1 module 3 terawave confidential – do not copy terawave communications, inc. network planning...
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Terawave Communications, Inc.
Network Planning Course
Module 3 PON Physical Network Engineering
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Objectives
At the end of this module, you will: Understand the types of engineering required for a PON network Understand how the engineering relates to the Kingston
Communications network Understanding the PON Planning Tool
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Contents
Engineering Requirements – 4 Splitters – 7 Optical Power Levels & Receiver Sensitivity – 11 Fiber Characteristics – 14 Delay Requirements – 16 The PON Planning Tool – 19
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Engineering Requirements
Network planning can be broken down into two areas: Physical Network Topology – Designing the physical configuration of
the network
• PON
• INT Traffic Engineering – Planning for the services to be supported on the
network. These services can also drive the design of the physical network topology
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Engineering Requirements
Physical Network Topology
PON basics Optical power levels Splitter information
Type Losses Placement
Fiber Type Loss characteristics Distances
Delay requirements
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Splitters
Optical splitters are manufactured by a number of different vendors
The uniformity of the insertion loss across the splitters is dependent upon: Manufacturer’s tolerances Manufacturer’s processes
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Splitters
Splitters are manufactured in a variety of combinations Most commonly used in a PON network are splitters
with a single input and multiple outputs. 1x2 splitters (1 input, 2 outputs) are manufactured in a
multiple formats with respect to how much of the optical power is send out each leg
1x3 to 1x32 splitters are all manufactured so that the optical power is uniformly split among all the output legs
Because the manufacturing process and quality control is different for each manufacturer, refer to the manufacturer’s specs for the splitters to determine the insertion loss across each output leg of the splitter
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Splitters
Split Ratio Insertion Loss
1x2
95/5
90/10
80/20
70/30
60/40
50/50
-0.5/-14
-0.8/-11.2
-1.3/-7.6
-2.0/-6.0
-2.4/-4.3
-4.0/-4.0
1x3 -5
1x4 -6.25
1x8 -9.25
1x12 -10.75
1x16 -12.5
1x32 -15.5
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Optical Power Levels & Receiver Sensitivity
In the network design process, it is important to know the output optical power levels and receiver sensitivity of each device
Optical transmitters on low end devices will vary. Thus, the output optical power levels is provided as a range, typically from the highest to lowest level
The link budget for a Terawave PON is determined by subtracting the lowest output optical level of the transmitting device from the receiver sensitivity of the receiving device
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Optical Power Levels & Receiver Sensitivity
Card Optical Output Power Level
Receiver Sensitivity
PCU, 622 +3dBm to –3dBm -11dBm to –33dBm
PAU, 622, ETSI +3dBm to –2dBm -8dBm to –27dBm
NAU, STM-1 -8dBm to –15dBm -8dBm to –28dBm
NAU, OC-3 -8dBm to –15dBm -8dBm to –28dBm
NIM, STM-1 -8dBm to –15dBm -8dBm to –28dBm
NIM, OC-3 -8dBm to –15dBm -8dBm to –28dBm
NIM, STM-4 -8dBm to –15dBm -8dBm to –28dBm
NIM, OC-12 -8dBm to –15dBm -8dBm to –28dBm
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Fiber Characteristics
Terawave PON products have been designed to work with single mode fiber
The fiber manufacturer that Terawave has tested extensively with is Corning
The characteristics of Corning SMF-28 are the fiber characteristics that Terawave takes into account when testing for: Refraction Absorption Scattering Back-reflection
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Delay Requirements
Not all applications are delay sensitive Data applications are typically NOT delay sensitive
Computers have patience (and buffers) and can wait for data
Visual or Audible applications traditionally ARE delay sensitive Video signals normally requires a fairly constant flow of information to
provide a clear, non-jerky picture
• Recent advances in compression technology allow the flow of information to vary dependent upon the changes that occur from frame to frame
Traditional audio signals (TDM) normally require a fairly constant flow of information to provide a clear signal, irregardless of whether a party is talking or not
ATM technology allows transmission of an audio signal only when a party is speaking. Resulting in an uneven flow of traffic, but still a clear audio signal This is AAL2
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Delay Requirements
If an application is being provisioned that is sensitive to delay, you must be conscious of the path that the connection takes so the delay is minimized This is most applicable to INTs that are daisy-chained In PON networks, delay is automatically minimized by the network
structure
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The PON Optical Budget Worksheet
The PON Planning Tool is a “homegrown” application developed by a Terawave Sales Engineer to assist Terawave customers in planning the physical network topology of a PON
The Tool is a Excel application Some information is required to be obtained in advance
for entry into the Tool
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The PON Optical Budget Worksheet
Advance Information Required
Fiber Attenuation Splitter Loss Fiber Routing Fiber Distances Customer Locations
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The PON Optical Budget Worksheet
Overview
Very brief, high-level, instructions are provided in Worksheet #1
Parameter explanations are provided in Worksheet #5 Worksheets 2 thru 4 are provided for the different
topologies supported by the PON system
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The PON Optical Budget Worksheet
Fiber Information
The left side of the Tool is locked and stationary and provides the user with the ability to enter specific
information about the fiber and the splitters being used in the network
It also provides information about the OLT OLT Tx Power is worst case value OLT Rx Sensitivity is worst
case value
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The PON Optical Budget Worksheet
Fiber Attenuation
These information fields are located in the upper left corner of the Worksheet
The information entered here is dependent upon the individual fiber systems and the quality of the fiber plant, whether splices are fusion or connectorized, cleanliness of fibers, etc, etc.
It is recommended to leave these values at the default unless specific knowledge is known that forces a change. These values are typical of a fairly new or well maintained network
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The PON Optical Budget Worksheet
Splitter Loss
This information field is located in the upper left corner of the Worksheet
This information is obtained from the manufacturer’s specifications The numbers provided by the manufacturers is usually theoretical
since splicing of fibers is not an exact science and specific values cannot be guaranteed.
Some manufacturers will provide test results with each splitter specifying the loss on each leg, but this is not normal
The Tool will operate in a conservative manner when calculating the splitter loss values
Prior to deployment of a PON based on this Tool, all values should be manually checked
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Objectives
Revisited
Understand the types of engineering required for a PON network
Understand how the engineering relates to the Kingston Communications network
Understand the PON Planning Tool