| 摘要 |
The present invention discloses a CDMA coding method including the steps of converting the information to be transmitted into digital form, error-correction coding the digital information, and assembling the coded symbols into frames having N symbols. Each coded information symbol within a frame is then repeated a first number of times L1 in succession and the sign of select repeated symbols, determined by a spreading code generator, is changed to produce a symbol block of NxL1 symbols. The symbol block is then repeated a second umber of times L2, where for each block repeat, a block sign change is applied to all symbols of the same block; the sign for each block may also be supplied by the spreading code generator. The resulting L2xNxL1 coded and repeated symbols are then modulated upon a radio frequency carrier and transmitted to a receiver simultaneously with similar symbols intended for other receivers, where different information is transmitted to a plurality of receivers. Signals coded for simultaneous transmission to different receivers may include a greater number of information symbols repeated a reduced number L1 times or a lesser number of information symbols repeated a greater number L1 times, while still maintaining the same number of repeated symbols in a block. By assigning specific block-spreading sequences to groups of signals in various adjacent service areas or according to transmitter-receiver distance, strong signals can be better discriminated from weak signals and inter-cell interference can be reduced.
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