| 摘要 |
PROBLEM TO BE SOLVED: To drastically reduce the number of OLSTs arranged on a tower by transmitting a steerably modulated laser beam to each on of plural subscribers in an OLST viewing area and receiving a signal from a customer by means of OLST when being steered by a specified subscriber. SOLUTION: A free space optical wide band access system is constituted of a center hub 300 and elements such as an 'antenna' arranged in the respective subscribers 21-25, 43 and 44, however, a free space optical link and a laser are used in place of microwave radio. Optical beam scanning technique is utilized in the hub in order to rapidly move the beam from a certain user to another and optical number of virtual point-to-point links are formed. The two different wave lengths of an infrared beam are used in the upstream direction and the downstream direction. The hub is arranged at a sufficiently high position to directly view the multiple latent subscriber. Furthermore, the various and different groups of the subscribers are allotted by plural sectors in a configuration. |
