This report addresses technologies and marketplace for two Free Space Optics communications types.
They are:
Wireless Fiber Communications (WFC), and
Visible Light Communications (VLC).
As shown in the report, though these technologies are based on different principles, they both use light as a transmission media and have many other similarities.
The WFC market development still remains uncertain. Though this report showed the potential market with wide open doors, it is presented only by a compact group of vendors (with such leaders as fSONA and LightPointe); recently, some vendors went out of business, or discontinued WFC products. On the one hand, the push for ever-greater bandwidth could eventually outrun any RF capacity, forcing a shift to WFC. On the other hand, RF techniques have a long head start in inside-building applications, and the weather problem remains a severe one for WFC inter-building links. Perhaps the best overall prospects are in space, where progress is being made in improving acquisition and tracking. Once these are perfected, the bandwidth advantages of optical free-space communications should open up a substantial market niche. Another segment of the WFC market-military-is also developing relatively fast and is supported by various government-sponsored programs. The report summarizes recent trends in the WFC market development and shows benefits of its use in multiple applications. The technology is perfecting, using multiple lasers and optical-microwave protection as well as advances in optics; it is also shifting from the 800 nm widow to the 1500 nm window, allowing more transmit power.
In the WFC channel, the highest speed achieved for practical purposes is 10 Gb/s; some vendors claim a transmission path up to 5 km with at least 99.9% availability for lower speeds. The report also analyzes the WFC market and assesses its characteristics. In the authors’ opinion, WFSs will continue to be used in niche applications, and the technology advances will make this industry stronger and stronger each year. Several of the most important factors that help the FSO market to grow are cost, short deployment time and maintenance-free communications channel. It seems that in the today weak economy users are looking for technologies that can produce satisfactory results for minimum investments-and that what WFSs can do better than RF systems.
The second part of the report discusses Visible Light Communications (VLC) properties, advantages and limitations. A visible light communication utilizing LEDs has many advantages such as visibility of information, high SNR (Signal to Noise Ratio), low installation cost, usage of existing illuminators, and high security. Furthermore, exponentially increasing needs and quality of LED have helped the development of visible light communication. The visible light communication is very suitable to the ubiquitous environment in terms of human interface to assure the comfortable human life.
VLC is still in a stage of development. It is in the process of standardization by the IEEE 802.15.7 group and Visible Light Communications Consortium (VLCC), as well as other standard organizations (such as Jeita). The VLCC was formed in 2003; but only at the present time it published the specifications (in cooperation with the IrDA and ICSA). Jeita also issued two documents to standardize VLC. The IEEE 802.15.7 group work is in progress.
There are experimental VLC systems and prototypes. The majority of the development is concentrated in Japan; in the U.S, projects are concentrated mainly in research arms of universities (such as Boston University).
The report provides the analysis of the current VLC trends, and shows great potential of this technology. Its utilization is in the agreement with Green Telecom concept-LEDs have long life span and do not contain any harmful materials (such as mercury); they also require much less power than traditional light sources. It is also in the agreement with the overall requirement to telecom- sustain as large as possible the ratio of b/$ (transmit bits per dollars spent). The progress in the LED development allows currently supporting the LED modulation speed in the range of 50 Mb/s-200 Mb/s; with experimental devices allow increasing this speed to 1Gb/s-3 Gb/s. As it is envisioned, the VLC market will evolve in the 2012-2014 time frame, with multiple indoor and even outdoor applications.
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