LONG Range WiFi

Introduction

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-multipointarrangement 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.
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Since the development of the IEEE 802.11 radio standard (marketed under the Wi-Fi brand name), the technology has become markedly less expensive and achieved higher bit rates. 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:

• poor signal penetration - 2.4 GHz connections are effectively limited to line of sight or soft obstacles
• far less range - GSM or CDMA cell phones can connect reliably at > 10 mile distances. The range of GSM, imposed by the parameters of Time division multiple access, is set at 35 km.
• few service providers commercially support long distance Wi-Fi connections

Despite a lack of commercial service providers, applications for long range Wi-Fi have cropped up around the world. It has also been used in experimental trials in the developing world to link communities separated by difficult geography with few or no other connectivity options. Some benefits of using long range Wi-Fi for these applications include:

• unlicensed spectrum - avoiding negotiations with incumbent telecom providers, governments or others
• smaller, simpler, cheaper antennas - 2.4 GHz antennas are less than half the size of comparable strength 900 MHz antennas and require less lightning protection
• availability of proven free software like OpenWrt, DD-WRT, Tomato that works even on old routers (WRT54G for instance) and makes modes like WDS, OLSR, etc., available to anyone. Including revenue sharing models for hotspots.

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.

Applications

Business

• Provide coverage to a large office or business complex or campus.
• Establish point-to-point link between large skyscrapers or other office buildings.
• Bring Internet to remote construction sites or research labs.
• Simplify networking technologies by coalescing around a small number of Internet related widely used technologies, limiting or eliminating legacy technologies such as shortwave radio so these can be dedicated to uses where they actually are needed.

Residential

• Bring Internet to a home if regular cable/DSL cannot be hooked up at the location.
• Bring Internet to a vacation home or cottage on a remote mountain or on a lake.
• Bring Internet to a yacht or large seafaring vessel.
• Share a neighborhood Wi-Fi network.

Nonprofit/Government

• Connect widespread physical guard posts, e.g. for foresters, that guard a physical area, without any new wiring
• In tourist regions, fill in cell dead zones with Wi-Fi coverage, and ensure connectivity for local tourist trade operators
• Reduce costs of dedicated network infrastructure and improve security by applying modern encryption and authentication.

Military

• Connect critical opinion leaders, infrastructure such as schools and police stations, in a network local authorities can maintain
• Build resilient infrastructure with cheaper equipment than an impoverished war-torn region can afford, i.e. rather than using a military-class network technology that must leave with the developed-world military, use (and leave behind) commercial grade tools
• Reduce costs and simplify/protect supply chains by using cheaper simpler equipment that draws less fuel and battery power; In general these are high priorities for commercial technologies like Wi-Fi especially as they are used in mobile devices.
  

Scientific research

• A long range seismic sensor network was used during the Andean Seismic Project in Peru. A multi-hop span with a total length 200 miles was crossed with some segments around 30 to 50 kilometers. The goal was to connect to outlying stations to UCLA in order to receive seismic data in real time.