Gigabit-capable Passive Optical Networks

2

SYSTEM REQUIREMENTS

In this chapter:

• Overview of power-splitting PONs
• Optical network considerations
  • Split ratio
  • Maximum reach, differential reach
  • PON protection
• Reach extenders
• Coexistence with future generations
• Types of ONU
• ONU powering
• Introduction to
  • Dynamic bandwidth assignment; details in Chapter 6
  • Quality of service; details in Chapter 6
  • Security; details in Chapter 4
  • Management; details in Chapter 5

Before diving into the details of how a G-PON works, we need to understand something about the business case. We return repeatedly to business case questions over the course of this book because, ultimately, everything we do must add value to someone for something.

As with most companies, telecommunications operators are driven forward by market opportunity, cost reduction, and competitive pressure, and they are held back by existing investment and existing practices. New technology is comparatively easy to justify in a greenfield development—we have to do something, so let us go for the latest and greatest!—but most of the potential market is already served in one way or another, even if it's no more than ADSL (asymmetric digital subscriber line) from a central office. The difficulty arises in making a business case for the deployment of a new technology that may be of immediate interest to only a small number of existing subscribers, in what is called, for contrast, a brownfield.

Civil works—right of way acquisition, permits, trenching for underground cable, poles ...