1. Examining the Fronthaul Network Segment on the 5G Road Why Hybrid Optical WDM Access and Wireless Technologies are required?
Philippe Chanclou, Sebastien Randazzo,
18th Annual Next Generation Optical Networking Congress
29th June – 1st July 2016
Day Three, Friday 1st July
Nice Acropolis
France

2. The Radio Access Network architecture : state of art
The current mobile architecture with distributed RAN equipment.
Backhaul
aggregation
Standard BS
Antenna
Radio unit
CPRI
Base band units
Backhaul cell site
Ethernet / Fiber
Central office
Backhaul
access

3. Optical Ethernet backhaul
The backhaul cell site is an aggregator of BBUs for data traffic based on 1Gbit/s Ethernet interface with synchronization (SyncE, IEEE 1588).
European benchmark of Ethernet leased line:
Incumbent reference Offer Ethernet leased line charges
for a local access – 5km – 24 months
source: November 2014, Wik-consult repport
Considering the market for the provision of ‘high quality’ services for business use (Mobile), this benchmark analysis describes the availability, standard prices for Ethernet leased lines supplied by former incumbent operators in the EU.
A wide variation in charges can be seen especially at speeds of 100M and above, which are typically provided via a fibre connection.

4. The Radio Access Network architecture : state of art « Cloud RAN »
The current mobile architecture with centralized RAN equipment:
Phase1 : BBU centralisation (BBU-RU link based on CPRI/OBSAI)
Phase 2 : BBU pooling
Optimal architecture for CoMP RAN features (intra and inter-cell sites).
Down sizing the form factor of equipement at the cell site
Backhaul
aggregation
Antenna
BBU
Remoted
BBU Centralised
Radio unit
Base band units
CPRI/OBSAI
over Fiber
Central office
Fronthaul
access

5. The Radio Access Network architecture : state of art « Cloud RAN »
Reach between cell sites and Central office:
For urban area (high &middle density) :
75% links have length < 4km
95% links have length < 8km
99% links have length < 20km
The existing network infrastructure is “compatible” with the fronthaul timing limitation (RTT < 150µs)
Backhaul
aggregation
Cell site to Central office reach km
Hits
Central office
Fronthaul access

6. Optical fronthaul (CPRI, OBSAI, ORI)
Passive
Active & Semi Active
Fiber-rich
network to
shared
fiber

7. Wireless fronthaul (CPRI, OBSAI, ORI)
Native wireless
with spectral efficiency
From
Small cell
or 4th sector to
Macro cell
With wireless fronthaul, turn existing macro site into local C-RAN
Easier and faster deployment, same network architecture than short reach fiber network

8. Radio evolutions from 4G Adv to 5G+
100Gbps
The ultimate 5G
25Gbps
Mm Waves
High bandwidth
Full Massive MIMO
5G+
Expected peak cell site throughput
2Gbps
700MHz (wide range of coverage)
3.5GHz with Massive MIMO
Ultra Low latency
First 5G
1Gbps
More Carrier Aggregation
256 QAM
MIMO 4*4
300Mbps
4G Adv
Time

9. The Radio Access Network architecture : the coming « 5G »
The target step of RAN architecture is the virtual RAN where a reconfigurable hardware is used. This architecture facilitates the dynamic adaptation of processing resources to the traffic request of available Radio Access Technology.
Open functional splits with L2 or L1interfaces
BBU & RRH partitioning
BBU L3 & L2…
…L2 & L1 RRH
CPU & real time constants
vBBU L3 L2 L1 RF
CPRI
OBSAI
PDCP
RLC
MAC
FEC
QAM
FFT
ressource
mapping
OAM X2 S1
RRC
Service
PDCP
RLC
RLC
MAC
MAC
MAC
PHY
Split
PHY
CPRI
OBSAI
Fronthaul bandwidth
Low
High
CoMP capability
DPS, CS, CB, …
… JT/JR
CoMP: Coordinated Multi-Point
DPS: Dynamic Point Selection
CS: Coordinated Scheduling
CB: Coordinated Beamforming
JT: Joint Transmission
JR: Joint Reception

10. The Radio Access Network architecture : the coming « 5G »
The low part of the BBU (L1 and potentially a part of L2) cannot be virtualized due to CPU and real time constraints
The high part can be virtualized (L3 and a part of L2)
The virtualization is explicitly assumed to be part of the 5G architecture and design principles
vRAN is a prerequisite of the network slicing
vBBU L3&L2
Antenna
Load balancer
& switch
Radio unit
Cell site
aggregator
L1&L2
Ring
Aggregation
Network
Master
central
office
(Data center)
Ethernet / Fiber
Access
Network

