| -link"> | | | | intruder can easily intercept the beam or power |
| | | | reflected from the target location and pick up |
| Introduction | | | | sensitive network information by using a |
| Network security is one of the major concerns | | | | spectral scanner tuned tothe specific RF or |
| for any business or organization transporting | | | | microwave transmission frequency. To overcome |
| sensitive and confidential information over the | | | | these security concerns, the microwave industry |
| network. Such network security concerns involve | | | | uses wireless encryption protocols (WEP) to |
| the lowest network layer, typically referred to | | | | protect the transmission path from being |
| asthe physical layer (layer one), as well as higher | | | | intercepted. Although it is extremely unlikely that it |
| software layers of the networking protocols. Most | | | | is possible to break into a sophisticated encryption |
| of the interception activity by outside intruders | | | | code, there is always the concern that it can be |
| occurs within higher protocol software layers. | | | | done. |
| Password protection or data encryption | | | | The interception of optical wireless systems |
| areexamples of counter measures to protect the | | | | operating with narrow beams in the infrared |
| network from outside and unwanted tampering. | | | | spectral wavelength range is far more difficult. In |
| Intrusion of the physical layer itself can be | | | | fact, military organizations or governmententities |
| another concern for network operators, although | | | | that rely heavily on extremely secure |
| it is a far less likely target for unauthorized | | | | transmission technologies were among the |
| accessto networking data. This can be a threat if | | | | earliestusers of optical wireless communication |
| information is transported over a copperbased | | | | systems as a way to avoid signal interception. |
| infrastructure that can be easily intercepted, but | | | | Therefore,it is understandable why the study of |
| optical wireless transmissions are among the most | | | | FSO technology in military labs and security |
| secure connectivity solutions, regarding network | | | | agencies dates back several decades. In the early |
| interceptionof the actual physical layer. | | | | days of FSO development, the ability to transmit |
| LightPointe’s optical wireless networking | | | | information at high data rates was actually a less |
| equipment is based on physical layer transport. | | | | important factor than the fact that FSO |
| This white paper discusses security aspects | | | | technologiesoffered one of the easiest and most |
| involving the physical layer. | | | | secure ways to exchange information between |
| Optical Wireless Systems and Network Security | | | | remote locations. The small diameter of the beam |
| With its cost-effective and high-bandwidth | | | | of typically only a few meters in diameter at the |
| qualities, optical wireless products operating in the | | | | target location is one of the reasons why it is |
| near infrared wavelength range are an alternative | | | | extremely difficult to intercept the communication |
| transport technology to interconnect highcapacity | | | | path of an FSO-based optical wireless system: |
| networking segments. These optical wireless | | | | The intruder must know the exact origination or |
| products, based on free-space optics (FSO) | | | | target location of the (invisible) infrared beam and |
| technology, are license-free worldwide. Optical | | | | can only intercept the beam within the very |
| wireless system installations are very simple, | | | | narrow angleof beam propagation. Even more |
| andthe equipment requires very little maintenance. | | | | difficult, the intruder must have free and |
| These features make optical wireless solutions | | | | undisturbed access to the installation location of |
| appealing to end-users and service providers | | | | the optical wireless transceiver and be able to |
| globally. As a result, the number of optical wireless | | | | install electronic equipment without being observed. |
| system installations to for enterprise, cellular, and | | | | In the majority of cases, the installation location |
| metropolitan area network traffic demands has | | | | does not allow free access to a potential intruder |
| increased significantlyeven during the recent | | | | because the installation location is part of the |
| telecommunications sector slowdown. | | | | customerpremise such as the roof or an office |
| Because optical wireless systems send and | | | | (when optical wireless equipment is installed |
| receive data through the air between remote | | | | behindwindows). |
| networking locations, network operators and | | | | The direct interception of an optical wireless beam |
| administrators are naturally concerned about | | | | between the two remote networking locations is |
| thesecurity aspects. One of the main reasons for | | | | basically impossible because the beam typically |
| this concern is based on the fact that wireless | | | | passes through the air at an elevation well above |
| networking solutions is a category in which | | | | ground level. Due to the fact that the transmission |
| security and interference problems are very | | | | beam is invisible and that any attempts to block |
| common in radio frequency (RF) or | | | | the beam would occur near the optical wireless |
| microwave-based communication systems. Such | | | | equipment terminus points, the transmission |
| concerns are not valid for optical wireless | | | | process imposes another obstacle. Picking up the |
| systems. | | | | signal from a location thatis not directly located |
| Optical wireless systems operate in the near | | | | within the light path by using light photons |
| infrared wavelength range slightly above the | | | | scattered from aerosol, fog, or rain particles that |
| visible spectrum. Therefore, the human eye | | | | might be present in the atmosphere is virtually |
| cannot visibly see the transmission beam. | | | | impossible because of the extremely low infrared |
| Thewavelength range around 1 micrometer that is | | | | power levels used during the optical wireless |
| used in optical wireless transmission systems is | | | | transmission process. Themain reason for |
| actually the same wavelength range used in | | | | excluding this possibility of intrusion is the fact that |
| fiber-optic transmission systems. The wavelength | | | | light is scattered isotropicallyand statistically in |
| range around 1 micrometer translates into | | | | different directions from the original propagation |
| frequencies of several hundred terahertz (THz). | | | | path. This specific scattering mechanism keeps |
| These frequencies are significantly (roughly three | | | | the total number of photons or the amount of |
| to four orders of magnitude) higher than the | | | | radiation that can potentiallybe collected onto a |
| highest frequencies used in commercially available | | | | detector that is not directly placed into the beam |
| microwave communications systems operating | | | | path well beyond the detector noise level |
| around 40 GHz. This difference in frequency of | | | | SummaryOptical wireless communication systems |
| operation is one of the main reasons whyoptical | | | | are among the most secure networking |
| wireless systems belong into the equipment | | | | transmission technologies. Unlike microwave |
| category of optical communication systems first | | | | systems, it is extremely difficult to intercept the |
| rather than wireless, RF or microwave, | | | | optical wireless light beam carrying networking |
| transmission solutions. While typical RF and | | | | data because the information is not spread out in |
| microwave antennas used to interconnect two | | | | space but rather kept in a very narrow cone of |
| remote networking locations in a | | | | light. To intercept this invisible light beam, the |
| point-to-pointarchitecture spread out the radiation | | | | intruder must be able to obtain direct access to |
| over angles between 5 and 25 degrees, optical | | | | the light beam. Due to the very narrow beam |
| wireless systems use very narrow beams that | | | | diameter, interception of the beam can virtually |
| are typically much less than 0.5 degrees. For | | | | only be accomplished at the customer premise |
| example, aradial beam pattern of 10 degrees | | | | where the system is installed. At that point, it |
| roughly corresponds to a beam diameter of 175 | | | | would be certainly easier for an intruder to plug |
| meters at a distance of 1 kilometer from the | | | | directly into the network by using the existing |
| originating source, whereas a beam of 0.3 | | | | copper-based infrastructure (e.g. unplug a CAT 5 |
| degrees divergence angle typically used in optical | | | | networking cable and plug it into a laptop). |
| wireless systems corresponds to a beam | | | | Scattered light can not be used as a method of |
| diameter of 5 meters atthe same distance.1 This | | | | interception.Moreover, higher protocol layers can |
| wide spreading of the beam in microwave | | | | be used in conjunction with layer one optical |
| systems, combined with the fact that microwave | | | | wireless physical transport technology to encrypt |
| antennas launch very high power level is the | | | | sensitive network information and provide |
| primary reason for security concerns. An outside | | | | additional. |