Bridging the optical dead zone with free-space optics

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Metro Networks

Free-space optics provides an economical metro-access alternative where wireless and conventional fiber optics fall short.

BAKSHEESH S. GHUMAN, LightPointe Communications Inc.

Free-space optics (FSO) is an optical technology-let there be no doubt about that. FSO also is a simple concept. It involves the transmission of voice, video, and data through the air using lasers. FSO has been deployed successfully for more than two decades. It's not a disruptive technology; it's more of an enabling technology that promises to deliver that ever-elusive high-speed optical bandwidth to the ultimate end users.

The technology of FSO is very similar to fiber optics, except the medium is air instead of fiber. However, FSO offers many advantages when compared to fiber. Its deployment requires a fraction of the time and cost of conventional fiber networks, allowing carriers to generate revenue quickly while taking advantage of the high capacity of optical transmission. FSO allows service providers to accelerate their deployment of metro optical networks as well as extend optical capacity to anyone who needs it. It also represents a zero sunk-cost solution. As opposed to fiber, FSO can be redeployed if your customer moves or cancels service.

In addition to providing service without the need to dig trenches, FSO also obviates the need to buy expensive spectrum (and thus requires no FCC or municipal license approvals), which distinguishes it clearly from fixed wireless technologies. Thus, FSO should not be classified as a wireless technology. Its similarity to conventional optical solutions will enable a seamless integration of access networks with optical core networks and help to realize the vision of an all-optical network.

As the growth in end-user needs for immediate high bandwidth outstrips network deployments, service providers find themselves stranded. They are stranded both in terms of invested capital and invested resources, without the expected and necessary revenues to support those investments. Further aggravating this challenge is increasing competition. Service providers must alleviate capital concerns and identify tools that will allow them not only to stay ahead of the competition, but also remain in business.

FSO technology meets a variety of carrier needs. For example, FSO equipment is simple and easy to install. That allows metro service providers to acquire target customers very quickly in comparison to fiber installs. Easy upgrades will allow service providers to retain customers as their bandwidth requirements change (no forklift upgrades). Similarly, FSO products allow carriers to gain significant leverage in their capital by lowering the cost of "wiring" buildings for high-bandwidth access. That allows them to gain an acceptable return on their capital investment with a lower rate of monthly telecommunications revenue.

FSO systems eliminate or avoid wasted capital. With FSO, service providers only have to deploy when they have customers. This "build as they come" model allows service providers to deploy infrastructure only once a customer is acquired. This offers better alignment between capital expenditure and cash flows. Meanwhile, given the current market environment, service providers are looking to minimize their execution risk. They can now find FSO products that are field-proven and customer-deployed. The products are quickly and easily installed into any network.

This speed advantage becomes clear in light of the several-month average lead time to buy fiber and the six months it can take to obtain construction permits. FSO eliminates this bottleneck, while the technology's ease of installation and flexible reuse or redeployment (no forklift upgrades) eliminates the risk of stranding capital for fiber installation to a particular building. With service providers actively looking for a low-cost alternative to existing technologies to address ever-increasing price wars, FSO offers economical, high-bandwidth connectivity.

It is clear that is there is unprecedented growth in bandwidth usage, and there is no reason to believe the bandwidth explosion will slow down in the near future. A number of factors are influencing this bandwidth surge, particularly in metropolitan-area networks.

Substantial investments by carriers to augment the capacity of their core fiber backbones have driven dramatic improvements in both price and performance and substantially increased the capacity of these large backbone networks. To fully leverage these backbone investments and utilize this capacity, substantial bandwidth upgrades at the network edge are required. Essentially, higher-bandwidth connections must reach the end-customers to generate the communications traffic and revenue to fully utilize and pay for these backbone upgrades. Service providers will now need to expand and extend the reach of their metro optical network to the edge. FSO presents an opportunity that allows them to achieve that goal for one-fifth the cost when compared to fiber (if even available) and at a fraction of the time.

Meanwhile, regulatory changes and significant investments last year by various capital sources have increased the competitive climate in metro networks. Each existing or new entrant is "racing" to gain an advantage over its competition. FSO is one of the evolutionary technologies that allow a carrier to gain an edge over competition and acquire and retain new customers quickly and cost-effectively.

This new paradigm is not limited to the United States. Most countries around the world are experiencing tremendous growth in bandwidth needs due to the growing number of Internet-based applications. In growing economies like Latin America, China, and India, the lack of infrastructure and the rising bandwidth demands offer a unique opportunity for FSO. Requirements for reliability and availability may not be as high as in the United States but the ability to have high-bandwidth connectivity remains appealing.

Regardless of their location around the world, metro networks are characterized by multiple traffic types. Where voice was once the dominant traffic type, now data has emerged as the winner. Moreover, the networks are also a mixture of multiple protocols, including Ethernet, SONET/SDH, Internet Protocol, Escon, Ficon, etc.

