Advanced Fiber Access Networks

By Cedric F. Lam, Shuang Yin and Tao Zhang

Advanced Fiber Access Networks takes a holistic view of broadband access networks—from architecture to network technologies and network economies. The book reviews pain points and challenges that broadband service providers face (such as network construction, fiber cable efficiency, transmission challenges, network scalability, etc.) and how these challenges are tackled by new fiber access transmission technologies, protocols and architecture innovations. Chapters cover fiber-to-the-home (FTTH) applications as well as fiber backhauls in other access networks such as 5G wireless and hybrid-fiber-coax (HFC) networks.  In addition, it covers the network economy, challenges in fiber network construction and deployment, and more.

Finally, the book examines scaling issues and bottlenecks in an end-to-end broadband network, from Internet backbones to inside customer homes, something rarely covered in books.

• Provides the latest information on end-to-end broadband access networks, from architecture to network technologies and network economies

• Language: English
• Publisher: Academic Press
• Release date: Aug 11, 2022
• ISBN: 9780323855006

Cedric F. Lam

Cedric Lam was co-founder of Google Fiber which changed the landscape of broadband access networks in North America with the introduction of nationwide Gigabit FTTH networks. Cedric has experience both in product development and in engineering service provider networks. He started his career with AT&T and later joined Opvista, a startup company building high-capacity optical transport equipment, as chief system architect. After Opvista, he joined Google to work on datacenter networks before embarking the effort on Google Fiber, where he was Engineering Director, leading the Architecture and Device Engineering team. He is now Principal Engineer in Google’s Technical Infrastructure team, leading the development of datacenter network architectures and the development of network generation optical interconnects for datacenter networks. Cedric is a member of the CORD Technical Steering Team, and Fellow of Optica. He also edited the first textbook in PON: Passive Optical Networks, Principles and Practice, Academic Press, 2007.

Book preview

Chapter 1: Introduction

Abstract

This chapter discusses the trend, drivers, and history of the development of fiber access networks. It also compared fiber access networks to broadband wireless networks, a very hot topic in recent years. We also examined the energy efficiency of different types of telecommunications systems.

Keywords

Broadband access technologies; Fiber-to-the-home; Broadband wireless networks; Energy per bit; Energy efficiency; Network economy

1.1: Drivers and applications for broadband access

We live in an information society today where connectivity to data has become a utility like water and electricity to our modern human lives. Fig. 1.1 shows the annual growth of the Internet traffic between 30% and 37% from 2017 to 2022, as projected by the cisco VNI index [1]. Scalable, low-cost, and future-proof broad access infrastructure is key to the success in today's digital economy, promoting governments around the world to create strategies and policies to stimulate investments in broadband infrastructures and technologies, especially during economic downturns.

Fig. 1.1

Fig. 1.1 Global busy hour vs average hour internet traffic Ref. [1] .

The importance of broadband was amplified during the recent COVID-19 pandemic. After the global outbreak of COVID-19 in the beginning of the year 2020, in order to curb the spreading of the highly contagious coronavirus, people are requested to stay at home by the lockdown orders issued by governments around the world. The Internet has become the main avenue for people to work remotely from the home, take online lessons, consult with their physicians, stay connected with their loved ones, and buy food and necessities. Zoom, the maker of a popular video conferencing tool with the same name, saw a huge boom in their business and their stock prices rose through the stratosphere against a free-falling stock market. According to Ref. [2], the Internet traffic on EU (European Union) telecom operators grew 30% to 60% in the first 3 weeks since the lockdown. Fig. 1.2[3] shows the Internet data and traffic explosion after COVID-19. The prolonged COVID-19 pandemic will permanently change the way people work, play, and social, and the importance of the Internet will become even greater.

Fig. 1.2

Fig. 1.2 Data and traffic explosion after COVID-19.

