Gigabit-capable Passive Optical Networks

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INTRODUCTION

Fiber optic access networks have been a dream for at least 30 years. As speeds increase, as the disparate networks of the past converge on Ethernet and IP (Internet protocol), as the technology and business case improve, that dream is becoming reality.

The access network is that part of the telecommunications network that connects directly to subscriber endpoints. This book details one of the technologies for fiber in the loop (FITL), namely gigabit-capable passive optical network (G-PON) technology, along with its 10-Gb sibling XG-PON. Figure 1.1 shows how G-PON and XG-PON fit into the telecommunications network hierarchy. This book is about the G-PON family.

For quick reference, Table 1.1 summarizes the common PON technologies, including both the G-PON and EPON families. The G-PON family is standardized by the International Telecommunications Union—Telecommunication Standardization Sector (ITU-T), while EPON comes from the Institute of Electrical and Electronic Engineers (IEEE). Chapter 7 includes a comparison of G-PON and EPON.

Because they share many properties, this book uses the term G-PON generically to refer to either ITU-T G.984 or G.987 systems unless otherwise stated. Where a distinction needs to be made, we make it explicit: G.984 G-PON or G.987 XG-PON.

Figure 1.2 illustrates the fundamental components of a PON. The head end is called the optical line terminal (OLT). It usually resides in a central office and usually serves more than one PON.* The PON ...