Long-range Wi-Fi is used for low-cost, unregulated point-to-point computer network connections, as an alternative to other fixed wireless, cellular networks or satellite Internet access.
Wi-Fi networks have a range that's limited by the transmission power, antenna type, the location they're used in, and the environment.
A typical wireless router in an indoor point-to-multipoint arrangement using 802.11b or 802.11g and a stock antenna might have a range of 32 metres (105 ft).
Outdoor point-to-point arrangements, through use of directional antennas, can be extended with many kilometers between stations.
Long range Wi-Fi especially in the 2.4 GHz band (as the shorter range higher bit rate 5.8 GHz bands become popular alternatives to wired LAN connections) have proliferated with specialist devices from many vendors including Premiertek CPE, Ubiquiti, EnGenius, Luxul and the Cisco AiroNet line.
While Wi-Fi hotspots are ubiquitous in urban areas, some rural areas use more powerful longer range transceivers as alternatives to cell (GSM, CDMA) or fixed wireless (Motorola Canopy and other 900 MHz) applications.
The main drawbacks of 2.4 GHz vs. these lower-frequency options are: Despite a lack of commercial service providers, applications for long range Wi-Fi have cropped up around the world.
Some benefits of using long range Wi-Fi for these applications include: Nonprofit organizations operating widespread installations, such as forest services, also make extensive use of long-range Wi-Fi to augment or replace older communications technologies such as shortwave or microwave transceivers in licensed bands.
The Technology and Infrastructure for Emerging Regions (TIER) project at University of California at Berkeley in collaboration with Intel, uses a modified Wi-Fi setup to create long-distance point-to-point links for several of its projects in the developing world.
This technique, dubbed Wi-Fi over Long Distance (WiLD), is used to connect the Aravind Eye Hospital with several outlying clinics in Tamil Nadu state, India.
In most standard Wi-Fi routers, the three standards, a, b and g, are enough.
But in long-range Wi-Fi, special technologies are used to get the most out of a Wi-Fi connection.
On the other hand, using dual antennas with orthogonal polarities along with a 2x2 MIMO chipset effectively enable two independent carrier signals to be sent and received along the same long distance path.
Specially shaped directional antennas can increase the range of a Wi-Fi transmission without a drastic increase in transmission power.
High gain antenna may be of many designs, but all allow transmitting a narrow signal beam over greater distance than a non-directional antenna, often nulling out nearby interference sources.
The standard IEEE 802.11 protocol implementations can be modified to make them more suitable for long distance, point-to-point usage, at the risk of breaking interoperability with other Wi-Fi devices and suffering interference from transmitters located near the antenna.
Methods that stretch the range of a Wi-Fi connection may also make it fragile and volatile, due to mundane problems including: Obstacles are among the biggest problems when setting up a long-range Wi-Fi.
Sheet metal in walls or roofs, may efficiently reflect Wi-Fi signals, causing signal loss or multipath problems.
By its very nature, "long range" connotes an antenna system which can see many of these devices, which when added together produce a very high noise floor, whereby no single signal is usable, but nonetheless are still received.
The aim of a long range system is to produce a system which over-powers these signals and/or uses directional antennas to prevent the receiver "seeing" these devices, thereby reducing the noise floor.
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