Presented by Raisa Tripathy Regd.no ETC

 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.

LOS Fresnel Zone

 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.

Non-Line-of-Sight Obstruction (complete blockage) Near-Line-of-Sight Obstruction (partial blockage)

NLOS CPE Location

 Point to point connection  Point to multipoint connection

Point-to-point connectivity

 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)

● 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

 Different methods:-  Passive random reflection  Tropospheric scatter link  Passive repeaters  Active repeaters

 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.

 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.

 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.

 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.

 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.

 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.

 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.

 WiMax  NLOS Missile  NLOS-LS Program to use Gedae for software development  NLOS cannon

The AW900xTR product line allows you to build a long-range, non-line-of-sight, point-to-multipoint wireless Ethernet solution.

 Features:-  Automatic target recognition  effective against both hard and soft targets. Can retarget and can transfer image.

Features: Range= 1/3 mile 360 Degree Horizontal 14 Degree Vertical Non Line-of-Sight Design 2.4GHz / 5GHz

 Features:-  fires rounds at sustained rate with a push of a button ●Maximum range of fire with standard projectile is 30 km.

 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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T HANK YOU!!!!