BTS interface subsystem in IMT-2000 base station controller

PURPOSE: A BTS interface subsystem(BIS) for an IMT-2000 base station controller is provided to concentrates a main control function and remove an unnecessary repetition function performance by embodying an ASS(Assembly Symbol Subsystem) for performing an ATM cell type converting function and an ATM switch interface function. CONSTITUTION: A processor(115) control an entire operation of a BIS. A plurality of E1 interface units(111a-111d) perform the recovery and encoding function of data transmitted through an E1 line. A plurality of ATM physical layer performing units(112a-112d) extract ATM cells from the E1 frame data transmitted from the E1 interface units(111a-111d) to perform an error correction and cell rate decoupling function of an ATM cell header, and perform the inverse function to transmit data to a BTS. A receipt multiplexing unit(113) transmits an internal control signal among the ATM cells transmitted from the ATM physical layer performing units(112a-112d) to the processor(115) and transmits residual ATM cells to a receipt type converting unit(114). The receipt type converting unit(114) classifies the ATM cells transmitted from the receipt multiplexing unit(113) into an AAL5 ATM cell and an AAL2 ATM cell, and bypasses the AAL5 ATM cell to the receipt multiplexing unit(113) and converts the AAL2 ATM cell into an AAL2 ATM cell to transmit the AAL2 ATM to the receipt multiplexing unit(113). A transmission multiplexing unit(116) transmits an internal control signal among ATM cells transmitted from a 155Mbps physical layer performing unit(118) to the processor(115) and transmits residual ATM cells to a transmission type converting unit(117).