundary Clock iSync concept

SyncE

T-BC

T-TC

T-TC

T-TCT-TC T-TC

T-TC

T-TC

IP MPLS Network

PRC / GM

HybridMode SC

T-BCT-BC


Mobile Fronthaul


Mobile Fronthaul“The connection between the

two main parts of a cellular base station; the baseband unit and radio unit.”

Mobile Backhaul“The network between

the core network and the sub networks at the edge.”

Mobile Fronthaul vs. Mobile Backhaul

Applicable to both small cells and micro cells

RRH

RRH

RRH

IP MPLSNetwork

CO

CO

CO

CO

BBU

BBU

Central Office

BBU

Mobile Fronthaul Mobile Backhaul


Why do Operators want to deploy fronthaul networks?

1. Spectrum: Move to LTE-A, take advantage of Coordinated Multi-Point and EICIC

2. Low Latency for 5G Applications

3. They are Cheaper to build

4. Operational Cost Savings


Industry challenges

OPEX (power consumption, OAM and space) represents 60% of TCO

TCO Analysis of cell site

OPEX over 7 years

CAPEX

40%TCO

60%TCO

Electricity

O&M

Site Rent

Transmission

Civil Work

Site Support

Site Acquisition & Planning

BTS

A cell site’s power consumption representsthe majority of a mobile operator’s

total power consumption

Transmission 15%

ManagementOffice, 7%

Channel6%

Cell Site 72%

Major Equipment

51%Air

Conditioners 46%

Other Support Equipment, 3%


Mobile Backhaul 2.0 and Mobile Fronthaul – details

Scalable interfaces 100M –10GE Ethernet

CE2.0 compliant Ethernet services

Multi-CoS and flexible QoS

Service OAM

Mobile Backhaul 2.0Small Cells

BBU

BBU

WiFi

Radio Access Architectures (RAA)

BBU

RRHRRH

RRH

Macro Cells

Mobile Fronthaul

Small Cells Interoperable protection schemes

Precise delivery of synchronization (frequency, phase and time-of-day)

Multi-layer management

IEEE 1588 SyncE


Mobile Fronthaul Solution

Supports challenging CPRI v6.1/OBSAI requirements

− Superior sync performance

− Ultra low latency performance

Multiple options

− Passive / Semi-passive (wavelength monitoring)

− Active

• Transparent WDM Transponder

• Transponder/Muxponder with delay compensation

• Framed WDM Muxponder

Leading low power and high density capabilities

Integrated fronthaul and backhaul in the same network optimizes fiber use

Backhaul

CO

CO

CO

CO

Central Office

Passive / Semi Passive Fronthaul

Active Fronthaul

Central Office


Unique optical capabilities – supports Centralized and Cloud-RAN networking models

Ultra low latency design and superior sync performance

Low power and high density capabilities

Integrated fronthaul and backhaul, also supporting small cells

Infinera Mobile Fronthaul - Key benefits

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