Optical wireless communication

Extract

[...] Scintillation and Free Space Optics (FSO) Performance of many Free Space Optics (FSO) optical wireless systems is adversely affected by scintillation on bright sunny days; the effects of which are typically reflected in BER statistics. Some optical wireless products have a unique combination of large aperture receiver, widely spaced transmitters, finely tuned receive filtering, and automatic gain control characteristics. In addition, certain optical wireless systems also apply a clock recovery phase-lock-loop time constant that all but eliminate the affects of atmospheric scintillation and jitter transference. [...]

[...] Broadband Bandwidth Alternatives Access technologies in general use today include telcoprovisioned copper wire, wireless Internet access, broadband RF/microwave, coaxial cable and direct optical fiber connections (fiber to the building; fiber to the home). Telco/PTT telephone networks are still trapped in the old Time Division Multiplex (TDM) based network infrastructure that rations bandwidth to the customer in increments of 1.5 Mbps or 2.024 Mbps DSL penetration rates have been throttled by slow deployment and the pricing strategies of the PTTs. Cable modem access has had more success in residential markets, but suffers from security and capacity problems, and is generally conditional on the user subscribing to a package of cable TV channels. [...]

[...] Since Free Space Optics (FSO) optical wireless transceivers can transmit and receive through windows, it is possible to mount Free Space Optics (FSO) systems inside buildings, reducing the need to compete for roof space, simplifying wiring and cabling, and permitting the equipment to operate in a very favorable environment. The only essential for Free Space Optics (FSO) is line of sight between the two ends of the link. Figure6: FSO bandwidth demand A recent New York Times article reported that more than 100 million miles of optical fiber was laid around the world in the last two years, as carriers reacted to the Internet phenomenon and end users' insatiable demand for bandwidth. [...]

[...] Therefore, a 1550 nm laser system is a good solution to achieving high data rates at long distances in the presence of poor propagation conditions (like fog) HIGH-SPEED BUILDING-TO-BUILDING CONNECTIVITY ENABLED WITH OPTICAL WIRELESS The problem: Today's Enterprises are experiencing a rising tide of network traffic that is overwhelming the typical connections that bridge buildings. With Enterprises standardizing on Fast Ethernet and Gigabit Ethernet (GbE) network speeds, the paltry 1.54 megabit connections between most buildings are heavily restricting throughput. Enterprises with large data requirements demand high throughput across Enterprise campus environments without the enormous costs of dedicated fiber-optic cable connections. [...]

[...] History of Free Space Optics Historically, Free Space Optics (FSO) or optical wireless communications was first demonstrated by Alexander Graham Bell in the late nineteenth century (prior to his demonstration of the telephone!). Bell's Free Space Optics (FSO) experiment converted voice sounds into telephone signals and transmitted them between receivers through free air space along a beam of light for a distance of some 600 feet. Calling his experimental device the “photo phone,” Bell considered this optical technology and not the telephone, his preeminent invention because it did not require wires for transmission. [...]