pon architecture for wireless backhaul
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PON Architecture for Wireless Backhaul. Paul Wilford. October 28, 2009. 1. The mobile backhaul problem. The mobile backhaul problem. Current Wireless Carrier Environment Increased bandwidth demands Due to more advanced users and handsets Mobile broadband (killer app) - PowerPoint PPT PresentationTRANSCRIPT
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PON Architecture for Wireless Backhaul
October 28, 2009
Paul Wilford
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The mobile backhaul problem 1
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The mobile backhaul problem
Current Wireless Carrier Environment
Increased bandwidth demands
Due to more advanced users and handsets
Mobile broadband (killer app)
TDM Backhaul is not efficient for packet data
Doesn’t fit well in traditional T1 Architecture
Current Wireless Carrier Environment
Increased bandwidth demands
Due to more advanced users and handsets
Mobile broadband (killer app)
TDM Backhaul is not efficient for packet data
Doesn’t fit well in traditional T1 Architecture
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The mobile backhaul problem
Data is becoming the primary use of the network Data is becoming the primary use of the network
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2005-2010 2010-20202000-2005
ARPUARPU
TrafficTraffic
The mobile backhaul problem
New mobile data services require exponentially increasing bandwidth but generate less revenue per bit transported than voice services. 100 Kb/s for GSM GPRS (downlink)
≥100 Mb/s for LTE (downlink)
This will break the traditional voice-optimized TDM Mobile Backhaul (MBH) network
Legacy leased line capex and opex scale linearly with bandwidth
New mobile data services require exponentially increasing bandwidth but generate less revenue per bit transported than voice services. 100 Kb/s for GSM GPRS (downlink)
≥100 Mb/s for LTE (downlink)
This will break the traditional voice-optimized TDM Mobile Backhaul (MBH) network
Legacy leased line capex and opex scale linearly with bandwidth
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Landscape of today 2
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Landscape of today
3G1XHRPD
IP Channel BTS
Voice Channels
DoRNC
PDSN/HSGW
GSMUMTS
IP Channel
BaseStation
NodeB
Voice Channels
Separate Core Networks for different
Radio Access Networks
•SGSN – Serving GPRS Support Node
•GGSN – Gateway GPRS Support Node
•PDSN – Packet Data Support Node
•HSGW – HRPD Serving Gateway
•RNC – Radio Network Controller
•DoRNC – Data Optimized RNC
•BSC – Base Station Controller
•MSC – Mobile Switching Center
•HRPD – High Rate Packet Data (1xEV-DO)
BTS
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Landscape of today
Examples of customer deployments – Customer ‘X’
Customer ‘X’ primarily uses ATM for backhaul. The overall strategy is to seek higher-capacity, lower-cost solutions as the more data-centric technologies such as HSDPA drive capacity requirements.
The target state architecture is one that is flexible and can scale as capacity demand increases. Some solutions being considered include fiber to the cell site and bonded copper.
Customer ‘X’ has a combination of GSM/UMTS networks and will need to integrate backhaul for all networks as it migrates from GSM to UMTS to LTE.
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Landscape of today
Examples of customer deployments – Customer ‘Y’
Customer ‘Y’s backhaul strategy consists of delivering Ethernet over the existing copper infrastructure with a migration to fiber-based Ethernet backhaul services.
Customer ‘Y’ plans to leverage its Fiber to the Premise (FTTP) network with pseudowire to provide backhaul services.
