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Wireless local loop (WLL), is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service (POTS) and/or broadband Internet to telecommunications customers. The last Mile is the final leg of delivering connectivity from a communications provider to a customer The last Mile is the final leg of delivering connectivity from a communications provider to a customer The term broadband can have different meanings in different contexts The Internet is a global system of interconnected Computer networks Various types of WLL systems and technologies exist.

Other terms for this type of access include Broadband Wireless Access (BWA), Radio In The Loop (RITL), Fixed-Radio Access (FRA) and Fixed Wireless Access (FWA).


Contents

Definition of Fixed Wireless Service

Fixed Wireless Terminal (FWT) units differ from conventional mobile terminal units operating within cellular networks - such as GSM - in that a fixed wireless terminal or desk phone will be limited to an almost permanent location with almost no roaming abilities. A cellular network is a Radio network made up of a number of radio cells (or just cells) each served by a fixed transmitter known as a Cell GSM ( Global System for Mobile communications: originally from Groupe Spécial Mobile) is the most popular standard for Mobile phones in the Roaming is a general term in Wireless Telecommunications that refers to the extending of connectivity service in a location that is different from the home location

WLL and FWTs are generic terms for radio based telecommunications technologies and the respective devices which can be implemented using a number of different wireless and radio technologies.

Wireless Local Loop service is segmented into a number of broad market and deployment groups. Services are split between Licensed - commonly used by Carriers and Telcos - and Unlicensed services more commonly deployed by home users and Wireless ISPs (WISPs).

Licensed Point to Point Microwave service

Licensed Microwave service has been used since the 1960s to transmit very large amounts of data. The AT&T Long Lines coast to coast backbone in the USA was largely carried over a chain of microwave towers. AT&T Communications Inc is a IXC / Long distance telephone company owned by AT&T. These systems have been largely using 3700-4200 MHz and 5000-6200 MHz. The 5 GHz band was even known as the "common carrier" band. This service typically was prohibitively expensive to be used for Local Loop, and was used for backbone networks. In the 80s and 90s it flourished under the growth of cell towers. This growth spurred research in this area, and as the cost continues to decline, it is being used as an alternative to T-1, T-3, and fiber connectivity.

Licensed Point to Multi Point Microwave service

Multipoint microwave licenses are generally more expensive than point to point licenses. A single point to point system could be installed and licensed for 50,000 to 200,000 USD. A multipoint license would start in the millions of dollars. Multichannel Multipoint Distribution Service (MMDS) and Local Multipoint Distribution Service (LMDS) were the first true multi point services for wireless local loop. MMDS is also an acronym for Mortality Medical Data System. Multichannel multipoint distribution service, also known as MMDS LMDS is a Broadband wireless access technology governed by the IEEE and is outlined by the 802 LAN/MAN Standards Committee through the efforts of the IEEE 802 While Europe and the rest of the world developed the 3500 MHz band for affordable broadband fixed wireless, the U. S. provided LMDS and MMDS, and most implementations in the United States were conducted at 2500 MHz. The largest was Sprint Broadband's deployment of Hybrid Networks equipment. Sprint was plagued with difficulties operating the network profitably, and service was often spotty, due to inadequate radio link quality.

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 Terago Networks in Canada and 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. Alvarion Ltd ( NASDAQ:ALVR TASE:ALVR is a leading provider of WiMAX and non-WiMAX wireless broadband systems to carriers ISPs and private network operators 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, 802.11 has emerged as the de facto standard for unlicensed Wireless Local Loop. The Mobile Web refers to the access to the World Wide Web using a mobile device such as cell phones, PDAs, and other portable gadgets connected to a public IEEE 80211 is a set of standards for wireless local area network (WLAN computer communication developed by the IEEE LAN/MAN Standards Committee ( IEEE 802 A de facto standard is a Standard (formal or informal that has achieved a dominant and accepted position 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. In Wireless networking, the hidden node problem occurs when a node is visible from a wireless Access point (AP but not from other nodes communicating 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. See also Wi-Fi Long-range Wi-Fi is used for low-cost unregulated point-to-point connections as an alternative to cellular networks microwave or satellite links 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. 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: Operators develop 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. Etheric Networks is based in Mountain View California and provides high speed Internet access to the greater Bay Area 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.