Finally, despite the rapid adoption of wireless technologies such as LMDS and MMDS in response to high-bandwidth communication needs in the metro area, deployment of these options remains slow. Thus, many service providers still find themselves short of bandwidth to satisfy all needs. FSO offers service providers an alternative to address that need at a fraction of the cost.

As mentioned, FSO has existed for decades, with its primary use in secure military communications with varying spans. But FSO has now found commercial viability.

There are many factors that can be attributed to this phenomenon, but following are the main factors:

  • Cost-effectiveness of an FSO solution.
  • Minimal capital investment.
  • High-bandwidth applications on the rise.
  • Global optical infrastructure on the move.
  • Flexibility.
  • Lack of fiber (infrastructure and supply).
  • Ease of deployment and redeployment.
  • High-speed optical technology.

Based on these factors, FSO use will grow both in North America and globally, with the majority of the growth happening outside of North America (see Figure 1). Asia (particularly China, India, and Southeast Asia), Latin America, and Europe will lead the way because of a general lack of infrastructure, the fact that city authorities are less likely to allow service providers to dig up congested streets, the need to have services up quickly, less stringent availability requirements, more densely populated metro areas (more buildings and hence shorter distance spans), and the general unavailability of bandwidth. Th 06lwspr01fig1

Figure 1. The majority of growth in the free-space optics market will occur outside of North America. Yet, the technology can benefit markets across the globe.

In contrast, the pressure faced by service providers to acquire more customers, generate revenue quickly, and offer services cost-effectively will drive FSO growth in North America.

To better understand this need for FSO, it is important to understand the key drivers for this technology. These drivers include market, economic, service, business, and environmental factors.

For example, the market has seen the Internet create a great need for high bandwidth at the edge of the network. The number of Internet users is expected to grow to about 796 million by 2005. The growing number of businesses involved in business-to-business activities has led e-commerce to represent a salient example of this high-bandwidth requirement. Meanwhile, with multimedia and exponential increase in processor speeds, the desktop computer is now an enabler of high-bandwidth applications, as well. To meet this huge increase in bandwidth, service providers must offer high-bandwidth access at the edge of the network.

Thus, service providers are investing millions of dollars in deploying DWDM-based metro optical networks as a direct result of the increase in bandwidth usage at the edge. Service providers are now faced with mounting pressures to speed up this deployment and at the same time generate revenues. FSO meets both needs.

The fact that early networks were developed to meet the needs of the core and the majority of commercial buildings were constructed in the early 1980s means most buildings do not have high-speed access. FSO provides a quick, cost-effective, and reliable means to address the needs of those users.

Market factors also favor FSO over wireless technology. MMDS/LMDS approaches carry the high cost of acquiring spectrum and the time needed to build such networks, along with the fact that such systems need to be linked to each other and the PSTN. At the same time, spectrum scarcity, coupled with bandwidth appetites in metro networks, is forcing wireless operators of 3G and 4G networks to look at new methods to connect cells. FSO offers a viable option.

Several economic drivers also support the deployment of FSO. For example, with costs that are considerably lower than traditional equipment, FSO offers service providers the opportunity to reduce costs immediately. Quicker provisioning intervals speed up the service activation time for service providers to turn up services, thus generating revenue quickly. FSO offers a broad range of speeds (20 Mbits/sec to 2.5 Gbits/sec) scalable within a matter of hours to meet customer needs. Unlike traditional SONET/SDH boxes, FSO does not require large amounts of money to store additional line cards.

Using FSO products, service providers also can offer multiple services (Gigabit Ethernet, Fibre Channel, Escon, etc.) from the same platform, due to the inherent transparent core of the product. And easy installation and quick deployment makes FSO products invaluable tools to acquire market share rapidly.

In the services sector, there is an increasing demand for high-speed access interfaces. Thus, the interface flexibility just discussed is highly desirable. FSO will be able to meet this increasing demand for high-bandwidth applications quickly and cost-effectively.

FSO also helps avoid situations in which the network edge and core work against each other. With DWDM, and wavelengths operating in the 1,550-nm range, service providers will be able to integrate metro optical networks with FSO networks. The technology also promotes network simplicity. Fewer moving parts mean fewer points of failure and fewer elements to manage. Finally, with changing customer needs and unpredictable traffic patterns, service providers need the ability to provision on demand. FSO provides them with this flexibility.

Business drivers that support FSO deployment include the ability to help service providers accelerate and extend their metro optical networks to the end user. It also supports customer retention, offering a tool that helps service providers stay competitive and ahead of competing technologies.

To globally compete with other services and services providers, variable SLAs are a value-add for many service providers. Variable SLAs offer varying levels of customer satisfaction. With FSO, service providers can choose to offer SLAs for each deployment in each geographic location.

With growing economies around the world, many countries use equal or more bandwidth than North America. This shift has created a definite need for a high-bandwidth platform. FSO offers a unique opportunity with its license-free capacity, along with its low cost, to meet those emerging needs.

