Wireless Local Loop - Unlicensed Multi Point Wireless Service

Unlicensed Multi Point Wireless Service

Most of the growth in long range radio communications since 2002 has been in the license free bands (mostly 900 MHz, 2.4 GHz and 5.8 GHz). Global Pacific Internet and Innetix started wireless service in California in 1995 using Breezecom (Alvarion) frequency hopping radio which later became the standard 802.11.

Few years later NextWeb Networks of Fremont beginning deploying reliable license free service. For Nextweb they originally deployed 802.11b equipment and later switched to Axxcelera which uses propriety protocol.

1995–2004

License-Free Equipment

Most of the early vendors of license free fixed wireless equipment such as Adaptive Broadband (Axxcelera), Trango Broadband, Motorola (Orthogon), Proxim Networks, RedLine and BreezeCom (Alvarion) used proprietary protocols and hardware, creating pressure on the industry to adopt a standard for unlicensed fixed wireless. These Mac Layers typically used a 15–20 MHz channel using Direct Sequence Spread Spectrum and BPSK, CCK and QPSK for modulation.

These devices all describe the customer premises wireless system as the Subscriber Unit "SU", and the operator transmitter delivering the last mile local loop services as the "Access Point" (AP). 802.11 uses the terms AP and STA (Station).

2002–2005

Wi-Fi local loop

Originally designed for short range mobile internet and local area network access, IEEE 802.11 has emerged as the de facto standard for unlicensed Wireless Local Loop. More 802.11 equipment is deployed for long range data service than any other technology. These systems have provided varying results, as the operators were often small and poorly trained in radio communications, additionally 802.11 was not intended to be used at long ranges and suffered from a number of problems, such as the hidden node problem. Many companies such as KarlNet began modifying the 802.11 MAC to attempt to deliver higher performance at long ranges. (see Long-range Wi-Fi)

2005–present

Maturation of the Wireless ISP market

In nearly every metropolitan area worldwide, operators and hobbyists deployed more and more unlicensed broadband point to multipoint systems. Providers that had rave reviews when they started faced the prospect of seeing their networks degrade in performance, as more and more devices were deployed using the license free U-NII (5.3/5.4 GHz) and ISM (2.4 and 5.8 GHz) bands and competitors sprung up around them.

The growing interference problem

Interference caused the majority of unlicensed wireless services to have much higher error rates and interruptions than equivalent wired or licensed wireless networks, such as the copper telephone network, and the coaxial cable network. This caused growth to slow, customers to cancel, and many operators to rethink their business model.

There were several responses to these problems.

2003

Voluntary frequency coordination (USA)

NextWeb, Etheric Networks, GateSpeed and a handful of other companies founded the first voluntary spectrum coordination body – working entirely independently of government regulators. This organization was founded in March 2003 as BANC, "Bay Area Network Coordination". By maintaining frequencies used in an interoperator database, disruptions between coordinating parties were minimized, as well as the cost of identifying new or changing transmission sources, by using the frequency database to determine what bands were in use. Because the parties in BANC comprised the majority of operators in the Bay Area, they used peer pressure to imply that operators who did not play nice would be collectively punished by the group, through interfering with the non cooperative, while striving not to interfere with the cooperative. BANC was then deployed in Los Angeles. Companies such as Deutsche Telekom joined. It looked like the idea had promise.

2005

Operators flee unlicensed for licensed

The better capitalized operators began reducing their focus on unlicensed and instead focused on licensed systems, as the constant fluctuations in signal quality caused them to have very high maintenance costs. NextWeb, acquired by Covad for a very small premium over the capital invested in it, is one operator who focused on licensed service, as did WiLine Networks. This led to fewer of the more responsible and significant operators actually using the BANC system. Without its founders active involvement, the system languished.

2005 to present

Adaptive network technology

Operators began to apply the principles of self healing networks. Etheric Networks followed this path. Etheric Networks focused on improving performance by developing dynamic interference and fault detection and reconfiguration. As well as optimizing quality based routing software, such as MANET and using multiple paths to deliver service to customers. This approach is generally called "Mesh Networking" which relies on ad hoc networking Protocols, however Mesh and ad-hoc networking protocols have yet to deliver high speed low latency business class end to end reliable local loop service, as the paths can sometimes traverse exponentially more radio links than a traditional star (AP->SU) topology.

Adaptive network management actively monitors the local loop quality and behaviour, using automation to reconfigure the network and its traffic flows, to avoid interference and other failures.