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Published byIrma Clark Modified over 8 years ago
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Presented by Raisa Tripathy Regd.no.0601208049 ETC
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What is LOS ? Line-of-sight (LOS) is a condition where a signal travels over the air directly from a wireless transmitter to a wireless receiver without passing an obstruction. Advantages: LOS is best for wireless communication. Signal can reach longer distance with better signal strength.
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LOS Fresnel Zone
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non-line-of-sight (NLOS) is a condition where a signal from a wireless transmitter passes several obstructions before arriving at a wireless receiver. The signal may be reflected, refracted, diffracted, absorbed or scattered.
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Non-Line-of-Sight Obstruction (complete blockage) Near-Line-of-Sight Obstruction (partial blockage)
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NLOS CPE Location
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Point to point connection Point to multipoint connection
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Point-to-point connectivity
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The obstructions that make LOS ineffective may be any of the three sizes as follows Much smaller than wavelength of the incident plane wave(wave will be unaffected) Of the same order as the wavelength(incident radio wave will be slightly attenuated) Much larger than a wavelength(incident wave will depend on the electrical property of the obstruction material)
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● Perfect conductor:-it will substantially reflect the radio waves that are incident upon it with almost the same power. Example:- bridges, metal clad buildings, storage warehouses, aircraft and electrical power transmission towers. Perfect insulator:-some RF power could be reflected at its boundaries depending on its relative permittivity compared to that of free space, which is unity. Intermediate conductivity:-incident wave will be partly reflected and partly absorbed, depending on the thickness
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Different methods:- Passive random reflection Tropospheric scatter link Passive repeaters Active repeaters
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Passive random reflections are achieved when plane waves are subject to one or more reflective paths around an object which makes an otherwise LOS radio path into NLOS. on each reflection the plane wave undergoes a transmission loss which must be compensated for by a higher output power from the transmit antenna compared to if the link had been LOS.
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ADVANTAGES:- The technique is cheap and easy to employ exploited in urban areas to achieve NLOS. Communication services :- ● Wi-Fi, WiMax, WiMax MIMO MIMO, mobile (cellular) communications and terrestrial broadcast to urban areas.
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The transmit beam is directed into the troposphere with sufficient power flux density that gas and water vapour molecules cause scattering. Some components of the scattered energy travel in the direction of the receiver antennas(very sensitive) and form the receive signal.
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Can be achieved by installing a precisely designed reflector at a critical position to provide a path around the obstruction. They have been successfully used in rural mountainous areas to extend the range of LOS microwave links around mountains thus creating NLOS links.
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An active repeater consists of a receiving antenna, a receiver, a transmitter and a transmitting antenna. If the ends of the NLOS link are at positions A and C, the repeater is located at position B where links A-B and B-C are in fact LOS. The active repeater may simply amplify the received signal and re-transmit it un-altered.
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For outdoor wireless solutions it deals with obstructions. Buildings, trees, and hills can’t obstruct RF signals when deploying broadband wireless. Nlos capable systems simplify network selection. WiMax offers operators the solution to address many applications with its outstanding performance in NLOS environment.
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Any wave that hits a moving object, for example a car, will experience a slight frequency shift. Echoes are distributed in time but also in frequency. Reliable NLOS links require a radio system able to tolerate increased path loss and a number of distorted echoes of the original signal.
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WiMax NLOS Missile NLOS-LS Program to use Gedae for software development NLOS cannon
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The AW900xTR product line allows you to build a long-range, non-line-of-sight, point-to-multipoint wireless Ethernet solution.
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Features:- Automatic target recognition effective against both hard and soft targets. Can retarget and can transfer image.
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Features: Range= 1/3 mile 360 Degree Horizontal 14 Degree Vertical Non Line-of-Sight Design 2.4GHz / 5GHz
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Features:- fires rounds at sustained rate with a push of a button ●Maximum range of fire with standard projectile is 30 km.
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To succeed in the NLOS fixed broadband wireless arena, operators must combine reliable technologies in a cost-effective manner. Improvements in antenna technology, more robust RF design, and forward-thinking system planning all must be carefully considered to deploy a successful, fixed- point, non-line-of-sight broadband wireless network.
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www.motorola.com/expedience www.motorola.com/expedience www.Skypilot.com www.Skypilot.com www.download3k.com www.download3k.com www.conniq.com www.conniq.com www.military-today.com www.military-today.com
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T HANK YOU!!!!
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