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Landscape of Tomorrow 3
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Landscape of tomorrow – Evolution to a common core
GSMUMTS
IP Channel
BaseStation
NodeB
Voice Channels
3G1XHRPD
IP Channel BTS
Voice Channels
DoRNC
HSGW
MME PCRF
SGW
PDN GW
LTE
RNC
GSM and CDMA voice and data networks converge into an IP-based evolved packet core (EPC)
For LTE, IP data from the eNodeB connects directly to the EPC
BTS
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Landscape of tomorrow - 4G/LTE Mission
High Peak Data Rates
100 Mbps DL (20 MHz, 2x2 MIMO)50 Mbps UL (20 MHz, 1x2)
High Peak Data Rates100 Mbps DL (20 MHz, 2x2 MIMO)
50 Mbps UL (20 MHz, 1x2)
Improved SpectrumEfficiency
3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in UL
1 bps/Hz broadcast
Improved SpectrumEfficiency
3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in UL
1 bps/Hz broadcast
Improved CellEdge Rates
3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in ULFull Broadband Coverage
Improved CellEdge Rates
3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in ULFull Broadband Coverage
Packet Domain OnlySimplified Network
Architecture
Packet Domain OnlySimplified Network
Architecture
Scalable Bandwidth1.4, 3, 5,
10, 15, 20 MHz
Scalable Bandwidth1.4, 3, 5,
10, 15, 20 MHz
Network Co-existenceUMTS, GSM, HRPD, CDMANetwork Co-existenceUMTS, GSM, HRPD, CDMA
Low Latency< 5ms User Plane (UE to RAN edge)
< 100ms camped to active< 50ms dormant to active
Low Latency< 5ms User Plane (UE to RAN edge)
< 100ms camped to active< 50ms dormant to active
*Assumes 2x2 for DL in LTE, but 1x2
for HSPA Rel’ 6
Radio Access Network
Core Network
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Landscape of tomorrow – Technology Innovation
With increased spectral efficiency, reduced latency and increased bandwidth, LTE enables innovations to improve performance at the handset.
An example of this is CoMP.
With increased spectral efficiency, reduced latency and increased bandwidth, LTE enables innovations to improve performance at the handset.
An example of this is CoMP.
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What is CoMP?4
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What is CoMP? – Cooperative Multi-Point
Controller
High-speed backhaul
All signals are potentially useful – no interference!
Overcome inter-cell interference by coordinating Tx/Rx at several base stations, thereby greatly increasing user rates and system capacity.
Each user is connected to several bases
Desired signal
Desired signal
Interference
Data rates limited by interference
Each user is connected to a single base
Today’s network
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What is CoMP? - System Outline
Base Station
Base Station
Base Station
Base Station
CoMP Processor
Backhaul that conveys both uplink and downlink baseband
signal.
Performs downlink and uplink CoMP beamforming.
Base stations communicate with a centralized CoMP processor. The backhaul network conveys both uplink and downlink signals.Base stations communicate with a centralized CoMP processor. The backhaul network conveys both uplink and downlink signals.
Handset
Handset
Handset
Handset
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What is CoMP? – Coherent vs. Non-Coherent
Coherent
Uses I/Q samples for CoMP processing in time or frequency domain
Requires the highest bandwidth from the backhaul network
Potential for greatest gain at the handset
Non-coherent
Uses soft bits for CoMP processing
Requires less backhaul bandwidth than coherent scheme
Coherent
Uses I/Q samples for CoMP processing in time or frequency domain
Requires the highest bandwidth from the backhaul network
Potential for greatest gain at the handset
Non-coherent
Uses soft bits for CoMP processing
Requires less backhaul bandwidth than coherent scheme
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What is CoMP? – Uplink and Downlink
Uplink
To perform uplink CoMP, I/Q samples or soft bits must be transmitted to the CoMP processor
Downlink
To perform downlink CoMP there are two options:
Data and beam forming coefficients sent to each base station
I/Q samples or soft bits sent to each base station
After CoMP processing performed at CoMP processor
The backhaul network must support the required data distribution to all nodes
Channel State Information is required for beam forming
Different base stations adjust the amplitude and phase of the transmission of the signals to the handsets to achieve improved handset performance
Uplink
To perform uplink CoMP, I/Q samples or soft bits must be transmitted to the CoMP processor
Downlink
To perform downlink CoMP there are two options:
Data and beam forming coefficients sent to each base station
I/Q samples or soft bits sent to each base station
After CoMP processing performed at CoMP processor
The backhaul network must support the required data distribution to all nodes
Channel State Information is required for beam forming
Different base stations adjust the amplitude and phase of the transmission of the signals to the handsets to achieve improved handset performance
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What is CoMP? - Requirements
CoMP schemes demand for
High bandwidth
multiple Gbit/s (DL &UL coherent, time domain)
<1 Gbit/s (DL & UL coherent, frequency domain)
about 100 Mbit/s (non-coherent)
Low latency
about 1 ms (all schemes, optimal case)
high backhaul latency may become a show stopper for CoMP– Need for a backhaul solution that is low latency
The Technical challenge is to meet the latency requirement under fully loaded conditions. This requires sophisticated scheduling and MAC Layer processing.
