Introduction
Amid the pervasive talk about the promises of the information
economy, it’s easy to overlook the logistical challenges of
delivering the necessary infrastructure to ensure everyone who
wants connectivity is connected—regardless of where they live.
Projected growth in customer demand for bandwidth will go
wanting without connectivity, and the real challenge for fully
realized networks is to create connections despite the very real
physical and economic obstacles presented by today’s modern
cities. The rewards for providing these connections are the
likelihood of recouping previous investments in the fiber-optics
network core/backbone—and establishing customer reliance on
high-bandwidth networks for continued economic growth.
At one point, many telecommunications industry leaders and
technology observers dreamed of all-fiber networks. But this
vision is impractical for several reasons. The process of laying
fiber in cities is time-consuming and often prohibitively
expensive. Ongoing preservation and restoration of fiber-optic
systems in the event of accidental disruptions or natural
disasters is also time-consuming and technically challenging, as
service providers must address the concerns of bandwidth
dependent customers frustrated with every hour of lost network
access.
That having been said, all-optical fiber-optic networks—with
their high-bandwidth capacities—are promising. Still, a world
complete with fiber connections for all is decades from reality.
Deciding how best to complete high-bandwidth connections across
networks is one of the great quandaries of the information age,
and choosing which technologies to deploy to complete network
connections will depend on costs and reliability(1) A
combination of high-capacity access technologies provides the
most cost efficient and reliable solutions for addressing both
primary connections and backhaul. For all-optical networks,
fiber optics and optical wireless solutions are the only two
technology choices.
(1) Source: Free Space Optics, Merrill Lynch Global Securities
and Economics Group, 15 May 2001
Parallel Histories
It may seem to telecommunications carriers and industry analysts
that FSO technology only recently appeared, like a beam of
light, to the optical communications landscape. But FSO is only
new in one respect: as a market proven technology for optical
wireless solutions that provide customer connectivity in private
and public networks spanning more than 60 countries.
FSO technology itself is older than fiber optics. Technically,
optical communications includes all forms of communications
using light, including mirror signals and lighthouses, offering
a rich and storied history.
The electrically powered optical technologies referred to by the
term “optical” or “electro-optical” began with the introduction
of the laser in 1960, which enabled the transmission of digital
information as pulses of light.
FREE-SPACE OPTICS
Recent developments in FSO technology target telecommunications
improvements for Metropolitan Area Networks (MANs), but the
technology has its roots in government applications dating back
to World War I when military units and covert agencies needed
secure communication systems that did not require cable and
could withstand intentional interference, also known as “radio
jamming”. Portability of these early FSO devices was a hallmark
and made them particularly valuable to military personnel who
needed secure communications equipment that was simple to set
up, transmit information and move from location to location.
Additional optical communications developments occurred during
World War II, and post-war economic restructuring led to further
telecommunications technology progress. While electronics
innovations such as the transistor and integrated circuits
enabled post-war telecommunications progress, the laser’s
launching of electro-optical communication fueled research and
development of advanced optical communications using the only
medium for laser transmission available then to military and
aerospace industry physicists: the atmosphere, or “free space,”
hence the term free-space optics. Research and application of
free-space optics continues to thrive in the aerospace industry
to this day for applications beyond commercial and private
telecommunications networks. Today’s commercially deployed
optical wireless solutions are the result of a culmination of
FSO technology advancements.
FIBER OPTICS
After 1970, the introduction of the fiber-optic cable as optical
transmitter—along with the establishment of digital
technology—combined to usher in a worldwide telecommunications
revolution. Key among fiber’s attributes is its immunity to
electrical interference (no electricity is run through the
fibers, so fiber signals do not interfere with each other);
therefore, fiber can be run in areas without regard to
interference from electrical equipment. Other benefits of fiber
are:
• Security. It is resistant to taps and doesn’t emit
electromagnetic signals.
• Compact size. Less duct space is required for these
hair-strand sized fibers.
• High-bandwidth capabilities and low attenuation. Less fading
or weakening of signals occur over long distances, which means
fewer amplifiers are needed to boost the optical signals.
Given these advantages, fiber-optic cable held the promise of
revolutionizing the telecommunications sector, which was eager
to build the initial fiber networks.2 The first practical fiber
systems were deployed by the telephone industry in 1977 and
consisted of multimode fiber. Single-mode fiber, a more recent
development, was first installed by MCI in a long-haul network
system that went into service in 1983.3 The result of
fiber-optic cable deployment is an extensive network of fiber
crisscrossing the land. During the 1990s, the telecommunications
network capacities grew nearly 10 times as much as the traffic
itself, with most of the bandwidth concentrated in dark fibers
along the network backbone often inaccessible to the end-user.5
The massive investment to put optical capacity in the long-haul
telecommunications network backbone looks relatively simple
compared with today’s metropolitan network challenges.
Beginning in 2000, carriers intensified their focus to building
fiber-optic cable connections between the United States’ 25
largest metropolitan areas to the nation’s long haul backbone
networks. This network gap is often called the “last mile,”
where only 7 percent to 10 percent of end-users have access to
fiber. “Routes in cities typically run to incumbent telephone
company central offices and carrier hotels, which often are
clustered together in the same areas, frequently near AT&T’s
switches.
>From there, they have runs to customers, data centers, Internet
service providers and application service providers.”5 While
this network configuration sounds relatively simple, the
logistics of laying fiber connections in metropolitan areas are
quite complicated and time-consuming. The expense of
construction and right-of-way permits for laying fiber often
amounts to 20 percent of the cost of building fiber routes for
networks. Moreover, the convoluted process of obtaining permits
can delay projects for 12 months to 16 months or longer.
