1

NG PON and 5G

Ed Harstead, Bill Powell – NokiaEd Walter – AT&T

22

The road to PON success: leveraging technologies matured in other domains

50 Gb/s

B/E/GPON 10G PON

2000s 2010s

622 Mb/s, 2.5 Gb/s 10 Gb/s

2015 2020 2025

25G PON

25 Gb/s

Metro

Long haulData center

The old paradigm The new paradigm

First mass deployments:

40 Gb/s Per channel:

50G PON

33

The 25G PON ecosystem: closer look

Q: What do we get from the 25G/100G Ethernet ecosystem?

A:

• 25G O-band DML

• 25G O-band EML

• 25G APD

• 25G TIA

• 25G SERDES

25G ecosystem

Source: LightCounting, “High-speed Ethernet Optics, 9th Edition”, March 2019.

44

The PON “lag”: Each time, 3 technical challenges to overcome

TRx TRx

Point-to-point link

PON: point-to-multipoint link

OLT

ONU 1

ONU Npower splitter

Lower cost target

Larger power budget

Burst mode

1:N

55

IEEE

• IEEE has standardized 25G EPON in P802.3ca

• Stable draft D3.1

• Standard to be published later this year.

ITU-T

• ITU-T SG15/Q2 started a project for >10G PON: G.hsp.

• G.hsp includes 50G PON, but overlooks 25G PON: a mistake.

• A critical mass of ITU-T operators and vendors are proposing a new project to support 25G PON.

• Like with XGS-PON, it is desirable to have common 25G PON PMD requirements for IEEE and ITU-T PONs

25G PON: standardization status

Operators1. AT&T

2. KT

3. SKT

4. TI

5. Telus

6. BT

7. NBN

Government research organizations

1. ETRI

Vendors1. Nokia Corp2. Nokia USA3. Broadcom4. Intel5. Tibit6. Oki7. Corning 8. Sumitomo

9. Mitsubishi10. Ericsson

18 co-signers for 25G PON, ITU-T plenary, 5 February 2020

6

25G PON For Business

OR

• IEEE P802.3ca allows for Co-Existence of GPON with 25G PON or XGS with 25G PON. The figure above illustrates the latter.

• Co-Existence is not a prerequisite for 25G PON but would allow for reuse of fiber plant (and splitters).

• The separation of Consumer to XGS and Business to 25G PON allows for a cost-effective, higher end service development for Business without impacting the Consumer customer.

Fiber Cross ConnectFiber Serving Terminal

Distribution

Fiber (F2)

BusinessConsumer

25G PONXGS PONXGS PON XGS PON

Mixed Use

(Business/Consumer)

XGS PON for Consumer

25G PON for Business

OLT

OLT

25G PON

XGS PON

Fiber Frame

Feeder Fiber (F1)

1

n

Split

ter

1

n

Split

ter

Co-Existence

77

5G transport over PON: value proposition

Transport

dominates

small cell

capex

• PON transport has been technically feasible for LTE

macrocells. But few PONs were deployed.

• But transport costs need to be solved for the dense 5G business case.

Source: Mobile Experts, “5G Millimeter Wave 2019: Radio Architecture and Outlook”, March 2019.

• PON transport will make sense for 5G when operators evolve to 5G densification.

• In particular, when leveraging an FTTH network for 5G, PON can

- speed time-to-market,

- save capex and facilitate the dense 5G business case.

WDM,

PTP fiberPON

Low density High density

FTTHLTE macrocells 5G small cells?

Currency units Removed due to IEEE rules

RelatitiveCost1.4

1.2

1.0

0.80

0.60

0.40

0.20

0.00

8

5G transport requirements CU : Central Unit (may be virtualized)DU : Distributed UnitRU : Radio Unit

5G New Core Antenna

Fx/eCPRI

C-RAN

Fronthaul

S1

D-RAN

Backhaul

F1

Cloud-RAN

(vRAN)

“Midhaul”

1x 5x

<0.250ms<8ms>20 ms

Data rate

Latency

Symmetry

1x

CU DU RU

9

Outside of China, midhaul is forecasted to be required for >50% of all radio sites.

Midhaul segment of the 5G market

“DU with RU” = midhaul transport

Source: Ovum, “Mobile operators can move beyond dark-fiber 5G transport”, July 2019.

10

Cloud-RAN (vRAN) architectures: midhaul F1 transport over 25G PON

vCU servers

ABIL DU

DU+RUs

OLT

ONU

RUsF1 over 25G PON

ONU

#RUs/ONU, small cell examples1: building façade2: lamp post in middle of street3: traditional area coverage (macro)4: at street intersection; rooftop

÷ =25G PON minimum support: 8-44 ONUs

Typ. configurations 25G PON capacity

Sub-6 GHz, 100MHz, 8 layer MIMO

≥33 RUs per PON

mmWave, 400MHz, 2 layer MIMO

≥44 RUs per PON

D071, Q2, Dusseldorf, Oct/19 - Transport dimensioning for the F1 interface (aka midhaul), T. Pheiffer

11

Alternative: WDM PON redux

• Low latency

• Optimized for non-stat-muxable traffic

• Requires relatively exotic and expensive optics

Fronthaul transport challenges

TDM PON:

• Stat muxing of eCPRI traffic: doable in principle, not yetquantifiable.

• How to support stat muxing and low latency simultaneously?

Solution: - Cooperative DBA: being standardized in ORAN and ITU-T as “CTI”.- CTI addresses the stat muxing challenge as well as the PON

ranging window

OLTDUCU

RUs

Fx eCPRI over PON

ONU

12

TDM and WDM PON architectures primer: WDM PON is strictly a fronthaul play

Attribute TDM PON WDM PON

Architecture

Physical architecture point-to-multipoint point-to-multipoint

Logical architecture point-to-multipoint point-to-point

Branching elements one power splitter two DWDM muxes

OLT ports per ODN one one for each ONU

Transmitter wavelength fixed OLT: fixed, ONU: tunable

Wavelength tolerances relaxed DWDM

ONU

OLT ONU

ONUOLT

OLTONU

ONU

ONUOLT

These will have a significant impact on cost

Can co-exist with legacy PONs over existing ODNs

Will not co-exist with legacy PONs, will require new ODNs

13

• 25G PON can leverage the data center ecosystem for mature low-cost optics and electronics.

• 25G PON is an ideal solution for 5G midhaul/backhaul especially in an FTTH footprint

• 5G fronthaul poses a larger challenge for TDM PONs. WDM PON is an interesting alternative but not without its own challenges.

Conclusions

14