2006 - 2008: The Next Technology - WiMAX (or IEEE 802.16)

Currently more operators are running on the 802.11 MAC at 2 and 5 GHz. WiMAX, an approximate acronym of Worldwide Interoperability for Microwave Access, is a Telecommunications technology that provides for the wireless transmission The IEEE 80216 Working Group on Broadband Wireless Access Standards, which was established by IEEE Standards Board in 1999 aims to prepare formal specifications IEEE 80211 is a set of standards for wireless local area network (WLAN computer communication developed by the IEEE LAN/MAN Standards Committee ( IEEE 802 802. 16 is unlikely to outperform 802. 11 until unlicensed 802. 16 equipment becomes available. It may become the dominant medium for wireless local loop. Intel is promoting this standard, while Atheros and Broadcom are still focused largely on 802. 11. Atheros, using its highly successful 802. 11 OFDM chipsets, will likely be able to deliver comparable service levels to Intel's 802. 16 TDM OFDM chipsets for the foreseeable future.

Mobile Technologies

These are available in Code Division Multiple Access(CDMA), Digital Enhanced Cordless Telecommunications - DECT (TDMA/DCA) ( See ETSI 6 EN 300 765-1 V1. Code division multiple access ( CDMA) is a Channel access method utilized by various radio communication technologies DECT or Digital Enhanced Cordless Telecommunications (formerly Digital European Cordless Telephone is an ETSI standard for digital Portable phones 3. 1 (2001-04) -"Digital Enhanced Cordless Telecommunications (DECT); Radio in the Local Loop (RLL) Access Profile (RAP); Part 1: Basic telephony services"), Global System for Mobile Communications(GSM), IS136 Time Division Multiple Access(TDMA) as well as analog access technologies such as Advanced Mobile Phone System(AMPS), for which there will be independent standards defining every aspect of modulation, protocols, error handling, etc. GSM ( Global System for Mobile communications: originally from Groupe Spécial Mobile) is the most popular standard for Mobile phones in the This article is about the medium access technology The name "TDMA" is also commonly used in the United States to refer to D-AMPS, which is a mobile telephone Advanced Mobile Phone System (AMPS is the analog Mobile phone system standard developed by Bell Labs, and officially introduced in the Americas

Deployment

The Wireless Local Loop market is currently an extremely high growth market, offering Internet Service Providers immediate access to customer markets without having to either lay cable through a metropolitan area MTA, or work through the ILECs, reselling the telephone, cable or satellite networks, owned by companies that prefer to largely sell direct. ILEC, short for Incumbent local exchange carrier, is a local Telephone company in the United States that was in existence

This trend revived the prospects for local and regional ISPs, as those willing to deploy fixed wireless networks were not at the mercy of the large telecommunication monopolies. They were at the mercy of unregulated re-use of unlicensed frequencies upon which they communicate.

Due to the enormous quantity of 802. 11 "Wi-Fi" equipment and software, coupled with the fact that spectrum licenses are not required in the ISM and U-NII bands, the industry has moved well ahead of the regulators and the standards bodies. The industrial scientific and medical (ISM Radio bands were originally reserved internationally for the use of RF electromagnetic fields for industrial scientific and medical The Unlicensed National Information Infrastructure ( U-NII) Radio band is part of the Radio frequency spectrum used by IEEE-802

Sprint and ClearWire were preparing to roll out massive WiMAX networks in the United States, but those talks may be stalled pending new investment. [1]

Wireless Local Loop (WLL) Standards

See also

Manufacturers

References

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