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A DS-CDMA transmission method capable of improving the accuracy of channel estimation using pilot symbols by eliminating cross-correlation between pilot symbols inserted into code channels in CDMA multiplexing carrying out fast signal transmission. In each frame assembler, the pilot symbols, which a

A DS-CDMA transmission method capable of improving the accuracy of channel estimation using pilot symbols by eliminating cross-correlation between pilot symbols inserted into code channels in CDMA multiplexing carrying out fast signal transmission. In each frame assembler, the pilot symbols, which are used for channel estimation for coherent detection, are inserted into coded information data on code channels at fixed intervals, and then the data is modulated by the modulator. The modulated data symbols in each code channel from the modulator are spread by the spreading modulator, the pilot symbols are spread using a spreading code, whereas the information symbols are spread using different spreading codes assigned to respective code channels. The spread signals of the code channels are summed up by the adder to be transmitted.

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1. A DS-CDMA transmission method using a code multiplexing method which transmits a transmission signal generated by code multiplexing through a plurality of code channels, said DS-CDMA transmission method comprising the steps of:coding an input data sequence, distributing the coded input data seque

1. A DS-CDMA transmission method using a code multiplexing method which transmits a transmission signal generated by code multiplexing through a plurality of code channels, said DS-CDMA transmission method comprising the steps of:coding an input data sequence, distributing the coded input data sequence to a plurality of data sequences in said plurality of code channels, and canying out interleaving for each of said plurality of said data sequences to which the coded input data sequence has been distributed; assembling frames for one of said code channels by adding pilot symbols to said interleaved data symbols in said data sequence at fixed intervals, said pilot symbols being used for channel estimation for coherent detection, and assembling frames for one or more code channels other than said one of said code channels including said interleaved data symbols without adding the pilot symbols; and spreading said interleaved data symbols in each of said plurality of code channels using a spreading code peculiarly assigned to said each of said plurality of code channels, said spreading code being selected from a group of orthogonal spreading codes that are orthogonal to each other, and spreading said pilot symbols, which are included in only one channel of said plurality of code channels, using one of the spreading codes being selected from said spreading codes assigned to said interleaved data symbols in said plurality of code channels, or any of the spreading codes from said group of orthogonal spreading codes other than the spreading codes assigned to said interleaved data symbols in said plurality of code channels. 2. The DS-CDMA transmission method as claimed in claim 1, wherein the spreading is performed such that the transmission signal is transmitted at the same transmission rate over each of said plurality of code channels.3. The DS-CDMA transmission method as claimed in claim 1, wherein said interleaving is carried out by writing data symbols and then reading the data symbols in a direction perpendicular to the direction in which the data symbols have been written.4. A DS-CDMA transmission method using a code multiplexing method which transmits a transmission signal generated by code multiplexing through the N code channels (N=>2), said DS-CDMA transmission method comprising the steps of:coding an input data sequence, distributing the coded input data to N data sequences in said N code channels, and carrying out interleaving for each of said N data sequences to which the coded input data sequence has been distributed; assembling frames for respective of said N code channels by adding pilot symbols to said interleaved data symbols at the same bit position of M code channels (1<=M<=N) among the N code channels, said pilot symbols being used for channel estimation for coherent detection, and assembling frames for (N?M) code channels other than said M code channels including said interleaved data symbols without adding the pilot symbols; and spreading said interleaved data symbols in each of said N code channels using a spreading code peculiarly assigned to said each of said N code channels, said spreading code being selected from a group of orthogonal spreading codes that are orthogonal to each other, and spreading said pilot symbols, which are included in said M code channels, using the same one code being selected from the spreading codes assigned to said interleaved data symbols in said N code channels, or any of the spreading codes from said group of orthogonal spreading codes other than the spreading codes assigned to said interleaved data symbols in said N code channels. 5. A DS-CDMA transmission apparatus using a code multiplexing method which transmits a transmission signal generated by code multiplexing through a plurality of code channels, said DS-CDMA transmission apparatus comprising:an encoder for coding input data; a distributor for distributing the coded input data to said plurality of code channels; a plurality of interleavers for carrying out interleaving for each of said plurality of code channels to which the coded input data has been distributed; a first frame assembler for assembling frames for one of said code channels by adding pilot symbols to data symbols at fixed intervals, said pilot symbols being used for channel estimation for coherent detection; one or more second frame assemblers for assembling frames for one or more code channels other than said one of said code channels without adding pilot symbols; a first spreading modulator for spreading said data symbols and said pilot symbols included in only one channel of said plurality of code channels, said data symbols are spread using a spreading code being selected from a group of orthogonal spreading codes that are orthogonal to each other, said pilot symbols are spread using one of the spreading codes being selected from spreading codes assigned to data symbols in said plurality of code channels, or any of the spreading codes from said group of orthogonal spreading codes other than the spreading codes assigned to said data symbols in said plurality of code channels; and one or more second spreading modulators for spreading said data symbols in each of said plurality of code channels using a spreading code peculiarly assigned to said each of said plurality of code channels, said spreading code being selected from said group of orthogonal spreading codes. 6. A DS-CDMA transmission apparatus using a code multiplexing method which transmits a transmission signal generated by code multiplexing through, the N code channels (N=>2), said DS-CDMA transmission apparatus comprising:an encoder for coding input data; a distributor for distributing the coded input data to said N code channels; N interleavers for carrying out interleaving for each of said N code channels to which the coded input data has been distributed; M first frame assemblers (1<=M<=N) for assembling frames for M code channels among the N code channels by adding pilot symbols to the data symbols at the same bit position of the M code channels, said pilot symbols being used for channel estimation for coherent detection; (N?M) second frame assemblers for assembling frames for (N?M) code channels other than said M code channels without adding pilot symbols; M first spreading modulators for spreading said pilot symbols and said data symbols included in said M code channels, said pilot symbols are spread using the same one spreading code being selected from spreading codes assigned to data symbols in said N code channels or any of the spreading codes other than the spreading codes assigned to said data symbols in said N code channels from a group of orthogonal spreading codes that are orthogonal to each other and said data symbols are spread using spreading codes peculiarly assigned to said each of said M code channels, said spreading code being selected from said group of orthogonal spreading codes; and (N?M) second spreading modulators for spreading said data symbols in each of said (N?M) code channels using a spreading code peculiarly assigned to said each of said (N?M) code channels, said spreading code being selected from said group of orthogonal spreading codes.