Design - Webinar Part 2

Passive Optical Network Design- Design and Cost Considerations

Patricia AlsinaJanuary 29, 2014

Telecom Commercial Operations © 2013 Corning Incorporated 2

Agenda

• PON Design Objectives

• Review of Architectures

• Design and Cost Considerations


PON Design Objectives

• A future-proofed OSP network– Easily configure subscriber driven changes– Ability to adjust split ratios or offer dedicated fibers– Scale network to take rates

• Minimize initial capital investment– Understand the cost components of the system for both CAPEX and

OPEX– Ability to defer costs until revenue is generated– Will “cookie cutter” design approach work

• Minimize installation cost and complexity– Understand installation cost drivers

• available labor, skill levels, equipment– Understand deployment speed requirements


Central Switch Homerun (CSH)

1x32 splitter


Local Convergence (LC)

1x32 splitter


Distributed Splitting (DS)

1x4 splitter

1x4 splitter

1x4 splitter

1x8 splitter


Cost Components to Consider

• Product costs

• Cable install methods– Aerial, buried, duct– Lash, self-support, trench, plow, bore, pull– Existing duct or new

• Splicing– Set-up charges– Per splice charges

• Product placements– On pad, pole, strand, vault, pedestal


Additional Cost Components

• Time to install / deploy• Product deferment• Labor skill levels and availability• Labor charge structures ($ per foot vs. $ per job)• Product purchasing and inventory

– Physical storage space– Part number management

• Development of design • Development and documentation of splice plans• Testing requirements• Specialized equipment requirements

– Splicing, testing


Typical FTTH Network

CSC LCP

NAP

ONT - NID

(LC)(CSH)


Overview of Design Process Steps

“Work from homes to CSC”

1. Determine NAP groupings2. Bring NAPs together by determining splice points3. Decide on optimum cable paths to link splice points4. Bring cables to convergence point(s)5. Select convergence products(s)6. Determine feeder cable size and path7. Provide hardware for CSC


Design Considerations – NAP Placement

• Product selection will drive ability to defer drops – Drops spliced at NAP

• Splice in 100% and store• Splice in as needed

– Drop connectorized at NAP• Easier to defer product until service request

• Drops placement decisions will drive NAP placement decisions– Crossing street vs. same side of street– Lot front distances– Street front vs. backlot


Drop Length Impact (crossing vs. same side of street)

300-ft of drop cable

Length difference = 50-ft



1800-ft of drop cable Length difference = 1050-ft


Lot Front Distances

• Larger lot fronts require longer drops• Cost of longer drops and to install drops might outweigh savings

gained from larger NAP size


Street front vs. back lot

Street front

Back lot

Aerial

More prevalent in Greenfield

Easy to defer drops


Sample Design – NAP Placement


Cable Access Points – One Side of Street

4 splices 4 splices 4 splices

12 splices

• Considerations:– Balance installation cost and time required to install three splice points

versus additional cost to install multiport tails– More splice points may become advantageous as length of multiport tail

increases


Pre-terminated Cable

• Replaces splice points with factory installed tap• Allows deferment of multiport

4-F tap 4-F tap 4-F tap

12-F tap


Cable Access Points – Both Sides of Street

• Three Scenarios– Access cable at each NAP

• Cable on both sides of street• Multiple splice points• One street crossing

– Access cable and cross street• Cable on single side of street• Reduced splice points• More street crossings

– Access cable at one point• Cable on single side of street• Minimum splice points• One street crossing


Cable Access Points - Side Streets

• Place access point at existing NAP• Multiple options for serving side streets


Side Street – NAP Options

Cable - Multiple Splice Points Cable – Single Splice Point

24

6

6

6

6

24

24


Side Street – NAP Options

Standard Multiports

24

Multiports in Series

24


Side Street – Pre-Terminated Cable NAP Options

Multiports in Series

Two 12-F taps


Sample Design – Multiport Tails and Splice Points


Cable Placement

• “Connect the dots” – cable access points• When possible, identify accessible ducts or strand prior to design• Identify main cable paths and use multiports when possible to

serve side streets• May need several design iterations to find optimum cable paths

– Balance or optimize fiber counts– Adjust access points as necessary– Utilize street crossings for both cables and multiport tails

• Upsize cable counts with spare fiber


Cable Placement – Branch Splicing from Main Cable

LCP

72-F cable

48-F cable

96-F cable

Need 288 fibers288-F cable

72

48

96

Need 72 fibers


Cable Placement – Using Multiple Cables

LCP

72-F cable

48-F cable

96-F cable

48

Need 72 fibers

144-F cable (120 fibers needed)


Changing Cable Counts

• In long length of cable(s), when to splice in smaller fiber count versus keeping larger count running

• When extra cost of higher count cable is less than splice point cost, it is better to keep higher count cable going

LCP

288-F cable

144-F cable2000-ft

132 fibers to be utilizedIn cable

Splice point


Cable Fiber Count Selection – Downsizing Fiber Counts

Keep higher count cable going when

(Chigh – Clow) x L < (N x Csplice) + S

Where Chigh = per foot cost of high count cableClow = per foot cost of lower count cableL = length of low count cable path in feetN = number of splices required for low count cableCsplice = cost per splice S = any applicable splice set-up charge



Model costs:288-F cable - $2.60 / ft144-F cable - $1.50 / ftPer splice - $35Splice setup - $150

Example Cable cost Splice cost

($2.60-$1.50) x 2000 ($35 x 132) +$150= $2200 = $4770

Splice cost is greater than additional cable cost=> keep large cable count running

288-F cable

144-F cable2000-ft

132 fibers to be utilizedIn cable

Splice point



Model costs:288-F cable - $2.60 / ft144-F cable - $1.50 / ft72-F cable - $0.80 / ft24-F cable - $0.60 / ftPer splice - $35Splice setup - $150

288-F cable72-F cable1700-ft

24-F cable1500-ft66 splices

22 splicesB

CLCP

Example - Splice point BCable cost Splice cost

($2.60-$0.80) x 1700 < ($35 x 66) +$150= $3060 = $2460

Additional cable cost is greater => splice in smaller count cable


Sample Design - Cable Paths


Convergence Point

• Local Convergence, Distributed Split architectures– Splitter management in field– Typical sizes range from 72 to 432 subscriber groupings– May be up to 864 for very dense neighborhoods

• Feeder fiber count and access of importance for future growth– Fibers that bypass splitter for businesses, future cabinets

• Included in cabinet or managed in splice closure– 1x32 split now may need to be 1x16 split later


Sample Design – LCP Placement


Design Considerations – Feeder (F1) Cable

• Central Switch Homerun architecture– High fiber counts needed– Low number of access points required

• Local Convergence, Distributed Split architectures– Low to medium fiber counts typically needed

• Spare fiber important– Revenue generation– Future cabinets, businesses, etc.

• Feeder should be highly protected cable– Installation considerations– Fast repair if damaged


Design Considerations - Central Switching Center

• Central Switch Homerun architecture– All homes directly connected, with or without splitters– Adds, drops, changes regularly required– Typically high density hardware requirements

• Local Convergence, Distributed Split, Segmented Split– Only splitter inputs connected– Medium to low density hardware requirements

• Mix of architectures– Some nearby homes may be served directly from CSC– Homes farther away served by local splitter cabinets

Thank you!Patricia AlsinaSystems Engineer IICorning Cable [email protected]

Documents

Design - Webinar Part 2