06-09-2012, 12:16 PM
WIRELESS OPTICAL COMMUNICATION
04Wireless Optical Communication.doc (Size: 602 KB / Downloads: 28)
ABSTRACT
This paper deals with the Wireless Optical Communication (WOC). In this paper we mainly discuss the problems with the conventional methods of communication such as Permissions, License fees, Lack of International standardization, Wastage of power and Security and how this new technology of WOC can be used to overcome these problems, along with its own set of advantages. We also discuss about the competitions it is facing and how it stands apart, and finally how low cost user friendly devices built using this technology can be used in the Rural Indian Scenario.
INTRODUCTION
As the term wireless optical communications (WOC) suggests, this is a group of technologies that use light to communicate through the air, and require clear line of sight between units. Modern systems typically use lasers or light-emitting diodes to produce the light at one end, while photo diodes at the receiver sense the incoming light, and send an appropriate signal to a connected computer.
In the telecommunications space, WOC systems are in use in niche applications, mostly for high-bandwidth applications needing to transfer hundreds of megabits per second, over distances typically less than a kilometer. Recent developments promise to bring WOC into the realm of inexpensive consumer products.
CURRENT SCHEMES OF WIRELESS COMMUNICATIONS
In the last decades, the use of wireless has grown at a furious pace. The advantages of wireless are rapid deployment, without the need to dig trenches for cables, and seek permissions for right of way. A big advantage of wireless is in allowing people to communicate while they are mobile. The systems in common use are:
Satellite
While satellites in low-earth orbit are sometimes used for communication, the most common are geostationary satellites, which are stationed approximately 34000 km away. These are particularly useful to bring communications to remote areas, and are also well suited to situations where the same content has to be delivered to a large number of people, as in the case of radio (Worldspace) and TV. Satellites, of course, are expensive to make and to maintain.
Radio
Over the years, a plethora of systems for radio communication have been developed. These use a variety of frequencies, as well as protocols for modulating the carrier frequency with data, and cover ranges from a few to thousands of kilometers. Perhaps the best recognized examples of such communication are the microwave towers scattered around the countryside.
WHY OPTICAL WIRELESS
Optical communication is, as a rule, a completely unregulated market, except to the extent required to protect the human eye from a strong beam. Under the IEC 8025 standard, to be unconditionally safe, devices must conform to a CLASS 1 designation This permits viewing at any range over any duration even using optical aids such as binoculars. The miliwatts of power typically used by modern optical communication systems are well below such limits. Since the frequencies used are unregulated, they attract no license fees, while the same frequencies can be used all over the world, eliminating the need for different models for different countries. A solution for South Asia could therefore easily be exported.
Laser beams can easily be focused very narrowly. "Laser pointers are cheap examples demonstrating mill radian collimation from a millimeter aperture. To get similar collimation for a 1 GHz RF signal would require an antenna 100 meters across, due to the difference in wavelength of the two transmissions. A similar advantage is seen at the receiver, where compact lenses can be used for optical beams, while radio signals need large and unwieldly antennae at the receiver end as well, to obtain significant improvement in efficiency. Because laser beams are tightly focused, it is nearly impossible for anyone to intercept them, or even to detect their use. Beams of light effortlessly pass through each other, without interfering. These considerations make it unlikely that optical communication will be regulated even in the future.
WOC PRODUCTS IN THE INTERNATIONAL MARKET
While most products allow only point-to-point communication, companies such as AirFiber and Terabeam have brought out products that easily allow a mesh of links between nodes to be set up. Prices are in the thousands, if not tens of thousands of dollars.
INDUSTRY PROBLEMS
The narrow beams used in wireless optical communications need to stay focused, even through wind and vibration. This requires special hardware for automatic alignment. Then again, weather and flying birds can interfere with quality reception. Consequently, the difficulties faced by the industry include:
High-speed, high cost niche
The products available in the market provide orders of bandwidth more than what the consumer needs, at a price she cannot afford. They are used when other methods are infeasible, or when a large amount of bandwidth needs to be provided at short notice, for instance during a conference.
Competition
Telecommunications is an industry with a high rate of innovation, with a variety of systems in use, which WOC must compete with. These include systems both, in the wired and wireless space. Only those that offer broadband connectivity are discussed here.
Optic Fiber
Much investment has taken place all over the world in this technology, which for long-distance high-bandwidth traffic has no equal. However, there are limitations: Almost 90 percent of all office buildings in the United States have no fiber connection. To link a building with fiber costs between $100,000 and $200,000 and often involves a provisioning delay of four to 12 months. Given the cost and time required, it is not realistic to expect optic fiber to reach all our villages any time soon.
CONCLUSION
Wireless optical communication has advanced far enough, that it encompasses all the benefits of conventional wireless - quick deployment and mobile communication, while delivering a million times more bandwidth than a GSM phone, providing much higher security and consuming far less power. Since, unlike conventional wireless, optical devices operate in globally unregulated frequency bands, they have an unrestricted global market. To make this technology marketable in rural South Asia, an end-user device costing under $10 is needed. A telephone handset that communicates optically with the base station would fit the bill.Our electrical industry has an understanding of the manufacturing processes of Opto-electronic equipment. Moving in a hi-tech direction such as this is becoming imperative for companies threatened by competition from across the Chinese border.