Optical fiber was originally developed for long-haul transmissions. The idea of using fiber optic for access was initially proposed in the 1980s, way before the Internet and broadband access became the norm of our society. After decades of developments, fiber access networks are now mature technologies deployed to hundreds of millions of users around the world. In 2019, China alone boasted more than 395 million fiber-to-the-home (FTTH) users. Besides directly connecting residential households with FTTH networks, new forms of fiber access networks are indispensable in providing backhaul and fronthaul connectivities to the fourth generation (4G) and the upcoming fifth generation (5G) wireless networks.

Fiber access networks are deployed at the edge of telecommunication networks as end nodes. There are two major challenges in deploying fiber access networks. First, access networks are very cost sensitive, so the equipment cost has to be very low in order for it to be viable as a mass-deployed technology. The ways to achieve this are economy of scale and low-cost optoelectronics packaging techniques. The second major challenge in deploying fiber access networks is labor cost, and speed and ease of deployments [4]. Significant civil engineering cost is incurred especially in developed economies where (1) the labor cost is high, and (2) digging and trenching of infrastructure is not easy. Therefore, traditional incumbent carriers in developed nations would like to preserve their legacy copper infrastructure and delay the deployment of fiber in the last mile (from the central office) as much as possible. In developing economies or green field scenarios, there will be fewer architecture constraints, less legacy burdens, and more flexibility in technology and architecture choices. But those economies are also very capital cost sensitive and would like to leverage the low cost of existing, mature, and standard-based technologies. These challenges are guiding the design principles of fiber access technologies.

Broadband Internet access discussed earlier was the initial driving force for FTTH fiber access technologies. This was mainly propelled by the booming Internet applications, especially over-the-top (OTT) video streaming applications which offers any time and any place viewing experiences of on-demand contents. Higher resolution videos such as 4 K will demand more bandwidths to end users, mainly in the downstream direction from carrier networks to the end users. New applications such as teleconferencing and high-resolution video surveillance will also command high uplink return bandwidth from end users to carrier networks and will affect the architecture of fiber access networks. For example, during COVID-19, many people worked from home. Broadband access networks with limited upstream bandwidths, such as DOCSISa[5], would suffer from upstream bandwidth contention. People joining video conferences from DOCSIS cable modems often have poor image and/or sound quality due to the upstream access bandwidth contention. This was observed in a video conference among the first and second authors of this book and the publisher in England. The first author and the publisher were on FTTH access network, and the second author was on a DOCSIS cable network. During the teleconference, at the first author's terminal, the image of the publisher from London comes out crystal clear while the image from the second author who lived 20 miles away was very blurry. However, at the second author's terminal, the images from both the first author and the publisher were crystal clear because he had no downstream bandwidth problem. This is illustrated in Fig. 1.3.

Fig. 1.3

Fig. 1.3 The low upstream bandwidth from Author 2 causes his image to be blurred at Author 1 and Publisher while he perceives both Author 1 and Publisher as crystal clear.

One of the purposes of this book is to understand how to scale the overall end-to-end broadband fiber access network from an overall system perspective. FTTH was mainly provided by passive optical networks (PONs) [6]. In fact, PON is almost used as a synonym of FTTH although other FTTH implementations also exist. Most of the deployed residential FTTH networks are based on the IEEE 802.3ah EPON or ITU-TG.984 based G-PON technologies, with the latter being the most popular nowadays.

1.2: History and roadmap of broadband access development

Fig. 1.4 plots the peak bit rate of PON vs wireless (Wi-Fi and cellular) over the past four decades. Tables 1.1 through 1.3 summarize the major technology standards and peak data rate achieved by various generations of Wi-Fi, cellular, and PON systems. We can see from Fig. 1.4 that wireless access speed had a low starting point but is catching up very quickly (driven by the needs of both broadband applications and mobility). FTTH technologies, as represented by the PON speed development trends, are growing much more slowly, however. We are just at the point where fiber and wireless access speeds are converging. A detailed account of PON standards development can be found in