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Mobile Fronthaul – optical transport for C-RAN
architectures
Ingrid Nordmark
VP R&D Transmode
Forecasted monthly mobile data traffic
2 Restricted
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
3 Restricted
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
4
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
5
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
6
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
7
Mobile Backhaul
“The network between the core
network and the sub networks at
the edge”.
Mobile Backhaul supporting multiple Radio Accesses
8 Restricted
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
10
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
11
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
12
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
13
THANK YOU!