04Wireless Optical Communication.doc (Size: 602 KB / Downloads: 28)
ABSTRACT
This paper deals with the Wireless Optical Communication (WOC). In this paper we mainly discuss the problems with the conventional methods of communication such as Permissions, License fees, Lack of International standardization, Wastage of power and Security and how this new technology of WOC can be used to overcome these problems, along with its own set of advantages. We also discuss about the competitions it is facing and how it stands apart, and finally how low cost user friendly devices built using this technology can be used in the Rural Indian Scenario.
INTRODUCTION
As the term wireless optical communications (WOC) suggests, this is a group of technologies that use light to communicate through the air, and require clear line of sight between units. Modern systems typically use lasers or light-emitting diodes to produce the light at one end, while photo diodes at the receiver sense the incoming light, and send an appropriate signal to a connected computer.
In the telecommunications space, WOC systems are in use in niche applications, mostly for high-bandwidth applications needing to transfer hundreds of megabits per second, over distances typically less than a kilometer. Recent developments promise to bring WOC into the realm of inexpensive consumer products.
CURRENT SCHEMES OF WIRELESS COMMUNICATIONS
In the last decades, the use of wireless has grown at a furious pace. The advantages of wireless are rapid deployment, without the need to dig trenches for cables, and seek permissions for right of way. A big advantage of wireless is in allowing people to communicate while they are mobile. The systems in common use are:
Satellite
While satellites in low-earth orbit are sometimes used for communication, the most common are geostationary satellites, which are stationed approximately 34000 km away. These are particularly useful to bring communications to remote areas, and are also well suited to situations where the same content has to be delivered to a large number of people, as in the case of radio (Worldspace) and TV. Satellites, of course, are expensive to make and to maintain.
Radio
Over the years, a plethora of systems for radio communication have been developed. These use a variety of frequencies, as well as protocols for modulating the carrier frequency with data, and cover ranges from a few to thousands of kilometers. Perhaps the best recognized examples of such communication are the microwave towers scattered around the countryside.
WHY OPTICAL WIRELESS
Optical communication is, as a rule, a completely unregulated market, except to the extent required to protect the human eye from a strong beam. Under the IEC 8025 standard, to be unconditionally safe, devices must conform to a CLASS 1 designation This permits viewing at any range over any duration even using optical aids such as binoculars. The miliwatts of power typically used by modern optical communication systems are well below such limits. Since the frequencies used are unregulated, they attract no license fees, while the same frequencies can be used all over the world, eliminating the need for different models for different countries. A solution for South Asia could therefore easily be exported.
Laser beams can easily be focused very narrowly. "Laser pointers are cheap examples demonstrating mill radian collimation from a millimeter aperture. To get similar collimation for a 1 GHz RF signal would require an antenna 100 meters across, due to the difference in wavelength of the two transmissions. A similar advantage is seen at the receiver, where compact lenses can be used for optical beams, while radio signals need large and unwieldly antennae at the receiver end as well, to obtain significant improvement in efficiency. Because laser beams are tightly focused, it is nearly impossible for anyone to intercept them, or even to detect their use. Beams of light effortlessly pass through each other, without interfering. These considerations make it unlikely that optical communication will be regulated even in the future.
WOC PRODUCTS IN THE INTERNATIONAL MARKET
While most products allow only point-to-point communication, companies such as AirFiber and Terabeam have brought out products that easily allow a mesh of links between nodes to be set up. Prices are in the thousands, if not tens of thousands of dollars.
INDUSTRY PROBLEMS
The narrow beams used in wireless optical communications need to stay focused, even through wind and vibration. This requires special hardware for automatic alignment. Then again, weather and flying birds can interfere with quality reception. Consequently, the difficulties faced by the industry include:
High-speed, high cost niche
The products available in the market provide orders of bandwidth more than what the consumer needs, at a price she cannot afford. They are used when other methods are infeasible, or when a large amount of bandwidth needs to be provided at short notice, for instance during a conference.
Competition
Telecommunications is an industry with a high rate of innovation, with a variety of systems in use, which WOC must compete with. These include systems both, in the wired and wireless space. Only those that offer broadband connectivity are discussed here.
Optic Fiber
Much investment has taken place all over the world in this technology, which for long-distance high-bandwidth traffic has no equal. However, there are limitations: Almost 90 percent of all office buildings in the United States have no fiber connection. To link a building with fiber costs between $100,000 and $200,000 and often involves a provisioning delay of four to 12 months. Given the cost and time required, it is not realistic to expect optic fiber to reach all our villages any time soon.
CONCLUSION
Wireless optical communication has advanced far enough, that it encompasses all the benefits of conventional wireless - quick deployment and mobile communication, while delivering a million times more bandwidth than a GSM phone, providing much higher security and consuming far less power. Since, unlike conventional wireless, optical devices operate in globally unregulated frequency bands, they have an unrestricted global market. To make this technology marketable in rural South Asia, an end-user device costing under $10 is needed. A telephone handset that communicates optically with the base station would fit the bill.Our electrical industry has an understanding of the manufacturing processes of Opto-electronic equipment. Moving in a hi-tech direction such as this is becoming imperative for companies threatened by competition from across the Chinese border.