The interception of optical wireless systems operating with narrow beams in infrared spectral wavelength range is far more difficult. In fact, military organizations or government entities that rely heavily on extremely secure transmission technologies were among earliest users of optical wireless communication systems as a way to avoid signal interception. Therefore, it is understandable why study of FSO technology in military labs and security agencies dates back several decades. In early days of FSO development, ability to transmit information at high data rates was actually a less important factor than fact that FSO technologies offered one of easiest and most secure ways to exchange information between remote locations. The small diameter of beam of typically only a few meters in diameter at target location is one of reasons why it is extremely difficult to intercept communication path of an FSO-based optical wireless system: The intruder must know exact origination or target location of (invisible) infrared beam and can only intercept beam within very narrow angle of beam propagation. Even more difficult, intruder must have free and undisturbed access to installation location of optical wireless transceiver and be able to install electronic equipment without being observed. In majority of cases, installation location does not allow free access to a potential intruder because installation location is part of customer premise such as roof or an office (when optical wireless equipment is installed behind windows).

The direct interception of an optical wireless beam between two remote networking locations is basically impossible because beam typically passes through air at an elevation well above ground level. Due to fact that transmission beam is invisible and that any attempts to block beam would occur near optical wireless equipment terminus points, transmission process imposes another obstacle. Picking up signal from a location that is not directly located within light path by using light photons scattered from aerosol, fog, or rain particles that might be present in atmosphere is virtually impossible because of extremely low infrared power levels used during optical wireless transmission process. The main reason for excluding this possibility of intrusion is fact that light is scattered isotropically and statistically in different directions from original propagation path. This specific scattering mechanism keeps total number of photons or amount of radiation that can potentially be collected onto a detector that is not directly placed into beam path well beyond detector noise level

Summary Optical wireless communication systems are among most secure networking transmission technologies. Unlike microwave systems, it is extremely difficult to intercept optical wireless light beam carrying networking data because information is not spread out in space but rather kept in a very narrow cone of light. To intercept this invisible light beam, intruder must be able to obtain direct access to light beam. Due to very narrow beam diameter, interception of beam can virtually only be accomplished at customer premise where system is installed. At that point, it would be certainly easier for an intruder to plug directly into network by using existing copper-based infrastructure (e.g. unplug a CAT 5 networking cable and plug it into a laptop). Scattered light can not be used as a method of interception. Moreover, higher protocol layers can be used in conjunction with layer one optical wireless physical transport technology to encrypt sensitive network information and provide additional.

Source 2: Just 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 information age is to reach full realization. Although rural, suburban and metropolitan connections each have their own sets of challenges; metropolitan market is presenting greatest difficulty for true highbandwidth connectivity. Complete, efficient, and profitable networks to meet emerging customer needs cannot exist without creation of metro area connectivity using diverse medium and resources. While some may consider an all-fiber network ideal connectivity solution, 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 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 reach of metropolitan networks to network edge. This is same portion of network where regulation changes have encouraged telecommunications players to “race” to gain competitive advantage and deliver best value to customers

EVOLVING INFRASTRUCTURES Because metropolitan telecommunications network architectures—particularly those in 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, growth in bandwidth demands presents a different challenge, due to relative lack of network infrastructure.

TECHNOLOGICAL ADVANTAGES Optical wireless solutions and fiber are 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 same optical transmission wavelengths as fiber optics (850nm or 1550 nm). Second, optical wireless solutions and fiber can utilize 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 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 cost of fiber-optic cable and in one-tenth 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, 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 system to bridge to fiber network, providing optimal alignment between capital expenditure and income.

Complementary Future The future of 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 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 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 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 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 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 future of 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 capacity to enable true high-bandwidth communications. The network fiber backbone or “core” can carry bandwidth, but has yet to be connected to 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