Correlated noise cancellation in fractional sampling orthogonal frequency and code division multiplexing with alternative spreading code

Orthogonal frequency and code division multiplexing (OFCDM) has received large attention as a modulation scheme to realise high data rate transmission. The OFCDM system with fractional sampling (FS) is investigated. FS is a diversity scheme with a single antenna, which achieves path diversity through oversampling and parallel signal reception. However, the correlation among noise components may deteriorate the bit error rate performance at the receiver as the number of subcarriers and oversampling ratio increases. To overcome this problem, the alternative spreading code is used for the FS OFCDM system. Numerical results through computer simulation show that the proposed scheme can improve the performance of the receiver with the large oversampling ratio and the number of subcarriers.