RADIO INTERFACE UNIT(RIU) OF WIRELESS LOCAL LOOP SYSTEM HAVING PERSONAL COMPUTER MODEM FUNCTIONS

摘要

PURPOSE: A radio interface unit(RIU) of a wireless local loop(WLL) system is provided to build a personal computer(PC) for data communication services only among RIU functions, by being operated with a built-in modem of the PC connected to a telephone network. CONSTITUTION: A radio interface unit(RIU) of a wireless local loop(WLL) system comprises a radio frequency(RF) unit(10), a low pass filter(LPF)(21), an analog to digital(A/D) converter(22), a digital to analog(D/A) converter(23), a code division multiple access(CDMA) modem(24), a timing/switching controller(25), a data process/main controller(26), and a personal computer(PC) bus interface(27). The RF unit connected to a base station converts an RF signal of the base station into an intermediate frequency(IF) signal, or converts analog IF signals of subscribers into RF signals. The LPF passes required band analog IF signals to input/output the analog IF signals. The A/D converter converts the analog IF signals of the LPF into digital data. The D/A converter converts the digital data into analog IF signals to output the signals to the LPF. The CDMA modem decodes and despreads the digital data to convert the data into baseband signals, or encodes and band-spreads the converted baseband digital data to output the data to the D/A converter. The timing/switching controller supplies reference timing signals, and switches the baseband digital data to a corresponding path or switches the baseband digital data to output the data to the CDMA modem. The data process/main controller controls operations of the timing/switching controller and processes data for data communication services, then supports various communication protocols. The PC bus interface interfaces with a PC bus, and outputs 64Kbps pulse code modulation(PCM) data related to the data communication services to the timing/switching controller through the data process/main controller.