An implementation of wireless local loop fixed station

A WLL (wireless local loop) system provides a flexible and economical local telephone service in place of the traditional wireline local loop system. We propose a common air interface for a wideband CDMA (code division multiple access) WLL system. This paper describes the design and implementation of a WLL fixed station, which is a radio subscriber unit (RSU). The RSU is the subsystem of WLL ATP (wireless local loop air-interface test plant) implemented to verify the Korean WLL standard. It consists of three boards implemented with a processor and FPGAs. the three boards are the RF board, the demodulator board, and the modulator board which includes a processor and SLIM (subscriber line interface module). The structure and functions of modulator, demodulator, SLIM, and IF/RF are described