Patent ID: 6661835
Filing Date: 2003-12-09
Classification: H04B

Abstract:
A receiving device for CDMA (Code Division Multiple Access) communication, comprising:receiving means for receiving signals for CDMA sent from a plurality of transmitting stations to thereby output received signals; a first group of interference cancellation stage for estimating signals sent from the transmitting stations from the received signals by using despreading codes corresponding to spreading codes respectively assigned to the transmitting stations, wherein said first group of interference cancellation stage includes N (integer greater than 2 inclusive) interference cancelling units (ICUs) each for estimating an interstation interference ascribable to interference between the despreading codes, and estimates interstation interferences in parallel, cancels the interstation interferences and estimates the signals sent from said N transmitting stations in parallel; and a second group of interference cancellation stage for estimating, from signals from which the interstation interferences have been cancelled by said first group of interference cancellation stage, interstation interferences in parallel with M (integer greater than 2 inclusive) ICUs, cancelling the interstation interferences and estimates signals sent from said M transmitting stations in parallel, and outputting signals free from the interstation interferences; wherein a plurality of interference cancellation stages each comprising said first group of interference cancellation stage and said second group of interference cancellation stage are serially connected to construct a hybrid interference cancelling unit, and wherein each of said plurality of interference cancellation stages estimates interstation interferences while the ICLJs of a last one of said plurality of interference cancellation stages output the signals sent from the individual transmitting stations, wherein each of said ICUs includes finger circuits for performing Rake receipt, processing of estimated received symbols output from a previous one of said plurality of interference cancellation stages, and channel estimation, a signal correction and decision circuit for executing correction and decision with signals output from said finger circuits, and a respreading circuit for restoring signals output from said signal correction and decision circuit to same conditions as on a channel; wherein for the channel estimation, use is made of a known pilot symbol portion and a data portion included in each of the signals received from the transmitting stations; wherein each of said finger circuits estimates a channel by eliminating a phase of a correlation detection output by decision feedback based on a result of hard decision output from said signal correction and decision circuit, uses a moving average of several symbols of said correlation detection output as channel estimation information, and multiplies said correlation detection output by a complex conjugate of said channel estimation information to thereby produce a finger output; and wherein each of said finger circuits first estimates a channel by using only the pilot symbol portion and restores a phase rotation of a data symbol next to said pilot symbol portion to thereby demodulate a finger input, inputs the pilot symbol portion to a moving average filter, returns a result of hard decision executed with a result of demodulation of data to a channel estimator to thereby eliminate a data phase of a next correlation detection output, inputs a result of data phase elimination to said moving average filter, produces a mean of said pilot symbol portion and one symbol of data in said moving average filter and uses said mean as a result of channel estimation for demodulating a second data symbol as counted from said pilot symbol section, returns a result of hard decision executed with a result of demodulation of said second data symbol also to said channel estimator to thereby restore a phase of a third data symbol, and inputs said phase of said third data symbol to said moving average filter.