Finally, environmental drivers also favor FSO. Digging streets to lay fiber causes traffic jams in major cities and contributes to pollution. Also, some cities recently have reported broken water mains due to prolonged digging, adding further to pollution problems. With FSO, you do not have to dig up streets and add to the pollution. In some older communities, digging up streets may mean destroying historic landmarks that may never be recovered. Trenching fiber also can lead to the removal of trees. With FSO, it is not necessary to disturb or destroy the ecosystem, thus preserving the natural balance.

With the understood need for high bandwidth at the network edge and the unavailability of a viable alternative, FSO will undergo a period of gradual deployment, as it faces the adoption challenges common to any new technology. It is valuable to understand the FSO adoption cycle.

It is important to note that the migration of FSO is clearly from the enterprise market (global) to competitive local-exchange carriers (globally) to regional Bell operating companies (RBOCs), and finally to the residential markets. The leaders in the FSO market are currently at the carrier-adoption phase, having proved the technology successfully at the enterprise level with customers and deployments. To move ahead and successfully prove the product to carriers, the FSO vendors need to incorporate certain features in their product line:

  • Flexible range of bandwidth. The ability to meet the whole spectrum of bandwidth needs (20 Mbits/sec to 2.5 Gbits/sec and higher).
  • Flexible range of transport distances. An important factor, as it determines the possible applications (200-4,000 m).
  • Transport-protocol "agnostic," enabling carriers to seamlessly integrate FSO with their existing infrastructure.
  • Flexible geometry (rooftops, windows, combinations), ensuring options for places where roof rights are an issue and offering choices for flexibility of deployment.
  • Standard network-management interfaces.
  • Weather management.
  • Scalable link reliabilities to 99.999%.
  • Compliant with all eye safety and environmental standards.
  • Superior product design for performance in diverse atmospheric conditions.

Armed with such features, FSO will become a part of the carrier toolbox, thus finding its way into many a carrier applications, be it last mile, metro-network extension, network redundancy, or an optical gap filler wherever high capacity is needed quickly and cost-effectively. Once FSO migrates into the core network, it clearly enters the FSO "shift zone" (see Figure 2).Th 06lwspr01fig2

Figure 2. Like any new technology, FSO faces an uphill climb in its quest to become a mainstream technology. This goal will be reached when enough competitive and international carriers adopt the technology and it begins to appear in the network core. At this point, the emphasis "shifts" to incumbents such as the regional Bell operating companies, which will feel the competition as well as end-user pressure to adopt the technology.

The FSO shift zone is clearly the point where FSO becomes mainstream. Standards begin to become important and RBOCs feel pressure to start deploying FSO in their networks while developing a global support infrastructure ensuring interoperability and integration with their systems. Innovation will drive prices down and further drive the application closer to the ultimate end user, and if forecasts are correct, that end user will be the ultimate driver of high-bandwidth applications.

The optics market is growing and forecasted to hit $57.3 billion by 2005. This market has been growing not only in the number of companies and competition, but also in technology adoption and deployment.

While some service providers are leading this race, others are slow to start. Why? Not because they lack speed, but because the infrastructure necessary to accelerate such deployment is not yet available. Lead times for fiber range from a few to several months, and many service providers have less capital to buy fiber or make long-term commitments to invest in fiber. Meanwhile, the billions of dollars spent to lay fiber infrastructure is underutilized and essentially stranded, which has created a bottleneck in the broadband network-an "optical dead zone."

But with FSO, "acceleration," not "stranded," is the operative word. FSO enhances and extends metro optical networks at a fraction of the cost of traditional fiber-and, more important, at a fraction of the time. FSO allows metro optical networks to reach the end users optically much sooner than previously possible, thus bridging this optical dead zone.

FSO is not limited to the last mile. Instead, the technology is an enabler of optical networking. It can play a role in the core, edge, or access, addressing segments such as the last mile, enterprise/

LAN, or metro-network extension, network redundancy, Gigabit Ethernet applications, etc. It is flexible, offers freedom, and is fast. Imagine all the places where barriers (variable of costs, time, and infrastructure) prevent a service provider from offering optical services. FSO offers a cost-effective, quick, and available infrastructure that is not only easily deployed (within hours), redeployed, and easy to manage, but can also offer a multitude of options (distance, speed, topology, and installations). And FSO can do all of that with carrier-class reliability, availability, and flexibility.

Demand for bandwidth has increased exponentially for the past few years. Service providers have struggled to keep up with such demand, and DWDM is being used to meet that need. There is a tremendous effort underway to upgrade the core, but the same effort has not been made for end users. In fact, end users, in many cases, feel abandoned. With all the bandwidth that will be available in the metro core, service providers must find a way to reach the end users. Service providers must extend the reach of metro optical networks, and FSO offers service providers the opportunity to do so.


Baksheesh S. Ghuman is vice president of marketing at LightPointe Communications Inc. (San Diego).

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