Metropolitan landscapes, with their busy streets, politically
powerful neighborhoods, historic districts, and public works
bureaucracies make the permit process more complex to navigate
than those in suburban and rural long-haul network routes.6 Time
delays can be created by municipal public works departments
whose staff members feel a responsibility to protect public
investments in road surfaces, water mains and gas lines, plus
quality of life concerns regarding noise, dust and traffic
disruption during construction projects to lay fiber.
Source 2: Just the Facts, Corning Incorporated, 1995 Sorce 3:
The Essential Guide to Telecommunications, Annabel Zodd, 2002
Source 4 What Ever Happened to Broadband?, Erick Schonfeld,
Business 2.0, October 2002 Source 5: The Essential Guide to
Telecommunications, Annabel Zodd, 2002 Source 6: Can They Dig
It?, Kate Gerwig, Teledotcom, March 2001
Today’s Emerging Synergistic Optical Wireless/Fiber Landscape
>From rural farms to suburban hospital campuses to big city
high-rise offices, high-speed network connections must be made
available everywhere people live and work, if the information
age is to reach full realization. Although rural, suburban and
metropolitan connections each have their own sets of challenges;
the metropolitan market is presenting the greatest difficulty
for true highbandwidth connectivity. Complete, efficient, and
profitable networks to meet emerging customer needs cannot exist
without the creation of metro area connectivity using diverse
medium and resources. While some may consider an all-fiber
network the ideal connectivity solution, the medium’s
high-bandwidth capacity comes at a high price that is not
feasible everywhere. A number of compelling factors justify
further integration of optical wireless solutions to complement
fiber deployments to meet the growing connectivity demands.
Service providers that have invested significantly to build
network fiber backbones now need communications traffic to fully
utilize network upgrades and generate revenues to pay for such
investments. Developing metro optical network deployments
(substantial bandwidth upgrades) extends the reach of
metropolitan networks to the network edge. This is the same
portion of the network where regulation changes have encouraged
telecommunications players to “race” to gain competitive
advantage and deliver the best value to customers
EVOLVING INFRASTRUCTURES Because metropolitan telecommunications
network architectures—particularly those in the United States
and Western Europe—have evolved as a patchwork of technologies,
communications data is often slowed by protocols translations to
manage and direct high-bandwidth information through metro
networks. In growing economies such as China, India and Latin
America, the growth in bandwidth demands presents a different
challenge, due to relative lack of network infrastructure.
TECHNOLOGICAL ADVANTAGES Optical wireless solutions and fiber
are the two optical technologies today that deliver high-speed
optical bandwidth to meet market needs. Their integration offers
several technological advantages. First, fiber optics and
optical wireless solutions share several characteristics.
Optical wireless solutions can use the same optical transmission
wavelengths as fiber optics (850nm or 1550 nm). Second, optical
wireless solutions and fiber can utilize the same system
components such as lasers, receivers and amplifiers. Third, both
fiber and optical wireless can transmit digital information
using a range of protocols. Fourth—and critically important in
meeting technological demands—optical wireless delivers the
bandwidth (up to 2.5Gbps) necessary to complement fiber networks.
STRONG BUSINESS MODEL The business advantages of optical
wireless for network extensions include deployments at an
average of one-fifth the cost of fiber-optic cable and in
one-tenth the time. Optical wireless systems are a flexible
investment that can be re-deployed to meet changing customer
needs. Optical wireless and fiber also integrate seamlessly, and
because optical wireless equipment is simple and easily
installed, the technology can bridge optical network gaps
effectively with reduced CAPEX risk. Installing optical wireless
solutions to complement fiber enables service providers to
secure customers in a specific location first before installing
the system to bridge to the fiber network, providing optimal
alignment between capital expenditure and income.
Complementary Future The future of the information economy
depends on profitability. Despite large debt loads and low cash
flow, service providers cannot afford to forego investments
necessary to grow their customer base—and that requires
extending their networks to complete “last mile” connectivity.
Now that they are being more discriminating about the way they
spend their money, service provider managers are demanding
high-bandwidth technologies that will also lower OPEX. Flexible
networks that can adjust to changing customer concentrations and
metro environments are needed. Combining optical wireless and
fiber to create optical networks offers the best solution to
these problems. The reward for successfully combining these two
optical technologies is attainable and economically viable.
Complementary deployment of optical wireless and fiber serves
the needs of a variety of carrier types in metropolitan
networks. Market growth for both last mile access and network
extension applications is predicted to experience a 219% growth
rate in 2001 over 2000 and has the potential to extend metro
last-mile networks.7 Despite questions about economic growth,
there is no reason to expect that customer demand for bandwidth
will slow in the near future, and although carrier capital
spending may have slowed to a crawl, prospects for growth remain
strong.8 SG Cowen projects carrier spending on new equipment,
after two years of decline, should hit $102 billion by 2003.
Metro optical networks are expected to see $57.3 billion
invested by 2005.
Conclusion The most exciting possibilities for the future of the
information economy will only be practical and profitable when
network connectivity is expanded to reach a broad customer base.
Telephone lines have this connectivity, but they don’t offer the
capacity to enable true high-bandwidth communications. The
network fiber backbone or “core” can carry the bandwidth, but
has yet to be connected to the majority of potential users. A
new paradigm for building optical networks offers an alternative
to expensive and timeconsuming fiber-only metro networks. By
combining optical wireless and fiber, networks can be built
quickly and provide affordable and scalable connections to
end-users, who are expected to continue increasing demand for
bandwidth.
Source 7: The Strategis Group, Free Space Optics: Global Trends,
Positioning, and Forecasts, September, 2001 Source 8: Optical
Networking Industry, SG Cowen Securities Corp., August 2001
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