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Terawave Communications, Inc. Network Planning Course Module 3 PON Physical Network Engineering. Objectives. At the end of this module, you will: Understand the types of engineering required for a PON network
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Terawave Communications, Inc. Network Planning Course Module 3 PON Physical Network Engineering
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
Contents • Engineering Requirements – 4 • Splitters – 7 • Optical Power Levels & Receiver Sensitivity – 11 • Fiber Characteristics – 14 • Delay Requirements – 16 • The PON Planning Tool – 19
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
Engineering RequirementsPhysical Network Topology • PON basics • Optical power levels • Splitter information • Type • Losses • Placement • Fiber • Type • Loss characteristics • Distances • Delay requirements
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
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
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
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
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
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
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
The PON Optical Budget WorksheetAdvance Information Required • Fiber Attenuation • Splitter Loss • Fiber Routing • Fiber Distances • Customer Locations
The PON Optical Budget WorksheetOverview • 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
The PON Optical Budget WorksheetFiber 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
The PON Optical Budget WorksheetFiber 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
The PON Optical Budget WorksheetSplitter 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
ObjectivesRevisited • 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
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