Wireless Ethernet Backhaul : A Carrier’s Perspective

Rajesh Yadavrajesh.yadav@verizon.comAccess Network Architecture and Design Verizon Communications

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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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*

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* Source: Heavy Reading, March 2009

Growth in High Bandwidth Base Stations

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20 fold increase in number of base stations with 24M + of backhaul capacity

Wireless Backhaul Service Requirements

MSC

TDMTDMTDMTDM

Cell Site Access Transport MSC Access

Ethernet/ C/DWDM/

??

10 x 1 GigE; 2 x 10 Gig; 5 9 s; LAG protection; dual

NNI

50 ms restoration; 5 ms OW, 1 ms FRDV

10, 150-300 Mbps; 4 9s 5; fiber

100/1000; LAG protection; dual

EVCs

ATM/FR/TDM - PW

4 QoS, p bits, Q-in-Q, shaping, L2CP blocking;

80.1ag CFM; SLA monitoring per EVC,

High burst -PIR

100-150 cell sites per

MSC

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Ethernet Backhaul Service Requirements

Cost effective scalable solution for Ethernet bandwidth up to 150-300 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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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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Present Backhaul Technologies

Leased T1 lines over copper Most prevalent for cell site backhaul today

Up to 8-10 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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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

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OTP OTPOTP

NGADM MSCAccessTransport

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

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NID

Aggregation/Core MSC

NGADM

Edge

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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Ethernet Backhaul over GPON

Shared feeder fiber and PON across

multiple cell sites and customers

Converged access for TDM

and Ethernet

Aggregated handoff at the Hub location

Bypass of IP/MPLS network depending on

traffic characteristics for more cost effective solution

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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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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Implementation of Ethernet Backhaul over GPON – cont.

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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