Patent ID: 6795488
Filing Date: 2004-09-21
Classification: H04B

Abstract:
A spread spectrum communication apparatus comprising:a spread spectrum signal receiving means for receiving channel information from a spread spectrum signal transmitting means for receiving spread output data of code channels transmitted from the spread spectrum signal transmitting means as a received signal composed of a plurality of incoming waves transmitted through a plurality of propagation paths, the spread spectrum signal receiving means comprising: searching means for searching the received signal for a plurality of specific incoming waves of a specific code channel according to channel information, whereby detecting a plurality of received electric powers of the specific incoming waves and a plurality of phase offsets of the specific incoming waves to search the received signal for conditions of their propagation paths, and for outputting a searcher detecting signal indicating the received electric powers of the specific incoming waves and the phase offsets of the specific incoming waves; signal holding means for holding the received signal during an interference removing operation; at least two finger units respectively having inverse code transforming means for detecting the received electric power of a particular incoming wave, which corresponds to a specific code channel and a particular phase offset allocated to the finger unit, from the signal that has been directly received from the spread spectrum signal transmitting means according to the channel information and the searcher detecting signal output from the searching means in the interference removing operation, specifying the spread code sequence and one particular distinguishing code corresponding to one particular code channel allocated to the finger unit according to the channel information, performing an inverse code transformation for the received signal with the particular distinguishing code and the spread code sequence in an interference removing demodulating operation to produce an inversely code transformed signal from the output data of the particular code channel distinguished by the particular distinguishing code, and demodulating means for demodulating the inversely code transformed signal produced by the inverse code transforming means to produce a finger demodulated symbol string of the particular code channel allocated to the finger unit; interference electric power detecting means for selecting the specific code channel, with respect to which the specific incoming waves have a substantial interference removing effect, from the code channels according to the channel information, receiving the particular incoming waves from the finger units, receiving the specific incoming waves from the searching means, determining a plurality of weighting factors corresponding to all specific incoming waves of the specific code channel according to the received electric powers of the particular incoming waves and a plurality of received electric powers of one or more specific incoming waves other than the particular incoming waves, weighting the particular incoming waves and the specific incoming waves other than the particular incoming waves with the corresponding weighting factors, and performing a despread spectrum for the particular incoming waves other than one particular incoming wave detected in one finger unit and the specific incoming waves other than the particular incoming waves detected by all finger units with the spread code sequence corresponding to the phase offset of each particular incoming wave or specific incoming wave to produce an interference replica signal corresponding to the finger unit for each of the finger units; signal allocating means for allocating the received signal directly transmitted from the spread spectrum signal transmitting apparatus to the finger units in the interference removing operation and allocating an interference removed received signal, which is obtained by subtracting the interference replica signal corresponding to one finger unit from the received signal held in the signal holding means, to the finger unit as the received signal in the interference removed demodulating operation for each of the finger units; channel synthesizing means for synthesizing a demodulated symbol string from the finger demodulated symbol strings produced by the finger units; decoding means for decoding the demodulated symbol string synthesized by the channel synthesizing means to reproduce the pieces of input data of the particular code channels allocated to the finger units; and control means for controlling the finger units, the interference electric power detecting means and the signal allocating means according to the channel information and the conditions of the propagation paths detected by the searching means to allocate the particular code channel to each finger unit according to the channel information, allocate the particular phase offset detected by the searching means to each finger unit, transmit the received signal directly transmitted from the spread spectrum signal transmitting means to the finger units in the interference removing operation and transmit the interference removed received signal produced by the interference electric power detecting means to the corresponding finger unit in the interference-removed demodulating operation for each of the interference-removed demodulating operations, wherein, in cases where the allocation of one particular code channel to all finger units is indicated by the channel information, the same particular code string corresponding to the particular code channel is selected from the code strings in the finger units according to the channel information under the control of the control means to perform an inverse code transformation with the same particular distinguishing code in each of the finger units, the phase offsets corresponding to the specific incoming waves detected by the searching means are allocated to the finger units in the order of decreasing of the received electric power of the specific incoming wave under the control of the control means, and the demodulation of a RAKE reception is performed in the finger units, and wherein, in cases where the allocation of a plurality of particular code channels to all finger units is indicated by the channel information, the particular distinguishing code corresponding to the particular code channel allocated to one finger unit is specified in the finger unit according to the channel information under the control of the control means for each of the finger units, a particular phase offset corresponding to the highest received electric power is selected from the phase offsets of the specific incoming waves detected by the searching means and is allocated to the finger units under the control of the control means, and the demodulations in the finger units are serially performed.