Wireless Local Loop (WLL) is a technology that connects subscribers to the public switched telephone network (PSTN) using radio signals to substitute the copper wires. The WLL sustem includes cordless access systems, proprietary fixed radio access, and fixed cellular systems. Sometimes WLL is called radio in the loop (RITL) or fixed-radio access (FRA). The bandwidth using WLL is much higher than that possible in the copper loop. Wireless local loop is a practical and economical last mile (or first mile) solution for connecting subscribers in areas that do not have the wired infrastructure such as remote rural area and some developing countries.

The WLL system is based on a full-duplex radio network that provides local telephone-like service among a group of users. The WLL unit consists of a radio transceiver and the WLL interface assembled in one metal box. Two cables and a telephone connector are the only outlets from the box; one cable connects to a directional antenna and a phone receptacle to connect to a common telephone set. A fax or modem could also be connected for fax or computer communication. WLL systems incorporating various types of wireless technologies as summarized as follows:

1. TDM/TDMA and P-MP communications equipment: The system uses communications equipment based on time division multiplex/time division access (TDM/TDMA) technology and a point-to-multipoint (P-MP) system provides service coverage over a wide area encompassing the base station, relay stations and subscriber stations.
2. Fixed use of cellular systems: This approach uses the wireless equipment of a cellular phone system, thereby curtailing the mobile function. Using cellular phones as the subscriber terminals makes it possible to hold down the system cost.
3. PHS-WLL system: The system uses PHS terminal technology and wireless equipment. Since the voice encoding system uses 32 kbps adaptive differential pulse code modulation (ADPCM), speech quality on a par with that of fixed telephony is obtained.

WLL: Wireless Local Loop

Related Terms: PSTN, RITL, FRA

Reference Links: http://www.iec.org/online/tutorials/wll/: Wireless Local Loop (WLL)