1. Wireless Ethernet Backhaul : A Carrier’s Perspective
Rajesh Yadav
Access Network Architecture and Design
Verizon Communications

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Presentation Outline
Trends in Wireless Backhaul Bandwidth
Ethernet Backhaul Service Requirements
Present Wireless Backhaul Technologies
Drivers for Ethernet Backhaul over PON
Implementation of Ethernet Backhaul over GPON
Concluding Remarks
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3. Wireless Backhaul Bandwidth Demand
Significant increase in broadband mobile users
Data and multimedia mobile applications driving bandwidth utilization exponentially
Higher growth possible with faster adoption of LTE technology
150+ Mbps bandwidth requirements per cell site shared by up to 3 operators
Number of 3G/4G cell site expected to grow from 72,000 to 225,000 by 2012*
* Source: Heavy Reading, March 2009
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4. Growth in High Bandwidth Base Stations
20 fold increase in number of base stations with 24M + of backhaul capacity
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5. Wireless Backhaul Service Requirements
50 ms restoration; ms OW, 1 ms FRDV
10 x 1 GigE; 2 x 10 Gig; 5 9 s; LAG protection; dual NNI
10, Mbps; 4 9s 5; fiber 100/1000; LAG protection; dual EVCs
Ethernet/ C/DWDM/ ??
MSC
4 QoS, p bits, Q-in-Q, shaping, L2CP blocking; 80.1ag CFM; SLA monitoring per EVC, High burst -PIR
cell sites per MSC
ATM/FR/TDM - PW
Transport
MSC Access
Cell Site Access
Source: VzW
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6. Ethernet Backhaul Service Requirements
Cost effective scalable solution for Ethernet bandwidth up to Mbps per cell site
Initial requirements from carriers is for guaranteed bandwidth between cell site and MSC location
Maintains the current model of using TDM based transport “pipes”
Expected evolution to multiple classes of service to better match traffic characteristics to the transport need
Circuit emulation support for TDM/ATM/FR
Migration of cell sites with existing TDM/ATM/FR interfaces on a common Ethernet backhaul network
Coexistence of TDM and Ethernet backhaul expected for sometime
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7. Ethernet Backhaul Service Requirements – cont.
Low latency, jitter and packet loss transport
Multiple classes of service
Transport network reliability 5 9’s
50 ms restoration desired
Timing and frequency synchronization
Performance monitoring and Real time SLAs
Comprehensive Network management and OAM capability
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8. Present Backhaul Technologies
Leased T1 lines over copper
Most prevalent for cell site backhaul today
Up to T1s used per cell site
Widely available
High cost
Not scalable to meet projected high bandwidth demands
Optimized for voice traffic with dedicated bandwidth with little flexibility for bursty traffic
High capacity Microwave Ethernet backhaul
Better bandwidth scalability compared to leased T1 lines
Use of licensed spectrum
Somewhat limited reach and line of sight requirements
Susceptible to interferences
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9. Present Backhaul Technologies
Ethernet over SONET (Ethernet Private Line)
Point-to-Point Ethernet transport
Can scale to very high bandwidth to meet the current and projected bandwidth demand
Network bandwidth can be increased at STS1 granularity
50 ms restoration capability in the access and transport network
Significant upfront cost for dedicated fiber facilities and optical equipment
Transport
NGADM
Access
MSC
OTP
OTP
OTP
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10. Present Backhaul Technologies
Switched Ethernet Network
Provide flexible bandwidth options with multiple class of services to support voice, video and data traffic
Point to point Ethernet virtual connection (EVC)
Use of Dedicated dark fiber pair or CWDM
Limited availability in cell site locations
Providing redundancy in the access can be expensive
Dedicated pair of fiber required for every cell site
Could also use access CWDM infrastructure
Desire for dedicated bandwidth from wireless carrier reduces the attractiveness of cost effective shared backbone network
Edge
NID
Aggregation/Core
MSC
NGADM
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Why GPON?
GPON (Gigabit Passive Optical Network) provides high bandwidth capacity which can be used in effective “pay as you grow” model
2.4 Gbps in downstream and 1.2 Gbps in upstream generally shared across 32 customers
 Cost efficient point–to–multipoint utilization of fiber without need for dedicated fiber infrastructure
Only ~25% cell site are currently passed with fiber
NG PON will be able to support up to 10 Gbps
Growing availability of GPON deployment in cell site locations
Highly reliable with no active components in outside plant
Ability to provide smooth migration from current TDM based backhaul to scalable Ethernet backhaul using hybrid TDM and Ethernet backhaul model
Convergence of residential and business services over common infrastructure
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12. Ethernet Backhaul over GPON
Aggregated handoff at the Hub location
Converged access for TDM and Ethernet
Shared feeder fiber and PON across multiple cell sites and customers
Bypass of IP/MPLS network depending on traffic characteristics for more cost effective solution
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13. Implementation of Ethernet Backhaul over GPON
GPON ONT can cost effectively support from 10Mbps to potentially 100s of Mbps to a cell site
Bandwidth can be added on as needed basis
Support for guaranteed bandwidth to emulate current guaranteed “pipe” model with TDM based backhaul
Evolution to model with multiple classes of services to optimize bandwidth need to the traffic characteristics for more cost efficient backhaul
Class of service differentiation based on 802.1p (p-bits) in VLAN header or DSCP in IP header
GPON provides support for carrying both Ethernet and TDM traffic
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Implementation of Ethernet Backhaul over GPON – cont.
Synchronization options with Ethernet backhaul over GPON
Outside of the Ethernet transport network
Via GPS at base station
Retention of a T1 circuit for synchronization
Packet Based synchronization using dedicated packet flow
IEEE 1588 v2
Clock carried by circuit emulated data (e.g. T1) over Ethernet Transport
Synchronous Ethernet
GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 ms framing
Transfer of synchronization over Ethernet interface on ONT
Redundancy can be supported at the cell site by providing dual connections from diverse PONs
Encryption of traffic with in GPON for additional layer of security
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Concluding Remarks
Increase in bandwidth demand for mobile backhaul with new data and multimedia mobile applications and evolution to 4G technologies is creating significant opportunity for Ethernet backhaul
Wireless carriers are looking for cost effective, scalable and flexible solution to meet expected bandwidth demand
TDM and Ethernet will coexist for some time and backhaul solution should provide converged access to support this hybrid model with easy migration to Ethernet backhaul
GPON can provide scalable and cost effective “pay as grow” solution for Ethernet backhaul as the bandwidth demand for wireless backhaul grows overtime with evolution of wireless networks towards 4G technologies
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