METHOD AND APPARATUS OF MULTI-MODE SUBTRACTIVE INTERFERENCE CANCELLATION FOR ASYNCHRONOUS MULTI-PATH CHANNELS IN CDMA SYSTEM

摘要

PURPOSE: A multiple mode subtracting type noise eliminating method and an apparatus thereof are reduce interfering noise generated by multiple access, thereby increasing performance and capacity of a CDMA(code division multiple access) system. CONSTITUTION: A root pulse shaping filter(402) converts a received intermediate signal into a baseband signal. A buffer(404) stores the baseband signal converted by the route forming filter. A timing circuit(414) receives the baseband signal output from the buffer to perform a PN code acquisition and tracking operation. A PN code generating portion(416) generates the same PN code as a PN code used in a transmitted signal using synchronous acquisition information output from the synchronous acquisition circuit. A demodulating portion(418) performs a PN inverse spreading and a walsh inverse spreading of the baseband signal. A channel and power estimating portion(419) estimates amplitude of vibration, a phase and a power value which are channel parameters. A mode selector and switch controller(432) decides ranking of the power value, and selects a proper noise eliminating mode in consideration of the number of user, channel environment and speed of hardware.