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Different PON technologies5
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Different PON technologies
PON technologies:
APON – ATM PON
First PON standard – used primarily for business applications
622 Mbps/155 Mbps
BPON – Broadband PON
Extension of APON – added OMCI (OAM Management Control Interface) and WDM capability
622 Mbps/155 Mbps
GEPON/EPON – Ethernet PON
IEEE 802.3ah Standard
1Gbps/1Gbps
GPON – Gigabit PON
ITU-T G.984 Standard
Evolution of BPON
2.5Gbps/1.25Gbps
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Different PON technologies
PON technologies:
10G EPON – 10G Ethernet PON
Extension of GE/EPON
10 Gbps/1 Gbps
XGPON – 10G GPON
Extension of GPON
XGPON1 – 10 Gbps/2.5 Gbps
XGPON2 – 10 Gbps/10 Gbps
GPON is a suitable backhaul technology for packet-based services
For increased capacity and to support applications like CoMP, XGPON2 is the
best backhaul solution
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Synchronization6
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Synchronization: Problems with synchronization
Base station radio interface typically requires some level of synchronization
Frequency accuracy
Time/phase accuracy
Base station backhaul interface (typically legacy base stations) may be synchronous (T1/E1)
Synchronization considerations
Relative phase stability
Mobile hand-off between base stations
Coherent CoMP
Core network may or may not be synchronous
(Traditional) Ethernet, Synchronous Ethernet, SONET, etc.
Separate timing distribution network may or may not exist
GPS, NTR, etc.
Base station radio interface typically requires some level of synchronization
Frequency accuracy
Time/phase accuracy
Base station backhaul interface (typically legacy base stations) may be synchronous (T1/E1)
Synchronization considerations
Relative phase stability
Mobile hand-off between base stations
Coherent CoMP
Core network may or may not be synchronous
(Traditional) Ethernet, Synchronous Ethernet, SONET, etc.
Separate timing distribution network may or may not exist
GPS, NTR, etc.
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Synchronization: GPON Mobile Backhaul End-to-End Synchronization
OLTOLT
GPON
RNCBSC
RNC/BSCGateway
IP/ Ethernet Network
GPON-fed cell site gateway (ONU)
Cell site
E1, Eth
GPON PHY 8 kHz clockE1/Sync E
PRC PRC
IEEE 1588v2 (when PRC not avail. at OLT)
E1, Eth
The GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 microsecond framing
Therefore GPON provides deterministic synchronization like TDM
However, CoMP requires something better
To achieve more precise timing synchronization, provisions must be made to compensate for the OLT-ONU delay variations
The GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 microsecond framing
Therefore GPON provides deterministic synchronization like TDM
However, CoMP requires something better
To achieve more precise timing synchronization, provisions must be made to compensate for the OLT-ONU delay variations
OLT
ONU
ONU
ONUGPON frame t
t
t
t
GPON frame
GPON frame
GPON frame
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The MAC Layer7
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The MAC Layer: GPON
GPON QoS is maintained through transmission containers (T-CONTs)
T-CONT classes
Type 1 – fixed bandwidth
Type 2 – assured bandwidth
Type 3 – allocated bandwidth + non-assured bandwidth
Type 4 – best effort
Type 5 – superset of all of the above
Scheduling algorithm at the GEM Layer guarantees that transmission container bandwidth and latency guarantees are satisfied under fully loaded conditions
Dynamic Bandwidth Allocation
Maximum fiber bandwidth utilization
Based on queue status from ONUs
Security (via AES)
FEC
GPON QoS is maintained through transmission containers (T-CONTs)
T-CONT classes
Type 1 – fixed bandwidth
Type 2 – assured bandwidth
Type 3 – allocated bandwidth + non-assured bandwidth
Type 4 – best effort
Type 5 – superset of all of the above
Scheduling algorithm at the GEM Layer guarantees that transmission container bandwidth and latency guarantees are satisfied under fully loaded conditions
Dynamic Bandwidth Allocation
Maximum fiber bandwidth utilization
Based on queue status from ONUs
Security (via AES)
FEC
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The MAC Layer: Backhaul challenges
CoMP data processed and sent to downstream path for scheduling/reflection to ONUs
Very low latency requirement of 1 ms
Handoff between eNodeBs requires tighter synchronization at base stations
OLT must send additional information to ONUs so they know neighboring ONU timing for handoffs
FEC at 10 Gbps
Completing R-S computations for 10 Gbps within 125 us is challenging
CoMP data processed and sent to downstream path for scheduling/reflection to ONUs
Very low latency requirement of 1 ms
Handoff between eNodeBs requires tighter synchronization at base stations
OLT must send additional information to ONUs so they know neighboring ONU timing for handoffs
FEC at 10 Gbps
Completing R-S computations for 10 Gbps within 125 us is challenging
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The MAC Layer:
BWMap(Dual Port)
MAC CORE
Processor I/F
GEM LayerDownstream
(encapsulation)
TC LayerDownstream
AESEncryption
FECEncode
PHY Layer Downstream
GEM LayerUpstream
TC LayerUpstream
FECDecode
PHY LayerUpstream
PLOAMDownstream
PLOAMUpstream
Regs
I/O Macro
I/O Macro
I/O Macro
I/O Macro
I/O I/O
I/O Macro
PLSUpstream
DBRUpstream
North Bound
I/F
South Bound
I/F
Scheduling for QoS and CoMP reflection
CoMP processing. Data fed to downstream GEM Layer
for reflection to ONUs
S1/X2 translation
S1/X2 translation 10G FEC decode
10G FEC encodeCoMP timing messages
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Conclusions8
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Conclusions
XGPON2:
Is a backhaul solution that can accommodate growth in bandwidth demand
Is a backhaul solution that connects to the simplified network architecture
Is a backhaul solution that can integrate data from 2G,3G and LTE networks
Is a backhaul solution that can handle the uplink and downlink data
distribution requirements for applications like CoMP
Is a backhaul solution that is synchronous and is compatible with IEEE
1588v2 synchronization through packet networks
Is a backhaul solution that contains efficient scheduling in the MAC layer for
maintaining QoS under fully loaded conditions
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Thank You!
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Backup Slides
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The MAC Layer: ONU block diagram
BWMap(Dual Port)
Processor I/F
PHY LayerDownstream
TC LayerDownstream
AES Decryption
FECDecode
PHY LayerUpstream
TC LayerUpstream
FECEncode
GEM LayerUpstream
PLOAMFIFODS
Regs
I/O Macro10G
I/O Macro
MAC CORE
GEM LayerDownstream
PLOAMFIFOUS
I/OMacro(s)
I/O Macro
I/O Macro
USER I/FTranslation
USER I/FTranslation
I/O I/O
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SHDSL.bisSHDSL.bis
GPONGPON
0,512
4
8
10
24
100
> 1000
500
1
DL
Sp
eed
[M
bp
s]
2000
2002
2004
2006
2008
2010
2012
GPRS
UMTSWireless
10G PON10G PON
ADSL
ADSL
ADSL2ADSL2
Wireline
HSPAHSPA
Conclusions: Broadband Access Networks can support 3G/LTE Bandwidth Requirements
LTELTE
ADSL2+ADSL2+
VDSL2VDSL2
HSPA+HSPA+
GPON satisfies LTE bandwidth needs
• 2.5G DS/1.25G US shared
• Optical split adjusted as required.
• Future evolution to 10G PON (λ overlay on same PON)
Bonded VDSL2 supports HSPA+ and early LTE
ADSL2+ and SHDSL.bis are tactical solutions for 2G 3G
XGPON2 satisfies LTE bandwidth needs
• 10G DS/10G US shared