11. The Radio Access Network architecture : the coming « 5G »
L2 & L3 virtualisation
The optimal architecture for CoMP inter cell sites should request:
L1 & L2 Centralisation
Pool of cell site aggregators : still CPRI/OBSAI network segments
vBBU L3&L2
Antenna
Ethernet / Fiber
Pool of cell
site aggregators
L1&L2
Radio unit
Ring
Aggregation
Network
Master
central
office
(Data center)
CPRIs over Fiber
Access
Network

12. The Radio Access Network architecture : the coming « 5G »
Backhaul & Fronthaul architecture evolution:
Aggregation Network
Access Network
Cell site
3 sectors
20 MHz – MIMO4x4
BBU
Ethernet Backhaul
300 Mbit/s (1GEth)
Additional data rate vs.
backhaul dimensioning:
minimum +20%
maximum x3
BBU pool
CPRI : 3 x 5Gbit/s (3 )
≈ 100µs / 20 km
vBBU
Ethernet New Functional Split
360 Mbit/s < ? < 900 Mbit/s
Cell site
gateway
≈ 2ms / 400 km

13. Mobile Backhaul and Fronthaul line rate
CPRI/OBSAI rate per RRH
Eth. cell site gateway
(new functional split)
Gbit/s
Compressed CPRI rate per RRH
100 25
Eth. Backhaul
per BBU pool 10
Transmission line rate 5 2 1
Eth. Backhaul per cell site
0.1 2G
Radio Access Technologies 3G
4G to 4G++
5G to G+

14. Mobile backhaul and fronthaul optical technologies for last miles
Aggregation Network
Access Network
(last mile network segment)
Cell site
BBU
BBU pool
vBBU
Cell site
gateway

15. Mobile backhaul and fronthaul optical technologies for last miles
Aggregation Network
Access Network
(last mile network segment)
Cell site
Ethernet backhaul
PtP switch (1G10G 40G 100G)
PtP router
G/XGS-PON (synergy with FTTH roll out)
BBU
Switch
FTTH ONT
BBU pool
vBBU
Cell site
gateway

16. Mobile backhaul and fronthaul optical technologies for last miles
Aggregation Network
Access Network
(last mile network segment)
Cell site
BBU
BBU pool
CPRI/OBSAI/ORI fronthaul
Transceivers
Mux/DeMUX 
WDM technology : CWDM, DWDM, PtP WDM
Potential synergy with FTTH roll out
(supernumenary fiber, sharing infrastructure with wavelength overlay)
vBBU
Cell site
gateway

17. Mobile backhaul and fronthaul optical technologies for last miles
Aggregation Network
Access Network
(last mile network segment)
Cell site
BBU
BBU pool
Transceivers
New backhaul
for new functional split
vBBU
PtP router (1G40G 100G)
XGS-PON, NG-PON2 TWDM or PtP WDM
(synergy with FTTH roll out)
Switch
FTTH ONT
Cell site
gateway

18. Optical access trends for Mobile application
Last-mile mobile backhaul context-synthesis:
Mobile backhaul is done by DSL or fiber PtP with Switch/Router.
Fiber will the enabler medium of backhauling
Mobile backhaul is already supported by G-PON (with synchronisation feature)
Tomorrow, more antenna sites & more data rate (5G) require:
synergy with FTTx roll out
new PON generation : XGS-PON, NG-PON2 (TWDM & WDM-PON)
FTTH context-synthesis:
What G-PON offers in term of bit rate, is enough for the backhaul 2G/3G/4G.
XGS-PON will be soon available to support 5G
WDM in access is in progress by NG-PON2 to support PtP WDM or TWDM (100G)
Data rate capacity of FTTx - PON system
(Down-/Up-stream)
Timeline
2006
2,5/1,25 Gbit/s
XGS-PON
XG-PON 1
G-PON
10/2,5 Gbit/s
10/10 Gbit/s
the potential
25G-PON
25/10 Gbit/s
25/25 Gbit/s
40/10 Gbit/s
80/80 Gbit/s
TWDM-PON
&
PtP WDM PON
grey optics
WDM optics
ITU-T G.984
ITU-T G.987
ITU-T G.9807
ITU-T G.989
2018 – 2020 ?
100G-PON
100 Gbit/s
presentation title 18

19. Optical access trends for Mobile application
presentation title 19

20. 1 2 3 4 4 keys points Conclusion
CPRI fronthaul experimentations in France in opportunist mode
Fibber has the preferred medium of “X”-hauling 3 4
New functional split based
on Ethernet is coming
for 5G
Heterogeneous last-mile:
-PtP Ethernet (switch/router),
-PON for FTTx synergy,
-WDM for efficient sharing
presentation title

21. Thank You. Acknowledgment: