On a block coding ZCZ-CDMA scheme with high-speed processing

A quasi-synchronous CDMA scheme using a spreading code with a zero correlation zone called ZCZ code and a block cording technique with the Rake receiver with the pilot-symbol-aided channel estimation, which is called BC-ZCZ-CDMA, can almost remove the multiple access interference (MAI) and inter symbol interference (ISI) over multipass Rayleigh fading channel. In large delay spread with high-speed real-time transmission, it is necessary to increase the block size K in order to remove MAI and ISI. However the calculation of the inverse matrix in the Rake receiver lakes time of the cube order of the block size corresponding to the number of data symbols transmitted in one bundle, i.e., O(K3). This paper discusses BC-ZCZ-CDMA that LZCZ sequences is assigned to a user, and investigates the bit error rate performance over a mullipath Rayleigh fading channel. As final results, the number of users decreases, but the calculation time becomes O((K/L)3). Furthermore a pilot signal can be designed effectively, and the overall system will be simplified.